Long-Term Effects of Intermittent Adolescent Alcohol Exposure in Male and Female Rats

Adolescent alcohol exposure persistently alters orbitofrontal cortical encoding of Pavlovian conditional stimulus components in female rats

Exposure to alcohol during adolescence impacts cortical and limbic brain regions undergoing maturation. In rodent models, long-term effects on behavior and neurophysiology have been described after adolescent intermittent ethanol (AIE), especially in males. We hypothesized that AIE in female rats increases conditional approach to a reward-predictive cue and corresponding neuronal activity in the orbitofrontal cortex (OFC) and nucleus accumbens (NAc). We evaluated behavior and neuronal firing after AIE (5 g/kg intragastric) or water (CON) in adult female rats. Both AIE and CON groups expressed a ST phenotype, and AIE marginally increased sign-tracking (ST) and decreased goal-tracking (GT) metrics. NAc neurons exhibited phasic firing patterns to the conditional stimulus (CS), with no differences between groups. In contrast, neuronal firing in the OFC of AIE animals was greater at CS onset and offset than in CON animals. During reward omission, OFC responses to CS offset normalized to CON levels, but enhanced OFC firing to CS onset persisted in AIE. We suggest that the enhanced OFC neural activity observed in AIE rats to the CS could contribute to behavioral inflexibility. Ultimately, AIE persistently impacts the neurocircuitry of reward-motivated behavior in female rats.

Assessing the Influence of Intermittent Alcohol Access on Acrylamide-Induced Neuronal Toxicity in an Experimental Rat Model

Tobacco and alcohol have been identified as health risk behaviors associated with significant unfavorable health consequences, ranking within the list of the top ten causes of mortality and disability-adjusted life years (DALY). The combustion of tobacco leads to the formation of acrylamide (ACR), which is well known for its neurotoxic effects. Similarly, alcohol consumption has also been widely recognized for its neurotoxic effects. Both substances can affect neurons and neuroglia cells through various pathways. This study sought to examine the impacts of co-administration of ACR and intermittent-access ethanol (IAE) consumption over a period of one month. The experimental group received 20 mg/kg of ACR, administered orally, along with IAE of 20% ethanol sessions lasting 24 h, three times per week. The cognitive outcomes were assessed utilizing the elevated plus maze (EPM), which was employed as a means of assessing the capability to learn and remember, the novel object recognition (NOR) test, which was employed to assess recognition memory, and the Y-maze, which was used to explore a new environment and navigate. Additionally, ELISA assays were performed to examine underlying mechanisms, including markers associated with inflammation (NF-κB, PGE2, and TNF-α), apoptosis (Bcl2, Bax, and Caspase-3), and oxidative stress (MDA, catalase, and GSH). These markers were assessed in the brain homogenate as part of the investigation. Furthermore, a histopathological study was conducted. The findings indicated that NF-κB levels increased significantly in the combination of ACR and IAE groups (ACR + IAE) compared to either the ACR-alone or IAE-alone groups. However, parallel changes were observed in TNF-α, PGE2, Bax, Bcl-2, Caspase-3, GSH, and CAT levels when comparing the ACR + IAE group to the ACR-alone group. Comparable alterations were noted between the ACR + IAE treatment and IAE-alone groups in TNF-α, Bcl-2, MDA, GSH, and CAT levels. Moreover, the histopathological analysis revealed significant changes between the ACR + IAE and the ACR- or IAE-alone groups. Regarding memory parameters assessed using tests including EPM, NOR, and Y-maze, considerable changes were observed across all treatment groups as opposed to the control. Surprisingly, there were no notable differences in the NOR and Y-maze tasks between the alone and combination treatment. Further study is necessary to explore the long-term alteration of co-administering ACR and IAE on behavior, memory, and neurotoxicity-related mechanisms, in order to elucidate their combined effects more clearly.

Bacterial lipopolysaccharide forms aggregates with apolipoproteins in male and female rat brains after ethanol binges

Alcohol binge drinking allows the translocation of bacterial lipopolysaccharide (LPS) from the gut to the blood, which activates the peripheral immune system with consequences in neuroinflammation. A possible access/direct signaling of LPS to/in the brain has not yet been described under alcohol abuse conditions. Apolipoproteins are compounds altered by alcohol with high affinity to LPS which may be involved in its transport to the brain or in its elimination. Here, we explored the expression of small components of LPS, in its free form or bound to apolipoproteins, in the brain of female and male rats exposed to alcohol binges. Animals received ethanol oral gavages (3 g/kg every 8 h) for 4 days. LPS or its components (Lipid A and core), LPS-binding protein, corticosterone, lipoproteins (HDL, LDL), apolipoproteins (ApoAI, ApoB, and ApoE), and their receptors were measured in plasma and/or in nonperfused prefrontal cortex (PFC) and cerebellum. Brain LipidA-apolipoprotein aggregates were determined by Western blotting and confirmed by co-immunoprecipitation. In animals exposed to alcohol binges: 1) plasma LPS-binding protein was elevated in both sexes; 2) females showed elevations in plasma ApoAI and corticosterone levels; 3) Lipid A formed aggregates with ApoAI in the female PFC and with ApoB in males, the latter showing Toll-like receptor 4 upregulation in PFC but not females. These results suggest that small bacterial components are present within the brain, forming aggregates with different apolipoproteins, depending on the sex, after alcohol binge intoxications. Results may have implications for the crosstalk between alcohol, LPS, and neuroinflammation.

Recency memory is altered in cocaine-withdrawn adolescent rats: Implication of cortical mTOR signaling

In humans, cocaine abuse during adolescence poses a significant risk for developing cognitive deficits later in life. Among the regions responsible for cognitive processes, the medial prefrontal cortex (mPFC) modulates temporal order information via mechanisms involving the mammalian-target of rapamycin (mTOR)-mediated pathway and protein synthesis regulation. Accordingly, our goal was to study the effect of repeated cocaine exposure during both adolescence and adulthood on temporal memory by studying the mTOR pathway in the mPFC. Adolescent or adult rats underwent repeated cocaine injections for 15 days and, after two weeks of withdrawal, engaged in the temporal order object recognition (TOOR) test. We found that repeated cocaine exposure during adolescence impaired TOOR performance, while control or adult-treated animals showed no impairments. Moreover, activation of the mTOR-S6-eEF2 pathway following the TOOR test was diminished only in the adolescent cocaine-treated group. Notably, inhibition of the mTOR-mediated pathway by rapamycin injection impaired TOOR performance in naïve adolescent and adult animals, revealing this pathway to be a critical component in regulating recency memory. Our data indicate that withdrawal from cocaine exposure impairs recency memory via the dysregulation of protein translation mechanisms, but only when cocaine is administered during adolescence.

