Animal models of binge drinking, current challenges to improve face validity

Exploring the effects of adolescent social isolation stress on the serotonin system and ethanol-motivated behaviors

RATIONALE

Alcohol is one of the most frequently used drugs of abuse and has a major impact on human health worldwide. People assigned female at birth and those with adverse childhood experiences are stress-vulnerable and more likely to report drinking as a means of "self-medication." Prior studies in our laboratory showed that adolescent social isolation stress (SIS) increases vulnerability to ethanol (EtOH) intake and consumption despite negative consequences in female rats.

OBJECTIVES

Here, we explored modulation of the dorsal raphe nucleus (DRN)-serotonin (5-HT) system, a sexually dimorphic neurotransmitter system involved in stress-reward interactions, to determine its contribution to EtOH-motivated behaviors in rats that have undergone SIS.

RESULTS

We employed electrophysiological and functional neuroanatomy strategies to show that both SIS and EtOH exposure induce persistent hypofunction of the DRN 5-HT system, particularly in females. Chemogenetic activation of DRN 5-HT neurons attenuated reward value for both EtOH and sucrose and elevated punished responding for EtOH in a stress-dependent manner.

CONCLUSIONS

Our results highlight an inverse relationship between EtOH consumption and the 5-HT system, the sex- and stress-dependent nature of this relationship, and a connection between DRN 5-HT signaling and acute responding to rewards and punishment. These data support the DRN 5-HT system as a potential target to treat aberrant alcohol consumption and drinking despite negative consequences in stress-vulnerable populations.

Global scientific research landscape on binge drinking: a comprehensive bibliometric and visualization analysis of trends, collaborations, and future directions

BACKGROUND

Binge drinking constitutes a significant public health concern. Defined as the consumption of five or more alcoholic beverages on a single occasion, binge drinking leads to acute cognitive and motor impairments and is associated with a multitude of detrimental health consequences. Therefore, the aim of this study was to analyse globally published peer-reviewed literature on binge drinking.

METHODS

A thorough search of the Scopus database was conducted to gather all the relevant research. Keywords related to binge drinking were used to locate a wide range of studies. Specific criteria were subsequently applied to narrow the results, ensuring the inclusion of only the most relevant articles. This process yielded a collection of 2,763 research papers. Finally, a software program called VOSviewer was utilized to analyse and visualize the connections between these studies.

RESULTS

A bibliometric analysis was performed to investigate trends in binge drinking research literature published between 1980 and 2024. The findings revealed a significant increase in publications (R²=0.916; p < 0.001), with a peak in 2018 (191 articles). The majority (89.65%, n = 2,477) were research articles, followed by review articles (4.74%, n = 131). Authors from 139 countries contributed to binge-drinking research, with the USA (n = 1,550; 56.1%) and the UK (n = 216; 7.82%) leading in the volume of publications. The National Institute on Alcohol Abuse and Alcoholism (n = 65; 2.35%) and the University of North Carolina at Chapel Hill (n = 63; 2.28%) emerged as the main institutional contributors. The National Institute on Alcohol Abuse and Alcoholism in the United States was the main funding source, supporting 599 articles (21.68%), followed by the National Institutes of Health in the United States, with 544 articles (19.69%). In particular, the post-2016 period witnessed a shift in research themes toward mechanistic investigations alongside studies on societal interventions, reflecting a growing focus on mitigating the broader social impact of binge drinking.

CONCLUSIONS

This study is the first comprehensive analysis of trends in binge drinking research. Over the past decade, binge drinking has increased dramatically, led by the United States, the UK, and Spain. Initially, focused on social and cultural factors, research shifted after 2016 to mechanistic and animal models, shaping future research directions and strategies.

Effect of prenatal alcohol consumption on dental enamel formation in offspring-An animal study protocol

BACKGROUND

The etiology of developmental defects of enamel (DDE) remains incompletely understood. Prenatal alcohol exposure has been proposed as a potential risk factor for DDE. Animal studies suggest that in utero ethanol exposure can disrupt ameloblast function, leading to enamel abnormalities. This study aims to: (1) Assess the impact of prenatal alcohol consumption on the clinical and structural properties of dental enamel in offspring; and (2) Investigate the underlying mechanisms of these alterations through histological and molecular analyses. Pregnant Wistar rats will be assigned to two groups: one exposed to ethanol and a control group with no alcohol exposure. Ethanol exposure will follow a binge drinking model, with rats receiving 3 g/kg of ethanol (30% w/v) for 3 consecutive days, followed by 4 days of rest each week. This regimen will begin one week prior to conception and continue throughout pregnancy. The incisors and molars of offspring will be evaluated on the 10th (n = 22 per group) and 28th (n = 22 per group) days of life. Visible enamel changes will be documented through photographs. Enamel volume, thickness, and density will be assessed using micro-CT imaging. Mechanical properties will be evaluated using the Knoop microhardness test, while chemical composition will be analyzed through Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX) and Raman spectroscopy, respectively. The area of the organic enamel matrix will be quantified in histological sections. Genes Amelx, Enam, Ambn, Mmp2, Mmp9, Mmp20, Klk4, Cldn3, Cldn16, and Cldn19 will be evaluated in ameloblasts using real-time RT-PCR and protein synthesis will be confirmed by immunohistochemistry. Gelatinolytic activity in the ameloblast layer will be assessed by in situ zymography.

Differential effects of chronic and intermittent administration of taurine on alcohol binge drinking in male rats

Episodic consumption of high doses of alcohol in a short period (binge drinking - BD) among adolescents is known to be harmful to their brain development. Chronic use of taurine increases voluntary alcohol consumption and shows an anxiolytic-like effect in rats. In this study, we evaluated the differential effects of chronic and intermittent taurine administration on alcohol consumption and behavioral changes in adolescent and young adult rats subjected to the BD model. Male Wistar rats (35 days old) were divided into 4 groups for daily intraperitoneal administration of saline (SAL); taurine, 100 mg/kg (TAU); taurine on BD days and saline on intervals (TAU/SAL); and saline on BD days and taurine on intervals (SAL/TAU). They were exposed to 4 cycles of BD, with free access to alcoholic solution (20 % w/v), for 2 h, 3 days per week. At the end of the 3rd cycle, anxiety-like behaviors were assessed using the light-dark task. After euthanasia, plasma and prefrontal cortex samples were collected to measure corticosterone and BDNF levels, respectively. Chronic taurine treatment did not alter alcohol consumption in rats, whereas intermittent administration increased alcohol intake after 4 BD exposures (TAU/SAL: +19.4 % and SAL/TAU: +21.6 %). No anxiolytic-like effects were found by taurine administration, nor were there changes in serum corticosterone or BDNF levels in the frontal cortex of young adult rats. Intermittent taurine, but not chronic treatment, increased alcohol intake among rats after the second week of exposure. The translation of these results to humans is concerning since the combination of alcohol and drinks containing taurine is common among adolescent and young adult individuals.

Animal models for studying therapeutic targets and treatments for alcohol use disorder

Over the decades, preclinical models have been developed and refined to investigate the rewarding effects of addictive substances and the neurobiological underpinnings of alcohol and other drug use disorders. This chapter delves into the methodological foundations, advantages, and limitations of leading animal models used to study alcohol use disorders (AUDs). Some models focus on the early stages of alcohol use and abuse. For instance, conditioned place preference assesses associative learning between a specific context and the effects of the drug, while locomotor sensitization measures increased locomotor activity following repeated drug exposure. In contrast, contingent models such as operant and non-operant alcohol self-administration protocols gauge voluntary intake, preference, motivation, and seeking behavior for alcohol solutions among experimental subjects. Additionally, we discuss the chronic intermittent alcohol vapor model, extensively utilized to induce a phenotype resembling dependence through non-contingent inhalation of alcohol vapor, resulting in elevated blood alcohol concentrations. Given the focus on pharmacological treatments for AUDs, we explore how different animal models can be employed to evaluate potential therapies and extrapolate findings to alcohol-related behaviors in humans. This chapter aims to provide readers with a comprehensive understanding of various animal models for AUDs, aiding in the interpretation of preclinical studies and the selection of suitable models for future research endeavors.

