Psychopharmacology

Following cocaine self-administration, male and female rats received daily semaglutide during a 30-day abstinence period before cue- and cocaine-induced reinstatement tests. Semaglutide attenuated cue-induced reinstatement and cocaine-induced stereotypy, although operant responding was elevated following cocaine priming. These findings support further investigation of semaglutide as a treatment for cocaine use disorder.

Background The head-twitch response (HTR) is a serotonin2A receptor (5-HT2AR) dependent behavioral correlate of serotonergic psychedelic action in rodent models. Although cortical 5-HT2ARs have been implicated in HTRs, the contribution of specific cortical circuits to this behavior remains poorly defined, with a few reports implicating the medial prefrontal cortex (mPFC) in the generation of HTRs. Results The serotonergic psychedelic, 2,5-dimethoxy-4-iodoamphetamine (DOI), induced head-twitch responses (HTRs) in male and female rats and mice, with sex differences noted only in mice. DOI also increased ear-scratch responses (ESRs), and reduced digging and grooming behaviors only in mice. While the DOI-evoked HTRs and ESRs were absent in 5-HT2AR knock-out (5-HT2AR KO) mice, reduced digging and grooming occurred in both wild-type and 5-HT2AR KO mice. We assessed the role of 5-HT2ARs in the mPFC in regulating DOI-induced HTRs using pharmacological and genetic approaches. Targeted DOI microinfusion into the mPFC did not induce HTRs in rats, in contrast to the robust increase in HTRs noted following systemic DOI administration. Local delivery of the selective 5-HT2AR antagonist, MDL100907, into the mPFC also had no effect on the systemic DOI-evoked increase in HTRs in rats. Experiments capitalizing on genetic strategies to perturb 5-HT2AR expression in the mPFC, indicated that viral restoration of 5-HT2AR expression in mPFC CaMKII-positive excitatory neurons was not sufficient to reinstate DOI-evoked HTRs or ESRs in 5-HT2AR KO mice. Further, conditional 5-HT2AR deletion in CaMKII-positive excitatory neurons in the mPFC did not alter systemic DOI-induced HTRs and ESRs in mice. Conclusions These findings indicate that the serotonergic psychedelic DOI induces species- and sex-specific behavioral effects in rodent models, with a robust 5-HT2AR dependence noted for DOI-evoked HTRs and ESRs. Further, we show that 5-HT2ARs in the mPFC do not appear to contribute to the enhanced HTRs and ESRs elicited by DOI.

Background and Purpose High novelty-seeking is an endophenotype associated with greater vulnerability to drug addiction, marked by a hyperdopaminergic state and reduced dopamine D2 receptor (D2R) levels in the dorsal striatum (DS). G protein-coupled receptor kinases (GRKs) regulate desensitization, internalization, and recycling of these receptors, including the D2R. This study investigated the relevance of GRK2 and 3 (GRK2/3) in novelty-seeking behavior and striatal dopamine dynamics. Experimental Approach Individual novelty-seeking trait was assessed in Sprague Dawley rats using an open-field test. D2R, GRK2, and GRK5 protein levels were measured in synaptosomal DS samples using Western Blot. Pharmacological inhibition of GRK2/3 was assessed using Cmpd101. We tested the effect of systemic Cmpd101 administration on contextual novelty discrimination and local Cmpd101 perfusion on baseline and stimulus-evoked extracellular dopamine (DA) levels in the DS. Key Results Locomotor activity in a novel environment inversely correlated with the synaptosomal GRK2 and D2R protein levels in the DS. Systemic Cmpd101 treatment modulated the locomotor discrimination index in a novelty phenotype-dependent manner. Moreover, local Cmpd101 perfusion in the DS elicited a sustained elevation in basal extracellular dopamine levels and significantly blunted subsequent stimulus-evoked DA release, both effects independent of novelty-seeking phenotype. Conclusion and Implications Together, our findings link GRK2/3 signaling to individual differences in novelty-seeking and striatal dopaminergic function. These results suggest a potential relevance to drug addiction vulnerability.

