Addiction Biology

Background: Substance use disorders (SUDs), including alcohol and drug dependence, and smoking, pose a public health threat with their high prevalence and comorbidity with other diseases, and contribution to mortality. SUDs are highly correlated, and their genetic background is shared to some degree. Objectives: We aimed to investigate the genetic associations of previously reported loci for a wide range of SUDs in an unstudied Ukrainian population. Methods: We collected data from 595 individuals (339 women, 253 men), including 321 participants from two rehab centres. Based on clinical review and questionnaire data we defined drug dependence, alcohol dependence, alcohol abuse, binge drinking, smoking, opiate, amphetamine, cannabis, and hallucinogen use, along with several intermediary alcohol use and smoking variables considering the amount of use and the level of dependence. We genotyped COMT-rs4680, ADH1B-ADH1C-rs1789891, and HTR2A-rs6313, and applied logistic and ordered logistic regression assuming an additive inheritance model, controlling for the recruitment group, other substance uses, age, and sex, in the association analyses. Results: We replicate (P<0.05) the associations at COMT-rs4680 with smoking status (OR[95% CI]=1.56[1.01-2.41], P=0.047) and heaviness (1.37[1.04-1.80], P=0.026), and at ADH1B-ADH1C-rs1789891 and HTR2A-rs6313 with alcohol dependence (1.69[1.03-2.76], P=0.038 and 0.66[0.47-0.92, P=0.016], respectively). Furthermore, we provide evidence for an association at HTR2A-rs6313 with hallucinogen use (0.58[0.35-0.98], P=0.040). Conclusion: In this study on multiple SUDs we shed light on the genetic background of SUDs in Ukrainians and provide further evidence that variation at COMT is mainly associated with smoking, at ADH1B-ADH1C with alcohol-related variables, whereas HTR2A is a more general SUD-associated locus.

IntroductionNeural cue reactivity is increasingly being investigated as a biomarker of treatment response and relapse prediction in addiction disorders. Whilst aberrant brain responses to salient cues (e.g. drugs) have been widely reported in addiction, it is unclear whether these brain responses persist during longer-term abstinence, how they compare between substance use disorder and obesity, and relate to potential differences in eating behaviours. As part of the Gut Hormones in ADDiction (GHADD) neuroimaging study, we investigated how salient cue reactivity to drugs or food, craving and eating behaviours compare in three clinical populations where alterations have been previously observed: abstinent nicotine use disorder (NUD) and alcohol use disorder (AUD), and obesity. MethodsThis study compared group differences in salient cue reactivity and eating behaviours between ex-smokers (n=25, ExS), adults with alcohol dependence who are abstinent (n=26, AAD), adults with obesity who were actively dieting (n=26, OB). Participants completed a high-energy food, preferred alcohol and cigarette functional magnetic resonance imaging (fMRI) cue reactivity task, along with eating behaviour questionnaires, appetite visual analogues scales and an ad libitum test meal. ResultsExS exhibited greater blood oxygen level dependent (BOLD) signal to high-energy food pictures in several reward processing regions in both whole brain and region of interest (ROI) analyses, compared with the OB and AAD groups, with no difference in their appeal rating. Compared with the OB group, ExS exhibited greater BOLD signal to cigarette pictures in the frontal gyrus, orbitofrontal cortex, frontal pole and insula, with no difference in their appeal rating. There were no group differences in preferred alcohol cue reactivity. The AAD group rated sweet taste as more pleasant, and consumed more calories from sweet dishes in the ad libitum meal than the OB and ExS groups. ConclusionsThe presence of heightened cue reactivity to high-energy foods in ex-smokers could contribute to post-quitting weight gain after smoking cessation. Neuroimaging findings were consistent with persistence of some salient drug cue reactivity, despite absence of craving, after medium term abstinence in ExS, but not in AAD. This study also adds to the body of evidence supporting a sweet taste preference endophenotype predisposing individuals to AUD. These changes in eating behaviour in NUD and AUD may provide targets for treatments to reduce substance misuse and facilitate abstinence.

