Neuropsychopharmacology

Cannabis is the most common illicit drug abused worldwide, and its consumption has substantially increased among pregnant women. We previously demonstrated that male preadolescent offspring prenatally exposed to {Delta}9-tetrahydrocannabinol (THC), a model of prenatal cannabinoid exposure (PCE), exhibit a mesolimbic dopamine (DA) neuron dysfunction contributing to at-risk psychotic-like (endo)phenotypes that are unmasked by acute THC exposure at preadolescence. Dysregulation of mesocortical DA signaling along with prefrontal cortex (PFC) function is also a central feature of psychotic disorders. Furthermore, studies investigating the impact of PCE on PFC in the offspring at preadolescence, a window of heightened plasticity and vulnerability, are limited. To fill this gap, we applied a multiscale analysis of mesocortical DA transmission and PFC function in PCE preadolescent offspring by integrating behavioral, neurochemical, electrophysiological, and molecular approaches. PCE enhanced spontaneous repetitive behaviors in a male-specific manner. PCE also abolished sex differences in the intrinsic excitability of PFC pyramidal neurons and Netrin-1 expression. In addition, PCE altered the expression of genes associated with endocannabinoid signaling without changing basal and THC-induced extracellular levels of DA in the PFC. Collectively, these findings demonstrate that prenatal THC exposure disrupts both proper maturation and sexual differentiation of PFC circuitry, thus extending the impact of PCE from previously described mesolimbic abnormalities to mesocortical pathway. Finally, our data identify early cortical molecular and cellular alterations that may contribute to neuropsychiatric vulnerability later in life. Highlights* Preadolescent male rats exposed in utero to THC display repetitive behavior * Prenatal cannabinoid exposure (PCE) does not alter dopamine transmission in the PFC * PCE potentiates AMPA-mediated transmission in male pyramidal cells * PCE abolishes sex differences in Netrin-1 expression levels in the PFC

Relapse following prolonged abstinence is a primary challenge in the treatment of opioid and cocaine use disorders, driven in part by enduring dysfunction of medial prefrontal cortex (mPFC) circuits that impair inhibitory control over drug-seeking. The molecular substrates underlying this dysfunction, and whether they differ across drug classes, remain unknown. Here, we performed label-free quantitative proteomics of mPFC synaptosomes isolated from rats after 30-day abstinence following intravenous heroin or cocaine self-administration to profile synaptic adaptations that may contribute to relapse vulnerability. Heroin abstinence induced extensive synaptic proteomic remodeling characterized by coordinated downregulation of mitochondrial proteins involved in oxidative phosphorylation, including pyruvate dehydrogenase complex subunits that regulate carbon entry into mitochondrial metabolism. Targeted metabolomic profiling of whole mPFC revealed accumulation of upstream glycolytic and pentose phosphate pathway intermediates, consistent with altered pyruvate utilization and mitochondrial oxidation. Several bioenergetic metabolites also correlated positively with the severity of escalation of heroin intake. Consistent with the bioenergetic remodeling observed during protracted heroin abstinence, whole-cell patch-clamp recordings from layer V mPFC pyramidal neurons revealed lasting suppression of intrinsic excitability and a decreased spontaneous excitatory synaptic activity. Cocaine abstinence, by contrast, produced limited changes in synaptic bioenergetics while inducing a distinct cytoskeletal remodeling signature. Overall, these findings identify synaptic bioenergetic remodeling as a previously underappreciated feature of prolonged heroin abstinence and reveal a marked divergence in the molecular adaptations induced by heroin versus cocaine within the mPFC. These results implicate mitochondrial bioenergetic pathways as therapeutic targets for reducing relapse vulnerability specifically associated with opioid use disorder.