Adolescent social housing protects against adult emotional and cognitive deficits and alters the PFC and NAc transcriptome in male and female C57BL/6J mice

Introduction

Adolescence is a critical period in cognitive and emotional development, characterized by high levels of social interaction and increases in risk-taking behavior including binge drinking. Adolescent exposure to social stress and binge ethanol have individually been associated with the development of social, emotional, and cognitive deficits, as well as increased risk for alcohol use disorder. Disruption of cortical development by early life social stress and/or binge drinking may partly underlie these enduring emotional, cognitive, and behavioral effects. The study goal is to implement a novel neighbor housing environment to identify the effects of adolescent neighbor housing and/or binge ethanol drinking on (1) a battery of emotional and cognitive tasks (2) adult ethanol drinking behavior, and (3) the nucleus accumbens and prefrontal cortex transcriptome.

Methods

Adolescent male and female C57BL/6J mice were single or neighbor housed with or without access to intermittent ethanol. One cohort underwent behavioral testing during adulthood to determine social preference, expression of anxiety-like behavior, cognitive performance, and patterns of ethanol intake. The second cohort was sacrificed in late adolescence and brain tissue was used for transcriptomics analysis.

Results

As adults, single housed mice displayed decreased social interaction, deficits in the novel object recognition task, and increased anxiety-like behavior, relative to neighbor-housed mice. There was no effect of housing condition on adolescent or adult ethanol consumption. Adolescent ethanol exposure did not alter adult ethanol intake. Transcriptomics analysis revealed that adolescent housing condition and ethanol exposure resulted in differential expression of genes related to synaptic plasticity in the nucleus accumbens and genes related to methylation, the extracellular matrix and inflammation in the prefrontal cortex.

Discussion

The behavioral results indicate that social interaction during adolescence via the neighbor housing model may protect against emotional, social, and cognitive deficits. In addition, the transcriptomics results suggest that these behavioral alterations may be mediated in part by dysregulation of transcription in the frontal cortex or the nucleus accumbens.

Effects of combined use of alcohol and delta-9-tetrahydrocannibinol on working memory in Long Evans rats

The increase in social acceptance and legalization of cannabis over the last several years is likely to increase the prevalence of its co-use with alcohol. In spite of this, the potential for effects unique to co-use of these drugs, especially in moderate doses, has been studied relatively infrequently. We addressed this in the current study using a laboratory rat model of voluntary drug intake. Periadolescent male and female Long-Evans rats were allowed to orally self-administer ethanol, Δ9-tetrahydrocannibinol (THC), both drugs, or their vehicle controls from postnatal day (P) 30 to P47. They were subsequently trained and tested on an instrumental behavior task that assesses attention, working memory and behavioral flexibility. Similar to previous work, consumption of THC reduced both ethanol and saccharin intake in both sexes. Blood samples taken 14 h following the final self-administration session revealed that females had higher levels of the THC metabolite THC-COOH. There were modest effects of THC on our delayed matching to position (DMTP) task, with females exhibiting reduced performance compared to their control group or male, drug using counterparts. However, there were no significant effects of co-use of ethanol or THC on DMTP performance, and drug effects were also not apparent in the reversal learning phase of the task when non-matching to position was required as the correct response. These findings are consistent with other published studies in rodent models showing that use of these drugs in low to moderate doses does not significantly impact memory or behavioral flexibility following a protracted abstinence period.

The Effect of Very-Long-Chain n-3 Polyunsaturated Fatty Acids in the Central Nervous System and Their Potential Benefits for Treating Alcohol Use Disorder: Reviewing Pre-Clinical and Clinical Data

Alcohol use poses a significant global health concern, leading to serious physical and socioeconomic issues worldwide. The current treatment options for problematic alcohol consumption are limited, leading to the exploration of alternative approaches, such as nutraceuticals. One promising target is very-long-chain n-3 polyunsaturated fatty acids (VLC n-3 PUFAs). This review aims to compile the most relevant pre-clinical and clinical evidence on the effect of VLC n-3 PUFAs on alcohol use disorders and related outcomes. The findings suggest that VLC n-3 PUFAs may alleviate the physiological changes induced by alcohol consumption, including neuroinflammation and neurotransmitter dysregulation. Additionally, they can reduce withdrawal symptoms, improve mood, and reduce stress level, all of which are closely associated with problematic alcohol consumption. However, more research is required to fully understand the precise mechanisms by which VLC n-3 PUFAs exert their function. Furthermore, PUFAs should not be considered a standalone solution, but as a complement to other therapeutic approaches. Although preliminary evidence supports the potential therapeutic effect of VLC n-3 PUFAs on problematic alcohol consumption, additional research is needed to validate these findings and determine the optimal use of PUFAs as part of a comprehensive approach to the treatment of alcohol use disorders.

Effects of combined use of alcohol and delta-9-tetrahydrocannibinol on working memory in Long Evans rats

The increase in social acceptance and legalization of cannabis over the last several years is likely to increase the prevalence of its co-use with alcohol. In spite of this, the potential for effects unique to co-use of these drugs, especially in moderate doses, has been studied relatively infrequently. We addressed this in the current study using a laboratory rat model of voluntary drug intake. Periadolescent male and female Long-Evans rats were allowed to orally self-administer ethanol, Î" 9 -tetrahydrocannibinol (THC), both drugs, or their vehicle controls from postnatal day (P) 30 to P47. They were subsequently trained and tested on an instrumental behavior task that assesses attention, working memory and behavioral flexibility. Similar to previous work, consumption of THC reduced both ethanol and saccharin intake in both sexes. Blood samples taken 14h following the final self-administration session revealed that females had higher levels of the THC metabolite THC-COOH. There were modest effects of THC on our delayed matching to position (DMTP) task, with females exhibiting reduced performance compared to their control group or male, drug using counterparts. However, there were no significant effects of co-use of ethanol or THC on DMTP performance, and drug effects were also not apparent in the reversal learning phase of the task when non-matching to position was required as the correct response. These findings are consistent with other published studies in rodent models showing that use of these drugs in low to moderate doses does not significantly impact memory or behavioral flexibility following a protracted abstinence period.

