Chronic Cocaine Use and White Matter Coherence: A Diffusion Tensor Imaging Study.

OBJECTIVE: Chronic substance use and its effects on brain function and structure has long been of interest to clinicians and researchers. Prior cross-sectional comparisons of diffusion tensor imaging (DTI) metrics have suggested deleterious effects of chronic substance use (i.e., cocaine use) on white matter coherence. However, it is unclear how these effects may replicate across geographic regions when examined with similar technologies. In this study, we sought to conduct a replication of previous work in this area and determine whether there are any patterns of persistent differences in white matter microstructure between individuals with a history of cocaine use disorder (CocUD, according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) and healthy controls. METHOD: A total of 46 participants (21 healthy controls, 25 chronic cocaine users) were recruited from the Richmond, Virginia metropolitan area. Information regarding past and current substance use was collected from all participants. Participants also completed structural and DTI scans. RESULTS: Consistent with previous DTI studies, significant differences were found between fractional anisotropy (FA) and axial diffusivity (AD) CocUD and controls, with CocUD showing lower FA and AD in the right inferior and superior longitudinal fasciculus, the genu, body, and splenium of the corpus callosum, and the anterior, posterior, and superior corona radiata, among several other regions. These differences were not significant for other diffusivity metrics. Lifetime alcohol consumption was greater in the CocUD group, but lifetime alcohol consumption did not show a significant linear relationship with any of the DTI metrics in within-group regression analyses. CONCLUSIONS: These data align with previously reported declines in white matter coherence in chronic cocaine users. However, it is less clear whether comorbid alcohol consumption results in an additive deleterious effect on white matter microstructure.

Adolescent intermittent ethanol exposure enhances adult stress effects in male rats.

Binge patterns of alcohol use, prevalent among adolescents, are associated with a higher probability of developing alcohol use disorders (AUD) and other psychiatric disorders, like anxiety and depression. Additionally, adverse life events strongly predict AUD and other psychiatric disorders. As such, the combined fields of stress and AUD have been well established, and animal models indicate that both binge-like alcohol exposure and stress exposure elevate anxiety-like behaviors. However, few have investigated the interaction of adolescent intermittent ethanol (AIE) and adult stressors. We hypothesized that AIE would increase vulnerability to restraint-induced stress (RS), manifested as increased anxiety-like behavior. After AIE exposure, in adulthood, animals were tested on forced swim (FST) and saccharin preference (SP) and then exposed to either RS (90 min/5 days) or home-cage control. Twenty-four hours after the last RS session, animals began testing on the elevated plus maze (EPM), and were re-tested on FST and SP. A separate group of animals were sacrificed in adulthood after AIE and RS, and brains were harvested for immunoblot analysis of dorsal and ventral hippocampus. Consistent with previous reports, AIE had no significant effect on closed arm time in the EPM (anxiety-like behavior). However, in male rats the interaction of AIE and adult RS increased time spent in the closed arms. No effect was observed among female animals. AIE and RS-specific alterations were found in glial and synaptic markers (GLT-1, FMRP and PSD-95) in male animals. These findings indicate AIE has sex-specific effects on both SP and the interaction of AIE and adult RS, which induces a propensity toward anxiety-like behavior in males. Also, AIE produces persistent hippocampal deficits that may interact with adult RS to cause increased anxiety-like behaviors. Understanding the mechanisms behind this AIE-induced increase in stress vulnerability may provide insight into treatment and prevention strategies for alcohol use disorders.

In vivo evaluation of a microtubule PET ligand, [11C]MPC-6827, in mice following chronic alcohol consumption.

