Psychopharmacology

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Online ISSN: 1432-2072
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Article
  • Kristen N. AmicoKristen N. Amico
  • Miranda E. ArnoldMiranda E. Arnold
  • Morgan S. DourronMorgan S. Dourron
  • [...]
  • Jesse R. SchankJesse R. Schank
RationaleAlthough polysubstance use is highly prevalent, preclinical studies that assess voluntary consumption of multiple substances at the same time are rather uncommon. Overlooking drug taking patterns commonly observed in humans may limit the translational value of preclinical models.Objectives Here, we aimed to develop a model of polysubstance use that could be used to assess oral operant self-administration patterns under concurrent access to alcohol and the prescription opioid oxycodone.Methods After a training period where animals associated specific cues and levers with each drug, rats self-administered alcohol and oxycodone solutions concurrently in daily sessions. Oxycodone was then removed to assess potential changes in alcohol consumption. The role of cues and stress on alcohol consumption and oxycodone seeking was also examined under reinstatement conditions.ResultsWe found that females consumed more alcohol and oxycodone than males when given access to both drugs, and this effect on alcohol intake persisted when oxycodone was removed. Additionally, re-exposure to oxycodone cues in combination with the administration of the pharmacological stressor yohimbine drove reinstatement of oxycodone seeking in females but did not have a strong effect in males, possibly due to low levels of oxycodone intake during active self-administration in male rats. Additionally, yohimbine drove increased alcohol consumption, in line with prior findings from our group and others.Conclusions Taken together, this study demonstrates that rats will concurrently self-administer both oxycodone and alcohol in operant chambers, and this procedure can serve as a platform for future investigations in polysubstance use and relapse-like behavior.
 
Fentanyl reinstatement to discriminative cues after conflict in sign- and goal-tracking rats. A Experimental timeline. B–D Pavlovian conditioned approach training: B overall PCA tracking score, C lever contacts, D food cup contacts
Fentanyl motivated behavior for all rats combined. A Fentanyl self-administration through acquisition (five sessions) and DS training phases (ten sessions). B Rates of responding in the DS + and DS– components of DS training sessions, binned by the first five and last five sessions of DS discrimination phase. C Day 15 of DS training. Data are binned into 1 min segments across the 25 min DS– component and 5 min DS + component, and the resulting data are averaged across all DS–/DS + cycles across the session. Inset shows the individual data for the transition between the last bin of the DS– component and the first bin of the DS + component (**p < 0.01, paired t-test). D Conflict extinction behavior in the presence of electrified floor barrier in front of nosepokes. E Poking rates (inactive/active) for the last conflict extinction test (left two columns) and reinstatement test (right two columns). F Poking rates (DS–/DS +) for the last conflict extinction test (left two columns) and reinstatement test (right two columns). G Reinstatement test poking rate data binned into 30 s segments across the 2.5 min DS– component and 30 s DS + component. Data are averaged across all DS–/DS + cycles in session. Inset shows the individual data for the transition between the last bin of the DS– component and the first (only) bin of the DS + component (***p < 0.001, paired t-test)
Fentanyl acquisition and DS training by tracking group and sex. A Fentanyl self-administration through acquisition (five sessions) and DS training phases (ten sessions) by tracking group. B Fentanyl self-administration through acquistion and DS training by sex. C Rates of responding in the DS + and DS– components of DS training sessions, binned by the first five and last five sessions of DS discrimination phase by tracking. D Rates of responding in the DS + and DS– components of DS training sessions binned by the first five and last five sessions of DS discrimination phase by sex
Conflict extinction behavior by tracking group and sex. A Conflict extinction infusions by tracking. B Conflict extinction active pokes by tracking. C Average shock intensity used across sessions by tracking. D Conflict extinction infusions by sex. E Conflict extinction active pokes by sex. F Average shock intensity used across sessions by sex
Reinstatement behavior by tracking group and sex. A Active side poking rates during final conflict session (left) and reinstatement test (right) by tracking. B DS + poking rates during final conflict session (left) and reinstatement test (right) by tracking. C Linear correlation between PCA score and active poking rate (R² = .1023, p = 0.0971). D Active side poking rates during final conflict session (left) and reinstatement test (right) by sex. E DS + poking rates during final conflict session (left) and reinstatement test (right) by sex. F Reinstatement DS scores by tracking (left, black bars) and by sex (right, gray bars) (‘*’ indicates p = 0.037, t-test)
Article
  • David A. MartinDavid A. Martin
  • Sara E. KeeferSara E. Keefer
  • Donna J. CaluDonna J. Calu
Rationale Discriminative stimuli (DS) are cues that predict reward availability. DS are resistant to extinction and motivate drug seeking even after long periods of abstinence. Previous studies have demonstrated that sign-tracking (ST) and goal-tracking (GT) differences in Pavlovian approach predict distinct cue-modulated vulnerabilities to cocaine reinstatement. GT rats show heightened reinstatement to contextual and DS, while ST rats show heightened reinstatement to discrete stimuli. Here we examine whether DS modulate reinstatement after electric barrier-induced abstinence and whether tracking-related relapse vulnerabilities generalize to opioid relapse. Objectives We examine whether DS-modulated reinstatement to fentanyl seeking persists in the presence of reduced adverse consequences after electric barrier-induced abstinence. We also examine whether tracking differences predict the magnitude of DS-modulated reinstatement of fentanyl seeking after electric barrier-induced abstinence. Methods We used Pavlovian lever autoshaping (PLA) training to determine sign-, goal-, and intermediate tracking groups in male and female Sprague Dawley rats. We then trained rats in a DS model of intermittent fentanyl self-administration, and extinguished drug seeking by imposing an electric barrier of increasing intensity. We then measured the level of DS-modulated reinstatement in the presence of a reduced electric barrier intensity. Results We report that DS strongly modulate fentanyl seeking after electric barrier-induced abstinence. DS–modulation of fentanyl acquisition, electric barrier-induced abstinence, and reinstatement was similar for sign- and goal-tracking groups. Conclusions Discriminative stimuli powerfully motivate opioid seeking, despite continued aversive consequences. Pavlovian approach differences do not predict the level of DS-modulated reinstatement to fentanyl seeking after conflict-induced abstinence.
 
Article
Rationale Stressful events can have lasting and impactful effects on behavior, especially in terms of appropriate fear regulation and reward seeking. Our prior work in rats has shown baseline sex differences in fear expression and sucrose seeking in a discriminative reward-fear-safety conditioning task. Objectives The objectives of the current study were to determine how prior stress may affect alcohol consumption across a reward-fear-safety learning task, and how prior alcohol history may interact with stress to impact learning in this task. Methods Male and female Long Evans rats were given home cage intermittent 24 h access to both water and alcohol for 5 weeks. A subset of rats then received exposure to stress (15 unsignaled footshocks), while remaining unstressed rats received context exposure without shock. One week later, all rats were trained on the same reward-fear-safety cue task while having continuous home cage access to both water and alcohol. Results All rats increased consumption (g/kg/24 h) across the 5 weeks of intermittent access, with females showing higher consumption levels. Stress exposure did not alter alcohol consumption in the week following stress, but did increase home cage alcohol consumption during later reward-fear-safety cue learning. Stress in both sexes also elevated freezing levels to the reward cue resulting in decreased sucrose seeking and was positively correlated with home cage alcohol consumption. Conclusions While stress increased drinking in both males and females, the effects of stress were particularly pronounced in females, indicating our results could be capturing a higher propensity for females to display stress-induced drinking.
 
Scatterplot of buprenorphine elimination rate constant and percentage negative opioid screens
Article
Background Opioid craving is suggested to correlate with the rate of reduction in buprenorphine (BUP) plasma levels. No studies explored Buprenorphine elimination rate constant (BUP EL.R) as a predictor of opioid use or retention in BUP treatment. Methods Analysis was performed using data from a randomized controlled trial of 141 adults with opioid use disorder (OUD) randomized to Incentivized Adherence and Abstinence monitoring (I-AAM; experimental (n = 70) and treatment-as-usual; control (n = 71). In the I-AAM, structured access to unsupervised BUP doses was provided up to 28 days contingent of adherence measured by Therapeutic Drug Monitoring and abstinence by Urinary Drug Screens (UDS). In contrast, the treatment-as-usual (control) provided unstructured access to unsupervised doses was provided for up to 14 days considering UDS results. The primary outcome was percentage negative UDS. The secondary outcome, retention in treatment, was continuous enrollment in the study and analysis was via intention-to-treat. Significant bivariate correlations with the outcomes were adjusted for group allocation. Results A significant negative correlation between BUP EL.R and percentage negative opioid screens (Pearson correlation coefficient − 0.57, p < 0.01) was found. After adjusting for trial group, BUP EL.R was shown to be an independent predictor of percentage negative opioid screens (Standardized Beta Coefficient − 0.57, 95% CI − 221.57 to − 97.44, R² 0.322). Conclusion BUP EL.R predicted 32.2% of the variation in percentage negative opioid UDS and may serve as a potential promising tool in precision medicine of BUP treatment. Higher buprenorphine elimination is associated with higher positive opioid urine screens during treatment. Trial registration ISRCTN41645723 retrospectively registered on 15/11/2015.
 
Article
Rationale Alcohol consumption is a common antecedent of aggressive behavior. The effects of alcohol on the decision to engage in aggression in preference over pro-social interaction are hypothesized to arise from augmented function within the medial prefrontal cortex (mPFC). Objective In a newly developed procedure, we studied social decision-making in male C57BL/6 J mice based on preferentially seeking access to either sociosexual interactions with a female partner or the opportunity to attack an intruder male. While deciding to engage in aggressive vs. sociosexual behavior, corresponding neural activation was assessed via c-Fos immunoreactivity in cortical, amygdaloid and tegmental regions of interest. A further objective was to investigate how self-administered alcohol impacted social choice. Methods During repeated confrontations with an intruder male in their home cage, experimental mice engaged in species-specific sequence of pursuit, threat, and attack behavior within < 2 min. Mice were then conditioned to respond at one of two separate illuminated operanda in an experimental chamber (octagon) attached to their home cage; completion of 10 responses (fixed ratio 10; FR10) was reinforced by access to either a female or a male intruder which were presented in the resident’s home cage. Brains were harvested following choice between the concurrently available aggressive and sociosexual options and processed for c-Fos immunoreactivity across 10 brain regions. In two separate groups, mice were trained to rapidly self-administer ethanol prior to a social choice trial in order to examine the effects of alcohol on social choice, sociosexual, aggressive acts and postures, and concurrent c-Fos activity in the mPFC and limbic regions. Results and discussion Eight out of 65 mice consistently chose to engage in aggressive behavior in preference to sociosexual contact with a female when each outcome was concurrently available. Self-administered alcohol (experiment 1: 1.2 ± 0.02 g/kg; experiment 2: 0, 1.0, 1.5, and 1.8 g/kg) increased responding for the aggressive option in mice that previously opted predominantly for access to sociosexual interactions with the female. When choosing the aggressive, but not the sociosexual option, the prelimbic area of the mPFC revealed increased c-Fos activity, guiding future detailed inquiry into the neural mechanisms for aggressive choice.
 
Experiment timeline. Simplified flow chart of the experimental design
Heroin self-administration. Mean (± SEM) of seek lever presses and number of infusions over training days, for short punishment group (N = 26) and long punishment (N = 18). *p < .05 long compared to short punishment period. FR: fixed ratio schedule of reinforcement, VI: variable interval schedule of reinforcement
Punishment-imposed abstinence. Mean (± SEM) seek lever responses and infusions (insert) over punishment days. a Short punishment-period group (N = 26). b Long punishment-period group (N = 18). *p < .05 compared to baseline. Baseline was calculated as the mean of the infusions or seek lever responses over the training days under VI60
Food-deprivation-induced heroin relapse tests. Mean (± SEM) seek lever (a) and take lever (b) presses made during the 3 h heroin relapse tests under food deprivation and sated conditions, for short (N = 24) and long punishment-period (N = 18) groups. * p < .0001, food deprived compared to sated
Detailed punishment phase behaviour analyses. a Mean (± SEM) difference score of the latency to press the seek lever before (pre-shock) and after (post-shock) a shock trial over the punishment sessions in minutes. *p < .05 compared to 0.2 mA. b Mean (± SEM) latency, in minutes, to the first seek lever press per session. Data points at 10 min indicate a complete omission of pressing the seek lever in the session. *p < .05 compared to baseline. c Mean (± SEM) latency in minutes to first seek lever presses from every trial in each punishment day. *p < .05 compared to baseline. d Mean (± SEM) latency in minutes between the final seek lever press in a VI and the following take lever press over punishment days. e Mean (± SEM) seek presses made during the VI in each trial, over punishment days. *p < .05 compared to baseline. f Mean (± SEM) ratio of first-seek response omissions out of total trials in a ‘half-session’ over punishment days. Each session is divided into two 3 h segments. *p < .05 1st compared to 2nd half-session; #p < .05 compared to baseline. g Mean (± SEM) ratio of omissions due to uncompleted seek links out of total trials in a session. *p < .05 compared to baseline. h Mean (± SEM) ratio of omitted take lever responses out of the total number of initiated take links in a session. Baseline in all figures represents the average of the relevant variable over the VI60 self-administration training days
Article
Rational Stress is a major trigger for drug relapse in humans and animal models, even after prolonged abstinence. However, animal models for stress-induced relapse were criticized for the lack of predictive and face validity. Objectives Here we investigated the effect of acute food deprivation stress in a novel stress-induced relapse model using voluntary, punishment-imposed abstinence from heroin. We also performed a detailed characterization of the development of punishment-imposed abstinence. Methods Male rats were trained to self-administered heroin (0.1 mg/kg/infusion) for 2 weeks, using the seeking-taking chained schedule. Pressing the ‘seeking’ lever led to the insertion of the ‘taking’ lever and pressing the take lever resulted in heroin infusion. Following self-administration training, rats were exposed to 8 or 21 days of heroin-seeking punishment. During punishment, 30% of the completed seek links resulted in a mild escalating footshock instead of take lever presentation. Next, rats were tested for heroin seeking under extinction conditions after 24 h of food deprivation and sated conditions. Results Probabilistic punishment of seeking lever responses resulted in gradual suppression of heroin seeking and taking. Exposure to food-deprivation stress induced a robust relapse to heroin seeking after short and long punishment-imposed abstinence periods, without significant effects of time, i.e., no incubation of heroin seeking. Individual differences were observed in the development of punishment-induced abstinence and stress-induced relapse. Conclusions These results suggest that stress is a reliable trigger to relapse even after a prolonged period of punishment-induced, voluntary abstinence.
 