Mixing energy drinks and alcohol during adolescence impairs brain function: A study of rat hippocampal plasticity

In the last decades, the consumption of energy drinks has risen dramatically, especially among young people, adolescents and athletes, driven by the constant search for ergogenic effects, such as the increase in physical and cognitive performance. In parallel, mixed consumption of energy drinks and ethanol, under a binge drinking modality, under a binge drinking modality, has similarly grown among adolescents. However, little is known whether the combined consumption of these drinks, during adolescence, may have long-term effects on central function, raising the question of the risks of this habit on brain maturation. Our study was designed to evaluate, by behavioral, electrophysiological and molecular approaches, the long-term effects on hippocampal plasticity of ethanol (EtOH), energy drinks (EDs), or alcohol mixed with energy drinks (AMED) in a rat model of binge-like drinking adolescent administration. The results show that AMED binge-like administration produces adaptive hippocampal changes at the molecular level, associated with electrophysiological and behavioral alterations, which develop during the adolescence and are still detectable in adult animals. Overall, the study indicates that binge-like drinking AMED adolescent exposure represents a habit that may affect permanently hippocampal plasticity.

Physical training mitigates alveolar bone and blood enzymatic antioxidants defense impairment induced by binge ethanol consumption in rats

We aimed to investigate the effectiveness of physical training as a protective strategy to mitigate alveolar bone damage and blood antioxidant defense caused by ethanol (EtOH) consumption in a binge-drinking pattern. Male Wistar rats aged approximately 90 days were divided into four groups: control, training, EtOH, and training + EtOH. The physical training protocol was conducted on a treadmill for four consecutive weeks, while the animals in the EtOH group were administered EtOH via orogastric gavage for three consecutive days each week, following the binge drink pattern. After the training period, blood and mandibles were collected for plasma oxidative biochemistry analysis, and the alveolar bone was subjected to physicochemical composition analysis, tissue evaluation, and microtomography evaluation. Our results showed that EtOH induced oxidative stress and physical exercise promoted the recovery of antioxidant action. Physical training minimized the damage to the mineral/matrix composition of the alveolar bone due to EtOH consumption and increased the density of osteocytes in the trained group treated with EtOH than in those exposed only to EtOH. Furthermore, physical training reduced damage to the alveolar bone caused by EtOH consumption. Our findings suggest that physical training can serve as an effective strategy to reduce systemic enzymatic oxidative response damage and alleviate alveolar bone damage resulting from alcohol consumption. Further investigations are warranted to elucidate the underlying mechanisms and explore, in addition to physical training, the potential effects of other activities with varying intensities on managing alcohol-induced bone damage.

Epigenetic drugs and psychedelics as emerging therapies for alcohol use disorder: insights from preclinical studies

Alcohol use disorder (AUD) is a public health issue that affects millions of people worldwide leading to physical, mental and socio-economic consequences. While current treatments for AUD have provided relief to individuals, their effectiveness on the long term is often limited, leaving a number of affected individuals without sustainable solutions. In this review, we aim to explore two emerging approaches for AUD: psychedelics and epigenetic drugs (i.e., epidrugs). By examining preclinical studies, different animal species and procedures, we delve into the potential benefits of each of these treatments in terms of addictive behaviors (alcohol drinking and seeking, motivation to drink alcohol and prevention of relapse). Because psychedelics and epidrugs may share common and complementary mechanisms of action, there is an exciting opportunity for exploring synergies between these approaches and their parallel effectiveness in treating AUD and the diverse associated psychiatric conditions.

Binge ethanol exposure in advanced age elevates neuroinflammation and early indicators of neurodegeneration and cognitive impairment in female mice

Binge drinking is rising among aged adults (>65 years of age), however the contribution of alcohol misuse to neurodegenerative disease development is not well understood. Both advanced age and repeated binge ethanol exposure increase neuroinflammation, which is an important component of neurodegeneration and cognitive dysfunction. Surprisingly, the distinct effects of binge ethanol exposure on neuroinflammation and associated degeneration in the aged brain have not been well characterized. Here, we establish a model of intermittent binge ethanol exposure in young and aged female mice to investigate the effects of advanced age and binge ethanol on these outcomes. Following intermittent binge ethanol exposure, expression of pro-inflammatory mediators (tnf-α, il-1β, ccl2) was distinctly increased in isolated hippocampal tissue by the combination of advanced age and ethanol. Binge ethanol exposure also increased measures of senescence, the nod like receptor pyrin domain containing 3 (NLRP3) inflammasome, and microglia reactivity in the brains of aged mice compared to young. Binge ethanol exposure also promoted neuropathology in the hippocampus of aged mice, including tau hyperphosphorylation and neuronal death. We further identified advanced age-related deficits in contextual memory that were further negatively impacted by ethanol exposure. These data suggest binge drinking superimposed with advanced age promotes early markers of neurodegenerative disease development and cognitive decline, which may be driven by heightened neuroinflammatory responses to ethanol. Taken together, we propose this novel exposure model of intermittent binge ethanol can be used to identify therapeutic targets to prevent advanced age- and ethanol-related neurodegeneration.

Neural Circuitries and Alcohol Use Disorder: Cutting Corners in the Cycle

An implicit tenet of the alcohol use disorder (AUD) research field is that knowledge of how alcohol interacts with the brain is critical to the development of an understanding of vulnerability to AUD and treatment approaches. Gaining this understanding requires the mapping of brain function critical to specific components of this heterogeneous disorder. Early approaches in humans and animal models focused on the determination of specific brain regions sensitive to alcohol action and their participation in AUD-relevant behaviors. Broadly speaking, this research has focused on three domains, Binge/Intoxication, Negative Affect/Withdrawal, and Preoccupation/Anticipation, with a number of regions identified as participating in each. With the generational advances in technologies that the field of neuroscience has undergone over the last two decades, this focus has shifted to a circuit-based analysis. A wealth of new data has sharpened the field's focus on the specific roles of the interconnectivity of multiple brain regions in AUD and AUD-relevant behaviors, as well as demonstrating that the three major domains described above have much fuzzier edges than originally thought.In this chapter, we very briefly review brain regions previously implicated in aspects of AUD-relevant behavior from animal model research. Next, we move to a more in-depth overview of circuit-based approaches, and the utilization of these approaches in current AUD research.

Sex differences in ethanol consumption and drinking despite negative consequences following adolescent social isolation stress in male and female rats

Alcohol use disorder (AUD) is a debilitating psychiatric disorder characterized by drinking despite negative social and biological consequences. AUDs make up 71% of substance use disorders, with relapse rates as high as 80%. Current treatments stem from data conducted largely in males and fail to target the psychological distress motivating drinking in stress-vulnerable and at-risk populations. Here we employed a rat model and hypothesized that early life stress would reveal sex differences in ethanol intake and drinking despite negative consequences in adulthood. Rats were group housed or isolated postweaning to evaluate sex and stress effects on ethanol consumption in homecage drinking, self-administration (SA), and punished SA (drinking despite negative consequences) in adulthood. Stressed rats showed elevated homecage ethanol intake, an effect more pronounced in females. During SA, males were more sensitive to stress-induced elevations of drinking over time, but females drank more overall. Stressed rats, regardless of sex, responded more for ethanol than their non-stressed counterparts. Stressed females showed greater resistance to punishment-suppressed SA than stressed males, indicating a more stress-resistant drinking phenotype. Results support our hypothesis that adolescent social isolation stress enhances adult ethanol intake in a sex- and model-dependent manner with females being especially sensitive to early life stress-induced elevations in ethanol intake and punished SA in adulthood. Our findings echo the clinical literature which indicates that stress-vulnerable populations are more likely to 'self-medicate' with substances. Elucidating a potential mechanism that underlies why vulnerable populations 'self-medicate' with alcohol can lead towards developing catered pharmacotherapeutics that could reduce punishment-resistant drinking and relapse.

