Only male mice show sensitization of handling-induced convulsions across repeated ethanol withdrawal cycles

Stress and gonadal steroid influences on alcohol drinking and withdrawal, with focus on animal models in females

Sexually dimorphic effects of alcohol, following binge drinking, chronic intoxication, and withdrawal, are documented at the level of the transcriptome and in behavioral and physiological responses. The purpose of the current review is to update and to expand upon contributions of the endocrine system to alcohol drinking and withdrawal in females, with a focus on animal models. Steroids important in the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axes, the reciprocal interactions between these axes, the effects of chronic alcohol use on steroid levels, and the genomic and rapid membrane-associated effects of steroids and neurosteroids in models of alcohol drinking and withdrawal are described. Importantly, comparison between males and females highlight some divergent effects of sex- and stress-steroids on alcohol drinking- and withdrawal-related behaviors, and the distinct differences in response emphasize the importance of considering sex in the development of novel pharmacotherapies for the treatment of alcohol use disorder.

Sex difference in alcohol withdrawal syndrome: a scoping review of clinical studies

Background

We conducted a review of all studies comparing clinical aspects of alcohol withdrawal syndrome (AWS) between men and women.

Methods

Five databases (PubMed, Cochrane, EMBASE, Scopus and Clinical Trials) were searched for clinical studies using the keywords "alcohol withdrawal syndrome" or "delirium tremens" limited to "sex" or "gender" or "sex difference" or "gender difference." The search was conducted on May 19, 2023. Two reviewers selected studies including both male and female patients with AWS, and they compared males and females in type of AWS symptoms, clinical course, complications, and treatment outcome.

Results

Thirty-five observational studies were included with a total of 318,730 participants of which 75,346 had AWS. In twenty of the studies, the number of patients presenting with or developing AWS was separated by sex, resulting in a total of 8,159 (12.5%) female patients and a total of 56,928 (87.5%) male patients. Despite inconsistent results, males were more likely than females to develop complicated AWS [delirium tremens (DT) and AW seizures, collective DT in Males vs. females: 1,792 (85.4%) vs. 307 (14.6%), and collective seizures in males vs. females: 294 (78%) vs. 82 (22%)]. The rates of ICU admissions and hospital length of stay did not show sex differences. Although variable across studies, compared to females, males received benzodiazepine treatment at higher frequency and dose. One study reported that the time from first hospitalization for AWS to death was approximately 1.5 years shorter for males and males had higher mortality rate [19.5% (197/1,016)] compared to females [16% (26/163)].

Conclusion

Despite the significant heterogeneity of the studies selected and the lack of a focus on investigating potential sex differences, this review of clinical studies on AWS suggests that men and women exhibit different AWS manifestations. Large-scale studies focusing specifically on investigating sex difference in AWS are needed.

Behavioral and biochemical effects of alcohol withdrawal in female C3H/HeNRj and C57BL/6JRj mice

Background

Alcohol use disorder (AUD) is a major problem of our society and is often characterized and worsened by relapse. Prolonged alcohol exposure leads to numerous biochemical alterations that, upon cessation of alcohol intake, cause an array of immediate and lasting withdrawal symptoms. Acute withdrawal and neuroinflammation can be harmful in themselves, and lasting withdrawal symptoms contribute to relapse. Here, we conducted an initial feasibility study assessing several behavioral and neurochemical factors in female C3H/HeNRj (C3H) and C57BL/6JRj (B6) mice to determine which strain showed the clearest alcohol withdrawal symptoms during long-term abstinence and neurochemical alterations following re-exposure.

Methods

Female C3H and B6 mice (n = 12 per group/strain) were intermittently exposed to alcohol-containing or control liquid diets for 3 weeks. Acute and prolonged withdrawal symptoms were assessed over a period of 3 weeks using a battery of behavioral test, comprised of alcohol self-administration, anhedonia, hyperalgesia, anxiety-like and depressive-like disturbances. Brain inflammation was measured by multiplex cytokine assay. Monoamine levels in the hippocampus and striatum, as well as exploratory analyses of cations levels in the cerebellum, were assessed by High-Performance Liquid Chromatography (HPLC).

Results

Both C3H and B6 alcohol-exposed mice displayed decreased saccharin intake or preference and higher stress levels assessed by ultrasonic vocalizations (USVs) recordings. B6 but not C3H alcohol-exposed mice also exhibited a slower decline of alcohol oral self-administration (OSA), hyperalgesia, elevated brain TNF-α and elevated serotonin turnover.

Conclusion

Our findings highlight the suitability of the B6 strain to study the behavioral and neurochemical alterations caused by alcohol withdrawal and the potential efficacy of experimental treatments, not only in early detoxification, but also in prolonged abstinence. The feasibility of these assays is important because long-lasting withdrawal symptoms are often the main cause of relapse in alcohol-dependent patients.