Chronic ethanol consumption produces long-lasting effects on the brain that contribute to persistent behavioral changes. This has been modeled in animals using the chronic intermittent ethanol (CIE) paradigm, which induces escalation of consumption and alterations in affective and cognitive behavior. While this model has been well characterized in male subjects, the effects of CIE in females and long-term effects that persist beyond the acute withdrawal remain relatively underexplored. Here, female C57BL/6J mice were exposed to four weeks of chronic intermittent ethanol (CIE) vapor to induce dependence. Following CIE, mice were evaluated for physiological tolerance to ethanol and alterations in anxiety-like behaviors and memory processing. Using the ethanol responsivity battery (ERB) assay to assess physiological tolerance, we found blunted responsiveness to the intoxicating effects of ethanol in the CIE-exposed females, indicating heightened ethanol tolerance that persists beyond the acute withdrawal phase. A cohort underwent behavioral testing following CIE to characterize changes in anxiety-like behavior, exploration, and memory across abstinence. In early abstinence (<5 days post-CIE), CIE-exposed females showed increased exploratory behavior compared with Air controls. After one week of abstinence, CIE-exposed females displayed impaired object recognition memory. CIE-exposed females also showed increased anxiety-like behavior at protracted abstinence time points, exhibiting hyponeophagia in the novelty-suppressed feeding test at 2 weeks post-CIE. In addition, following cued fear conditioning, we found reduced extinction recall at 4 weeks post-CIE. Together, this work indicates that chronic alcohol exposure leads to increased alcohol tolerance and distinct, persistent alterations in memory and anxiety-like behavior in female mice.

Importance: Obsessive-Compulsive Disorder (OCD) has a 2% global prevalence, but only about 50% of patients respond to conventional treatment, underscoring the need for additional effective interventions. Objective: To assess the feasibility, safety, and preliminary evidence for efficacy of repeated psilocybin administration in OCD patients who had previously attempted psychotherapy or pharmacotherapy. Design: Waitlist-controlled open label randomized clinical trial. Setting: Data were collected at the Johns Hopkins University School of Medicine. Participants: Data were analyzed from 30 participants (total randomized N=37, by age, sex and OCD severity) with a failed previous attempt at either pharmacotherapy or evidence-based psychotherapies such as exposure response prevention (ERP). Intervention: Participants received two psilocybin doses over two weeks (20 mg followed by 30 mg, if well-tolerated) under supportive conditions. The immediate-treatment arm received the drug within a month following enrollment, and the waitlist-control arm received identical support and dosing after an 8-week waiting period. Main Outcomes: Clinician-administered Y-BOCS scores was collected one week post each drug administration and one month post session 2. Self-assessed reports were collected for acute subjective effects (Mystical Experience Questionnaire (MEQ), Challenging Experience Questionnaire (CEQ), and 11-Dimensional Altered States of Consciousness (11D-ASC)), State-Trait Anxiety Inventory (STAI), Beck Depression Inventory-II (BDI-II), and Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q). Results: A total of 37 participants were enrolled in the study (age[SD] years:38.4[11.6] years; 21 [56.75%] female), with 30 [81.08%] completing the 1-month follow-up. We show that two successive doses of psilocybin over two weeks were well-tolerated, leading to improvements in OCD symptoms. Compared with the waitlist group (N=14), the immediate-treatment group (N=16) showed a greater reduction in the Y-BOCS scores (F(2,56)=16.17, p<0.001). After crossover, this improvement persisted one month after the second psilocybin dose for both groups (F(3,84)=29.91, p<0.001). Reductions in Y-BOCS score post sessions were correlated with several acute subjective effects measures, including total scores on MEQ, and individual factors on CEQ and 11D-ASC. Conclusions and Relevance: Repeated psilocybin administration is tolerable and potentially efficacious in reducing OCD symptoms. These results support further investigation of multidose psilocybin protocols as a viable therapeutic approach. Trial Registration: ClinicalTrials.gov Identifier NCT05546658