Binging from Food to Alcohol: A Sequential Interaction Between Binging Behaviors in Male Wistar Rats

The development of excessive alcohol (ethanol) and/or highly palatable food self-administration is an essential task to elucidate the neurobiological mechanisms that underlie these behaviors. Previous work has highlighted that ethanol self-administration is modulated by both the induction of aversive states (i.e., stress or frustration) and by the concurrent availability of appetitive stimuli (e.g., food). In our protocol, rats are food deprived for three days until they reach 82%-85% of their ad libitum weight. After that, rats are exposed daily for 10 days to a brief binge or control eating experience with highly sugary and palatable food (i.e., the ingestion of 11.66 and 0.97 kcal/3 min, respectively), which is followed by a two-bottle-choice test (ethanol vs. water) in their home cages for 90 min. This model induces robust binge eating, which is followed by a selective increase in ethanol self-administration. Therefore, this protocol allows to study: a) behavioral and neurobiological factors related to binge eating, b) different stages of alcohol use, and c) interactions between the latter and other addictive-like behaviors, like binge eating.

Intermittent Exposure to a Single Bottle of Ethanol Modulates Stress Sensitivity: Impact of Age at Exposure Initiation

Alcohol use during adolescence is a serious public health problem, with binge drinking and high-intensity drinking being particularly harmful to the developing adolescent brain. To investigate the adverse consequences of binge drinking and high-intensity adolescent drinking, adolescent rodents were intermittently exposed to ethanol through intragastric gavage, intraperitoneal injection, or vapor inhalation. These models revealed the long-lasting behavioral and neural consequences of adolescent intermittent ethanol (AIE) exposure. The present study was designed to characterize a different AIE model, namely, intermittent exposure to a single bottle of 10% ethanol as the only source of fluids on a 2 days on/2 days off (water days) schedule, and to determine whether this AIE exposure model would produce changes in hormonal and neuroimmune responsiveness to challenges of differing modalities. Assessments of ethanol intake as well as blood and brain ethanol concentrations (BECs and BrECs, respectively) in adult male and female rats (Experiment 1) revealed that BECs and BrECs peaked following access to ethanol for a 2 h period when assessed 1 h into the dark cycle. Experiment 2 revealed age differences in ethanol intake, BECs, and BrECs following a 2 h access to ethanol (1 h into the dark cycle), with adolescents ingesting more ethanol and reaching higher BECs as well as BrECs than adults. In Experiment 3, intermittent exposure to a single bottle of 10% ethanol for 10 cycles of 2 days on/2 days off was initiated either in early or late adolescence, followed by an acute systemic immune challenge with lipopolysaccharide (LPS) in adulthood. LPS increased corticosterone and progesterone levels regardless of sex and prior ethanol history, whereas an LPS-induced increase in cytokine gene expression in the hippocampus was evident only in ethanol-exposed males and females, with females who underwent early exposure to ethanol being more affected than their later-exposed counterparts. In Experiment 4, intermittent ethanol exposure in females was initiated either in adolescence or adulthood and lasted for 12 ethanol exposure cycles. Then, behavioral (freezing behavior), hormonal (corticosterone and progesterone levels), and neuroimmune (cytokine gene expression in the PVN, amygdala, and hippocampus) responses to novel environments (mild stressors) and shock (intense stressors) were assessed. More pronounced behavioral and hormonal changes, as well as changes in cytokine gene expression, were evident in the shock condition than following placement in the novel environment, with prior history of ethanol exposure not playing a substantial role. Interleukin (IL)-1β gene expression was enhanced by shock in the PVN, whereas shock-induced increases in IL-6 gene expression were evident in the hippocampus. Together, these findings demonstrate that our intermittent adolescent exposure model enhances responsiveness to immune but not stress challenges, with females being more vulnerable to this AIE effect than males.

Alcohol-sourced acetate impairs T cell function by promoting cortactin acetylation

Alcohol is among the most widely consumed dietary substances. Excessive alcohol consumption damages the liver, heart, and brain. Alcohol also has strong immunoregulatory properties. Here, we report how alcohol impairs T cell function via acetylation of cortactin, a protein that binds filamentous actin and facilitates branching. Upon alcohol consumption, acetate, the metabolite of alcohol, accumulates in lymphoid organs. T cells exposed to acetate, exhibit increased acetylation of cortactin. Acetylation of cortactin inhibits filamentous actin binding and hence reduces T cell migration, immune synapse formation and activation. While mutated, acetylation-resistant cortactin rescues the acetate-induced inhibition of T cell migration, primary mouse cortactin knockout T cells exhibited impaired migration. Acetate-induced cytoskeletal changes effectively inhibited activation, proliferation, and immune synapse formation in T cells in vitro and in vivo in an influenza infection model in mice. Together these findings reveal cortactin as a possible target for mitigation of T cell driven autoimmune diseases.

Sex-related differences in the efficacy of Baclofen enantiomers on self-administered alcohol in a binge drinking pattern and dopamine release in the core of the nucleus accumbens

Introduction: Clinical studies on the effectiveness of Baclofen in alcohol use disorder (AUD) yielded mixed results possibly because of differential effects of the enantiomers and sex-related differences. Here we examined the effect of the different Baclofen enantiomers on alcohol intake and on evoked dopamine release in the core of the nucleus accumbens (NAcc) in male and female Long Evans rats.

Methods: Rats were trained to chronically self-administer 20% alcohol solution in daily binge drinking sessions and were treated with the different forms of Baclofen [RS(±), R(+) and S(−)]. The effects on the evoked dopamine release within the core of the nucleus accumbens were measured in brain slices from the same animals and the alcohol naïve animals using the fast scan cyclic voltammetry technique.

Results: RS(±)-Baclofen reduced alcohol intake regardless of sex but more females were non-responders to the treatment. R(+)-Baclofen also reduced alcohol intake regardless of sex but females were less sensitive than males. S(−)-Baclofen did not have any effect on average but in some individuals, especially in the females, it did increase alcohol intake by at least 100%. There were no sex differences in Baclofen pharmacokinetic but a strong negative correlation was found in females with a paradoxical effect of increased alcohol intake with higher blood Baclofen concentration. Chronic alcohol intake reduced the sensitivity to the effect of Baclofen on evoked dopamine release and S(−)-Baclofen increased dopamine release specifically in females.

Discussion: Our results demonstrate a sex-dependent effect of the different forms of Baclofen with no or negative effects (meaning an increase in alcohol self-administration) in subgroup of females that could be linked to a differential effect on dopamine release and should warrant future clinical studies on alcohol use disorder pharmacotherapy that will deeply analyze sex difference.