Research Needs for Inpatient Management of Severe Alcohol Withdrawal Syndrome: An Official American Thoracic Society Research Statement

Background: Severe alcohol withdrawal syndrome (SAWS) is highly morbid, costly, and common among hospitalized patients, yet minimal evidence exists to guide inpatient management. Research needs in this field are broad, spanning the translational science spectrum. Goals: This research statement aims to describe what is known about SAWS, identify knowledge gaps, and offer recommendations for research in each domain of the Institute of Medicine T0-T4 continuum to advance the care of hospitalized patients who experience SAWS. Methods: Clinicians and researchers with unique and complementary expertise in basic, clinical, and implementation research related to unhealthy alcohol consumption and alcohol withdrawal were invited to participate in a workshop at the American Thoracic Society 2019 International Conference. The committee was subdivided into four groups on the basis of interest and expertise: T0-T1 (basic science research with translation to humans), T2 (research translating to patients), T3 (research translating to clinical practice), and T4 (research translating to communities). A medical librarian conducted a pragmatic literature search to facilitate this work, and committee members reviewed and supplemented the resulting evidence, identifying key knowledge gaps. Results: The committee identified several investigative opportunities to advance the care of patients with SAWS in each domain of the translational science spectrum. Major themes included 1) the need to investigate non-γ-aminobutyric acid pathways for alcohol withdrawal syndrome treatment; 2) harnessing retrospective and electronic health record data to identify risk factors and create objective severity scoring systems, particularly for acutely ill patients with SAWS; 3) the need for more robust comparative-effectiveness data to identify optimal SAWS treatment strategies; and 4) recommendations to accelerate implementation of effective treatments into practice. Conclusions: The dearth of evidence supporting management decisions for hospitalized patients with SAWS, many of whom require critical care, represents both a call to action and an opportunity for the American Thoracic Society and larger scientific communities to improve care for a vulnerable patient population. This report highlights basic, clinical, and implementation research that diverse experts agree will have the greatest impact on improving care for hospitalized patients with SAWS.

Effects of Multiple Detoxifications on Withdrawal Symptoms, Psychiatric Distress and Alcohol-Craving in Patients with an Alcohol Use Disorder

Previous studies have shown an association between the number of withdrawal attempts and increased severity of withdrawal symptoms in patients with an alcohol use disorder (AUD). An underlying allostatic neuroadaptive response may negatively affect the withdrawal pathology after alcohol discontinuation. The objective of the present research is to examine the intensification of psychiatric distress, craving, and post-detoxification drinking outcomes, which may result from these neurobehavioral alternations. Fifty-two AUD inpatients were divided into two groups: <2 previous detoxifications and ≥2 previous detoxifications. Patients completed the Dutch version of the Severity of Withdrawal Scale (SWS), Depression Anxiety Stress Scales (DASS-21), VAS Craving, and Desires for Alcohol Questionnaire (DAQ). Linear mixed effects models were applied, controlling for the number of drinks consumed in the past 30 days and alcohol drinking history (years). Patients who had undergone ≥2 detoxifications reported statistically significantly higher scores on SWS withdrawal and DASS psychiatric symptoms. Also, craving patterns were different between groups, as shown by a statistically significant interaction effect for VAS craving for the time of day factor (morning vs. evening). No statistically significant group differences were found for DAQ scores and post-detoxification drinking outcomes. Due to relatively low 1-month follow-up rates our power was limited to detect such a difference. The present study contributes to the existing body of evidence that multiple detoxifications are associated with aggravated withdrawal/psychiatric pathology, and distinct diurnal patterns of VAS craving. Several clinical implications are discussed and alternative strategies are provided to manage repeated cycles of detoxifications.

Sex Differences in the Epilepsies and Associated Comorbidities: Implications for Use and Development of Pharmacotherapies

The epilepsies are common neurologic disorders characterized by spontaneous recurrent seizures. Boys, girls, men, and women of all ages are affected by epilepsy and, in many cases, by associated comorbidities as well. The primary courses of treatment are pharmacological, dietary, and/or surgical, depending on several factors, including the areas of the brain affected and the severity of the epilepsy. There is a growing appreciation that sex differences in underlying brain function and in the neurobiology of epilepsy are important factors that should be accounted for in the design and development of new therapies. In this review, we discuss the current knowledge on sex differences in epilepsy and associated comorbidities, with emphasis on those aspects most informative for the development of new pharmacotherapies. Particular focus is placed on sex differences in the prevalence and presentation of various focal and generalized epilepsies; psychiatric, cognitive, and physiologic comorbidities; catamenial epilepsy in women; sex differences in brain development; the neural actions of sex and stress hormones and their metabolites; and cellular mechanisms, including brain-derived neurotrophic factor signaling and neuronal-glial interactions. Further attention placed on potential sex differences in epilepsies, comorbidities, and drug effects will enhance therapeutic options and efficacy for all patients with epilepsy. SIGNIFICANCE STATEMENT: Epilepsy is a common neurological disorder that often presents together with various comorbidities. The features of epilepsy and seizure activity as well as comorbid afflictions can vary between men and women. In this review, we discuss sex differences in types of epilepsies, associated comorbidities, pathophysiological mechanisms, and antiepileptic drug efficacy in both clinical patient populations and preclinical animal models.

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.

Biological intersection of sex, age, and environment in the corticotropin releasing factor (CRF) system and alcohol

The neuropeptide corticotropin-releasing factor (CRF) is critical in neural circuit function and behavior, particularly in the context of stress, anxiety, and addiction. Despite a wealth of preclinical evidence for the efficacy of CRF receptor 1 antagonists in reducing behavioral pathology associated with alcohol exposure, several clinical trials have had disappointing outcomes, possibly due to an underappreciation of the role of biological variables. Although he National Institutes of Health (NIH) now mandate the inclusion of sex as a biological variable in all clinical and preclinical research, the current state of knowledge in this area is based almost entirely on evidence from male subjects. Additionally, the influence of biological variables other than sex has received even less attention in the context of neuropeptide signaling. Age (particularly adolescent development) and housing conditions have been shown to affect CRF signaling and voluntary alcohol intake, and the interaction between these biological variables is particularly relevant to the role of the CRF system in the vulnerability or resilience to the development of alcohol use disorder (AUD). Going forward, it will be important to include careful consideration of biological variables in experimental design, reporting, and interpretation. As new research uncovers conditions in which sex, age, and environment play major roles in physiological and/or pathological processes, our understanding of the complex interaction between relevant biological variables and critical signaling pathways like the CRF system in the cellular and behavioral consequences of alcohol exposure will continue to expand ultimately improving the ability of preclinical research to translate to the clinic. This article is part of the special issue on Neuropeptides.