Adolescent binge ethanol impacts H3K36me3 regulation of synaptic genes

Adolescence is marked in part by the ongoing development of the prefrontal cortex (PFC). Binge ethanol use during this critical stage in neurodevelopment induces significant structural changes to the PFC, as well as cognitive and behavioral deficits that can last into adulthood. Previous studies showed that adolescent binge ethanol causes lasting deficits in working memory, decreases in the expression of chromatin remodeling genes responsible for the methylation of histone 3 lysine 36 (H3K36), and global decreases in H3K36 in the PFC. H3K36me3 is present within the coding region of actively-transcribed genes, and safeguards against aberrant, cryptic transcription by RNA Polymerase II. We hypothesize that altered methylation of H3K36 could play a role in adolescent binge ethanol-induced memory deficits. To investigate this at the molecular level, ethanol (4 g/kg, i.g.) or water was administered intermittently to adolescent mice. RNA-and ChIP-sequencing were then performed within the same tissue to determine gene expression changes and identify genes and loci where H3K36me3 was disrupted by ethanol. We further assessed ethanol-induced changes at the transcription level with differential exon-use and cryptic transcription analysis - a hallmark of decreased H3K36me3. Here, we found ethanol-induced changes to the gene expression and H3K36me3-regulation of synaptic-related genes in all our analyses. Notably, H3K36me3 was differentially trimethylated between ethanol and control conditions at synaptic-related genes, and Snap25 and Cplx1 showed evidence of cryptic transcription in males and females treated with ethanol during adolescence. Our results provide preliminary evidence that ethanol-induced changes to H3K36me3 during adolescent neurodevelopment may be linked to synaptic dysregulation at the transcriptional level, which may explain the reported ethanol-induced changes to PFC synaptic function.

Ethanol-induced conditioned taste aversion and associated neural activation in male rats: Impact of age and adolescent intermittent ethanol exposure

Individuals that initiate alcohol use at younger ages and binge drink during adolescence are more susceptible to developing alcohol use disorder. Adolescents are relatively insensitive to the aversive effects of alcohol and tend to consume significantly more alcohol per occasion than adults, an effect that is conserved in rodent models. Adolescent typical insensitivity to the aversive effects of alcohol may promote greater alcohol intake by attenuating internal cues that curb its consumption. Attenuated sensitivity to the aversive effects of alcohol is also retained into adulthood following protracted abstinence from adolescent intermittent ethanol (AIE) exposure. Despite these effects, much remains unknown regarding the neural contributors. In the present study, we used a conditioned taste aversion (CTA) paradigm to investigate neuronal activation in late-developing forebrain structures of male adolescents and adult cFos-LacZ transgenic rats as well as in AIE adults following consumption of 0.9% sodium chloride previously paired with an intraperitoneal injection of 0, 1.5 or 2.5 g/kg of ethanol. Adults that were non-manipulated or received water exposure during adolescence showed CTA to both ethanol doses, whereas adolescents displayed CTA only to the 2.5 g/kg ethanol dose. Adults who experienced AIE did not show CTA. Adults displayed increased neuronal activation indexed via number of β-galactosidase positive (β-gal+) cells in the prefrontal and insular cortex that was absent in adolescents, whereas adolescents but not adults had a reduced number of β-gal+ cells in the central amygdala. Adults also displayed greater cortical-insular functional connectivity than adolescents as well as insular-amygdalar and prefrontal cortex-accumbens core functional connectivity. Like adolescents, adults previously exposed to AIE displayed reduced prefrontal-insular cortex and prefrontal-accumbal core functional connectivity. Taken together, these results suggest that attenuated sensitivity to the aversive effects of ethanol is related to a loss of an insular-prefrontal cortex-accumbens core circuit.

Repeated Cycles of Binge-Like Ethanol Exposure Induces Neurobehavioral Changes During Short- and Long-Term Withdrawal in Adolescent Female Rats

Alcohol consumption is spread worldwide and can lead to an abuse profile associated with severe health problems. Adolescents are more susceptible to addiction and usually consume ethanol in a binge drinking pattern. This form of consumption can lead to cognitive and emotional disorders, however scarce studies have focused on long-term hazardous effects following withdrawal periods after binge drinking in adolescents. Thus, the present study aims at investigating whether behavioral and cognitive changes persist until mid and late adulthood. Female Wistar rats (9-10 animals/group) received intragastric administration of four cycles of ethanol binge-like pattern (3.0 g/kg/day, 20% w/v; 3 days-on/4 days-off) from 35^th to 58^th days old, followed withdrawal checkpoints 1 day, 30 days, and 60 days. At each checkpoint period, behavioral tests of open field, object recognition test, elevated plus maze, and forced swimming test were performed, and blood and hippocampus were collected for oxidative biochemistry and brain-derived neurotrophic factor (BDNF) levels analysis, respectively. The results demonstrated that adolescent rats exposed to binge drinking displayed anxiogenic- and depressive-like phenotype in early and midadulthood, however, anxiety-like profile persisted until late adulthood. Similarly, short-term memory was impaired in all withdrawal periods analysed, including late adult life. These behavioral data were associated with oxidative damage in midadulthood but not BDNF alterations. Taken together, the present work highlights the long-lasting emotional and cognitive alterations induced by ethanol binge drinking during adolescence, even after a long period of abstinence, which might impact adult life.

Alcohol availability during withdrawal gates the impact of alcohol vapor exposure on responses to alcohol cues

RATIONALE

Chronic intermittent ethanol (CIE) vapor inhalation is a widely used model of alcohol dependence, but the impact of CIE on cue-elicited alcohol seeking is poorly understood.

OBJECTIVE

Here, we assessed the effects of CIE on alcohol-seeking elicited by cues paired with alcohol before or after CIE vapor inhalation.

METHODS

In experiment 1, male and female Long-Evans rats were trained in a discriminative stimulus (DS) task, in which one auditory cue (the DS) predicts the availability of 15% ethanol and a control cue (the NS) predicts no ethanol. Rats then underwent CIE or served as controls. Subsets of each group received access to oral ethanol twice a week during acute withdrawal. After CIE, rats were presented with the DS and NS cues under extinction and retraining conditions to determine whether they would alter their responses to these cues. In experiment 2, rats underwent CIE prior to training in the DS task.

RESULTS

CIE enhanced behavioral responses to cues previously paired with alcohol, but only in rats that received access to alcohol during acute withdrawal. When CIE occurred before task training, male rats were slower to develop cue responses and less likely to enter the alcohol port, even though they had received alcohol during acute withdrawal.

