The ability of environmental cues to trigger alcohol-seeking behaviours is thought to facilitate problematic alcohol use. Individuals' tendency to attribute incentive salience to cues may increase the risk of addiction. We sought to study the relationship between incentive salience and alcohol addiction using non-preferring rats to model the heterogeneity of human alcohol consumption, investigating both males and females. Adult rats were subjected to the alcohol deprivation effect (ADE) paradigm, where they were given voluntary access to different alcohol solutions with repeated interruptions by deprivation and reintroduction phases over a protracted period (five Alcohol Deprivation Cycles). Before each Alcohol Deprivation Cycle, rats were tested in the Pavlovian Conditioned Approach (PCA) paradigm, which quantifies the individual salience toward a conditional cue and the reward, thus allowing us to trace the process of attributing incentive salience to reward cues. During the final Alcohol Deprivation Cycle (ADE5), animals were tested for compulsive-like behaviour using quinine taste adulteration. We investigated sex differences in drinking behaviour and PCA performance. We observed thatb females drank significantly more alcohol than males and displayed more sign-tracking (ST) behaviour in the PCA, whereas males showed goal-tracking (GT) behaviour. Furthermore, we found that high drinkers exhibited more ST behaviour. The initial PCA phenotype was correlated with later alcohol consumption. Our findings indicate a complex relationship between incentive salience and alcohol addiction and emphasize the importance of considering both sexes in preclinical research.

The ventromedial prefrontal cortex (VMPFC), located along the medial aspect of the frontal area, plays a critical role in regulating arousal/emotions. Its intricate connections with subcortical structures, including the striatum and amygdala, highlight the VMPFC's importance in the neurocircuitry of addiction. Due to these features, the VMPFC is considered a promising target for transcranial magnetic stimulation (TMS) in substance use disorders (SUD). By the end of 2023, all 21 studies targeting VMPFC for SUD used anatomical landmarks (e.g., Fp1/Fp2 in the EEG system) to define coil location with a fixed orientation. Nevertheless, one-size-fits-all TMS over VMPFC has yielded variable outcomes. Here, we suggested a pipeline based on a tailored TMS targeting framework aimed at optimally modulating the VMPFC-amygdala circuit on an individual basis. We collected MRI data from 60 participants with methamphetamine use disorders (MUDs). We examined the variability in TMS target location based on task-based functional connectivity between VMPFC and amygdala using psychophysiological interaction (PPI) analysis. Electric fields (EF) were calculated for fixed vs. optimized location (Fp1/Fp2 vs. individualized maximal PPI), orientation (AF7/AF8 vs. optimized algorithm) and intensity (constant vs. adjusted) to maximize target engagement. In our pipeline, the left medial amygdala, identified as the brain region with the highest (0.31 ±0.29) fMRI drug cue reactivity, was selected as the subcortical seed region. The voxel with the most positive amygdala-VMPFC PPI connectivity in each participant was considered the individualized TMS target (MNI-coordinates: [12.6, 64.23, -0.8] ± [13.64, 3.50, 11.01]). This individualized VMPFC-amygdala connectivity significantly correlated with VAS craving after cue exposure (R = 0.27, p = 0.03). Coil orientation was optimized to increase EF strength over the targeted circuit (0.99 ±0.21 V/m vs. the fixed approach: Fp1: 0.56 ±0.22 and Fp2: 0.78 ±0.25 V/m) and TMS intensity was harmonized across the population. This study highlights the potential of an individualized VMPFC targeting framework to enhance treatment outcomes for addiction, specifically modulating the personalized VMPFC-amygdala circuit.

Morphine dependence or addiction is a serious global public health and social problem, and traditional treatments are very limited. Deep brain stimulation (DBS) has emerged as a new potential treatment for drug addiction. Repeated use of morphine leads to neuroadaptive and molecular changes in the addiction-related brain regions. We have previously performed isobaric tags for relative and absolute quantitation (iTRAQ) labelling coupled with 2D-LC MS/MS in anterior insular samples from rats treated with saline control, morphine or morphine plus DBS, and the identified expression of eight proteins are altered by morphine and reversed by high-frequency DBS (HF-DBS). In this study, we analysed the proteomic data in more details. A total of 5575 proteins were identified. Relative to the saline group, the morphine group showed 14 down-regulated and three up-regulated proteins. There were 118 proteins increased and 87 proteins decreased between DBS implanted animals and morphine group. Several differentially expressed proteins were verified with parallel reaction monitoring (PRM) assay. Based on Gene Ontology enrichment an KEGG pathway analyses, the majority of these differentially expressed proteins (DEPs) were involved in protein metabolic process, G-protein coupled receptor signalling pathway, calcium-mediated signalling, neurotransmitter transport, dopaminergic synapse and mTOR signalling pathway. These data offer a comprehensive understanding of the proteomic changes associated with morphine addiction and DBS therapy in addicted animal models, which is important for the development of DBS interventions for drug addiction.