Genotype Differences in Sensitivity to the Anticonvulsant Effect of the Synthetic Neurosteroid Ganaxolone during Chronic Ethanol Withdrawal

Sensitivity to anticonvulsant effects of the γ-aminobutyric acid_A receptor-active neurosteroid allopregnanolone (ALLO) during ethanol withdrawal varies across genotypes, with high sensitivity in genotypes with mild withdrawal and low sensitivity in genotypes with high withdrawal. The present studies determined whether the resistance to ALLO during withdrawal in mouse genotypes with high handling-induced convulsions (HICs) during withdrawal could be overcome with use of ganaxolone (GAN), the metabolically stable derivative of ALLO. In separate studies, male and female Withdrawal Seizure-Prone (WSP-1) and DBA/2J (D2) mice were exposed to air (controls) or 72-h ethanol vapor and then were scored for HICs during withdrawal (hourly for the first 12 h, then at hours 24 and 25). After the HIC scoring at hours 5 and 9, mice were injected with 10 mg/kg GAN or vehicle. Area under the HIC curve (AUC) for hours 5-12 was analyzed. In control WSP-1 mice, GAN significantly reduced AUC by 52% (males) and 63% (females), with effects that were absent or substantially reduced during withdrawal. In contrast, GAN significantly reduced AUC in both control and ethanol-withdrawing male and female D2 mice. AUC was decreased by 81% (males) and 70% (females) in controls and by 35% (males) and 21% (females) during withdrawal. The significant anticonvulsant effect of GAN during withdrawal in D2 but not WSP-1 mice suggests that different mechanisms may contribute to ALLO insensitivity during withdrawal in these two genotypes. Importantly, the results in D2 mice suggest that GAN may be a useful treatment for ethanol withdrawal-induced seizures.

“Not Everything That Shakes Is a Seizure”: Making the Determination of Test Article–Induced Convulsions in Toxicology Studies

Spontaneous unexpected events occasionally develop during the course of rodent preclinical toxicology studies. The presentation of serious adverse events on animal studies may require notification of these events to the Food and Drug Administration if the events are most likely the direct result of test article administration. Classical conditioning of emotional responses may occur over the course of a repeat-dose study and clinical observation calls of “convulsions” are reported to the study director and/or staff veterinarians. In the current heightened environment of most research laboratories related to general animal welfare issues, it is imperative to have an action plan that will help to elucidate the potential origins of these motor events. We provide 10 factors that should be considered to help the study director determine the most likely cause of these motor attacks as being organic or psychogenic in origin.

Effects of Withdrawal from Chronic Intermittent Ethanol Exposure on Sleep Characteristics of Female and Male Mice

BACKGROUND

Sleep disruptions are an important consequence of alcohol use disorders. There is a dearth of preclinical studies examining sex differences in sleep patterns associated with ethanol (EtOH) dependence despite documented sex differences in alcohol-related behaviors and withdrawal symptoms. The purpose of this study was to investigate the effects of chronic intermittent EtOH on sleep characteristics in female and male mice.

METHODS

Female and male C57BL6/J mice had access to EtOH/water 2-bottle choice (2BC) 2 h/d for 3 weeks followed by exposure to EtOH vapor (vapor-2BC) or air for 5 cycles of 4 days. An additional group never experienced EtOH (naïve). Mice were implanted with electroencephalographic (EEG) electrodes, and vigilance states were recorded across 24 hours on the fourth day of withdrawal. The amounts of wakefulness, slow-wave sleep (SWS), and rapid eye movement sleep were calculated, and spectral analysis was performed by fast Fourier transformation.

RESULTS

Overall, vapor-2BC mice showed a decrease in the amount of SWS 4 days into withdrawal as well as a decrease in the power density of slow waves, indicating disruptions in both the amount and quality of sleep in EtOH-dependent mice. This was associated with a decrease in duration and an increase in number of SWS episodes in males and an increase in latency to sleep in females.

CONCLUSIONS

Our results revealed overall deficits in sleep regulation in EtOH-dependent mice of both sexes. Female mice appeared to be more affected with regard to the triggering of sleep, while male mice appeared more sensitive to disruptions in the maintenance of sleep.

Sex differences in the behavioral sequelae of chronic ethanol exposure

Rates of alcohol use disorders (AUDs) differ between men and women, and there is also marked variation between sexes in the effects of acute and chronic alcohol. In parallel to observations in humans, prior studies in rodents have described male/female differences across a range of ethanol-related behaviors, including ethanol drinking. Nonetheless, there remain gaps in our knowledge of the role of sex in moderating the effects of ethanol, particularly in models of chronic ethanol exposure. The goal of the current study was to assess various behavioral sequelae of exposing female C57BL/6J mice to chronic intermittent ethanol (CIE) via ethanol vapors. Following four weeks of CIE exposure, adult male and female mice were compared for ethanol drinking in a two-bottle paradigm, for sensitivity to acute ethanol intoxication (via loss of righting reflex [LORR]) and for anxiety-like behaviors in the novelty-suppressed feeding and marble burying assays. Next, adult and adolescent females were tested on two different two-bottle drinking preparations (fixed or escalating ethanol concentration) after CIE. Results showed that males and females exhibited significantly blunted ethanol-induced LORR following CIE, whereas only males showed increased anxiety-like behavior after CIE. Increased ethanol drinking after CIE was also specific to males, but high baseline drinking in females may have occluded detection of a CIE-induced effect. The failure to observe elevated drinking in females in response to CIE was also seen in females exposed to CIE during adolescence, regardless of whether a fixed or escalating ethanol-concentration two-bottle procedure was employed. Collectively, these data add to the literature on sex differences in ethanol-related behaviors and provide a foundation for future studies examining how the neural consequences of CIE might differ between males and females.