CONCLUSIONS

These results suggest that CIE vapor inhalation alone does not potentiate the motivational value of alcohol cues but that an increase in cue responses requires alcohol experience during acute withdrawal. Furthermore, under some conditions, CIE may disrupt responses to alcohol-paired cues.

Areas of Convergence and Divergence in Adolescent Social Isolation and Binge Drinking: A Review

Adolescence is a critical developmental period characterized by enhanced social interactions, ongoing development of the frontal cortex and maturation of synaptic connections throughout the brain. Adolescents spend more time interacting with peers than any other age group and display heightened reward sensitivity, impulsivity and diminished inhibitory self-control, which contribute to increased risky behaviors, including the initiation and progression of alcohol use. Compared to adults, adolescents are less susceptible to the negative effects of ethanol, but are more susceptible to the negative effects of stress, particularly social stress. Juvenile exposure to social isolation or binge ethanol disrupts synaptic connections, dendritic spine morphology, and myelin remodeling in the frontal cortex. These structural effects may underlie the behavioral and cognitive deficits seen later in life, including social and memory deficits, increased anxiety-like behavior and risk for alcohol use disorders (AUD). Although the alcohol and social stress fields are actively investigating the mechanisms through which these effects occur, significant gaps in our understanding exist, particularly in the intersection of the two fields. This review will highlight the areas of convergence and divergence in the fields of adolescent social stress and ethanol exposure. We will focus on how ethanol exposure or social isolation stress can impact the development of the frontal cortex and lead to lasting behavioral changes in adulthood. We call attention to the need for more mechanistic studies and the inclusion of the evaluation of sex differences in these molecular, structural, and behavioral responses.

Effects of binge drinking and the anti-inflammatory drug indomethacin on spatial memory and cognitive flexibility in mice

In previous research, we found that chronic-intermittent ethanol administration (CIEA), a model of binge drinking, impaired emotional memory in mice, and this impairment was counteracted by the anti-inflammatory drug indomethacin. In the present study, we evaluated the effects of CIEA on spatial memory and cognitive flexibility in adolescent mice of both sexes. Animals were randomly assigned to one of four groups for each sex: SS (saline + saline), SA (saline + alcohol), SI (saline + indomethacin), and AI (alcohol + indomethacin). They were injected with saline, ethanol (3 g/kg) or indomethacin (10 mg/kg) for the first three days of each week, throughout three weeks. 96 h after treatment, subjects learnt a standard water maze task on five consecutive days (4-day training and 1-day probe trial). One day later, mice underwent a reversal task for evaluating spatial cognitive flexibility. Animals receiving alcohol (SA and AI groups) did not differ from controls (SS groups) during the standard task, but animals treated with indomethacin performed better than controls, both in the acquisition trials and the probe trial. During the reversal task, no significant differences between alcohol groups and controls were observed, but the indomethacin group showed significant lower escape latencies than controls. No sex differences were found in either task. In conclusion, binge drinking does not impair spatial memory or spatial cognitive flexibility, while the anti-inflammatory indomethacin improves both, showing that the effects of alcohol and indomethacin on spatial memory (dependent on hippocampus) are different to those they exert on emotional memory (dependent on amygdala).

Kappa opioid receptor blockade in the nucleus accumbens shell prevents sex-dependent alcohol deprivation effect induced by inflammatory pain

ABSTRACT

Pain-induced negative affect reduces life quality of patients by increasing psychiatric comorbidities, including alcohol use disorders (AUDs). Indeed, clinical data suggest pain as a risk factor to suffer AUDs, predicting relapse drinking in abstinent patients. Here, we analyse the impact of pain on alcohol relapse and the role of kappa opioid receptor (KOR) activation in mediating these pain-induced effects because KORs play an important role in pain-driven negative affect and AUD. Female and male Sprague-Dawley rats underwent 2 alcohol intermittent access periods separated by a forced abstinence period. The complete Freund adjuvant model of inflammatory pain was introduced during abstinence, and alcohol intake before and after alcohol reintroduction was assessed. In addition, we used behavioural approaches to measure stress and memory impairment and biochemical assays to measure KOR expression in abstinence and reintroduction periods. Only female CFA-treated rats increased alcohol intake during the reintroduction period. Concomitantly, this group showed enhanced anxiety-like behaviour and increased KOR expression in the nucleus accumbens shell that was developed during abstinence and remained during the reintroduction period. Finally, KOR antagonist norbinaltorphimine was administered in the nucleus accumbens shell during abstinence to prevent a pain-induced alcohol deprivation effect, a phenomenon observed in CFA-female rats. The administration of norbinaltorphimine effectively blocked a pain-induced alcohol deprivation effect in female rats. Our data evidenced that inflammatory pain constitutes a risk factor to increase alcohol consumption during a reintroduction phase only in female rats by the rise and maintenance of stress probably mediated by KOR signalling in the nucleus accumbens.

Methylmercury plus Ethanol Exposure: How Much Does This Combination Affect Emotionality?

Mercury is a heavy metal found in organic and inorganic forms that represents an important toxicant with impact on human health. Mercury can be released in the environment by natural phenoms (i.e., volcanic eruptions), industrial products, waste, or anthropogenic actions (i.e., mining activity). Evidence has pointed to mercury exposure inducing neurological damages related to emotional disturbance, such as anxiety, depression, and insomnia. The mechanisms that underlie these emotional disorders remain poorly understood, although an important role of glutamatergic pathways, alterations in HPA axis, and disturbance in activity of monoamines have been suggested. Ethanol (EtOH) is a psychoactive substance consumed worldwide that induces emotional alterations that have been strongly investigated, and shares common pathophysiological mechanisms with mercury. Concomitant mercury and EtOH intoxication occur in several regions of the world, specially by communities that consume seafood and fish as the principal product of nutrition (i.e., Amazon region). Such affront appears to be more deleterious in critical periods of life, such as the prenatal and adolescence period. Thus, this review aimed to discuss the cellular and behavioral changes displayed by the mercury plus EtOH exposure during adolescence, focused on emotional disorders, to answer the question of whether mercury plus EtOH exposure intensifies depression, anxiety, and insomnia observed by the toxicants in isolation.

