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Cannabinoids and obsessive-compulsive disorder

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Abstract

Obsessive-compulsive disorder (OCD) is a chronic and fluctuating neuropsychiatric condition characterized by intrusive thoughts (obsessions) and repetitive ritualistic behaviors (compulsions). Recent evidence suggests that endocannabinoids (eCBs) can play a role in this disorder. Cannabinoid receptors are significantly expressed in most parts of the main circuitry related to OCD, the cortico-striatal-thalamic circuitry, being able to modulate the release of key neurotransmitters such as glutamate, dopamine, GABA, and serotonin. Preclinical studies using the marble burying test show that enhancement of CB1 function by direct agonists or inhibitors of the enzymes responsible for the metabolism of eCBs (including the phytocannabinoid cannabidiol) presents anti-compulsive behavior activity. Although additional studies are needed to elucidate the role of eCBs in OCD, these neurotransmitters could be an important future target for new therapeutic approaches to this disorder.

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... These aberrant behaviors can be related to several human neuropsychiatric conditions such as Huntington's disease and obsessive-compulsive disorder (OCD). In a simplified version, the CSTC is divided into two major pathways: direct and indirect (Casarotto, Gomes & Guimarães, 2015). The direct pathway comprises the cortical projections to globus pallidus (pars internalis) and substantia nigra pars reticulata, while the indirect pathway engages a more complex set of relay structures, involving the globus pallidus pars externalis and subthalamic nucleus (for review see Canales & Graybiel, 2000;Canales & Graybiel, 2000). ...
... The resultant activity between these two pathways regulates the output of the basal ganglia in favor of one of the two possible effects: increase in the repetitive movements (favored by the direct pathway activity) or inhibition of such programs, a consequence of activation of the indirect pathway. Although highly simplified, this model of the CSTC circuit provides a useful framework for understanding circuit physiology and putative dysfunctions (Casarotto, Gomes & Guimarães, 2015). ...
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... These aberrant behaviors can be related to several human neuropsychiatric conditions such as Huntington's disease and obsessive-compulsive disorder (OCD). In a simplified version, the CSTC is divided into two major pathways: direct and indirect 4 . The direct pathway comprises the cortical projections to globus pallidus Chevaleyre et al. 2006 7 ]. ...
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Tourette syndrome (TS) and obsessive-compulsive disorder (OCD) both are neuropsychiatric disorders associated with abnormalities in dopamine neurotransmission. Aims of this study were to quantify striatal D2/3 receptor availability in TS and OCD, and to examine dopamine release and symptom severity changes in both disorders following amphetamine challenge. Changes in [(11)C]raclopride binding potential (BPND) were assessed using positron emission tomography before and after administration of d-amphetamine (0.3mgkg(-1)) in 12 TS patients without comorbid OCD, 12 OCD patients without comorbid tics, and 12 healthy controls. Main outcome measures were baseline striatal D2/3 receptor BPND and change in BPND following amphetamine as a measure of dopamine release. Voxel-based analysis revealed significantly decreased baseline [(11)C]raclopride BPND in bilateral putamen of both patient groups vs. healthy controls, differences being more pronounced in the TS than in the OCD group. Changes in BPND following amphetamine were not significantly different between groups. Following amphetamine administration, tic severity increased in the TS group, which correlated with BPND changes in right ventral striatum. Symptom severity in the OCD group did not change significantly following amphetamine challenge and was not associated with changes in BPND. This study provides evidence for decreased striatal D2/3 receptor availability in TS and OCD, presumably reflecting higher endogenous dopamine levels in both disorders. In addition, it provides the first direct evidence that ventral striatal dopamine release is related to the pathophysiology of tics.
Article
Background: Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder associated with a significant degree of functional disability and poor quality of life. Pharmacotherapy may have a substantial impact on the course and outcome of OCD. Method: We review the evidence supporting available strategies for the pharmacological treatment of OCD. Results: Selective serotonin reuptake inhibitors (SSRIs) remain the pharmacological treatment of choice and are associated with improved health-related quality of life. Discontinuation is associated with relapse and loss of quality of life, implying treatment should continue long-term. A substantial minority of patients who fail to respond to SSRI may benefit from dose elevation or adjunctive antipsychotics, though long-term trials validating the effectiveness and tolerability of these strategies are relatively lacking. Conclusion: The pharmacological evidence-base for the treatment of OCD is becoming increasingly robust. Treatment with SSRIs and clomipramine remains uncontroversial and improvements are sustained over time. Newer compounds targeting serotonin receptor subtypes and other neurotransmitter systems are undergoing evaluation.