A growing body of evidence demonstrates that signaling pathways of endogenous lipids (endolipids) modulate the reinforcing properties of opioids including reward and withdrawal. Many of these studies are focused on the endocannabinoid (eCB) system, and its primary eCB ligands, Anandamide (AEA) and 2-arachidonoylglycerol (2-AG). The central hypothesis is that modulation of the eCB system through eCB receptors and enzymes may improve therapeutic outcomes for opioid use disorder (OUD). However, outcomes in preclinical and clinical studies using the low efficacy, CB1/CB2 orthosteric agonist, THC, found limited to no effectiveness, suggesting that targeting this aspect of CB1/CB2 is not a useful therapeutic tool for OUD. Previous studies finding that genetic deletion or pharmacological inhibition of endolipid-regulating enzymes (including eCBs) can alter behavioral sensitivity to opioids provide insight into an alternative approach. If opioid use dysregulates a wide range of endolipid biosynthesis and metabolism, then a clearer understanding of these changes, especially in signaling ligands, will provide a novel avenue to both understand the underlying physiological changes with opioid use as well as providing novel targets for therapeutic interventions. In this study, we tested the hypothesis that if morphine dysregulates multiple endolipid signaling systems in the brain and body, and this dysregulation evolves over time, then these differential effects will be measurable by changes in endolipid levels. Using an Acute (30 minutes post injection 20mg/kg) and a Chronic paradigm (5 days, twice daily, 20mg to 100mg/kg escalating dose) we measured 100 targeted endolipids in 8 brain regions, plasma, liver, and feces in male mice. In the Acute condition, we found that the most screened endolipids were changed in the striatum (42%), while the fewest were changed in the thalamus (19%) and 38% in the plasma. In the Chronic condition, 79% of plasma endolipids were changed. The highest level of change in the CNS was in the cortex (39%). Levels of AEA and 2-AG were largely unchanged; however, levels of the N-acyl GABAs, N-acyl valines, N-acyl taurines, and specific bile acids (e.g. DCA, TCA) showed the most dynamic changes by treatment group. These results provide information on novel endolipid signaling pathways that may contribute to the unwanted side effects of opioids, such as dependence and withdrawal, and provide novel avenues for the development of therapeutic strategies.

Genetics shape cocaine behavior and abuse liability, but the underlying neurophysiological effects remain understudied. In male C57BL/6J, B6129SF2/J, and DO/J mice, we report conserved and divergent cocaine induced neuroplasticity in the accumbens shell following 5 days of cocaine and 10 to 14 days of abstinence.

Circadian clock genes in the striatum modulate alcohol drinking behavior in female mice, but the underlying synaptic mechanisms remain unknown. Medium spiny neurons (MSNs) of the striatum express D1- or D2-type dopamine receptors, which are differentially modulated by alcohol. Here we used whole-cell patch-clamp recordings to examine how deletion of the clock gene Bmal1 affects spontaneous excitatory postsynaptic currents (sEPSCs) in electrophysiologically identified D1 and D2 neurons of the female mouse dorsomedial striatum (DMS). Prior intermittent access to alcohol increased sEPSC amplitude in putative D1 neurons of wildtype mice without affecting sEPSC frequency, and this increase was accompanied by greater dendritic branching and complexity in biocytin-filled D1 MSNs. Bmal1 knockout had the opposite effect in D1 neurons, reducing sEPSC amplitude in both alcohol-exposed and alcohol-naive animals. In D2 neurons, alcohol produced only a non-significant trend toward increased sEPSC amplitude in wildtype mice, but a significant increase in Bmal1 knockout mice. Thus, local disruption of Bmal1 appears to block the alcohol-induced enhancement of sEPSCs in D1 neurons while unmasking a similar enhancement in D2 neurons. These findings may help explain how Bmal1 deletion in the DMS reduces alcohol consumption in female mice.