The persistent impact of adolescent binge alcohol on adult brain structural, cellular, and behavioral pathology: A role for the neuroimmune system and epigenetics

Adolescence is a critical neurodevelopmental window for maturation of brain structure, neurocircuitry, and glia. This development is sculpted by an individual's unique experiences and genetic background to establish adult level cognitive function and behavioral makeup. Alcohol abuse during adolescence is associated with an increased lifetime risk for developing an alcohol use disorder (AUD). Adolescents participate in heavy, episodic binge drinking that causes persistent changes in neurocircuitry and behavior. These changes may underlie the increased risk for AUD and might also promote cognitive deficits later in life. In this chapter, we have examined research on the persistent effects of adolescent binge-drinking both in humans and in rodent models. These studies implicate roles for neuroimmune signaling as well as epigenetic reprogramming of neurons and glia, which create a vulnerable neuroenvironment. Some of these changes are reversible, giving hope for future treatments to prevent many of the long-term consequences of adolescent alcohol abuse.

The role of sex in the persistent effects of adolescent alcohol exposure on behavior and neurobiology in rodents

Alcohol drinking is often initiated during adolescence, and this frequently escalates to binge drinking. As adolescence is also a period of dynamic neurodevelopment, preclinical evidence has highlighted that some of the consequences of binge drinking can be long lasting with deficits persisting into adulthood in a variety of cognitive-behavioral tasks. However, while the majority of preclinical work to date has been performed in male rodents, the rapid increase in binge drinking in adolescent female humans has re-emphasized the importance of addressing alcohol effects in the context of sex as a biological variable. Here we review several of the consequences of adolescent ethanol exposure in light of sex as a critical biological variable. While some alcohol-induced outcomes, such as non-social approach/avoidance behavior and sleep disruption, are generally consistent across sex, others are variable across sex, such as alcohol drinking, sensitivity to ethanol, social anxiety-like behavior, and induction of proinflammatory markers.

Environmental Enrichment Rescues Endocannabinoid-Dependent Synaptic Plasticity Lost in Young Adult Male Mice after Ethanol Exposure during Adolescence

Binge drinking (BD) is a serious health concern in adolescents as high ethanol (EtOH) consumption can have cognitive sequelae later in life. Remarkably, an enriched environment (EE) in adulthood significantly recovers memory in mice after adolescent BD, and the endocannabinoid, 2-arachydonoyl-glycerol (2-AG), rescues synaptic plasticity and memory impaired in adult rodents upon adolescent EtOH intake. However, the mechanisms by which EE improves memory are unknown. We investigated this in adolescent male C57BL/6J mice exposed to a drinking in the dark (DID) procedure four days per week for a duration of 4 weeks. After DID, the mice were nurtured under an EE for 2 weeks and were subjected to the Barnes Maze Test performed the last 5 days of withdrawal. The EE rescued memory and restored the EtOH-disrupted endocannabinoid (eCB)-dependent excitatory long-term depression at the dentate medial perforant path synapses (MPP-LTD). This recovery was dependent on both the cannabinoid CB1 receptor and group I metabotropic glutamate receptors (mGluRs) and required 2-AG. Also, the EE had a positive effect on mice exposed to water through the transient receptor potential vanilloid 1 (TRPV1) and anandamide (AEA)-dependent MPP long-term potentiation (MPP-LTP). Taken together, EE positively impacts different forms of excitatory synaptic plasticity in water- and EtOH-exposed brains.

Pairing Binge Drinking and a High-Fat Diet in Adolescence Modulates the Inflammatory Effects of Subsequent Alcohol Consumption in Mice

Alcohol binge drinking (BD) and poor nutritional habits are two frequent behaviors among many adolescents that alter gut microbiota in a pro-inflammatory direction. Dysbiotic changes in the gut microbiome are observed after alcohol and high-fat diet (HFD) consumption, even before obesity onset. In this study, we investigate the neuroinflammatory response of adolescent BD when combined with a continuous or intermittent HFD and its effects on adult ethanol consumption by using a self-administration (SA) paradigm in mice. The inflammatory biomarkers IL-6 and CX3CL1 were measured in the striatum 24 h after BD, 3 weeks later and after the ethanol (EtOH) SA. Adolescent BD increased alcohol consumption in the oral SA and caused a greater motivation to seek the substance. Likewise, mice with intermittent access to HFD exhibited higher EtOH consumption, while the opposite effect was found in mice with continuous HFD access. Biochemical analyses showed that after BD and three weeks later, striatal levels of IL-6 and CX3CL1 were increased. In addition, in saline-treated mice, CX3CL1 was increased after continuous access to HFD. After oral SA procedure, striatal IL-6 was increased only in animals exposed to BD and HFD. In addition, striatal CX3CL1 levels were increased in all BD- and HFD-exposed groups. Overall, our findings show that adolescent BD and intermittent HFD increase adult alcohol intake and point to neuroinflammation as an important mechanism modulating this interaction.

Dysregulation of Nociceptin/Orphanin FQ and Dynorphin Systems in the Extended Amygdala of Alcohol Preferring Marchigian Sardinian (msP) Rats

Previous studies have shown that genetically selected Marchigian Sardinian alcohol-preferring (msP) rats consume excessive amounts of ethanol to self-medicate from negative moods and to relieve innate hypersensitivity to stress. This phenotype resembling a subset of alcohol use disorder (AUD) patients, appears to be linked to a dysregulation of the equilibrium between stress and antistress mechanisms in the extended amygdala. Here, comparing water and alcohol exposed msP and Wistar rats we evaluate the transcript expression of the anti-stress opioid-like peptide nociceptin/orphanin FQ (N/OFQ) and its receptor NOP as well as of dynorphin (DYN) and its cognate κ-opioid receptor (KOP). In addition, we measured the transcript levels of corticotropin-releasing factor (CRF), CRF receptor 1 (CRF1R), brain-derived neurotrophic factor (BDNF) and of the tropomyosin receptor kinase B receptor (Trk-B). Results showed an innately up-regulation of the CRFergic system, mediating negative mood and stress responses, as well as an inherent up-regulation of the anti-stress N/OFQ system, both in the amygdala (AMY) and bed nucleus of the stria terminalis (BNST) of msP rats. The up-regulation of this latter system may reflect an attempt to buffer the negative condition elicited by the hyperactivity of pro-stress mechanisms since results showed that voluntary alcohol consumption dampened N/OFQ. Alcohol exposure also reduced the expression of dynorphin and CRF transmissions in the AMY of msP rats. In the BNST, alcohol intake led to a more complex reorganization of these systems increasing receptor transcripts in msP rats, along with an increase of CRF and a decrease of N/OFQ transcripts, respectively. Moreover, mimicking the effects of alcohol in the AMY we observed that the activation of NOP receptor by intracerebroventricular administration of N/OFQ in msP rats caused an increase of BDNF and a decrease of CRF transcripts. Our study indicates that both stress and anti-stress mechanisms are dysregulated in the extended AMY of msP rats. The voluntary alcohol drinking, as well as NOP agonism, have a significant impact on neuropeptidergic systems arrangement, bringing the systems back to normalization.