N, N-dimethyltryptamine (DMT) and 5-methoxy-N, N-dimethyltryptamine (5-MeO-DMT) are structurally related tryptamine psychedelics with emerging therapeutic potential, yet their comparative acute pharmacology and longer-term neuroplastic effects remain incompletely defined. Here we show that DMT produces a bell-shaped dose-response curve in the mouse head-twitch response (HTR) assay, whereas 5-MeO-DMT elicits a monotonic increase. Selective antagonism at 5-HT2A or 5-HT1D receptors, or agonism at 5-HT1A, robustly attenuates HTR for both compounds without abolishing their ability to reduce marble burying, a screening assay for OCD-like behavior. Acutely, both agents elevate TrkB phosphorylation in a region-specific manner, with broader engagement by DMT across default-mode-network and hippocampal territories. Twelve days after a single dose, both compounds increase synaptic proteins (PSD-95, synaptophysin; SV2A for DMT), while DMT uniquely lowers hippocampal BDNF and reprograms frontal-cortex glutathione and energy metabolism. These findings demonstrate that acute hallucinogenic-like activity and selected therapeutic-like behavioral and plasticity outcomes can be pharmacologically dissociated, informing the rational design of more tolerable, scalable psychedelic-based treatments.

Post-traumatic stress disorder (PTSD) is a highly prevalent, debilitating psychiatric condition. Existing treatments are ineffective for many patients. 3,4- methylenedioxymethamphetamine (MDMA)-assisted psychotherapy has demonstrated substantial clinical efficacy but relies on prolonged, resource-intensive therapeutic protocols that limit scalability and accessibility. Here, we investigated whether combining MDMA with exposure-based intervention could enhance therapeutic efficiency in a preclinical model of PTSD-like behavior. Using a learned helplessness paradigm in mice, we identified trauma-susceptible individuals based on persistent escape failures following inescapable stress. Traumatised mice subsequently received brief treatment regimens consisting of MDMA or saline vehicle administered with or without exposure to the traumatic cue. Behavioral outcomes were tracked longitudinally using active avoidance performance as the primary endpoint, complemented by assays of anxiety- like, depressive-like, cognitive, and social behaviors. MDMA treatment markedly reduced trauma-associated behavioral deficits. MDMA combined with exposure produced rapid and sustained recovery compared to control conditions. Statistical analyses revealed significant treatment- and time-dependent effects on avoidance behavior, indicating accelerated resilience acquisition in MDMA-treated groups. Additional behavioral assays demonstrated dose-dependent effects of MDMA on anxiety- and depression-related measures. Together, these findings provide proof-of-principle that pharmacological modulation with MDMA can enhance exposure-driven behavioral recovery, supporting a strategy to integrate MDMA into more efficient and accessible PTSD treatment frameworks. This work establishes a preclinical foundation for clinical studies aimed at optimizing MDMA-assisted interventions to improve scalability and patient access.

BackgroundAlthough nicotine reinforcement is often attributed to mesolimbic dopamine neurons in the ventral tegmental area, accumulating evidence indicates that additional brain circuits contribute to its reinforcing effects. AimsThe hypothalamic supramammillary region (SuM) has been implicated as one such substrate, yet the cellular targets and circuit mechanisms through which nicotine engages this region remain poorly understood. MethodsWe combined RNAscope in situ hybridization to identify nicotinic acetylcholine receptor (nAChR) subunits, intravenous nicotine self-administration in mice to determine doses that reliably support reinforcement, and fiber photometry to monitor calcium activity in SuM VGluT2 neurons in vivo. ResultsMice exhibited reliable nicotine self-administration across a range of doses under fixed-ratio and progressive-ratio schedules. RNAscope analysis revealed prominent expression of the {beta}2 nAChR subunit in VGluT2-expressing neurons projecting from the SuM to the medial septum. Fiber photometry recordings showed that reinforcing doses of nicotine produced rapid, infusion-locked increases in GCaMP signals in SuM VGluT2 neurons. ConclusionsThese findings identify nAChR-expressing SuM neurons as a candidate circuit substrate engaged by reinforcing doses of nicotine and extend current models of nicotine reinforcement beyond canonical mesolimbic dopamine pathways.