Pavlovian bias, a motor bias driven by emotionally-valenced context, has long been considered a proxy for emotion-action processing, which may become aberrant in affective disorders and suicidality. The orthogonal valenced Go/NoGo paradigm was developed to isolate this bias and has been widely adopted in translational psychiatry research under this interpretation. However, several unresolved theoretical inconsistencies highlight the need to dissociate potential confounding factors within this paradigm before assigning mechanistic and clinical interpretations to its findings. Using a novel paradigm that fully orthogonalized valence, action, and aimed transition in a normative sample of 25 individuals, we found that the "active escape bias" previously observed in aversive contexts--and interpreted as reflecting suicidality in the clinical population--was reproduced in appetitive contexts using trials with the same transition structure. Furthermore, computational modeling indicated that the bias patterns isolated by the orthogonal paradigm are primarily explained by the combined effects of aimed transition and cue salience, without requiring emotional-valence modulation. These findings call for a fundamental reconsideration of how orthogonal Go/NoGo paradigms are interpreted in translational psychiatry, particularly how the behavior they isolate is mechanistically linked to affective symptoms.

Background: Social difficulties in alcohol use disorder (AUD) have been linked to alterations in social cognition, including increased egocentric bias. Psychedelics such as psilocybin have been proposed to modulate self-related processing, but their effects on specific socio-cognitive mechanisms remain unclear. Methods: In this randomized controlled pilot study, recently detoxified individuals with AUD with persistent depressive symptoms completed a visual perspective-taking task before and after a psilocybin session (25 mg dose vs active placebo 1 mg psilocybin). Results: The 25 mg psilocybin group showed a significant reduction in egocentric bias and egocentric superiority on reaction times, with no effect on altercentric bias nor on accuracy. Between-group comparisons confirmed greater reductions in the high-dose relative to the low-dose group. The high-dose group reported more intense subjective psychedelic experiences, and greater subjective intensity was associated with lower egocentric superiority in accuracy. Conclusions: These findings provide preliminary evidence that psilocybin may selectively reduce egocentric interference in individuals with AUD, suggesting a decrease in egocentricity rather than enhanced sensitivity to others. Although replication in larger samples is needed, reduced egocentricity may represent one mechanism through which psilocybin influences social cognition in AUD. Clinical trial registration: ClinicalTrials.gov, https://clinicaltrials.gov/study/NCT06235411, NCT06235411.

Background: ADHD is characterized by inattention and impulsivity. Stimulants such as amphetamine are the first line treatments for ADHD. Amphetamine (AMPH) works by increasing extracellular levels of dopamine and noradrenaline. Such stimulants are used to test predictive validity of animal tasks, where it has been reported that amphetamine improves rat 5-CSRTT accuracy when the session length is increased to 250 trials. This improvement in accuracy was observed later in the session as control performance declined. Proving that amphetamine can improve 5C-CPT task performance adds to the predictive validity of the task. No previous works has demonstrated the pro-attentional effects of amphetamine on sustained attention in rat 5C-CPT. We have previously shown that pharmacological manipulations of dopaminergic system improve waiting impulsivity in a rate dependent manner and the importance of analysing the data using Oldham method. The present study extends this work to investigate the effect of amphetamine on attentional processes. Objective: to investigate effects of amphetamine on attentional processes as measured by 5C-CPT task using correlational analysis and group performance. Methods: Trained female Lister hooded rats were tested with AMPH (0.1, 0.2 and 0.4 mg/kg) under reduced stimulus duration schedule (0.25,0.5,1,1.5 and 2s SD) over normal length session (120 trials). Correlational analysis (Oldham method) was used to understand the relationship between baseline performance measures and the change following administration of AMPH. Results: The highest dose of AMPH impaired attentional performance in the 5C-CPT under reduced SD challenge (0.5s,1s,1.5s and 2s). This impairment was due to increase in FAR. Previous studies in 5-CSRTT suggest that reducing the SD increases attentional demand in the form of reducing accuracy without affecting waiting impulsivity. However, the 5-CSRTT does not include non-target trials, therefore, it cannot be used to measure sustained attention (SI) and responsivity index. The 5C-CPT requires greater attentional resources than the 5-CSRTT.This study is the first to report that reducing the SD changes responsivity index (bias) rather than measures of sustained attention (sensitivity index) in the 5C-CPT. Control sensitivity index did not change until the SD was reduced to less than 0.5s and this change was due to a change in baseline responsivity index (bias). Performance under each reduced SD revealed that the highest dose of AMPH (0.4 mg/kg) showed a tendency toward reducing sensitivity index at 0.5, 1.0 and 1.5s SDs. Under 1.0s SD, the highest dose of AMPH changed sustained attention (SI, HR and FAR) and omission in a rate-dependent manner without changing responsivity index. Performance across the session revealed that the impairment in sustained attention was observed at the beginning of the session. In the third trial block, Oldham method revealed an inverse relationship between baseline accuracy and the change following administration of 0.2 mg/kg AMPH, indicative of a rate-dependent effect. Conclusions: This study successfully demonstrates rate-dependent effects of AMPH on measures of attentional performance in the 5C-CPT. This experiment also demonstrates that responsivity index is sensitive to reduced SD challenge. To our knowledge this is the first study to report the presence of a direct relationship between baseline sustained attention and magnitude of improvement following administration of 0.4 mg/kg AMPH and an inverse relationship between baseline accuracy and the change following administration of 0.2 mg/kg AMPH in 5C-CPT task. Future studies should test lower doses of amphetamine (0.05 and 0.1 mg/kg) over extended session length (250 trials) to reveal the pro-attentional effects of this drug on 5C-CPT performance measures.