Regular cannabis use has been associated with alterations in reward-related neural processes, yet findings remain inconsistent and the relationship between neural activity and behavioural performance is not fully understood. The present study aimed to characterise neural and behavioural correlates of reward processing in regular cannabis users (CU) compared with matched non-users (NU) using the Monetary Incentive Delay Task (MIDT). Firstly, we assessed behavioural performance through reaction times, accuracy and monetary earnings to determine whether potential neural alterations were reflected in task performance. Secondly, focusing on reward-related brain regions, we examined group differences in BOLD functional MRI activity during anticipation and outcome phases separately for monetary win and loss conditions. Finally, we explored the association between behavioural performance and neural activation. Our findings indicate that regular cannabis use is associated with altered engagement of key nodes within the mesocorticolimbic circuit during both anticipatory and outcome phases of reward processing, accompanied by impaired behavioural performance. Particularly, compared with NU, CU showed (I) lower striatal activity during anticipation of monetary win and higher ventral striatum and frontal pole activity during anticipation of monetary loss; (II) greater VTA activation during outcome of successful monetary win and loss avoidance and lower frontal pole activity during outcome of unsuccessful loss avoidance; (III) impaired behavioural performance, reflected in lower monetary rewards and a trend towards slower reaction times and reduced accuracy; (IV) disrupted brain-behaviour coupling. Results from this study may help inform future research on the neurobiological mechanisms underlying changes in reward function and the resultant behavioural consequences of cannabis use.

Preclinical evidence indicates that cocaine exerts acute and chronic effects on astrocyte functioning, which in turn modulate cocaine-related impacts on neural integrity and brain function. However, human evidence for astrocytic involvement in cocaine users (CU) remains limited. Glial fibrillary acidic protein (GFAP) is a marker of astrocyte activation with promising clinical utility in neurological conditions, yet its relevance in the addiction field is unclear. Hence, we investigated plasma GFAP levels in chronic CU (n=41) and cocaine-naive controls (HC; n=34) at baseline and after a 4-month follow-up. GFAP was assessed alongside plasma neurofilament light chain (NfL) levels, a marker of neuroaxonal injury previously associated with cocaine use in the same sample. Contrary to our hypothesis, we found no group differences in plasma GFAP concentrations between CU and HC. Neither cross-sectional nor longitudinal associations between GFAP levels and objective indices of cocaine use (derived from hair testing) were detected. However, exploratory analyses revealed higher plasma GFAP levels among CU with recent cocaine consumption (within the last 7 days), suggesting transient astrocytic responses following acute exposure. Additionally, GFAP and NfL were positively correlated across participants, supporting their functional association. Overall, these findings suggest that while GFAP might not be chronically elevated in CU, it may exhibit transient increases related to recent cocaine use. Further research is warranted to characterize the temporal dynamics and biological significance of these glial responses.

Studies have shown that substance use liability is associated with novelty seeking, anxiety-like behavior, and pain sensitivity. We examined whether common genetic variation in outbred Sprague-Dawley rats explained variation in behavioral measures from three assays with established links to substance use: locomotor response to a novel environment, elevated plus maze, and tail flick. We estimated single-nucleotide polymorphism heritability and performed genome-wide association analyses using permutation-derived significance thresholds (N=534-654 rats across traits). Heritability estimates ranged from 0.14-0.38 across eleven traits. Three independent loci were identified: chromosome 1 for elevated plus maze open-arm behavior (=0.05), chromosome 14 for elevated plus maze immobility (=0.10), and chromosome 17 for tail flick latency (=0.05). Candidate genes included Slc18a2, Gfra1, and Pdzd8 (chromosome 1); Rel and Bcl11a (chromosome 14); and Eci2 and Eci3 (chromosome 17). We compared these loci with our genome wide association study of a F2 intercross of selectively bred high- and low-responder rats, originally derived from Sprague-Dawleys, that model individual differences in externalizing and internalizing behavior. The current loci are distinct from the ones identified in the bred lines. This difference likely reflects selection history in the high- and low-responder F2s, which focused on facets of exploratory locomotion, while loci for anxiety and pain sensitivity traits were identified in the outbreds. This highlights the benefit of using both outbred and selectively bred rats to probe causal variants contributing to individual differences in substance use liability. The current outbred findings implicate monoaminergic signaling, transcriptional control, and lipid metabolism as testable mechanisms for addiction-relevant behaviors.

