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FAAH Gene Variation Moderates Stress Response and Symptom Severity in Patients with Posttraumatic Stress Disorder and Comorbid Alcohol Dependence
Abstract
Background:
A common single nucleotide polymorphism (C385A) in the human fatty acid amide hydrolase (FAAH) gene has been associated with decreased distress responses in healthy volunteers, but its role in psychiatric disorders remains unknown. Here, we obtained genotypes and carried out a secondary analysis of subjects from a trial of comorbid posttraumatic stress disorder (PTSD) and alcohol dependence (AD). We evaluated the effects of C385A variation on behavioral and biochemical biomarkers of distress responses.
Methods:
Forty-nine patients with PTSD and AD were admitted for 4 weeks to an experimental medicine unit at the National Institutes of Health Clinical Center. Following detoxification, stress reactivity and peripheral endocannabinoid (eCB) levels were assessed in response to a challenge session using personalized auditory guided imagery. Over the course of the study, subjects were also evaluated for changes in PTSD symptom severity.
Results:
FAAH C385A allele carriers showed a marked increase in serum anandamide levels at baseline and throughout the stress challenge procedure compared with C allele homozygotes, while levels of eCBs primarily metabolized through other enzymatic activity, such as 2-arachidonoylglycerol, did not differ between genotype groups. FAAH C385A carriers also had decreased subjective anxiety responses to the stress challenge. Similar effects of FAAH C385A genotype were found at the level of clinical PTSD symptom severity, in particular in the arousal domain.
Conclusions:
This is to our knowledge the first study showing that FAAH C385A variation modulates stress responses in subjects with disorders characterized by increased stress reactivity. These findings point to the eCB pathway as a promising target for future antistress therapeutics.
... [21][22][23] Several studies demonstrated that A-allele carriers were associated with decreased anxiety, enhanced fear extinction learning and extinction recall, decreased threat-related amygdala reactivity, increased fronto-amygdala connectivity, and protected against stress-induced decreases in AEA and negative emotional consequences of stress. 16,[24][25][26][27][28][29] Interestingly, these studies did not assess or correct for childhood trauma in their analysis, despite evidence showing that it can cause alterations in the ECS. [30][31][32] Taken together, these studies support the role of decreased FAAH activity and increased AEA levels in buffering stress responses besides its enhancement of fear extinction. ...
... 40 So far, studies have mainly focused on populations that already have developed anxiety and trauma-related symptoms or in healthy individuals on stress and anxiety in an experimental setting. 16,[24][25][26][27][28][29] However, it remains unknown whether potential genetic variations of the FAAH, CRHR1 and CNR1 polymorphisms are protective in the development of anxiety and trauma-related symptoms in real life events. Therefore, the primary aim of the current study is to examine the relationship between genetic variations in the FAAH rs324420 polymorphism (ie AA and AC-allele carriers) and the development of anxiety and trauma-related symptoms after the experience of stressful events in military veterans who have been deployed in Afghanistan. ...
... Since AA carriers often form a small group, they are frequently grouped together in such analyses. 16,[24][25][26][27][28][29] In the explorative analysis FAAH rs324420 (CC and AC/AA) and childhood trauma (no childhood trauma, low and high childhood trauma) were added as fixed effect and Time (anxiety or PTSD scores predeployment and 6 months after deployment) the dependent variable. ...
Background
During military deployment, stress regulation is vital to protect against the development of anxiety and trauma-related symptoms. Brain endocannabinoids play an important role in stress regulation and previous research has shown that genetic variations in the FAAH rs324420 polymorphism demonstrate protective effects during stress. In addition, this polymorphism shows interactions with the CRHR1 and CNR1 polymorphisms on anxiety. The present study examines whether genetic variations of the FAAH, CRHR1 and CNR1 polymorphisms interact with the development of anxiety and trauma related symptoms in military veterans.
Methods
Veterans (N = 949) who went on military deployment and experienced a stressful event were genotyped for FAAH rs324420, CRHR1 rs110402 and CNR1 rs2180619. Anxiety and trauma symptoms were measured pre-deployment and 6 months after deployment. Anxiety was measured with the anxiety subscale of the Symptom Checklist-90 (SCL-90) and trauma with the Self-Rating Inventory for PTSD (SRIP).
Results
Covariance Pattern Models demonstrated no significant relation of genetic variations in FAAH rs324420 on anxiety and PTSD symptoms from pre-deployment to 6 months after military deployment. Additionally, we investigated interactions between the FAAH s324420, CRHR1 rs110402 and CNR1 rs2180619 polymorphisms. This also demonstrated no significant effects on anxiety and PTSD symptoms pre- to post deployment. However, the covariate of childhood trauma that was included in the models was significant in all these models.
Conclusion
Genetic variations in FAAH rs324420 and its interactions with CRHR1 rs110402 and CNR1 rs2180619 are not related to the development of anxiety and trauma-related symptoms. The study however, indicates the importance of considering childhood trauma in the investigation of the effects of polymorphisms that are related to the endocannabinoid system on the development of anxiety and PTSD symptoms.
... Antidepressant treatment was reported in a total of 135 patients (96 MDD and 39 AUD patients). Two studies [61,62] did not report antidepressant use, and six studies [45,60,[63][64][65][66] excluded patients taking antidepressants. In two other studies [67,68], all MDD patients were being treated with antidepressants. ...
... Included studies found no significant correlation between AUD diagnosis, AUD severity or length of abstinence and peripheral levels of 2-AG [60,62,72]. ...
... Besides, Meyer and colleagues [69] found a significant increase in AEA following moderateintensity exercise, which was associated with decreases in anxiety. Moreover, a genotype study [62] of two cohorts, consisting of 25 low-expressing FAAH variant (385 A carriers) and 24 common FAAH variant, showed that 385 A carriers had higher serum AEA levels throughout the study. Although both groups initially had similar anxiety levels, 385 A carriers experienced a faster decline in anxiety. ...
Background
Major Depressive Disorder (MDD) and Alcohol Use Disorder (AUD) are two high-prevalent conditions where the Endocannabinoid system (ECS) is believed to play an important role. The ECS regulates how different neurotransmitters interact in both disorders, which is crucial for controlling emotions and responses to stress and reward stimuli. Measuring peripheral endocannabinoids (eCBs) in human serum and plasma can help overcome the limitations of detecting endocannabinoid levels in the brain. This systematic review aims to identify levels of peripheral eCBs in patients with MDD and/or AUD and find eCBs to use as diagnostic, prognostic biomarkers, and potential therapeutic targets.
Methods
We conducted a systematic literature search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines from the earliest manuscript until October 22, 2023, in three electronic databases. We included studies of human adults who had a current diagnosis of AUD and/or MDD and evaluated plasma or serum endocannabinoids. We carefully considered known variables that may affect endocannabinoid levels.
Results
We included 17 articles in this systematic review, which measured peripheral eCBs in 170 AUD and 359 MDD patients. Stressors increase peripheral 2-arachidonyl-glycerol (2-AG) concentrations, and 2-AG may be a particular feature of depression severity and chronicity. Anxiety symptoms are negatively correlated with anandamide (AEA) concentrations, and AEA significantly increases during early abstinence in AUD. Studies suggest a negative correlation between Oleoylethanolamide (OEA) and length of abstinence in AUD patients. They also show a significant negative correlation between peripheral levels of AEA and OEA and fatty acid amide hydrolase (FAAH) activity. Eicosapentaenoylethanolamide (EPEA) is correlated to clinical remission rates in depression. Included studies show known variables such as gender, chronicity, symptom severity, comorbid psychiatric symptoms, length of abstinence in the case of AUD, and stress-inducibility that can affect peripheral eCBs.
Conclusions
This systematic review highlights the important role that the ECS plays in MDD and AUD. Peripheral eCBs appear to be useful biomarkers for these disorders, and further research may identify potential therapeutic targets. Using accessible biological samples such as blood in well-designed clinical studies is crucial to develop novel therapies for these disorders.
... With mounting evidence supporting the role of endocannabinoids in modulating fear and stress through their dynamic synthesis and breakdown (Ahmed et al., 2022), we explored how the expression of ECS enzymes responds to fear and anxiety stimuli by subjecting snails to CE. This exposure led to a significant increase in LymFAAH mRNA levels in snails' central ring ganglia, indicating a crucial role for FAAH, the enzyme responsible for breaking down AEA, in adapting to anxiety and stress (Spagnolo et al., 2016). Consistently, FAAHdeficient transgenic mice exhibit less anxiety-like behavior (Moreira et al., 2008;Spagnolo et al., 2016). ...
... This exposure led to a significant increase in LymFAAH mRNA levels in snails' central ring ganglia, indicating a crucial role for FAAH, the enzyme responsible for breaking down AEA, in adapting to anxiety and stress (Spagnolo et al., 2016). Consistently, FAAHdeficient transgenic mice exhibit less anxiety-like behavior (Moreira et al., 2008;Spagnolo et al., 2016). As gene expression changes do not directly imply shifts in enzyme activity or protein abundance, further research is required to determine if predator-induced stress and anxiety could decrease AEA levels through enhanced LymFAAH activity. ...
... )-significantly increased the expression levels of LymDAGL and LymFAAH, while notably decreasing LymMAGL and LymNAPE-PLD mRNA levels in snails' central ring ganglia. In rodents, similar acute stress conditions lead to lowered AEA levels in the hippocampus, primarily through enhanced hydrolysis mediated by FAAH(Gunduz-Cinar, 2021;Spagnolo et al., 2016), along with a reduction in MAGL activity(Morena et al., 2016). Although future research is necessary to ascertain if these transcriptional changes in L. stagnalis correlate with decreased AEA signaling and a potential increase in 2-AG signaling, our findings remark on the importance of endocannabinoid signaling at multiple levels as a regulator of stress response and adaptation and underscore the conserved role of the ECS in the neurobiology of stress.Finally, in previous studies we found that administering 6.25 mg/kg of LPS has been shown to trigger an inflammatory response in L. stagnalis, affecting both immune-related targets and enzymes involved in the kynurenine pathway Rivi et al., under review). ...
The endocannabinoid system (ECS) plays an important role in neuroprotection, neuroplasticity, energy balance, modulation of stress, and inflammatory responses, acting as a critical link between the brain and the body's peripheral regions, while also offering promising potential for novel therapeutic strategies. Unfortunately, in humans, pharmacological inhibitors of different ECS enzymes have led to mixed results in both preclinical and clinical studies. As the ECS has been highly conserved throughout the eukaryotic lineage, the use of invertebrate model organisms like the pond snail Lymnaea stagnalis may provide a flexible tool to unravel unexplored functions of the ECS at the cellular, synaptic, and behavioral levels. In this study, starting from the available genome and transcriptome of L. stagnalis, we first identified putative transcripts of all ECS enzymes containing an open reading frame. Each predicted protein possessed a high degree of sequence conservation to known orthologues of other invertebrate and vertebrate organisms. Sequences were confirmed by qualitative PCR and sequencing. Then, we investigated the transcriptional effects induced by different stress conditions (i.e., bacterial LPS injection, predator scent, food deprivation, and acute heat shock) on the expression levels of the enzymes of the ECS in Lymnaea's central ring ganglia. Our results suggest that in Lymnaea as in rodents, the ECS is involved in mediating inflammatory and anxiety‐like responses, promoting energy balance, and responding to acute stressors. To our knowledge, this study offers the most comprehensive analysis so far of the ECS in an invertebrate model organism. image
... Blood was centrifuged at 4400 rpm for 20 min at 4°C; serum was removed and stored in 1.0 ml aliquots in plastic cryovials at −80°C until analysis. 2-AG and AEA concentrations were determined in lipid extracts of serum using isotope dilution, liquid chromatography-mass spectrometry following previously published methods [29]. Plasma cortisol levels were determined using commercially available radioimmunoassay (RIA) kits. ...
... The minority subgroup included individuals endorsing African American, Black, Hispanic, and Native American. The number in each group is Caucasian, non-Hispanic (CNH) men (57); CNH women (23); minority men (61), and minority women (29). Symbols represent the mean; vertical lines represent the SEM. ...
... There was no significant relationship between FAAH genotype and PTSD symptoms at either time point in minorities. As has been shown previously [29], individuals with A/A also had significantly greater circulating AEA concentrations. Thus, these results are consistent with our finding that circulating AEA concentrations are positively associated with PTSD severity. ...
The endocannabinoid signaling system (ECSS) regulates fear and anxiety. While ECSS hypoactivity can contribute to symptoms of established post-traumatic stress disorder (PTSD), the role of the ECSS in PTSD development following trauma is unknown. A prospective, longitudinal cohort study of 170 individuals (47% non-Hispanic Caucasian and 70% male) treated at a level 1 trauma center for traumatic injury was carried out. PTSD symptom assessments and blood were obtained during hospitalization and at follow-up (6–8 months post injury). Serum concentrations of the endocannabinoids N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) were determined at both time points and selected genetic polymorphisms in endocannabinoid genes, including rs324420 in fatty acid amide hydrolase, were assessed. For the entire sample, serum concentrations of AEA at hospitalization were significantly higher in those diagnosed with PTSD at follow-up (p = 0.030). Serum concentrations of 2-AG were significantly, positively correlated with PTSD symptom severity at follow-up only in minorities (p = 0.014). Minority participants (mostly Black/African American) also demonstrated significant, negative correlations between serum AEA concentrations and PTSD symptom severity both measured at hospitalization (p = 0.015). The A/A genotype at rs324420 was associated with significantly higher PTSD symptom severity (p = 0.025) and occurred exclusively in the Black participants. Collectively, these results are contrary to our hypothesis and find positive associations between circulating endocannabinoids and risk for PTSD. Minority status is an important modulator of the association between endocannabinoids and risk for PTSD, suggesting that the ECSS contributes to risk most significantly in these individuals and the contextual factors related to these findings should be further explored.
... Interestingly, administering a FAAH inhibitor is not the only way to examine the effects of elevated AEA on fear conditioning processesthere is also a fairly common functional single nucleotide polymorphism (SNP) in the FAAH gene (C385A; rs324420) that results in lower levels of FAAH protein, and as a result, increased AEA concentrations (Mayo et al., 2020a;Sipe et al., 2002;Spagnolo et al., 2016). Interestingly, individuals that possess the FAAH C385C → A mutation exhibit elevated AEA concentrations (due to lower FAAH expression) in the amygdala and enhanced fear extinction recall neurocircuitry (i.e., enhanced regulation of amygdala by ventromedial prefrontal cortex; vmPFC), which is in contrast to women with PTSD who typically exhibit altered fear extinction neurocircuitry (e.g., amygdala hyperreactivity, vmPFC and hippocampal hyporeactivity) and poor extinction learning (Mayo et al., 2021;Mayo et al., 2020a;Green et al., 2021). ...
... Interestingly, individuals that possess the FAAH C385C → A mutation exhibit elevated AEA concentrations (due to lower FAAH expression) in the amygdala and enhanced fear extinction recall neurocircuitry (i.e., enhanced regulation of amygdala by ventromedial prefrontal cortex; vmPFC), which is in contrast to women with PTSD who typically exhibit altered fear extinction neurocircuitry (e.g., amygdala hyperreactivity, vmPFC and hippocampal hyporeactivity) and poor extinction learning (Mayo et al., 2021;Mayo et al., 2020a;Green et al., 2021). Similar to FAAH inhibition, in addition to accelerated fear extinction learning (Dincheva et al., 2015), elevated AEA due to this genetic polymorphism has also been linked to decreased anxiety responses following the presentation of stress-and threat-inducing stimuli (Hariri et al., 2009) in healthy humans without a clinical anxiety disorder, and lower hyperarousal symptoms in adults with PTSD (Spagnolo et al., 2016). However, aside from one recent non-imaging investigation (Ney et al., 2021b), it remains relatively unknown whether potential genetic variations of this system (e.g., FAAH polymorphism) influence initial fear acquisition and extinction learning processes in adults with PTSD. ...
... Also, there were no differences in PTSD symptoms or symptom severity between groups. The only other study examining the influence of the FAAH C385A variant on PTSD symptoms reported significantly lower hyperarousal symptoms (but not avoidance, re-experiencing or PSTD severity symptoms) for AA/AC carriers, although it should be noted that study involved a smaller sample of treatment seeking men and women with a comorbid alcohol use disorder (Spagnolo et al., 2016). ...
Background:
Posttraumatic Stress Disorder (PTSD) is commonly treated with exposure-based cognitive therapies that are based on the principles of fear acquisition and extinction learning. Elevations in one of the major endocannabinoids (anandamide) either via inhibition of the primary degrading enzyme (fatty acid amide hydrolase; FAAH) or via a genetic variation in the FAAH gene (C385A; rs324420) has resulted in accelerated extinction learning and enhanced extinction recall among healthy adults. These results suggest that targeting FAAH may be a promising therapeutic approach for PTSD. However, these effects have not yet been comprehensively examined in a PTSD population.