Article
Background: Conventional and atypical antipsychotic medications are approved by the FDA for treatment of schizophrenia and bipolar disorder. Over many decades, the widespread use of conventional antipsychotics produced various side effects requiring additional medications, such as the atypical antipsychotics. Beginning in 2006, 9 atypical antipsychotic drugs have been approved by the FDA for indications that were previously off-label uses: aripiprazole (as augmentation for major depressive disorder [MDD] and for autism spectrum disorders), asenapine, clozapine, iloperidone, olanzapine (in combination with fluoxetine for MDD and bipolar depression), paliperidone, quetiapine (quetiapine and quetiapine XR [extended release] as monotherapy in bipolar depression and quetiapine XR as augmentation for MDD), risperidone (for autism spectrum disorders), and ziprasidone. In 2006, the Agency for Healthcare Research and Quality (AHRQ) published a systematic review on the comparative effectiveness of off-label uses of atypical antipsychotics. Since that time, numerous studies have been published evaluating these therapies in various new off-label uses; new or increased adverse effects have been observed with off-label uses; new atypical antipsychotics have been approved; and previously off-label uses have been approved for some atypical antipsychotics. Hence, AHRQ published an updated review in September 2011 that summarized the benefits and harms of atypical antipsychotics in the treatment of attention-deficit hyperactivity disorder/attention deficit disorder (ADHD), anxiety, behavioral disturbances of dementia and severe geriatric agitation, depression, eating disorders, insomnia, obsessive-compulsive disorder (OCD), personality disorder, post-traumatic stress disorder (PTSD), substance use and dependence disorders, and Tourette's syndrome. The new report also investigated topics for which data in the previous report were found to be insufficient to make conclusions, including subpopulations (i.e., race/ethnicity, gender) that would benefit most from atypical antipsychotics, appropriate dose, and time needed to see clinical improvement. The 2011 review included the following atypical antipsychotics: aripiprazole, olanzapine, quetiapine, risperidone, and ziprasidone; no clinical trials were found for off-label use of the 3 most recently FDA-approved atypical antipsychotics (asenapine, iloperidone, and paliperidone). Objectives: To (a) familiarize health care professionals with the methods and findings from AHRQ's 2011 Comparative Effectiveness Review (CER) of off-label use of atypical antipsychotics, (b) encourage consideration of the clinical and managed care applications of the review findings, and (c) identify limitations and gaps in the existing research with respect to the benefits and risks of off-label use of atypical antipsychotics. Summary: Antipsychotic medications are FDA approved for the treatment of schizophrenia and bipolar disorder. Conventional antipsychotics have been widely used for decades and spurred the development of the atypical antipsychotics. Atypical antipsychotics were produced and are now being used for patients who may have experienced various side effects while using conventional antipsychotics.In 2006, an AHRQ study reviewed off-label uses of atypical antipsychotics (excluding clozapine because of its association with potentially fatal bone marrow suppression and the requirement for frequent blood tests for safety monitoring). Findings indicated that the most common off-label uses of these drugs included depression, OCD, PTSD, personality disorders, Tourette's syndrome, autism, and agitation in dementia. The reviewers concluded in 2006 that overall there was not sufficiently high strength of evidence of efficacy for any off-label use of atypical antipsychotics. There was, however, strong evidence for an increased risk of adverse events with off-label use, including significant weight gain and sedation and increased mortality among the elderly.Since the 2006 review, significant developments occurred in the use of atypical antipsychotics, including FDA approval of the atypical antipsychotics asenapine, iloperidone, and paliperidone and FDA approval of previous off-label uses: (a) quetiapine and quetiapine XR as monotherapy in bipolar depression; (b) quetiapine XR as augmentation therapy for MDD; (c) aripiprazole as augmentation therapy for MDD; (d) olanzapine/fluoxetine combination for MDD; (e) olanzapine/fluoxetine combination for bipolar depression; and (f) risperidone and aripiprazole for autism spectrum disorders. Additional studies have been published for new off-label uses, and there have been reports of new or increased adverse effects for off-label uses.Further review of previously insufficient information was warranted on subpopulations where treatment modification such as dosing may increase efficacy. The 2006 review did not have sufficient information to make conclusions regarding subpopulations (i.e., race/ethnicity, gender) that would benefit most from atypical antipsychotics, appropriate dosing, and the duration of treatment needed to see clinical improvement. The updated AHRQ report in 2011 reviewed off-label uses of atypical antipsychotic medications in anxiety, ADHD, behavioral disturbances of dementia and severe geriatric agitation, MDD, eating disorders, insomnia, OCD, PTSD, personality disorders, substance abuse, and Tourette's syndrome; autism was included in the 2006 review but is now reviewed in a separate report of the comparative effectiveness of antipsychotics for on-label uses. The significant findings in the updated review include (a) small but statistically significant benefits for olanzapine, aripiprazole, and risperidone for elderly patients with dementia; (b) quetiapine appears superior to placebo for general anxiety disorder (GAD); (c) risperidone was associated with benefits in the treatment of OCD; and (d) adverse events are common. Atypical antipsychotics were not effective in the treatment of eating disorders or personality disorder. The evidence did not support the use of atypical antipsychotics in the treatment of substance abuse, and data were inconclusive for the use of these medications for insomnia. The number needed to harm (NNH) was calculated for adverse events in elderly patients, including risk of death (NNH = 87), stroke (NNH = 53 for risperidone), extrapyramidal symptoms (NNH = 10 for olanzapine and NNH = 20 for risperidone), and urinary symptoms (NNH = 16 to 36). Adverse events in nonelderly adults included weight gain (particularly with olanzapine), fatigue, sedation, akathisia (with aripiprazole), and extrapyramidal symptoms.