Alcohol use disorder (AUD) is a chronic relapsing condition with limited pharmacological treatments. Ethanol modulates neuronal excitability in part through activation of G-protein-gated inwardly rectifying potassium (GIRK/Kir3) channels, which dampen neuronal activity in reward- and stress-related circuits implicated in AUD pathophysiology. In this study, we investigated the therapeutic potential of targeting activation of GIRK channels in mouse models of ethanol intoxication. GiGA1 (G protein-independent GIRK activator type 1) is a selective activator of GIRK1/GIRK2 channels and has good brain bioavailability. Systemic GiGA1 administration prevented acquisition of ethanol-induced conditioned place preference (CPP) in both male and female mice. GiGA1 also significantly reduced voluntary ethanol intake and decreased blood alcohol concentrations, when administered to mice after they developed high preference and consumption of ethanol. Similarly, Baclofen, a GABAB receptor agonist that leads to activation of GIRK channels also decreased ethanol consumption. However, systemic Baclofen did not prevent acquisition of ethanol-dependent CPP, suggesting a broader efficacy of direct GIRK1/GIRK2 activation by GiGA1. Whole-brain c-Fos mapping as a proxy for neuronal activity revealed that GiGA1 blunted ethanol-induced neuronal activation in several AUD-relevant brain regions, including the central amygdala, paraventricular thalamus, paraventricular hypothalamus, and Edinger-Westphal nucleus. These findings demonstrate that pharmacological activation of GIRK channels modulates key neural circuits involved in ethanol reward and intake, supporting GiGA1 as a promising lead compound for targeted AUD therapy.

Background: Alcohol use disorder is associated with dysregulated glutamatergic signaling within mesocorticolimbic circuits that govern reinforcement and excessive ethanol intake. Group II metabotropic glutamate receptors (mGlu2/3) act primarily as presynaptic autoreceptors that regulate glutamate release. However, how voluntary alcohol intake alters mGlu2/3 expression within reward circuitry remains unclear. Methods and Results: We examined the effects of operant alcohol self-administration on mGlu2/3 protein expression and assessed the functional impact of group II receptor modulation on binge-like ethanol intake. Male C57BL/6J mice self-administered sweetened ethanol or sucrose under behaviorally matched conditions for 35 days. Immediately after the final session, tissue punches from the nucleus accumbens (NAc), amygdala, and prefrontal cortex were collected for Western blot analysis. Operant ethanol self-administration selectively reduced mGlu2/3 protein expression in the NAc, with no changes detected in the amygdala or prefrontal cortex. Both monomeric and dimeric mGlu2/3 protein levels were reduced, and a composite index revealed coordinated downregulation of receptor expression. In separate cohorts, systemic administration of the mGlu2/3 agonist LY379268 dose-dependently reduced binge-like ethanol intake in a limited-access home-cage drinking model, whereas positive allosteric modulation of mGlu2 receptors with LY487379 was ineffective. Conclusions: These results show that low-dose operant ethanol self-administration produces an ethanol- and region-specific reduction of mGlu2/3 protein expression in the NAc and that pharmacological activation of group II receptors, potentially involving mGlu3-specific receptors, is sufficient to suppress binge-like ethanol consumption. These data identify presynaptic mGlu2/3 dysregulation as a mechanism contributing to ethanol-related behaviors and support group II metabotropic glutamate receptors as therapeutic targets for alcohol use disorder.