Background: Deficits in inhibitory control are considered a central feature of alcohol use disorder (AUD), yet behavioral and neuroimaging findings have been inconsistent. One potential explanation is the marked heterogeneity of AUD, which encompasses multiple symptom dimensions that may differ in their underlying neurocognitive mechanisms. In this study, we investigated whether behavioral and neural markers of inhibitory control are associated with specific DSM-5 AUD symptom domains. Methods: A total of 589 participants (432 with non-treatment seeking AUD, 157 controls) completed a Stop-Signal Task (SST) during fMRI. Associations between DSM-5 symptom domains (impaired control over alcohol use, risky use, social problems, physical dependence) and SST performance, inhibition-related brain activation, and alcohol consumption were examined. Real-life drinking behavior was additionally assessed over 12 months using ecological momentary assessment (EMA). Results: Greater impaired control symptom severity was associated with poorer performance on go trials and diminished post-error slowing during SST. At the neural level, higher impaired control symptom severity was associated with reduced activation across fronto-insular, parietal, cingulate, supplementary motor, and cerebellar regions. In contrast, other symptom domains showed little to no associations with inhibition-related behavioral or neural measures. Higher impaired control symptom severity was associated with greater alcohol consumption across questionnaire-based and EMA-based assessments. Conclusions: In this large cohort, altered behavioral performance and recruitment of inhibition-related brain regions in the SST was selectively linked to impaired control symptoms. These findings highlight the importance of symptom-based approaches for understanding heterogeneity in addiction and may inform the development of more targeted interventions.

Opioid withdrawal drives continued opioid use in opioid use disorder (OUD), which affected an estimated 4 million Americans in 2024. However, only one non-opioid medication is FDA-approved for withdrawal treatment, and there is great need for more diverse treatment options. Mice are powerful models to study opioid withdrawal because they allow for controlled drug and environmental exposure, express OUD-relevant phenotypes, and provide access to withdrawal-relevant tissue at exact time points. However, mouse models are hindered by their over reliance on a single genetic background (C57BL/6J). Using a single background risks limiting the translatability of preclinical studies as they are projected into genetically diverse human populations. Inferring withdrawal intensity in mice typically relies on single behaviors or indexes of behaviors, and applying these approaches across mouse genetic diversity faces a critical challenge: differing withdrawal responses could either encode differences in withdrawal severity, or differences in withdrawal-evoked behaviors independent of severity. To overcome this limitation, a more comprehensive assessment of opioid withdrawal behaviors across mouse genetic diversity is needed. Here we leverage computer vision and machine learning to automate the simultaneous quantification of many mouse behaviors during opioid withdrawal in eight diverse strains of mice. We reveal that all eight strains exhibit withdrawal-evoked behaviors, and these behaviors are sufficient to identify the withdrawal state of the mouse. However, the effect of withdrawal on individual behaviors or indexes of behaviors is not uniform across genetic diversity, and extending methods tuned in one strain risks misclassifying withdrawal in others. Finally our approach was able to distinguish graded withdrawal intensity, as defined by opioid exposurewithin3of4strainstested. We therefore conclude that opioid withdrawal behavior is profoundly shaped by genetic background, but withdrawal severity can nonetheless be established within a background. Combining automated computer-vision phenotyping with genotype-aware modeling provides a scalable path toward genetically informed withdrawal assessment in diverse mouse populations, with the ultimate goal of identifying the genetic and biological networks that modulate opioid withdrawal and may represent new targets for treating opioid use disorder.