BACKGROUND: Excessive alcohol consumption is a global health burden and requires a better understanding of its neurobiology. A lower density of brain microtubules is found in alcohol-related human brain disease postmortem and in rodent models of chronic alcohol consumption. Here, we report in vivo imaging studies of microtubules in brain using our recently reported Positron Emission Tomography (PET) tracer, [11C]MPC-6827, in chronic alcohol-consuming adult male C57BL/6 J mice and control mice. METHODS: In vivo PET imaging studies of [11C]MPC-6827 (3.7 ± 0.8 MBq) were performed in two groups of adult male mice: (1) water-consuming control mice (n = 4) and (2) mice that consumed 20% alcohol (w/v) for 4 months using the intermittent 2-bottle choice procedure that has been shown to lead to signs of alcohol dependence. Dynamic 63 min PET images were acquired using a microPET Inveon system (Siemens, Germany). PET images were reconstructed using the 3D-OSEM algorithm and analyzed using VivoQuant version 4 (Invicro, MA). Tracer uptake in ROIs that included whole brain, prefrontal cortex (PFC), liver and heart was measured and plotted as %ID/g over time (0-63 min) to generate time-activity curves (TACs). RESULTS: In general, a trend for lower binding of [11C]MPC-6827 in the whole brain and PFC of mice in the chronic alcohol group was found compared with control group. No group difference in radiotracer binding was found in the peripheral organs such as liver and heart. CONCLUSIONS: This pilot study indicates a trend of loss of microtubule binding in whole brain and prefrontal cortex of chronic alcohol administered mice brain compared to control mice, but no loss in heart or liver. These results indicate the potential of [11C]MPC-6827 as a PET ligand for further in vivo imaging investigations of AUD in human.

Alcohol's Impact on the Fetus.

BACKGROUND: Alcohol is a teratogen and prenatal exposure may adversely impact the developing fetus, increasing risk for negative outcomes, including Fetal Alcohol Spectrum Disorder (FASD). Global trends of increasing alcohol use among women of childbearing age due to economic development, changing gender roles, increased availability of alcohol, peer pressure and social acceptability of women's alcohol use may put an increasing number of pregnancies at risk for prenatal alcohol exposure (PAE). This risk has been exacerbated by the ongoing COVID-19 pandemic in some countries. METHOD: This literature review presents an overview on the epidemiology of alcohol use among childbearing age and pregnant women and FASD by World Health Organization regions; impact of PAE on fetal health, including FASD; associated comorbidities; and social outcomes. RESULTS/CONCLUSION: The impact of alcohol on fetal health and social outcomes later in life is enormous, placing a huge economic burden on countries. Prevention of prenatal alcohol exposure and early identification of affected individuals should be a global public health priority.

Exploring relationships between alcohol consumption, inflammation, and brain structure in a heavy drinking sample.

BACKGROUND: Chronic alcohol consumption is associated with structural brain changes and increased inflammatory signaling throughout the brain and body. Increased inflammation in the brain has been associated with structural damage. Recent studies have also shown that neurofilament light polypeptide (NfL) is released into the systemic circulation following neuronal damage. Although NfL has thus been proposed as a biomarker for neurodegenerative diseases, its connection to alcohol use disorder has not been explored. For this secondary data analysis, we proposed a conceptual model linking alcohol consumption, the pro-inflammatory cytokine IL-6, brain structure, and NfL in heavy drinking participants. METHODS: Of the 182 individuals enrolled in this study, 81 participants had usable data on gray matter (GM) thickness and 80 had usable data on white matter (WM) diffusivity. A subset of participants had NfL (n = 78) and IL-6 (n = 117) data. An estimate of GM thickness was extracted from middle frontal brain regions using FreeSurfer. Estimated mean WM diffusivity values were extracted from Tract Based Spatial Statistics. NfL and IL-6 were measured in blood. Regression models were used to test individual linkages in the conceptual model. Based on significant regression results, we created a simplified conceptual model, which we tested using path analysis. RESULTS: In regressions, negative relationships emerged between GM and both drinks per drinking day (DPDD) (p = 0.018) and NfL (p = 0.004). A positive relationship emerged between WM diffusivity and DPDD (p = 0.033). IL-6 was not significantly associated with alcohol use, GM or WM. The final path model demonstrated adequate fit to the data and showed significant, negative associations between DPDD and middle frontal gyrus (MFG) thickness, and between MFG thickness and NfL, but the association between DPDD and NfL was not significant. CONCLUSIONS: This is the first study to show that heavy drinking is associated with lower GM thickness and higher WM diffusivity and that lower GM thickness is associated with higher circulating NfL. The analyses also show that the effects of drinking do not involve the pro-inflammatory cytokine IL-6.