Sex Differences in Animal Models: Focus on Addiction

The purpose of this review is to discuss ways to think about and study sex differences in preclinical animal models. We use the framework of addiction, in which animal models have excellent face and construct validity, to illustrate the importance of considering sex differences. There are four types of sex differences: qualitative, quantitative, population, and mechanistic. A better understanding of the ways males and females can differ will help scientists design experiments to characterize better the presence or absence of sex differences in new phenomena that they are investigating. We have outlined major quantitative, population, and mechanistic sex differences in the addiction domain using a heuristic framework of the three established stages of the addiction cycle: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Female rats, in general, acquire the self-administration of drugs and alcohol more rapidly, escalate their drug taking with extended access more rapidly, show more motivational withdrawal, and (where tested in animal models of "craving") show greater reinstatement. The one exception is that female rats show less motivational withdrawal to alcohol. The bases for these quantitative sex differences appear to be both organizational, in that estradiol-treated neonatal animals show the male phenotype, and activational, in that the female phenotype depends on the effects of gonadal hormones. In animals, differences within the estrous cycle can be observed but are relatively minor. Such hormonal effects seem to be most prevalent during the acquisition of drug taking and less influential once compulsive drug taking is established and are linked largely to progesterone and estradiol. This review emphasizes not only significant differences in the phenotypes of females and males in the domain of addiction but emphasizes the paucity of data to date in our understanding of those differences.

Toll-like Receptors in the Vascular System: Sensing the Dangers Within

Toll-like receptors (TLRs) are components of the innate immune system that respond to exogenous infectious ligands (pathogen-associated molecular patterns, PAMPs) and endogenous molecules that are released during host tissue injury/death (damage-associated molecular patterns, DAMPs). Interaction of TLRs with their ligands leads to activation of downstream signaling pathways that induce an immune response by producing inflammatory cytokines, type I interferons (IFN), and other inflammatory mediators. TLR activation affects vascular function and remodeling, and these molecular events prime antigen-specific adaptive immune responses. Despite the presence of TLRs in vascular cells, the exact mechanisms whereby TLR signaling affects the function of vascular tissues are largely unknown. Cardiovascular diseases are considered chronic inflammatory conditions, and accumulating data show that TLRs and the innate immune system play a determinant role in the initiation and development of cardiovascular diseases. This evidence unfolds a possibility that targeting TLRs and the innate immune system may be a novel therapeutic goal for these conditions. TLR inhibitors and agonists are already in clinical trials for inflammatory conditions such as asthma, cancer, and autoimmune diseases, but their study in the context of cardiovascular diseases is in its infancy. In this article, we review the current knowledge of TLR signaling in the cardiovascular system with an emphasis on atherosclerosis, hypertension, and cerebrovascular injury. Furthermore, we address the therapeutic potential of TLR as pharmacological targets in cardiovascular disease and consider intriguing research questions for future study.

Females uniquely vulnerable to alcohol-induced neurotoxicity show altered glucocorticoid signaling

Women are more sensitive to the harmful effects of alcohol (EtOH) abuse than men, yet the underlying mechanisms remain poorly understood. Previous gene expression analysis of the medial prefrontal cortex (mPFC) following a chronic intoxication paradigm using continuous 72 h vapor inhalation found that females, but not males, exhibit an inflammatory response at peak withdrawal that is associated with cell damage. Given that glucocorticoids can function as anti-inflammatories, are known to increase with EtOH exposure, and influence neurotoxicity, we hypothesized that males and females may exhibit an altered corticosterone (CORT) response following chronic intoxication. Analysis of serum CORT levels revealed the expected increase during withdrawal with no difference between males and females, while control males but not females exhibited higher CORT concentrations than naive animals. Glucocorticoid signaling characterized using focused qPCR arrays identified a sexually dimorphic response in the mPFC during withdrawal, particularly among astrocyte-enriched genes. These genes include aquaporin-1 (Aqp1), sphingosine kinase 1 (Sphk1) and connective tissue growth factor (Ctgf); genes associated with inflammatory signaling, and tissue damage and repair. Bioinformatic analysis also revealed activation of inflammatory signaling and cell death pathways in females. Confirmation studies showed that female mice exhibited significant neuronal degeneration within the anterior cingulate cortex (ACC). By contrast, EtOH exposure lead to a significant reduction in cell death in males. Thus, distinct glucocorticoid signaling pathways are associated with sexually dimorphic neurotoxicity, suggesting one mechanism by which EtOH-exposed females are particularly vulnerable to the damaging effects of alcohol in the CNS.

Estrogen-IGF-1 interactions in neuroprotection: ischemic stroke as a case study

The steroid hormone 17b-estradiol and the peptide hormone insulin-like growth factor (IGF)-1 independently exert neuroprotective actions in neurologic diseases such as stroke. Only a few studies have directly addressed the interaction between the two hormone systems, however, there is a large literature that indicates potentially greater interactions between the 17b-estradiol and IGF-1 systems. The present review focuses on key issues related to this interaction including IGF-1 and sex differences and common activation of second messenger systems. Using ischemic stroke as a case study, this review also focuses on independent and cooperative actions of estrogen and IGF-1 on neuroprotection, blood brain barrier integrity, angiogenesis, inflammation and post-stroke epilepsy. Finally, the review also focuses on the astrocyte, a key mediator of post stroke repair, as a local source of 17b-estradiol and IGF-1. This review thus highlights areas where significant new research is needed to clarify the interactions between these two neuroprotectants.