Alcohol use disorder is associated with persistent neuroadaptations and cognitive impairments, particularly during withdrawal, yet the temporal dynamics and interactions between these processes remain poorly understood. In the present study, we investigated time-dependent alterations in the oxytocin receptor (OTR), -opioid receptor (MOPr), metabotropic glutamate receptor 5 (mGlu5R), and translocator protein (TSPO) following chronic ethanol exposure and withdrawal, and their relationship to behavioral impairments. Male C57BL/6J mice were exposed to a 10-day escalating-dose ethanol liquid diet paradigm followed by 1, 4, or 7 days of withdrawal. Motor coordination and recognition memory were assessed using rotarod and novel object recognition tests, and receptor binding was quantified using autoradiography across multiple brain regions. Chronic ethanol exposure induced motor deficits that persisted during early withdrawal, whereas recognition memory impairments emerged after 7 days of withdrawal. Ethanol exposure and withdrawal produced region- and time-dependent alterations across all systems examined, with increased OTR binding in septal regions and transient reductions in basomedial amygdala OTR binding during intermediate withdrawal that normalized following prolonged withdrawal, transient increases in MOPr binding in striatal regions at 4 days of withdrawal, increased mGlu5R binding in the nucleus accumbens core, basolateral amygdala, and hippocampus, and early transient increases in TSPO binding indicative of neuroimmune activation. Notably, mGlu5R binding in the caudate-putamen and amygdala was associated with recognition memory deficits in a withdrawal stage-dependent manner. Bioinformatic analysis of human postmortem hippocampal transcriptomic datasets from individuals with alcohol use disorder revealed no consistent changes in GRM5 expression, suggesting that mGlu5R dysregulation may be driven by post-transcriptional mechanisms. These findings demonstrate that ethanol withdrawal is characterized by temporally distinct neuroadaptations across multiple systems and identify mGlu5R as a key correlate of withdrawal-associated memory impairment, highlighting its potential as a translational therapeutic target.

Animal studies primarily rely on human monitoring for health and behavioral outcomes. The presence of a human, however, can induce stress and potentially alter experimental results. We sought to answer whether human observation alone is enough to change experimental outcomes and obscure the effect of interest. Our automated home-cage behavioral phenotyping system provided the ideal platform to test this hypothesis. Two cohorts received semaglutide (0.03 mg/kg, intraperitoneally) on separate consecutive days. The first cohort was recorded without inspection after dosing; the second underwent a brief visual health check with no handling. Recordings from the checked cohort on the preceding day, without injection or inspection, provided a matched baseline. A single brief check produced large, time-locked changes across the behavioral repertoire. The changes began before the cage door was opened, indicating a response to experimenter proximity. In addition to adding variance, the semaglutide-treated animals' behavior during observation was more similar to the no-injection baseline than to the semaglutide/no-check reference, transiently erasing the drug phenotype. Brief human observation is therefore not a neutral measurement operation; over the minutes surrounding it, it is a perturbation in itself that is large enough to mask the drug effect it is meant to record.