Low-Molecular-Weight Mimetic of BDNF Loop 2 Reduces Ethanol Consumption in Female Rats.

The study examined the effect of GTS-201, a low-molecular weight mimetic of brain-derived neurotrophic factor (BDNF) loop 2, on persistent alcohol craving in outbred male and female albino rats with ethanol preference score ~50% developed in the free choice paradigm between 10% ethanol and water over 24 weeks. Both single and subchronic (5 days) injections of GTS-201 in a daily dose of 5 µg/kg reduced alcohol deprivation effect in female, but not in male rats. The possibility of in vivo sex-dependent regulation of modeled alcohol craving with a low-molecular-weight dipeptide mimetic of BDNF loop 2 was demonstrated and sex-related differences in this effect were revealed.

Vesicular glutamate transporter 2-containing neurons of the centrally-projecting Edinger-Westphal nucleus regulate alcohol drinking and body temperature.

Previous studies in rodents have repeatedly demonstrated that the centrally-projecting Edinger-Westphal nucleus (EWcp) is highly sensitive to alcohol and is also involved in regulating alcohol intake and body temperature. Historically, the EWcp has been known as the main site of Urocortin 1 (Ucn1) expression, a corticotropin-releasing factor-related peptide, in the brain. However, the EWcp also contains other populations of neurons, including neurons that express the vesicular glutamate transporter 2 (Vglut2). Here we transduced the EWcp with adeno-associated viruses (AAVs) encoding Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) to test the role of the EWcp in alcohol drinking and in the regulation of body temperature. Activation of the EWcp with excitatory DREADDs inhibited alcohol intake in a 2-bottle choice procedure in male C57BL/6J mice, whereas inhibition of the EWcp with DREADDs had no effect. Surprisingly, analysis of DREADD expression indicated Ucn1-containing neurons of the EWcp did not express DREADDs. In contrast, AAVs transduced non-Ucn1-containing EWcp neurons. Subsequent experiments showed that the inhibitory effect of EWcp activation on alcohol intake was also present in male Ucn1 KO mice, suggesting that a Ucn1-devoid population of EWcp regulates alcohol intake. A final set of chemogenetic experiments showed that activation of Vglut2-expressing EWcp neurons inhibited alcohol intake and induced hypothermia in male and female mice. These studies expand on previous literature by indicating that a glutamatergic, Ucn1-devoid subpopulation of the EWcp regulates alcohol consumption and body temperature.

Effects of a Peripherally Restricted Hybrid Inhibitor of CB1 Receptors and iNOS on Alcohol Drinking Behavior and Alcohol-Induced Endotoxemia.

Alcohol consumption is associated with gut dysbiosis, increased intestinal permeability, endotoxemia, and a cascade that leads to persistent systemic inflammation, alcoholic liver disease, and other ailments. Craving for alcohol and its consequences depends, among other things, on the endocannabinoid system. We have analyzed the relative role of central vs. peripheral cannabinoid CB1 receptors (CB1R) using a "two-bottle" as well as a "drinking in the dark" paradigm in mice. The globally acting CB1R antagonist rimonabant and the non-brain penetrant CB1R antagonist JD5037 inhibited voluntary alcohol intake upon systemic but not upon intracerebroventricular administration in doses that elicited anxiogenic-like behavior and blocked CB1R-induced hypothermia and catalepsy. The peripherally restricted hybrid CB1R antagonist/iNOS inhibitor S-MRI-1867 was also effective in reducing alcohol consumption after oral gavage, while its R enantiomer (CB1R inactive/iNOS inhibitor) was not. The two MRI-1867 enantiomers were equally effective in inhibiting an alcohol-induced increase in portal blood endotoxin concentration that was caused by increased gut permeability. We conclude that (i) activation of peripheral CB1R plays a dominant role in promoting alcohol intake and (ii) the iNOS inhibitory function of MRI-1867 helps in mitigating the alcohol-induced increase in endotoxemia.

The paraventricular thalamus provides a polysynaptic brake on limbic CRF neurons to sex-dependently blunt binge alcohol drinking and avoidance behavior in mice.