Global brain c-Fos profiling reveals major functional brain networks rearrangements after alcohol reexposure

Many fundamental questions on alcohol use disorder (AUD) are frequently difficult to address by examining a single brain structure, but should be viewed from the whole brain perspective. c-Fos is a marker of neuronal activation. Global brain c-Fos profiling in rodents represents a promising platform to study brain functional networks rearrangements in AUD. We used a mouse model of alcohol drinking in IntelliCage. We trained mice to voluntarily drink alcohol, next subjected them to withdrawal and alcohol reexposure. We have developed a dedicated image computational workflow to identify c-Fos-positive cells in three-dimensional images obtained after whole-brain optical clearing and imaging in the light-sheet microscope. We provide a complete list of 169 brain structures with annotated c-Fos expression. We analyzed functional networks, brain modularity and engram index. Brain c-Fos levels in animals reexposed to alcohol were different from both control and binge drinking animals. Structures involved in reward processing, decision making and characteristic for addictive behaviors, such as precommissural nucleus, nucleus Raphe, parts of colliculus and tecta stood out particularly. Alcohol reexposure leads to a massive change of brain modularity including a formation of numerous smaller functional modules grouping structures involved in addiction development. Binge drinking can lead to substantial functional remodeling in the brain. We provide a list of structures that can be used as a target in pharmacotherapy but also point to the networks and modules that can hold therapeutic potential demonstrated by a clinical trial in patients.

Preconception paternal alcohol exposure decreases IVF embryo survival and pregnancy success rates in a mouse model

Increasingly, couples struggling with fertility turn to assisted reproductive techniques, including IVF, to have children. Despite the demonstrated influence of periconception male health and lifestyle choices on offspring development, studies examining IVF success rates and child health outcomes remain exclusively focused on maternal factors. Using a physiologically relevant mouse model, we tested the hypothesis that chronic paternal preconception alcohol intake adversely affects IVF success and negatively impacts IVF offspring fetoplacental growth. Using a voluntary, binge-like mouse model, we exposed sexually mature C57BL/6J males to three preconception treatments (0% (Control), 6% EtOH or 10% EtOH) for 6 weeks, isolated and cryopreserved caudal sperm from treated males, and then used these samples to fertilize oocytes before assessing IVF embryo developmental outcomes. We found that preconception paternal alcohol use reduced IVF embryo survival and pregnancy success rates in a dose-dependent manner, with the pregnancy success rate of the 10% EtOH treatment falling to half those of the Controls. Mechanistically, we found that preconception paternal alcohol exposure disrupts embryonic gene expression, including Fgf4 and Egfr, two critical regulators of trophectoderm stem cell growth and placental patterning, with lasting impacts on the histological organization of the late-term placenta. The changes in placental histoarchitecture were accompanied by altered regulation of pathways controlling mitochondrial function, oxidative phosphorylation and some imprinted genes. Our studies indicate that male alcohol use may significantly impede IVF success rates, increasing the couple's financial burden and emotional stress, and highlights the need to expand prepregnancy messaging to emphasize the reproductive dangers of alcohol use by both parents.

Sex-specific decision-making impairments and striatal dopaminergic changes after binge drinking history in rats

Binge drinking (BD) is a harmful behavior for health and is a predictive factor for the development of alcohol addiction. Weak decision-making (DM) capacities could play a role in the vulnerability to BD which in turn would lead to DM impairments, thus perpetuating BD. Longitudinal preclinical studies are however lacking and necessary to understand this complex relationship. Both DM and BD are influenced by sex and involve dopamine release in the core of the nucleus accumbens, a central mechanism regulated by dopamine D2/3 autoreceptors. In this context, we used an operant self-administration procedure of BD in male and female rats, and longitudinally assessed DM capacity, memory and anxiety-like behavior. To better understand the mechanisms potentially involved in the relationship between DM and BD, ex vivo dopamine transmission was assessed short term after the end of the binge exposure in the core of the nucleus accumbens (NAc) using the fast-scan cyclic voltammetry (FSCV) technique and the D2/3 agonist quinpirole. We found important basal sex differences in DM, with female rats showing better performances at baseline. Choice processes were impaired exclusively in males after BD history, associated with a decrease in impulse control in both sexes, while memory and anxiety-like behavior were not affected. Our neurobiological results demonstrate that BD did not affect basal dopamine signaling in the NAc core, regardless of the sex, but reveal changes in the sensitivity to the inhibitory effects of quinpirole in females. DM impairments were neither associated with changes in basal dopamine signaling nor pre-synaptic D2 activity. Overall, our findings show that BD affects both DM processes and dopamine transmission in the core of the NAc in a sex-related manner, further suggesting that these effects may play a role in the vicious cycle leading to BD perpetuation and the early onset of AUD. Our results may inform novel strategies for therapeutic and prevention interventions.

Construction and evaluation of an alcohol vapor chamber system

An increasing number of studies demonstrated that alcohol vapor chamber is an effective way to model physical signs of alcohol use disorders. Although researchers are developing different vapor chambers to study chronic alcohol exposure model worldwide, few studies build and modify their own vapor chambers in China. Here, we designed and established an alcohol vapor chamber system for small animals. We described a paradigm showing how to control and monitor alcohol concentration in whole system. The vapor chamber system with several advantages including accommodating up to ten standard mouse cages. Furthermore, the system was tested by evaluating the blood alcohol concentration and neuron injury in mice. Importantly, the alcohol withdrawal after vapor exposure caused motor coordination impairment, anxiolytic- and depression-like behavior. Finally, the N-methyl-D-aspartate receptor (NMDAR)-mediated glutamatergic transmissions in the medial prefrontal cortex was changed after alcohol vapor exposure-induced behaviors. The frequency and amplitude of spontaneous excitatory postsynaptic currents between control and alcohol groups were not different, suggesting that alcohol exposure-induced behaviors are associated with the change in NMDAR response. Taken together, the new alcohol vapor chamber system was constructed, which would help to research the relationship between the stable alcohol exposure and withdrawal behaviors and to study chronic alcohol exposure-induced disorders in China.

Ethanol and its Nonoxidative Metabolites Promote Acute Liver Injury by Inducing ER Stress, Adipocyte Death, and Lipolysis

BACKGROUND & AIMS

Binge drinking in patients with metabolic syndrome accelerates the development of alcohol-associated liver disease. However, the underlying mechanisms remain elusive. We investigated if oxidative and nonoxidative alcohol metabolism pathways, diet-induced obesity, and adipose tissues influenced the development of acute liver injury in a single ethanol binge model.

METHODS

A single ethanol binge was administered to chow-fed or high-fat diet (HFD)-fed wild-type and genetically modified mice.

RESULTS

Oral administration of a single dose of ethanol induced acute liver injury and hepatic endoplasmic reticulum (ER) stress in chow- or HFD-fed mice. Disruption of the Adh1 gene increased blood ethanol concentration and exacerbated acute ethanol-induced ER stress and liver injury in both chow-fed and HFD-fed mice, while disruption of the Aldh2 gene did not affect such hepatic injury despite high blood acetaldehyde levels. Mechanistic studies showed that alcohol, not acetaldehyde, promoted hepatic ER stress, fatty acid synthesis, and increased adipocyte death and lipolysis, contributing to acute liver injury. Increased serum fatty acid ethyl esters (FAEEs), which are formed by an enzyme-mediated esterification of ethanol with fatty acids, were detected in mice after ethanol gavage, with higher levels in Adh1 knockout mice than in wild-type mice. Deletion of the Ces1d gene in mice markedly reduced the acute ethanol-induced increase of blood FAEE levels with a slight but significant reduction of serum aminotransferase levels.

CONCLUSIONS

Ethanol and its nonoxidative metabolites, FAEEs, not acetaldehyde, promoted acute alcohol-induced liver injury by inducing ER stress, adipocyte death, and lipolysis.