Methods:
The current study examined whether genetic variation in the FAAH gene (CC [n = 49] vs AA/AC [n = 36] allele carriers) influences physiological (skin conductance), cognitive (threat expectancy), and neural (network and voxel-wise activation) indices of fear acquisition and extinction learning among a sample of adult women with PTSD (N = 85).
Results:
The physiological, cognitive, and neural signatures of fear acquisition and extinction learning varied as a function of whether or not individuals possess the FAAH C385A polymorphism. For instance, we report divergent responding between CC and AA/AC allele carriers to CS + vs CS- in limbic and striatum networks and overall greater activation throughout the task among AA/AC allele carriers in several regions [e.g., inferior frontal, middle frontal, parietal] that are highly consistent with a frontoparietal network involved in higher-order executive functions.
Conclusions:
These results suggest that genetic variation within the FAAH gene influences physiological, cognitive, and neural signatures of fear learning in women with PTSD. In order to advance our understanding of the efficacy of FAAH inhibition as a treatment for PTSD, future clinical trials in this area should assess genetic variation in the FAAH gene in order to fully depict and differentiate the acute effects of a drug manipulation (FAAH inhibition) from more chronic (genetic) influences on fear extinction processes.
... These effects are mediated by CB1R, such that blockade of CB1R results in impaired extinction, and restoration of this receptor rescues extinction (Kamprath et al., 2006;Marsicano et al., 2002). This effect appears to extend to human studies where peripheral levels of endocannabinoids (AEA, 2-AG, and the N-acyl-ethanolamide oleoylethanolamide) tend to be lower in individuals with higher PTSD symptom severity (Hill et al., 2013;Spagnolo et al., 2016;Wilker et al., 2016). Similarly, augmentation of endocannabinoid signaling in humans has resulted in improved fear extinction in some studies. ...
... (also known as c.385C>A or Pro129Thr, here called FAAH rs324420) have enhanced fear extinction learning and decreased anxiety levels compared to CC homozygotes (Dincheva et al., 2015;Gee et al., 2016;Gunduz-Cinar et al., 2013;Hariri et al., 2009;Spagnolo et al., 2016). This effect is particularly prominent in AA homozygotes and is likely driven by Pro129Thr conversion in this SNP resulting in a more easily degradable FAAH enzyme, yielding increased AEA levels in the carriers (Mayo et al., 2018;Sipe et al., 2002). ...
... Despite previous studies strongly supporting a positive role for the A allele of FAAH in fear extinction learning and extinction recall (Dincheva et al., 2015;Mayo et al., 2018), stress responding (Gunduz-Cinar et al., 2013;Spagnolo et al., 2016) and PTSD (Spagnolo et al., 2016), we found minimal effects of the polymorphism in our sample. During late extinction learning, we observed higher responses to the CS-in A carriers of the PTSD group. ...
Background
The endocannabinoid system is gaining increasing attention as a favorable target for improving posttraumatic stress disorder (PTSD) treatments. Exposure therapy is the gold-standard treatment for PTSD, and fear extinction learning is a key concept underlying successful exposure.
Methods
This study examined the role of genetic endocannabinoid polymorphisms in a fear extinction paradigm with PTSD compared to healthy participants (N = 220). Participants provided saliva for genotyping, completed a fear conditioning and extinction task, with blood samples taken before and after the task (n = 57). Skin conductance was the outcome and was analyzed using mixed models.
Results
Results for cannabinoid receptor type 1 polymorphisms suggested that minor alleles of rs2180619 and rs1049353 were associated with poorer extinction learning in PTSD participants. The minor allele of the fatty acid amide hydrolase (FAAH) polymorphism rs324420 was associated with worse extinction in PTSD participants. Subanalysis of healthy participants (n = 57) showed the FAAH rs324420 genotype effect was dependent on plasma arachidonoyl ethanolamide (AEA) level, but not oleoylethanolamide or 2-arachidonoyl glycerol. Specifically, higher but not lower AEA levels in conjunction with the minor allele of FAAH rs324420 were associated with better extinction learning.
Conclusions
These findings provide translational evidence that cannabinoid receptor 1 and AEA are involved in extinction learning in humans. FAAH rs324420's effect on fear extinction is moderated by AEA plasma level in healthy controls. These findings imply that FAAH inhibitors may be effective for targeting anxiety in PTSD, but this effect needs to be explored further in clinical populations.
... We extend prior research linking this genetic variant with enhanced eCB signaling, suggesting a neural mechanism that may predict differential development of fear-based disorders. Mayo, Asratian, Lindé, Holm, et al., 2020;Spagnolo et al., 2016). ...
... Recent work indicates that A-carriers exhibit elevated peripheral AEA as well as facilitated extinction learning and recall using a Pavlovian fear-potentiated startle paradigm (Mayo, Asratian, Lindé, Holm, et al., 2020). Clinical studies also implicate the FAAH A-allele in lower risk and severity of anxiety disorders, as it is linked to lower trait anxiety in healthy adults (Dincheva et al., 2015) and lower posttraumatic stress symptoms in patients with fear-based disorders (Spagnolo et al., 2016). In all, convergent evidence from preclinical and clinical models suggests that the FAAH A-allele may protect against vulnerability to fear-based disorders via enhanced AEA signaling and fear extinction learning (e.g., Gee et al., 2016). ...
... Functional imaging studies in healthy adults implicate the hippocampus in the recall of extinction learning (Kalisch et al., 2006;Milad, Wright, et al., 2007). The FAAH C385A allele increases eCB levels peripherally and in fear-related brain regions, and thus mimics exogenous activation of CB1R via THC (Mayo, Asratian, Lindé, Holm, et al., 2020;Spagnolo et al., 2016). In a similar Pavlovian conditioning paradigm in healthy adults, oral administration of THC increased hippocampus activation during extinction recall compared to placebo (Rabinak et al., 2014). ...
Poor fear extinction learning and recall are linked to the development of fear-based disorders, like posttraumatic stress disorder, and are associated with aberrant activation of fear-related neural circuitry. This includes greater amygdala activation during extinction learning and lesser hippocampal and ventromedial prefrontal cortex (vmPFC) activation during recall. Emerging data indicate that genetic variation in fatty acid amide hydrolase (FAAH C385A; rs324420) is associated with increased peripheral endocannabinoid (eCB) levels and lesser threat-related amygdala reactivity. Preclinical studies link increased eCB signaling to better extinction learning and recall, thus FAAH C385A may protect against the development of trauma-related psychopathology by facilitating extinction learning. However, how this FAAH variant affects fear extinction neural circuitry remains unknown. In the present study, we used a novel, immersive-reality fear extinction paradigm paired with functional neuroimaging to assess FAAH C385A effects on fear-related neural circuitry and conditioned fear responding (US expectancy ratings, subjective units of distress, and skin conductance responding) in healthy adults from an urban area (Detroit, MI; N = 59; C/C = 35, A-carrier = 24). We found lesser amygdala activation in A-allele carriers, compared to C/C homozygotes, during early extinction recall. Likewise, we found lesser dorsal anterior cingulate cortex and greater hippocampus activation in early extinction learning in A-carriers compared to C/C homozygotes. We found no effects of FAAH C385A on vmPFC activation or behavioral fear indices. These data support and extend previous findings that FAAH genetic variation, associated with increased eCB signaling and subsequent enhanced fear extinction, may predict individual differences in successful fear learning.
... For example, circulating levels of anandamide, one of the main eCB ligands, are significantly reduced in individuals with PTSD compared to both healthy controls and those exposed to trauma that did not develop PTSD 10 . Conversely, increased anandamide (AEA) levels have been associated with decreased anxiety in response to a stress-provoking experimental procedure and with reduced severity of hyperarousal symptoms in a sample of subjects with comorbid PTSD and alcohol use disorder 11 . In addition, pharmacological inhibition of fatty-acid amide hydrolase . ...
... The copyright holder for this preprint this version posted January 14, 2025. ; https://doi.org/10.1101/2025.01.13.25320467 doi: medRxiv preprint extinction of fear memories and improved fear extinction recall are all associated to an increase in AEA levels 11,12,[35][36][37] . ...
Background: Posttraumatic stress disorder (PTSD) is one of the most sex-polarized psychiatric disorder, with women exhibiting twice the prevalence of men. The biological mechanisms underlying this sex disparity are not fully understood. Growing evidence suggests that alterations of the stress-buffering endocannabinoid (eCB) system and heightened inflammation are central to PTSD pathophysiology and may contribute to sex-biases in PTSD risk and severity. Here, we examined sex-differences in levels of circulating eCBs and peripheral pro-inflammatory markers in a cohort of men and women with PTSD and non-psychiatric controls.
Methods: 88 individuals with PTSD and 85 sex- and age- matched controls (HC) were retrospectively selected from the Mass General Brigham Biobank. Serum was assayed to measure circulating eCBs [anandamide (AEA), 2-arachidonyl glycerol (2-AG), oleoylethanolamide (OEA), and arachidonic acid (AA] and inflammatory markers [interleukin-1β (IL-1β), IL-6, IL-8, IL-18, tumor necrosis factor-alpha (TNFα), and C-reactive Protein (CRP)]. Linear regression was used to predict differential abundance of each analyte by disease state (PTSD/HC) within the male and female subgroups. Two-sided t-tests with Benjamini-Hochberg correction were used to examine differences across subgroups. Analyses were repeated in those with comorbid major depressive disorder.
Results: Male PTSD patients showed a significant decrease in AEA, AA and OEA levels compared to male controls (p′s<.001) and to female subgroups (PTSD and HCs) (p<.001). In contrast, among females, PTSD patients showed elevated levels of IL-6 (p<.05) and IL-8 (p<.05). Both male and female PTSD patients exhibited an increase in TNFα concentrations (p<.05), compared to HCs. Similar results were obtained in the subgroup of individuals with comorbid MDD and after controlling for the FAAH 385A genotype.
Conclusions: Our findings show for the first time that decrease in eCB levels is absent in women with PTSD, who in turn exhibit a broader increase in inflammatory markers, thus suggesting that biological perturbations underlying PTSD may vary by sex.
... Further, this study found that FAAH inhibition was associated with significantly higher anandamide concentrations, which presumably was the driver of the reduction in stress reactivity (Mayo, Asratian, Lindé, Morena, et al., 2020). Spagnolo et al. (2016) tested the relationship between the FAAH C385A polymorphism and alcohol-related stress induction in PTSD patients. C385A allele carriers displayed lower subjective anxiety responses to an alcohol stress challenge and had higher serum anandamide levels. ...
... C385A allele carriers displayed lower subjective anxiety responses to an alcohol stress challenge and had higher serum anandamide levels. Further, C385A allele carriers were reported to have lower PTSD symptom severity, which primary centred around the arousal symptomology cluster (Spagnolo et al., 2016). ...
... Similarly, the rs1049353 minor allele was associated with increased rate of PTSD diagnosis in a moderate adult sample of 320 participants from Los Angeles, but not in a similar sample of 310 participants from Finland (Lu et al., 2008). In a small sample of 49 participants with comorbid PTSD and AUD, Spagnolo et al. (2016) found that participants with a minor allele (A, n ¼ 25) on the FAAH rs324420 SNP had significantly greater reductions in hyperarousal symptoms compared with C/C homozygotes overtime (30 days later) but no baseline differences in any symptoms. The A allele carriers also self-reported less anxiety in response to an acute alcohol-related stressor compared with C/C homozygotes (Spagnolo et al., 2016). ...
... In a small sample of 49 participants with comorbid PTSD and AUD, Spagnolo et al. (2016) found that participants with a minor allele (A, n ¼ 25) on the FAAH rs324420 SNP had significantly greater reductions in hyperarousal symptoms compared with C/C homozygotes overtime (30 days later) but no baseline differences in any symptoms. The A allele carriers also self-reported less anxiety in response to an acute alcohol-related stressor compared with C/C homozygotes (Spagnolo et al., 2016). This is what may have been predicted from the preclinical literature described above. ...
... 63 Converging evidence suggests some associations between alterations in the activity of the eCB system and emotional-motivational disorders, such as depression, addiction, and anxiety. 64,65 Other data shows that blocking the eCB system causes depressive behaviors in animal models. Conversely, administration of CB1 receptor agonists or eCB uptake inhibitors, or FAAH enzyme inhibitors results in antidepressant effects. ...
... 75 Spagnolo et al. revealed that the FAAH C385A reduces PTSDrelated stress response and symptom severity but increases reactivity toward unpleasant pictures. 64 However, Lazary et al. assessed the pathological effect of CBR2 R63Q and FAAH C385A (gene  gene interaction) on the depressive and anxious phenotype in childhood trauma and showed that these polymorphisms increased susceptibility to childhood trauma. 61 They showed that FAAH C385A interaction with dysfunctional CBR2 receptor (due to R63Q) can be anxiogenic through disrupted inhibition of both inflammation and the HPA axis at the same time. ...
The endocannabinoid (eCB) system is an important neuromodulatory system with its extensive network of receptors throughout the human body that has complex actions in the nervous system, immune system, and all of the body's other organs. Fatty acid amide hydrolase (FAAH) is an important membrane‐bound homodimeric degrading enzyme that controls the biological activity of N‐arachidonoylethanolamide (AEA) in the eCB system and other relevant bioactive lipids. It has been shown that several single nucleotide polymorphisms (SNPs) of FAAH are associated with various phenotypes and diseases including cardiovascular, endocrine, drug abuse, and neuropsychiatric disorders. A common functional and most studied polymorphism of this gene is C385A (rs324420), which results in the replacement of a conserved proline to threonine in the FAAH enzyme structure, leads to a reduction of the activity and expression of FAAH, compromises the inactivation of AEA and causes higher synaptic concentrations of AEA that can be associated with several various phenotypes. The focus of this review is on evidence‐based studies on the associations of the FAAH C385A polymorphism and the various diseases or traits. Although there was variability in the results of these reports, the overall consensus is that the FAAH C385A genotype can affect susceptibility to some multifactorial disorders and can be considered a potential therapeutic target.
... Endocannabinoids in human blood samples have been reported to show stress reactivity in several studies, however the methods for inducing stress have varied substantially (Chouker et al., 2010;Crombie et al., 2019;Dlugos et al., 2012;Mangieri et al., 2009;Mayo et al., 2020aMayo et al., ,2020bNey et al., 2021d;Spagnolo et al., 2016). Dlugos et al. (2012) examined serum endocannabinoid and cortisol concentrations of healthy participants before and after the TSST. ...
... Crombie and colleagues also showed a significant increase in circulating concentrations of 2-AG, following psychosocial stress (TSST) in healthy non-clinical participants, but not for those with a diagnosis of PTSD (Crombie et al., 2019). Paradigms using alcohol-related stress imagery scripts have found that alcoholic participants with PTSD who have minor alleles on the FAAH C385A polymorphism have decreased subjective stress responses compared to intact C385C carriers (Spagnolo et al., 2016). Similarly, compared to alcoholics who had no increase in AEA, social drinkers had significantly increased AEA blood levels following an alcohol imagery cueing task (Mangieri et al., 2009). ...
The endocannabinoid system is known to be involved in mechanisms relevant to PTSD aetiology and maintenance, though this understanding is mostly based on animal models of the disorder. Here we review how human paradigms can successfully translate animal findings to human subjects, with the view that substantially increased insight into the effect of endocannabinoid signalling on stress responding, emotional and intrusive memories, and fear extinction can be gained using modern paradigms and methods for assessing the state of the endocannabinoid system in PTSD.
... Initial human evidence supporting the therapeutic potential of FAAH inhibition comes from behavioral genetic studies. A FAAH 385C/A loss-of-function mutation encodes a FAAH protein that is degraded more rapidly, resulting in reduced FAAH activity and elevated peripheral AEA levels (48,(87)(88)(89). ...
... There is also evidence of stress-buffering effects of AEA in clinical populations. Individuals with PTSD and comorbid alcohol use disorder who carry the variant A-allele also have higher peripheral AEA levels (89). Moreover, they self-report less anxiety in response to a stress script and show greater improvements on the PTSD symptom of hyperarousal. ...
The endocannabinoid (eCB) system is one the most ubiquitous signaling systems of the brain and offers a rich pharmacology including multiple druggable targets. Preclinical research shows that eCB activity influences functional connectivity between the prefrontal cortex and amygdala, thereby influences an organism’s ability to cope with threats and stressful experiences. Animal studies show that cannabinoid receptor 1 (CB1) activation within the amygdala is essential for extinction of fear memories. Failure to extinguish traumatic memories is a core symptom of post-traumatic stress disorder, suggesting that potentiating eCB signaling may have a therapeutic potential in this condition. It has, however, been unknown whether animal findings in this domain translate to humans. Data to inform this critical question are now emerging and are the focus of this review.