Bed nucleus of the stria terminalis (BNST) neurons that synthesize corticotropin-releasing factor (CRF) drive binge alcohol drinking and anxiety. Here, we found that female C57BL/6J mice binge drink more than males and have greater basal BNSTCRF neuron excitability and synaptic excitation. We identified a dense VGLUT2 + synaptic input from the paraventricular thalamus (PVT) that releases glutamate directly onto BNSTCRF neurons but also engages a large BNST interneuron population to ultimately inhibit BNSTCRF neurons, and this polysynaptic PVTVGLUT2-BNSTCRF circuit is more robust in females than males. Chemogenetic inhibition of the PVTBNST projection promoted binge alcohol drinking only in female mice, while activation reduced avoidance behavior in both sexes. Lastly, repeated binge drinking produced a female-like phenotype in the male PVT-BNSTCRF excitatory synapse without altering the function of PVTBNST neurons per se. Our data describe a complex, feedforward inhibitory PVTVGLUT2-BNSTCRF circuit that is sex-dependent in its function, behavioral roles, and alcohol-induced plasticity.

Acetaldehyde exposure underlies functional defects in monocytes induced by excessive alcohol consumption.

Increased intestinal permeability and hepatic macrophage activation by endotoxins are involved in alcohol-induced liver injury pathogenesis. Long-term alcohol exposure conversely induces endotoxin immune tolerance; however, the precise mechanism and reversibility are unclear. Seventy-two alcohol-dependent patients with alcohol dehydrogenase-1B (ADH1B, rs1229984) and aldehyde dehydrogenase-2 (ALDH2, rs671) gene polymorphisms admitted for alcohol abstinence were enrolled. Blood and fecal samples were collected on admission and 4 weeks after alcohol cessation and were sequentially analyzed. Wild-type and ALDH2*2 transgenic mice were used to examine the effect of acetaldehyde exposure on liver immune responses. The productivity of inflammatory cytokines of peripheral CD14+ monocytes in response to LPS stimulation was significantly suppressed in alcohol dependent patients on admission relative to that in healthy controls, which was partially restored by alcohol abstinence with little impact on the gut microbiota composition. Notably, immune suppression was associated with ALDH2/ADH1B gene polymorphisms, and patients with a combination of ALDH2*1/*2 and ADH1B*2 genotypes, the most acetaldehyde-exposed group, demonstrated a deeply suppressed phenotype, suggesting a direct role of acetaldehyde. In vitro LPS and malondialdehyde-acetaldehyde adducted protein stimulation induced direct cytotoxicity on monocytes derived from healthy controls, and a second LPS stimulation suppressed the inflammatory cytokines production. Consistently, hepatic macrophages of ethanol-administered ALDH2*2 transgenic mice exhibited suppressed inflammatory cytokines production in response to LPS compared to that in wild-type mice, reinforcing the contribution of acetaldehyde to liver macrophage function. These results collectively provide new perspectives on the systemic influence of excessive alcohol consumption based on alcohol-metabolizing enzyme genetic polymorphisms.

Alcohol drinking during early adolescence activates microglial cells and increases frontolimbic Interleukin-1 beta and Toll-like receptor 4 gene expression, with heightened sensitivity in male rats compared to females.

Adolescent drinking is risky because neural circuits in the frontal lobes are undergoing maturational processes important for cognitive function and behavioral control in adulthood. Previous studies have shown that myelinated axons in the medial prefrontal cortex (mPFC) are particularly sensitive to alcohol drinking, especially in males. Pro-inflammatory mediators like toll-like receptor 4 (TLR4) and interleukin-1 beta (IL1b) have been implicated in alcohol induced-inflammation and demyelination; thus, herein we test the hypothesis that voluntary alcohol drinking early in adolescence elicits a pro-inflammatory state that is more pronounced in the brain of males compared to females. Adolescent male and female Wistar rats self-administered sweetened alcohol or sweetened water from postnatal days 28-42 and separate sets of brains were processed for 1) immunolabeling for ionized calcium-binding adapter molecule 1 to analyze microglial cell morphology, or 2) qPCR analysis of gene expression of pro-inflammatory mediators. Binge drinking alcohol activated microglia in the mPFC and hippocampus of both males and females, suggesting that voluntary alcohol exposure initiates an inflammatory response. Il1b mRNA was upregulated in the mPFC of both sexes. Conversely, Tlr4 mRNA levels were elevated after drinking only in males, which could explain more robust effects of alcohol on myelin in this region in developing males compared to females. Il1b mRNA changes were not observed in the hippocampus, but alcohol elevated Tlr4 mRNA in both sexes, highlighting regional specificity in inflammatory responses to alcohol. Overall, these findings give insight into potential mechanisms by which low-to-moderate voluntary alcohol intake impacts the developing brain. This article is part of the special Issue on 'Vulnerabilities to Substance Abuse'.