The early initiation of binge-drinking and biological sex are critical risk factors for the development of affective disturbances and cognitive decline, as well as neurodegenerative diseases including Alzheimer's disease. Further, a history of excessive alcohol consumption alters normal age-related changes in the pattern of protein expression in the brain, which may relate to an acceleration of cognitive decline. Here, we aimed to disentangle the interrelation between a history of binge-drinking during adolescence, biological sex and normal aging on the manifestation of negative affect, cognitive decline and associated biochemical pathology. To this end, adolescent male and female C57BL/6J mice (PND 28-29) underwent 30 days of alcohol binge-drinking using a modified drinking-in-the-dark (DID) paradigm. Then, mice were assayed for negative affect, sensorimotor gating and cognition at three developmental stages during adulthood-mature adulthood (6months), pre-middle age (9months) and middle age (12 months). Behavioural testing was then followed by immunoblotting to index the protein expression of glutamate receptors, neuropathological markers [Tau, p (Thr217)-Tau, p (Ser396)-Tau, BACE, APP, Aβ], as well as ERK activation within the entorhinal cortex, prefrontal cortex and amygdala. Across this age span, we detected only a few age-related changes in our measures of negative affect or spatial learning/memory in the Morris water maze and all of these changes were sex-specific. Prior adolescent binge-drinking impaired behaviour only during reversal learning in 9-month-old females and during radial arm maze testing in 12-month-old females. In contrast to behaviour, we detected a large number of protein changes related to prior binge-drinking history, several of which manifested as early as 6months of age, with the prefrontal cortex particularly affected at this earlier age. While 6-month-old mice exhibited relatively few alcohol-related protein changes within the entorhinal cortex and amygdala, the number of alcohol-related protein changes within the entorhinal cortex increased with age, while the 12-month-old mice exhibited the largest number of protein changes within the amygdala. Approximately a third of the alcohol-related protein changes were sex-selective. Taken together, the results of our longitudinal study using a murine model of binge-drinking indicate that a prior history of heavy alcohol consumption, beginning in adolescence, is sufficient to induce what we presume to be latent changes in protein indices of cellular activity, glutamate transmission and neuropathology within key brain regions governing cognition, executive function and emotion that appear to precede the onset of robust behavioural signs of dysregulated affect and cognitive impairment.

The human brain consists of functionally segregated networks, characterized by strong connections among regions belonging to the same network and weak connections between those of different networks. Alcohol use disorder (AUD) is associated with premature brain aging and neurocognitive impairments. Given the link between decreased brain network segregation and age-related cognitive decline, we hypothesized lower brain segregation in patients with AUD than healthy controls (HCs). Thirty AUD patients (9 females, 21 males) and 61 HCs (35 females, 26 males) underwent resting-state functional MRI (rs-fMRI), whose data were processed to assess segregation within the brain sensorimotor and association networks. We found that, compared to HCs, AUD patients had significantly lower segregation in both brain networks as well as poorer performance on a spatial working memory task. In the HC group, brain network segregation correlated negatively with age and positively with spatial working memory. Our findings suggest reduced brain network segregation in individuals with AUD that may contribute to cognitive impairment and is consistent with premature brain aging in this population.

Pain and alcohol use disorder (AUD) frequently co-occur, but the underlying neurobiology is not well-understood. Although many studies have reported disruptions in stress and reward cue-elicited neural reactivity and heightened alcohol craving in individuals with AUD, little is known about these constructs among patients who experience pain. Here, individuals with pain (Pain+, n= 31) and without pain (Pain-, n= 37) completed a well-validated functional magnetic resonance imaging (fMRI) paradigm involving stress (S), alcohol (A) and neutral (N) cue exposure with repeated alcohol craving assessments. Using whole-brain, voxel-based analyses (p<0.001, whole-brain cluster correction at α< .05), the Pain+ versus Pain- group evidenced greater dorsal anterior cingulate cortex and left amygdala hyperactivation during N, but hypoactivation during the S-N contrast. Additionally, Pain+ exhibited blunted right anterior insular cortex (AIC) during S-N and blunted anteromedial thalamus and left AIC with hyperactive orbitofrontal cortex (OFC) during A-N. Exploratory analyses further revealed that individuals with pain and AUD (n= 17) relative to pain alone (n= 14) showed hyperactive bilateral AIC and hypoactive right dorsal caudate during A-N. Alcohol cue-induced craving, significantly higher in Pain+ (p=0.03), correlated with blunted right AIC and OFC responses during A-N. In sum, these results provide first evidence of heightened alcohol cue-elicited craving and disrupted stress- and alcohol cue-reactivity within corticostriatal-limbic regions implicated in negative affect and preoccupation/anticipation stages of AUD in those with pain and with comorbid pain and AUD. Future investigations of pain-AUD interaction are needed that include systematic pain assessment and longitudinal designs with larger sample sizes.