We first briefly summarize the biology of the eCB system and the animal studies that support its role in fear extinction and stress responding. We then discuss the pharmacological eCB-targeting strategies that may be exploited for therapeutic purposes: Direct CB1 activation, using THC or its synthetic analogues; or indirect potentiation, through inhibition of eCB degrading enzymes, the anandamide (N-arachidonoylethanolamine; AEA) degrading enzyme fatty acid amide hydrolase (FAAH); or the 2-arachidonylglycerol degrading enzyme monoacylglycerol lipase. We then review recent human data on direct CB1 activation via THC and AEA potentiation through FAAH blockade. The available human data consistently support a translation of animal findings on fear memories and stress reactivity and suggest a potential therapeutic utility in humans.
... It is probable that genetic factors interact with the neurobiological effects of alcohol in shaping a person's susceptibility to particular withdrawal symptoms [9,10]. Variations in symptom profiles may result from polymorphisms that moderate the effect of alcohol on neurological systems associated with emotion, stress response, and reward processing [11,12]. Knowledge of these factors could aid in devising customized treatment plans that cater to the individual symptom experiences of patients, thereby boosting long-term remission rates. ...
Background
Alcohol dependence (AD) confers susceptibility to distressing withdrawal symptoms that often lead to relapse. While neuroadaptation during withdrawal influences symptoms, the genetic factors behind it have not been thoroughly investigated. We utilized propensity score matching and investigated connections between AD, OXT rs6133010, and withdrawal symptoms to address confounding variables. By elucidating the OXT rs6133010-AD interaction, we aim to gain insights into alcohol withdrawal variability and contribute to personalized treatment approaches.
Methods
A cross-sectional study design was employed involving a total of 389 AD patients and 184 healthy controls who were genotyped for the OXT rs6133010 polymorphism. Psychiatric symptoms were evaluated using standardized scales during early withdrawal. Propensity score matching mitigated age and education differences.
Results
A two-way ANOVA demonstrated a significant AD x OXT rs6133010 interaction effect on hostility and anxiety. Further analysis revealed that the regulatory impact of OXT rs6133010 was exclusively in AD patients. Specifically, AD patients with the AA homozygote showed robust protection against hostility and anxiety. Path analysis unveiled the underlying mechanism of OXT symptom regulation.
Conclusion
This study presents novel evidence that OXT rs6133010 specifically modulates psychiatric symptoms in AD. The G allele may heighten hostility and anxiety vulnerability during alcohol withdrawal. These findings emphasize considering environmental factors when studying and utilizing oxytocin therapeutically. Additionally, OXT may not directly act as an anxiolytic but instead regulates anxiety by modulating hostility.
... Despite the large number of preclinical studies demonstrating the critical role of eCB signaling in chronic alcohol abuse and withdrawal, only a few studies have investigated whether CNR1 gene variation contributes to the inherent predisposition to alcohol dependence [89e94]. Interestingly, in addition to the CNR1 gene, the FAAH C385A SNP [95,96] has been identified as a potential indicator of individuals who are at higher risk for alcohol abuse. Moreover, the FAAH Pro129Thr missense variant (rs324420) has also been reported to be associated with alcohol dependence severity in European Americans [97]. ...
... The hypothesis of changes in AEA prior to the onset of psychopathology is supported by data from a prospective cohort-study, that showed little within-person variation in AEA but a significant longitudinal between-person relationship between hair AEA and depressive symptoms in adults with depression [81]. Several studies investigating a functional polymorphism of the AEA-degrading enzyme FAAH (C385C-> A), which results in reduced FAAH activity and therefore higher AEA concentrations, have repeatedly shown that carriers with lower FAAH activity exhibit better stress or fear-related behavior [82], e.g., reduced subjective anxiety responses to a stress task [83], improved fear extinction [56] and more successful extinction recall [84]. A recent fMRI study demonstrated a positive association between higher AEA levels and greater neural activation during extinction learning [85] and Zabik et al. showed that FAAH (C385A) is associated with less amygdala activation during extinction recall showing resistance to stress induced changes in negative affect [56]. ...
Non-suicidal self-injury (NSSI) is a highly prevalent phenomenon in adolescence, often associated with prior traumatic experiences. The development and maintenance of NSSI is associated with dysregulation of the stress response, and evidence suggests that the hypothalamic-pituitary-adrenal (HPA) axis plays an important role. The endocannabinoid system is a neuromodulatory system in close functional interaction with the HPA axis. Several studies have reported alterations of the endocannabinoid system in adult patients with post-traumatic stress disorder. However, the role of the endocannabinoid system in children and adolescents with NSSI is less clear, and previously no study examined endocannabinoids in youth with experiences of maltreatment. N-arachidonyl ethanolamide (AEA) and 2-arachidonyl glycerol (2-AG) were quantified alongside sociodemographic and clinical characteristics in n = 148 adolescents (12–17 years of age). Analyses addressed group differences comparing healthy controls (HC, n = 38), patients with NSSI without (NSSI − CMT, n = 42) and with a history of childhood maltreatment (NSSI + CMT, n = 68). We show that AEA is reduced in adolescents with NSSI independent of childhood maltreatment. Further, we present first evidence for a negative association between AEA and NSSI frequency as well as AEA and the severity of childhood maltreatment. This is the first study providing evidence for alterations in the endocannabinoid system in children and adolescents engaging in repetitive NSSI. Findings from the study support current endocannabinoid-hypotheses on the neurobiology of trauma and adversity, extending existing findings of altered endocannabinoid signaling following exposure to traumatic events to a well-powered sample of children and adolescents.
... Interestingly, while changes in AEA content could not be detected concerning susceptibility, there was significant overexpression of Faah, the gene of fatty acid amid hydrolase (FAAH), the main degrading enzyme of AEA in the PrL of susceptible subjects in comparison to resilient individuals, suggesting that elevated FAAH activity is linked with a tendency to show trauma-induced fear generalization. This finding confirms that FAAH is involved in the manifestation of PTSD-related symptoms as carriers of C385A single nucleotide polymorphism in the FAAH gene resulting in less stable FAAH protein with decreased AEA degrading potency (Sipe et al., 2002) showed less intense symptoms (Crombie et al., 2022;Mayo et al., 2020;Spagnolo et al., 2016). Taken together, while our findings regarding no differences between resilient and susceptible subpopulations in brain AEA content are in contrast with literature findings, this is possibly explained by the source and the time point of sampling. ...
Traumatic experiences result in the development of posttraumatic stress disorder (PTSD) in 10–25% of exposed individuals. While human clinical studies suggest that susceptibility is potentially linked to endocannabinoid (eCB) signaling, neurobiological PTSD susceptibility factors are poorly understood. Employing a rat model of contextual conditioned fear, we characterized distinct resilient and susceptible subpopulations based on lasting generalized fear, a core symptom of PTSD. In these groups, we assessed i.) eCB levels by mass spectrometry and ii.) expression variations of eCB system- and iii.) neuroplasticity-related genes by real-time quantitative PCR in the circuitry relevant in trauma-induced changes. Furthermore, employing unsupervised and semi-supervised machine learning based statistical analytical models, we assessed iv.) gene expression patterns with the most robust predictive power regarding PTSD susceptibility. According to our findings, in our model, generalized fear responses occurred with sufficient variability to characterize distinct resilient and susceptible subpopulations. Resilient subjects showed elevated prelimbic and lower ventral hippocampal levels of eCB 2-arachidonoyl-glycerol (2-AG) compared to resilient and non-shocked control subjects. Ventral hippocampal 2-AG content positively correlated with the strength of fear generalization. Furthermore, susceptibility was associated with i.) prefrontal, hippocampal and amygdalar neuronal hypoactivity, ii.) marked decrease in the expression of genes of transcription factors modulating neuroplasticity and iii.) an altered expression pattern of eCB-related genes, including enzymes involved in eCB metabolism. Unsupervised and semi-supervised statistical approaches highlighted that hippocampal gene expression patterns possess strong predictive power regarding susceptibility. Taken together, the marked eCB and neuroplasticity changes in susceptible individuals associated with abnormal activity patterns in the fear circuitry possibly contribute to context coding deficits, resulting in generalized fear.
... In line with these findings, animal studies were able to demonstrate enhanced fear extinction processes when using a FAAH inhibitor [45]. Studies indicate lower anxiety levels in human A-allele carriers [28,43,46]. Recently, Mayo et al. (2018) have found that gene-dependent higher levels of AEA enhanced fear extinction and extinction recall, and that elevated AEA levels in AA-homozygotes have a protective function during human stress-related responses, in a way that A-allele homozygotes showed no significant decreases in AEA levels after a stress task [44]. ...
Borderline personality disorder (BPD) is a highly prevalent psychiatric disorder and presents a complex therapeutic challenge due to limited treatment modalities. Recent focus has converged on the endocannabinoid system (ECS) as a prospective modulator of psychopathological processes in BPD. To address this hypothesis, we analysed plasma endocannabinoid concentrations, specifically anandamide (AEA) and 2-arachidonoylglycerol (2-AG), in a cohort of 49 female BPD patients and 32 matched healthy controls (HC). Additionally, we examined the effect of the FAAH polymorphism rs324420 and correlates with psychopathology. The results indicate heightened AEA levels and, by trend, augmented 2-AG levels within the patient group, as compared to the HC group. Significant between group differences in AEA levels were evident in the CC genotype (FAAH_rs324420) but not in A-allele carriers while the commonly observed difference in AEA levels between A-allele carriers as compared to the CC genotype was not evident in patients. An effect of genotype was found with higher ratings of depression (Beck’s depression inventory, BDI-II) in the CC genotype compared to A-allele carriers (FAAH_rs32442), particularly in the patients. Significant alterations in AEA (and by trend in 2-AG) in patients with BPD may relate to compensatory ECS activity. The finding that the effect is most pronounced in CC homozygotes, might point towards a countermeasure to balance physiologically lower baseline AEA levels. The findings warrant further research to develop potentially beneficial psychopharmacological therapies.
... The sensitivity for cortisol assay was 57.5 pg/mL and no data lower than the minimum detection level were found. 2-AG and AEA concentrations were assayed in lipid extracts of the serum sample, using isotope dilution and liquid chromatographymass spectrometry as described previously [48]. eCBs were also measured in blood samples collected at T2 using the same procedures described above (range of blood collection times at T2 = 8.05 am to 6.05 pm, M = 12.09 pm). ...
... Our results in HC are, however, in line with literature studies in that we find a comparable magnitude of difference. For example, our results are similar in magnitude to those of Spagnolo et al. who find a robust effect of the FAAH genotype (~15-20%) in a small sample of participants with co-morbid posttraumatic stress disorder and alcohol use disorder [74]; with those of Mayo et al. who report 19% (p = 0.04) higher AEA in AC + AA [75] and with those of Sipe et al. who find 11% (p = 0.04) higher FAAH substrates in HC participants (n = 144; including participants with obesity) [66]. ...
Background:
Endocannabinoids and related N-acylethanolamines (NAEs) are bioactive lipids with important physiological functions and putative roles in mental health and addictions. Although chronic cannabis use is associated with endocannabinoid system changes, the status of circulating endocannabinoids and related NAEs in people with cannabis use disorder (CUD) is uncertain.
Methods:
Eleven individuals with CUD and 54 healthy non-cannabis using control participants (HC) provided plasma for measurement by high-performance liquid chromatography-mass spectrometry of endocannabinoids (2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (AEA)) and related NAE fatty acids (N-docosahexaenoylethanolamine (DHEA) and N-oleoylethanolamine (OEA)). Participants were genotyped for the functional gene variant of FAAH (rs324420, C385A) which may affect concentrations of AEA as well as other NAEs (OEA, DHEA).
Results:
In overnight abstinent CUD, AEA, OEA and DHEA concentrations were significantly higher (31-40%; p < 0.05) and concentrations of the endocannabinoid 2-AG were marginally elevated (55%, p = 0.13) relative to HC. There were no significant correlations between endocannabinoids/NAE concentrations and cannabis analytes, self-reported cannabis use frequency or withdrawal symptoms. DHEA concentration was inversely related with marijuana craving (r = -0.86; p = 0.001). Genotype had no significant effect on plasma endocannabinoids/NAE concentrations.
Conclusions:
Our preliminary findings, requiring replication, might suggest that activity of the endocannabinoid system is elevated in chronic cannabis users. It is unclear whether this elevation is a compensatory response or a predating state. Studies examining endocannabinoids and NAEs during prolonged abstinence as well as the potential role of DHEA in craving are warranted.
... Consistent with what has been found in the rodent literature, humans bearing the C385A FAAH SNP exhibit lower levels of trait anxiety, blunted reactivity of the amygdala in response to threat, increased functional and structural connectivity between the ventromedial prefrontal cortex and the amygdala and enhanced fear extinction (Demers, Drabant Conley, Bogdan, & Hariri, 2016;Dincheva et al., 2015;Gärtner et al., 2019;Gee et al., 2016;Green et al., 2021;Gunduz-Cinar et al., 2013;Hariri et al., 2009;Sisk et al., 2022;Zabik et al., 2022). Individuals with PTSD who possess this FAAH SNP also exhibit reduced symptoms of arousal and blunted stress-induced anxiety (Spagnolo et al., 2016), as well as enhanced treatment responses to virtual reality-assisted psychotherapy with D-cycloserine augmentation, particularly in those who have comorbid major depression and PTSD (Difede et al., 2022). As such, this represents a rare case of positive translation from basic science rodent studies to human subjects with genetic variance, where all the converging evidence indicates that elevations in AEA signaling confers some resilience to the effects of stress, particularly with respect to anxiety, and that these effects likely Psychological Medicine 7 relate to blunted neural activity in the amygdala (Mayo, Rabinak, Hill, & Heilig, 2022). ...
Cannabis is well established to impact affective states, emotion and perceptual processing, primarily through its interactions with the endocannabinoid system. While cannabis use is quite prevalent in many individuals afflicted with psychiatric illnesses, there is considerable controversy as to whether cannabis may worsen these conditions or provide some form of therapeutic benefit. The development of pharmacological agents which interact with components of the endocannabinoid system in more localized and discrete ways then via phytocannabinoids found in cannabis, has allowed the investigation if direct targeting of the endocannabinoid system itself may represent a novel approach to treat psychiatric illness without the potential untoward side effects associated with cannabis. Herein we review the current body of literature regarding the various pharmacological tools that have been developed to target the endocannabinoid system, their impact in preclinical models of psychiatric illness and the recent data emerging of their utilization in clinical trials for psychiatric illnesses, with a specific focus on substance use disorders, trauma-related disorders, and autism. We highlight several candidate drugs which target endocannabinoid function, particularly inhibitors of endocannabinoid metabolism or modulators of cannabinoid receptor signaling, which have emerged as potential candidates for the treatment of psychiatric conditions, particularly substance use disorder, anxiety and trauma-related disorders and autism spectrum disorders. Although there needs to be ongoing clinical work to establish the potential utility of endocannabinoid-based drugs for the treatment of psychiatric illnesses, the current data available is quite promising and shows indications of several potential candidate diseases which may benefit from this approach.
... These outcomes are consistent with the consequence of a persistently enhanced drive on PVN CRH neurons due to chronic disruption of eCB signalling. These data may also help to explain the low stress/anxiety phenotype seen in humans carrying a mutation in the FAAH gene, which results in reduced AEA metabolism and tonic elevations in eCB signalling (Dincheva et al., 2015;Gunduz-Cinar et al., 2013;Hariri et al., 2009;Mayo, Asratian, Lindé, Holm, et al., 2020;Spagnolo et al., 2016). Perhaps the basal elevations in eCB tone produced by this gene variant provide enhanced restriction of stress responsive neural circuits, centrally involving CRH neurons in the PVN. ...
Background and Purpose
Endocannabinoid (eCB) signalling gates many aspects of the stress response, including the hypothalamic–pituitary–adrenal (HPA) axis. The HPA axis is controlled by corticotropin releasing hormone (CRH) producing neurons in the paraventricular nucleus of the hypothalamus (PVN). Disruption of eCB signalling increases drive to the HPA axis, but the mechanisms subserving this process are poorly understood.
Experimental Approach
Using an array of cellular, endocrine and behavioural readouts associated with activation of CRH neurons in the PVN, we evaluated the contributions of tonic eCB signalling to the generation of a stress response.
Key Results
The CB1 receptor antagonist/inverse agonist AM251, neutral antagonist NESS243 and NAPE PLD inhibitor LEI401 all uniformly increased Fos in the PVN, unmasked stress‐linked behaviours, such as grooming, and increased circulating CORT, recapitulating the effects of stress. Similar effects were also seen after direct administration of AM251 into the PVN, while optogenetic inhibition of PVN CRH neurons ameliorated stress‐like behavioural changes produced by disruption of eCB signalling.
Conclusions and Implications
These data indicate that under resting conditions, constitutive eCB signalling restricts activation of the HPA axis through local regulation of CRH neurons in the PVN.
... Studies on stress-induced human psychopathologies further pinpoint an important role of AEA in the stress response. For example, the human C385A single-nucleotide polymorphism (SNP) in the Faah gene was studied with regards to pain insensitivity and elevated AEA levels [19], as well as in more moderate response to stress in posttraumatic stress disorder (PTSD) patients [20][21][22][23]. ...