Mechanism of action of Venlafaxine.5-HT and NE are stored into presynaptic vesicles. Incoming action potentials trigger their release into the synaptic cleft after melding with the cell membrane. 5-HT/NE can then bind to postsynaptic serotonergic and adrenergic G-coupled receptors. In parallel of the activation of these postsynaptic elements, 5-HT/NE can return into the presynaptic neurons through serotonin/norepinephrine transporters (SERT/NET) through a high affinity reuptake process. 5-HT/NE can also be removed from the synaptic cleft by neighboring glial cells such as astrocytes (not shown here). Into the presynaptic neuron, 5-HT and NE can penetrate into exocytosis vesicles through a vesicular monoamine transporter or degraded by the monoamine oxidase (MAO). Serotonergic and noradrenergic neurons have multiple ways to up- and downregulate monoamines response thereby maintaining a normal excitatory/inhibitory balance and protecting the brain from a sub-or over-stimulation. Receptors are not only found on the postsynaptic neuronal membrane, but also presynaptically. In particular, autoreceptors are found on axon terminals (i.e. 5HT1B and A2R) or on the soma (i.e. 5HT1A and A2R). If too many neurotransmitters accumulate in the synaptic cleft, these Gi-coupled autoreceptors are activated to mediate an inhibitory signal on the firing or release activities of the presynaptic serotonergic and adrenergic neurons. By inhibiting the SERT and NET transporters, venlafaxine can simultaneously increase extracellular 5-HT/NE levels in various brain regions involved and therefore to activate postsynaptic receptors involved in the regulation of emotional states. However, this action is limited by the recruitment of the autoreceptors after an acute administration of venlafaxine. While the treatment is prolonged, such inhibitory feedbacks desensitize thereby producing a higher rate of monoamines in the synaptic cleft necessary to promote beneficial behavioral effects.
Impact of venlafaxine on the excitatory/inhibitory (E/I) balance in the hippocampus. Stress increases perineuronal nets (PNNs) deposition around parvalbumin positive (PV+) GABAergic interneurons in the hippocampus due to the inactivation of metalloproteases (MMP) such as MMP9. This reinforces the excitatory synapses upon PV+ GABAergic interneurons thereby leading to their hyperactivity. Such a process would be associated to an increased release of GABA in the hippocampus. As PV+ GABAergic interneurons contact excitatory pyramidal cells, their hyperactivity induces a local inhibition of pyramidal cells. Overall altered E/I balance is observed in animal models of depression (left panel). Venlafaxine, through the inhibition of serotonin (5-HT) and norepinephrine (NE) reuptake, promotes the accumulation of these monoamines in the synaptic cleft. Evidence demonstrates that both 5-HT and NE favor the activity of MMP9, which in turn, leads to PNNs degradation. In that condition, the activation of PV+ GABAergic interneurons is attenuated. A decreased release of GABA is then expected causing the disinhibition of pyramidal glutamatergic neurons. As a functional consequence, the E/I balance is rescued (right panel), a process necessary for antidepressant response.
Article
Major depression (MD) is one of the most common psychiatric disorders worldwide. Currently, the first-line treatment for MD targets the serotonin system but these drugs, notably the selective serotonin reuptake inhibitors, usually need 4 to 6 weeks before the benefit is felt and a significant proportion of patients shows an unsatisfactory response. Numerous treatments have been developed to circumvent these issues as venlafaxine, a mixed serotonin-norepinephrine reuptake inhibitor that binds and blocks both the SERT and NET transporters. Despite this pharmacological profile, it is difficult to have a valuable insight into its ability to produce more robust efficacy than single-acting agents. In this review, we provide an in-depth characterization of the pharmacological properties of venlafaxine from in vitro data to preclinical and clinical efficacy in depressed patients and animal models of depression to propose an indirect comparison with the most common antidepressants. Preclinical studies show that the antidepressant effect of venlafaxine is often associated with an enhancement of serotonergic neurotransmission at low doses. High doses of venlafaxine, which elicit a concomitant increase in 5-HT and NE tone, is associated with changes in different forms of plasticity in discrete brain areas. In particular, the hippocampus appears to play a crucial role in venlafaxine-mediated antidepressant effects notably by regulating processes such as adult hippocampal neurogenesis or the excitatory/inhibitory balance. Overall, depending on the dose used, venlafaxine shows a high efficacy on depressive-like symptoms in relevant animal models but to the same extent as common antidepressants. However, these data are counterbalanced by a lower tolerance. In conclusion, venlafaxine appears to be one of the most effective treatments for treatment of major depression. Still, direct comparative studies are warranted to provide definitive conclusions about its superiority.
 
Article
Rationale The use of synthetic cannabinoid receptor agonists (SCRAs) is growing among adolescents, posing major medical and psychiatric risks. JWH-018 represents the reference compound of SCRA-containing products. Objectives This study was performed to evaluate the enduring consequences of adolescent voluntary consumption of JWH-018. Methods The reinforcing properties of JWH-018 were characterized in male CD1 adolescent mice by intravenous self-administration (IVSA). Afterwards, behavioral, neurochemical, and molecular evaluations were performed at adulthood. Results Adolescent mice acquired operant behavior (lever pressing, Fixed Ratio 1–3; 7.5 µg/kg/inf); this behavior was specifically directed at obtaining JWH-018 since it increased under Progressive Ratio schedule of reinforcement, and was absent in vehicle mice. JWH-018 IVSA was reduced by pretreatment of the CB1-antagonist/inverse agonist AM251. Adolescent exposure to JWH-018 by IVSA increased, at adulthood, both nestlet shredding and marble burying phenotypes, suggesting long-lasting repetitive/compulsive-like behavioral effects. JWH-018 did not affect risk proclivity in the wire-beam bridge task. In adult brains, there was an increase of ionized calcium binding adaptor molecule 1 (IBA-1) positive cells in the caudate-putamen (CPu) and nucleus accumbens (NAc), along with a decrease of glial fibrillary acidic protein (GFAP) immunoreactivity in the CPu. These glial alterations in adult brains were coupled with an increase of the chemokine RANTES and a decrease of the cytokines IL2 and IL13 in the cortex, and an increase of the chemokine MPC1 in the striatum. Conclusions This study suggests for the first time that male mice self-administer the prototypical SCRA JWH-018 during adolescence. The adolescent voluntary consumption of JWH-018 leads to long-lasting behavioral and neurochemical aberrations along with glia-mediated inflammatory responses in adult brains.
 
Confirmatory factor analysis model with standardised loadings. Included in the model (N = 819) were 19 items of the Watts Connectedness Scale which fulfilled loading criteria during exploratory factor analyses in a different sample (N = 407). Error terms between negatively worded items were allowed to correlate to account for method effects
Changes in connectedness following a psychedelic experience in a guided group setting. Connectedness across all subscales was significantly (p < .0001) enhanced 2 weeks, 4 weeks and 6 months following the experience compared to baseline. Error bars indicate 95% confidence intervals. CTO, connectedness to others; CTS, connectedness to self; CTW, connectedness to world; WCS, Watts’ Connectedness Scale (total)
Correlations between A mystical-type experiences, B emotional breakthrough, and C communitas and change scores on Watts Connectedness Scale (WCS) from before to after 2 weeks of a guided psychedelic group experience
Change in connectedness in a randomised controlled trial comparing escitalopram (E) and psilocybin (P) for major depression from baseline to 6 weeks (endpoint). For the complete sample, significantly greater increases in connectedness were observed. Furthermore, a significant three-way interaction indicated significantly greater increases in connectedness for psilocybin-responders, compared to escitalopram responders, whereas non-responders did not increase in connectedness in either condition. Escitalopram arm = blue, psilocybin arm = red. Baseline = light colour, endpoint = dark colour
Demographic information of both observational survey studies collected at baseline
Article
Rationale A general feeling of disconnection has been associated with mental and emotional suffering. Improvements to a sense of connectedness to self, others and the wider world have been reported by participants in clinical trials of psychedelic therapy. Such accounts have led us to a definition of the psychological construct of ‘connectedness’ as ‘a state of feeling connected to self, others and the wider world’. Existing tools for measuring connectedness have focused on particular aspects of connectedness, such as ‘social connectedness’ or ‘nature connectedness’, which we hypothesise to be different expressions of a common factor of connectedness. Here, we sought to develop a new scale to measure connectedness as a construct with these multiple domains. We hypothesised that (1) our scale would measure three separable subscale factors pertaining to a felt connection to ‘self’, ‘others’ and ‘world’ and (2) improvements in total and subscale WCS scores would correlate with improved mental health outcomes post psychedelic use. Objectives To validate and test the ‘Watts Connectedness Scale’ (WCS). Methods Psychometric validation of the WCS was carried out using data from three independent studies. Firstly, we pooled data from two prospective observational online survey studies. The WCS was completed before and after a planned psychedelic experience. The total sample of completers from the online surveys was N = 1226. Exploratory and confirmatory factor analysis were performed, and construct and criterion validity were tested. A third dataset was derived from a double-blind randomised controlled trial (RCT) comparing psilocybin-assisted therapy (n = 27) with 6 weeks of daily escitalopram (n = 25) for major depressive disorder (MDD), where the WCS was completed at baseline and at a 6-week primary endpoint. Results As hypothesised, factor analysis of all WCS items revealed three main factors with good internal consistency. WCS showed good construct validity. Significant post-psychedelic increases were observed for total connectedness scores (η2 = 0.339, p < 0.0001), as well as on each of its subscales (p < 0.0001). Acute measures of ‘mystical experience’, ‘emotional breakthrough’, and ‘communitas’ correlated positively with post-psychedelic changes in connectedness (r = 0.42, r = 0.38, r = 0.42, respectively, p < 0.0001). In the RCT, psilocybin therapy was associated with greater increases in WCS scores compared with the escitalopram arm (ηp2 = 0.133, p = 0.009). Conclusions The WCS is a new 3-dimensional index of felt connectedness that may sensitively measure therapeutically relevant psychological changes post-psychedelic use. We believe that the operational definition of connectedness captured by the WCS may have broad relevance in mental health research.
 
Article
Rationale Alcohol use disorder (AUD) is shown to have an overall heritability of around 50%. One of the genes associated with AUD is SLC6A4 (solute carrier family 6 member A4) which codes for the serotonin transporter (SERT). The study looked at serotonin dysfunction on ethanol consumption in adolescents and the subsequent intergenerational effects of drinking by using a rat model: SERT +/+ (regular functioning), SERT +/− (50% transporter reduction) and SERT −/− (complete reduction). Objectives We investigated sex and genotype differences in ethanol consumption in SERT knock-out Wistar rats (F0) followed by studying behaviour in the offspring (F1) of the male drinkers to assess effects of paternal alcohol consumption. Methods An intermittent access two-bottle choice paradigm (IA2BC) was used to yield ethanol drinking behaviour in F0 adolescent Wistar rats. The highest drinking males were mated to alcohol-naive females and their offspring were compared with controls. Drinking behaviour (IA2BC) and ethanol-induced motor coordination effects (via rotarod) were measured in the F1s. Results F0 drinking saw no SERT genotype differences in males. However, females consumed higher volumes of ethanol compared to males, with SERT −/− females showing the highest intake. A clearer genotype effect was seen in the F1 animals, with reduction in SERT activity leading to enhanced ethanol intake in both sexes. Importantly, paternal exposure to ethanol significantly reduced the ethanol induced motor side effects in offspring, independent of sex and genotype. Conclusions These indicate a difference in the way genetic factors may act across sexes and suggest the involvement of epigenetic mechanisms in the intergenerational effects of alcohol.
 
Article
Rationale Synthetic cannabinoid receptor agonists (SCRAs) are found in illicit smoking products, such as “K2” or “Spice.” Convulsions are commonly reported adverse effects of SCRAs but are poorly understood. Objectives We determined convulsant effects of SCRAs AB-PINACA, and 5F-ADB-PINACA in adult male NIH Swiss mice, and then determined if convulsant effects of AB-PINACA, 5F-AB-PINACA, 5F-ADB-PINACA, and JWH-018 elicited seizure-like effects using EEG. Methods Mice were administered SCRAs or pentylenetetrazole (PTZ) and placed in observation chambers where convulsant effects were scored. The capacity of the CB1R antagonist rimonabant, the benzodiazepine diazepam, or the non-specific CYP450 inhibitor 1-aminobenzotriazole (1-ABT) to attenuate convulsant effects was determined. Other mice were prepared with EEG headmounts to ascertain whether observed convulsions occurred concurrently with seizure-like effects by assessing root-mean-square (RMS) power, high amplitude EEG spike analysis, and videography. Results Mice receiving AB-PINACA or 5F-ADB-PINACA exhibited dose-dependent convulsant effects that were blocked by 10 mg/kg rimonabant pretreatment but not by pretreatment with 10 mg/kg diazepam; these convulsant effects were not altered in the presence of 100 mg/kg 1-ABT. Repeated administration of 10 mg/kg AB-PINACA and 3 mg/kg 5F-ADB-PINACA produced partial tolerance to convulsant effects but did not lead to cross-tolerance to PTZ-induced convulsions. In EEG studies, convulsant doses of AB-PINACA, 5F-AB-PINACA, 5F-ADB-PINACA, and JWH-018 did not produce seizures concomitantly with convulsions. Conclusions These data extend previous findings of convulsant effects of SCRAs and suggest that convulsant effects of AB-PINACA, 5F-AB-PINACA, 5F-ADB-PINACA, and JWH-018 are CB1R-mediated but are not associated with electroencephalographic seizures. These results further suggest that benzodiazepines may not effectively treat convulsions elicited by SCRA use in humans.
 