Brain-specific inhibition of mTORC1 eliminates side effects resulting from mTORC1 blockade in the periphery and reduces alcohol intake in mice.

Alcohol Use Disorder (AUD) affects a large portion of the population. Unfortunately, efficacious medications to treat the disease are limited. Studies in rodents suggest that mTORC1 plays a crucial role in mechanisms underlying phenotypes such as heavy alcohol intake, habit, and relapse. Thus, mTORC1 inhibitors, which are used in the clinic, are promising therapeutic agents to treat AUD. However, chronic inhibition of mTORC1 in the periphery produces undesirable side effects, which limit their potential use for the treatment of AUD. To overcome these limitations, we designed a binary drug strategy in which male mice were treated with the mTORC1 inhibitor RapaLink-1 together with a small molecule (RapaBlock) to protect mTORC1 activity in the periphery. We show that whereas RapaLink-1 administration blocked mTORC1 activation in the liver, RapaBlock abolished the inhibitory action of Rapalink-1. RapaBlock also prevented the adverse side effects produced by chronic inhibition of mTORC1. Importantly, co-administration of RapaLink-1 and RapaBlock inhibited alcohol-dependent mTORC1 activation in the nucleus accumbens and attenuated alcohol seeking and drinking.

A Novel Dual Drug Approach That Combines Ivermectin and Dihydromyricetin (DHM) to Reduce Alcohol Drinking and Preference in Mice.

Alcohol use disorder (AUD) affects over 18 million people in the US. Unfortunately, pharmacotherapies available for AUD have limited clinical success and are under prescribed. Previously, we established that avermectin compounds (ivermectin [IVM] and moxidectin) reduce alcohol (ethanol/EtOH) consumption in mice, but these effects are limited by P-glycoprotein (Pgp/ABCB1) efflux. The current study tested the hypothesis that dihydromyricetin (DHM), a natural product suggested to inhibit Pgp, will enhance IVM potency as measured by changes in EtOH consumption. Using a within-subjects study design and two-bottle choice study, we tested the combination of DHM (10 mg/kg; i.p.) and IVM (0.5-2.5 mg/kg; i.p.) on EtOH intake and preference in male and female C57BL/6J mice. We also conducted molecular modeling studies of DHM with the nucleotide-binding domain of human Pgp that identified key binding residues associated with Pgp inhibition. We found that DHM increased the potency of IVM in reducing EtOH consumption, resulting in significant effects at the 1.0 mg/kg dose. This combination supports our hypothesis that inhibiting Pgp improves the potency of IVM in reducing EtOH consumption. Collectively, we demonstrate the feasibility of this novel combinatorial approach in reducing EtOH consumption and illustrate the utility of DHM in a novel combinatorial approach.

Inducible nitric oxide synthase (iNOS) mediates ethanol-induced redox imbalance and upregulation of inflammatory cytokines in the kidney.