Anandamide (AEA) is an endogenous ligand of the cannabinoid CB1 and CB2 receptors, being a component of the endocannabinoid signaling system, which supports the maintenance or regaining of neural homeostasis upon internal and external challenges. AEA is thought to play a protective role against the development of pathological states after prolonged stress exposure, including depression and generalized anxiety disorder. Here, we used the chronic social defeat (CSD) stress as an ethologically valid model of chronic stress in male mice. We characterized a genetically modified mouse line where AEA signaling was reduced by deletion of the gene encoding the AEA synthesizing enzyme N-acyl-phosphatidylethanolamine-hydrolyzing phospholipase D (NAPE-PLD) specifically in neurons activated at the time of CSD stress. One week after the stress, the phenotype was assessed in behavioral tests and by molecular analyses. We found that NAPE-PLD deficiency in neurons activated during the last three days of CSD stress led to an increased anxiety-like behavior. Investigating the molecular mechanisms underlying this phenotype may suggest three main altered pathways to be affected: (i) desensitization of the negative feedback loop of the hypothalamic-pituitary-adrenal axis, (ii) disinhibition of the amygdala by the prefrontal cortex, and (iii) altered neuroplasticity in the hippocampus and prefrontal cortex.
... Adding clinical relevance to these findings, individuals carrying the loss-of-function FAAH C385A allele exhibit both higher plasmatic levels of anandamide and improved recovery from experimentally induced anxiety (Spagnolo et al. 2016). Although our study did not investigate the effects of ARN14663 and ARN14280 on TMT-induced impairments of fear extinction (Schwendt et al. 2018;Shallcross et al. 2019), the robust anxiolytic-like responses produced by the compounds might be, at least in part, related to this process. ...
Background and aim
Post-traumatic stress disorder (PTSD), a chronic debilitating condition that affects nearly 5–10% of American adults, is treated with a handful of FDA-approved drugs that provide at best symptomatic relief and exert multiple side effects. Preclinical and clinical evidence shows that inhibitors of the enzyme fatty acid amide hydrolase (FAAH), which deactivates the endocannabinoid anandamide, exhibit anxiolytic-like properties in animal models. In the present study, we investigated the effects of two novel brain-permeable FAAH inhibitors – the compounds ARN14633 and ARN14280 – in a rat model of predator stress-induced long-term anxiety used to study PTSD.
Methods
We exposed male Sprague–Dawley rats to 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), a volatile constituent of fox feces, and assessed anxiety-like behaviors in the elevated plus maze (EPM) test seven days later. We measured FAAH activity using a radiometric assay and brain levels of FAAH substrates by liquid chromatography/tandem mass spectrometry.
Results
Rats challenged with TMT developed persistent (≥ 7 days) anxiety-like symptoms in the EPM test. Intraperitoneal administration of ARN14633 or ARN14280 1 h before testing suppressed TMT-induced anxiety-like behaviors with median effective doses (ED50) of 0.23 and 0.33 mg/kg, respectively. The effects were negatively correlated (ARN14663: R² = 0.455; ARN14280: R² = 0.655) with the inhibition of brain FAAH activity and were accompanied by increases in brain FAAH substrate levels.
Conclusions
The results support the hypothesis that FAAH-regulated lipid signaling serves important regulatory functions in the response to stress and confirm that FAAH inhibitors may be useful for the management of PTSD.
... Therefore, given that FAAH C385 results in reduced FAAH expression and activity and, thus, elevated AEA levels in the brain, the polymorphism might influence brain circuitry and function through immediate, phasic effects associated with the degradation of AEA and CB1 receptor signaling. This notion is backed up by a recent study showing that the A-allele is associated with (phasic) increased serum AEA levels throughout a stress challenge compared to C/C homozygotes, accompanied by a decreased subjective anxiety response to the stress challenge [82]. Furthermore, a recent PET study has shown that A-allele carriers show a longer in vivo binding of a FAAH labeling ligand, supporting the effect of this genetic variation on central FAAH levels [5]. ...
... Interestingly, studies in rodents have also reported that low FAAH is associated with reduced withdrawal-induced anxiety, convulsions, and ethanol-induced neurotoxicity (23,26,29,88) and with a diminished reaction to painful stimuli (75). Similarly, humans with lower FAAH have an attenuated experience of pain (89), have lower behavioral and neural responses to aversive stimuli (36,(90)(91)(92)(93)(94), and report less withdrawal from cannabis (78). Overall, our findings support the view that decreased FAAH activity might reduce sensitivity to aversive experiences. ...
Background
Reductions in fatty acid amide hydrolase (FAAH), the catabolic enzyme for the endocannabinoid anandamide, may play a role in drinking behavior and risk for alcohol use disorder (AUD). We tested the hypotheses that lower brain FAAH levels in heavy-drinking youth is related to increased alcohol intake, hazardous drinking and differential response to alcohol.
Methods
FAAH levels in striatum, prefrontal cortex and whole brain were determined using positron emission tomography imaging of [¹¹C]CURB in heavy-drinking youth (n=31; 19-25 years). C385A FAAH genotype (rs324420) was determined. Behavioral (n=29) and cardiovascular (n=22) responses to alcohol were measured during a controlled intravenous alcohol infusion.
Results
Lower [¹¹C]CURB binding was not significantly related to frequency of use but was positively associated with hazardous drinking and reduced sensitivity to the negative effects of alcohol. During alcohol infusion, lower [¹¹C]CURB binding related to greater self-reported stimulation and urges, and lower sedation (p<0.05). Lower heart rate variability was related to both greater alcohol-induced stimulation and lower [¹¹C]CURB binding (p<0.05). Family history of AUD (n=14) did not relate to [¹¹C]CURB binding.
Conclusions
In line with preclinical studies, lower FAAH in brain was related to a dampened response to negative, impairing effects of alcohol, increased drinking urges and alcohol-induced arousal. Lower FAAH might alter positive or negative effects of alcohol and increase urges to drink, thereby contributing to the addiction process. Determining whether FAAH influences motivation to drink through increased positive/arousing effects of alcohol or greater tolerance should be investigated.
... These outcomes are consistent with the consequence of a persistently enhanced drive on PVN CRH neurons due to chronic disruption of eCB signaling. These data may also help to explain the low stress/anxiety phenotype seen in humans carrying a mutation in the FAAH gene, which results in reduced AEA metabolism and tonic elevations in eCB signaling (Dincheva et al., 2015;Gunduz-Cinar et al., 2013;Hariri et al., 2009;Mayo et al., 2020a;Spagnolo et al., 2016). Perhaps the basal elevations in eCB tone produced by this gene variant provide enhanced restriction of stress responsive neural circuits, centrally involving CRH neurons in the PVN. ...
Endocannabinoid (eCB) signaling gates many aspects of the stress response, including the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is controlled by corticotropin-releasing hormone (CRH) producing neurons in the paraventricular nucleus of the hypothalamus (PVN). Disruption of eCB signaling increases drive to the HPA axis, but the mechanisms subserving this process are poorly understood. Using an array of cellular, endocrine, and behavioral readouts associated with the activation of CRH neurons in the PVN, we evaluated the contributions of tonic eCB signaling to the generation of a stress response. The CB1 receptor antagonist/inverse agonist AM251, neutral antagonist NESS243, and NAPE PLD inhibitor
LEI401 all uniformly increased c-fos in the PVN, unmasked stress-linked behaviors, such as grooming, and increased circulating CORT, recapitulating the effects of stress. Similar effects were also seen after direct administration of AM251 into the PVN, while optogenetic inhibition of PVN CRH neurons ameliorated stress-like behavioral changes produced by disruption of eCB signaling. These data indicate that under resting conditions, constitutive eCB signaling restricts activation of the HPA axis through local regulation of CRH neurons in the PVN.
... 89 Therefore, the elevated basal AEA levels and enhanced fear extinction in A allele carriers could become a protective factor against stressinduced negative effect, which may be beneficial in post-traumatic stress disorder (PTSD)-related treatment, and correspondingly, the A allele carriers with comorbid PTSD and alcohol use disorder (AUD) exhibited swifter decline of stress-induced anxiety response. 90,91 Conversely, higher AEA levels in rs324420 SNP may heighten reward-related ventral striatal reactivity and self-reported impulsivity plausibly through the CB1mediated dopaminergic pathway, which were significant risk factors for an addiction problem. 76,88 These premises were supported by the result of PET study in humans and autoradiography in knockin mice, of which A allele carriers had higher binding of dopamine receptors in D3-rich brain areas, that is, limbic stria-tum, globus pallidus, and ventral pallidum (in humans), and islands of Calleja (in mice). ...
Introduction: Fatty acid amide hydrolase (FAAH) is one of the main terminating enzymes of the endocannabinoid system (ECS). Since being discovered in 1996, the modulation of FAAH has been viewed as a compelling alternative strategy to obtain the beneficial effect of the ECS. With a considerable amount of FAAH-related publication over time, the next step would be to comprehend the proximity of this evidence for clinical application. Objective: This review intends to highlight the rationale of FAAH modulation and provide the latest evidence from clinical studies. Methods: Publication searches were conducted to gather information focused on FAAH-related clinical evidence with an extension to the experimental research to understand the biological plausibility. The subtopics were selected to be multidisciplinary to offer more perspective on the current state of the arts. Discussion: Experimental and clinical studies have demonstrated that FAAH was highly expressed not only in the central nervous system but also in the peripheral tissues. As the key regulator of endocannabinoid signaling, it would appear that FAAH plays a role in the modulation of mood and emotional response, reward system, pain perception, energy metabolism and appetite regulation, inflammation, and other biological processes. Genetic variants may be associated with some conditions such as substance/alcohol use disorders, obesity, and eating disorder. The advancement of functional neuroimaging has enabled the evaluation of the neurochemistry of FAAH in brain tissues and this can be incorporated into clinical trials. Intriguingly, the application of FAAH inhibitors in clinical trials seems to provide less striking results in comparison with the animal models, although some potential still can be seen. Conclusion: Modulation of FAAH has an immense potential to be a new therapeutic candidate for several disorders. Further exploration, however, is still needed to ensure who is the best candidate for the treatment strategy.
... The sensitivity for cortisol assay was 57.5 pg/mL and no data lower than the minimum detection level were found. 2-AG and AEA concentrations were assayed in lipid extracts of the serum sample, using isotope dilution and liquid chromatographymass spectrometry as described previously [48]. eCBs were also measured in blood samples collected at T2 using the same procedures described above (range of blood collection times at T2 = 8.05 am to 6.05 pm, M = 12.09 pm). ...
... In line with these findings, animal studies were able to demonstrate enhanced extinction processes when using cannabinoid agonists or FAAH inhibitors [12][13][14]. Studies point towards beneficial effects for human carriers of the homozygote AA and the heterozygote AC type regarding anxiety processing [7,15,16]. Recently, Mayo et al. [8] have found that gene-dependent higher levels of AEA in humans enhanced fear extinction and extinction recall, and that elevated AEA levels in AA homozygous carriers have a protective function during stress-related responses, in a way that AA homozygotes showed no significant decreases in AEA levels after a stress task. However, this effect was not observed for AC heterozygotes [8]. ...
Gold standard treatments for anxiety- and trauma-related disorders focus on exposure therapy promoting extinction learning and extinction retention. However, its efficacy is limited. Preclinical and particularly animal research has been able to demonstrate that homozygosity for the fatty acid amide hydrolase ( FAAH) C385A allele, similar to FAAH inhibition, is associated with elevated concentrations of anandamide (AEA) and facilitates extinction learning and extinction recall. However, in humans, the underlying neurobiological processes are less well understood, and further knowledge might enhance the development of more effective therapies. In this functional magnetic resonance imaging (fMRI) study, a fear conditioning, fear extinction and extinction recall paradigm was conducted with 55 healthy male adults. They were genotyped for the FAAH single-nucleotide polymorphism (SNP) rs324420 to investigate differences related to extinction recall in neural activation and State–Trait Anxiety Inventory (STAI) ratings between AC heterozygotes and CC homozygotes ( FAAH C385A SNP). Differential brain activation upon an unextinguished relative to an extinguished stimulus, was greater in AC heterozygotes as compared to CC homozygotes in core neural structures previously related to extinction recall, such as the medial superior frontal gyrus, the dorsal anterior cingulate and the anterior and middle insular cortex. Furthermore, AC heterozygotes displayed higher AEA levels and lower STAI-state ratings. Our data can be interpreted in line with previous suggestions of more successful extinction recall in A-allele carriers with elevated AEA levels. Data corroborate the hypothesis that the endocannabinoid system, particularly AEA, plays a modulatory role in the extinction of aversive memory.
... For example, higher plasma AEA and OEA levels are observed in women who deliver prematurely [10] and higher cannabinoid receptor mRNA is observed in peripheral blood mononuclear cells of women with polycystic ovary syndrome compared to controls [11]. Lower plasma endocannabinoid levels have been reported in posttraumatic stress disorder (PTSD) [12], and endocannabinoid genotypes that result in lower AEA degradation are associated with lower PTSD symptomology [13]. Blood measures are advantageous as they measure acute circulating analyte levels, whereas genetic sampling can provide indicators of long-term risk factors of a certain system. ...
Understanding the role of endogenous cannabinoids (endocannabinoids) in disease is of increasing importance. However, tools to investigate endocannabinoid levels in humans are limited. In the current study, we report a simplified sample preparation method for quantifying endocannabinoids and steroid hormones in hair using liquid-liquid extraction combined with ultra performance liquid chromatography coupled to tandem mass spectrometry. The fully validated method is at least R² = 0.99 linear between 5 and 1,000 pg/mg for each analyte and the detection limits are at or below 0.50 pg/mg for cortisol, progesterone, oleoylethanolamide, and arachidonoyl ethanolamide, and 2.65 pg/mg for 2-arachidonoyl glycerol. Sequential extraction of hair samples revealed that multiple extractions may be required for quantitative recovery of steroids. However endogenous cannabinoids were efficiently recovered using a single sample extraction. The method was applied to a psychosocial stress study where participants provided samples of both hair and saliva. Endogenous hair arachidonoyl ethanolamide levels were negatively associated with resting, but not stressed, salivary cortisol levels in healthy participants. This simplified method enables the detailed study of hormonal and endocannabinoids in human hair with high sensitivity.
... A genetic polymorphism in the human gene encoding FAAH is implicated in the dysregulation of FAAH-mediated AEA hydrolysis. This drives to a peculiar endophenotype that is associated with reduced index of trait anxiety and enhanced cortico-amygdala connectivity (40,41). Clinical studies also show the involvement of an abnormal function of the endocannabinoid system in suicide subjects. ...
Diagnostic precision, prediction and prevention of psychiatric disorders, including major unipolar depression, post-traumatic stress disorder (PTSD) and suicide ideation and attempts, remain underdeveloped areas in psychiatry given a general lack of biomarker assessment in the field. This makes the unmet goal of developing a precision medicine for these debilitating conditions an urgent necessity of neuropsychopharmacology research. Indeed, it is anticipated that biomarker discovery will tremendously enhance refinement of individualized medicine that currently rely on subjective symptom assessment based on the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-V).Developing reliable biomarkers entails the promise of predicting the best treatments for subjects that are more likely to respond to an individually-designed rather than to a "one-fit-all" treatment.Biomarker discovery will also enhance diagnostic evaluation of patients who suffer from psychiatric disorders that share a large symptom overlap and prevalent disorder comorbidity. In recent years, several novel biomarker candidates for mood disorders have been suggested (reviewed in Aspesi and Pinna, 2018). The endocannabinoid system has received much interest owing its role in several physiological and pathophysiological functions, including regulation of emotional behavior, cognitive processes, inflammation, chronic pain, epilepsy, and in general, its role underlying neuropsychiatric disorders (Marco et al., 2011;Marsicano et al., 2002).This opinion article will focus on the intriguing role of the endocannabinoid system in the regulation of affective disorders, specifically on major depressive disorders, PTSD and suicide behaviors. Furthermore, it will analyze whether data gathered in this exciting area of psychiatric research entails new leads in establishing novel biomarkers for these debilitating and prevalent psychiatric conditions that affect millions worldwide.
Gene variation linked to physiological functions is recognised to affect elite athletic performance by modulating training and competition-enabling behaviour. The fatty acid amide hydrolase (FAAH) has been investigated as a good candidate for drug targeting, and recently, its single-nucleotide polymorphism (SNP) rs324420 was reported to be associated with athletic performance. Given the implications, the biological pathways of this genetic polymorphism linked to elite athletic performance, considering sport type, psychological traits and sports injuries, need to be dissected. Thus, a narrative review of the literature concerning the biological mechanisms of this SNP was undertaken. In addition to its role in athletic performance, FAAH rs324420 is also involved in important mechanisms underlying human psychopathologies, including substance abuse and neural dysfunctions. However, cumulative evidence concerning the C385A variant is inconsistent. Therefore, validation studies considering homogeneous sports modalities are required to better define the role of this SNP in elite athletic performance and its impact on stress coping, pain regulation and inflammation control.