Dichrocephala integrifolia Aqueous Extract Antagonises Chronic and Binges Ethanol Feeding-Induced Memory Dysfunctions: Insights into Antioxidant and Anti-Inflammatory Mechanisms

Ethanol consumption is widely accepted despite its addictive properties and its mind-altering effects. This study aimed to assess the effects of Dichrocephala integrifolia against, memory impairment, on a mouse model of chronic and binges ethanol feeding. Mice were divided, into groups of 8 animals each, and received distilled water, Dichrocephala integrifolia aqueous extract (25; 50; 100; or 200 mg/kg) or memantine (200 mg/kg) once a day, while fe, with Lieber-DeCarli control (sham group only) or Lieber-DeCarli ethanol diet ad libitum for 28 days. The Y maze and the novel object recognition (NOR) tests were used to evaluate spatial short-term and recognition memory, respectively. Malondialdehyde, nitric oxide, glutathione levels, and proinflammatory cytokines (Il-1β, TNF-α, and Il-6) were evaluated in brain homogenates following behavioral assessments. The results showed that chronic ethanol administration in mice was associated with a significant (p < 0.001) reduction in the spontaneous alternation percentage and the discrimination index, in the Y maze and the NOR tests, respectively. It significantly (p < 0.01) increased oxidative stress and inflammation markers levels in the brain. Dichrocephala integrifolia (100 and 200 mg/kg) as well as memantine (200 mg/kg) significantly (p < 0.001) increased the percentage of spontaneous alternation and the discrimination index, in the Y maze and NOR tests, respectively. Dichrocephala integrifolia (100 and 200 mg/kg) likewise memantine (200 mg/kg) significantly (p < 0.01) alleviated ethanol-induced increase, in the brain malondialdehyde level, nitric oxide, Il-1β, TNF-α, and Il-6. From these findings, it can be concluded that Dichrocephala integrifolia counteracted memory impairment, oxidative stress, and neuroinflammation induced by chronic ethanol consumption in mice.

Impact of alcohol-induced intestinal microbiota dysbiosis in a rodent model of Alzheimer's disease

Introduction: Alzheimer's disease (AD) is a devastating neurodegenerative disorder. While genetics are important in the development of AD, environment and lifestyle are also important factors influencing AD. One such lifestyle factor is alcohol consumption. Unhealthy and excessive chronic alcohol consumption is associated with a greater risk of all types of dementia, especially AD. Alcohol consumption has numerous effects on the body, including alterations to the intestinal microbiota (dysbiosis) and intestinal barrier dysfunction (leakiness and intestinal hyperpermeability), with evidence indicating that inflammation resulting from dysbiosis and barrier dysfunction can promote neuroinflammation impacting brain structure and function. Objective: This study sought to determine the impact of alcohol-induced dysbiosis and barrier dysfunction on AD-like behavior and brain pathology using a transgenic rodent model of AD (3xTg-AD). Methods: Alcohol (20%) was administered to 3xTg-AD mice in the drinking water for 20 weeks. Intestinal (stool) microbiota, intestinal barrier permeability, systemic inflammation (IL-6), behavior, and AD pathology (phosphorylated tau and β-amyloid), and microglia were examined. Results: Alcohol consumption changed the intestinal microbiota community (dysbiosis) and increased intestinal barrier permeability in both control and 3xTg-AD mice (oral/urine sugar test and lipopolysaccharide-binding protein (LBP)). However, alcohol consumption did not influence serum IL-6, behavior, or β-amyloid, phosphorylated tau, or microglia in 3xTg-AD mice. Important differences in genotype and sex were noted. Conclusion: Alcohol-induced microbiota dysbiosis and intestinal barrier dysfunction did not exacerbate behavior or AD-like brain pathology in the 3xTg-AD mouse model of AD which could, in part, be the result of a lack of systemic inflammation.

Development of eight wireless automated cages system with two lick-o-meters each for rodents

Drinking behavior has been used in basic research to study metabolism, motivation, decision-making and different aspects of health problems, such as anhedonia and alcohol use disorders. In the majority of studies, liquid intake is measured by weighing the bottles before and after the experiment. This method does not tell much about the drinking microstructure, e.g., licking bouts and periods of preference for each liquid, which could be valuable to understand drinking behavior. To improve the data acquisition of drinking microstructure, companies have developed lick-o-meters devices that acquire timestamps when animals approach or drink from a specific sipper. Nevertheless, commercially available devices have elevated costs. Here, we present a low-cost alternative for a lick-o-meter system that allows wireless data acquisition of licking from eight cages with two sippers each. We run a three-phase validation protocol to ensure 1) proper choice of the sensor to detect licks; 2) adaptation of the device to a wireless transmission and realistic in silico tests; and 3) in vivo tests to correlate the amount of licks measured by the prototype and the bottle weight. The capacitive sensor presented appropriate recall and precision for our device. After adaptation to wireless transmission, the in silico validation demonstrated low reading and transmission errors for the device even when tested in extreme simultaneous licking conditions. Finally, a positive correlation between volume consumption and lick's count in the in vivo test was observed, showing that the prototype can be used for in vivo studies interested in rodent drinking microstructure.Significant StatementThis study presents an innovative and low-cost solution for drinking behavioral studies: a lick-o-meter system based on an open-source hardware platform with a user-friendly interface software, capable of simultaneously receiving data from eight automated cages with two drinking bottles each. The lick-o-meter brings an accessible device to acquire high-quality and detailed data. This device also has the possibility to be adaptable to new types of sensors or other neuroscience tools capable of measuring brain activity simultaneously to the behavior.

Binge drinking during the adolescence period causes oxidative damage-induced cardiometabolic disorders: A possible ameliorative approach with selenium supplementation

Binge drinking (BD) is the most common alcohol consumption model among adolescents. BD exposure during adolescence disrupts the nervous system function, being involved in the major mortality causes at this age: motor vehicle accidents, homicides and suicides. Recent studies have also shown that BD consumption during adolescence affects liver, renal and cardiovascular physiology, predisposing adolescents to future adult cardiometabolic damage. BD is a particularly pro-oxidant alcohol consumption pattern, because it leads to the production of a great source of reactive oxygen species (ROS) via the microsomal ethanol oxidizing system, also decreasing the antioxidant activity of glutathione peroxidase (GPx). Selenium (Se) is a mineral which plays a pivotal role against oxidation; it forms part of the catalytic center of different antioxidant selenoproteins such as GPxs (GPx1, GPx4, GPx3) and selenoprotein P (SelP). Specifically, GPx4 has an essential role in mitochondria, preventing their oxidation, apoptosis and NFkB-inflamative response, being this function even more relevant in heart's tissue. Se serum levels are decreased in acute and chronic alcoholic adult patients, being correlated to the severity of oxidation, liver damage and metabolic profile. Experimental studies have described that Se supplementation to alcohol exposed mice clearly decreases oxidative and liver damage. However, clinical BD effects on Se homeostasis and selenoproteins' tissue distribution related to oxidation during adolescence are not yet studied. In this narrative review we will describe the use of sodium selenite supplementation as an antioxidant therapy in adolescent BD rats in order to analyze Se homeostasis implication during BD exposure, oxidative balance, apoptosis and inflammation, mainly in liver, kidney, and heart. These biomolecular changes and the cardiovascular function will be analyzed. Se supplementation therapies could be a good strategy to prevent the oxidation, inflammation and apoptosis generated in tissues by BD during adolescence, such as liver, kidney and heart, improving cardiovascular functioning.