GLP-1 agonist drug repurposing efforts may establish new clinical niches in managing psychiatric and neurological disorders. However, a comprehensive understanding of GLP-1 neurobiology and an appreciation of specific neural mechanisms by which GLP-1 agonists might provide therapeutic effects is limited and stands as a barrier to these efforts. When considering current preclinical research evaluating GLP-1 agonist central mechanisms, a considerable knowledge gap remains regarding which specific cellular populations and systems define potential therapeutic effects in the brain. In this research, we used cFos immunohistochemistry to identify specific neuronal populations that exhibited altered cellular activity following acute administration of semaglutide to rats. We found that the orexin/hypocretin and basal forebrain cholinergic systems are activated following acute semaglutide administration in male and female young adult rats (3-5 months). Informed by the results of our histological analysis, we next employed in vivo microdialysis to test our hypothesis that semaglutide would acutely increase acetylcholine release in the rodent hippocampus. Here, we report that semaglutide acutely increases acetylcholine efflux in the ventral hippocampus of conscious and freely moving rats regardless of biological sex in both young adult and aged rats (23-26 months). Given the relevance of hippocampal cholinergic neurotransmission in learning and memory, our research mechanistically connects GLP-1 agonists with established targets in cognitive decline and dementia.

Dysregulation of the delta-type glutamate receptor GluD1 and N-methyl-D-aspartate receptors (NMDARs) is implicated in neuropsychiatric disorders including schizophrenia and intellectual disability, and GluD1 modulates NMDAR response in hippocampal neurons. However, the precise mechanisms by which GluD1 influences specific NMDAR subtypes remain undefined, representing a critical gap given the reliance of synaptic plasticity and cognition on NMDAR composition. GluN2A- and GluN2B-containing NMDARs are essential for synaptic long-term potentiation (LTP) and contextual learning and memory. Here, we used CRISPR/Cas9 to generate GluD1 knockout (KO) in cultured hippocampal neurons and observed a selective decrease in GluN2B-containing NMDAR responses. In acute hippocampal slices, GluD1 KO similarly reduced GluN2B-containing NMDAR currents at ventral CA1[->]subiculum synapses and impaired LTP at these synapses. In vivo, region-specific GluD1 deficiency in the ventral subiculum disrupted long-term contextual memory, indicating a critical role for GluD1 in cognitive processes. These findings demonstrate that GluD1 is indispensable for preserving GluN2B-containing NMDAR function, synaptic plasticity, and memory, providing molecular insight into how GluD1 regulates NMDAR subtypes implicated in synaptic dysfunction in neuropsychiatric disorders. Understanding this mechanism will guide the development of therapeutic strategies that selectively target GluD1-dependent modulation of NMDAR subtypes in brain disease.

Adults aged [≥]65 years are increasingly using cannabis products. However, controlled pharmacokinetic and pharmacodynamic data on {Delta}9-tetrahydrocannabinol (THC) in this population are sparse, and remain limited to oral/oromucosal formulations. To characterize the acute pharmacokinetic and pharmacodynamic effects of oral and vaporized THC in healthy adults aged [≥]65, we conducted a two-arm, randomized, double-blind, placebo-controlled trial in which 20 participants (mean age 70.0, SD: 5.1 years) received oral (placebo, 5 mg, or 10 mg) or vaporized THC (placebo, 2 mg, or 4 mg) across three eight-hour sessions separated by [≥]72 hours. Outcomes included plasma pharmacokinetics, subjective drug effects, reinforcement value, cognitive performance, heart rate (HR), blood pressure (BP), and adverse events (AEs). Oral THC was associated with delayed, lower THC exposure (Tmax 60-90 min; Cmax 2.6-6.2 ng/mL), with 11-OH-THC concentrations approximately matching parent-THC; slow-rising subjective effects; no change in reinforcement value; no significant change in HR or BP; and no AEs. Vaporized THC was associated with rapid, THC-dominant exposure (Tmax 3 min; Cmax 24.6-53.8 ng/mL) and minimal 11-OH-THC concentrations; rapid-onset subjective effects; increased reinforcement value at 4 mg; and significant HR elevation peaking within 5 min, without significant BP change. Cognitive performance did not differ from placebo at any oral or vaporized THC dose. At vaporized THC 4 mg, two participants experienced five AEs. Oral and vaporized THC produce route-specific pharmacokinetic and pharmacodynamic profiles in adults aged [≥]65, including an increase in reinforcement value only after vaporization, and should therefore not be treated as interchangeable in risk assessment for older adults.