Alcohol use disorder (AUD) affects over 28 million people in the U.S and is associated with neurobiological alterations, including in the basal ganglia. Within the basal ganglia, the caudate nucleus (caudate) and putamen are implicated in AUD due to their roles in ethanol reinforcement, with the caudate receiving inputs from cortico-associative areas and the putamen receiving inputs from somatosensory areas, supporting goal-directed and habitual behaviors respectively. These distinct behavioral roles are supported by dopamine signaling, including phasic dopamine, involved in assessing action-outcome associations, and tonic dopamine, which reflects ongoing dopaminergic tone that biases action initiation. Intrastriatal dopamine release is modulated by cholinergic interneurons via nicotinic acetylcholine receptors. Dysregulation of these mechanisms can contribute to the transition from occasional to habitual ethanol drinking. Here, we used in-vitro fast-scan cyclic voltammetry to measure dopamine signaling in male (n=6) and female (n=6) rhesus macaques following six months of ethanol self-administration. In putamen, ethanol increased tonic dopamine in both sexes, with females exhibiting greater release and faster dopamine uptake rates than males. In the caudate, ethanol self-administration enhanced dopamine uptake rates only in males. Phasic dopamine release was enhanced in caudate of both sexes but only putamen in males. nAChR blockade revealed that phasic dopamine release in males, but not females, was dependent on cholinergic modulation. These results demonstrate basal and sex-specific dopamine release and uptake are uniquely altered in rhesus macaque caudate and putamen in conjunction with chronic ethanol drinking.

Neuroimmune signaling is increased in postmortem brain tissue from individuals with alcohol use disorder (AUD), and growing evidence suggests that it contributes to persistent alcohol-related neuroadaptations. Interferon regulatory factor 7 (IRF7), a transcription factor downstream of endosomal Toll-like receptor signaling, is induced in alcohol-relevant brain regions and may contribute to escalated drinking. Here, we tested whether chronic intermittent ethanol (CIE) vapor exposure engages IRF7 signaling during subsequent alcohol self-administration and whether this is associated with altered molecular E/I balance in the aIC and altered functional E/I balance in aICnucleus accumbens projection neurons. Female Wistar rats (n=30) were trained to self-administer alcohol (15% v/v; FR2 vs inactive lever) during 30-minute sessions. After establishing baseline drinking, rats underwent 1-3 cycles of CIE, which increased alcohol self-administration at the 72 h post vapor test. This increase positively correlated with IRF7 levels in the anterior insular cortex (aIC) and nucleus accumbens, while molecular, and immunofluorescence showed that CIE shifted aIC excitatory/inhibitory (E/I) balance toward reduced excitation. Electrophysiological recordings further showed reduced functional E/I balance in aIC neurons projecting to the nucleus accumbens. Knockdown of IRF7 in the aIC attenuated CIE induced escalation of alcohol self-administration, supporting a role for insular IRF7 signaling in alcohol related neuroadaptations that promote escalated drinking.

Opioid use disorder (OUD) is a chronic, relapsing disease driven by the reinforcing properties of opioids and perpetuated by avoidance of the negative affective states associated with the absence of the drug. Most available OUD treatments directly engage the {micro}-opioid receptor and may induce side effects that can compromise their therapeutic efficacy, thus underscoring the need for novel therapeutic alternatives. Calcitonin gene-related peptide (CGRP) is produced by a small population of neurons in the parabrachial nucleus (PBN) that has been shown to modulate itch, pain, as well as appetitive behaviors. Using a cell-specific nuclear labeling approach coupled with RNA-sequencing, we generated a baseline transcriptome of CGRPPBN neurons and confirmed expression of multiple genes associated with behavioral responses to appetitive stimuli, as well as enrichment of the {micro}-opioid receptor, suggesting that CGRPPBN neuron function may be sensitive to the presence of opioids. Indeed, cFos immunostaining showed that CGRPPBN neuron activity increases during early morphine abstinence and reduces gradually over 48 hours. Given the inhibitory effects of opioids on CGRPPBN neuron activity, we next tested whether these neurons could regulate opioid reinforcement. Using a mouse model of morphine intravenous self-administration, we found that chemogenetic inhibition of CGRPPBN neurons significantly reduced the number of morphine rewards earned in both single-dose and dose-response tests but did not affect context-induced morphine seeking after 21 days of abstinence. These results suggest that CGRPPBN neurons are sensitive to opioid administration and can regulate appetitive behaviors such as morphine-taking. Considering that CGRP signaling is regulated by opioid administration, molecular targets that regulate CGRP neurotransmission without direct -opioid receptor engagement may therefore serve as novel therapeutic avenues for the treatment of OUD. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=195 SRC="FIGDIR/small/712659v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@1fb9c9borg.highwire.dtl.DTLVardef@1e6ba79org.highwire.dtl.DTLVardef@dc60f5org.highwire.dtl.DTLVardef@61adaf_HPS_FORMAT_FIGEXP M_FIG C_FIG