Environmental stressors influence limited-access ethanol consumption by C57BL/6J mice in a sex-dependent manner

Exposure to stress contributes to ethanol consumption in humans, but it produces inconsistent effects on ethanol drinking in rodent models. Therefore, the present study examined the influence of different stressors (restraint, tail suspension, predator odor, foot shock, and tail pinch) on 2-h access to water and 10% ethanol by male and female C57BL/6J mice and determined whether there were sex-dependent differences in response to stress. Plasma corticosterone (CORT) and allopregnanolone (ALLO) were assessed as indexes of hypothalamic-pituitary-adrenal axis activity and of endogenous neurosteroid levels, respectively, following restraint, tail suspension, and predator odor. These stressors increased plasma CORT and ALLO levels, and produced a greater increase in CORT and ALLO levels in females versus males. Ethanol intake was decreased following restraint, tail suspension, foot shock, and tail pinch in both sexes, with stressor-related differences in the duration of the suppression. Predator odor significantly increased ethanol intake on the following two days in females and on the second day after stress in males. Notably, there was a significant positive correlation between CORT levels immediately after predator odor stress and ethanol intake on the following day. In summary, the type of stressor influenced ethanol consumption, with subtle sex differences in the magnitude and persistence of the effect. These findings are the first to demonstrate that a single, acute exposure to restraint, tail suspension, and predator odor stress increased plasma CORT and ALLO levels in animals with a history of ethanol consumption and that female mice were more responsive than males to the ability of stress to increase CORT and ALLO levels as well as to increase ethanol intake following predator odor stress. Because predator odor stress is a model of post-traumatic stress disorder (PTSD), the present sex differences have important implications for preclinical studies modeling the comorbidity of PTSD and alcohol use disorders.

Sex Differences in Ethanol's Anxiolytic Effect and Chronic Ethanol Withdrawal Severity in Mice with a Null Mutation of the 5α-Reductase Type 1 Gene

Manipulation of endogenous levels of the GABAergic neurosteroid allopregnanolone alters sensitivity to some effects of ethanol. Chronic ethanol withdrawal decreases activity and expression of 5α-reductase-1, an important enzyme in allopregnanolone biosynthesis encoded by the 5α-reductase-1 gene (Srd5a1). The present studies examined the impact of Srd5a1 deletion in male and female mice on several acute effects of ethanol and on chronic ethanol withdrawal severity. Genotype and sex did not differentially alter ethanol-induced hypothermia, ataxia, hypnosis, or metabolism, but ethanol withdrawal was significantly lower in female versus male mice. On the elevated plus maze, deletion of the Srd5a1 gene significantly decreased ethanol's effect on total entries versus wildtype (WT) mice and significantly decreased ethanol's anxiolytic effect in female knockout (KO) versus WT mice. The limited sex differences in the ability of Srd5a1 genotype to modulate select ethanol effects may reflect an interaction between developmental compensations to deletion of the Srd5a1 gene with sex hormones and levels of endogenous neurosteroids.

Voluntary wheel running attenuates ethanol withdrawal-induced increases in seizure susceptibility in male and female rats

We recently found that voluntary wheel running attenuated ethanol withdrawal-induced increased susceptibility to chemoconvulsant-induced seizures in male rats. Since female rats recover from ethanol withdrawal (EW) more quickly than male rats across several behavioral measures, this study was designed to determine whether the effects of exercise on EW seizures also exhibited sex differences. Animals were maintained under no-wheel, locked-wheel or free-wheel conditions and ethanol was administered by liquid diet for 14 days with control animals pair-fed an isocaloric diet, after which seizure thresholds were determined at 1 day or 3 days of EW. Consistent with previous reports, females ran significantly more than males, regardless of diet condition. Introduction of the ethanol-containing liquid diet dramatically increased running for females during the day (rest) phase, with little impact on night phase activity. Consistent with previous reports, EW increased seizure susceptibility at 1 day in non-exercising males and females and at 3 days in males. These effects were attenuated by access to running wheels in both sexes. We also assessed the effects of sex, ethanol diet and exercise on ethanol clearance following an acute ethanol administration at 1 day EW in a separate set of animals. Blood ethanol concentrations at 30 min post-injection were lower in males, ethanol-exposed animals, and runners, but no interactions among these factors were detected. Interestingly, females displayed more rapid ethanol clearance than males and there were no effects of either diet or wheel access on clearance rates. Taken together, these data suggest that voluntary wheel running during ethanol administration provides protective effects against EW seizures in both males and females. This effect may be mediated, in part, in male, but not in female rat, by effects of exercise on early pharmacokinetic contributions. This supports the idea that encouraging alcoholics to exercise may benefit their recovery.