Sex and Age Effects on Neurobehavioral Toxicity Induced by Binge Alcohol

Historically, most alcohol neurotoxicity studies were conducted in young adult males and focused on chronic intake. There has been a shift towards studying the effects of alcohol on the adolescent brain, due to alcohol consumption during this formative period disrupting the brain's developmental trajectory. Because the most typical pattern of adolescent alcohol intake is heavy episodic (binge) drinking, there has also been a shift towards the study of binge alcohol-induced neurobehavioral toxicity. It has thus become apparent that binge alcohol damages the adolescent brain and there is increasing attention to sex-dependent effects. Significant knowledge gaps remain in our understanding of the effects of binge alcohol on the female brain, however. Moreover, it is unsettling that population-level studies indicate that the prevalence of binge drinking is increasing among American women, particularly those in older age groups. Although study of adolescents has made it apparent that binge alcohol disrupts ongoing brain maturational processes, we know almost nothing about how it impacts the aging brain, as studies of its effects on the aged brain are relatively scarce, and the study of sex-dependent effects is just beginning. Given the rapidly increasing population of older Americans, it is crucial that studies address age-dependent effects of binge alcohol, and given the increase in binge drinking in older women who are at higher risk for cognitive decline relative to men, studies must encompass both sexes. Because adolescence and older age are both characterized by age-typical brain changes, and because binge drinking is the most common pattern of alcohol intake in both age groups, the knowledge that we have amassed on binge alcohol effects on the adolescent brain can inform our study of its effects on the aging brain. In this review, we therefore cover the current state of knowledge of sex and age-dependent effects of binge alcohol, as well as statistical and methodological considerations for studies aimed at addressing them.

Adolescent Alcohol Exposure Produces Protracted Cognitive-Behavioral Impairments in Adult Male and Female Rats

Binge drinking is common in adolescence. Rodent studies modeling adolescent binge drinking find persistent effects on the brain's physiology, including increased expression of neuroimmune genes, impaired neurogenesis, and changes in behavioral flexibility. This study used females and males to investigate the effects of adolescent intermittent ethanol (AIE) on a battery of behaviors assessing spatial navigation using a radial arm water maze, working memory using the Hebb-Williams maze, non-spatial long-term memory using novel object recognition, and dominance using a tube dominance test. Results indicate that AIE impairs adult acquisition in spatial navigational learning with deficits predominantly driven by females. Surprisingly, AIE slowed the transition from random to serial search strategies in both sexes, suggesting AIE impairs flexibility in problem-solving processing. In the Hebb-Williams maze working memory task, adult AIE rats exhibited deficits in problem solving, resulting in more errors across the 12 maze configurations, independent of sex. Conversely, AIE decreased dominance behaviors in female rats, and at 7 months post-alcohol, female AIE rats continued to exhibit deficits in novel object recognition. These results suggest that cognitive-behavioral alterations after adolescent binge drinking persist well into middle age, despite abstinence. Future studies should focus on intervening treatment strategies in both females and males.

Differential alterations of insular cortex excitability after adolescent or adult chronic intermittent ethanol administration in male rats

Adolescent alcohol drinking, primarily in the form of binge-drinking episodes, is a serious public health concern. Binge drinking in laboratory animals has been modeled by a procedure involving chronic intermittent ethanol (CIE) administration, as compared with chronic intermittent water (CIW). The prolonged effects of adolescent binge alcohol exposure in adults, such as high risk of developing alcohol use disorder, are severe but available treatments in the clinic are limited. One reason is the lack of sufficient understanding about the associated neuronal alterations. The involvement of the insular cortex, particularly the anterior agranular insula (AAI), has emerged as a critical region to explain neuronal mechanisms of substance abuse. This study was designed to evaluate the functional output of the AAI by measuring the intrinsic excitability of pyramidal neurons from male rats 2 or 21 days after adolescent or adult CIE treatment. Decreases in intrinsic excitability in AAI pyramidal neurons were detected 21 days, relative to 2 days, after adolescent CIE. Interestingly, the decreased intrinsic excitability in the AAI pyramidal neurons was observed 2 days after adult CIE, compared to adult CIW, but no difference was found between 2 versus 21 days after adult CIE. These data indicate that, although the AAI is influenced within a limited period after adult but not adolescent CIE, neuronal alterations in AAI are affected during the prolonged period of withdrawal from adolescent but not adult CIE. This may explain the prolonged vulnerability to mental disorders of subjects with an alcohol binge history during their adolescent stage.

Sigma-1 antagonism inhibits binge ethanol drinking at adolescence

BACKGROUND

Ethanol use during adolescence is a significant health problem, yet the pharmacological treatments to reduce adolescent binge drinking are scarce. The present study assessed, in male and female adolescent Wistar rats, if the sigma-1 receptor (S1-R) antagonists S1RA or BD-1063 disrupted ethanol drinking.

METHODS

Three times a week, for two weeks, the rats received the S1-R antagonists. Thirty min later they were exposed, for 2 h, to a bottle of 8% or 10 % v/v ethanol. A 24 h, two-bottle, ethanol intake test was conducted after termination of these procedures. A subset of these rats was tested for recognition memory via the novel object recognition test.

RESULTS

The rats given 64 mg/kg S1RA drank, in each binge session, significantly less than vehicle counterparts. Male rats given 4 or 16 mg/kg S1RA drank significantly less than those given 0 mg/kg in session 3 or in session 1 and 2, respectively; whereas female rats given 4 or 16 mg/kg drank significantly less than females given 0 mg/kg in session 2-5 or in sessions 2-6, respectively. Administration of 32 mg/kg, but not of 2 or 8 mg/kg, BD-1063 suppressed, across sessions, ethanol drinking. S1-R antagonism reduced absolute ethanol drinking at the two-bottle choice post-test. Recognition memory was not affected by the ethanol exposure.

CONCLUSIONS

The results indicate that S1-R antagonists may be promising targets to prevent increases in ethanol intake at adolescence. The persistent effect of S1-R antagonism in free-choice drinking suggests that modulation of the S1-R is altering plastic effects associated with ethanol exposure.

