Roy Dayne Mayfield

A significant minority of alcohol users develop alcohol addiction, characterized by continued use despite negative consequences, referred to as compulsive-like. We previously showed that vulnerability to compulsive-like alcohol use can be modeled in rats using punished alcohol self-administration and in male rats is mediated by PKCδ+ neurons in the central nucleus of the amygdala (CeA). Here, we used cell-type-specific transcriptomics to identify molecular mechanisms underlying individual differences in this behavior. Transcriptional changes were restricted to a limited number of CeA neuronal populations, including PKCδ+ neurons, where weighted Gene Co-expression Network Analysis identified an upregulated co-expression module in punishment-resistant rats with FGFR1 as a druggable upstream regulator. Selective silencing of FgfR1 in PKCδ+ neurons normalized elevated PKCδ+ expression, and reduced punishment-resistant alcohol self-administration. This effect was recapitulated by systemic administration of the FgfR1-antagonist PD173074. These findings identify distinct CeA circuits that promote addiction vulnerability, and position FGFR1 as potential therapeutic targets.

Alcohol use disorder (AUD) is a complex polygenic disease. Rodent models of alcohol dependence have been instrumental in modeling various aspects of dependence. Single-nucleus transcriptomics has enabled the profiling of cell-type-specific changes in gene expression in both human AUD and animal models. In this study, we identified shared dysregulated transcriptomic networks (TN), comprising gene co-expression modules and gene regulatory networks (GRNs) in a mouse model of alcohol dependence and individuals with AUD. Through cell-type-specific TN analysis, we identified translationally relevant, conserved dependence dysregulated molecular signatures. We identified conserved dependence-upregulated gene co-expression modules in astrocytes and oligodendrocytes, with hub genes Slc1a3 and Pde4b, respectively. These genes are linked to alcohol dependence mechanisms, such as glutamate signaling, a well-established target of alcohol’s effects, and PDE4, whose inhibition has been shown to reduce alcohol intake in preclinical and clinical studies. We then integrated publicly available human and mouse GRN data to identify upstream regulators of alcohol-dysregulated gene signatures in each cell type. This approach revealed a set of transcription factors (TFs), including Mef2a, Mef2c, Jund, Nr3c1, and Zeb1, that were upstream of most dysregulated genes in both the mouse and human datasets and have established relevance to addiction biology, representing promising targets for translational research. Collectively, these findings demonstrate the utility of cross-species, cell-type-specific network analysis for uncovering conserved molecular mechanisms in alcohol dependence. The identification of shared dysregulated networks, cell type homology, and upstream regulators provides a foundation for developing translationally relevant targeting strategies that can be tested in animal models.

Oligodendrocytes are a key cell type within the central nervous system (CNS) that generates the myelin sheath covering axons, enabling fast propagation of neuronal signals. Alcohol consumption is known to affect oligodendrocytes and white matter in the CNS. However, most studies have focused on foetal alcohol spectrum disorder and severe alcohol use disorder. Additionally, the impact of alcohol dosage on oligodendrocytes has not been previously investigated. In this study, we evaluated transcriptomic changes in C57BL6/J cultured mature oligodendrocytes following exposure to moderate and high concentrations of alcohol. We found that high concentrations of alcohol elicited gene expression changes across a wide range of biological pathways, including myelination, protein translation, integrin signalling, cell cycle regulation and inflammation. Further, our results demonstrate that transcriptomic changes are indeed dependent on alcohol concentration, with moderate and high concentrations of alcohol provoking distinct gene expression profiles. In conclusion, our study demonstrates that alcohol‐induced transcriptomic changes in oligodendrocytes are concentration‐dependent and may have critical downstream impacts on myelin production. Targeting alcohol‐induced changes in cell cycle regulation, integrin signalling, inflammation or protein translation regulation may uncover mechanisms for modulating myelin production or inhibition. Furthermore, gaining a deeper understanding of alcohol's effects on oligodendrocyte demyelination and remyelination could help uncover therapeutic pathways that can be utilized independently of alcohol to aid in remyelinating drug design.

Substance Use Disorders (SUDs) manifest as persistent drug-seeking behavior despite adverse consequences, with Alcohol Use Disorder (AUD) and Opioid Use Disorder (OUD) representing prevalent forms associated with significant mortality rates and economic burdens. The co-occurrence of AUD and OUD is common, necessitating a deeper comprehension of their intricate interactions. While the causal link between these disorders remains elusive, shared genetic factors are hypothesized. Leveraging public datasets, we employed genomic and transcriptomic analyses to explore conserved and distinct molecular pathways within the dorsolateral prefrontal cortex associated with AUD and OUD. Our findings unveil modest transcriptomic overlap at the gene level between the two disorders but substantial convergence on shared biological pathways. Notably, these pathways predominantly involve inflammatory processes, synaptic plasticity, and key intracellular signaling regulators. Integration of transcriptomic data with the latest genome-wide association studies (GWAS) for problematic alcohol use (PAU) and OUD not only corroborated our transcriptomic findings but also confirmed the limited shared heritability between the disorders. Overall, our study indicates that while alcohol and opioids induce diverse transcriptional alterations at the gene level, they converge on select biological pathways, offering promising avenues for novel therapeutic targets aimed at addressing both disorders simultaneously.