Overexpression of the inducible isoform of the enzyme nitric oxide synthase (iNOS) has been associated to pathological processes in the kidney. Ethanol consumption induces the renal expression of iNOS; however, the contribution of this enzyme to the deleterious effects of ethanol in the kidney remains elusive. We examined whether iNOS plays a role in the renal dysfunction and oxidative stress induced by ethanol consumption. With this purpose, male C57BL/6 wild-type (WT) or iNOS-deficient (iNOS-/-) mice were treated with ethanol (20% v/v) for 10 weeks. Treatment with ethanol increased the expression of Nox4 as well as the concentration of thiobarbituric acid reactive substances and the levels of tumor necrosis factor α in the renal cortex of WT but not iNOS-/- mice. Augmented serum levels of creatinine and increased systolic blood pressure were found in WT and iNOS-/- mice treated with ethanol. WT mice treated with ethanol showed increased production of reactive oxygen species and myeloperoxidase activity, but these responses were attenuated in iNOS-/- mice. We concluded that iNOS played a role in ethanol-induced oxidative stress and pro-inflammatory cytokine production in the kidney. These are mechanisms that may contribute to the renal toxicity induced by ethanol.

Ten seconds of my nights: Exploring methods to measure brightness, loudness and attendance and their associations with alcohol use from video clips.

INTRODUCTION: Most evidence on associations between alcohol use behaviors and the characteristics of its social and physical context is based on self-reports from study participants and, thus, only account for their subjective impressions of the situation. This study explores the feasibility of obtaining alternative measures of loudness, brightness, and attendance (number of people) using 10-second video clips of real-life drinking occasions rated by human annotators and computer algorithms, and explores the associations of these measures with participants' choice to drink alcohol or not. METHODS: Using a custom-built smartphone application, 215 16-25-year-olds documented characteristics of 2,380 weekend night drinking events using questionnaires and videos. Ratings of loudness, brightness, and attendance were obtained from three sources, namely in-situ participants' ratings, video-based annotator ratings, and video-based computer algorithm ratings. Bivariate statistics explored differences in ratings across sources. Multilevel logistic regressions assessed the associations of contextual characteristics with alcohol use. Finally, model fit indices and cross-validation were used to assess the ability of each set of contextual measures to predict participants' alcohol use. RESULTS: Raw ratings of brightness, loudness and attendance differed slightly across sources, but were all correlated (r = .21 to .82, all p < .001). Participants rated bars/pubs as being louder (Cohen's d = 0.50 [95%-CI: 0.07-0.92]), and annotators rated private places as darker (d = 1.21 [95%-CI: 0.99-1.43]) when alcohol was consumed than when alcohol was not consumed. Multilevel logistic regressions showed that drinking in private places was more likely in louder (ORparticipants = 1.74 [CI: 1.31-2.32]; ORannotators = 3.22 [CI: 2.06-5.03]; ORalgorithm = 2.62 [CI: 1.83-3.76]), more attended (ORparticipants = 1.10 [CI: 1.03-1.18]; ORalgorithm = 1.19 [CI: 1.07-1.32]) and darker (OR = 0.64 [CI: 0.44-0.94]) situations. In commercial venues, drinking was more likely in darker (ORparticipants = 0.67 [CI: 0.47-0.94]; ORannotators = 0.53 [CI: 0.33-0.85]; ORalgorithm = 0.58 [CI: 0.37-0.88]) and louder (ORparticipants = 1.40 [CI: 1.02-1.92]; ORalgorithm = 2.45 [CI: 1.25-4.80]) places. Higher inference accuracies were found for the models based on the annotators' ratings (80% to 84%) and the algorithms' ratings (76% to 86%) than on the participants' ratings (69% to 71%). CONCLUSIONS: Several contextual characteristics are associated with increased odds of drinking in private and commercial settings, and might serve as a basis for the development of prevention measures. Regarding assessment of contextual characteristics, annotators and algorithms might serve as appropriate substitutes of participants' in-situ impressions for correlational and regression analyses despite differences in raw ratings. Collecting contextual data by means of sensors or media files is recommended for future research.

Meta-analysis of grey matter changes and their behavioral characterization in patients with alcohol use disorder.