Article
The most consistent finding in clinical research of obsessive compulsive disorder (OCD) is the significant treatment advantage of potent serotonin uptake inhibitors (SUIs) over other classes of antidepressant and antianxiety drugs. Clinical neurobiological studies of OCD, however, have yielded limited and inconsistent evidence for significant fundamental abnormalities in monoamine systems including serotonin, norepinephrine and dopamine. Furthermore, one-third to one-half of OCD patients do not experience a clinically meaningful improvement with SUI treatment. Investigation beyond the monoamine systems may be necessary in order to more fully understand the pathophysiology of obsessive–compulsive symptoms and develop improved treatments. Evidence from preclinical studies suggests that neuropeptides may have important influences on memory acquisition, maintenance and retrieval; grooming, maternal, sexual and aggressive behavior; fixed action patterns; and stereotyped behavior; these phenomena may relate to some features of OCD. In addition, extensive interactions have been identified in the brain between neuropeptidergic and monoaminergic systems, including co-localization among specific populations of neurons. The purpose of this review is to present the current knowledge of the role of neuropeptides in the clinical neurobiology of children, adolescents and adults with OCD focusing primarily on results from pharmacological challenge and cerebrospinal fluid studies. Where evidence exists, developmentally regulated differences in neuropeptide function between children and adolescents versus adults with OCD will be emphasized; these data are intended to underscore the potential importance of establishing the age of symptom onset (childhood versus adult) in individual patients with OCD participating in clinical neurobiological investigations. Likewise, where information is available, differences in measures of neuropeptides between patients with non-tic-related OCD versus tic-related OCD will be highlighted; these data will demonstrate the critical value of diagnostic precision, as these two particular subtypes of OCD may have different neurochemical underpinnings.
Article
Abnormality of orbitofronto-striatal circuits was postulated in obsessive-compulsive disorder (OCD). The aim of this study is to test the abnormality hypothesis of orbitofronto-striatal circuits and explore whether there are any other dysfunctional brain regions in OCD using a resting-state functional magnetic resonance imaging (fMRI), and further investigate the relationship between the whole-brain voxel-based spontaneous neuronal activity of patients with OCD and clinical characteristics. 23 patients with OCD and 23 age- and gender-matched normal controls were examined using resting-state fMRI, and amplitude of low-frequency fluctuation (ALFF) approach was used to analyze fMRI data. Compared with normal controls, patients with OCD presented increased ALFF in the bilateral orbitofrontal cortex (OFC), anterior cingulate cortex (ACC) as well as decreased ALFF in the bilateral cerebellum and parietal cortex (P<0.01, corrected). Additionally, the ALFF values in bilateral OFC were positively correlated with total Y-BOCS scores (P<0.005, uncorrected). Our findings added an expanding literature to the abnormality hypothesis of orbitofronto-striatal circuits and showed the changed spontaneous neuronal activity of the parietal cortex and cerebellum may also play an important role in the pathophysiology in patients with OCD.
Article
There is a prominent role of the cannabinoid system to control basal ganglia function, in respect to reward, psychomotor function and motor control. Cannabinoid dysregulations might have a pathogenetic role in dopamine- and basal ganglia related neuropsychiatric disorders, such as drug addiction, psychosis, Parkinson's disease and Huntington's disease. This review highlights interactions between cannabinoids, and dopamine, to modulate neurotransmitter release and synaptic plasticity in the context of drug addiction, psychosis and cognition. Modulating endocannabinoid function, as a plasticity based therapeutic strategy, in the above pathologies with particular focus on cannabinoid receptor type 1 (CB1 receptor) antagonists/inverse agonists, is discussed. On the basis of the existing literature and of new experimental evidence presented here, CB1 receptor antagonists might be beneficial in disease states associated with hedonic dysregulation, and with cognitive dysfunction in particular in the context of psychosis. It is suggested that this effects might be mediated via a hyperglutamatergic state through metabotropic glutamate activation. Indications for endocannabinoid catabolism inhibitors in psychiatric disorders, that might be CB1 receptor independent and might involve TRPV1 receptors, are also discussed.