Disturbances in the CA2-subfield of the hippocampus have been associated with symptoms of psychiatric disorders, including impaired social behavior. Using chemogenetic inhibition during functional ultrasound imaging, we found that dorsal CA2 pyramidal neurons broadly control prefrontal and thalamic communication, in addition to hippocampal and thalamic activity. Correspondingly, chronic CA2 inhibition altered social interaction.

Psilocybin acutely alters neurotrophic, neurochemical, and immune markers, but the relationships between these responses and circulating microRNAs (miRNAs), i.e. non-coding RNAs that regulate post-transcriptional gene expression, remain unclear. In a randomized, double-blind, placebo-controlled study of 62 healthy adults who received psilocybin (0.17 mg/kg) or placebo, we previously demonstrated that let-7g-5p and miR-150-5p were transiently differentially expressed 360 minutes after psilocybin administration. Here, we examined whether changes in these miRNAs were associated with concurrent neurotrophic, inflammatory, pharmacokinetic, and glutamatergic measures. Expression changes from baseline to 360 min and 7 days were analysed using linear regression against changes in BDNF, TNF-, IL-6, C-reactive protein, cortisol, medial prefrontal cortex glutamate/total creatine, and psilocin concentrations. Psilocybin increased let-7g-5p and decreased miR-150-5p expression. Changes in let-7g-5p were positively associated with psilocin concentrations, suggesting sensitivity to inter-individual pharmacokinetic variability, whereas miR-150-5p showed no concentration-dependent association. In both groups, miRNA changes were negatively related to baseline expression: lower baseline let-7g-5p predicted larger increases, whereas higher baseline miR-150-5p predicted larger decreases. BDNF changes were associated with both miRNAs under placebo but not psilocybin, consistent with reduced between-subject variability and a flattened BDNF-miRNA relationship following treatment. Medial prefrontal glutamate was negatively associated with miR-150-5p change under psilocybin. No associations were found with immune biomarkers. Together, these findings support the predicted involvement of let-7g-5p and miR-150-5p in neuroplasticity and their potential as accessible blood-based biomarkers of individual neurobiological responsiveness to psilocybin and other psychedelics.

Psilocybin is a psychedelic which has been shown to induce neural plasticity through activation of intracellular serotonergic 5-HT2A receptors. It also produces brain-wide changes in structural and functional connectivity and holds promise as a therapeutic compound for treating anxiety and depression. Despite links between psilocybin-induced plasticity, the psychedelic experience, and reduction in depressive symptoms, little is known about the effects of psilocybin on the function of the highly plastic hippocampus, a region crucial for memory whose dysfunction is linked to neural disorders such as depression and anxiety. In this study, we investigated the acute and lasting effects of psilocybin on rodent sharp-wave ripples (SWRs), transient high frequency oscillations observable in the hippocampal local field potential which are linked to memory consolidation. We found that a 10 mg/kg dose of psilocybin robustly decreased the peak SWR frequency and increased the duration of SWRs immediately following administration compared to control sessions the day before and after. Psilocybin also perturbed sleep architecture, resulting in a pronounced reduction in non-rapid eye movement (NREM) sleep which lasted for hours. Therefore, psilocybin could impact memory processing by modulating hippocampal SWRs.