From binge eating to binge drinking: A new and robust paradigm for assessing binge ethanol self-administration in male rats

Animal models of alcohol (ethanol) self-administration are crucial to dissect the neurobiological mechanisms underlying alcohol dependence, yet only a few of these induce pharmacologically relevant levels of alcohol consumption and rarely the alcohol self-administration co-occurs with other addictive behaviours. The present study aims to validate a novel model of voluntary ethanol consumption in male Wistar rats, in which ethanol access follows a binge eating experience. Over 10 sessions, Wistar rats were exposed to binge or control eating (i.e., the ingestion of 11.66 and 0.97 kcal/3 min, respectively, derived from a highly palatable food), immediately followed by two-bottle choice intake tests (2%, 6%, 10% or 14% w/w ethanol vs. water). Rats exposed to binge eating drank significantly more 6% or 10% (w/w) ethanol than control peers, reaching up to 6.3 g_EtOH /kg. Rats stimulated with 2%, 6%, 10% or 14% ethanol after binge eating, but not those given those ethanol concentrations after control eating, exhibited significant within-group increases in ethanol drinking. This ethanol consumption was not altered by quinine adulteration (up to 0.1 g/L), and it was blocked by naltrexone (10 mg/kg), administered immediately before binge eating. Blood ethanol levels significantly correlated with ethanol consumption; and the more ethanol consumed, the greater the distance travelled in an open field test conducted after the two-bottle choice test. Altogether, this self-administration model seems a valid and robust alternative with remarkable potential for research on different stages of the alcohol addiction and, particularly, to assess interactions between alcohol consumption and others addictive-like behaviours.

Shortening time for access to alcohol drives up front-loading behavior, bringing consumption in male rats to the level of females

Background

Incentives to promote drinking (“happy hour”) can encourage faster rates of alcohol consumption, especially in women. Sex differences in drinking dynamics may underlie differential health vulnerabilities relating to alcohol in women versus men. Herein, we used operant procedures to model the happy hour effect and gain insight into the alcohol drinking dynamics of male and female rats.

Methods

Adult male and female Wistar rats underwent operant training to promote voluntary drinking of 10% (w/v) alcohol (8 rats/sex). We tested how drinking patterns changed after manipulating the effort required for alcohol (fixed ratio, FR), as well as the length of time in which rats had access to alcohol (self-administration session length). Rats were tested twice within the 12 h of the dark cycle, first at 2 h (early phase of the dark cycle, “early sessions”) and then again at 10 h into the dark cycle (late phase of the dark cycle, “late sessions”) with an 8-h break between the two sessions in the home cage.

Results

Adult females consumed significantly more alcohol (g/kg) than males in the 30-min sessions with the FR1 schedule of reinforcement when tested late in the dark cycle. Front-loading of alcohol was the primary factor driving higher consumption in females. Changing the schedule of reinforcement from FR1 to FR3 reduced total consumption. Notably, this manipulation had minimal effect on front-loading behavior in females, whereas front-loading behavior was significantly reduced in males when more effort was required to access alcohol. Compressing drinking access to 15 min to model a happy hour drove up front-loading behavior, generating alcohol drinking patterns in males that were similar to patterns in females (faster drinking and higher intake).

Conclusions

This strategy could be useful for exploring sex differences in the neural mechanisms underlying alcohol drinking and related health vulnerabilities. Our findings also highlight the importance of the time of testing for detecting sex differences in drinking behavior.

Voluntary alcohol drinking is higher in adult female rats compared to adult male rats. This sex difference is most pronounced in the later phase of the dark cycle, and when the operant effort is minimal (when 1 lever press gives 1 reward: fixed ratio 1, FR1).

Higher alcohol intake in females is primarily due to “front-loading”, or the rapid consumption of alcohol within the first 5 min of access.

Increasing the effort required to obtain alcohol from FR1 to FR3 dampens front-loading drinking behavior, resulting in similar levels of total intake in males and females.

Compressing the time of access to 15 min drives up front-loading to such a degree that rats end up consuming more alcohol in total than they do in 30-min sessions. In males, this increase in drinking is large enough that it eliminates the sex difference in total alcohol intake.

Contribution of Fatty Acid Amide Hydrolase to Alcohol Use Disorder: A Systematic Review

Purpose: Recent research has suggested that chronic alcohol exposure induces changes in the endocannabinoid system within the central nervous system and therefore could be an attractive target for better understanding and treating alcohol use disorder (AUD). Much of this research has centered around the CB₁ receptor and its endogenous partial agonist, the endocannabinoid anandamide, as the CB₁ receptor is densely expressed in brain regions involved in development and maintenance of addictive behaviors. In addition, recent evidence has suggested that chronic alcohol exposure induces changes in the modulation of endocannabinoid concentration and suggests that these changes may contribute to the motivation to abuse alcohol. Therefore, we performed a systematic literature review to evaluate how fatty acid amide hydrolase (FAAH), an enzyme that degrades anandamide, relates to the characteristics and biology of AUD, as well as how modulating FAAH through pharmacologic inhibition or genetic manipulation affects outcomes related to alcohol use and consumption. Method: A search strategy was developed using the terms "endocannabinoids" or "drug delivery systems" and "alcohol dependence" or "alcohol use disorder" or "alcoholism" and "Fatty Acid Amide Hydrolase" and "FAAH" as text words and Medical Subject Headings (i.e., MeSH and EMTREE). We then used this search strategy on the electronic databases PubMed, Embase, and Web of Science. Results: We found 224 records; after removing repeated records (37%), articles that did not fit the topic question (47%), or were not primary research (4%), we included 26 for qualitative synthesis (12%). Discussion: The literature clearly suggests that FAAH has a role in the biology and characteristics of AUD. FAAH inhibition seems especially promising as a target for alcohol withdrawal as it may lead to a reduction in symptoms, including anxiety and a reduction of alcohol intake reinstatement. However, decreased FAAH may also lead to reduced sensitivity to alcohol along with increased preference and intake. Conclusions: Modulation of FAAH is promising for therapeutic intervention of AUD, but requires more research. Pre-clinical studies have indicated that FAAH inhibition may reduce withdrawal characteristics, but may also exacerbate other characteristics of AUD outside of that period.

Is R(+)-Baclofen the best option for the future of Baclofen in alcohol dependence pharmacotherapy? Insights from the preclinical side

For several decades, studies conducted to evaluate the efficacy of RS(±)-Baclofen in the treatment of alcohol dependence yielded contrasting results. Human and animal studies recently questioned the use of the racemic drug in patients since a potential important role of the different enantiomers has been revealed with an efficacy thought to reside with the active R(+)-enantiomer. Here we conducted experiments in the postdependent rat model of alcohol dependence to compare the efficacy of R(+)-Baclofen or S(-)-Baclofen to that of RS(±)-Baclofen on ethanol intake, seeking, and relapse. R(+)-Baclofen was more effective than RS(±)-Baclofen in reducing ethanol intake and seeking during acute withdrawal and during relapse after abstinence. We also used an original population approach in order to identify drug responders. We found a significant proportion of responders to S(-)-Baclofen and RS(±)-Baclofen, displaying an increase in ethanol intake, and this increasing effect on alcohol intake was not seen in the R(+)-Baclofen group. At an intermediate dose of R(+)-Baclofen, devoid of any motor side effects, we identified a very large proportion of responders (75%) with a large decrease in ethanol intake (90% decrease). Finally, the response to RS(±)-Baclofen on ethanol intake was correlated to plasma level of Baclofen. R(+)-Baclofen and RS(±)-Baclofen were effective in reducing sucrose intake. Our study has important clinical implication since it suggests that the wide variability in the therapeutic responses of patients to RS(±)-Baclofen may come from the sensitivity to the R(+)-Baclofen but also to the one of the S(-)-Baclofen that can promote an increase in ethanol intake.