The Reln gene encodes the extracellular glycoprotein Reelin that regulates synaptic plasticity and activity-dependent gene expression with implications in several neuropsychiatric disorders, including substance use disorder. While reduced Reln expression alters responses to psychostimulants and cannabinoid, its role in opioid-related behaviors remains unknown. Here, we examined whether Reln haploinsufficiency modifies behavioral and molecular responses to the synthetic opioid fentanyl. Heterozygous Reeler (Reln+/-) mice and wild-type littermates were assessed using using complementary contingent and non-contingent models of fentanyl exposure, including multi-phase fentanyl intravenous self-administration paradigm, conditioned place preference paradigm, locomotor assay, and dorsal striatal immediate early gene expression. Reln haploinsufficiency did not alter acquisition, extinction, or cue-induced reinstatement during self-administration, indicating stable opioid reinforcement and relapse-like behavior. Progressive ratio testing revealed a sex-dependent effect in which male Reln+/- mice showed reduced motivation for fentanyl compared to male wild-type mice. In contrast, following passive fentanyl exposure, Reln+/- mice exhibited enhanced fentanyl-induced locomotion and increased Fos immunoreactivity in the dorsal striatum, while CPP remained unchanged. Together, these findings demonstrate that Reln haploinsufficiency does not substantially modify opioid reinforcement or cue-driven drug seeking but enhances acute pharmacological sensitivity to fentanyl. These results identify Reln as a modulatory factor in opioid-responsive neural circuits that preferentially influences acute drug-evoked neuronal activation rather than the associative learning processes underlying opioid reinforcement.

BackgroundIndividual vulnerability to addiction is driven by neuroadaptations within dopaminergic circuits. G protein-coupled receptor kinases (GRKs), specifically GRK2 and GRK3 regulate D2 receptor (D2R) signaling and trafficking, but their role in amphetamine (AMPH)-induced locomotor sensitization remains unclear. This study aimed to determine whether GRK2/3 inhibition alters locomotor sensitization and its associated molecular correlates across striatal regions. MethodsAdult rats (n = 39) were assigned to saline, acute AMPH, or repeated AMPH groups and received intraperitoneal administration of vehicle or the GRK2/3 inhibitor Cmpd101 (1.0 mg/kg intraperitoneally, i.p.). Locomotor activity was assessed under basal and injection conditions to evaluate sensitization. Protein levels of D2R, GRK2, and GRK5 were quantified across striatal regions using Western blot and analyzed with linear mixed models. ResultsRepeated AMPH exposure induced locomotor sensitization in a subset of animals, but Cmpd101 did not significantly modify locomotor activity or sensitization expression. At the molecular level, Cmpd101 had no effect on D2R levels and produced selective, region-dependent changes in GRK2 and GRK5. Notably, GRK2/3 inhibition altered the relationship between protein expression and locomotor sensitization in a region-specific manner, rather than inducing consistent changes in absolute protein levels. ConclusionsGRK2/3 inhibition by Cmpd101 produces region-specific molecular effects and reshapes protein-behavior relationships without significantly altering locomotor sensitization. These findings support a model in which GRKs act as context-dependent modulators of dopaminergic signaling rather than direct drivers of behavioral output.