BackgroundSerotonergic signaling plays an important role in the modulation of absence seizures (ASs), and activation of serotonin 2A receptors (5-HT2ARs) with TCB-2 suppresses spontaneous absence seizures (ASs) in Genetic Absence Epilepsy Rats from Strasbourg (GAERS). Lisuride is a pharmacologically complex serotonergic and dopaminergic ligand with low 5-HT2AR signaling efficacy and a receptor profile distinct from that of TCB-2. We therefore investigated its effects on spontaneous ASs and the contribution of 5-HT2ARs to its actions. MethodsThe effects of systemic lisuride (0.1 and 0.5 mg/kg) on spontaneous ASs were examined in freely moving GAERS over 120 min by quantifying time spent in seizure, mean seizure duration and seizure number. The contribution of 5-HT2ARs was investigated by administering lisuride (0.5 mg/kg) following pretreatment with the selective 5-HT2AR antagonist MDL11,939 (0.5 mg/kg). ResultsLisuride produced marked dose- and time-dependent effects on ASs. At 0.1 mg/kg, lisuride elicited modest pro-absence effect. In contrast, 0.5 mg/kg produced a pronounced biphasic response, with a marked reduction in seizure activity during the first 40 min, followed by rebound increase during the second hour. The early suppression involved reductions in both seizure number and duration, whereas the delayed pro-absence effect was predominantly associated with prolonged ASs. MDL11,939 did not prevent the early seizure suppression but blocked the increase in seizure duration while producing a transient increase in seizure number. ConclusionsLisuride is a dose- and time-dependent bidirectional modulator of ASs in GAERS. The persistence of the profound early anti-absence effect during 5-HT2AR blockade indicates that this response does not require 5-HT2AR activation, whereas the modification of the delayed response by MDL11,939 supports a 5-HT2AR-dependent component in the later phase. These findings distinguish lisuride pharmacologically from TCB-2 and suggest that its biphasic effects arise from the dynamic engagement of multiple receptor mechanisms, potentially including dopaminergic signaling.

Negative emotional bias, including reduced processing of positive information and negative interpretation of ambiguous stimuli, is a core feature of depression. Esketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist with rapid antidepressant effects in treatment-resistant depression (TRD), reduces depressive symptoms, but its effects on distinct components of emotional processing remain unclear. Fifty-three patients with TRD and 53 healthy controls performed an Emotional Facial Expression Morphing task. Patients were assessed at baseline, 24 hours after the first esketamine administration, and after 4 weeks of treatment. Statistical models examined detection thresholds for happy and sad faces, negative categorisation of neutral faces, and signal detection indices separating emotion-neutral discrimination sensitivity (d') from response criterion (c), indexing the evidence required to report the presence of an emotion. At baseline, patients required greater happy-face intensity for emotion detection and were more likely to categorise detected neutral faces as negative. They also showed a more conservative response criterion without group difference in discrimination sensitivity. Responders showed an early increase in d'; and, by week 4, less negative categorisation of neutral faces than non-responders. A lower baseline response criterion was associated with responder status and, in secondary continuous analyses, with greater subsequent MADRS improvement. These findings indicate that TRD involves abnormalities across detection-related, valence-related, and decisional aspects of facial-emotion processing that are differently associated with esketamine response: baseline response criterion emerged as a candidate prognostic marker, whereas negative categorisation of neutral faces tracked clinical response. Assessing these domains may inform clinical evaluation, pending independent replication.

Opioid use disorder (OUD) remains a major public health concern, with potent synthetic opioids driving overdose deaths. Understanding how synthetic opioids like fentanyl alter brain circuits to promote persistent use is critical for advancing OUD treatment. The ventral tegmental area (VTA), which projects to several other brain regions including prefrontal cortex (PFC), nucleus accumbens (NAc) and amygdala (Amy), contributes to both the euphoric and dysphoric phases of OUD. Projection target influences the baseline properties and opioid-induced neuroadaptations of VTA neurons, yet less is known about the molecular adaptations that occur across distinct VTA projections during spontaneous opioid withdrawal. Here, we investigated transcriptional responses to acute spontaneous fentanyl withdrawal in projection-defined VTA neurons. Following chronic fentanyl exposure and 24h of spontaneous withdrawal in male and female mice, we sequenced ribosome-associated RNA from VTA neurons projecting to PFC, NAc, or Amy. We found that fentanyl withdrawal produced divergent transcriptional adaptations in VTA neurons projecting to PFC compared with VTA-NAc and VTA-Amy neurons, whereas adaptations in VTA-NAc and VTA-Amy neurons were more concordant. Weighted gene co-expression network analysis (WGCNA) identified fentanyl-responsive modules across VTA projections, with gene ontology analysis linking these modules to distinct biological processes. We further used regulatory enrichment analysis to identify candidate transcriptional regulators associated with fentanyl-responsive co-expression modules. Together, our data demonstrate that VTA neurons undergo distinct molecular adaptations during fentanyl withdrawal based on their projection target, providing new insight into molecular mechanisms relevant to OUD.