Article
Activation of cannabinoid CB(1) receptor is shown to inhibit marble-burying behavior (MBB), a behavioral model for assessing obsessive-compulsive disorder (OCD). Anandamide, an endogenous agonist at CB(1) receptor also activates the transient receptor potential vanilloid type 1 (TRPV1) channels but at a higher concentration. Furthermore, anandamide-mediated TRPV1 effects are opposite to that of the CB(1) receptor. Therefore, the present study was carried out to investigate the influence of low and high doses of anandamide on MBB in CB(1) and TRPV1 antagonist pre-treated mice. The results revealed that i.c.v. administration of lower doses of anandamide (1-10 μg/mouse) or its analogues (AM404 or URB597; 1-5 μg/mouse) inhibited MBB indicating the anticompulsive activity. Conversely, at higher doses (40 or 20 μg/mouse) these compounds increased MBB similar to capsaicin (TRPV1 agonist, 100 μg/mouse) exhibiting a pro-compulsive effect. Pretreatment with AM251 (CB(1) antagonist, 1 μg/mouse) antagonized the anticompulsive effect of these compounds, while their pro-compulsive effect at higher doses was attenuated by inactive dose of capsazepine (TRPV1 antagonist, 10 μg/mouse). However, capsazepine per se at a higher dose (100 μg/mouse) inhibited MBB. When given daily for 14 days, the anticompulsive effect of anandamide and its analogues gradually disappeared, whereas capsazepine either alone or with URB597 produced consistent inhibition of MBB comparable to fluoxetine. Thus, the study indicates the biphasic influence of anandamide on MBB, and chronic administration of capsazepine either alone or with URB597 might be an effective tool in the treatment of OCD.
Article
For the obsessive compulsive disorder (OCD) patients refractory to selective serotonin reuptake inhibitors (SSRIs), atypical antipsychotics, such as risperidone, or olanzapine have been found effective in the augmentation of SSRIs. However these atypical antipsychotics may cause a number of safety concerns associated with body weight or metabolic changes. We sought to investigate the efficacy and safety of a novel atypical neuroleptic aripiprazole as an augmenting agent for the treatment-resistant OCD. Eleven patients who had previously been assessed as poorer responders (<10% reduction of Y-BOCS) to both adequate SSRI monotherapy such as fluvoxamine or paroxetine and the subsequent atypical antipsychotic augmentation of SSRIs were included in this study. The addition of aripiprazole to ongoing SSRIs was continued for at least 12 weeks in the subjects except for one who dropped out during the period. The mean maximum daily dosage of aripiprazole in the completers was 10.9 ± 3.4 mg/day. Seven of 10 completers exhibited significant reduction of Y-BOCS (>35%) accompanying a few adverse events. This preliminary study supports the notion that adding aripiprazole to SSRIs could be a valid and effective strategy for treatment-resistant OCD patients. Thus it points towards the need of further controlled and longitudinal studies.
Article
Many schizophrenic patients have comorbid obsessive-compulsive syndromes (OCS) frequently associated with antiserotonergic second-generation antipsychotics such as clozapine and olanzapine. Whereas cognitive behavioral therapy and antiobsessive antidepressants brought up inconsistent results, pharmacological add-on strategies were able to alleviate OCS. One suggestive agent for antiobsessive add-on treatment is aripiprazole, a partial agonist at dopamine and serotonin receptors. Here, we summarize the course of a patient with paranoid schizophrenia. She developed OCS during long-term treatment with olanzapine at 20 mg/d over a period of 10 years. Baseline assessment showed severe obsessions (Yale Brown Obsessive Compulsive Scale (YBOCS) subscale score : 13) and compulsions (YBOCS subscale score : 10), whereas the psychotic syndrome was compensated (Positive and Negative Syndrome Scale, 11/17/28). The combination with aripiprazole (15 mg/) over a period of 12 weeks resulted in a marked improvement of OCS (YBOCS, 8/3) and some further improvement of the psychotic symptoms (Positive and Negative Syndrome Scale, 9/13/27). This observation points toward an antiobsessive potency of aripiprazole in combination with olanzapine, quite similar to approaches involving clozapine. Hence, the proposed strategy should be further evaluated in prospective controlled trials.
Article
Obsessive-compulsive disorder (OCD) is a common and often debilitating neuropsychiatric condition characterized by persistent intrusive thoughts (obsessions), repetitive ritualistic behaviors (compulsions) and excessive anxiety. While the neurobiology and etiology of OCD has not been fully elucidated, there is growing evidence that disrupted neurotransmission of glutamate within corticalstriatal-thalamocortical (CSTC) circuitry plays a role in OCD pathogenesis. This review summarizes the findings from neuroimaging, animal model, candidate gene and treatment studies in the context of glutamate signaling dysfunction in OCD. First, studies using magnetic resonance spectroscopy are reviewed demonstrating altered glutamate concentrations in the caudate and anterior cingulate cortex of patients with OCD. Second, knockout mouse models, particularly the DLGAP3 and Sltrk5 knockout mouse models, display remarkably similar phenotypes of compulsive grooming behavior associated with glutamate signaling dysfunction. Third, candidate gene studies have identified associations between variants in glutamate system genes and OCD, particularly for SLC1A1 which has been shown to be associated with OCD in five independent studies. This converging evidence for a role of glutamate in OCD has led to the development of novel treatment strategies involving glutamatergic compounds, particularly riluzole and memantine. We conclude the review by outlining a glutamate hypothesis for OCD, which we hope will inform further research into etiology and treatment for this severe neuropsychiatric condition.