Cannabinoids (CBDs) represent a group of C21 or C22 terpenophenolic compounds predominantly produced by Cannabis but have also been found in plants from the Radula and Helichrysum genera. There are about 100 different cannabinoids, although some of them are metabolites. They are generally classified into ten subclasses [1–3].
This volume explores the latest experimental techniques in animal models of PTSD and humans affected by PTSD. The methods discussed in this book cover topics such as translational research; addressing sex differences; highlighting the state-of-the-art of biomarker discovery in the development and maintenance of PTSD; and looks at new promising agents to enhance fear extinction retention that may help millions of individuals that suffer from this debilitating disorder worldwide. In the Neuromethods series style, chapters include the kind of detail and key advice from the specialists needed to get successful results in your laboratory.
Post-traumatic stress disorder is associated with highly threatening and stressful events. The underlying memory is overconsolidated, leading to generalized fear expression and overall resistance to extinction- and reconsolidation-based interventions. Fear conditioning and avoidance protocols commonly used in laboratory settings induce specific and moderate-intensity aversive memories, but traumatic ones differ in quantitative and qualitative aspects. It would be appropriate to reproduce their abnormal features for studying PTSD neurobiology and assessing potential new therapeutics. After discussing the mnemonic basis of PTSD, its memory-related symptoms, and neurochemical findings underlying the traumatic memory, we aimed to review and discuss studies addressing the abovementioned question in rats and mice. Because of its potential translational value, the focus was on procedures associating an aversive task with single or combined post-training pharmacological interventions. Nearly 200 studies published since 1975 report that this protocol enhances aversive memory strength. The parallel assessment of abnormal features related to traumatic memories, such as altered specificity and susceptibility to extinction and drug-induced reconsolidation blockade, started more recently. Systemically administered drugs potentiating noradrenergic or glucocorticoid mechanisms have predominated, probably because of PTSD’s physiopathology. Other options and discrete brain infusions have provided complementary information. Currently available data indicate that aversive task exposure followed by adequate drug interference during consolidation generates more intense and generalized memories, which are less prone to modulation by behavioral and pharmacological strategies. These findings based on the bedside-to-bench approach are instructive for future analyses to advance our understanding of the underlying neurobiological mechanisms and develop more effective treatments for PTSD.Key wordsMemory consolidationTranslational researchPTSD model
Adverse situations that challenge an individual’s physical or psychological integrity are frequent throughout the lifespan. However, some situations go beyond the adaptive capacity and are considered traumatic, leading, in some individuals, to the development of post-traumatic stress disorder (PTSD), a condition characterized by persistent recollection of the trauma, avoidance of trauma-related cues, increased arousal, and fear generalization and sensitization. Some of these symptoms indicate that fear conditioning (cue or context-based) plays a major role in this disorder. Because individual variability is a major feature of PTSD, it is crucial to understand the psychological and biological factors that confer vulnerability and resilience to the development of this disorder. Animal models based on fear conditioning, which incorporates individual variability and sex differences, could, therefore, increase the translational value and validity of these models for testing of potential pharmacological and non-pharmacological treatments. In the present chapter, we will present the behavioral and neurobiological outcomes of animal models of PTSD based on paradigms of fear conditioning and the putative systems that may be involved with vulnerability and resilience. We will close the chapter by presenting the gaps in the literature and propose future directions on how to fill them in.Key wordsTraumatic stressAnimal modelsFear conditioningBehaviorFear extinctionIndividual variability
Post-traumatic stress disorder (PTSD) and other stress-related mood disorders are a major public health burden. Psychotherapy and SSRIs, the only pharmacological treatment currently approved for PTSD, are only partially treatments. Validated PTSD animal models could provide a better understanding of PTSD neurobiology via discovery of new pharmacologic targets to facilitate resilience after trauma. However, the complexity of PTSD makes the development of adequate animal models a challenge. To mimic the endophenotypes underlying the pathophysiology of PTSD, several trauma-focused rodent models have been assessed. The protracted social isolation paradigm used in our laboratory results in a time-dependent reduction in the synthesis of neurosteroids, such as allopregnanolone and its isomer, pregnanolone, which is consistent with PTSD clinical findings. Neurosteroids act at membrane receptors to regulate neuronal excitability and the stress response. Neurosteroids, allopregnanolone and pregnanolone are potent positive allosteric modulators of extrasynaptic GABAA receptors. Several alterations in the GABAergic system, both in GABA levels and GABAA receptor subunit composition, have been shown in PTSD. Following social isolation, changes in GABAergic receptor sensitivity and receptor conformation have been observed in corticolimbic areas that correlate with receptor pharmacology changes, and relative lack of sensitivity to anxiolytic benzodiazepines. Allopregnanolone plays a crucial role in the pathophysiology of PTSD and depression, mainly by potentiating GABAergic neurotransmission. Several agents have recently been shown to mimic the pharmacology of GABAergic neurosteroids and offer novel treatments for PTSD. In a translational approach, allopregnanolone, allopregnanolone analogs, SSRIs at low doses, and the endocannabinoid-like molecule, N-palmitoylethanolamine (PEA) have been shown to stimulate allopregnanolone biosynthesis and be effective in reducing PTSD-like behavioral alterations in rodent stress models and thus, provide potential candidates for clinical testing.
It is hard to overestimate the influence of the endocannabinoid signaling (ECS) system on central nervous system (CNS) function. In the 40 years since cannabinoids were found to trigger specific cell signaling cascades, studies of the ECS system continue to cause amazement, surprise, and confusion! CB1 cannabinoid receptors are expressed widely in the CNS and regulate cell-cell communication via effects on the release of both neurotransmitters and gliotransmitters. CB2 cannabinoid receptors are difficult to detect in the CNS but seem to "punch above their weight" as compounds targeting these receptors have significant effects on inflammatory state and behavior. Positive and negative allosteric modulators for both receptors have been identified and examined in preclinical studies. Concentrations of the endocannabinoid ligands, N-arachidonoylethanolamine and 2-arachidonoylglycerol (2-AG), are regulated by a combination of enzymatic synthesis and degradation and inhibitors of these processes are available and making their way into clinical trials. Importantly, ECS regulates many essential brain functions, including regulation of reward, anxiety, inflammation, motor control, and cellular development. While the field is on the cusp of preclinical discoveries providing impactful clinical and therapeutic insights into many CNS disorders, there is still much to be learned about this remarkable and versatile modulatory system.
Chronic tobacco exposure can alter the endocannabinoid (eCB) system, consequently leading to an anxiety state. In this study, we investigated the effects of waterpipe tobacco smoke (WTS) on cannabinoid receptor 1 and 2 (CBR1 and CBR2) gene and protein expression in mesocorticolimbic brain regions. Using elevated plus maze (EPM) and open field (OF) tests, the effects of WTS exposure on withdrawal-induced anxiety-like behavior were examined. The effect of ceftriaxone (CEF), a β-lactam known to upregulate glutamate transporter 1 (GLT-1), on anxiety and the expression of cannabinoid receptors was also determined. Male Sprague-Dawley rats were randomly assigned to four groups: 1) the Control group was exposed only to standard room air; 2) the WTS group was exposed to tobacco smoke and treated with saline vehicle; 3) the WTS-CEF group was exposed to WTS and treated with ceftriaxone; and 4) the CEF group was exposed only to standard room air and treated with ceftriaxone. Rats were exposed to WTS (or room air) for two hours per day, five days per week for a period of four weeks. Behavioral tests (EPM and OF) were conducted weekly during acute withdrawal, 24 h following WTS exposure. Rats were given either saline or ceftriaxone (200 mg/kg i.p.) for five days during Week 4, 30 min prior to WTS exposure. Withdrawal-induced anxiety was induced by WTS exposure but was reduced by ceftriaxone treatment. WTS exposure decreased CBR1 mRNA and protein expression in the NAc and VTA, but not PFC, and ceftriaxone treatment attenuated these effects. WTS exposure did not change CBR2 mRNA expression in the NAc, VTA, or PFC. These findings demonstrate that WTS exposure dysregulated the endocannabinoid system and increased anxiety-like behavior, and these effects were reversed by ceftriaxone treatment, which suggest the involvement of glutamate transporter 1 in these effects.
Borderline personality disorder (BPD) and antisocial personality disorder (ASPD) are the two most frequently diagnosed and researched DSM-5 personality disorders, and both are characterized by high levels of trait neuroticism. Fatty acid amide hydrolase (FAAH), an enzyme of the endocannabinoid system (ECS), has been linked to regulation of mood through modulation of anandamide, an endocannabinoid. We hypothesized that prefrontal cortex (PFC) FAAH binding would relate to trait neuroticism in personality disorders. Thirty-one individuals with personality disorders (20 with BPD and 11 with ASPD) completed the investigation. All participants completed the revised NEO Personality Inventory, which yields standardized scores (e.g., T scores) for the traits of neuroticism, openness, conscientiousness, agreeableness, and extraversion. All participants were medication free and were not utilizing illicit substances as determined by drug urinalysis. Additionally, none of the participants had a comorbid major depressive episode, bipolar disorder, psychotic disorder, or substance use disorder. Each participant underwent one [ ¹¹ C]CURB PET scan. Consistent with our hypothesis, neuroticism was positively correlated with PFC FAAH binding ( r = 0.42, p = 0.021), controlling for genotype. Neuroticism was also positively correlated with dorsal putamen FAAH binding ( r = 0.53, p = 0.0024), controlling for genotype. Elevated brain FAAH is an endophenotype for high neuroticism in BPD and ASPD. Novel pharmacological therapeutics that inhibit FAAH could emerge as potential new treatments for BPD and ASPD with high neuroticism.
Background: The Covid-19 pandemic caused great stress, especially for health workers which resulted in moderate or severe symptoms of depression, anxiety, insomnia, and more serious stress. Gender is very influential, given the differences in biological and social roles between men and women. Gender differences between men and women allow for variations in strategies in responding to mental health to increase awareness and self-management, so as to avoid mental health problems during the Covid-19 pandemic.
Subjects and Method: Meta-analysis was performed by searching articles from Google Scholar, PubMed, Scopus, Springer Link, and health-related databases. The keywords used in the article search were "health workers" AND "covid-19" AND "mental health". The inclusion of the criteria in this study is a full-text article, from 2019-2021, with a study design cross-sectional. The article analysis was carried out using RevMan 5.3.
Results: There were 5 articles analyzed, the results showed no significant difference between gender and mental health responses among health workers during the Covid-19 pandemic (aOR= 1.12; 95% CI= 0.59-2.13; p=0.01).
Conclusion: Not significant between primary studies regarding gender differences in mental health responses to health workers during the Covid-19 pandemic.
Keywords: health workers, covid-19, mental health
Correspondence: Riyesti Hero Fresna, Purwantoro Special Educational School. Wonogiri Regency, Central Java 57695. E-mail: riyestiherofresna01@gmail.com. Mobile +6281227831443.
Journal of Health Policy and Management (2021), 06(02): 130-138
https://doi.org/10.26911/thejhpm.2021.06.02.05
Purpose: Recent research has suggested that chronic alcohol exposure induces changes in the endocannabinoid system within the central nervous system and therefore could be an attractive target for better understanding and treating alcohol use disorder (AUD). Much of this research has centered around the CB1 receptor and its endogenous partial agonist, the endocannabinoid anandamide, as the CB1 receptor is densely expressed in brain regions involved in development and maintenance of addictive behaviors. In addition, recent evidence has suggested that chronic alcohol exposure induces changes in the modulation of endocannabinoid concentration and suggests that these changes may contribute to the motivation to abuse alcohol. Therefore, we performed a systematic literature review to evaluate how fatty acid amide hydrolase (FAAH), an enzyme that degrades anandamide, relates to the characteristics and biology of AUD, as well as how modulating FAAH through pharmacologic inhibition or genetic manipulation affects outcomes related to alcohol use and consumption. Method: A search strategy was developed using the terms "endocannabinoids" or "drug delivery systems" and "alcohol dependence" or "alcohol use disorder" or "alcoholism" and "Fatty Acid Amide Hydrolase" and "FAAH" as text words and Medical Subject Headings (i.e., MeSH and EMTREE). We then used this search strategy on the electronic databases PubMed, Embase, and Web of Science. Results: We found 224 records; after removing repeated records (37%), articles that did not fit the topic question (47%), or were not primary research (4%), we included 26 for qualitative synthesis (12%). Discussion: The literature clearly suggests that FAAH has a role in the biology and characteristics of AUD. FAAH inhibition seems especially promising as a target for alcohol withdrawal as it may lead to a reduction in symptoms, including anxiety and a reduction of alcohol intake reinstatement. However, decreased FAAH may also lead to reduced sensitivity to alcohol along with increased preference and intake. Conclusions: Modulation of FAAH is promising for therapeutic intervention of AUD, but requires more research. Pre-clinical studies have indicated that FAAH inhibition may reduce withdrawal characteristics, but may also exacerbate other characteristics of AUD outside of that period.
The common functional single-nucleotide polymorphism (rs324420, C385A) of the endocannabinoid inactivating enzyme fatty acid amide hydrolase (FAAH) has been associated with anxiety disorder relevant phenotype and risk for addictions. Here, we tested whether the FAAH polymorphism affects in vivo binding of the FAAH positron emission tomography (PET) probe [(11)C]CURB ([(11)C-carbonyl]-6-hydroxy-[1,10-biphenyl]-3-yl cyclohexylcarbamate (URB694)). Participants (n=24) completed one [(11)C]CURB/PET scan and were genotyped for rs324420. Relative to C/C (58%), A-allele carriers (42%) had 23% lower [(11)C]CURB binding (λk3) in brain. We report evidence that the genetic variant rs324420 in FAAH is associated with measurable differences in brain FAAH binding as per PET [(11)C]CURB measurement.Journal of Cerebral Blood Flow & Metabolism advance online publication, 3 June 2015; doi:10.1038/jcbfm.2015.119.
In human addicts, drug relapse and craving are often provoked by stress. Since 1995, this clinical scenario has been studied using a rat model of stress-induced reinstatement of drug seeking. Here, we first discuss the generality of stress-induced reinstatement to different drugs of abuse, different stressors, and different behavioral procedures. We also discuss neuropharmacological mechanisms, and brain areas and circuits controlling stress-induced reinstatement of drug seeking. We conclude by discussing results from translational human laboratory studies and clinical trials that were inspired by results from rat studies on stress-induced reinstatement. Our main conclusions are: (1) The phenomenon of stress-induced reinstatement, first shown with an intermittent footshock stressor in rats trained to self-administer heroin, generalizes to other abused drugs, including cocaine, methamphetamine, nicotine, and alcohol, and is also observed in the conditioned place preference model in rats and mice. This phenomenon, however, is stressor-specific and not all stressors induce reinstatement of drug seeking. (2) Neuropharmacological studies indicate the involvement of corticotropin-releasing factor (CRF), noradrenaline, dopamine, glutamate, kappa/dynorphin, and several other peptide and neurotransmitter systems in stress-induced reinstatement. Neuropharmacology and circuitry studies indicate the involvement of CRF and noradrenaline transmission in bed nucleus of stria terminalis and central amygdala, and dopamine, CRF, kappa/dynorphin, and glutamate transmission in other components of the mesocorticolimbic dopamine system (ventral tegmental area, medial prefrontal cortex, orbitofrontal cortex, and nucleus accumbens). (3) Translational human laboratory studies and a recent clinical trial study show the efficacy of alpha-2 adrenoceptor agonists in decreasing stress-induced drug craving and stress-induced initial heroin lapse.
Cross-species studies enable rapid translational discovery and produce the broadest impact when both mechanism and phenotype are consistent across organisms. We developed a knock-in mouse that biologically recapitulates a common human mutation in the gene for fatty acid amide hydrolase (FAAH) (C385A; rs324420), the primary catabolic enzyme for the endocannabinoid anandamide. This common polymorphism impacts the expression and activity of FAAH, thereby increasing anandamide levels. Here, we show that the genetic knock-in mouse and human variant allele carriers exhibit parallel alterations in biochemisty, neurocircuitry and behaviour. Specifically, there is reduced FAAH expression associated with the variant allele that selectively enhances fronto-amygdala connectivity and fear extinction learning, and decreases anxiety-like behaviours. These results suggest a gain of function in fear regulation and may indicate for whom and for what anxiety symptoms FAAH inhibitors or exposure-based therapies will be most efficacious, bridging an important translational gap between the mouse and human.