Objectives: Opioids disrupt sleep, but how repeated exposure reorganizes thalamocortical networks is unknown. We asked whether morphine alters sleep architecture, regional oscillations, and phase synchronization, and how exposure history modifies these effects. Methods: From mice, we analyzed cortical electroencephalogram (EEG), central medial thalamic (CMT) local field potentials (LFP), and electromyography (EMG) for 24h after the first and fourth injections of morphine and in abstinence, and quantified vigilance-state occupancy, spectral power, state-power correlations, and the weighted phase-lag index (wPLI), which minimizes volume conduction. Results: Morphine produced hyperlocomotion, wake promotion persisting with repeated exposure, non-rapid eye movement (NREM) sleep suppression, complete rapid eye movement (REM) sleep loss, and rebound sleep. Cortex and thalamus dissociated: in NREM sleep after the first injection, cortical delta and low-gamma power increased, while CMT delta, theta, alpha, and beta power decreased. NREM occupancy coupled more strongly to CMT delta and theta power after both injections, whereas cortical wake correlations in theta, alpha, and beta fell and reversed during abstinence. Overall synchronization was altered only in theta and alpha: corticocortical alpha synchronization decreased acutely, and repeated exposure reduced thalamocortical theta synchronization in wake and NREM sleep. During abstinence, sleep architecture and synchronization largely normalized while spectral and state-power abnormalities persisted alongside mechanical hypersensitivity. Conclusions: We found that morphine does not merely reduce sleep; it reorganizes it: cortex and CMT move in opposite directions, thalamocortical phase synchronization is redistributed, and the resulting spectral and state-power abnormalities outlast the recovery of sleep architecture itself rather than producing tolerance.

Background: Alcohol and cannabinoids are frequently used during pregnancy, however their combined effects on offspring outcomes are currently under-investigated. In this study, co-exposure was compared to single-drug and drug-free exposures for influences on adult alcohol-seeking and cannabinoid system proteomics. Methods: Pregnant C57BL/6J mice received ethanol vapor (ALC), CP-55,940 (0.75 mg/kg; CB), both (ALC+CB), or neither on gestational days 12-15. Beginning on Postnatal Day 200, male and female offspring underwent home-cage ethanol drinking (N=108) and operant self-administration, progressive-ratio, extinction, and reinstatement testing (N=96). CNR1 and CNRIP1 protein abundance was quantified in the medial prefrontal cortex (mPFC) and dorsomedial striatum (N=57) and compared to within-subject drinking behaviors. Results: Prenatal CB exposure increased cumulative home-cage ethanol intake, primarily in males. At 40% ethanol under progressive-ratio schedules, ALC+CB males consumed more than all other male groups, whereas all exposed female groups consumed more than controls. ALC+CB males also showed greater extinction responding than all other male groups and greater reinstatement intake relative to baseline than CON and ALC males. ALC+CB increased mPFC CNR1 in males relative to all other groups, whereas CB and ALC+CB reduced mPFC CNR1 in females. Higher mPFC CNR1 was associated with fixed-ratio and 40% progressive-ratio intake, extinction, and reinstatement exclusively in males. Conclusions: Prenatal co-exposure produced a persistent male phenotype of enhanced ethanol seeking that was distinct from either exposure alone and accompanied by elevated mPFC CNR1. This behavioral and molecular convergence justifies future investigations manipulating corticostriatal cannabinoid signaling to attenuate exposure-induced ethanol consumption in late adulthood.