Patch-Clamp Recording of Low Frequency Stimulation-induced Long-Term Synaptic Depression in Rat Hippocampus Slices During Early and Late Neurodevelopment

BACKGROUND

Studying synaptic plasticity in the rat hippocampus slice is a well-established way to analyze cellular mechanisms related to learning and memory. Different modes of recording can be used, such as extracellular field excitatory post-synaptic potential (EPSP) and diverse patch-clamp methods. However, most studies using these methods have examined only up to the juvenile stage of brain maturation, which is known to terminate during late adolescence/early adulthood. Moreover, several animal models of human diseases have been developed at this late stage of brain development. To study the vulnerability of adolescent rat to the cognitive impairment of alcohol, we developed a model of binge-like exposure in which ethanol selectively abolishes low frequency stimulation (LFS)-induced, field EPSP long-term depression (LTD) in the rat hippocampus slice.

METHODS

In the present study, we sought to use whole-cell patch-clamp recording in the voltage-clamp mode to further investigate the mechanisms involved in the abolition of LFS-induced LTD in our model of binge-like exposure in adolescent rat hippocampus slices. In addition, we investigated LFS-induced NMDAR-LTD and mGluR-LTD at different ages and changed several parameters to improve the recordings.

RESULTS

Using patch-clamp recording, LFS-induced NMDAR-LTD and mGluR-LTD could be measured until 4 weeks of age, but not in older animals. Similarly, chemical mGluR-LTD and a combined LFS-LTD involving both N-Methyl-D-Aspartate Receptor (NMDAR) and mGluR were not measured in older animals. The absence of LFS-LTD was not due to the loss of a diffusible intracellular agent nor the voltage mode of recording or intracellular blockade of either sodium or potassium currents. In contrast to voltage-clamp recordings, LFS-induced LTD tested with field recordings was measured at all ages and the effects of EtOH were visible in all cases.

CONCLUSIONS

We concluded that whole-cell patch-clamp recordings are not suitable for studying synaptic LFS-induced LTD in rats older than 4 weeks of age and therefore cannot be used to explore electrophysiological disturbances, such as those induced by alcohol binge drinking during adolescence, which constitutes a late period of brain maturation.

Effects of naltrexone on alcohol, sucrose, and saccharin binge-like drinking in C57BL/6J mice: a study with a multiple bottle choice procedure

Chronic alcohol (ethyl alcohol, EtOH) binging has been associated with long-term neural adaptations that lead to the development of addiction. Many of the neurobiological features of EtOH abuse are shared with other forms of binging, like pathological feeding. The drinking-in-the-dark (DID) paradigm has been used extensively to study the neurobiology of EtOH binge-like drinking due to its ability to promote high intakes relevant to human behavior. DID can also generate high consumption of other tastants, but this procedure has not been fully adapted to study forms of binging behavior that are not alcohol-driven. In the present study, we used a modified version of DID that uses multiple bottle availability to promote even higher levels of EtOH drinking in male C57BL/6J mice and allows a thorough investigation of tastant preferences. We assessed whether administration of systemic naltrexone could reduce binging on EtOH, sucrose, and saccharin separately as well as in combination. Our multiple bottle DID procedure resulted in heightened levels of consumption compared with previously reported data using this task. We found that administration of the opioid receptor antagonist naltrexone reduced intakes of preferred, highly concentrated EtOH, sucrose, and saccharin. We also report that naltrexone was able to reduce overall intakes when animals were allowed to self-administer EtOH, sucrose, or saccharin in combination. Our modified DID procedure provides a novel approach to study binging behavior that extends beyond EtOH to other tastants (i.e. sucrose and artificial sweeteners), and has implications for the study of the neuropharmacology of binge drinking.

Environmental Enrichment During Adolescence Mitigates Cognitive Deficits and Alcohol Vulnerability due to Continuous and Intermittent Perinatal Alcohol Exposure in Adult Rats

Perinatal alcohol exposure affects ontogenic neurodevelopment, causing physical and functional long-term abnormalities with limited treatment options. This study investigated long-term consequences of continuous and intermittent maternal alcohol drinking on behavioral readouts of cognitive function and alcohol vulnerability in the offspring. The effects of environmental enrichment (EE) during adolescence were also evaluated. Female rats underwent continuous alcohol drinking (CAD)—or intermittent alcohol drinking paradigm (IAD), along pregestation, gestation, and lactation periods—equivalent to the whole gestational period in humans. Male offspring were reared in standard conditions or EE until adulthood and were then assessed for declarative memory in the novel object recognition test; spatial learning, cognitive flexibility, and reference memory in the Morris water maze (MWM); alcohol consumption and relapse by a two-bottle choice paradigm. Our data show that perinatal CAD decreased locomotor activity, exploratory behavior, and declarative memory with respect to controls, whereas perinatal IAD displayed impaired declarative memory and spatial learning and memory. Moreover, both perinatal alcohol-exposed offspring showed higher vulnerability to alcohol consummatory behavior than controls, albeit perinatal IAD rats showed a greater alcohol consumption and relapse behavior with respect to perinatal-CAD progeny. EE ameliorated declarative memory in perinatal CAD, while it mitigated spatial learning and reference memory impairment in perinatal-IAD progeny. In addition, EE decreased vulnerability to alcohol in both control and perinatal alcohol-exposed rats. Maternal alcohol consumption produces drinking pattern-related long-term consequences on cognition and vulnerability to alcohol in the offspring. However, increased positive environmental stimuli during adolescence may curtail the detrimental effects of developmental alcohol exposure.

Modeling alcohol-induced neurotoxicity using human induced pluripotent stem cell-derived three-dimensional cerebral organoids

Maternal alcohol exposure during pregnancy can substantially impact the development of the fetus, causing a range of symptoms, known as fetal alcohol spectrum disorders (FASDs), such as cognitive dysfunction and psychiatric disorders, with the pathophysiology and mechanisms largely unknown. Recently developed human cerebral organoids from induced pluripotent stem cells are similar to fetal brains in the aspects of development and structure. These models allow more relevant in vitro systems to be developed for studying FASDs than animal models. Modeling binge drinking using human cerebral organoids, we sought to quantify the downstream toxic effects of alcohol (ethanol) on neural pathology phenotypes and signaling pathways within the organoids. The results revealed that alcohol exposure resulted in unhealthy organoids at cellular, subcellular, bioenergetic metabolism, and gene expression levels. Alcohol induced apoptosis on organoids. The apoptotic effects of alcohol on the organoids depended on the alcohol concentration and varied between cell types. Specifically, neurons were more vulnerable to alcohol-induced apoptosis than astrocytes. The alcohol-treated organoids exhibit ultrastructural changes such as disruption of mitochondria cristae, decreased intensity of mitochondrial matrix, and disorganized cytoskeleton. Alcohol exposure also resulted in mitochondrial dysfunction and metabolic stress in the organoids as evidenced by (1) decreased mitochondrial oxygen consumption rates being linked to basal respiration, ATP production, proton leak, maximal respiration and spare respiratory capacity, and (2) increase of non-mitochondrial respiration in alcohol-treated organoids compared with control groups. Furthermore, we found that alcohol treatment affected the expression of 199 genes out of 17,195 genes analyzed. Bioinformatic analyses showed the association of these dysregulated genes with 37 pathways related to clinically relevant pathologies such as psychiatric disorders, behavior, nervous system development and function, organismal injury and abnormalities, and cellular development. Notably, 187 of these genes are critically involved in neurodevelopment, and/or implicated in nervous system physiology and neurodegeneration. Furthermore, the identified genes are key regulators of multiple pathways linked in networks. This study extends for the first time animal models of binge drinking-related FASDs to a human model, allowing in-depth analyses of neurotoxicity at tissue, cellular, subcellular, metabolism, and gene levels. Hereby, we provide novel insights into alcohol-induced pathologic phenotypes, cell type-specific vulnerability, and affected signaling pathways and molecular networks, that can contribute to a better understanding of the developmental neurotoxic effects of binge drinking during pregnancy.