Sex differences in neuroadaptation to alcohol and withdrawal neurotoxicity

Recent work suggests that sex differences exist with regard to both the nature of neuroadaptation to alcohol during the development of dependence, and possibly, the neurodegenerative consequences of alcohol dependence. Volumetric studies in human samples show that females may demonstrate increased volumetric brain loss with equal or lesser dependence histories than males. Furthermore, animal studies demonstrate sex differences in glutamatergic, GABAergic, and adenosinergic receptor signaling and endocrine responses following prolonged alcohol exposure. These differences may influence the development of dependence, neuronal function, and viability, particularly during alcohol withdrawal. The present review discusses the current state of knowledge in this regard. It is concluded that there exists a clear need for a more extensive examination of potential sex differences in neurodegenerative consequences of alcohol dependence in men and women, particularly with regard to the role that alterations in amino acid signaling and hypothalamic-pituitary-adrenal axis function may play. Furthermore, we note the need for expanded examination of the unique role that alcohol withdrawal-associated neuronal activity may have in the development of dependence-associated neurotoxicity.

Lipids and addiction: how sex steroids, prostaglandins, and cannabinoids interact with drugs of abuse

Lipidomics aims to identify and characterize all endogenous species of lipids and understand their roles in cellular signaling and, ultimately, the functioning of the organism. We are on the cusp of fully understanding the functions of many of the lipid signaling systems that have been identified for decades (e.g., steroids, prostaglandins), whereas our understanding of newer lipid signaling systems (e.g., endocannabinoids, N-acyl amides) still lags considerably behind. With an emphasis on their roles in the neurophysiology of addiction, we will examine three classes of lipids--sex steroids, prostaglandins, and cannabinoids--and how they work synergistically in the neurocircuitry of motivation. We will first give a brief overview of the biosynthesis for each class of lipid and its receptors, and then summarize what is known about the collective roles of the lipids in cocaine and alcohol abuse. This approach provides a novel view of lipid signaling as a class of molecules and their synergistic roles in addiction.

Running wheel activity protects against increased seizure susceptibility in ethanol withdrawn male rats

Ethanol withdrawal is a dysphoric condition that arises from termination of ethanol intake by dependent individuals. Common withdrawal symptoms include anxiety, increased reactivity to stimuli and increased seizure susceptibility as well as the risk of increased seizure severity. We use an animal model of dependence and withdrawal to study withdrawal behaviors and potential underlying neurobiological mechanisms. For a number of years, we have quantified pentylenetetrazol seizure thresholds as an assessment of ethanol withdrawal at both one day and three days of withdrawal. Typically, we see a significant decrease in seizure threshold (increased sensitivity to seizure induction) that persists through three days of withdrawal for male rats. Increasing evidence indicates that voluntary exercise affords protection against various challenges to physical and psychological health, including ethanol-related challenges. Therefore, the current study investigated the effect of voluntary wheel running on seizure susceptibility following chronic ethanol administration and withdrawal. We found that voluntary wheel running attenuated the increased sensitivity to pentylenetetrazol-induced seizures observed with ethanol withdrawal, at both the one-day and three-day time points. This result was especially interesting as animals with access to the running wheels consumed more of the ethanol-containing diet. These findings showed that chronic voluntary wheel running reduces the severity of ethanol withdrawal in our animal model and suggest that exercise-based interventions may have some utility in the clinical management of heavy drinking and alcohol withdrawal.

Ethanol-induced loss-of-righting response during ethanol withdrawal in male and female rats: associations with alterations in Arc labeling

BACKGROUND

There is increasing evidence for relevant sex differences in responses to ethanol. Several investigations have found differences in expression and recovery from ethanol withdrawal (EW) in people and across various animal models. We have found that female rats recover more quickly than male rats and show differential responses to various behavioral assessments and pharmacological challenges during withdrawal. The purpose of this study was to determine whether sex differences in EW behaviors extend to the hypnotic effects of acute ethanol administration.

METHODS

We used a repeated measures design to assess duration and latency for loss-of-righting reflex following an acute injection of ethanol (4.2 g/kg; 20% w/v) to pair-fed control or ethanol-withdrawn animals at 1 and 3 days EW in male, female, and ovariectomized female (OVX) rats. We determined protein levels of the activity-regulated cytoskeletal protein (Arc), used as a marker for synaptic activity in glutamatergic synapses, in the motor cortex and prefrontal cortex across these same treatment conditions.

RESULTS

Ethanol-withdrawn animals had a reduced ethanol-induced sleep time compared to controls at 1 day EW. Sleep time remained shortened at 3 days EW for males and OVX, but not females. Arc protein levels in motor cortex and preoptic nuclei significantly increased at 1 day EW across all sex conditions, suggestive of an association with the reduced ethanol-induced sleep times during EW. Arc levels increased further for males and OVX, but not females, at the 3 days EW time point.

CONCLUSIONS

These findings add further support to sex differences in effects of and responses to ethanol. They suggest that the more rapid recovery from EW for females than males also includes expression of tolerance to the hypnotic effects of ethanol. These sex differences may involve some differential neuroadaptations in glutamatergic signaling.

Sex differences in the effects of ethanol pre-exposure during adolescence on ethanol-induced conditioned taste aversion in adult rats

Alcohol use, which typically begins during adolescence and differs between males and females, is influenced by both the rewarding and aversive properties of the drug. One way adolescent alcohol use may modulate later consumption is by reducing alcohol's aversive properties. Here, we used a conditioned taste aversion (CTA) paradigm to determine if pre-exposure to alcohol (ethanol) during adolescence would attenuate ethanol-induced CTA assessed in adulthood in a sex-dependent manner. Male and female Long-Evans rats were given intraperitoneal (i.p.) injections of saline or 3.0g/kg ethanol in a binge-like pattern during postnatal days (PD) 35-45. In adulthood (>PD 100), rats were given access to 0.1% saccharin, followed by saline or ethanol (1.0 or 1.5g/kg, i.p.), over four conditioning sessions. We found sex differences in ethanol-induced CTA, with males developing a more robust aversion earlier in conditioning. Sex differences in the effects of pre-exposure were also evident: males, but not females, showed an attenuated CTA in adulthood following ethanol pre-exposure, which occurred approximately nine weeks earlier. Taken together, these findings indicate that males are more sensitive to the aversive properties of ethanol than females. In addition, the ability of pre-exposure to the ethanol US to attenuate CTA is enhanced in males compared to females.