Effect of alcohol use on the adolescent brain and behavior

Adolescence is a particularly vulnerable neurodevelopmental period marked by high rates of engagement with risky alcohol use. This review summarizes the cognitive and neural consequences following alcohol use during adolescence from longitudinal design studies in humans and animals. Findings from human adolescent studies suggest that binge drinking and heavy alcohol use is associated with poorer cognitive functioning on a broad range of neuropsychological assessments, including learning, memory, visuospatial functioning, psychomotor speed, attention, executive functioning, and impulsivity. Alcohol use during adolescence is associated with accelerated decreases in gray matter and attenuated increases in white matter volume, and aberrant neural activity during executive functioning, attentional control, and reward sensitivity tasks, when compared to non-drinking adolescents. Animal studies in rodents and non-human primates have replicated human findings, and suggest cognitive and neural consequences of adolescent alcohol use may persist into adulthood. Novel rodent studies demonstrate that adolescent alcohol use may increase reward responsiveness of the dopamine system to alcohol later in life, as well as disrupt adolescent neurogenesis, potentially through neuroinflammation, with long-lasting neural and behavioral effects into adulthood. Larger longitudinal human cognitive and neuroimaging studies with more diverse samples are currently underway which will improve understanding of the impact of polysubstance use, as well as the interactive effects of substance use, physical and mental health, and demographic factors on cognition and neurodevelopment.

Repeated cocaine exposure during adolescence impairs recognition memory in early adulthood: A role for BDNF signaling in the perirhinal cortex

The perirhinal cortex (PrhC) is critical for object recognition memory; however, information regarding the molecular mechanisms underlying this type of memory following repeated exposure to drugs of abuse during adolescence is unknown. To this end, adolescent or adult rats were exposed to cocaine from postnatal day (PND) 28 to PND 42 or PND 63 to PND 77, respectively. Two weeks later, rats were subjected to the cognitive test named Novel Object Recognition (NOR) test. We found that adolescent, but not adult, cocaine exposure caused a significant impairment in the NOR test, independently from changes in the stress response system. In adolescent saline-treated rats, NOR test up-regulated BDNF and its downstream signaling whereas a downregulation of the same pathway was observed in cocaine-treated rats together with a reduction of Arc/Arg3.1 and PSD95 expression, indicating reduced pro-cognitive structural adaptations in the PrhC. Of note, cocaine-treated adult rats correctly performed in the NOR test indicating intact recognition memory mechanisms, despite a significant cocaine-induced reduction of BDNF levels in the PrhC, suggesting that recognition memory is heavily dependent on BDNF during adolescence whereas during adulthood other mechanisms come into play.

Binge-Like, Naloxone-Sensitive, Voluntary Ethanol Intake at Adolescence Is Greater Than at Adulthood, but Does Not Exacerbate Subsequent Two-Bottle Choice Drinking

The present study assessed the effects of ethanol exposure during adolescence or adulthood. We exposed Wistar rats, males or females, to self-administered 8–10% (v/v) ethanol (BINGE group) during the first 2 h of the dark cycle, three times a week (Monday, Wednesday, and Friday) during postnatal days (PDs) 32–54 or 72–94 (adolescent and adults, respectively). During this period, controls were only handled, and a third (IP) condition was given ethanol intraperitoneal administrations, three times a week (Monday, Wednesday, and Friday), at doses that matched those self-administered by the BINGE group. The rats were tested for ethanol intake and preference in a two-bottle (24 h long) choice test, shortly before (PD 30 or 70) and shortly after (PD 56 or 96) exposure to the binge or intraperitoneal protocol; and then tested for free-choice drinking during late adulthood (PDs 120–139) in intermittent two-bottle intake tests. Binge drinking was significantly greater in adolescents vs. adults, and was blocked by naloxone (5.0 mg/kg) administered immediately before the binge session. Mean blood ethanol levels (mg/dl) at termination of binge session 3 were 60.82 ± 22.39. Ethanol exposure at adolescence, but not at adulthood, significantly reduced exploration of an open field-like chamber and significantly increased shelter-seeking behavior in the multivariate concentric square field. The rats that had been initially exposed to ethanol at adolescence drank, during the intake tests conducted at adulthood, significantly more than those that had their first experience with ethanol at adulthood, an effect that was similar among BINGE, IP and control groups. The study indicates that binge ethanol drinking is greater in adolescent that in adults and is associated with heightened ethanol intake at adulthood. Preventing alcohol access to adolescents should reduce the likelihood of problematic alcohol use or alcohol-related consequences.

Emotional memory impairment produced by binge drinking in mice is counteracted by the anti-inflammatory indomethacin

The Binge Drinking (BD) pattern of alcohol consumption, prevalent in adolescents and young adults, has been associated with memory impairment. In addition, evidence shows that alcohol abuse causes neuroinflammation, which may contribute to the brain damage produced by alcohol and explain its cognitive consequences. In this study, we evaluated the effectiveness of the anti-inflammatory indomethacin in counteracting the memory impairment produced by alcohol (ethanol) in adolescent mice of both sexes. Animals were randomly assigned to one of four groups for each sex: SS (saline + saline), SA (saline + alcohol), SI (saline + indomethacin) and AI (alcohol + indomethacin). They were injected acutely (Experiment 1) or chronically intermittent (Experiment 2) with saline, ethanol (3 g/kg) and indomethacin (10 mg/kg). All subjects were evaluated in an inhibitory avoidance task 96 h after treatment. With acute administration, SA groups showed significantly lower Test latencies than SS groups, while AI groups had similar latencies to controls. The chronic-intermittent administration of alcohol, an animal model of BD, produced significant emotional memory impairment -blocking learning in males- which was counteracted by indomethacin, as the AI groups had similar latencies to the SS groups. No significant differences were observed in locomotor activity or analgesia. In conclusion, alcohol BD (one or several episodes) impairs emotional memory in mice. This impairment is not secondary to the effects of alcohol BD on locomotor activity or pain sensitivity, and it is counteracted by indomethacin. Therefore, the memory impairment produced by alcohol BD seems to be mediated, in part, by neuroinflammatory processes. These findings open a window for new treatments for alcohol use disorders.