lOFC inactivation mildly impairs extinction learning. a Location of cannula placements for drug- and vehicle-treated rats in the extinction (left) and control (right) conditions, respectively. The symbols represent the ventral point of the cannula track for each rat and distances are indicated in millimeters from bregma. b Behavioral design for extinction. Behavioral data are represented as mean + SEM percent levels spent freezing during presentations of the target stimulus for c conditioning, d extinction, and e extinction test. Muscimol/baclofen (M/B); vehicle (VEH); extinction-M/B (filled black), n = 12; extinction-VEH (open black), n = 12; control-M/B (filled burgundy), n = 12; and control-VEH (open burgundy), n = 11. Asterisk (*) denotes significant differences
lOFC inactivation abolishes overexpectation following prior extinction training with different cues. a Using the same rats, the location of cannula placements reallocated for drug- and vehicle-treated rats in the overexpectation (left) and control (right) conditions, respectively. The symbols represent the ventral point of the cannula track for each rat and distances are indicated in millimeters from bregma. b Behavioral design for overexpectation. Behavioral data are represented as mean + SEM percent levels of freezing during cue presentations for c conditioning, d overexpectation, and e overexpectation test. Muscimol/baclofen (M/B); vehicle (VEH); overexpectation-M/B (filled black), n = 11; overexpectation-VEH (open black), n = 12; control-M/B (filled burgundy), n = 12; and control-VEH (open burgundy), n = 12. Asterisk (*) denotes significant differences
lOFC inactivation abolishes overexpectation in the absence of prior training. a Location of cannula placements for drug- and vehicle-treated rats in the overexpectation (left) and control (right) conditions. The symbols represent the ventral point of the cannula track for each rat and distances are indicated in millimeters from bregma. b Behavioral design for overexpectation. Behavioral data are represented as mean + SEM percent levels of freezing during cue presentations for c conditioning, d overexpectation, and e overexpectation test. Muscimol/baclofen (M/B); vehicle (VEH); overexpectation-M/B (filled black), n = 12; overexpectation-VEH (open black), n = 12; control-M/B (filled burgundy), n = 12; and control-VEH (open burgundy), n = 12. Asterisk (*) denotes significant differences
lOFC inactivation abolishes overexpectation following prior overexpectation training with different cues. a Using the same rats, the location of cannula placements reallocated for drug- and vehicle-treated rats in the overexpectation (left) and control (right) conditions. The symbols represent the ventral point of the cannula track for each rat and distances are indicated in millimeters from bregma. b Behavioral design for overexpectation. Behavioral data are represented as mean + SEM percent levels of freezing during cue presentations for c conditioning, d overexpectation, and e overexpectation test. Muscimol/baclofen (M/B); vehicle (VEH); overexpectation-M/B (filled black), n = 12; overexpectation-VEH (open black), n = 12; control-M/B (filled burgundy), n = 12; and control-VEH (open burgundy), n = 12. Asterisk (*) denotes significant differences
Article
Rationale and objective Learning to inhibit acquired fear responses is fundamental to adaptive behavior. Two procedures that support such learning are extinction and overexpectation. In extinction, an expected outcome is omitted, whereas in overexpectation two individually trained cues are presented in compound to induce an expectation of a greater outcome than that delivered. Previously, we showed that inactivation of the lateral orbitofrontal cortex (lOFC) in experimentally naïve male rats causes a mild impairment in extinction learning but a profound one in overexpectation. The mild extinction impairment was also transient; that is, it was absent in a cohort of rats that had prior history of inhibitory training (overexpectation, extinction) and their associated controls. This raised the question whether lOFC involvement in overexpectation could likewise be attenuated by prior experience. Methods Using a muscimol/baclofen cocktail, we inactivated the lOFC during overexpectation training in rats with prior associative learning history (extinction, overexpectation, control) and examined its contribution to reducing learned fear. Results Inactivating the lOFC during compound training in overexpectation persistently disrupted fear reduction on test in naïve rats and regardless of prior experience. Additionally, we confirm that silencing the lOFC only resulted in a mild impairment in extinction learning in naïve rats. Conclusion We show that prior associative learning experience did not mitigate the deficit in overexpectation caused by lOFC inactivation. Our findings emphasize the importance of this region for this particular form of fear reduction and broaden our understanding of the conditions in which the lOFC modulates behavioral inhibition.
 
Chronic restraint stress (CRS) induced depression-like models and behavioral test results after ketamine and autophagy inhibitor injection. A Time scheme of experimental procedures. B Grouping of experimental animals and treatments. C Sucrose preference index of SPT after drug injection. D Total travel distance of OFT after drug injection. E Immobility time during the TST following drug injection. CRS, chronic restraint stress; Baf A1, bafilomycin A1. Data were expressed as mean ± s.e.m. (n = 8–12). *P < 0.05, * *P < 0.01, n.s., not significant
The effects of sub-anesthetic doses of ketamine and Baf A1 autophagy. A Autophagy-related markers LC3B (F (3, 56) = 1269, P < 0.0001) and p62 (F (3, 56) = 68.82, P < 0.0001) in the PFC of CRS rates were reduced by ketamine. B Autophagy-related markers LC3B (F (3, 56) = 303, P < 0.0001) and p62 (F (3, 56) = 33.87, P < 0.0001) in the HPC of CRS rats were reduced by ketamine. C Autophagy-related markers LC3B (F (3, 8) = 2626, P < 0.0001) and p62 (F (3, 8) = 127.6, P < 0.0001) in microglia were reduced by ketamine. D NLRP3 (F (3, 28) = 87.95, P < 0.0001) and LC3B (F (3, 28) = 30.95, P < 0.0001) co-location in microglia using immunofluorescence. Blue-DAPI-nucleus; green-LC3-autophagy; red-NLRP3-inflammasome. E Autophagy was increased in the PFC of ketamine-treated CRS rats (F (3, 8) = 39.92, P < 0.001). F Autophagy was increased in the HPC of ketamine-treated CRS rats (F (3, 8) = 41.25, P < 0.001). Data are mean ± s.e.m. *P < 0.05, **P < 0.01, n.s., not significant
The effects of sub-anesthetic doses of ketamine and Baf A1 on NLRP3-related inflammation levels. A Concentration of IL-1β level in serum (F (3, 35) = 8.074, P < 0.001). B Concentration of IL-1β level in CSF (F (3, 20) = 12.04, P = 0.007). C NLRP3 inflammasome-related markers NLRP3 (F (3, 56) = 42.39, P < 0.0001), ASC (F (3, 56) = 29.78, P < 0.0001), caspase1 p10 (F (3, 56) = 58.96, P < 0.0001), and IL-1β (F (3, 56) = 123.9, P < 0.0001) were reduced by ketamine in the PFC of CRS rats. D NLRP3 inflammasome-related markers NLRP3 (F (3, 56) = 154.6, P < 0.0001), ASC (F (3, 56) = 123.8, P < 0.0001), caspase1 p10 (F (3, 56) = 36.45, P < 0.0001), and IL-1β (F (3, 56) = 87.99, P < 0.0001) were reduced by ketamine in the HPC of CRS rats. E NLRP3 and IBA1 co-location in the PFC using immunofluorescence. Blue-DAPI-nucleus; green-NeuN-neuron; red-NLRP3-inflammasome; pink-IBA1-microglia. F NLRP3 and IBA1 co-location in HPC using immunofluorescence. G NLRP3 inflammasome-related markers NLRP3 (F (3, 8) = 649.2, P < 0.0001), ASC (F (3, 8) = 203.3, P < 0.0001), caspase1 p10 (F (3, 8) = 389.1, P < 0.0001), and IL-1β (F (3, 8) = 926.2, P < 0.0001) were reduced by ketamine in microglia. Data are presented as mean ± s.e.m. *P < 0.05, **P < 0.01, n.s., not significant
The effect of sub-anesthetic doses of ketamine and Baf A1 on neuroplasticity-related factors. A Expression of BDNF (F (3, 56) = 197.4, P < 0.001) and synaptophysin (F (3, 56) = 291.9, P < 0.001) was increased by ketamine in the PFC of CRS rats. B Expression of BDNF (F (3, 56) = 258.1, P < 0.001) and Synaptophysin (F (3, 56) = 78.71, P < 0.001) was increased by ketamine with in the HPC of CRS rats. C The Nestin-positive area of IHC staining was increased by ketamine (F (3, 8) = 9.934, P = 0.04). Data are presented as mean ± s.e.m. *P < 0.05, **P < 0.01, n.s., not significant
Article
Background Sub-anesthetic ketamine has rapid-onset effects for the treatment of major depressive disorder (MDD). However, the mechanism underlying ketamine’s antidepressant properties remains unclear. Recent studies have reported an interrelationship between autophagy and the inflammasome, both of which are involved in the pathophysiology of MDD. In this study, we assess whether ketamine exerts its antidepressant effects via an association with the autophagy-NLRP3 inflammasome pathway. Methods We established a depressive-like rat model by treating Wistar Kyoto rats with chronic restraint stress (CRS) for 28 days. Microglial cells from newborn Sprague–Dawley rats were used for in vitro experiments. Results We found sub-anesthetic ketamine treatment reversed depressive-like behavior in CRS rats. Ketamine triggered autophagy in the microglia of prefrontal cortex (PFC) and (hippocampus) HPC, with increased levels of LC3B, decreased levels of p62 protein, and elevated autophagosomes both in vivo and in vitro. Moreover, NLRP3 inflammasome activation was also inhibited by ketamine, with reduced expression of NLRP3-ASC-CASP1 assembly and decreased IL-1β levels in cerebrospinal fluid (CSF) as well as in the serum. Increased BDNF levels and synaptophysin levels were detected in the ketamine-treated group. The rapid anti-depressive effects, elevation of autophagy, reduction in NLRP3, and neuroplasticity-related factors induced by ketamine could be significantly blocked by the autophagy inhibitor Baf A1 (0.1 mg/kg). Conclusions Our findings demonstrate that sub-anesthetic doses of ketamine exert their antidepressant-like effects by inhibiting inflammation and initiating neuroprotection via autophagy activation. These data might help expand future investigations on the antidepressant properties of ketamine.
 
Article
Introduction Methamphetamine (METH, “ice”) is a potent and addictive psychostimulant. Abuse of METH perturbs neurotransmitter systems and induces neurotoxicity; however, the neurobiological mechanisms which underlie addiction to METH are not fully understood, limiting the efficacy of available treatments. Here we investigate METH-induced changes to neuronal nitric oxide synthase (nNOS), parvalbumin and calretinin-expressing GABAergic interneuron populations within the nucleus accumbens (NAc), prefrontal cortex (PFC) and orbitofrontal cortex (OFC). We hypothesise that dysfunction or loss of these GABAergic interneuron populations may disrupt the excitatory/inhibitory balance within the brain. Methods Male Long Evans rats ( N = 32) were trained to lever press for intravenous METH or received yoked saline infusions. Following 14 days of behavioural extinction, animals were given a non-contingent injection of saline or METH (1 mg/kg, IP) to examine drug-primed reinstatement to METH-seeking behaviours. Ninety minutes post-IP injection, animals were culled and brain sections were analysed for Fos, nNOS, parvalbumin and calretinin immunoreactivity in eight distinct subregions of the NAc, PFC and OFC. Results METH exposure differentially affected GABAergic populations, with METH self-administration increasing nNOS immunoreactivity at distinct locations in the prelimbic cortex and decreasing parvalbumin immunoreactivity in the NAc. METH self-administration triggered reduced calretinin immunoreactivity, whilst acute METH administration produced a significant increase in calretinin immunoreactivity. As expected, non-contingent METH-priming treatment increased Fos immunoreactivity in subregions of the NAc and PFC. Conclusion Here we report that METH exposure in this model may alter the function of GABAergic interneurons in more subtle ways, such as alterations in neuronal firing or synaptic connectivity.
 
Article
The amygdala has emerged as the main brain center for the emotional affective dimension of pain and pain modulation. In the amygdala, orexin and cannabinoid receptors are expressed in relatively high concentrations. To investigate the possible interaction between the amygdala orexin and cannabinoid systems on the modulation of inflammatory pain, we conducted formalin, rotarod, and plethysmometer tests, as well as analyzing mRNA expression of orexin and cannabinoid receptors in male rats. The basolateral amygdala (BLA) was unilaterally implanted by a guide cannula. Our results showed that, compared to saline and DMSO/saline, intra-BLA microinjection of orexin-A (50 and 100 µM) decreased flinch response in the early phase, but not in the late phase of the formalin test. However, these injections had no significant effect on the mRNA expression level of BLA, orexin receptor type-1 (Orx1), and cannabinoid receptor type-1 (Cb1). Moreover, intra-BLA administration of Orx1 receptor antagonist (SB-334867; 50 nM) and Cb1 receptor antagonist (AM251; 250 and 500 nM) decreased flinch response only in the early phase of the formalin test as compared to the DMSO group. Although the intra-BLA infusion of orexin-A alone and along with SB-334867 or AM251 decreased flinch response in the early phase of the formalin test, intra-BLA co-microinjection of SB-334867/AM251/OrxA increased flinch response in both early and late phases of the formalin test when compared to the DMSO/OrxA group. Interestingly, in the SB-334867/AM251/OrxA group, the Cb1 receptor was upregulated in all groups in comparison to Orx1 receptors. Our results revealed an interaction between BLA, orexin-A, and Cb1 receptors in inducing anti-nociception in the formalin test.
 
Article
Rationale Synthetic opioids like fentanyl are contributing to the rise in rates of opioid use disorder and drug overdose deaths. Sleep dysfunction and circadian rhythm disruption may worsen during opioid withdrawal and persist during abstinence. Severe and persistent sleep and circadian alterations are putative factors in opioid craving and relapse. However, very little is known about the impact of fentanyl on sleep architecture and sleep–wake cycles, particularly opioid withdrawal. Further, circadian rhythms regulate sleep–wake cycles, and the circadian transcription factor, neuronal PAS domain 2 (NPAS2) is involved in the modulation of sleep architecture and drug reward. Here, we investigate the role of NPAS2 in fentanyl-induced sleep alterations. Objectives To determine the effect of fentanyl administration and withdrawal on sleep architecture, and the role of NPAS2 as a factor in fentanyl-induced sleep changes. Methods Electroencephalography (EEG) and electromyography (EMG) was used to measure non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) at baseline and following acute and chronic fentanyl administration in wild-type and NPAS2-deficient male mice. Results Acute and chronic administration of fentanyl led to increased wake and arousal in both wild-type and NPAS2-deficient mice, an effect that was more pronounced in NPAS2-deficient mice. Chronic fentanyl administration led to decreased NREMS, which persisted during withdrawal, progressively decreasing from day 1 to 4 of withdrawal. The impact of fentanyl on NREMS and arousal was more pronounced in NPAS2-deficient mice. Conclusions Chronic fentanyl disrupts NREMS, leading to a progressive loss of NREMS during subsequent days of withdrawal. Loss of NPAS2 exacerbates the impact of fentanyl on sleep and wake, revealing a potential role for the circadian transcription factor in opioid-induced sleep changes.
 
Mean cost to tracking performance in pixels per 100 ms averaged for 20 words and 20 interstimulus intervals. Significant effects of AH are indicated by *p < .05, #p < .02, ˄p < .01
The effects of hangover and load on a recognition accuracy (%) and b reaction time (msec). Mean (± SEM) number of words correctly recognized during single (- TRACK) and dual-attention (+ TRACK) conditions
Mean (standard error) perceived levels of workload on the 6 dimensions of the NASA-TLX in AH and control (CON) conditions. *p = .02, **p < .01, ****p < .001
Article
Background Alcohol hangover (AH) is associated with impaired attention and memory performance. However, whether this effect is related to reduced attentional resources remains unclear. Aims A dual-attention paradigm was employed to assess the effects of AH on attentional resources, delayed memory recognition, and the interaction between attentional load and AH. Mental effort and perceived performance during AH and control conditions were also assessed. Methods A seminaturalistic, crossover design was used. In total, 25 healthy social drinkers aged 18–35 years, visited the laboratory following a typical night out drinking (Hangover condition) and after alcohol abstinence (control) between 8:30 am and 12:30 pm, with conditions counterbalanced. Attentional load was manipulated via the presence (dual attention) or absence of psychomotor tracking during verbal memory encoding. Perceived mental effort and performance were measured using the NASA-TLX. Participants’ recollected alcohol consumption was used to compute estimated blood alcohol level (eBAC). Results Compared with the control visit, AH was associated with reduced recognition accuracy (particularly more false negatives), higher “tracking costs” (poorer accuracy) in the dual attention condition, increased ratings of “mental demand,” “effort,” and “frustration,” and lower ratings of task performance. There was also a significant main effect of attentional load with poorer recognition accuracy and response time in the dual attention condition. There were no significant interaction effects between hangover and attentional load. Conclusion These findings suggest that reduced attentional resources contribute to the cognitive deficits associated with AH including impaired memory consolidation. They further suggest that while hungover, participants are aware of these deficits but are unable to compensate.
 