While excess tonic dopamine signalling is a hallmark of schizophrenia and psychotic disorders, it has been difficult to reconcile with dopamine-dependent learning deficits seen in schizophrenia. Excess spontaneous activity of tonic dopamine neurons, coupled with reduced coordinated activity of phasic dopamine neurons, may explain the observed discrepancy between increased tonic signalling and impaired learning. Although intriguing, this chaotic dopamine hypothesis lacks empirical support. In the current study, Pavlovian fear conditioning is used to test this hypothesis in healthy individuals with and without a family history of psychosis using simultaneous [11C]raclopride PET/fMRI. In 16 healthy individuals without a family history of psychosis, we first show that fear conditioning releases dopamine and link this release to BOLD responses. We then report that in 12 first-degree relatives of individuals with psychotic disorders, this adaptive dopamine release in the posterior caudate is lacking, despite no differences in behavioural learning. Furthermore, reduced dopamine release is associated with increased self-reported paranoid thinking, but not with anhedonia. These findings provide novel in vivo evidence supporting the chaotic dopamine hypothesis, suggesting that an adaptive, stimulus-driven dopamine release is lacking in psychotic disorders and may contribute to positive symptoms like paranoia.

Romantic love is a selective motivational state supporting pair bonding, yet its neural representation and relation to other affiliative-rewarding experiences remain unclear. Across eight fMRI studies (n=420) spanning naturalistic affiliative-reward, pharmacological and addiction-relevant experiments, we developed and evaluated multivariate whole-brain decoders of romantic love and friendship. Both signatures engaged mesocorticolimbic reward systems and the precuneus, yet were dissociable at the whole-brain level and in their recruitment of social-cognitive systems. The love signature generalized to reward on social media, was specific to positive valence, and did not track sweet-taste or monetary reward, indicating a distinct social-affiliative reward representation. Oxytocin selectively increased love - but not friendship - signature reactivity to the romantic partner. In an independent drug-cue-reactivity dataset, the love signature specifically identified heavy cannabis users. These findings establish a dissociable neurofunctional signature of romantic love in conserved bonding circuits that extend to digital affiliation and are co-opted in addiction.

BackgroundInflammation-associated depression is a subtype of major depressive disorder that is often resistant to conventional pharmacotherapies, which act in a regionally non-specific manner and therefore also produce unwanted side effects. Here we test GPR151, an orphan GPCR associated with inflammation and highly expressed in the habenula--a region linked to negative valence and depression--as a therapeutic target for inflammation-associated depression. MethodsWe integrated mouse and human habenular expression analyses with genetic loss-of-function and adult habenular re-expression approaches in mice. Gpr151 knockout mice and littermate controls were exposed to lipopolysaccharide (LPS) inflammatory challenge and assessed for stress coping and motivated behavior, body weight loss, and peripheral immune activation. To test whether adult habenular GPR151 expression is sufficient to restore inflammation-associated behavioral vulnerability, GPR151 was re-expressed in the habenula of knockout mice. ResultsGPR151 was exceptionally enriched in the habenula and showed conserved topographic organization and similar expression relationships with habenular marker genes in mice and humans. Following LPS challenge, male Gpr151 knockout mice showed reduced passive coping despite body weight loss and immune activation comparable to littermate controls. Adult habenular GPR151 re-expression increased LPS-induced amotivation in male knockout mice without increasing LPS-induced weight loss or immune activation. Female Gpr151 knockout mice also showed reduced passive coping after LPS challenge; however, habenular GPR151 re-expression was insufficient to increase LPS-induced amotivation in females. ConclusionsThese findings identify GPR151 as a conserved, regionally enriched regulator of behavioral sensitivity to inflammatory challenge and support GPR151 as a candidate therapeutic target for inflammation-associated depression.