Elevated testosterone in females reveals a robust sex difference in altered androgen levels during chronic alcohol withdrawal

The endocrine disruption associated with alcohol (ethanol) abuse in both males and females is widely recognized. Ethanol intoxication and withdrawal in males results in significant reductions in androgen levels. Less is known about female alcoholics, and because the changes in testosterone concentrations remain controversial, we systematically characterized changes in sex steroids after chronic ethanol exposure and withdrawal in both sexes. Testosterone and 17β-estradiol concentrations were determined during chronic high intoxication, over a withdrawal time course, and following a period of abstinence using a genetic model of withdrawal vulnerability, the Withdrawal Seizure-Resistant (WSR) and -Prone (WSP) selected lines. In males, testosterone concentrations were significantly lower in intoxicated WSP mice after chronic ethanol exposure, and were dramatically and transiently reduced during the withdrawal period in both WSR and WSP lines. In contrast, testosterone levels were increased in intoxicated WSP females and in both WSR and WSP mice during withdrawal. Chronic ethanol exposure disrupted normal estrous cycling in WSP mice, associated with hyperandrogenemia while intoxicated. In abstinence, elevated testosterone was observed in both sexes but only in WSR mice. Estrogen levels were modestly reduced during withdrawal in both WSR and WSP lines, predominantly in males. These findings identify a mechanism based on altered androgen signaling that likely contributes to sex-specific responses during withdrawal. However, only WSR mice showed similar elevations in androgen long after withdrawal in both sexes, suggesting that genotype is an important determinant of steroid responses after abstinence. Increased androgen signaling in females as a consequence of chronic ethanol exposure may play an important and relatively uncharacterized role in sexually dimorphic responses to alcohol abuse.

Development of ethanol withdrawal-related sensitization and relapse drinking in mice selected for high- or low-ethanol preference

BACKGROUND

Previous studies have shown that high alcohol consumption is associated with low withdrawal susceptibility, while at the same time, other studies have shown that exposure to ethanol vapor increases alcohol drinking in rats and mice. In the present studies, we sought to shed light on this seeming contradiction using mice selectively bred for High- (HAP) and Low- (LAP) Alcohol Preference, first, assessing these lines for differences in signs of ethanol withdrawal and second, for differences in the efficacy of intermittent alcohol vapor exposure on elevating subsequent ethanol intake.

METHODS

Experiment 1 examined whether these lines of mice differed in ethanol withdrawal-induced CNS hyperexcitability and the development of sensitization to this effect following intermittent ethanol vapor exposure. Adult HAP and LAP lines (replicates 1 and 2), and the C3H/HeNcr inbred strain (included as a control genotype for comparison purposes) received intermittent exposure to ethanol vapor and were evaluated for ethanol withdrawal-induced seizures assessed by scoring handling-induced convulsions (HIC). Experiment 2 examined the influence of chronic intermittent ethanol exposure on voluntary ethanol drinking. Adult male and female HAP-2 and LAP-2 mice, along with male C57BL/6J (included as comparative controls) were trained to drink 10% ethanol using a limited access (2 h/d) 2-bottle choice paradigm. After stable baseline daily intake was established, mice received chronic intermittent ethanol vapor exposure in inhalation chambers. Ethanol intake sessions resumed 72 hours after final ethanol (or air) exposure for 5 consecutive days.

RESULTS

Following chronic ethanol treatment, LAP mice exhibited overall greater withdrawal seizure activity compared with HAP mice. In Experiment 2, chronic ethanol exposure/withdrawal resulted in a significant increase in ethanol intake in male C57BL/6J, and modestly elevated intake in HAP-2 male mice. Ethanol intake for male control mice did not change from baseline levels of intake. In contrast, HAP-2 female and LAP-2 mice of both sexes did not show changes in ethanol intake as a consequence of intermittent ethanol exposure.

CONCLUSIONS

Overall, these results indicate that the magnitude of ethanol withdrawal-related seizures is inversely related to inherited ethanol intake preference. Additionally, intermittent ethanol vapor exposure appears more likely to affect high-drinking mice (C57BL/6J and HAP-2) than low drinkers, although these animals are less affected by ethanol withdrawal.

Withdrawal severity after chronic intermittent ethanol in inbred mouse strains

BACKGROUND

To study withdrawal, ethanol is usually administered chronically without interruption. However, interest has recurred in models of episodic exposure. Increasing evidence suggests that chronic intermittent exposure to ethanol leads to a sensitization effect in both withdrawal severity and ethanol consumption. The goal of the present study was to examine mouse inbred strain differences in withdrawal severity following chronic intermittent exposure using the handling-induced convulsion as the behavioral endpoint. We also sought to compare the withdrawal responses of inbred strains across acute, chronic continuous, and chronic intermittent exposure regimens.

METHODS

Male mice from 15 standard inbred strains were exposed to ethanol vapor for 16 hours each day for 3 days and removed to an air chamber during the intervening 8 hours. Mice in the control groups were handled the same, except that they were exposed only to air. Daily blood ethanol concentrations were averaged for each mouse to estimate total dose of ethanol experienced.