Alcohol Use Disorder (AUD) is associated with reductions in grey matter (GM) volume which can lead to changes in numerous brain functions. The results of previous studies on altered GM in AUD differ considerably in the regions identified. Three meta-analyses carried out between 2014 and 2017 yielded different results. The present study includes the considerable amount of newer research and delivers a state-of-the art meta-analysis in line with recently published guidelines. Additionally, we behaviorally characterized affected regions using fMRI metadata and identified related brain networks by determining their meta-analytic connectivity patterns. Twenty-seven studies with 1,045 AUD patients and 1,054 healthy controls were included in the analysis and analyzed by means of Anatomical Likelihood Estimation (ALE). GM alterations were identified in eight clusters covering different parts of the cingulate and medial frontal gyri, paracentral lobes, left post- and precentral gyri, left anterior and right posterior insulae and left superior frontal gyrus. The behavioral characterization associated these regions with specific cognitive, emotional, somatosensory and motor functions. Moreover, the clusters represent nodes within behaviorally relevant brain networks. Our results suggest that GM reduction in AUD could disrupt network communication responsible for the neurocognitive impairments associated with high chronic alcohol consumption.

Microglia depletion and alcohol: Transcriptome and behavioral profiles.

Alcohol abuse induces changes in microglia morphology and immune function, but whether microglia initiate or simply amplify the harmful effects of alcohol exposure is still a matter of debate. Here, we determine microglia function in acute and voluntary drinking behaviors using a colony-stimulating factor 1 receptor inhibitor (PLX5622). We show that microglia depletion does not alter the sedative or hypnotic effects of acute intoxication. Microglia depletion also does not change the escalation or maintenance of chronic voluntary alcohol consumption. Transcriptomic analysis revealed that although many immune genes have been implicated in alcohol abuse, downregulation of microglia genes does not necessitate changes in alcohol intake. Instead, microglia depletion and chronic alcohol result in compensatory upregulation of alcohol-responsive, reactive astrocyte genes, indicating astrocytes may play a role in regulation of these alcohol behaviors. Taken together, our behavioral and transcriptional data indicate that microglia are not the primary effector cell responsible for regulation of acute and voluntary alcohol behaviors. Because microglia depletion did not regulate acute or voluntary alcohol behaviors, we hypothesized that these doses were insufficient to activate microglia and recruit them to an effector phenotype. Therefore, we used a model of repeated immune activation using polyinosinic:polycytidylic acid (poly(I:C)) to activate microglia. Microglia depletion blocked poly(I:C)-induced escalations in alcohol intake, indicating microglia regulate drinking behaviors with sufficient immune activation. By testing the functional role of microglia in alcohol behaviors, we provide insight into when microglia are causal and when they are consequential for the transition from alcohol use to dependence.

Moderate alcohol consumption is associated with advanced fibrosis in non-alcoholic fatty liver disease and shows a synergistic effect with type 2 diabetes mellitus.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Whether moderate alcohol consumption plays a role for progression of NAFLD is disputed. Moreover, it is not known which tool is ideal for assessment of alcohol consumption in NAFLD. This study aimed to evaluate if moderate alcohol consumption assessed with different methods, including the biological marker phosphatidylethanol (PEth), is associated with advanced fibrosis in NAFLD. METHODS: We conducted a cross-sectional study of patients with biopsy-proven NAFLD. All participants were clinically evaluated with medical history, blood tests, and anthropometric measurements. Alcohol consumption was assessed using PEth in blood, the questionnaire AUDIT-C, and clinical interview. FINDINGS: 86 patients were included of which 17% had advanced fibrosis. All participants reported alcohol consumption < 140 g/week. Average weekly alcohol consumption was higher in the group with advanced fibrosis. Moderate alcohol consumption, independently of the method of assessment, was associated with increased probability of advanced fibrosis (adjusted OR 5.5-9.7, 95% CI 1.05-69.6). Patients with type 2 diabetes mellitus (T2DM) consuming moderate amounts of alcohol had a significantly higher rate of advanced fibrosis compared with those consuming low amounts (50.0-60.0% vs. 3.3-21.6%, p < 0.05). CONCLUSIONS: Moderate alcohol consumption, irrespective of assessment method (clinical interview, AUDIT-C, and PEth), was associated with advanced fibrosis. PEth in blood ≥ 50 ng/mL may be a biological marker indicating increased risk for advanced fibrosis in NAFLD. Patients with T2DM consuming moderate amounts of alcohol had the highest risk of advanced fibrosis, indicating a synergistic effect of insulin resistance and alcohol on the histopathological progression of NAFLD.