N,N-dimethyltryptamine (DMT) is an endogenous psychedelic tryptamine that has recently emerged as a promising therapeutic candidate for acute ischemic stroke. Although DMT consistently reduces infarct size, attenuates neuroinflammation, and improves functional outcome in experimental stroke, the cellular and receptor mechanisms underlying these effects remain poorly understood. Primary rat microglial cultures were used to examine the direct anti-inflammatory effects of DMT following lipopolysaccharide (LPS)-induced activation. Microglial morphology, phagocytosis, and proteomic alterations were analyzed. Radioligand binding assays determined the affinity of DMT for microglial sigma-1 receptors (Sig-1Rs). Pharmacological inhibition of Sig-1Rs and serotonin (5-HT) receptors was performed to define receptor-specific mechanisms. Translational relevance was evaluated in acute mouse brain slices subjected to mild oxygen-glucose deprivation (mOGD) and anoxic episodes, where microglial activation, spreading depolarizations (SDs), and neuronal injury were assessed. DMT directly suppressed LPS-induced microglial activation, promoted a homeostatic morphology, and reduced phagocytic activity. Proteomic profiling demonstrated that DMT selectively reprogrammed inflammatory pathways by suppressing proteins involved in cytokine and chemokine signaling and oxidative stress while largely preserving arachidonic acid-prostaglandin synthesis. DMT bound microglial Sig-1Rs with micromolar affinity comparable to that reported in whole-brain preparations. Pharmacological inhibition revealed that DMT-induced morphological reprogramming required both Sig-1R and serotonergic signaling, whereas suppression of phagocytosis was largely independent of either receptor pathway. In acute brain slices, DMT attenuated microglial activation, reduced SD propagation and ischemic neuronal injury, and tissue-level neuroprotection depended on serotonergic signaling. DMT directly targets microglia and selectively remodels inflammatory states rather than broadly suppressing microglial activation. The receptor mechanisms underlying its actions are context dependent, with Sig-1R and serotonergic signaling contributing differentially according to the cellular response and experimental model. These findings provide mechanistic insight into the neuroprotective actions of DMT and support its ongoing clinical translation as a potential therapy for ischemic stroke.

Contextual fear memories become less specific as they age, modeling fear overgeneralization seen in post-traumatic stress disorder. Glucocorticoid receptor (GR) signaling in the dorsomedial prefrontal cortex (dmPFC) during the immediate post-learning period may govern both endocrine recovery from an aversive experience and the eventual specificity of the resulting memory, but this link remains untested. We infused vehicle or the GR antagonist mifepristone into the dmPFC of rats immediately after contextual fear conditioning, then measured corticosterone dynamics, fear expression at recent and remote time points, and c-Fos coactivation networks. Mifepristone accelerated corticosterone recovery without changing total hormone release, spared recent memory, and produced stronger, less context-specific freezing at the remote time point. This behavioral shift coincided with reorganization of the retrieval network from a salience-network-like to a default-mode-network-like configuration. These findings identify dmPFC glucocorticoid signaling as a mechanism constraining fear memory generalization as memories transition to a remote, cortically dependent state.

Serotonergic psychedelics (SP) are increasingly used in clinical research and naturalistic settings, but their psychotic-like side effects, including persisting perceptual abnormalities (PPAs), are poorly understood. Psychosis-associated hallucinations are associated with susceptibility to conditioned hallucinations and computationally-estimated overweighting of perceptual expectations, or priors. However, SPs are widely argued to reduce prior weighting. We surveyed 186 naturalistic SP users on prior SP use, SP-associated PPA history, and current PPAs. Participants completed the visual conditioned hallucinations (VCH) task, in which conditioning induces perception of absent stimuli. Behavioral data were used to fit parameters of a computational model to estimate latent states driving percepts and responses. Past and current PPAs were associated with younger age at first use and higher SP doses, lower visual thresholds, higher VCH rate and confidence, and reduced sensory discrimination. Among model parameters, however, only reduced decision precision tracked both measures and mediated the dose-PPA relationship; relative prior weighting rose equivocally, as expected when priors and sensory evidence gain precision together. SP-related PPAs may therefore arise from a noisy visual system biased toward detection, in which priors act as templates that convert sensory noise into expected percepts. These findings may point to a tractable model for how psychotic-like perception emerges.