Excessive alcohol consumption is a leading cause of preventable death worldwide. To improve understanding of neurobiological mechanisms associated with alcohol use disorder (AUD) in humans, we compared gene expression data from deceased individuals with and without AUD across two addiction-relevant brain regions: the nucleus accumbens (NAc) and dorsolateral prefrontal cortex (DLPFC). Bulk RNA-seq data from NAc and DLPFC (N ≥50 with AUD, ≥46 non-AUD) were analyzed for differential gene expression using modified negative binomial regression adjusting for technical and biological covariates. The region-level results were meta-analyzed with those from an independent dataset (N_NAc = 28 AUD, 29 non-AUD; N_PFC = 66 AUD, 77 non-AUD). We further tested for heritability enrichment of AUD-related phenotypes, gene co-expression networks, gene ontology enrichment, and drug repurposing. We identified 176 differentially expressed genes (DEGs; 12 in both regions, 78 in NAc only, 86 in DLPFC only) for AUD in our new dataset. After meta-analyzing with published data, we identified 476 AUD DEGs (25 in both regions, 29 in NAc only, 422 in PFC only). Of these DEGs, 17 were significant when looked up in GWAS of problematic alcohol use or drinks per week. Gene co-expression analysis showed both concordant and unique gene networks across brain regions. We also identified 29 and 436 drug compounds that target DEGs from our meta-analysis in NAc and PFC, respectively. This study identified robust AUD-associated DEGs, contributing novel neurobiological insights into AUD and highlighting genes targeted by known drug compounds, generating opportunity for drug repurposing to treat AUD.

Currently available clinical treatments on alcohol use disorder (AUD) exhibit limited efficacy and new druggable targets are required. One promising approach to discover new molecular treatment targets involves the transcriptomic profiling of brain regions within the addiction neurocircuitry, utilizing animal models and postmortem brain tissue from deceased patients with AUD. Unfortunately, such studies suffer from large heterogeneity and small sample sizes. To address these limitations, we conducted a cross-species meta-analysis on transcriptome-wide data obtained from brain tissue of patients with AUD and animal models. We integrated 36 cross-species transcriptome-wide RNA-expression datasets with an alcohol-dependent phenotype vs. controls, following the PRISMA guidelines. In total, we meta-analyzed 964 samples – 502 samples from the prefrontal cortex (PFC), 282 nucleus accumbens (NAc) samples, and 180 from amygdala (AMY). The PFC had the highest number of differentially expressed genes (DEGs) across rodents, monkeys, and humans. Commonly dysregulated DEGs suggest conserved cross-species mechanisms for chronic alcohol consumption/AUD comprising MAPKs as well as STAT, IRF7, and TNF. Furthermore, we identified numerous unique gene sets that might contribute individually to these conserved mechanisms and also suggest novel molecular aspects of AUD. Validation of the transcriptomic alterations on the protein level revealed interesting targets for further investigation. Finally, we identified a combination of DEGs that are commonly regulated across different brain tissues as potential biomarkers for AUD. In summary, we provide a compendium of genes that are assessable via a shiny app, and describe signaling pathways, and physiological and cellular processes that are altered in AUD that require future studies for functional validation.

Alcohol use disorder (AUD) is a prevalent neuropsychiatric disorder that is a major global health concern, affecting millions of people worldwide. Past molecular studies of AUD used underpowered single cell analysis or bulk homogenates of postmortem brain tissue, which obscures gene expression changes in specific cell types. Here we performed single nuclei RNA-sequencing analysis of 73 post-mortem samples from individuals with AUD (N=36, N _nuclei = 248,873) and neurotypical controls (N=37, N _nuclei = 210,573) in both sexes across two institutional sites. We identified 32 clusters and found widespread cell type-specific transcriptomic changes across the cortex in AUD, particularly affecting glia. We found the greatest dysregulation in novel microglial and astrocytic subtypes that accounted for the majority of differential gene expression and co-expression modules linked to AUD. Analysis for cell type-specific enrichment of aggregate genetic risk for AUD identified subtypes of microglia and astrocytes as potential key players not only affected by but causally linked to the progression of AUD. These results highlight the importance of cell-type specific molecular changes in AUD and offer opportunities to identify novel targets for treatment.