Tobacco use disorder (TUD) remains a leading cause of preventable mortality, and existing pharmacotherapies yield 12-month abstinence rates below 30%. As cannabis legalization expands, approximately 18-22% of people who use tobacco report concurrent cannabis use, yet the impact of co-use on cessation outcomes and the therapeutic potential of endocannabinoid system (ECS) modulation remain unclear. We conducted a translational systematic review and meta-analysis following PRISMA 2020 guidelines, searching Ovid MEDLINE, Embase, APA PsycInfo, and Web of Science through January 2026 (PROSPERO: CRD420250652724). Three study categories were eligible: observational studies of cannabis co-use and cessation outcomes; preclinical studies of cannabinoid modulators on nicotine-related behaviors; and human experimental studies of ECS-targeted interventions. Of 4,869 records screened, 52 studies met inclusion criteria. Meta-analysis of 18 observational studies (N=229,630) revealed that cannabis use was associated with 35% lower odds of achieving tobacco smoking cessation (OR=0.65; 95% CI: 0.55-0.78; p<0.0001; I{superscript 2}=88.1%). Preclinical evidence (15 studies) demonstrated that CB1 receptor antagonists robustly reduced nicotine self-administration and reinstatement, while cannabidiol (CBD) attenuated both nicotine intake and withdrawal without affecting food reinforcement. Clinical translation of CB1 receptor inverse agonists failed due to psychiatric adverse effects, but CBD showed promise by reducing cigarette consumption by 40%, reversing attentional bias to smoking cues, and alleviating withdrawal severity. These findings distinguish naturalistic cannabis exposure from potentially beneficial targeted ECS modulation, and support CBD as a promising candidate for adequately powered tobacco cessation trials.

Excessive alcohol drinking is a leading cause of preventable death in the United States. High alcohol consumption and persistent drinking despite adverse events, also known as compulsive drinking, are key criteria that contribute to the development and progression of alcohol use disorder (AUD). There is a clear need to better understand the mechanisms that support these related but distinct behaviors. The serotonin (5-HT) system has been associated with alcohol consumption and risk of alcohol dependence, however given the complexity of this system, there remains much to discover regarding specific alcohol related phenotypes. The current study uses a combination of volitional home-cage drinking and operant conditioning to phenotype mice based on ethanol intake and persistence of alcohol drinking following quinine adulteration, a model to study compulsive drinking. Brain tissue of 10 regions known to be implicated in regulating executive function, reward, and stress was collected, and gene expression of serotonergic receptors, transporters, and enzymes was quantified. Three opioid receptors were included given their well-established roles in alcohol-related behaviors and interactions with the 5HT system. Region-specific gene expression patterns emerged, with serotonergic and opioid receptor expression differentially associated with alcohol drinking phenotype. 5-HT and opioid receptors displayed opposing directionality across regions, consistent with functional heterogeneity within the system. These findings identify region-specific molecular alterations following chronic alcohol that may contribute to individual differences in alcohol drinking phenotypes, highlighting candidate targets for biomarkers of increased alcohol use disorder susceptibility or as interventions aimed at preventing the progression of AUD.

Endocannabinoid (eCB) signaling is a key regulator of reward-related dopaminergic signaling, particularly in response to drugs of abuse, such as cocaine. To date, our understanding of this mechanism has primarily been limited to male subjects. Prior work establishes that female cocaine users have more adverse outcomes, and female rats show greater sensitivity to cannabinoid type 1 receptor (CB1R) regulation of cocaine self-administration. Therefore, we hypothesize that female rats exhibit enhanced eCB regulation of cocaine-evoked dopamine (DA). We used in vivo fiber photometry recording of the dopamine biosensor, dLight 1.3b, in the nucleus accumbens medial shell (NAcms) in response to cocaine in male and female rats. Rats were pretreated with cannabinoid-targeting drugs to investigate the effects of CB1R inactivation or augmentation of the eCB 2-AG on cocaine-evoked DA. Our results revealed that CB1R inactivation attenuates cocaine-evoked DA in male and female rats, but females showed enhanced sensitivity for CB1R regulation of cocaine-evoked DA. Cocaine-evoked DA was enhanced by augmenting 2-AG levels, and females again showed increased sensitivity to this manipulation. Finally, females show greater cocaine-evoked DA when in a non-estrous cycle compared to estrous, reinforcing that estrous cycle is a determinant of cocaine-evoked DA. These data indicate that females show enhanced eCB regulation of cocaine-evoked DA signaling, underscoring the importance of sex as a biological variable in our understanding of endocannabinoid regulation of drug reward. HighlightsO_LICB1R inactivation attenuates cocaine-evoked DA in NAcms, preferentially in females C_LIO_LI2-AG augmentation via MAGL inhibition enhances cocaine-evoked DA, with female bias C_LIO_LIEstrous phase modulates the dopamine response to a high dose of cocaine in females C_LIO_LIMale and female rats show similar baseline DA and locomotor responses to cocaine C_LI