GPCR and Alcohol-Related Behaviors in Genetically Modified Mice

G protein-coupled receptors (GPCRs) constitute the largest class of cell surface signaling receptors and regulate major neurobiological processes. Accordingly, GPCRs represent primary targets for the treatment of brain disorders. Several human genetic polymorphisms affecting GPCRs have been associated to different components of alcohol use disorder (AUD). Moreover, GPCRs have been reported to contribute to several features of alcohol-related behaviors in animal models. Besides traditional pharmacological tools, genetic-based approaches mostly aimed at deleting GPCR genes provided substantial information on how key GPCRs drive alcohol-related behaviors. In this review, we summarize the alcohol phenotypes that ensue from genetic manipulation, in particular gene deletion, of key GPCRs in rodents. We focused on GPCRs that belong to fundamental neuronal systems that have been shown as potential targets for the development of AUD treatment. Data are reviewed with particular emphasis on alcohol reward, seeking, and consumption which are behaviors that capture essential aspects of AUD. Literature survey indicates that in most cases, there is still a gap in defining the intracellular transducers and the functional crosstalk of GPCRs as well as the neuronal populations in which their signaling regulates alcohol actions. Further, the implication of only a few orphan GPCRs has been so far investigated in animal models. Combining advanced pharmacological technologies with more specific genetically modified animals and behavioral preclinical models is likely necessary to deepen our understanding in how GPCR signaling contributes to AUD and for drug discovery.

Alcohol Binge Drinking and Anxiety-Like Behavior in Socialized Versus Isolated C57BL/6J Mice

BACKGROUND

Binge alcohol drinking has been characterized as a key feature of alcoholism. The drinking-in-the-dark (DID) preclinical model, a procedure that promotes high levels of ethanol (EtOH) intake in short periods of time, has been extensively used to investigate neuropharmacological and genetic determinants of binge-like EtOH consumption. Using DID methodology, alcohol-preferring strains of mice such as C57BL/6J (B6) mice consume enough EtOH to achieve blood concentrations (≥1.0 mg/ml) associated with behavioral intoxication (i.e., motor incoordination). DID procedures typically involve the use of socially isolated animals (single-housed prior to and during the experiment). Previous research indicates that stress associated with social isolation can induce anxiety-like behavior and promote increases in EtOH intake. The present study investigates the role of housing conditions in anxiety-like behavior and binge-like EtOH intake using a DID procedure.

METHODS

Male and female B6 mice were isolated or pair-housed for a period of 6 weeks prior to evaluation of anxiety-like (elevated plus maze, light and dark box, open field) and drinking (water, 10% sucrose, 10 to 30% EtOH) behavior. In order to measure intake, a variation of the standard DID procedure using a removable, transparent, and perforated plastic barrier strip (designed to temporarily divide the cage in 2) was introduced. This allowed for individual intake records (2-hour test) of isolated and socially housed animals.

RESULTS

Increased anxiety-like behavior and reduced sucrose consumption were found in isolated mice. The effects of housing conditions on EtOH intake were sex- and concentration-dependent. In male mice, isolation increased 20 and 30% EtOH intake. In females, however, an increased intake of EtOH (30%) was found in socialized animals. No effects of housing or sex were found at EtOH 10%.

CONCLUSIONS

Together with previous literature, the present study suggests that social isolation can promote anxiety-associated behavior and produce sex-dependent changes in binge-like EtOH consumption.

Potential of GABAB Receptor Positive Allosteric Modulators in the Treatment of Alcohol Use Disorder

The orthosteric γ-aminobutyric acid_B (GABA_B) receptor agonist baclofen is currently considered a therapeutic option for alcohol use disorder (AUD); however, the safety profile of baclofen is a concern, thus arousing interest in the positive allosteric modulators (PAMs) of the GABA_B receptor (GABA_B PAMs), a new class of ligands expected to possess a better safety profile. The present paper summarizes the several lines of experimental evidence indicating the ability of GABA_B PAMs to inhibit multiple alcohol-motivated behaviors in rodents. All GABA_B PAMs tested to date have invariably been reported to reduce, or even suppress, excessive alcohol drinking, relapse- and binge-like drinking, operant oral alcohol self-administration, reinstatement of alcohol seeking, and alcohol-induced locomotor stimulation and conditioned place preference in rats and mice. The use of validated animal models of several aspects of AUD confers translational value to these findings. The reducing effects of GABA_B PAMs on alcohol-motivated behaviors (1) occurred at doses largely lower than those inducing sedation, suggesting that GABA_B PAMs may possess, if compared with baclofen, a higher therapeutic index and a more favorable safety profile, and (2) were often not associated with reductions on other non-drug consummatory behaviors. Additional findings with therapeutic potential were (1) the lack of tolerance, after repeated treatment, to the reducing effect of GABA_B PAMs on alcohol drinking and self-administration; (2) the efficacy of GABA_B PAMs after intragastric administration; and (3) the ability of GABA_B PAMs to selectively potentiate the suppressing effect of baclofen on alcohol self-administration. The recent transition of the first GABA_B PAMs to the initial steps of clinical testing makes investigation of the efficacy of GABA_B PAMs in AUD patients a feasible option.

Exploration of young adults' influences on, and consequences of, avoiding alcohol consumption

BACKGROUND

There is a wealth of research on motives for alcohol consumption among young people. However, little is known about motives to avoid alcohol in this population.

OBJECTIVES

The study purpose was to explore what influences young adults' decisions to avoid alcohol and their motives to avoid alcohol.

METHODS

Face-to-face, semi-structured, one-on-one interviews were conducted in 2015 with young adults (n = 30, M_age = 21.13 years, SD = 2.05) living in Australia who did not consume alcohol regularly. Interviews were analyzed using thematic content analysis.

RESULTS

Thematic analysis resulted in seven themes: being in control; avoiding negative health consequences; taste; socialization influences; being left out; peer pressure; strategies to curb excessive alcohol consumption. Conclusions/Importance: Findings from the present study contribute to the literature in identifying coping strategies that participants adopted when faced with questions concerning their abstinence. The data provide evidence that, even in a minority, strong identities and beliefs appear to be a robust means to counteract pressure to conform to the social norm to consume alcohol. Findings may inform the (1) development of youth-centered interventions that target values and social norms to help build resistance to pressures to consume alcohol from peers and the wider community and (2) creation of opportunities and promotion of activities that are fun and alcohol free.

Ethanol Conditioned Taste Aversion in High Drinking in the Dark Mice

Two independent lines of High Drinking in the Dark (HDID-1, HDID-2) mice have been bred to reach high blood alcohol levels after a short period of binge-like ethanol drinking. Male mice of both lines were shown to have reduced sensitivity to develop a taste aversion to a novel flavor conditioned by ethanol injections as compared with their unselected HS/NPT founder stock. We have subsequently developed inbred variants of each line. The current experiments established that reduced ethanol-conditioned taste aversion is also seen in the inbred variants, in both males and females. In other experiments, we asked whether HDID mice would ingest sufficient doses of ethanol to lead to a conditioned taste aversion upon retest. Different manipulations were used to elevate consumption of ethanol on initial exposure. Access to increased ethanol concentrations, to multiple tubes of ethanol, and fluid restriction to increase thirst motivation all enhanced initial drinking of ethanol. Each condition led to reduced intake the next day, consistent with a mild conditioned taste aversion. These experiments support the conclusion that one reason contributing to the willingness of HDID mice to drink to the point of intoxication is a genetic insensitivity to the aversive effects of ethanol.