Article
Rationale Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and cognitive behaviors. Histamine H3 receptor (H3R) antagonists are considered as therapeutic factors for treating cognitive impairments. Objectives The aim of the present study was to evaluate the effects of the H3R antagonist, ciproxifan (CPX), on cognition impairment especially, spatial learning memory, and synaptic plasticity in the CA1 region of the hippocampus in autistic rats. Methods Pregnant rats were injected with either valproic acid (VPA) (600 mg/kg, i.p.) or saline on an embryonic day 12.5 (E12.5). The effects of the H3R antagonist, ciproxifan (CPX) (1, 3 mg/kg, i.p.), were investigated on learning and memory in VPA-exposed rat pups and saline-exposed rat pups using Morris water maze (MWM) and social interaction tasks. The H2R antagonist, famotidine (FAM) (10, 20, 40 mg/kg, i.p.), was used to determine whether brain histaminergic neurotransmission exerted its procognitive effects through the H2R. In addition, synaptic reinforcement was evaluated by in vivo field potential recording. Results The results showed that VPA-exposed rat pups had significantly lower sociability and social memory performance compared to the saline rats. VPA-exposed rat pups exhibited learning and memory impairments in the MWM task. In addition, VPA caused suppression of long-term potentiation (LTP) in the CA1 area of the hippocampus. Our results demonstrated that CPX 3 mg/kg improved VPA-induced cognitive impairments and FAM 20 mg/kg attenuated cognitive behaviors as well as electrophysiological properties. Conclusions CPX 3 mg/kg improved VPA-induced impairments of LTP as well as learning and memory deficits through H2R.
 
Experimental timelines. a In Experiment 1, after 1 week of acclimation, rats were cannulated in the anterior or posterior PVT. After 1 week of recovery, they underwent conditioned place preference testing: a baseline pretest, three test days involving injection with 0.3 μl of saline vehicle or 0.3 nmol baclofen + 0.03 nmol muscimol, and a posttest. b In Experiment 2, rats were trained for 15 days under a fixed ratio 1 (FR1) schedule for a sucrose reward, then for 3 days under an FR2 schedule, then for 2 days under an FR3 schedule, and they were subsequently cannulated in the posterior PVT. Following 1 week of recovery, they had five more FR3 sessions and were then tested for FR3 responding following injection with saline vehicle or baclofen + muscimol. After that, they underwent extinction training for 8 days and were then tested again following saline vehicle or baclofen + muscimol. c In Experiment 3, rats after 1 week of acclimation were cannulated in the posterior PVT and then given 1 week of recovery or were given 1 week of recovery after conditioned place preference testing (Experiment 1). They were then injected with saline vehicle or baclofen + muscimol and sacrificed 30 min later for analysis using qRT-PCR
Effects of thalamic paraventricular nucleus (PVT) subregion inactivation on conditioned place preference. a Injection locations (indicated by black dots) in the anterior and posterior PVT (n = 5/subregion). Coordinates are relative to Bregma. Adapted from The Rat Brain, 5th edition, G. Paxinos and C. Watson, Copyright 2005, with permission from Elsevier. b Time spent in the baclofen + muscimol–paired chamber was significantly increased after injections in the posterior but not anterior PVT. The conditioned place preference (CPP) score is the difference in seconds between the time spent in the drug-paired chamber during the posttest and the pretest. +p < 0.05 vs. pretest; *p < 0.05 vs. anterior PVT. c Distance traveled during the test was significantly decreased following injections in the PVT. *p < 0.05 vs. acclimation (pretest). d Representative traces of posttest locomotor activity from rats injected in the anterior or posterior PVT. Injection of baclofen + muscimol was paired with the left chamber for this anterior PVT subject and with the right chamber for the posterior PVT subject. Values are mean ± SEM
Effects of posterior thalamic paraventricular nucleus (PVT) inactivation on sucrose seeking behavior. a Injection locations (indicated by black dots) in the posterior PVT (N = 7). Coordinates are relative to Bregma. Adapted from The Rat Brain, 5th edition, G. Paxinos and C. Watson, Copyright 2005, with permission from Elsevier. b Self-administration of sucrose under a fixed ratio 1 schedule of reinforcement. *p < 0.05 vs. session 1. c Self-administration under a fixed ratio 2 schedule of reinforcement. *p < 0.05 vs. session 1. d Self-administration under a fixed ratio 3 schedule of reinforcement. *p < 0.05 vs. session 1. Dotted line indicates the time away from fixed ratio testing due to cannulation and recovery. e Self-administration under a fixed ratio 3 schedule of reinforcement was not significantly altered by injection with baclofen + muscimol into the posterior PVT. f Self-administration during extinction training. *p < 0.05 vs. session 1. g Reinstatement of extinguished sucrose seeking was promoted by injection with baclofen + muscimol into the posterior PVT. *p < 0.05 vs. last extinction and saline vehicle. Values are mean ± SEM
Effects of posterior thalamic paraventricular nucleus (PVT) inactivation on local neuropeptide gene expression. a Injection locations in the posterior PVT (N = 10, n = 5/injection). Red dots indicate locations from “drug-naïve” rats; black dots indicate locations from “drug-experienced” rats from Experiment 1. Coordinates are relative to Bregma. Adapted from The Rat Brain, 5th edition, G. Paxinos and C. Watson, Copyright 2005, with permission from Elsevier. b Example of a fresh brain slice from a rat that had previously received an injection in the PVT. Note that both the tract from the guide cannula and tissue damage from the injector can be seen in this image. c Local injection of baclofen + muscimol significantly reduced gene expression of pituitary adenylate cyclase–activating polypeptide (PACAP) but not enkephalin or neurotensin in the posterior PVT. *p < 0.05 vs. saline vehicle. d Injection of baclofen + muscimol in the posterior PVT did not significantly affect gene expression of PACAP, enkephalin, or neurotensin in the anterior PVT. Values are mean ± SEM
Article
Rationale The experience of reward entails both positive affect and motivation. While the brain regions responsible for these distinct aspects of reward are dissociable from each other, the paraventricular nucleus of the thalamus (PVT) may play a role in both. Objectives To investigate the role of the PVT in both affect and motivation, and to identify neuropeptides that might mediate these effects. Methods Male rats were tested for conditioned place preference following temporary inactivation of the anterior or posterior PVT with local injections of the GABAB and GABAA agonists, baclofen + muscimol. They were tested for sucrose seeking under a fixed ratio 3 (FR3) schedule of reinforcement and after extinction, following injection into the posterior PVT of baclofen + muscimol or saline vehicle. Finally, quantitative real-time PCR was used to examine local neuropeptide gene expression following injection into the posterior PVT of baclofen + muscimol or saline vehicle. Results Conditioned place preference was induced by temporary inactivation of the posterior but not anterior PVT. While sucrose seeking under an FR3 schedule of reinforcement was unaffected by inactivation of the posterior PVT, reinstatement of sucrose seeking was promoted by posterior PVT inactivation. Local gene expression of pituitary adenylate cyclase–activating polypeptide (PACAP), but not enkephalin or neurotensin, was reduced following inactivation of the posterior PVT. Conclusions Temporary inactivation of the posterior PVT affects both affect and motivation as well as local gene expression of PACAP. These results suggest that the posterior PVT is one brain region that may participate in both major aspects of reward.
 
Effect of simvastatin on the State-Trait Anxiety Inventory-State (STAI-s) score. Values are mean differences between visits ± standard error of the mean bars, and an asterisk (*) represents a statistically significant difference between the simvastatin (grey) and placebo (white) groups
Effect of simvastatin on emotional recall (EREC), false alarms. Values are means ± standard errors of the mean bars, and an asterisk (*) represents a statistically significant difference between the simvastatin (grey) and placebo (white) groups
Article
Rationale Clinical studies suggest that the highly lipophilic, anti-inflammatory molecule, simvastatin, might be an ideal candidate for drug repurposing in the treatment of depression. The neuropsychological effects of simvastatin are not known, but their ascertainment would have significant translational value about simvastatin’s influence on mood and cognition. Objectives We aimed to investigate the effects of simvastatin on a battery of psychological tests and inflammatory markers in healthy volunteers. Methods Fifty-three healthy subjects were randomly assigned to 7 days of either simvastatin ( N = 27) or sucrose-based placebo ( N = 26) given in a double-blind fashion. Then, participants were administered questionnaires measuring subjective rates of mood and anxiety, and a battery of tasks assessing emotional processing, reward learning, and verbal memory. Blood samples for C-reactive protein were also collected. Results Compared to placebo, participants on simvastatin showed a higher number of positively valenced intrusions in the emotional recall task ( F 1,51 = 4.99, p = 0.03), but also an increase in anxiety scores ( F 1,51 = 5.37, p = 0.02). An exploratory analysis of the females’ subgroup ( N = 27) showed lower number of misclassifications as sad facial expression in the simvastatin arm ( F 1,25 = 6.60, p = 0.02). No further statistically significant changes could be observed on any of the other outcomes measured. Conclusions We found limited evidence that 7-day simvastatin use in healthy volunteer induces a positive emotional bias while also being associated with an increase in anxiety, potentially reflecting the early effects of antidepressants in clinical practice. Such effect might be more evident in female subjects. Different drug dosages, treatment lengths, and sample selection need consideration in further experimental medicine and clinical studies. Trial registration Clinicaltrials.gov: NCT04652089.
 
Antibiotics affect behavioral responses to METH. a Schematic representation of the experimental procedure. b–c The daily fluid intake and body weight of the four groups over the course of the experiment. d–e 29-day open field activity volume and speed. f Central area distance ratio of the open field. (**p < 0.01, ***p < 0.001; # indicates the comparison between Abx-METH group and METH group, #p < 0.05, ###p < 0.001; mice in each group n = 10)
Effects of METH on the cecum and the gut microbiota of mice with antibiotics treatment. a Gross morphology of the cecum of the four groups of mice with ruler shown for scale. From left to right are saline, METH, Abx-saline, and Abx-METH. b HE staining of mouse intestinal epithelium. c Alteration of the microbial composition following chronic METH exposure and antibiotic treatment (*p < 0.05, **p < 0.01, ***p < 0.001; mice in each group n = 10)
Microbial profiles of mouse cecal contents samples via 16S rRNA gene sequencing. a The analysis of the Venn diagram shows the number of common and unique OTUs in the four groups of samples. b–c The microbial diversity, indicated by the Shannon and Simpson indices, was different between the four groups (***p < 0.001). d LEfSe cladogram represents differentially abundant taxa. Only taxa with LDA scores of more than 2 are presented. e–f In PLS-DA, points of different colors or shapes represent groups of samples under different environments or conditions. g–j Species difference analysis examines the difference in species abundance of the two groups of samples at family level and genus level (mice in each group n = 10; S Saline group, M METH group, AS Abx-Saline group, AM Abx-METH group)
The levels of IL-1β, IL-6, and TNF-α from the NAc, HIp, mPFC, and spleen of mice after antibiotic treatment and METH exposure (*p < 0.05, **p < 0.01, ***p < 0.001; mice in each group n = 8)
SCFA administration impacts the behavior and the gut microbiota of METH exposed mice. a Schematic representation of the experimental procedure. b–c The daily fluid intake and body weight of the four groups over the course of the experiment. d Alteration of the microbial composition. e–f 29-day open field activity volume and speed. g Central area distance ratio of the open field (*p < 0.05, **p < 0.01, ***p < 0.001; # indicates the comparison between SCFA-METH group and METH group, #p < 0.05, ##p < 0.01, ###p < 0.001; mice in each group n = 10)
Article
Rationale and objectives Methamphetamine (METH) is a highly addictive and widely abused drug that causes severe neuroinflammation in the human brain. The gut microbiota has a tremendous impact on the core symptoms of neuropsychiatric disorders via the microbiota-gut-brain (MGB) axis. However, it is not clear whether alterations in the gut microbiota are involved in METH exposure. Methods We established a mouse model with chronic, escalating doses of METH exposure. Intervene in gut microbiota with antibiotics to observe the changes of locomotor activity caused by METH exposure in mice. qPCR and 16S rRNA gene sequencing were used to analyze the gut microbiota profiles. In addition, we tested the levels of inflammatory factors in the nucleus accumbens (NAc), prefrontal cortex (mPFC), hippocampus (HIp), and spleen. Finally, short-chain fatty acids (SCFAs) were supplemented to determine the interaction between behavior changes and the structure of gut microbiota. Results In this research, METH increased the locomotor activity of mice, while antibiotics changed the effect. Antibiotics enhanced the expression of pro-inflammatory cytokines in mPFC, HIp, and spleen of METH-exposed mice. METH altered the gut microbiota of mice after antibiotic treatment, such as Butyricicoccus and Roseburia, which are related to butyrate metabolism. Supplementation with SCFAs changed the behavior of METH-exposed mice and decreased Parabacteroides and increased Lactobacillus in METH-exposed mice gut. Conclusions This research showed that antibiotics affected the behavior of METH-exposed mice and promoted inflammation. Our findings suggest that SCFAs might regulate METH-induced gut microbiota changes and behavior.
 
Article
Background: Neuronal pentraxin-2 (NPTX2, an immediate-early gene), which regulates synapse activity and neuroplasticity, plays an essential role in the neurodevelopmental process. NPTX2 possibly enhances the accumulation of amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptors (AMPAR) on the postsynaptic membranes and stimulates excitatory synaptogenesis. We aimed to evaluate the plasma concentrations of NPTX2 of patients with schizophrenia in acute psychotic episodes compared with matched community-based controls. Methods: Ninety-three (93) patients diagnosed with schizophrenia according to DSM-5 and 83 healthy controls were included. The patients, all of which were in acute psychotic episodes, were recruited from the inpatient clinic. The patients were assessed by the Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression- Severity (CGIS) scale, whereas the healthy subjects were evaluated with Structured Clinical Interview for DSM-5 (SCID-5) to exclude any major psychiatric diagnoses. Results: NPTX2 serum concentrations were significantly higher in the schizophrenia group (p < 0.001). NPTX2 levels negatively correlated with age (p = 0.004) and PANSS-positive symptom scores (p < 0.001). The most determinant factors in predicting the change in NPTX2 levels were PANSS-positive symptom and general psychopathology scores. Conclusions: We conclude that NPTX2 could be involved in schizophrenia pathophysiology and valuable as a synapse-derived and glutamate-related biomarker. Further studies in larger samples assessing NPTX2 levels in remitted schizophrenia patients and combining neuroimaging techniques and cognitive evaluations with blood samples are needed.
 