Corticotropin-releasing hormone (CRH) is a central integrator in the brain of endocrine and behavioral stress responses, whereas activation of the endocannabinoid CB1 receptor suppresses these responses. Although these systems regulate overlapping functions, few studies have investigated whether these systems interact. Here we demonstrate a novel mechanism of CRH-induced anxiety that relies on modulation of endocannabinoids. Specifically, we found that CRH, through activation of the CRH receptor type 1 (CRHR1), evokes a rapid induction of the enzyme fatty acid amide hydrolase (FAAH), which causes a reduction in the endocannabinoid anandamide (AEA), within the amygdala. Similarly, the ability of acute stress to modulate amygdala FAAH and AEA in both rats and mice is also mediated through CRHR1 activation. This interaction occurs specifically in amygdala pyramidal neurons and represents a novel mechanism of endocannabinoid-CRH interactions in regulating amygdala output. Functionally, we found that CRH signaling in the amygdala promotes an anxious phenotype that is prevented by FAAH inhibition. Together, this work suggests that rapid reductions in amygdala AEA signaling following stress may prime the amygdala and facilitate the generation of downstream stress-linked behaviors. Given that endocannabinoid signaling is thought to exert "tonic" regulation on stress and anxiety responses, these data suggest that CRH signaling coordinates a disruption of tonic AEA activity to promote a state of anxiety, which in turn may represent an endogenous mechanism by which stress enhances anxiety. These data suggest that FAAH inhibitors may represent a novel class of anxiolytics that specifically target stress-induced anxiety.
Copyright © 2015 the authors 0270-6474/15/353879-14$15.00/0.
The occurrence of chronic stress, depression and anxiety can increase nociception in humans and may facilitate the transition from localized to chronic widespread pain. The mechanisms underlying chronic widespread pain are still unknown, hindering the development of effective pharmacological therapies. Here, we exposed CB57BL/6 J mice to chronic unpredictable stress (CUS) to investigate how persistent stress affects nociception. Next, mice were treated with multiple intramuscular nerve growth factor (NGF) injections, which induced chronic widespread nociception. Thus, combination of CUS and NGF served as a model where psychophysiological impairment coexists with long-lasting hyperalgesia. We found that CUS increased anxiety- and depression-like behavior and enhanced basal nociception in mice. When co-applied with repeated NGF injections, CUS elicited a sustained long-lasting widespread hyperalgesia. In order to evaluate a potential therapeutic strategy for the treatment of chronic pain associated with stress, we hypothesized that the endocannabinoid system (ECS) may represent a target signaling system. We found that URB597, an inhibitor of the anandamide degrading enzyme fatty acid amide hydrolase (FAAH), and JZL184, an inhibitor of the 2-arachidonoyl glycerol (2-AG) degrading enzyme monoacylglycerol lipase (MAGL), increased eCB levels in the brain and periphery and were both effective in reducing CUS-induced anxiety measured by the light dark test and CUS-induced thermal hyperalgesia. Remarkably, the long-lasting widespread hyperalgesia induced by combining CUS and NGF was effectively reduced by URB597, but not by JZL184. Simultaneous inhibition of FAAH and MAGL did not improve the overall therapeutic response. Therefore, our findings indicate that enhancement of anandamide signaling with URB597, is a promising pharmacological approach for the alleviation of chronic widespread nociception in stress-exposed mice, and thus, it could represent a potential treatment strategy for chronic pain associated with neuropsychiatric disorders in humans.Neuropsychopharmacology accepted article preview online, 06 August 2014; doi:10.1038/npp.2014.198.
Rationale
Posttraumatic stress disorder (PTSD) and alcoholism are frequently comorbid, suggesting the possibility of overlapping neural substrates. The neurokinin 1 (NK1) receptor for substance P (SP) has been implicated in both stress- and alcohol-related behaviors. The NK1 antagonist aprepitant, clinically available as a treatment for chemotherapy-induced nausea, offers a tool to probe a potential role of the SP/NK1 system in comorbid PTSD and alcoholism.
Objectives
The aim of this study is to evaluate the efficacy of aprepitant for treatment of comorbid PTSD and alcoholism.
Methods
Fifty-three patients with PTSD and alcoholism were admitted for 4 weeks to an inpatient unit at the NIH Clinical Center and randomized to double-blind aprepitant (125 mg/day; based on PET studies reporting >90 % central receptor occupancy at this dose) or placebo. After reaching steady state, subjects were assessed for PTSD symptom severity, behavioral and neuroendocrine responses to stress and alcohol cues, and functional magnetic resonance imaging (fMRI) responses to stimuli with positive or negative emotional valence.
Results
Aprepitant treatment had no effect on PTSD symptoms or subjective or physiological responses to stress or alcohol cues. However, aprepitant robustly potentiated ventromedial prefrontal cortex (mPFC) fMRI responses to aversive visual stimuli.
Conclusions
Despite the lack of effect on PTSD symptoms and responses to stress/alcohol cues, NK1 antagonism activated the ventral mPFC, an area considered hypoactive in PTSD, during exposure to aversive stimuli. Because this brain area is critically important for extinction of fear memories and in alcohol craving and relapse, our finding suggests that NK1 antagonism might be a useful pharmacological treatment to enhance extinction-based cue-exposure therapies.
Stress is a major risk factor for the development of mood and anxiety disorders; elucidation of novel approaches to mitigate the deleterious effects of stress could have broad clinical applications. Pharmacological augmentation of central endogenous cannabinoid (eCB) signaling may be an effective therapeutic strategy to mitigate the adverse behavioral and physiological consequences of stress. Here we show that acute foot-shock stress induces a transient anxiety state measured 24 h later using the light-dark box assay and novelty-induced hypophagia test. Acute pharmacological inhibition of the anandamide-degrading enzyme, fatty acid amide hydrolase (FAAH), reverses the stress-induced anxiety state in a cannabinoid receptor-dependent manner. FAAH inhibition does not significantly affect anxiety-like behaviors in non-stressed mice. Moreover, whole brain anandamide levels are reduced 24 h after acute foot-shock stress and are negatively correlated with anxiety-like behavioral measures in the light-dark box test. These data indicate that central anandamide levels predict acute stress-induced anxiety, and that reversal of stress-induced anandamide deficiency is a key mechanism subserving the therapeutic effects of FAAH inhibition. These studies provide further support that eCB-augmentation is a viable pharmacological strategy for the treatment of stress-related neuropsychiatric disorders.
Endocannabinoids and their attending cannabinoid type 1 (CB1) receptor have been implicated in animal models of post-traumatic stress disorder (PTSD). However, their specific role has not been studied in people with PTSD. Herein, we present an in vivo imaging study using positron emission tomography (PET) and the CB1-selective radioligand [(11)C]OMAR in individuals with PTSD, and healthy controls with lifetime histories of trauma (trauma-exposed controls (TC)) and those without such histories (healthy controls (HC)). Untreated individuals with PTSD (N=25) with non-combat trauma histories, and TC (N=12) and HC (N=23) participated in a magnetic resonance imaging scan and a resting PET scan with the CB1 receptor antagonist radiotracer [(11)C]OMAR, which measures the volume of distribution (VT) linearly related to CB1 receptor availability. Peripheral levels of anandamide, 2-arachidonoylglycerol, oleoylethanolamide, palmitoylethanolamide and cortisol were also assessed. In the PTSD group, relative to the HC and TC groups, we found elevated brain-wide [(11)C]OMAR VT values (F(2,53)=7.96, P=0.001; 19.5% and 14.5% higher, respectively), which were most pronounced in women (F(1,53)=5.52, P=0.023). Anandamide concentrations were reduced in the PTSD relative to the TC (53.1% lower) and HC (58.2% lower) groups. Cortisol levels were lower in the PTSD and TC groups relative to the HC group. Three biomarkers examined collectively-OMAR VT, anandamide and cortisol-correctly classified nearly 85% of PTSD cases. These results suggest that abnormal CB1 receptor-mediated anandamide signaling is implicated in the etiology of PTSD, and provide a promising neurobiological model to develop novel, evidence-based pharmacotherapies for this disorder.Molecular Psychiatry advance online publication, 14 May 2013; doi:10.1038/mp.2013.61.
The endocannabinoid system was revealed following the understanding of the mechanism of action of marijuana's major psychotropic principle, Δ(9)-tetrahydrocannabinol, and includes two G-protein-coupled receptors (GPCRs; the cannabinoid CB1 and CB2 receptors), their endogenous ligands (the endocannabinoids, the best studied of which are anandamide and 2-arachidonoylglycerol (2-AG)), and the proteins that regulate the levels and activity of these receptors and ligands. However, other minor lipid metabolites different from, but chemically similar to, anandamide and 2-AG have also been suggested to act as endocannabinoids. Thus, unlike most other GPCRs, cannabinoid receptors appear to have more than one endogenous agonist, and it has been often wondered what could be the physiological meaning of this peculiarity. In 1999, it was proposed that anandamide might also activate other targets, and in particular the transient receptor potential of vanilloid type-1 (TRPV1) channels. Over the last decade, this interaction has been shown to occur both in peripheral tissues and brain, during both physiological and pathological conditions. TRPV1 channels can be activated also by another less abundant endocannabinoid, N-arachidonoyldopamine, but not by 2-AG, and have been proposed by some authors to act as ionotropic endocannabinoid receptors. This article will discuss the latest discoveries on this subject, and discuss, among others, how anandamide and 2-AG differential actions at TRPV1 and cannabinoid receptors contribute to making this signalling system a versatile tool available to organisms to fine-tune homeostasis.
Alcoholism is frequently co-morbid with post-traumatic stress disorder, but it is unclear how alcohol affects the neural circuits mediating recovery from trauma. We found that chronic intermittent ethanol (CIE) impaired fear extinction and remodeled the dendritic arbor of medial prefrontal cortical (mPFC) neurons in mice. CIE impaired extinction encoding by infralimbic mPFC neurons in vivo and functionally downregulated burst-mediating NMDA GluN1 receptors. These findings suggest that alcohol may increase risk for trauma-related anxiety disorders by disrupting mPFC-mediated extinction of fear.
Rationale:
The endocannabinoid (eCB) system is implicated in several psychiatric disorders. Investigating emotional-motivational dysfunctions as underlying mechanisms, a study in humans revealed that in the C385A polymorphism of the fatty acid amide hydrolase (FAAH), the degrading enzyme of the eCB anandamide (AEA), A carriers, who are characterized by increased signaling of AEA as compared to C/C carriers, exhibited reduced brain reactivity towards unpleasant faces and enhanced reactivity towards reward. However, the association of eCB system with emotional-motivational reactivity is complex and bidirectional due to upcoming compensatory processes.
Objectives:
Therefore, we further investigated the relationship of the FAAH polymorphism and emotional-motivational reactivity in humans.
Methods:
We assessed the affect-modulated startle, and ratings of valence and arousal in response to higher arousing pleasant, neutral, and unpleasant pictures in 67 FAAH C385A C/C carriers and 45 A carriers.
Results:
Contrarily to the previous functional MRI study, A carriers compared to C/C carriers exhibited an increased startle potentiation and therefore emotional responsiveness towards unpleasant picture stimuli and reduced startle inhibition indicating reduced emotional reactivity in response to pleasant pictures, while both groups did not differ in ratings of arousal and valence.
Conclusions:
Our findings emphasize the bidirectionality and thorough examination of the eCB system's impact on emotional reactivity as a central endophenotype underlying various psychiatric disorders.
Brain cannabinoid CB(1) receptors contribute to alcohol-related behaviors in experimental animals, but their potential role in humans with alcohol dependence is poorly understood. We measured CB(1) receptors in alcohol dependent patients in early and protracted abstinence, and in comparison with control subjects without alcohol use disorders, using positron emission tomography and [(18)F]FMPEP-d(2), a radioligand for CB(1) receptors. We scanned 18 male in-patients with alcohol dependence twice, within 3-7 days of admission from ongoing drinking, and after 2-4 weeks of supervised abstinence. Imaging data were compared with those from 19 age-matched healthy male control subjects. Data were also analyzed for potential influence of a common functional variation (rs2023239) in the CB(1) receptor gene (CNR1) that may moderate CB(1) receptor density. On the first scan, CB(1) receptor binding was 20-30% lower in patients with alcohol dependence than in control subjects in all brain regions and was negatively correlated with years of alcohol abuse. After 2-4 weeks of abstinence, CB(1) receptor binding remained similarly reduced in these patients. Irrespective of the diagnostic status, C allele carriers at rs2023239 had higher CB(1) receptor binding compared with non-carriers. Alcohol dependence is associated with a widespread reduction of cannabinoid CB(1) receptor binding in the human brain and this reduction persists at least 2-4 weeks into abstinence. The correlation of reduced binding with years of alcohol abuse suggests an involvement of CB(1) receptors in alcohol dependence in humans.Molecular Psychiatry advance online publication, 10 July 2012; doi:10.1038/mp.2012.100.
Hyperactivation of the amygdala following chronic stress is believed to be one of the primary mechanisms underlying the increased propensity for anxiety-like behaviors and pathological states; however, the mechanisms by which chronic stress modulates amygdalar function are not well characterized. The aim of the current study was to determine the extent to which the endocannabinoid (eCB) system, which is known to regulate emotional behavior and neuroplasticity, contributes to changes in amygdalar structure and function following chronic stress. To examine the hypothesis, we have exposed C57/Bl6 mice to chronic restraint stress, which results in an increase in fatty acid amide hydrolase (FAAH) activity and a reduction in the concentration of the eCB N-arachidonylethanolamine (AEA) within the amygdala. Chronic restraint stress also increased dendritic arborization, complexity and spine density of pyramidal neurons in the basolateral nucleus of the amygdala (BLA) and increased anxiety-like behavior in wild-type mice. All of the stress-induced changes in amygdalar structure and function were absent in mice deficient in FAAH. Further, the anti-anxiety effect of FAAH deletion was recapitulated in rats treated orally with a novel pharmacological inhibitor of FAAH, JNJ5003 (50 mg per kg per day), during exposure to chronic stress. These studies suggest that FAAH is required for chronic stress to induce hyperactivity and structural remodeling of the amygdala. Collectively, these studies indicate that FAAH-mediated decreases in AEA occur following chronic stress and that this loss of AEA signaling is functionally relevant to the effects of chronic stress. These data support the hypothesis that inhibition of FAAH has therapeutic potential in the treatment of anxiety disorders, possibly by maintaining normal amygdalar function in the face of chronic stress.Molecular Psychiatry advance online publication, 10 July 2012; doi:10.1038/mp.2012.90.
Stress plays an important role in psychiatric disorders, and preclinical evidence indicates that the central endocannabinoid system modulates endocrine and neuronal responses to stress. This study aimed to investigate the effect of acute stress on circulating concentrations of endocannabinoids (eCBs) in healthy humans. A total of 71 adults participated in two sessions in which they were exposed to either a standardized psychosocial stress procedure (Trier Social Stress Test) or a control task. Blood samples for eCB and cortisol assays and cardiovascular and subjective measures were obtained before and at regular intervals after the tasks. Serum concentrations of the eCBs, N-arachidonylethanolamine (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), as well as of the N-acylethanolamides (NAEs), N-palmitoylethanolamine (PEA) and N-oleoylethanolamine (OEA), and of the O-acylglycerol, 2-oleoylglycerol (2-OG), were determined. Compared with the control condition, stress increased serum concentrations of AEA and the other NAEs immediately after the stress period. Increases in PEA were positively correlated with increases in serum cortisol after stress. Furthermore, anxiety ratings at baseline were negatively correlated with baseline concentrations of AEA. The sex and menstrual cycle status of the subject affected the NAE responses to stress. Interestingly, subjects of Asian and African-American races exhibited different patterns of stress responses compared with the Caucasian subjects. These results indicate that stress increases circulating NAEs in healthy human volunteers. This finding supports a protective role for eCBs in anxiety. Further research is needed to elucidate the function of these lipid mediators, and to determine the mechanisms that regulate their appearance in the circulation.
Endocannabinoids are released 'on-demand' on the basis of physiological need, and can be pharmacologically augmented by inhibiting their catabolic degradation. The endocannabinoid anandamide is degraded by the catabolic enzyme fatty acid amide hydrolase (FAAH). Anandamide is implicated in the mediation of fear behaviors, including fear extinction, suggesting that selectively elevating brain anandamide could modulate plastic changes in fear. Here we first tested this hypothesis with preclinical experiments employing a novel, potent and selective FAAH inhibitor, AM3506 (5-(4-hydroxyphenyl)pentanesulfonyl fluoride). Systemic AM3506 administration before extinction decreased fear during a retrieval test in a mouse model of impaired extinction. AM3506 had no effects on fear in the absence of extinction training, or on various non-fear-related measures. Anandamide levels in the basolateral amygdala were increased by extinction training and augmented by systemic AM3506, whereas application of AM3506 to amygdala slices promoted long-term depression of inhibitory transmission, a form of synaptic plasticity linked to extinction. Further supporting the amygdala as effect-locus, the fear-reducing effects of systemic AM3506 were blocked by intra-amygdala infusion of a CB1 receptor antagonist and were fully recapitulated by intra-amygdala infusion of AM3506. On the basis of these preclinical findings, we hypothesized that variation in the human FAAH gene would predict individual differences in amygdala threat-processing and stress-coping traits. Consistent with this, carriers of a low-expressing FAAH variant (385A allele; rs324420) exhibited quicker habituation of amygdala reactivity to threat, and had lower scores on the personality trait of stress-reactivity. Our findings show that augmenting amygdala anandamide enables extinction-driven reductions in fear in mouse and may promote stress-coping in humans.