Craving is a hallmark feature of substance use disorders (SUDs) and a major risk factor for relapse, yet reliable biomarkers that enable individual-level prediction remain scarce. Here, we applied connectome-based predictive modeling (CPM) to resting-state functional magnetic resonance imaging (fMRI) data in a transdiagnostic sample of individuals with cannabis, opioid, or tobacco use disorder (n = 78). Using CPM, we identified a distributed functional brain network that reliably predicted self-reported craving. Computational lesion analyses revealed key contributions from the right medial orbitofrontal cortex, right dorsal posterior cingulate cortex, and left lateral medial frontal gyrus. Importantly, the craving network generalized across two independent datasets. In alcohol-dependent patients (n = 41), the identified craving network, along with its positive and negative subnetworks, predicted distinct cognitive and motivational components of craving. In a second external dataset of smokers (n = 28), the craving network predicted both nicotine craving after abstinence as well as intra-individual changes in craving between sated and craving states. Together, these findings provide evidence for a robust, transdiagnostic craving signature in SUDs. Future work should assess the networks predictive utility for longitudinal outcomes such as relapse risk and treatment response.

Substance Use Disorders (SUDs) constitute a major and rising public health concern. In addition, there is a growing appreciation that different classes of addictive substances are likely to lead to qualitatively different types of SUDs requiring differing treatment and relapse prevention strategies to be most effectively managed. Biological temperament, particularly on the internalizing - externalizing axis, is well established to influence addiction susceptibility. Externalizing behavior has long been understood to predispose individuals to addiction through novelty-seeking, sensation-seeking and impulsivity, while internalizing behavior provides an alternate pathway into addiction via increased occurrence of comorbid disorders (anxiety, depression). Here, we utilize a selectively bred rat model of internalizing vs externalizing temperament (bred High Responders, representing genetically mediated externalizing behavior and bred Low Responders, representing internalizing behavior) to examine differences in the acquisition of self-administration of the prototypical psychostimulant cocaine and the prototypical opioid heroin (diacetylmorphine). We found that, as predicted, cocaine and heroin drove different patterns of acquisition in the two different bred lines of rats. Further, this was influenced by temperament in complex ways. Notably, in females the "telescoping effect" for opioid addiction-like behavior was primarily specific to externalizing temperament. These findings highlight the impact and interaction of many factors, including drug class, temperament, and sex, on the acquisition of drug-taking behavior. Additionally, these findings indicate that sex differences in addiction vulnerability may be influenced in part by biological temperament.