Article
Rationale and objectives Drug-seeking behavior occurs more readily in some individuals than others. This phenomenon is considered in studies of drug self-administration in which high drug-seeking/taking individuals can be identified. In contrast, studies of conditioned place preference (CPP) often involve a random sample of drug-naïve rodents that includes phenotypes not considered relevant to addiction. The main objective of the current studies was to determine if a priori identification of different conditioning phenotypes could improve the validity and sensitivity of CPP expression as a preclinical test for vulnerability to addiction. Methods and results Analysis of cocaine place conditioning data from 443 Swiss-Webster mice revealed a trimodal distribution with peaks corresponding to means of k = 3 clusters. The cluster means occurred at high, low, or negative preference scores, the latter suggesting a phenotype acquiring conditioned place aversion (CPA). The same clusters were identified in mice conditioned with methamphetamine, MDPV, or amphetamine, and these clusters remained stable and reliable during three additional expression tests spaced at 24 h. A meta-analysis of effect sizes obtained from CPP literature revealed a positively skewed distribution affected by sample size, consistent with the existence of a CPA phenotype within the populations tested. A dopamine receptor antagonist, flupentixol, blocked cocaine CPP expression in a group containing all phenotypes, but sensitivity improved markedly when CPA phenotypes were excluded from the dataset. Conclusions These studies suggest that taking phenotype into consideration when designing place conditioning studies will improve their application as a preclinical tool in addiction biology and drug discovery.
 
Illustration of our experimental tasks based on Bocanegra and Zeelenberg (2009). a Perceptual task: Target Gabor patches whose spatial frequency content varied from trial to trial appeared randomly on the right or left of the fixation point. Participants had to indicate whether they were slightly tilted or strictly vertical. b Emotional task: Facial cues consisting of black and white cropped neutral and fearful faces (male/female) appeared briefly before the target Gabor patches. Instructions remained unchanged. cpd cycles per degree, SF spatial frequency
Raw d′ and quadratic fittings based on group means for the perceptual task. Error bars represent the standard error of the mean
Raw d′ and quadratic fittings based on group means for the emotional task. Error bars represent the standard error of the mean
Article
Rationale Visuo-perceptive deficits in severe alcohol use disorder (SAUD) remain little understood, notably regarding the respective involvement of the two main human visual streams, i.e., magnocellular (MC) and parvocellular (PC) pathways, in these deficits. Besides, in healthy populations, low-level visual perception can adapt depending on the nature of visual cues, among which emotional features, but this MC and PC pathway adaptation to emotional content is unexplored in SAUD. Objectives To assess MC and PC functioning as well as their emotional modulations in SAUD. Methods We used sensitivity indices (d′) and repeated-measures analyses of variance to compare orientation judgments of Gabor patches sampled at various MC- and PC-related spatial frequencies in 35 individuals with SAUD and 38 matched healthy controls. We then explored how emotional content modulated performances by introducing neutral or fearful face cues immediately before the Gabor patches and added the type of cue in the analyses. Results SAUD patients showed a general reduction in sensitivity across all spatial frequencies, indicating impoverished processing of both coarse and fine-scale visual content. However, we observed selective impairments depending on facial cues: individuals with SAUD processed intermediate spatial frequencies less efficiently than healthy controls following neutral faces, whereas group differences emerged for the highest spatial frequencies following fearful faces. Altogether, SAUD was associated with mixed MC and PC deficits that may vary according to emotional content, in line with a flexible but suboptimal use of low-level visual content. Such subtle alterations could have implications for everyday life’s complex visual judgments.
 
Five microstates produced the best fit to the data. Virtually identical microstates were produced for the placebo, low-dose, and high-dose modafinil conditions (see Supplementary Fig. 1)
Microstate occurrence (A), proportion (B), and duration (C). ***p < .001, **p < .01, *p < .05
The observed transition probabilities given the known distribution of microstate labels minus the expected transition probabilities. Positive (green highlighted) values indicate significantly more transitions were made from one microstate to another than would be expected by random chance. Negative (red highlighted) values indicate significantly fewer transitions were made from one microstate to another than would be expected by random chance. Values which have not been highlighted represent observed probabilities that did not significantly differ from expected probabilities
Statistical comparisons of the observed minus expected microstate transitions between placebo, low-dose, and high-doses of modafinil. Positive (green highlighted) values indicate significantly more transitions were made in the first listed treatment condition compared to the second. For example, significantly more A to B transitions were made during the placebo condition compared to the low-dose condition. Negative (red highlighted) values indicate significantly more transitions were made in the second listed treatment condition compared to the first. Values which have not been highlighted represent nonsignificant differences between treatment conditions
Article
Rationale Modafinil has been proposed as a potentially effective clinical treatment for neuropsychiatric disorders characterized by cognitive control deficits. However, the precise effects of modafinil, particularly on brain network functions, are not completely understood. Objectives To address this gap, we examined the effects of modafinil on resting-state brain activity in 30 healthy adults using microstate analysis. Electroencephalographic (EEG) microstates are discrete voltage topographies generated from resting-state network activity. Methods Using a placebo-controlled, within-subjects design, we examined changes to microstate parameters following placebo (0 mg), low (100 mg), and high (200 mg) modafinil doses. We also examined the functional significance of these microstates via associations between microstate parameters and event-related potential indexes of conflict monitoring and automatic error processing (N2 and error-related negativity) and behavioral responses (accuracy and RT) from a subsequent flanker interference task. Results Five microstates emerged following each treatment condition, including four canonical microstates (A–D). Modafinil increased microstate C proportion and occurrence regardless of dose, relative to placebo. Modafinil also decreased microstate A proportion and microstate B proportion and occurrence relative to placebo. These modafinil-related changes in microstate parameters were not associated with similar changes in flanker ERPs or behavior. Finally, modafinil made transitions between microstates A and B less likely and transitions from A and B to C more likely. Conclusions Previous fMRI work has correlated microstates A and B with auditory and visual networks and microstate C with a salience network. Thus, our results suggest modafinil may deactivate large-scale sensory networks in favor of a higher order functional network during resting-state in healthy adults.
 
Article
Rationale The development of substance use disorders involves long-lasting adaptations in specific brain areas that result in an elevated risk of relapse. Some of these adaptations are regulated by the mTOR network, a signalling system that integrates extracellular and intracellular stimuli and modulates several processes related to plasticity. While the role of the mTOR network in cocaine- and alcohol-related disorders is well established, little is known about its participation in opiate use disorders. Objectives To use a heroin self-administration and a withdrawal protocol that induce incubation of heroin-seeking in male rats and study the associated effects on the expression of several genes related to the mTOR system and, in the specific case of Rictor, its respective translated protein and phosphorylation. Results We found that heroin self-administration elicited an increase in the expression of the genes Igf1r , Igf2r , Akt2 and Gsk3a in the basolateral complex of the amygdala, which was not as evident at 30 days of withdrawal. We also found an increase in the expression of Rictor (a protein of the mTOR complex 2) after heroin self-administration compared to the saline group, which was occluded at the 30-day withdrawal period. The activation levels of Rictor, measured by the phosphorylation rate, were also reduced after heroin self-administration, an effect that seemed more apparent in the protracted withdrawal group. Conclusions These results suggest that heroin self-administration under extended access conditions modifies the expression profile of activators and components of the mTOR complexes and show a putative irresponsive mTOR complex 2 after withdrawal from heroin use.
 
Experimental design. Adult Sprague–Dawley rats were exposed to 4 weeks of chronic restraint stress. After the 1st week of stress exposure, the animals of each group were randomly assigned to saline or lurasidone administration for the following 3 weeks. At the end of the 4th week, the animals underwent a 3-week period of washout, during which they were left undisturbed in their cages. At the end of this period, half of the animals from each group were exposed to a 1-h-long acute session of restraint stress, in order to obtain six experimental groups (N = 7–10). All the animals were sacrificed 1 h after the acute stress
Analysis of antioxidant genes Srxn1, Mt1α, Gpx1, and Gpx4 levels in the dorsal hippocampus of rats exposed to acute and chronic stress and treated with lurasidone. The mRNA levels of Srxn1 (a), Mt1α (b), Gpx1 (c), and Gpx4 (d) were analyzed in the dorsal hippocampus of chronically stressed rats, treated with lurasidone and exposed to acute stress after a period of washout. The data, expressed as a percentage of control animals (CTRL, set at 100%), represent the mean ± SEM of at least 7 independent determinations. *P < 0.05; ***P < 0.001 vs. CTRL; ###P < 0.001 vs. CRS; °P < 0,05 vs. CRS/LUR (two-way ANOVA with Fisher’s protected LSD)
Analysis of antioxidant genes Srxn1, Mt1α, Gpx1, and Gpx4 levels in the ventral hippocampus of rats exposed to acute and chronic stress and treated with lurasidone. The mRNA levels of Srxn1 (a), Mt1α (b), Gpx1 (c), and Gpx4 (d) were analyzed in the ventral hippocampus of chronically stressed rats, treated with lurasidone and exposed to acute stress after a period of washout. The data, expressed as a percentage of control animals (CTRL, set at 100%), represent the mean ± SEM of at least 8 independent determinations. *P < 0.05; ***P < 0.001 vs. CTRL; #P < 0.05; ##P < 0.01 vs. CRS; °P < 0.05 vs. CRS/LUR (two-way ANOVA with Fisher’s protected LSD)
Analysis of antioxidant genes Srxn1, Mt1α, Gpx1, and Gpx4 levels in the prefrontal cortex of rats exposed to acute and chronic stress and treated with lurasidone. The mRNA levels of Srxn1 (a), Mt1α (b), Gpx1 (c), and Gpx4 (d) were analyzed in the prefrontal cortex of chronically stressed rats, treated with lurasidone and exposed to acute stress after a period of washout. The data, expressed as a percentage of control animals (CTRL, set at 100%), represent the mean ± SEM of at least 7 independent determinations. **P < 0.01 vs. CTRL; °°P < 0.01 vs. CRS/LUR (two-way ANOVA with Fisher’s protected LSD)
Analysis of the antioxidant z-activation to evaluate the regional antioxidant response after acute and chronic stress and lurasidone treatment. The data of each antioxidant gene were normalized using the Z score method on the respective control groups. Individual Z scores were then averaged to obtain the z-activation for each animal. The data represent the mean ± SEM of at least 7 independent determinations. *P < 0.05 vs. CTRL; °P < 0.05 vs. CRS/LUR (two-way ANOVA with Fisher’s protected LSD)
Article
Rationale Although the occurrence of stressful events is very common during life, their impact may be different depending on the experience severity and duration. Specifically, acute challenges may trigger adaptive responses and even improve the individual’s performance. However, such a physiological positive coping can only take place if the underlying molecular mechanisms are properly functioning. Indeed, if these systems are compromised by genetic factors or previous adverse conditions, the response set in motion by an acute challenge may be maladaptive and even cause the insurgence or the relapse of stress-related psychiatric disorders. Objectives On these bases, we evaluated in the rat brain the role of the antioxidant component of the redox machinery on the acute stress responsiveness and its modulation by potential detrimental or beneficial events. Methods The expression of several antioxidant enzymes was assessed in different brain areas of adult male rats exposed to acute stress 3 weeks after a chronic immobilization paradigm with or without a concomitant treatment with the antipsychotic lurasidone. Results The acute challenge was able to trigger a marked antioxidant response that, despite the washout period, was impaired by the previous adverse experience and restored by lurasidone in an anatomical-specific manner. Conclusions We found that a working antioxidant machinery takes part in acute stress response and may be differentially affected by other experiences. Given the essential role of stress responsiveness in almost every life process, the identification of the underlying mechanisms and their potential pharmacological modulation add further translational value to our data.
 
Article
Rationale Use of psychotropics is relatively prevalent amongst motor vehicle drivers because mobility is also important for persons suffering from psychiatric illness. However, medication side effects may increase the likelihood of being involved in traffic crashes. Objectives This study aimed to assess the association between the use of four types of medication (antipsychotics, benzodiazepines and z-hypnotics, antidepressants and stimulants of ADHD treatment) and the risk of traffic crashes, in general, and single crashes subsequently. Method We conducted a case–control study of data from 130,000 drivers involved in traffic crashes with personal injury and prescription data from all of Denmark during the period 1996–2018. Results For antipsychotics, we found odds ratios of 0.86 and 1.29 for traffic crashes and single crashes, respectively; for benzodiazepines and z-hypnotics, 1.29 and 2.49, respectively; for antidepressants, 1.30 and 2.25, respectively; and for stimulants of ADHD treatment, 1.62 and 1.95, respectively. All p values were below 0.001. Conclusions Based on our results on twofold increased risks of single crashes and moderately increased risks in persons with ADHD, it might seem tempting to ban psychotropic medication in traffic. Conversely, we accept increased risks of traffic crashes in young drivers and in the physically disabled with special aids and, to some extent, with exposure to alcohol. In the end, it is the authorities who must review the evidence and decide whether to prohibit (some types of) psychotropic medication in traffic. Finally, underlying disease and not the drug may increase the risk of being involved in a traffic crash.
 
The group that has used Cannabis in the last 4 weeks took longer to complete the questionnaire and had a greater preponderance of clicks
The significant correlations
Article
Rationale Researchers have traditionally studied the effects of psychoactive drugs such as Cannabis in controlled laboratory settings or relied on retrospective self-reports to measure impairment. However, advances in technology afford opportunities to conduct assessments remotely. Objectives We considered whether objective click-stream data (time and number of clicks spent on a webpage) during an online survey could supplement self-reports of substance use problems. Methods The clickstream data of participants (n = 236) were examined as they completed an online study which included validated psychometric tests (Cannabis Use Disorders Identification Test-Revised, Grit-O, Kessler Psychological Distress Scale, and Brief Self Control Scale). Clickstream data were compared to self-reported Cannabis use. Results People reporting Cannabis use within the last 4 weeks required more time and more clicks to complete the online survey, and this was specifically associated with reported frequency of use, duration of impairment, and problems with memory and concentration. Longer amounts of time and more clicks on the online questionnaire were associated with more recent Cannabis use rather than demographic factors or stimulant use. Conclusions These results imply clickstream data remotely detected indecision or other deficits associated with previous Cannabis use.
 
Allele frequency of rs6296 in healthy control and heroin use disorder groups. Ctrl: healthy control, HUD: heroin use disorder
Dendrogram of interactions among the SNPs in the HTR1B, HTR2A, and HTR3B genes in the context of heroin use disorder
Differentially methylated CpG sites and promoter region of the HTR1B gene between the healthy control and heroin use disorder groups. A Comparison of methylation levels in CpG HTR1B_07 between groups. B Comparison of methylation levels in CpG HTR1B_26 between groups. C Comparison of the mean methylation level in the promoter region of the HTR1B gene between groups. Ctrl, healthy control; HUD, heroin use disorder
Association of rs6296 and methylation levels of the HTR1B gene promoter
Article
Serotonin (5-HT) is implicated in the reward processes underlying substance use disorder. Epigenetic and transcriptional mechanisms contribute to the development of addictive states. To examine the potential mechanisms of 5-HT receptor genes in opioid use disorder, we first determined the associations between several single-nucleotide polymorphism (SNPs) in three representative 5-HT receptor genes (HTR1B, HTR2A, and HTR3B) and susceptibility to heroin use disorder in 1731 participants. Gene–gene interactions among these genes were analyzed. After identifying the susceptibility genes and SNPs for heroin use disorder, DNA methylation in the promoter region of these susceptibility genes was compared between 111 healthy controls and 120 patients with heroin use disorder. In addition, associations between the susceptibility SNPs and methylation of the CpG sites and gene promoters with differential methylation between groups were examined. Finally, the function of the susceptibility SNPs in the expression of the corresponding genes was screened. Our results demonstrated that rs6296 in the HTR1B gene was correlated with susceptibility to heroin use disorder. Gene–gene interactions between the HTR1B and HTR2A genes were identified. The CpG sites HTR1B_07 and HTR1B_26 and the promoter region of the HTR1B gene were hypermethylated in patients with heroin use disorder compared with healthy controls. Notably, rs6296 correlated in an allele-specific manner with methylation in the HTR1B gene promoter in the blood and gene expression of the HTR1B gene in the frontal cortex and hypothalamus. SNP rs6296 was associated with opioid use disorder by involving mechanisms of DNA methylation and expression of the HTR1B gene.
 