Article
Obsessive compulsive disorder is prevalent, disabling, incompletely understood, and often resistant to current therapies. Established treatments consist of specialized cognitive-behavioral psychotherapy and pharmacotherapy with medications targeting serotonergic and dopaminergic neurotransmission. However, remission is rare, and more than a quarter of OCD sufferers receive little or no benefit from these approaches, even when they are optimally delivered. New insights into the disorder, and new treatment strategies, are urgently needed. Recent evidence suggests that the ubiquitous excitatory neurotransmitter glutamate is dysregulated in OCD, and that this dysregulation may contribute to the pathophysiology of the disorder. Here we review the current state of this evidence, including neuroimaging studies, genetics, neurochemical investigations, and insights from animal models. Finally, we review recent findings from small clinical trials of glutamate-modulating medications in treatment-refractory OCD. The precise role of glutamate dysregulation in OCD remains unclear, and we lack blinded, well-controlled studies demonstrating therapeutic benefit from glutamate-modulating agents. Nevertheless, the evidence supporting some important perturbation of glutamate in the disorder is increasingly strong. This new perspective on the pathophysiology of OCD, which complements the older focus on monoaminergic neurotransmission, constitutes an important focus of current research and a promising area for the ongoing development of new therapeutics.
Article
The transient receptor potential vanilloid type 1 channel (TRPV1; originally vanilloid receptor VR1) is activated in peripheral terminals of nociceptive fibers by noxious heat, low pH, and natural products such as capsaicin, the pungent ingredient of red-hot chilli peppers. Evidence has been accumulating that TRPV1 is expressed also in the brain, where it seems to be involved in antinociception, locomotor control, and regulation of affective behaviors. This ion channel might be activated by arachidonoyl ethanolamide (anandamide), the endogenous agonist of the cannabinoid type 1 (CB(1)) receptor. However, while CB(1) activation leads to a decrease in intracellular calcium and attenuation of synaptic transmission, anandamide binding to TRPV1 results in elevated calcium levels and potentiated synaptic transmission. This suggests a tripartite regulatory system with antagonistic effects of CB(1) and TRPV1, which are tied together by the same endogenous ligand. Such a system may have important implication for the modulation of behavioral responses. The present commentary elaborates on this interplay between CB(1) receptors and TRPV1 channels in the context of fear- and anxiety-related behaviors.
Article
To explore associated clinical factors in children with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). Children with tics, obsessive-compulsive disorder, or both (n=109) were examined with personal and family history, diagnostic interview, physical examination, medical record review, and measurement of baseline levels of streptococcal antibodies. Significant group differences were found on several variables, such that children in whom PANDAS (versus without PANDAS) were more likely to have had dramatic onset, definite remissions, remission of neuropsychiatric symptoms during antibiotic therapy, a history of tonsillectomies/adenoidectomies, evidence of group A streptococcal infection, and clumsiness. The identification of clinical features associated with PANDAS should assist in delineating risks for this subtype of obsessive-compulsive disorder/tics.
Article
Once considered rare and resistant to treatment, obsessive-compulsive disorder (OCD) has now emerged as a common, yet often unrecognized, psychiatric condition. Treatment with selective serotonin reuptake inhibitors (SSRIs) is effective in 40–60% of patients with OCD. Management of the remaining 40–60% of patients with treatment-resistant OCD is challenging. We review up-to-date evidence focusing on strategies for treatment-resistant OCD, including increasing the dose of SSRI, switching to another SSRI, augmentation with antipsychotics, and the use of serotonin nor-adrenaline (norepinephrine) reuptake inhibitors (SNRIs) and monoamine oxidase inhibitors (MAOIs). Finally, we provide a flow chart, which includes nonpharmacological interventions such as cognitive-behavioural therapy, family interventions and physical interventions such as neurosurgery and deep brain stimulation, alongside the pharmacological strategies.
Article
Endocannabinoid analogues exhibit antidepressant and anti-compulsive like effects similar to that of serotonin selective reuptake inhibitors (SSRIs) indicating a parallelism between the effects of serotonin and endocannabinoids. Therefore, the present study was designed to investigate the role of endocannabinoids in the antidepressant and anti-compulsive like effect of fluoxetine using mice model of forced swim test (FST) and marble-burying behavior (MBB). The results revealed that intracerebroventricular injections of endocannabinoid analogues, anandamide, a CB(1) agonist (AEA: 1-20 μg/mouse); AM404, an anandamide transport inhibitor (0.1-10 μg/mouse); and URB597, a fatty acid amide hydrolase inhibitor (0.05-10 μg/mouse) produced antidepressant-like effect dose-dependently, whereas influenced the MBB in a biphasic manner (produced a U-shaped dose-response curve). Fluoxetine (2.5-20 mg/kg, i.p.) dose dependently decreased the immobility time as well as burying behavior. Co-administration of sub-effective dose of fluoxetine (2.5 mg/kg, i.p.) potentiated the effect of sub-effective dose of AEA (0.5 μg/mouse, i.c.v.), AM404 (0.05 μg/mouse, i.c.v) or URB597 (0.01 μg/mouse, i.c.v) in both the paradigms. Interestingly, pretreatment with AM251, a CB(1) antagonist, blocked the effect of fluoxetine in FST and MBB at a dose (1 μg/mouse, i.c.v) that per se had no effect on either parameter. Similar effects were obtained with endocannabinoid analogues in AM251 pretreated mice. However, AM251 increased the burying behavior in MBB at a highest dose tested (5 μg/mouse). None of the treatments had any influence on locomotor activity. Thus, the study indicates an interaction between endocannabinoid and serotonergic system in regulation of depressive and compulsive-like behavior.