The hypothalamic-pituitary-adrenal (HPA) axis regulates the outflow of glucocorticoid hormones under basal conditions and in response to stress. Within the last decade, a large body of evidence has mounted indicating that the endocannabinoid system is involved in the central regulation of the stress response; however, the specific role endocannabinoid signaling plays in phases of HPA axis regulation, and the neural sites of action mediating this regulation, were not mapped out until recently. This review aims to collapse the current state of knowledge regarding the role of the endocannabinoid system in the regulation of the HPA axis to put together a working model of how and where endocannabinoids act within the brain to regulate outflow of the HPA axis. Specifically, we discuss the role of the endocannabinoid system in the regulation of the HPA axis under basal conditions, activation in response to acute stress, and glucocorticoid-mediated negative feedback. Interestingly, there appears to be some anatomical specificity to the role of the endocannabinoid system in each phase of HPA axis regulation, as well as distinct roles of both anandamide and 2-arachidonoylglycerol in these phases. Overall, the current level of information indicates that endocannabinoid signaling acts to suppress HPA axis activity through concerted actions within the prefrontal cortex, amygdala, and hypothalamus.
The presence and function of cannabinoid CB(2) receptors in the brain have been the subjects of much debate. We found that systemic, intranasal or intra-accumbens local administration of JWH133, a selective CB(2) receptor agonist, dose-dependently inhibited intravenous cocaine self-administration, cocaine-enhanced locomotion, and cocaine-enhanced accumbens extracellular dopamine in wild-type and CB(1) receptor knockout (CB(1)(-/-), also known as Cnr1(-/-)) mice, but not in CB(2)(-/-) (Cnr2(-/-)) mice. This inhibition was mimicked by GW405833, another CB(2) receptor agonist with a different chemical structure, and was blocked by AM630, a selective CB(2) receptor antagonist. Intra-accumbens administration of JWH133 alone dose-dependently decreased, whereas intra-accumbens administration of AM630 elevated, extracellular dopamine and locomotion in wild-type and CB(1)(-/-) mice, but not in CB(2)(-/-) mice. Intra-accumbens administration of AM630 also blocked the reduction in cocaine self-administration and extracellular dopamine produced by systemic administration of JWH133. These findings suggest that brain CB(2) receptors modulate cocaine's rewarding and locomotor-stimulating effects, likely by a dopamine-dependent mechanism.
Rationale and background
High relapse rates during abstinence are a pervasive problem in drug addiction treatment. Relapse is often associated with stress exposure, which can provoke a subjective state of drug craving that can also be demonstrated under controlled laboratory conditions. Stress-induced relapse and craving in humans can be modeled in mice, rats, and monkeys using a reinstatement model in which drug-taking behaviors are extinguished and then reinstated by acute exposure to certain stressors. Studies using the reinstatement model in rats have identified the role of several neurotransmitters and brain sites in stress-induced reinstatement of drug seeking, but the degree to which these preclinical findings are relevant to the human condition is largely unknown.
Objectives and highlights
Here, we address this topic by discussing recent results on the effect of alpha-2 adrenoceptors and substance P-NK1 receptor antagonists on stress-induced reinstatement in mice and rats and stress-induced craving and potentially stress-induced relapse in humans. We also discuss brain sites and circuits involved in stress-induced reinstatement of drug seeking in rats and those activated during stress-induced craving in humans.
Conclusions
There is evidence that alpha-2 adrenoceptor agonists and NK1 receptor antagonists decrease stress-induced drug seeking in rats and stress-induced craving in humans. Whether these drugs would also prevent stress-induced drug relapse in humans and whether similar or different brain mechanisms are involved in stress-induced reinstatement in non-humans and stress-induced drug craving and relapse in humans are subjects for future research.
Secretion of glucocorticoid hormones during stress produces an array of physiological changes that are adaptive and beneficial in the short term. In the face of repeated stress exposure, however, habituation of the glucocorticoid response is essential as prolonged glucocorticoid secretion can produce deleterious effects on metabolic, immune, cardiovascular, and neurobiological function. Endocannabinoid signaling responds to and regulates the activity of the hypothalamic-pituitary-adrenal (HPA) axis that governs the secretion of glucocorticoids; however, the role this system plays in adaptation of the neuroendocrine response to repeated stress is not well characterized. Herein, we demonstrate a divergent regulation of the two endocannabinoid ligands, N-arachidonylethanolamine (anandamide; AEA) and 2-arachidonoylglycerol (2-AG), following repeated stress such that AEA content is persistently decreased throughout the corticolimbic stress circuit, whereas 2-AG is exclusively elevated within the amygdala in a stress-dependent manner. Pharmacological studies demonstrate that this divergent regulation of AEA and 2-AG contribute to distinct forms of HPA axis habituation. Inhibition of AEA hydrolysis prevented the development of basal hypersecretion of corticosterone following repeated stress. In contrast, systemic or intra-amygdalar administration of a CB(1) receptor antagonist before the final stress exposure prevented the repeated stress-induced decline in corticosterone responses. The present findings demonstrate an important role for endocannabinoid signaling in the process of stress HPA habituation, and suggest that AEA and 2-AG modulate different components of the adrenocortical response to repeated stressor exposure.
The endocannabinoid anandamide (AEA) plays a crucial role in emotional control, and inhibition of its degradation by the fatty acid amide hydrolase (FAAH) has a potent antianxiety effect. The mechanism by which the magnification of AEA activity reduces anxiety is still largely undetermined. By using FAAH mutant mice and both intraperitoneal and intracerebroventricular administration of the FAAH inhibitor (3'-(aminocarbonyl)[1,1'-biphenyl]-3-yl)-cyclohexylcarbamate (URB597), we found that enhanced AEA signaling reversed, via central cannabinoid CB1 receptors (CB1Rs), the anxious phenotype of mice exposed to social defeat stress. This behavioral effect was associated with preserved activity of CB1Rs regulating GABA transmission in the striatum, whereas these receptors were dramatically down-regulated by stress in control animals. The hypothalamic-pituitary-adrenal (HPA) axis was not involved in the antistress effects of FAAH inhibition, although the HPA axis is a biological target of endogenous AEA. We also provided some physiological indications that striatal CB1Rs regulating GABA synapses are not the receptor targets of FAAH inhibition, which rather resulted in the stimulation of striatal CB1Rs regulating glutamate transmission. Collectively, our findings suggest that preservation of cannabinoid CB1 receptor function within the striatum is a possible synaptic correlate of the antianxiety effects of FAAH inhibition.
Background:
Obesity is a worldwide epidemic, and severe obesity is a risk factor for many diseases, including diabetes, heart disease, stroke, and some cancers. Endocannabinoid system (ECS) signaling in the brain and peripheral tissues is activated in obesity and plays a role in the regulation of body weight. The main research question here was whether quantitative measurement of plasma endocannabinoids, anandamide, and related N-acylethanolamines (NAEs), combined with genotyping for mutations in fatty acid amide hydrolase (FAAH) would identify circulating biomarkers of ECS activation in severe obesity.
Methodology/principal findings:
Plasma samples were obtained from 96 severely obese subjects with body mass index (BMI) of > or = 40 kg/m(2), and 48 normal weight subjects with BMI of < or = 26 kg/m(2). Triple-quadrupole mass spectroscopy methods were used to measure plasma ECS analogs. Subjects were genotyped for human FAAH gene mutations. The principal analysis focused on the FAAH 385 C-->A (P129T) mutation by comparing plasma ECS metabolite levels in the FAAH 385 minor A allele carriers versus wild-type C/C carriers in both groups. The main finding was significantly elevated mean plasma levels of anandamide (15.1+/-1.4 pmol/ml) and related NAEs in study subjects that carried the FAAH 385 A mutant alleles versus normal subjects (13.3+/-1.0 pmol/ml) with wild-type FAAH genotype (p = 0.04), and significance was maintained after controlling for BMI.
Conclusions/significance:
Significantly increased levels of the endocannabinoid anandamide and related NAEs were found in carriers of the FAAH 385 A mutant alleles compared with wild-type FAAH controls. This evidence supports endocannabinoid system activation due to the effect of FAAH 385 mutant A genotype on plasma AEA and related NAE analogs. This is the first study to document that FAAH 385 A mutant alleles have a direct effect on elevated plasma levels of anandamide and related NAEs in humans. These biomarkers may indicate risk for severe obesity and may suggest novel ECS obesity treatment strategies.
Psychosocial stress is a risk factor for development and exacerbation of neuropsychiatric illness. Repeated stress causes biochemical adaptations in endocannabinoid (eCB) signaling that contribute to stress-response habituation, however, the synaptic correlates of these adaptations have not been examined. Here, we show that the synthetic enzyme for the eCB 2-arachidonoylglycerol (2-AG), diacylglycerol (DAG) lipase alpha, is heterogeneously expressed in the amygdala, and that levels of 2-AG and precursor DAGs are increased in the basolateral amygdala (BLA) after 10 days, but not 1 day, of restraint stress. In contrast, arachidonic acid was decreased after both 1 and 10 days of restraint stress. To examine the synaptic correlates of these alterations in 2-AG metabolism, we used whole-cell electrophysiology to determine the effects of restraint stress on depolarization-induced suppression of inhibition (DSI) in the BLA. A single restraint stress exposure did not alter DSI compared with control mice. However, after 10 days of restraint stress, DSI duration, but not magnitude, was significantly prolonged. Inhibition of 2-AG degradation with MAFP also prolonged DSI duration; the effects of repeated restraint stress and MAFP were mutually occlusive. These data indicate that exposure to repeated, but not acute, stress produces neuroadaptations that confer BLA neurons with an enhanced capacity to elevate 2-AG content and engage in 2-AG-mediated short-term retrograde synaptic signaling. We suggest stress-induced enhancement of eCB-mediated suppression of inhibitory transmission in the BLA could contribute to affective dysregulation associated with chronic stress.
Marijuana and many of its constituent cannabinoids influence the central nervous system (CNS) in a complex and dose-dependent manner. Although CNS depression and analgesia are well documented effects of the cannabinoids, the mechanisms responsible for these and other cannabinoid-induced effects are not so far known. The hydrophobic nature of these substances has suggested that cannabinoids resemble anaesthetic agents in their action, that is, they nonspecifically disrupt cellular membranes. Recent evidence, however, has supported a mechanism involving a G protein-coupled receptor found in brain and neural cell lines, and which inhibits adenylate cyclase activity in a dose-dependent, stereoselective and pertussis toxin-sensitive manner. Also, the receptor is more responsive to psychoactive cannabinoids than to non-psychoactive cannabinoids. Here we report the cloning and expression of a complementary DNA that encodes a G protein-coupled receptor with all of these properties. Its messenger RNA is found in cell lines and regions of the brain that have cannabinoid receptors. These findings suggest that this protein is involved in cannabinoid-induced CNS effects (including alterations in mood and cognition) experienced by users of marijuana.
Data were obtained on the general population epidemiology of DSM-III-R posttraumatic stress disorder (PTSD), including information on estimated life-time prevalence, the kinds of traumas most often associated with PTSD, sociodemographic correlates, the comorbidity of PTSD with other lifetime psychiatric disorders, and the duration of an index episode.
Modified versions of the DSM-III-R PTSD module from the Diagnostic Interview Schedule and of the Composite International Diagnostic Interview were administered to a representative national sample of 5877 persons aged 15 to 54 years in the part II subsample of the National Comorbidity Survey.
The estimated lifetime prevalence of PTSD is 7.8%. Prevalence is elevated among women and the previously married. The traumas most commonly associated with PTSD are combat exposure and witnessing among men and rape and sexual molestation among women. Posttraumatic stress disorder is strongly comorbid with other lifetime DSM-III-R disorders. Survival analysis shows that more than one third of people with an index episode of PTSD fail to recover even after many years.
Posttraumatic stress disorder is more prevalent than previously believed, and is often persistent. Progress in estimating age-at-onset distributions, cohort effects, and the conditional probabilities of PTSD from different types of trauma will require future epidemiologic studies to assess PTSD for all lifetime traumas rather than for only a small number of retrospectively reported "most serious" traumas.
Cannabinoids are the most popular illicit drugs used for recreational purposes worldwide. However, the neurobiological substrate of their mood-altering capacity has not been elucidated so far. Here we report that CB1 cannabinoid receptors are expressed at high levels in certain amygdala nuclei, especially in the lateral and basal nuclei, but are absent in other nuclei (e.g., in the central nucleus and in the medial nucleus). Expression of the CB1 protein was restricted to a distinct subpopulation of GABAergic interneurons corresponding to large cholecystokinin-positive cells. Detailed electron microscopic investigation revealed that CB1 receptors are located presynaptically on cholecystokinin-positive axon terminals, which establish symmetrical GABAergic synapses with their postsynaptic targets. The physiological consequence of this particular anatomical localization was investigated by whole-cell patch-clamp recordings in principal cells of the lateral and basal nuclei. CB1 receptor agonists WIN 55,212-2 and CP 55,940 reduced the amplitude of GABA(A) receptor-mediated evoked and spontaneous IPSCs, whereas the action potential-independent miniature IPSCs were not significantly affected. In contrast, CB1 receptor agonists were ineffective in changing the amplitude of IPSCs in the rat central nucleus and in the basal nucleus of CB1 knock-out mice. These results suggest that cannabinoids target specific elements in neuronal networks of given amygdala nuclei, where they presynaptically modulate GABAergic synaptic transmission. We propose that these anatomical and physiological features, characteristic of CB1 receptors in several forebrain regions, represent the neuronal substrate for endocannabinoids involved in retrograde synaptic signaling and may explain some of the emotionally relevant behavioral effects of cannabinoid exposure.
Stress affects a constellation of physiological systems in the body and evokes a rapid shift in many neurobehavioral processes. A growing body of work indicates that the endocannabinoid (eCB) system is an integral regulator of the stress response. In the current review, we discuss the evidence to date that demonstrates stress-induced regulation of eCB signaling and the consequential role changes in eCB signaling have with respect to many of the effects of stress. Across a wide array of stress paradigms, studies have generally shown that stress evokes bidirectional changes in the two eCB molecules, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG), with stress exposure reducing AEA levels and increasing 2-AG levels. Additionally, in almost every brain region examined, exposure to chronic stress reliably causes a downregulation or loss of cannabinoid type 1 (CB1) receptors. With respect to the functional role of changes in eCB signaling during stress, studies have demonstrated that the decline in AEA appears to contribute to the manifestation of the stress response, including activation of the hypothalamic–pituitary–adrenal (HPA) axis and increases in anxiety behavior, while the increased 2-AG signaling contributes to termination and adaptation of the HPA axis, as well as potentially contributing to changes in pain perception, memory and synaptic plasticity. More so, translational studies have shown that eCB signaling in humans regulates many of the same domains and appears to be a critical component of stress regulation, and impairments in this system may be involved in the vulnerability to stress-related psychiatric conditions, such as depression and posttraumatic stress disorder. Collectively, these data create a compelling argument that eCB signaling is an important regulatory system in the brain that largely functions to buffer against many of the effects of stress and that dynamic changes in this system contribute to different aspects of the stress response.
Background:
Data were obtained on the general population epidemiology of DSM-III-R posttraumatic stress disorder (PTSD), including information on estimated lifetime prevalence, the kinds of traumas most often associated with PTSD, sociodemographic correlates, the comorbidity of PTSD with other lifetime psychiatric disorders, and the duration of an index episode.Methods:
Modified versions of the DSM-III-R PTSD module from the Diagnostic Interview Schedule and of the Composite International Diagnostic Interview were administered to a representative national sample of 5877 persons aged 15 to 54 years in the part II subsample of the National Comorbidity Survey.Results:
The estimated lifetime prevalence of PTSD is 7.8%. Prevalence is elevated among women and the previously married. The traumas most commonly associated with PTSD are combat exposure and witnessing among men and rape and sexual molestation among women. Posttraumatic stress disorder is strongly comorbid with other lifetime DSM-III-R disorders. Survival analysis shows that more than one third of people with an index episode of PTSD fail to recover even after many years.Conclusions:
Posttraumatic stress disorder is more prevalent than previously believed, and is often persistent. Progress in estimating age-at-onset distributions, cohort effects, and the conditional probabilities of PTSD from different types of trauma will require future epidemiologic studies to assess PTSD for all lifetime traumas rather than for only a small number of retrospectively reported "most serious" traumas.