Mean accuracy scores for each alcohol treatment condition and perceptual load group, panelled by gorilla noticing (top panel: noticers, N=37, lower panel: non-noticers N = 42). Error bars show 95% confidence intervals
Schematic of trial sequence. Trial 1 is a practice trial and trials 2 and 5 are control trials. On trials 3 and 4, an unexpected stimulus crosses the display across the horizontal midline. Trial 6 is a full attention control trial
Accuracy scores for placebo and alcohol treatment groups, clustered according to whether the participants noticed at least one of the unexpected stimuli. Error bars show 95% confidence intervals
Article
Rationale Inattentional blindness (IB) describes the failure to notice salient but unexpected stimuli in one’s focal visual field. It typically occurs while performing a demanding task (e.g., tracking and counting basketball passes), which consumes attentional resources. Alcohol intoxication is also known to reduce attentional resources, thereby potentially increasing IB and disrupting task performance. Objectives To test the extent to which acute alcohol intoxication and task difficulty disrupt counting performance and increase the rate of IB across two experimental tasks. Methods To test the effects of alcohol consumption and task difficulty on IB we used the Simons and Chabris (1999; 2010) “gorilla in our midst” basketball clip in Experiment 1, and an analogous computerised alternative to the classic “gorilla” task in Experiment 2. Results The rate of IB increased under more demanding (counting) task conditions but was unaffected by alcohol consumption. However, counting performance was impaired by both alcohol and high task difficulty, with the largest detriment being for alcohol participants who noticed the salient but unexpected stimulus. Conclusion The absence of alcohol effects on IB in these experiments was unexpected and warrants further investigation in field vs lab study comparisons, and in combination with baseline cognitive measures to test for alcohol expectancy and task compensation effects.
 
CLZ efficacy and “bottom-up” striatal connectivity. Results of our striatal connectivity analyses are displayed. In A, we display our right dorsal caudate ROI. Increased functional connectivity between this ROI and clusters within B right anterior insula and the right inferior frontal gyrus was observed (P < 0.05, corrected)
CLZ efficacy and “top-down” cortical connectivity. Increased frontoparietal connectivity (A) with the right dorsal caudate (B) was significantly associated with positive symptom reduction across CLZ treatment (P < 0.05, corrected)
CLZ efficacy and R2’. No significant results were observed in analyses comparing change in R2’ versus positive symptom reduction. Results from right dorsal caudate ROIs from our A bottom-up seed ROI and B top-down striatal findings are displayed
Article
Rationale Though numerous studies demonstrate the superiority of clozapine (CLZ) for treatment of persistent psychotic symptoms that are characteristic of treatment-refractory schizophrenia (TRS), what remains unknown are the neural and molecular mechanisms underlying CLZ’s efficacy. Recent work implicates increased corticostriatal functional connectivity as a marker of response to non-CLZ, dopamine (DA) D2-receptor blocking antipsychotic drugs. However, it is undetermined whether this connectivity finding also relates to CLZ’s unique efficacy, or if response to CLZ is associated with changes in striatal DA functioning. Objective In a cohort of 22 individuals with TRS, we examined response to CLZ in relation to the following: (1) change in corticostriatal functional connectivity; and (2) change in a magnetic resonance-based measure of striatal tissue iron (R2’), which demonstrates utility as a proxy measure for elements of DA functioning. Methods Participants underwent scanning while starting CLZ and after 12 weeks of CLZ treatment. We used both cortical and striatal regions of interest to examine changes in corticostriatal interactions and striatal R2’ in relation to CLZ response (% reduction of psychotic symptoms). Results We first found that response to CLZ was associated with an increase in corticostriatal connectivity between the dorsal caudate and regions of the frontoparietal network (P < 0.05, corrected). Secondly, we observed no significant changes in striatal R2’ across CLZ treatment. Conclusion Overall, these results indicate that changes in corticostriatal networks without gross shifts in striatal DA functioning underlies CLZ response. Our results provide novel mechanistic insight into response to CLZ treatment.
 
Modified operant chamber, aerosol delivery system and control equipment
Effect of increasing e-cigarette output wattage setting on total aerosolization volume of 50% propylene glycol/50% vegetable glycerol vehicle. Mean (+ / − SEM) vehicle volume (μl) aerosolized per puff is shown by filled squares. Open circles show volume aerosolized in each of the 5 replicate determinations at each wattage setting
Effect of increasing e-cigarette output wattage during training on number of 4-s nose-only puffs of 50% propylene glycol/50% vegetable glycerol vehicle aerosol received when reinforced by 3 s of access to a 0.01-ml liquid dipper containing sweetened milk. Mean (+ / − SEM) aerosol vehicle vapor puffs per 30-min test session received by male rats are shown in open squares (□) and females are shown in filled circles (●)
Concentration effect curves for fentanyl aerosol puff self-administration (n = 20). The upper panel shows mean (+ / − SEM) 4-s/18-w fentanyl aerosol puffs obtained in the last three 30-min test sessions at each of the fentanyl liquid concentrations (●). Also shown are the mean (+ / − SEM) air-only puffs obtained (□) and mean (+ / − SEM) puffs of fentanyl-free, 50%vegetable glycerol/50% propylene glycol vehicle (○). The lower panel shows mean (+ / − SEM) inactive-lever responses emitted in the last three 30-min test sessions at each fentanyl concentration (●). Also shown are the mean (+ / − SEM) inactive-lever responses emitted in the air puff test condition (□) and mean (+ / − SEM) inactive-lever responses in the fentanyl-free vehicle test condition (○). # indicate statistically significant (p < 0.05) differences compared to air puffs. * indicate statistically significant (p < 0.05) differences compared to drug-free vehicle aerosol. Bracketed NS indicates no statistically significant difference between air puffs and drug-free vehicle aerosol puffs
Concentration effect curves for sufentanil aerosol puff self-administration (n = 18). The upper panel shows mean (+ / − SEM) 4-s/18-w sufentanil aerosol puffs obtained in the last three 30-min test sessions at each of the sufentanil liquid concentrations (●). Also shown are the mean (+ / − SEM) air-only puffs (□) and mean (+ / − SEM) puffs of sufentanil-free vehicle (○). The lower panel shows mean (+ / − SEM) inactive-lever responses emitted in the last three 30-min test sessions at each sufentanil concentration (●). Also shown are the mean (+ / − SEM) inactive-lever responses emitted in the air puff test condition (□) and mean (+ / − SEM) inactive-lever responses in the sufentanil-free, 50% vegetable glycerol/50% propylene glycol vehicle control condition (○). # indicate statistically significant (p < 0.05) differences compared to air puffs. * indicate statistically significant (p < 0.05) differences compared to drug-free vehicle aerosol. Bracketed NS indicates no statistically significant difference between air puffs and drug-free vehicle aerosol puffs
Article
Rationale Rapidly evolving e-cigarette technology developed for self-administering nicotine aerosol has the potential to be utilized to self-administer other aerosolized drugs of abuse. Rodent models which mirror characteristics of human e-cigarette use are necessary to explore the degree to which this may be a public health concern. Objectives Our goal was to develop a highly translational model of discrete nose-only aerosol puff drug delivery to explore the reinforcing effects of fentanyl and sufentanil aerosols in rats. Methods Male and female Sprague–Dawley rats were trained to perform a multiple schedule FR1 lever-press, 4-s (second) nose hold operant during which the subject’s orofacial areas were exposed to drug-free glycerol/propylene glycol aerosol produced by a commercial e-cigarette at a power setting of 18 watts. Each completed 4-s drug-free vehicle aerosol exposure resulted in a 3-s presentation of a 0.1-ml dipper of sweetened milk solution. After training, rats were then allowed to self-administer 4-s nose-only puffs of fentanyl (100–6000 µg/ml) or sufentanil (30–500 µg/ml) aerosol in the absence of paired milk dipper reinforcers. Results All 31 rats learned the lever-press/nose-poke multiple schedule for milk dippers alone and 25 accepted exposure to 4 s of 18 watts of drug-free vehicle aerosol when paired with milk dipper presentations. In the absence of paired milk dipper presentations, fentanyl aerosol puffs at concentrations of 1000 and 3000 µg/ml as well as 100 µg/ml puffs of sufentanil served as reinforcers compared to both air puffs and drug-free vehicle aerosol puffs. There were no significant differences between males and females in number of fentanyl or sufentanil puffs self-administered. Conclusions Discrete nose-only puffs of two potent opioids under exposure conditions comparable to puff durations in human e-cigarette users serve as reinforcers in rats. This outcome suggests that under appropriate conditions e-cigarettes might be a potential alternative delivery mechanism for illicit opioids.
 
Article
Rationale Central aspects of alcohol use disorder (AUD) are the irresistible desire for alcohol and impaired control over its intake. According to the triadic neurocognitive model of addiction, this arises from aberrant functioning of different neural and cognitive systems: an impulsive system, a reflective system, and the abnormal dynamics between both systems based on an insular-dependent system. Objectives In this study, we examined the effects of a single dose of nalmefene on resting-state functional connectivity (rsFC) patterns within and between these addiction-related neural systems in AUD. Methods Non-treatment seeking participants with AUD ( N = 17; 19–66 years, 6 female) took part in a randomized, placebo-controlled, double-blind, crossover study and received either a single dose of 18 mg nalmefene or a placebo. Using seed-based correlation analyses on resting‐state functional magnetic resonance imaging data, we examined the effects of nalmefene on key nodes related to the (1) impulsive system; (2) reflective system; (3) salience network; and (4) default mode network. Results Under nalmefene, participants showed reduced rsFC between components of the impulsive system (Nucleus accumbens–putamen/pallidum/insula). Reduced rsFC was found between elements of the reflective system and impulsive system (orbitofrontal cortex–insula/putamen/pallidum), salience network (orbitofrontal cortex–insula/inferior frontal gyrus), and default mode network (lateral prefrontal cortex–precuneus/cuneus). Components of the salience network showed both increased (anterior cingulate cortex) and decreased (insular cortex) rsFC to elements of the reflective system. Conclusion A single dose of nalmefene impacts rsFC and alters the interaction between key nodes of addiction-related neural systems in non-treatment seeking participants with AUD. Nalmefene may normalize rsFC patterns by weakening the impulsive system while strengthening the reflective system. Trial registration: clinicaltrials.gov: NCT02372318.
 
Mean number of internal and external details generated on the autobiographical interview as a function of condition (Alcohol, n = 61; Placebo, n = 63) and temporal direction (Past; Future). Error bars represent mean standard error
Article
Rationale Acute alcohol consumption adversely affects many cognitive abilities, including episodic memory and executive functioning. However, no study to date has tested whether these acute effects of alcohol also extend to episodic future thinking (EFT). This is a surprising omission given that EFT refers to the ability to imagine oneself experiencing the future, a highly adaptive ability that has been implicated in many important functional behaviours. EFT is also thought to impose demands on episodic memory and executive control. Objectives The current study was designed to provide the first test of whether a moderate dose of alcohol influences EFT and whether any observed EFT difficulties are secondary to broader problems in episodic memory and executive functioning. Sex differences in EFT following acute alcohol consumption were also examined. Methods One hundred and twenty-four healthy adult social drinkers were recruited and randomly assigned to either the alcohol (n = 61) or placebo (n = 63) condition. Participants were administered a dose of 0.6 g/kg alcohol or a matched placebo drink. Results Relative to the placebo condition, EFT was impaired by acute alcohol consumption. This impairment was underpinned by broader difficulties with episodic memory, but not executive functioning. There were no sex differences in EFT performance following acute alcohol use. Conclusion These data provide novel insights into the effects of acute alcohol consumption on EFT and the broader cognitive mechanisms that contribute to these difficulties. The results are discussed in relation to their implications for understanding many of the maladaptive behaviours commonly associated with acute alcohol use.
 
Article
Rationale Neuroinflammation can be alleviated via M2 microglia polarization, which could promote the recovery of perimenopausal depression. Astragalin (AST) possesses anti-neuroinflammatory activity. However, the effects of AST on perimenopausal depression and the molecular mechanism in regulating microglia polarization remained unknown. Objectives The purpose was to investigate the effects of AST on mice with simulated perimenopausal depression through regulating microglia polarization. It was aimed to clarify the molecular mechanism related to the interleukin-4 receptor (IL-4R)/janus kinase (JAK) 1/signal transducer and activator of transcription (STAT) 6 signaling pathway. Methods The ovariectomy (OVX)/chronic unpredictable mild stress (CUMS)-induced murine model of perimenopausal depression was established and treated with AST. Then the depression-like behaviors and cognitive ability of mice were examined. After that, we detected the markers of microglia polarization and its regulatory signals. In addition, lipopolysaccharides (LPS)/adenosine triphosphate (ATP)-induced inflammatory BV2 model were used to verify the potential molecular mechanism. Results AST alleviated perimenopausal depression-like behaviors and memory deficits. AST alleviated microglia activation and increased Ki67-positive cells in dentate gyrus (DG). The viability of BV2 decreased by LPS/ATP was raised by AST. Moreover, both in vivo and in vitro, AST switched microglia from M1 phenotype caused by OVX/CUMS or LPS/ATP to M2 phenotype. The IL-4R/JAK1/STAT6 signaling was restored, and the levels of inducible nitric oxide synthase (iNOS), nuclear NF-KappaB-p65 were reduced by AST. Importantly, AST showed prevention against the ubiquitination modification and degradation of STAT6. Conclusions Our results revealed new insights into molecular mechanism associated with microglia polarization in the effect of AST on the mouse model of perimenopausal depression.
 