Maternal smoking during pregnancy is associated with adverse effects on offspring health through impaired placental structure and function. Nicotine and other tobacco-related compounds readily cross the placental barrier, disrupt metabolic pathways, and increase the risk of long-term developmental disorders in newborn. Here, placental metabolic alterations associated with maternal smoking exposure were examined with metabolomics. We used placental samples from the Kuopio Birth Cohort study from 23 nonsmoking controls pregnancies, 19 pregnancies with early smoking exposure (cotinine detected in first-trimester but not in at-term samples), and 13 pregnancies with continuous smoking-exposure (cotinine detected in both first-trimester and at-term samples). Differences in placental metabolomic profiles were seen between controls and both smoking-exposed groups. For example, increased activity of xenobiotic metabolism pathways showed as elevated CYP1A2-related metabolites, e.g., aminoamide local anesthetic metabolite detected in both smoking-exposure groups (p=0.0042 and 0.0019, respectively). Disruptions in amino acid metabolism were observed, e.g., reduced placental tryptophan levels (p=0.0209 and 0.0237). Placentas from women who quit smoking during showed markers of reduced oxidative stress, lower oxidized glutathione (p=0.0119) and higher ergothioneine (p=0.0426) levels. These findings indicate that many smoking-related effects on the placental metabolome persist beyond acute nicotine exposure, showing long-term biological effects of maternal smoking during pregnancy. Plain language summarySmoking during pregnancy can possibly change how the placenta functions, which also affects the newborns long-term health. In this study, we compared placentas from nonsmokers, women who quit during pregnancy, and those who kept smoking. Clear chemical differences were seen in the placentas of smoking exposed pregnant women. The main changes included lowered levels of tryptophan and glutathione, which are important for growth and protection from stress. These results show that smoking-related changes in the placenta can persist beyond active nicotine exposure.

BackgroundRates of binge drinking have converged significantly between the sexes over recent decades, driven by increased rates of alcohol misuse in women. However, understanding of fundamental circuitry and neurobiology driving alcohol use in females, or how this may differ from male subjects remains underexplored. MethodsWe quantified c-Fos expression across 40 brain regions in alcohol naive, alcohol anticipating and binge drinking male and female mice. In vivo fiber photometry examined sex differences in basolateral amygdala (BLA) activity changes to alcohol intake. Chemogenetic BLA inhibition investigated a functional role in binge drinking. We then assessed sex differences in BLA efferent projection activation following binge drinking. Finally, we functionally interrogated the BLA to nucleus accumbens core (AcbC) projection in binge drinking. ResultsBinge drinking reduced network modularity (number of communities with similar activation patterns) in both sexes relative to alcohol naive and anticipating same-sex counterparts. Female binge drinking mice had increased BLA c-Fos expression compared to female naive and male binge drinking counterparts. In vivo fiber photometry revealed greater and more prolonged BLA responsivity at the onset of alcohol intake in females. Global BLA inhibition reduced reward intake in both sexes. However, the BLA to AcbC projection was preferentially activated in female binge drinking mice, and inhibition of this pathway reduced binge alcohol intake exclusively in females. ConclusionsWe identified sex differences in the neural circuits engaged in binge drinking, highlighting the BLA to AcbC projection may in part underpin sex differences in alcohol misuse. This provides further evidence of distinct neurobiological drivers of alcohol-related behaviors between the sexes.

BackgroundPersistent automatic approach tendencies toward alcohol cues that resist goal-directed control are a key feature of harmful alcohol use, yet the causal neural mechanisms underlying this imbalance remain poorly understood. Converging evidence implicates the frontoparietal network (FPN) in actively regulating alcohol approach-avoidance behavior, but whether its constituent nodes make dissociable causal contributions has not been established. MethodsIn a within-subject, active-sham counterbalanced design, inhibitory continuous theta burst stimulation (cTBS) was applied to right dorsolateral prefrontal cortex (rDLPFC) and right posterior parietal cortex (rPPC) in separate groups of non-clinical alcohol users (rDLPFC: n = 29; rPPC: n = 28), followed by an Alcohol Approach-Avoidance Task. ResultsActive rDLPFC cTBS selectively slowed down alcohol push responses, whereas rPPC suppression produced a bidirectional action-specific shift in response to alcohol cues, where pull responses accelerated, and push slowed simultaneously. Suppression of either node shifted automatic tendencies toward greater alcohol approach through mechanistically distinct routes. ConclusionThese dissociable profiles indicate that rDLPFC is causally necessary for effortful top-down avoidance control, while rPPC supports the priority-based selection of alcohol cue-driven actions. These findings provide the first node-specific causal evidence for functional specialization within the FPN in the context of automatic tendencies towards alcohol. Alcohol avoidance emerges as an active, prefrontal-dependent process, whereas priority-based regulation emerges as a parietal-dependent process, together indicating rDLPFC and rPPC as mechanistically independent targets for intervention in maladaptive alcohol approach behavior.