Article
The atypical antipsychotic, quetiapine, is frequently prescribed on-label and off-label for the treatment of a variety of psychiatric disorders. As quetiapine has variable affinity for dozens of receptors, its clinical effects should also show a large variation as a function of dose and diagnostic category. This study attempts to elucidate the dose-response and comparative efficacy and tolerability (metabolic data) of quetiapine across psychiatric disorders. A systematic search was carried out in the electronic databases, PubMed and EMBASE, using the keywords 'quetiapine' and 'placebo'. Both monotherapy and add-on studies were included. A total of 41 studies were identified. In unipolar and bipolar depression, studies consistently found quetiapine to be effective versus placebo, at doses of approximately 150-300 and 300-600 mg per day, respectively. In bipolar mania, they consistently found quetiapine to be effective at doses of approximately 600 mg per day. In acute exacerbation of schizophrenia, the majority of studies found quetiapine to be effective at doses of approximately 600 mg per day; however, a few large studies found no difference versus placebo. In contrast, studies consistently found quetiapine to be more effective than placebo for stable schizophrenia. In obsessive-compulsive disorder, studies did not consistently find quetiapine to be effective at doses of approximately 300 mg per day. However, studies may have underestimated the efficacy of quetiapine for obsessive-compulsive disorder due to concomitant administration of antidepressants and the utilization of treatment-refractory patients. In generalized anxiety disorder, studies consistently found quetiapine to be effective at doses of approximately 150 mg per day. Finally, analysis of metabolic tolerability data suggests that even low doses of quetiapine may lead to increase in weight and triglycerides across psychiatric disorders. Interestingly, however, quetiapine-induced elevations in low-density lipoprotein and total cholesterol seem to be restricted to schizophrenia patients.
Article
A key to advancing the understanding of obsessive-compulsive disorder (OCD)-like symptoms is the development of spontaneous animal models. Over 55 generations of bidirectional selection for nest-building behavior in house mice, Mus musculus, resulted in a 40-fold difference in the amount of cotton used for a nest in high (BIG) and low (SMALL) selected lines. The nesting behavior of BIG mice appears to be compulsive-like and has initial face validity as an animal model for OCD in humans. Compulsive-like digging behavior was assessed; BIG male mice buried about three times as many marbles as SMALL male mice, strengthening face validity. Using the open field and elevated plus maze, SMALL male mice showed higher levels of anxiety/fear-like behavior than BIG male mice, indicating that compulsive-like and not anxiety-like behavior was measured. To establish predictive validity, chronic (4 weeks) oral administration of fluoxetine (30, 50 and 100mg/kg/day) and clomipramine (80 mg/kg/day), both effective in treating OCD, significantly reduced compulsive-like nest-building behavior in BIG male mice. Compulsive-like digging behavior was also significantly reduced by chronic oral fluoxetine (30 and 80 mg/kg/day) treatment in BIG male mice. General locomotor activity was not affected by chronic oral fluoxetine (30 and 80 mg/kg/day) treatment; chronic oral treatment with desipramine (30 mg/kg/day), an antidepressant not effective in treating OCD, had no effect on nesting behavior of BIG male mice, strengthening predictive validity. Together, the results indicate that these mice have good face and predictive validity as a non-induced mouse model of compulsive-like behavior relevant to OCD.
Article
Obsessive-compulsive disorder (OCD) is a disabling neuropsychiatric disorder. Two treatments have been proven efficacious for the symptoms of OCD: pharmacological treatment with serotonin reuptake inhibitors and cognitive-behavioral therapy (CBT) consisting of exposure and response prevention. This chapter will focus on pharmacological treatments. The only medications which have proved effective for OCD in multisite randomized controlled trials are serotonin reuptake inhibitors, which include clomipramine (a noradrenergic and serotonergic reuptake inhibitor) and the selective serotonin reuptake inhibitors. General guidelines for the use of these medication will be presented, focusing on key issues that arise in clinical practice such as what dose to use, time to response, management of side effects, and duration of treatment. Because many OCD patients will have either a partial response or no response to these medications, evidence-based strategies for managing both partial responders and nonresponders will be described, including the evidence supporting augmentation with other medications or with CBT, and switching to other medications. Finally, novel strategies which are based on an increased understanding of the brain mechanisms underlying OCD and which are under investigation will be reviewed.