Female mice are more sensitive than male mice to the rewarding effects of morphine. (A, B) Time (s) spent in the vehicle (0)- or morphine (1.25 or 2.5 mg/kg)-paired chamber of a conditioned place preference (CPP) apparatus during the pre- or the post-conditioning test and (C) CPP scores by (A) male or (B) female mice. The number of animals for each experimental group is reported within the white bars of panels (A) and (B). Values represent mean ± S.E.M. *P < 0.05, **P < 0.005, ***P < 0.0005 vs. pre-conditioning values or male mice
Morphine disrupts social approach. (A, B) Time (s) spent in the side half-chambers of a three-chamber (3-CH) apparatus containing an unfamiliar same-sex conspecific (Mouse) or a plastic bottle cap (Object) and (C) sociability ratio (%) displayed by vehicle (0)- or morphine (1.25 or 2.5 mg/kg)-treated (A) male or (B) female mice. The number of animals for each experimental group is reported within the bars of panel (C). Values represent mean ± S.E.M. Panels (A) and (B): **P < 0.005, ***P < 0.0005 vs. Object values. #P < 0.05, ##P < 0.005, ###P < 0.0005 vs. Mouse values of the vehicle-treated group. Panel (C): *P < 0.05 vs. vehicle-treated mice, independently of sex
Morphine disrupts motivation for palatable food. (A, B) Active nose-pokes and (C, D) discrimination indices (%) displayed by (A, C) untreated or (B, D) vehicle (0)- or morphine (1.25 or 2.5 mg/kg)-treated male and female mice during the fixed ratio (FR)-1, FR-3, FR-6 and progressive ratio (PR)-2 tests of the palatable food-driven operant behaviour experiment. Treatment (vehicle or morphine) days are depicted in red. Values represent mean ± S.E.M. Panel (A): *P < 0.05 vs. male mice. Panel (B): *P < 0.05, ***P < 0.0005 vs. vehicle (0)- or morphine (1.25 mg/kg)-treated mice, independently of sex
Morphine decreases free-feeding palatable food intake. (A, B) Total food (standard + palatable) intake, calculated as calories ingested per gram of body weight (cal/g of BW), and (C, D) percentage of palatable food (PF) intake displayed by (A, C) untreated or (B, D) vehicle (0)- or morphine (1.25 or 2.5 mg/kg)-treated male and female mice during the free-feeding home-cage experiment. Treatment (vehicle or morphine) days are depicted in red. Values represent mean ± S.E.M. *P < 0.05, **P < 0.005 vs. male mice. ###P < 0.0005 vs. same-sex vehicle-treated mice. †P < 0.05, ‡P < 0.005 vs. same-sex morphine (1.25 mg/kg)-treated mice
Article
Rationale Alongside a pathological, excessive, motivation for substances of abuse, substance use disorder (SUD) patients often show a dramatic loss of interest for naturally rewarding activities, such as positive peer social interaction and food intake. Yet, pre-clinical evidence of the latter SUD features remains scarce and inconsistent. Objectives In the current study, we investigated the effect of non-rewarding and rewarding doses of morphine upon social behaviour, motivation for and intake of palatable food, in male and female C57BL/6J mice. Methods First, the rewarding effects of two relatively low morphine doses (1.25 and 2.5 mg/kg) were assessed using a newly established single substance administration/conditioning trial conditioned place preference (CPP) paradigm. Then, morphine (1.25 and 2.5 mg/kg) effects upon social behaviour, motivation for and intake of palatable food were examined by the three-chamber (3-CH), an operant behaviour and a palatable food preference test, respectively. Results Morphine (2.5 mg/kg) induced CPP in both male and female mice, whereas morphine (1.25 mg/kg) induced CPP only in female mice. Both morphine doses (1.25 and 2.5 mg/kg) reduced sociability, motivation for and intake of palatable food in male and female mice, independently of cognitive function or locomotor activity. Conclusions Female mice were more sensitive than male mice to the rewarding effects of morphine. Moreover, both a non-rewarding and a rewarding dose of morphine impaired the interest for naturally rewarding activities, indicating that brain reward systems might be more sensitive to the deleterious than to the rewarding effects of substances of abuse.
 
Inhibitory control performance in SHR/NCrl and WIS/Crl male rats. For trait impulsivity (DRL 5-s and DRL 30-s testing; panels a–d), values are the mean ± SEM and individual rat data for percentage of reinforced responses (response efficacy) and percentage of responses with inter-response times of less than 2 s (burst responding) averaged over the last 3 daily sessions. For trait compulsivity (SIP testing; panels e, f), values are the mean ± SEM ml/kg water intake for each of the 12 daily sessions or the mean ± SEM and individual rat data for ml/kg water intake averaged over the last 3 daily sessions. *p < 0.004 comparing DRL 5-s response efficacy between SHR/NCrl and WIS/CRL; **p < 0.003 comparing DRL 5-s burst responding between SHR/NCrl and WIS/Crl; ***p < 0.00002 comparing DRL 30-s response efficiency between SHR/NCrl and WIS/Crl; ****p < 0.00007 comparing DRL 30-s burst responding between SHR/NCrl and WIS/Cr; ^p < 0.04 comparing ml/kg water intake between SHR/NCrl and WIS/Crl on sessions 4–12; and ^^p < 0.0003 comparing ml/kg water intake between SHR/NCrl and WIS/Crl on the last 3 daily sessions
Baseline drug self-administration performance in SHR/NCrl and WIS/Crl male rats under the FR1 drug-taking schedule and the FR1, RI 120-s; FR1, 600-s TO tandem schedule. Values are the mean ± SEM and individual rat data for the number of responses on the taking lever (panel a), number of responses on the seeking lever (panel b), and number of seek-take cycles completed (panel c), averaged over the last 3 daily sessions. In panel a, *p < 0.001 comparing SHR/NCrl cocaine to WIS/Crl cocaine; **p < 0.009 comparing SHR/NCrl yoked-saline to WIS/Crl yoked-saline; ^p < 0.008 comparing cocaine to yoked-saline overall; and ^^p < 0.003 comparing heroin + cocaine to yoked-saline overall. In panel b, *p < 0.002 comparing SHR/NCrl to WIS/Crl across cocaine, heroin + cocaine, and yoked-saline drug groups overall; ^p < 0.002 comparing cocaine to yoked-saline overall; and ^^p < 0.005 comparing heroin + cocaine to yoked-saline overall. In panel c, *p < 0.001 comparing SHR/NCrl cocaine to WIS/Crl cocaine
Punished drug self-administration performance in SHR/NCrl and WIS/Crl male rats under the FR1, RI 120-s; FR1, 600-s TO tandem schedule. Values are the mean ± SEM number of responses on the seeking lever (panel a), number of seek-take cycles completed (panel b), and number of foot shocks received (panel c) across the 8 daily sessions. In panel a, *p < 0.047 comparing SHR/NCrl cocaine to WIS/Crl cocaine on session 1; *p < 0.005 comparing SHR/NCrl yoked-saline to WIS/Crl yoked-saline overall; ^p < 0.001 comparing session 1 to sessions 2–8 in SHR/NCrl self-administering cocaine and heroin + cocaine and in WIS/Crl self-administering heroin + cocaine; and #p < 0.002 comparing heroin + cocaine to cocaine in WIS/Crl. In panel b, *p < 0.005 comparing SHR/NCrl cocaine to WIS/Crl cocaine on session 1; ^p < 0.001 comparing session 1 to sessions 2–8 overall. In panel c, *p < 0.001 comparing SHR/NCrl to WIS/Crl on session 1 overall; and ^p < 0.001 comparing session 1 to sessions 2–8 overall
Operant avoidance performance in SHR/NCrl and WIS/Crl male rats. Values are the mean ± SEM for percent avoidance accuracy (panel a) and number of escape foot shocks received (panel b) across the 5 daily sessions. In panel a, *p < 0.001 comparing SHR/NCrl yoked-saline to WIS/Crl yoked-saline overall; ^p < 0.001 comparing session 1 to sessions 2–5 and comparing session 2 to sessions 3–5 overall; and #p < 0.009 and p < 0.001 comparing SHR/Crl cocaine and heroin + cocaine, respectively, to SHR/NCrl yoked-saline overall. In panel b, *p < 0.002 comparing SHR/NCrl yoked-saline to WIS/Crl yoked-saline overall; ^p < 0.001 comparing session 1 to sessions 2–5 and comparing session 2 to sessions 3–5 overall; and #p < 0.022 and p < 0.001 comparing SHR/Crl cocaine and heroin + cocaine, respectively, to SHR/NCrl yoked-saline overall
Proposed pathways for predicting compulsive drug use are based on correlation analyses of selected dependent measures in SHR/NCrl and WIS/Crl receiving cocaine and yoked-saline (panel a) and heroin + cocaine and yoked-saline (panel b). Illustrated are correlations between pre-drug history measures (trait impulsivity and trait compulsivity), prolonged drug use history measures (baseline FR1 drug taking and baseline FR1, RI 120-s; FR1, 600-s TO drug seeking), and post-drug history measures (punished seek-take cycles on session 1 and avoidance accuracy in the operant avoidance task)
Article
Rationale The nature and predictors of insensitivity to aversive consequences of heroin + cocaine polysubstance use are not well characterized. Objectives Translational methods incorporating a tightly controlled animal model of drug self-administration and measures of inhibitory control and avoidance behavior might be helpful for clarifying this issue. Methods The key approach for distinguishing potential contributions of pre-existing inhibitory control deficits vs. drug use history in meditating insensitivity to aversive consequences was comparison of two rat strains: Wistar (WIS/Crl), an outbred strain, and the spontaneously hypertensive rat (SHR/NCrl), an inbred strain shown previously to exhibit heightened cocaine and heroin self-administration and poor inhibitory control relative to WIS/Crl. Results In separate tasks, SHR/NCrl displayed greater impulsive action and compulsive-like behavior than WIS/Crl prior to drug exposure. Under two different schedules of drug delivery, SHR/NCrl self-administered more cocaine than WIS/Crl, but self-administered a similar amount of heroin + cocaine as WIS/Crl. When half the session cycles were punished by random foot shock, SHR/NCrl initially were less sensitive to punishment than WIS/Crl when self-administering cocaine, but were similarly insensitive to punishment when self-administering heroin + cocaine. Based on correlation analyses, only trait impulsivity predicted avoidance capacity in rats self-administering cocaine and receiving yoked-saline. In contrast, only amount of drug use predicted avoidance capacity in rats self-administering heroin + cocaine. Additionally, baseline drug seeking and taking predicted punishment insensitivity in rats self-administering cocaine or heroin + cocaine. Conclusions Based on the findings revealed in this animal model, human laboratory research concerning the nature and predictors of insensitivity to aversive consequences in heroin and cocaine polysubstance vs. monosubstance users is warranted.
 
Task structure (a) and experimental groups (b). a Example timeline of task with days and phases labeled. Counterbalancing for order of Sal-LiCl injections was employed. Mediated test (MT) involves two-bottle choice between O1 and O2; direct test (DT) involves two-bottle choice between F1 and F2. b Three experimental conditions represented with drugs administered each day of the devaluation phase shown in subsequent columns. W: water, A: associative day, D: devaluation day, MT: mediated test, DT: direct test, F1: flavor 1, F2: flavor 2, O1: odor 1, O2: odor 2, Sal: saline, LiCl: lithium chloride
Devaluation phase performance. a Timeline of events during each devaluation phase training day and when each drug was administered. b Mean + / − SEM shown for consumption during 1 h of access, across 3 days of each type of training (saline or LiCl injection after flavor consumption) for three drug conditions: 0 mg/kg (n = 27), 10 mg/kg (n = 26), and 30 mg/kg (n = 27) ketamine. Significant effect was observed for day (p = 0.028), day type (p < 0.001), and interactions between day*aversion type (p < 0.001) as well as ketamine-30 mg/kg*day*aversion type (p = 0.022)
Performance during testing. a Schematic of the relationship between direct and mediated learning. b Graph depicts mean + / − SEM for the Avoidance Index (neutral/total consumed) with individual point representing each individual rat’s performance across drug conditions: saline (n = 27), ketamine-moderate (n = 26), and ketamine-high (n = 27). Significant effect of the 10-mg/kg dose of ketamine was found for mediated learning (p = 0.040), but not the higher dose, while a significant effect of only the 30-mg/kg dose of ketamine was found for direct learning (p < 0.001)
Article
Rationale While neural correlates of hallucinations are known, the mechanisms have remained elusive. Mechanistic insight is more practicable in animal models, in which causal relationships can be established. Recent work developing animal models of hallucination susceptibility has focused on the genesis of perceptual expectations and perceptual decision-making. Both processes are encompassed within mediated learning, which involves inducing a strong perceptual expectation via associative learning, retrieving that memory representation, and deciding whether this internally generated percept is predictive of an external outcome. Mediated learning in rodents is sensitive to many psychotomimetic manipulations. However, we do not know if these manipulations selectively alter learning of perceptual expectations versus their retrieval because of their presence throughout all task phases. Objectives Here, we used mediated learning to study the targeted effect of a psychotomimetic agent on the retrieval of perceptual expectation. Methods We administered (R,S)-ketamine to rats selectively during the devaluation phase of a mediated learning task, when the representation of the expected cue is retrieved, to test the hypothesis that internally generated perceptual experiences underlie this altered mediated learning. Results We found that ketamine increased only mediated learning at a moderate dose in rats, but impaired direct learning at the high dose. Conclusions These results suggest that ketamine can augment retrieval of perceptual expectations and thus this may be how it induces hallucination-like experiences in humans. More broadly, mediated learning may unite the conditioning, perceptual decision-making, and even reality monitoring accounts of psychosis in a manner that translates across species.
 
Chemical structure of CBD and potential targets for its therapeutic effect on ASD. CBD acts as an agonist of the receptors TRPV1, PPARγ, and 5-HT1A and as an antagonist of the receptor GPR55. CBD acts as an inverse agonist of the D2 and D3 receptors. CBD is suggested to act as an inverse agonist and a negative allosteric modulator of CB1 and CB2 receptors. CBD inhibits the enzyme FAAH, with a consequent increase in anandamide (AEA) levels. This endocannabinoid ligand can activate CB1, CB2, and TRPV1 receptors. CBD increases the activity of mitochondrial complexes and displays antioxidant and anti-inflammatory effects that are partially mediated by its actions on TRPV1, mitochondria, and PPARγ. CBD inhibits the balanced nucleoside transporter (ENT1) responsible for synaptic adenosine uptake, increasing extracellular adenosine levels. CBD can directly or indirectly activate Gly receptors. CBD is also capable of inhibiting sodium channels. TRPV1, transient receptor potential vanilloid type 1; PPARγ, peroxisome proliferator-activated receptor gamma; 5-HT1A, serotonin receptor 1A; GPR55, G-protein-coupled receptor 55; D2, dopaminergic receptor type 2; D3, dopaminergic receptor type 3; CB1, cannabinoid receptor type 1; CB2, cannabinoid receptor type 2; FAAH, fatty acid amide hydrolase; A1, adenosine type 1 receptor; Gly, glycine receptors
The following image suggests the therapeutic profile of CBD in treating the core symptoms of ASD, such as improving social interaction and communication, and decreasing stereotyped behaviors, in addition to its neuroprotective profile. CBD may also have therapeutic effects on ASD-associated comorbidities such as psychosis, aggression, epilepsy, conditions related to anxiety and depression, and obsessive–compulsive disorder (OCD). CBD may offer a promising treatment for the range of symptoms of ASD. However, due to the complexity of ASD, it is still a challenge to select patients who would benefit from the therapeutic effects of CBD and individuals who are more prone to side effects
Article
Rationale Autism spectrum disorder (ASD) is defined as a group of neurodevelopmental disorders whose symptoms include impaired communication and social interaction, restricted and repetitive patterns of behavior, and varying levels of intellectual disability. ASD is observed in early childhood and is one of the most severe chronic childhood disorders in prevalence, morbidity, and impact on society. It is usually accompanied by attention deficit hyperactivity disorder, anxiety, depression, sleep disorders, and epilepsy. The treatment of ASD has low efficacy, possibly because it has a heterogeneous nature, and its neurobiological basis is not clearly understood. Drugs such as risperidone and aripiprazole are the only two drugs available that are recognized by the Food and Drug Administration, primarily for treating the behavioral symptoms of this disorder. These drugs have limited efficacy and a high potential for inducing undesirable effects, compromising treatment adherence. Therefore, there is great interest in exploring the endocannabinoid system, which modulates the activity of other neurotransmitters, has actions in social behavior and seems to be altered in patients with ASD. Thus, cannabidiol (CBD) emerges as a possible strategy for treating ASD symptoms since it has relevant pharmacological actions on the endocannabinoid system and shows promising results in studies related to disorders in the central nervous system. Objectives Review the preclinical and clinical data supporting CBD’s potential as a treatment for the symptoms and comorbidities associated with ASD, as well as discuss and provide information with the purpose of not trivializing the use of this drug.
 