Psilocybin produces rapid and lasting therapeutic effects, yet how 5-HT2A receptor activation reshapes brain-wide circuit dynamics during acute drug administration remains poorly understood. Using simultaneous multi-region Neuropixels recordings of 46,360 single units from 35 mice, together with scalp electroencephalography (EEG), pupillometry, and locomotion monitoring, we provide a brain-wide, single-unit and field-potential characterization of psilocybins acute effects, with pharmacological dissection using the 5-HT2A antagonist ketanserin. Psilocybin selectively reconfigured burst coding, rather than mean firing rate, across cortical, thalamic, and hippocampal circuits: burst firing decreased in hippocampal CA1-CA3 and was bidirectionally modulated in the thalamus, with the reticular nucleus bursting more and first-order geniculate nuclei bursting less. Critically, most of these burst effects were abolished by ketanserin, consistent with at least partial 5-HT2A receptor dependence. These data suggest that the psychedelic state is not simply a matter of how much neurons fire, but of how they fire, pointing to a region-specific, 5-HT2A-associated reconfiguration of burst coding that may underlie the acute phenomenology of the psilocybin experience.

Gathering information before committing to a choice is critical in real-world decision making, and biases thereof are hallmark features of psychiatric disorders. Here, we study the behavioural and neural mechanisms that guide information gathering and characterise several key cognitive constituents, including escalating urgency and systematically biased temporal weighting of information. Using fMRI, we identify an integrated information gathering signal in ventromedial and dorsomedial prefrontal cortices (dmPFC), signalling an overall likelihood for continued sampling of information. Teasing this signal apart, we find distinct neural circuits encoding separable information-gathering constituents: whilst an urgency signal primarily engaged locus coeruleus and dmPFC, accumulated evidence was represented in anterio-medial PFC, and evidence-strength prediction errors were computed in ventral striatum and dmPFC. These findings indicate that information gathering arises from functionally distinguishable prefrontal-subcortical computations that converge within medial prefrontal cortex, providing a mechanistic framework for understanding aberrant sampling in psychiatric conditions, including schizophrenia and obsessive-compulsive disorder.

The lateral habenula (LHb) encodes aversive states and negative affect, positioning it as a candidate region for the negative reinforcement that drives alcohol withdrawal. However, little is known about how chronic ethanol exposure affects LHb neuronal function and glial biology during withdrawal. Here, we used chronic intermittent ethanol (CIE) vapor exposure, a well-established model of alcohol dependence that reliably produces somatic and affective signs of withdrawal, to examine LHb physiology and astrocytic markers during acute withdrawal in male and female rats. Whole-cell and cell-attached recordings revealed that withdrawal reduced evoked and spontaneous firing in LHb neurons, with rebound firing following a crossover pattern between males and females. Despite these excitability changes, the overall distribution of firing phenotypes was unchanged, suggesting a shift in gain rather than a reorganization of cell types. Immunofluorescence revealed increased Sox9+ and GFAP labeling in the LHb during withdrawal at the same time point when electrophysiology experiments uncovered impaired astrocytic regulation of glutamate clearance. Together, these findings reveal that withdrawal from chronic ethanol exposure produces neuronal and glial adaptations in the LHb, pointing to impaired glutamate regulation as a candidate mechanism relevant to the negative affective state of alcohol withdrawal. These findings position the LHb as a potential node linking astrocyte-neuron dynamics to withdrawal symptoms and relapse vulnerability in alcohol use disorder.