Article
Cannabinoids have long been shown to have a range of potential therapeutic effects, including antiemetic actions, analgesia, and anxiolysis. However, psychomimetic and memory disruptive side effects, as well as the potential for abuse and dependence, have restricted their clinical development. Endogenous cannabinoids (i.e., endocannabinoids; eCBs), such as anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are produced throughout the limbic system and other brain regions associated with emotionality and are believed to modulate behavioral responses to stress-related conditions. AEA and 2-AG are rapidly metabolized by the respective enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Accordingly, inhibition of each enzyme increases brain levels of the appropriate eCB. Although FAAH inhibition has been established to decrease anxiety-like behavior, the role of 2-AG has been difficult to ascertain until the recent synthesis of JZL184, a potent and selective MAGL inhibitor. In the present study, we investigated the effects of inhibiting FAAH or MAGL on anxiety-like behavior in marble burying, a model of repetitive, compulsive behaviors germane to anxiety disorders such as obsessive-compulsive disorder. The FAAH inhibitor PF-3845, the MAGL inhibitor JZL184, and the benzodiazepine diazepam decreased marble burying at doses that did not affect locomotor activity. In contrast, Δ9-tetrahydrocannabinol (THC), the primary psychoactive constituent of marijuana, did not consistently reduce marble burying without also eliciting profound decreases in locomotor behavior. The CB1 cannabinoid receptor antagonist rimonabant blocked the reduction in marble burying caused by FAAH and MAGL inhibitors, but not by diazepam, indicating a CB1 receptor mechanism of action. These data indicate that elevation of AEA or 2-AG reduces marble burying behavior and suggest that their catabolic enzymes represent potential targets for the development of new classes of pharmacotherapeutics to treat anxiety-related disorders.
Article
Cannabidiol (CBD) is a major non-psychotomimetic component of Cannabis sativa that has been shown to have an anxiolytic effect in human and animal models. Earlier studies suggest that these effects involve facilitation of serotonin, a neurotransmitter that has also been related to obsessive-compulsive disorder. On the basis of this evidence, this study investigated the effects of CBD in C57BL/6J mice submitted to the marble-burying test (MBT), an animal model proposed to reflect compulsive behaviour. CBD (15, 30 and 60 mg/kg) induced a significant decrease in the number of buried marbles compared with controls (34, 41 and 48%, respectively). A similar, although larger, decrease was also found after the serotonin selective reuptake inhibitor paroxetine (10 mg/kg, 77% decrease) and the benzodiazepine diazepam (2.5 mg/kg, 84% decrease). The effect of CBD (30 mg/kg) was still significant after 7 days of daily repeated administration, whereas the effect of diazepam disappeared. Pretreatment with WAY100635 (3 mg/kg), a 5HT1A receptor antagonist, prevented the effects of paroxetine but failed to alter those of CBD. These latter effects, however, were prevented by pretreatment with the CB1 receptor antagonist AM251 (1 mg/kg). These results indicated that CBD and paroxetine decrease the number of buried marbles in the MBT through distinct pharmacological mechanisms. They also suggest a potential role of drugs acting on the cannabinoid system in modulating compulsive behaviour.
Article
Cannabis use during adolescence is associated with an increased risk for schizophrenia and other disorders. The neuronal basis is unclear, but prefrontal cortical mechanisms have been implicated. Here, we investigated developmental changes in the endocannabinoid system by assessing expression and function of the CB1 cannabinoid receptor in prefrontal and other cortical areas in juvenile (postnatal day 25, P25), adolescent (P40), and adult (P70) rats. Overall, the expression of CB1 receptors in the cortex is highest in juveniles and drops thereafter toward adult levels. However, CB1 receptor expression follows distinct developmental trajectories in different cortical areas. The most pronounced and progressive decrease in CB1 expression was observed in medial prefrontal and other limbic/associative regions. In contrast, major changes in sensorimotor cortices occurred only after P40. We also assessed electrophysiological measures of CB1 receptor function and found that CB1-dependent inhibition of synaptic transmission in the prefrontal cortex follows the same developmental trajectory as observed for receptor expression. Together, these findings indicate that CB1 receptor-mediated signaling decreases during development but is differentially regulated in limbic/associative vs. sensorimotor systems. Therefore, cannabis use during adolescence likely differentially affects limbic/associative and sensorimotor cortical circuits.
Article
Repetitive and stereotyped behavior is a prominent element of both animal and human behavior. Similar behavior is seen across species, in diverse neuropsychiatric disorders and in key phases of typical development. This raises the question whether these similar classes of behavior are caused by similar neurobiological mechanisms or whether they are neurobiologically unique? In this paper we discuss fundamental animal research and translational models. Imbalances in corticostriatal function often result in repetitive behavior, where different classes of behavior appear to be supported by similar neural mechanisms. Although the exact nature of these imbalances are not yet fully understood, synthesizing the literature in this area provides a framework for studying the neurobiological systems involved in repetitive behavior.