Alcohol addiction is a chronic relapsing disorder that presents a substantial public health problem, and is frequently co-morbid with posttraumatic stress disorder (PTSD). Craving for alcohol is a predictor of relapse to alcohol use, and is triggered by cues associated with alcohol and trauma. Identification of reliable and valid laboratory methods for craving induction is an important objective for alcoholism and PTSD research. The present study compares two methods for induction of craving via stress and alcohol cues in individuals with co-morbid alcohol dependence (AD) and PTSD: the combined Trier social stress test and cue reactivity paradigm (Trier/CR), and a guided imagery (Scripts) paradigm. Outcomes include self-reported measures of craving, stress and anxiety as well as endocrine measures. Subjects were 52 individuals diagnosed with co-morbid AD and PTSD seeking treatment at the National Institute on Alcohol Abuse and Alcoholism inpatient research facility. They participated in a 4-week inpatient study of the efficacy of a neurokinin 1 antagonist to treat co-morbid AD and PTSD, and which included the two challenge procedures. Both the Trier/CR and Scripts induced craving for alcohol, as well as elevated levels of subjective distress and anxiety. The Trier/CR yielded significant increases in adrenocorticotropic hormone and cortisol, while the Scripts did not. Both paradigms are effective laboratory means of inducing craving for alcohol. Further research is warranted to better understand the mechanisms behind craving induced by stress versus alcohol cues, as well as to understand the impact of co-morbid PTSD and AD on craving.
A long-standing literature linking endocannabinoids (ECBs) to stress, fear, and anxiety has led to growing interest in developing novel anxiolytics targeting the ECB system. Following rapid on-demand biosynthesis and degradation upon neuronal activation, the ECB N-arachidonoylethanolamide (anandamide, AEA) is actively degraded by the serine hydrolase enzyme, fatty acid amide hydrolase (FAAH). Exposure to stress rapidly mobilizes FAAH to deplete the signaling pool of AEA and increase neuronal excitability in a key anxiety-mediating region - the basolateral amygdala (BLA). Gene deletion or pharmacological inhibition of FAAH prevents stress-induced reductions in AEA and associated increases in BLA dendritic hypertrophy and anxiety-like behavior. Additionally, inhibition of FAAH facilitates long-term fear extinction and rescues deficient fear extinction in rodent models by enhancing AEA-CB1 (cannabinoid type 1) receptor signaling and synaptic plasticity in the BLA. These preclinical findings propose restoring deficient BLA AEA levels by pharmacologically inhibiting FAAH as a mechanism to therapeutically mitigate the effects of traumatic stress.
Hyperactivation of the amygdala following chronic stress is believed to be one of the primary mechanisms underlying the increased propensity for anxiety-like behaviors and pathological states; however, the mechanisms by which chronic stress modulates amygdalar function are not well characterized. The aim of the current study was to determine the extent to which the endocannabinoid (eCB) system, which is known to regulate emotional behavior and neuroplasticity, contributes to changes in amygdalar structure and function following chronic stress. To examine the hypothesis, we have exposed C57/Bl6 mice to chronic restraint stress, which results in an increase in fatty acid amide hydrolase (FAAH) activity and a reduction in the concentration of the eCB N-arachidonylethanolamine (AEA) within the amygdala. Chronic restraint stress also increased dendritic arborization, complexity and spine density of pyramidal neurons in the basolateral nucleus of the amygdala (BLA) and increased anxiety-like behavior in wild-type mice. All of the stress-induced changes in amygdalar structure and function were absent in mice deficient in FAAH. Further, the anti-anxiety effect of FAAH deletion was recapitulated in rats treated orally with a novel pharmacological inhibitor of FAAH, JNJ5003 (50 mg per kg per day), during exposure to chronic stress. These studies suggest that FAAH is required for chronic stress to induce hyperactivity and structural remodeling of the amygdala. Collectively, these studies indicate that FAAH-mediated decreases in AEA occur following chronic stress and that this loss of AEA signaling is functionally relevant to the effects of chronic stress. These data support the hypothesis that inhibition of FAAH has therapeutic potential in the treatment of anxiety disorders, possibly by maintaining normal amygdalar function in the face of chronic stress.
more than two decades ago, the timeline was developed as a procedure to aid recall of past drinking / that method, first referred to as the gathering of daily drinking disposition data and later labeled as the timeline follow-back (TLFB) method, is the focus of this chapter / TLFB appears to provide a relatively accurate portrayal of drinking and has both clinical and research utility
administration of the TLFB technique / psychometric properties / test–retest reliability / subject-collateral comparisons / concurrent validity (PsycINFO Database Record (c) 2012 APA, all rights reserved)
This study examines the psychometric properties of two versions of the PTSD Sympton Scale (PSS). The scale contains 17 items that diagnose PTSD according to DSM-III-R criteria and assess the severity of PTSD symptoms. An interview and self-report version of the PSS were administered to a sample of 118 recent rape and non-sexual assault victims. The results indicate that both versions of the PSS have satisfactory internal consistency, high test-retest reliability, and good concurrent validity. The interview version yielded high interrater agreement when administred separately by two interviewers and excellent convergent validity with the SCID. When used to diagnose PTSD, the self-report version of the PSS was somewhat more conservative than the interview version.
Alcoholism is a chronic, relapsing illness in which stress and alcohol cues contribute significantly to relapse risk. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, increased anxiety, and high alcohol craving have been documented during early alcohol recovery, but their influence on relapse risk has not been well studied.
To investigate these responses in treatment-engaged, 1-month-abstinent, recovering alcohol-dependent patients relative to matched controls (study 1) and to assess whether HPA axis function, anxiety, and craving responses are predictive of subsequent alcohol relapse and treatment outcome (study 2).
Experimental exposure to stress, alcohol cues, and neutral, relaxing context to provoke alcohol craving, anxiety, and HPA axis responses (corticotropin and cortisol levels and cortisol to corticotropin ratio) and a prospective 90-day follow-up outcome design to assess alcohol relapse and aftercare treatment outcomes.
Inpatient treatment in a community mental health center and hospital-based research unit.
Treatment-engaged alcohol-dependent individuals and healthy controls.
Time to alcohol relapse and to heavy drinking relapse.
Significant HPA axis dysregulation, marked by higher basal corticotropin level and lack of stress- and cue-induced corticotropin and cortisol responses, higher anxiety, and greater stress- and cue-induced alcohol craving, was seen in the alcohol-dependent patients vs the control group. Stress- and cue-induced anxiety and stress-induced alcohol craving were associated with fewer days in aftercare alcohol treatment. High provoked alcohol craving to both stress and to cues and greater neutral, relaxed-state cortisol to corticotropin ratio (adrenal sensitivity) were each predictive of shorter time to alcohol relapse.
These results identify a significant effect of high adrenal sensitivity, anxiety, and increased stress- and cue-induced alcohol craving on subsequent alcohol relapse and treatment outcomes. Findings suggest that new treatments that decrease adrenal sensitivity, stress- and cue-induced alcohol craving, and anxiety could be beneficial in improving alcohol relapse outcomes.
The term cannabinoids encompasses compounds produced by the plant Cannabis sativa, such as Δ
9-tetrahydrocannabinol, and synthetic counterparts. Their actions occur mainly through activation of cannabinoid type 1 (CB1) receptors. Arachidonoyl ethanolamide (anandamide) and 2-arachidonoyl glycerol (2-AG) serve as major endogenous ligands (endocannabinoids) of CB1 receptors. Hence, the cannabinoid receptors, the endocannabinoids, and their metabolizing enzymes comprise the endocannabinoid system. Cannabinoids induce diverse responses on anxiety- and fear-related behaviors. Generally, low doses tend to induce anxiolytic-like effects, whereas high doses often cause the opposite. Inhibition of endocannabinoid degradation seems to circumvent these biphasic effects by enhancing CB1 receptor signaling in a temporarily and spatially restricted manner, thus reducing anxiety-like behaviors. Pharmacological blockade or genetic deletion of CB1 receptors, in turn, primarily exerts anxiogenic-like effects and impairments in extinction of aversive memories. Interestingly, pharmacological blockade of Transient Receptor Potential Vanilloid Type-1 (TRPV1) channel, which can be activated by anandamide as well, has diametrically opposite consequences. This book chapter summarizes and conceptualizes our current knowledge about the role of (endo)cannabinoids in fear and anxiety and outlines implications for an exploitation of the endocannabinoid system as a target for new anxiolytic drugs.
The present review summarizes the latest information on the role and the pharmacological modulation of the endocannabinoid system in mood disorders and its potential implication in psychotic disorders such as schizophrenia. Reduced functionality might be considered a predisposing factor for major depression, so boosting endocannabinoid tone might be a useful alternative therapeutic approach for depressive disorders. The picture regarding endocannabinoids and anxiety is more complicated since either too much or too little anandamide can lead to anxiety states. However, a small rise in its level in specific brain areas might be beneficial for the response to a stressful situation and therefore to tone down anxiety. This effect might be achieved with low doses of cannabinoid indirect agonists, such as blockers of the degradative pathway (i.e. FAAH) or re-uptake inhibitors. Moreover several lines of experimental and clinical evidence point to a dysregulation of the endocannabinoid system in schizophrenia. The high anandamide levels found in schizophrenic patients, negatively correlated with psychotic symptoms, point to a protective role, whereas the role of 2-arachidonoyl glycerol is still unclear. There is a potential for pharmacological manipulation of the endocannabinoid system as a novel approach for treating schizophrenia, although experimental findings are still controversial, often with different effects depending on the drug, the dose, the species and the model used for simulating positive or negative symptoms. Besides all these limitations, SR141716A and cannabidiol show the most constant antipsychotic properties in dopamine- and glutamate-based models of schizophrenia, with profiles similar to an atypical antipsychotic drug.
Recent studies in rodents have suggested a role for the central endocannabinoid system in the regulation of mood and alcohol related behaviors. Alcohol use disorder is often associated with suicidal behavior. In the present study, we examined whether abnormalities in the endocannabinoid system in the ventral striatum are associated with alcohol dependence and suicide. The levels of CB1 receptors, receptor-mediated G-protein signaling, and activity and level of the fatty acid amide hydrolase (FAAH) were analyzed postmortem in the ventral striatum of alcohol-dependent nonsuicides (CA, n=9), alcohol-dependent suicides (AS, n=9) and nonpsychiatric controls (C, n=9). All subjects underwent a psychological autopsy, and toxicological and neuropathological examinations. The levels of the CB1 receptors and the CB1 receptor-mediated G-protein signaling were significantly lower in the ventral striatum of CA compared to the control group. However, these parameters were elevated in AS when compared to CA group. The activity of FAAH enzyme was lower in CA compared to the control group while it was found to be significantly higher in AS compared with CA group. These findings suggest that alcohol dependence is associated with the downregulation of the CB1 receptors, while suicide is linked to the upregulation of these receptors in the ventral striatum. Alteration in the activity of FAAH enzyme that regulates the anandamide (AEA) content might in turn explain differences in the CB1 receptor function in alcohol dependence and suicide. These findings may have etiological and therapeutic implications for the treatment of alcohol addiction and suicidal behavior.
Endocannabinoids inhibit hypothalamic-pituitary-adrenal (HPA) axis activity; however, the neural substrates and pathways subserving this effect are not well characterized. The amygdala is a forebrain structure that provides excitatory drive to the HPA axis under conditions of stress. The aim of this study was to determine the contribution of endocannabinoid signaling within distinct amygdalar nuclei to activation of the HPA axis in response to psychological stress. Exposure of rats to 30-min restraint stress increased the hydrolytic activity of fatty acid amide hydrolase (FAAH) and concurrently decreased content of the endocannabinoid/CB(1) receptor ligand N-arachidonylethanolamine (anandamide; AEA) throughout the amygdala. In stressed rats, AEA content in the amygdala was inversely correlated with serum corticosterone concentrations. Pharmacological inhibition of FAAH activity within the basolateral amygdala complex (BLA) attenuated stress-induced corticosterone secretion; this effect was blocked by co-administration of the CB(1) receptor antagonist AM251, suggesting that stress-induced decreases in CB(1) receptor activation by AEA contribute to activation of the neuroendocrine stress response. Local administration into the BLA of a CB(1) receptor agonist significantly reduced stress-induced corticosterone secretion, whereas administration of a CB(1) receptor antagonist increased corticosterone secretion. Taken together, these findings suggest that the degree to which stressful stimuli reduce amygdalar AEA/CB(1) receptor signaling contributes to the magnitude of the HPA response.
Endocannabinoids modulate eating behavior; hence, endocannabinoid genes may contribute to the biological vulnerability to eating disorders. The rs1049353 (1359 G/A) single nucleotide polymorphism (SNP) of the gene coding the endocannabinoid CB1 receptor (CNR1) and the rs324420 (cDNA 385C to A) SNP of the gene coding fatty acid amide hydrolase (FAAH), the major degrading enzyme of endocannabinoids, have been suggested to have functional effects on mature proteins. Therefore, we explored the possibility that those SNPs were associated to anorexia nervosa and/or bulimia nervosa. The distributions of the CNR1 1359 G/A SNP and of the FAAH cDNA 385C to A SNP were investigated in 134 patients with anorexia nervosa, 180 patients with bulimia nervosa and 148 normal weight healthy controls. Additive effects of the two SNPs in the genetic susceptibility to anorexia nervosa and bulimia nervosa were also tested. As compared to healthy controls, anorexic and bulimic patients showed significantly higher frequencies of the AG genotype and the A allele of the CNR1 1359 G/A SNP. Similarly, the AC genotype and the A allele of the FAAH cDNA 385C to A SNP were significantly more frequent in anorexic and bulimic individuals. A synergistic effect of the two SNPs was evident in anorexia nervosa but not in bulimia nervosa. Present findings show for the first time that the CNR1 1359 G/A SNP and the FAAH cDNA 385C to A SNP are significantly associated to anorexia nervosa and bulimia nervosa, and demonstrate a synergistic effect of the two SNPs in anorexia nervosa.
Fatty acid amide hydrolase (FAAH) is a key enzyme in regulating endocannabinoid (eCB) signaling. A common single nucleotide polymorphism (C385A) in the human FAAH gene has been associated with increased risk for addiction and obesity.
Using imaging genetics in 82 healthy adult volunteers, we examined the effects of FAAH C385A on threat- and reward-related human brain function.
Carriers of FAAH 385A, associated with reduced enzyme and possibly increased eCB signaling, had decreased threat-related amygdala reactivity but increased reward-related ventral striatal reactivity in comparison with C385 homozygotes. Similarly divergent effects of FAAH C385A genotype were manifest at the level of brain-behavior relationships. The 385A carriers showed decreased correlation between amygdala reactivity and trait anxiety but increased correlation between ventral striatal reactivity and delay discounting, an index of impulsivity.
Our results parallel pharmacologic and genetic dissection of eCB signaling, are consistent with the psychotropic effects of Delta(9)-tetrahydrocannabinol, and highlight specific neural mechanisms through which variability in eCB signaling impacts complex behavioral processes related to risk for addiction and obesity.
The actions of the active principle of marihuana, delta 9-tetrahydrocannabinol, are mimicked by synthetic cannabinoid agonists showing high potency and enantio-selectivity in behavioral assays. These drugs have been used to characterize cannabinoid receptor binding, biochemistry and pharmacology, leading to a better understanding of the effects of cannabinoids in the CNS of humans and experimental animals.
This report presents initial findings on the reliability and validity of a new retrospective measure of child abuse and neglect, the Childhood Trauma Questionnaire.
Two hundred eighty-six drug- or alcohol-dependent patients were given the Childhood Trauma Questionnaire as part of a larger test battery, and 40 of these patients were given the questionnaire again after an interval of 2 to 6 months. Sixty-eight of the patients were also given a structured interview for child abuse and neglect, the Childhood Trauma Interview, that was developed by the authors.
Principal-components analysis of responses on the Childhood Trauma Questionnaire yielded four rotated orthogonal factors: physical and emotional abuse, emotional neglect, sexual abuse, and physical neglect. Cronbach's alpha for the factors ranged from 0.79 to 0.94, indicating high internal consistency. The Childhood Trauma Questionnaire also demonstrated good test-retest reliability over a 2- to 6-month interval (intraclass correlation = 0.88), as well as convergence with the Childhood Trauma Interview, indicating that patients' reports of child abuse and neglect based on the Childhood Trauma Questionnaire were highly stable, both over time and across type of instruments.
These findings provide strong initial support for the reliability and validity of the Childhood Trauma Questionnaire.
Restricted maximum likelihood (REML) is now well established as a method for estimating the parameters of the general Gaussian linear model with a structured covariance matrix, in particular for mixed linear models. Conventionally, estimates of precision and inference for fixed effects are based on their asymptotic distribution, which is known to be inadequate for some small-sample problems. In this paper, we present a scaled Wald statistic, together with an F approximation to its sampling distribution, that is shown to perform well in a range of small sample settings. The statistic uses an adjusted estimator of the covariance matrix that has reduced small sample bias. This approach has the advantage that it reproduces both the statistics and F distributions in those settings where the latter is exact, namely for Hotelling T2 type statistics and for analysis of variance F-ratios. The performance of the modified statistics is assessed through simulation studies of four different REML analyses and the methods are illustrated using three examples.