A Cohort Study Examining the Interaction of Alcohol Consumption and Obesity in Hepatic Steatosis and Mortality.

OBJECTIVE: To study the interaction of alcohol consumption with body mass index (BMI) in the development of hepatic steatosis and mortality. PARTICIPANTS AND METHODS: We conducted a retrospective cohort study of 18,506 participants without fatty liver disease or cirrhosis at enrollment in the Mayo Clinic Biobank from April 9, 2009, through March 31, 2016. Participants were classified by self-reported alcohol consumption status (nondrinkers, moderate drinkers [0 to 2 drinks per day], and heavy drinkers [>2 drinks per day]). The primary outcome of interest was the incidence of hepatic steatosis, identified by International Classification of Diseases, Ninth Revision code and confirmed with imaging. The secondary outcome of interest was all-cause mortality. Multivariate Cox regression analysis determined the impact of alcohol consumption stratified by BMI on outcomes compared with nondrinkers. RESULTS: The cohort (mean ± SD age, 55.8±16.9 years; 63.8% female; mean ± SD BMI, 28.8±6.1 kg/m2) of 18,506 participants included 3657 (19.8%) nondrinkers, 14,236 (76.9%) moderate drinkers, and 613 (3.3%) heavy drinkers at enrollment. After a median follow-up of 5.8 years (interquartile range, 3.8 to 7.2 years), 684 participants had development of hepatic steatosis and 968 died. In moderate drinkers, the risk of hepatic steatosis development was high in the obese group (adjusted hazard ratio [AHR], 1.31; 95% CI, 1.03 to 1.67), insignificant in the overweight group (AHR, 0.86; 95% CI, 0.58 to 1.26), and decreased in the normal-BMI group (AHR, 0.48; 95% CI, 0.26 to 0.90). Heavy drinkers had an increased risk of hepatic steatosis irrespective of BMI. Moderate alcohol use was associated with decreased mortality in the normal-weight (AHR, 0.44; 95% CI, 0.34 to 0.58) and overweight (AHR, 0.70; 95% CI, 0.56 to 0.88) groups but not in the obese group (AHR, 0.80; 95% CI, 0.64 to 1.00). CONCLUSION: In obese individuals, even moderate alcohol use is associated with the development of hepatic steatosis. Moderate alcohol consumption is associated with lower mortality in normal-BMI and overweight individuals but not in those who are obese.

A systematic review of interventions for reducing heavy episodic drinking in sub-Saharan African settings.

OBJECTIVE: Assess the effect of non-pharmacological alcohol interventions on reducing heavy episodic drinking (HED) outcomes in sub-Saharan Africa. METHODS: A systematic review of the available literature through August 19, 2020 was conducted. Randomized and non-randomized controlled trials testing non-pharmacological interventions on alcohol consumption in sub-Saharan Africa were eligible for inclusion. Eligible outcomes included measures of HED/binge drinking, and measures indicative of this pattern of drinking, such as high blood alcohol concentration or frequency of intoxication. Three authors extracted and reconciled relevant data and assessed risk of bias. The review protocol is available on PROSPERO (registration number: CRD42019094509). The Cochrane Handbook recommendations for the review of interventions and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines guided all methodology. RESULTS: Thirteen intervention trials were identified that met our inclusion criteria and measured change in HED. Studies were judged of moderate quality. A beneficial effect of non-pharmacological interventions on HED was reported in six studies, three of which were deemed clinically significant by the review authors; no statistically significant effects were identified in the other seven studies. Interventions achieving statistical and/or clinical significance had an intervention dose of two hours or greater, used an array of psychosocial approaches, including Motivational Interviewing integrated in Brief Intervention, cognitive behavioral therapy and integrated risk reduction interventions, and were delivered both individually and in groups. CONCLUSIONS: Evidence for the effectiveness of non-pharmacological interventions to reduce HED in sub-Saharan African settings was limited, demonstrating the need for more research. To strengthen the literature, future research should employ more rigorous study designs, improve consistency of HED measurement, test interventions developed specifically to address HED, and explore structural approaches to HED reduction.