Article
Accumulating evidence has implicated glutamatergic systems in psychiatric disorders. Abnormalities in glutamatergic systems have consistently been identified in obsessive-compulsive disorder (OCD). Marble-burying behavior has been described in literature as a potentially useful measure for modeling OCD in mice. However, involvement of glutamatergic systems in marble-burying behavior has largely remained unexplored. Here, the effects of an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor potentiator, CX546, and an NR2B subunit-containing N-methyl-D-aspartate (NMDA) receptor antagonist, Ro25-6981, were examined using a marble-burying test. Treatment with highest dose (30.0mg/kg) of CX546 significantly inhibited the marble-burying behavior. Moreover, treatment with Ro25-6981 also significantly reduced the marble-burying behavior. In contrast, both drugs did not affect locomotor activity in mice. The present results suggest that glutamatergic systems might be related to marble-burying behavior. Furthermore, agents targeting glutamateric systems such as an AMPA receptor potentiator and an NR2B receptor antagonist, may be useful in treating OCD.
Article
An increasing number of investigators utilize the marble-burying assay despite the paucity of information available regarding what underlies the behavior. We tested the possibility that a genetic component underlies marble burying in mice and if there is a genetic correlation with other anxiety-like traits. Since findings reported in the literature indicate that marble-burying behavior reflects an anxiety-like response, we explored the assumption that the novel nature of a marble induces this anxiety. Finally, we investigated how the natural response of a mouse to dig relates to the marble-burying phenomenon. We examined ten different inbred mouse strains to determine if marble-burying behavior is genetically regulated and correlated with anxiety-like traits in two other assays. We employed multiple variants of the "traditional" marble-burying assay to address how issues such as the novelty of marbles and digging behavior contribute to marble burying. Marble-burying behavior varied across strain and did not correlate with anxiety measures in other assays. Multiple tests conducted to reduce the novelty of marbles failed to alter burying behavior. Additionally, digging behavior correlated with marble burying, and the presence of marbles did not significantly impact the digging response. Our results indicate that mouse marble burying is genetically regulated, not correlated with other anxiety-like traits, not stimulated by novelty, and is a repetitive behavior that persists/perseveres with little change across multiple exposures. Marble burying is related to digging behavior and may in fact be more appropriately considered as an indicative measure of repetitive digging.
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Cannabidiol (CBD) is a non-psychotomimetic compound from Cannabis sativa which induces anxiolytic- and antipsychotic-like effects in rodents. These effects could be mediated by facilitation of the endocannabinoid system or by the activation of 5-HT(1A) receptors. As either of these mechanisms could promote adaptation to inescapable stress, the aim of the present work was to test the hypothesis that CBD would attenuate the autonomic and behavioural consequences of restraint stress (RS). We also investigated if the responses to CBD depended on activation of 5-HT(1A) receptors. Male Wistar rats received i.p. injections of vehicle or CBD (1, 10 or 20 mg kg(-1)) and 30 min later were submitted to 60 min of restraint where their cardiovascular responses were recorded. The protocol of the second experiment was similar to the first one except that animals received i.p. injections of the 5-HT(1A) receptor antagonist WAY100635 (0.1 mg kg(-1)) before CBD treatment and exposure to restraint. 24 h later they were also tested in the elevated plus-maze (EPM), an animal model of anxiety. Exposure to RS increased blood pressure and heart rate and induced an anxiogenic response in the EPM 24 h later. These effects were attenuated by CBD. WAY100635 by itself did not change the cardiovascular and anxiogenic response to RS, but blocked the effects of CBD. The results suggest that CBD can attenuate acute autonomic responses to stress and its delayed emotional consequences by facilitating 5-HT(1A) receptor-mediated neurotransmission.
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Transient receptor potential vanilloid 1 (TRPV1) channels participate in the modulation of synaptic transmission in the periphery and in central structures. Here, we investigated the role of TRPV1 channels in the control of both excitatory and inhibitory transmission in the striatum. Pharmacological stimulation of TRPV1 channels with capsaicin (10 nM) selectively enhanced the frequency of glutamate-mediated spontaneous (sEPSCs) and miniature excitatory postsynaptic currents (mEPSCs) recorded from putative striatal medium spiny neurons. Capsaicin-mediated response underwent a rapid rundown, and was no longer detected in the majority of the neurons when the concentration of the drug was in the micromolar range, possibly due to receptor desensitization. Consistently, the totality of striatal neurons responded to capsaicin (10 nM or 10 microM) after prevention of desensitization of TRPV1 channels with the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA). PMA was able per se to increase sEPSC frequency. The effects of capsaicin and of PMA were absent after pharmacological or genetic inactivation of TRPV1 channels. Finally, we provided evidence for anandamide as an endovanilloid substance in the striatum, since genetic inhibition of anandamide degradation resulted in a tonic activation of TRPV1 channels modulating glutamate but not GABA release. TRPV1-mediated regulation of excitatory transmission in the striatum might be important for the final output to other basal ganglia structures, and might play a role in several physiological and pathological processes.