The effects of multiple early life stressors on adolescent alcohol consumption

Alcohol use disorder is pervasive and effects the health of millions. Identifying factors such as early life stress that contribute to the development of alcohol use disorder is therefore critical, especially those that contribute to adolescent drinking, a strong predictor of AUD development. The majority of prior studies have examined early life effects on adult drinking, but have not studied intake during adolescence, and no prior studies have examined how the effects of multiple stressors may be additive. Therefore, this study determined if experiencing individual or multiple stressors increases adolescent alcohol intake. Male Long Evans rats underwent either early or late maternal separation (postnatal day 2-9 or 13-20), early adolescent social defeat (PND 30-40), both, or neither. All rats were then given two-hour access to alcohol, and voluntary intake assessed daily in late adolescence (PND 41-51). In adulthood, sensitivity to alcohol's sedative effects was assessed using loss and regain of righting reflex tests. Results indicate that experiencing maternal separation (at either time point) or social defeat increased adolescent alcohol consumption, but experiencing the combined stressors did not, and that no stressor significantly affected body weight during adolescence or loss and regain of righting reflex in adulthood. Overall, this pattern of effects suggests that experiencing any individual early life stressor may increase adolescent alcohol intake, in agreement with prior literature, but that the combined effects of multiple early life stressors may be more complicated.

The effects of social instability stress and subsequent ethanol consumption in adolescence on brain and behavioral development in male rats

Excessive drinking in adolescence continues to be a problem, and almost a quarter of young Canadians have reported consuming five or more alcoholic drinks in one occasion in recent surveys. The consequences of such drinking may be more pronounced when commenced in adolescence, given the ongoing brain development during this period of life. Here, we investigated the consequences of 3 weeks' intermittent access to ethanol in mid-adolescence to early adulthood in rats, and the extent to which a stress history moderated the negative consequences of ethanol access. In experiment 1, male rats that underwent adolescent social instability stress (SS; daily 1 h isolation + return to unfamiliar cage partner every day from postnatal day [PND] 30-45) did not differ from control (CTL) rats in intake of 10% ethanol sweetened with 0.1% saccharin (access period; PND 47-66). Ethanol drinking reduced proteins relevant for synaptic plasticity (αCaMKII, βCaMKII, and PSD-95) in the dorsal hippocampus, and in CTL rats only in the prefrontal cortex (αCaMKII and PSD 95), attenuating the difference between CTL and SS rats in the water-drinking group. In experiment 2, ethanol also attenuated the difference between SS and CTL rats in a social interaction test by reducing social interaction in SS rats; CTL rats, however, had a higher intake of ethanol than did SS rats during the access period. Ethanol drinking reduced baseline and fear recall recovery concentrations of corticosterone relative to those exposed only to water, although there was no effect of either ethanol or stress history on fear conditioning. Ethanol drinking did not influence intake after 9 days of withdrawal; however, ethanol-naïve SS rats drank more than did CTL rats when given a 24-h access in adulthood. These results reveal a complex relationship between stress history and ethanol intake in adolescence on outcomes in adulthood.

Intermittent ethanol exposure during adolescence impairs cannabinoid type 1 receptor-dependent long-term depression and recognition memory in adult mice

Binge drinking is a significant problem in adolescent populations, and because of the reciprocal interactions between ethanol (EtOH) consumption and the endocannabinoid (eCB) system, we sought to determine if adolescent EtOH intake altered the localization and function of the cannabinoid 1 (CB1) receptors in the adult brain. Adolescent mice were exposed to a 4-day-per week drinking in the dark (DID) procedure for a total of 4 weeks and then tested after a 2-week withdrawal period. Field excitatory postsynaptic potentials (fEPSPs), evoked by medial perforant path (MPP) stimulation in the dentate gyrus molecular layer (DGML), were significantly smaller. Furthermore, unlike control animals, CB1 receptor activation did not depress fEPSPs in the EtOH-exposed animals. We also examined a form of excitatory long-term depression that is dependent on CB1 receptors (eCB-eLTD) and found that it was completely lacking in the animals that consumed EtOH during adolescence. Histological analyses indicated that adolescent EtOH intake significantly reduced the CB1 receptor distribution and proportion of immunopositive excitatory synaptic terminals in the medial DGML. Furthermore, there was decreased binding of [35S]guanosine-5*-O-(3-thiotriphosphate) ([35S] GTPγS) and the guanine nucleotide-binding (G) protein Gαi2 subunit in the EtOH-exposed animals. Associated with this, there was a significant increase in monoacylglycerol lipase (MAGL) mRNA and protein in the hippocampus of EtOH-exposed animals. Conversely, deficits in eCB-eLTD and recognition memory could be rescued by inhibiting MAGL with JZL184. These findings indicate that repeated exposure to EtOH during adolescence leads to long-term deficits in CB1 receptor expression, eCB-eLTD, and reduced recognition memory, but that these functional deficits can be restored by treatments that increase endogenous 2-arachidonoylglycerol.

Emotional Reactivity to Incentive Downshift in Adult Rats Exposed to Binge-Like Ethanol Exposure During Adolescence

Alcohol use in adolescents is often characterized by binge-like ethanol consumption pattern, which is associated with long-term health consequences and even with important harms to his developing brain. Among this, ethanol exposure induces long-lasting alterations in anxiety-related neurobiological systems such as corticotropin releasing factor (CRF) or melanocortin system (MC). Recently, it has been demonstrated that adult rats exposed to adolescent intermittent ethanol (AIE) exposure exhibited anxiogenic-like behavior. Given that it has been demonstrated that negative affective state is relevant to development of addictive behavior, it is tempting to suggest that increased risk of adult abusive alcohol use exhibited in rats exposed to ethanol during adolescence may be related with differences in anxiety-related behavior. We conducted a study investigating the emotional reactivity after a reward devaluation (12-to-1 pellet or 32-to-4% sucrose downshift) in adult rats exposed to binge-like ethanol exposure during adolescence. For this aim, adolescent Sprague-Dawley rats were treated with ethanol (2.5 g/kg ip; AIE) or saline (AIS) for 2 consecutive days at 48-h intervals over a 14-day period (PND30-PND43). Following 25 free-ethanol days, adult rats were trained in consummatory and instrumental successive negative contrast task (cSNC and iSNC). Our data shows that both AIE and AIS groups exhibited suppression of the consummatory and instrumental behavior after reward devaluation relative to unshifthed control. Also, adult rats exposed to alcohol during adolescence exhibited a particularly strong negative affective state (lower sucrose consumption) with regards to the AIS group in the cSNC. This data demonstrated that adolescent binge-like ethanol exposure might trigger a greater emotional reactivity following incentive downshift, which might be linked to higher vulnerability to substance use disorder.