Violin plots and box plots of salivary (a) estradiol and (b) progesterone levels by menstrual group (menstrual phase = 21, follicular phase = 19, luteal phase = 16)
Estimated marginal means of alpha1 power by drug condition and caffeine consumption questionnaire (CCQ) score (n = 56); note that “Low CCQ” and “High CCQ” represent scores one standard deviation below or above the sample mean, respectively. Error bars represent standard error of the mean (SEM)
Scatterplot of the correlation between alpha1 power difference score (Caffeine-Placebo) and caffeine consumption questionnaire (CCQ) score (n = 56)
Alpha2 power by region, hemisphere, and menstrual group, controlling for caffeine consumption questionnaire (CCQ) score (menstrual phase = 21, follicular phase = 19, luteal phase = 16); error bars represent standard error of the mean (SEM)
Article
Rationale Caffeine is the most consumed stimulant worldwide, and there is great interest in understanding its neurophysiological effects. Resting-state electroencephalography (EEG) studies suggest that caffeine enhances arousal, which suppresses the spectral power of alpha frequencies associated with reduced alertness. However, it is unclear whether caffeine’s neurophysiological effects vary across the human menstrual cycle. Objective The objective of our study was to test whether caffeine’s effect on EEG activity differs across the human menstrual cycle. Methods Fifty-six female participants were randomly assigned to complete the experiment while in either their menstrual (n = 21), follicular (n = 19), or luteal (n = 16) phase. Each participant completed two study sessions in the same menstrual phase, approximately 1 month apart, during which they were administered either a caffeine pill (200 mg, oral) or a placebo pill in a counterbalanced order using a randomized double-blinded procedure. We measured their eyes-closed resting-state EEG approximately 30 min after pill administration and conducted a spectral power analysis at different frequency bands. Results Caffeine reduced EEG power in the alpha1 frequency band (8–10 Hz), but only for participants who self-reported higher weekly caffeine consumption. Importantly, caffeine’s effects did not differ by menstrual phase. Conclusions We conclude that when studying caffeine’s effects on resting-state EEG, participants’ baseline caffeine consumption is more influential than their menstrual cycle phase. This study has important implications for the inclusion of menstruating individuals in neurophysiological studies of caffeine.
 
Article
Rationale Second-generation antipsychotic (SGA) medications can produce abnormal weight gain and metabolic dysfunction in children, but little is known about the post-treatment consequences of adolescent SGA exposure. Objectives The objective of this study was to determine the long-term, post-treatment effects of adolescent olanzapine exposure on weight and metabolic function and whether dietary fish oil (FO) modulated any observed effects of olanzapine. Methods Male and female mice were fed a high-fat, high-sugar (HF-HS) diet or an HF-HS diet supplemented with fish oil (HF-HS-FO) and were treated with olanzapine or vehicle for 29 days beginning on postnatal day 37. Results In male mice, adolescent olanzapine treatment suppressed weight gain during and after treatment and improved metabolic function in adulthood; dietary fish oil reduced weight gain, increased expression of fatty acid oxidation genes, and decreased expression of genes associated with fatty acid synthesis and inflammation. In contrast, few effects were observed in female mice. Conclusions The current results suggest that adolescent olanzapine exposure can produce long-term alterations in weight and metabolic function in male mice and that dietary fish oil can reduce adverse effects of lifelong consumption of an HF-HS diet. Because expected adverse effects of adolescent olanzapine treatment were not observed, the potential beneficial effects of dietary fish oil for SGA-induced weight gain and metabolic dysfunction could not be evaluated.
 
Article
Rationale It is known that both selective serotonin and serotonin noradrenaline reuptake inhibitors (SSRI, SNRI) are first-line drugs for the treatment of major depressive disorder. It has also been considered that both SSRI and SNRI can improve the symptoms of major depressive disorder by increasing the concentration of monoamine in the synaptic cleft based on the monoamine hypothesis. However, accumulating evidence has indicated that inflammation in the brain may be a key factor in the pathophysiological mechanisms that underlie the development of major depressive disorder. Objectives It has been advocated that microglial cells may regulate the inflammatory response under pathological conditions such as major depressive disorder. In this study, we focused on whether duloxetine can ameliorate the inflammatory response induced by lipopolysaccharide (LPS) in BV-2 microglial cells. Results Our results indicated that duloxetine significantly decreased the NO production induced by LPS. The increase in the protein expression level of iNOS induced by LPS was significantly decreased by treatment with duloxetine. Moreover, the increases in the protein expression levels of phosphorylated-IκBα, phosphorylated-Akt and Akt induced by LPS were also significantly decreased. Unexpectedly, the protein expression levels of other pro-inflammatory factors such as COX-2 and the phosphorylation ratios for various molecules including IκBα and Akt were not changed by treatment with duloxetine. Conclusions These findings suggest that duloxetine may have an anti-inflammatory effect, which could contribute to its therapeutic effectiveness for major depressive disorder.
 
Changes in miR-222-3p expression in the NAc of METH-induced CPP mice. a The CPP paradigm and dosing schedule. b METH-induced CPP, n = 7. * P < 0.05 versus the saline group. c Locomotor activity of each group, n = 7. d miR-222-3p expression in the NAc, n = 6. * P < 0.05 versus the saline group
Effects of miR-222-3p on METH-induced CPP. a AAV microinjection and drug treatment schedule. b, c AAV-mediated overexpression (b) and knockdown (c) of miR-222-3p in the NAc of mice, n = 6. * P < 0.05 versus control groups. d, f Effects of overexpression (d) and knockdown (f) of miR-222-3p in the NAc on METH-induced CPP in mice, n = 7 (d), n = 8 (f). * P < 0.05 versus the AAV-control + METH group; # P < 0.05 versus the AAV-anti-miR-222-3p + METH group. e, g Effects of overexpression (e) and knockdown (g) of miR-222-3p in the NAc on locomotor activity in mice, n = 7 (e), n = 8 (g)
Prediction of target genes of miR-222-3p and functional analysis. a Venn diagram shows the predicted genes that overlapped between the TargetScan database and miRDB database. b, c GO analysis (biological process, b) and KEGG pathways of predicted targets (c), which are presented as -log10 (P-value)
miR-222-3p modulation of Ppp3r1, Cdkn1c, Fmr1, and PPARGC1A mRNA expression in response to METH-induced CPP, n = 5–6. * P < 0.05 versus the AAV-control-1 + saline group; # P < 0.05 versus the AAV-control-1 + METH group
Article
Rationale MicroRNA (miRNA) control of post-transcription gene expression in the nucleus accumbens (NAc) has been implicated in methamphetamine (METH) dependence. Conditioned place preference (CPP) is a classical animal procedure that reflects the rewarding effects of addictive drugs. miR-222-3p has been reported to play a key role in various neurological diseases and is strongly associated with alcohol dependence. Nevertheless, the role of miR-222-3p in METH dependence remains unclear. Objective To explore the molecular mechanisms underlying the role of miR-222-3p in the NAc in METH-induced CPP. Methods miR-222-3p expression in the NAc of METH-induced CPP mice was detected by quantitative real-time (qPCR). Following adeno-associated virus (AAV)-mediated overexpression or knockdown of miR-222-3p in the NAc, mice were subjected to CPP to investigate the effects of miR-222-3p on METH-induced CPP. Target genes of mir-222-3p were predicted using bioinformatics analysis. Candidate target genes for METH-induced CPP were validated by qPCR. Results miR-222-3p expression in the NAc was decreased in CPP mice. Overexpression of miR-222-3p in the NAc blunted METH-induced CPP. Ppp3r1, Cdkn1c, Fmr1, and PPARGC1A were identified as target gene transcripts potentially mediating the effects of miR-222-3p on METH-induced CPP. Conclusion Our results highlight miR-222-3p as a key epigenetic regulator in METH-induced CPP and suggest a potential role for miR-222-3p in the regulation of METH-induced reward-related changes in the brain.
 
DS task training prior to vapor exposure. A Timeline of experiments. Rats first underwent home cage intermittent access to alcohol and training in the DS task, prior to ethanol vapor exposure. Circles indicate the number of weeks in each experimental phase. B Ethanol consumption (g/kg) during home cage intermittent access, prior to task training, C Cumulative distribution of mean ethanol consumption during the final 2 weeks of intermittent access in males (red) versus females (blue). The dotted line marks the minimum consumption required during this period to move on to training in the DS task. D Ethanol consumption during training in the DS task. E Port entry probability during the DS ethanol cue (solid line) and NS control cue (dotted line) across training. F Final port entry probability during the DS (left) and NS (right) in rats assigned to vapor exposure (CIE) or control conditions after training. G Ethanol consumption during the final DS task training session. Lines with shading and bar plots with error bars indicated mean + / − SEM. Circles represent data from individual animals
Cue responses and ethanol consumption in the DS task after vapor exposure. A Timeline of experiments. Following home cage ethanol exposure, cue training, and ethanol vapor exposure, rats underwent cue testing. Circles indicate the number of weeks in each experimental phase. B Port entry probability during the DS (left) or NS (right) in the cue probe test (no ethanol delivered) after being exposed to vapor (CIE) or control conditions. Rats are split into those that did not receive alcohol access during acute withdrawal in the vapor phase (top) or rats that did receive access in acute withdrawal (bottom). Circles represent data from individual animals. Bar plots with error bars indicated mean + / − SEM. C Ethanol consumption during cue “retraining” and testing in which ethanol was reintroduced and the number of trials was increased across sessions, in rats that received vapor exposure (CIE) or control conditions after task training. Lines with shading indicate mean + / − SEM. D Ethanol consumption during cue testing, in which the amount of 15% ethanol delivered on each trial was increased from 0.1 to 0.2 mL. E Port entry probability during the DS (solid lines) or NS (dotted lines) during cue “retraining” and testing in which ethanol was reintroduced and the number of trials was increased across sessions. F Port entry probability during the DS and NS during cue testing in which the amount of 15% ethanol delivered on each trial was increased from 0.1 to 0.2 mL
DS task training after vapor exposure. A Timeline of experiments. Rats first underwent home cage intermittent access to alcohol and ethanol vapor exposure prior to training in the DS task and subsequent cue testing. Circles indicate the number of weeks in each experimental phase. B Port entry probability during the DS (solid lines) or NS (dotted lines) during DS task training after exposure to ethanol vapor (CIE) or control conditions. Lines with shading indicate mean + / − SEM. C Ethanol consumption (g/kg) during DS task training after CIE or control conditions. D Total port entries during DS task training after CIE or control conditions. E Port entry probability during the DS (left) or NS (right) in the cue probe test (no ethanol delivered) that occurred after DS task training. Bar plots with error bars indicate mean + / − SEM. Circles represent data from individual animals. F Ethanol consumption during cue “retraining” and testing in which ethanol was reintroduced and the number of trials was increased across sessions, in rats that received vapor exposure (CIE) or control conditions prior to task training. Lines with shading indicate mean + / − SEM. G Ethanol consumption during cue testing in which the amount of 15% ethanol delivered on each trial was increased from 0.1 to 0.2 ml. H Port entry probability during the DS (solid lines) or NS (dotted lines) during cue “retraining” and testing in which ethanol was reintroduced, and the number of trials was increased across sessions. I Port entry probability during the DS and NS during cue testing in which the amount of 15% ethanol delivered on each trial was increased from 0.1 to 0.2 mL. Lines with shading and bar plots with error bars indicate mean + / − SEM
Blood ethanol levels and ethanol consumption during the vapor exposure phase. A Blood ethanol concentrations (BECs) was measured after the first vapor exposure of the week (Tuesday mornings) across 3 weeks of vapor exposure. B Ethanol consumption (g/kg) during the twice weekly ethanol consumption tests 6–8 h after CIE rats were removed from the vapor chambers. Rats on the left received vapor exposure (CIE) or control conditions after DS task training. Lines with shading and bar plots with error bars indicated mean + / − SEM. Circles represent data from individual animals
Quinine-adulterated alcohol consumption. Bar graphs show the % change in consumption from ethanol alone at 10, 30, and 90 mg/L quinine after exposure to ethanol vapor (CIE) or control conditions (A) and after subsequent DS task training (B). Bar plots with error bars indicated mean + / − SEM. Circles represent data from individual animals. * = p < 0.05 interaction between CIE vapor inhalation and sex
Article
Rationale Chronic intermittent ethanol (CIE) vapor inhalation is a widely used model of alcohol dependence, but the impact of CIE on cue-elicited alcohol seeking is poorly understood. Objective Here, we assessed the effects of CIE on alcohol-seeking elicited by cues paired with alcohol before or after CIE vapor inhalation. Methods In experiment 1, male and female Long-Evans rats were trained in a discriminative stimulus (DS) task, in which one auditory cue (the DS) predicts the availability of 15% ethanol and a control cue (the NS) predicts no ethanol. Rats then underwent CIE or served as controls. Subsets of each group received access to oral ethanol twice a week during acute withdrawal. After CIE, rats were presented with the DS and NS cues under extinction and retraining conditions to determine whether they would alter their responses to these cues. In experiment 2, rats underwent CIE prior to training in the DS task. Results CIE enhanced behavioral responses to cues previously paired with alcohol, but only in rats that received access to alcohol during acute withdrawal. When CIE occurred before task training, male rats were slower to develop cue responses and less likely to enter the alcohol port, even though they had received alcohol during acute withdrawal. Conclusions These results suggest that CIE vapor inhalation alone does not potentiate the motivational value of alcohol cues but that an increase in cue responses requires alcohol experience during acute withdrawal. Furthermore, under some conditions, CIE may disrupt responses to alcohol-paired cues.
 
Top-cited authors
Pierre Simon
  • Centre Hospitalier Yves Le Foll Hospital
Bernard Thierry
  • CNRS INRAE University of Tours
James MacKillop
  • McMaster University
Harriet de Wit
  • University of Chicago
Trevor W Robbins
  • University of Cambridge