RESULTS

Across strains, mice had an average daily blood ethanol concentration (BEC) of 1.45 +/- 0.02 mg/ml and we restricted the range of this value to 1.00-2.00 mg/ml. To evaluate strain differences, we divided data into two dose groups based on BEC, low dose (1.29 +/- 0.1 mg/ml) and high dose (1.71 +/- 0.02 mg/ml). After the third inhalation exposure, ethanol-exposed and air-exposed groups were tested hourly for handling-induced convulsions for 10 hour and at hour 24 and 25. Strains differed markedly in the severity of withdrawal (after subtraction of air control values) in both dose groups.

CONCLUSION

The chronic intermittent exposure paradigm is sufficient to elicit differential withdrawal responses across nearly all strains. Data from the high-dose groups correlated well with withdrawal data derived from prior acute (single high dose) and chronic continuous (for 72 hours) ethanol withdrawal studies, supporting the influence of common genes on all three responses.

Nicotine: alcohol reward interactions

It is well established that the continued intake of drugs of abuse is reinforcing-that is repeated consumption increases preference. This has been shown in some studies to extend to other drugs of abuse; use of one increases preference for another. In particular, the present review deals with the interaction of nicotine and alcohol as it has been shown that smoking is a risk factor for alcoholism and alcohol use is a risk factor to become a smoker. The review discusses changes in the brain caused by chronic nicotine and chronic alcohol intake to approach the possible mechanisms by which one drug increases the preference for another. Chronic nicotine administration was shown to affect nicotine receptors in the brain, affecting not only receptor levels and distribution, but also receptor subunit composition, thus affecting affinity to nicotine. Other receptor systems are also affected among others catecholamine, glutamate, GABA levels and opiate and cannabinoid receptors. In addition to receptor systems and transmitters, there are endocrine, metabolic and neuropeptide changes as well induced by nicotine. Similarly chronic alcohol intake results in changes in the brain, in multiple receptors, transmitters and peptides as discussed in this overview and also illustrated in the tables. The changes are sex and age-dependent-some changes in males are different from those in females and in general adolescents are more sensitive to drug effects than adults. Although nicotine and alcohol interact-not all the changes induced by the combined intake of both are additive-some are opposing. These opposing effects include those on locomotion, acetylcholine metabolism, nicotine binding, opiate peptides, glutamate transporters and endocannabinoid content among others. The two compounds lower the negative withdrawal symptoms of each other which may contribute to the increase in preference, but the mechanism by which preference increases-most likely consists of multiple components that are not clear at the present time. As the details of induced changes of nicotine and alcohol differ, it is likely that the mechanisms of increasing nicotine preference may not be identical to that of increasing alcohol preference. Stimulation of preference of yet other drugs may again be different -representing one aspect of drug specificity of reward mechanisms.

Manipulation of GABAergic steroids: Sex differences in the effects on alcohol drinking- and withdrawal-related behaviors

Alcoholism is a complex disorder that represents an important contributor to health problems worldwide and that is difficult to encompass with a single preclinical model. Additionally, alcohol (ethanol) influences the function of many neurotransmitter systems, with the interaction at gamma-aminobutyric acid(A) (GABA(A)) receptors being integral for ethanol's reinforcing and several withdrawal-related effects. Given that some steroid derivatives exert rapid membrane actions as potent positive modulators of GABA(A) receptors and exhibit a similar pharmacological profile to that of ethanol, studies in the laboratory manipulated GABAergic steroid levels and determined the impact on ethanol's rewarding- and withdrawal-related effects. Manipulations focused on the progesterone metabolite allopregnanolone (ALLO), since it is the most potent endogenous GABAergic steroid identified. The underlying hypothesis is that fluctuations in GABAergic steroid levels (and the resultant change in GABAergic inhibitory tone) alter sensitivity to ethanol, leading to changes in the positive motivational or withdrawal-related effects of ethanol. This review describes results that emphasize sex differences in the effects of ALLO and the manipulation of its biosynthesis on alcohol reward-versus withdrawal-related behaviors, with females being less sensitive to the modulatory effects of ALLO on ethanol-drinking behaviors but more sensitive to some steroid manipulations on withdrawal-related behaviors. These findings imply the existence of sex differences in the sensitivity of GABA(A) receptors to GABAergic steroids within circuits relevant to alcohol reward versus withdrawal. Thus, sex differences in the modulation of GABAergic neurosteroids may be an important consideration in understanding and developing therapeutic interventions in alcoholics.

Sex differences in acoustic startle responses and seizure thresholds between ethanol-withdrawn male and female rats

AIMS

We have found consistent and significant sex differences in recovery from the increased seizure susceptibility observed during ethanol withdrawal (EW) in our rat model system. The main objective of the present study was to determine if sex differences in EW generalized to an additional behavioral measure startle reactivity.

METHODS

Acoustic startle or seizure threshold responses were measured in separate groups of rats at 1 day or 3 days of EW.

RESULTS

Both pair-fed control and EW males showed greater increases in acoustic startle responses than either the female or ovariectomized female (OVX) counterparts. There was a selective effect of pregnanolone on acoustic startle in that it reduced peak force of response only at 3 days EW in male rats. Unexpectedly, it modestly increased startle reactivity in control female and OVX rats. Acute treatment with low-dose ethanol trended toward reducing startle responses in control animals, as expected, while generally enhancing startle responses during EW. All sex conditions showed an enhanced startle response during EW following administration of the higher dose of estradiol compared to control animals. Estradiol did not alter seizure thresholds in control animals. However, it was anticonvulsant for males at 3 days EW, females and OVX at 1 day EW.

CONCLUSIONS

Observed sex differences in the startle reactivity during EW were consistent with earlier findings comparing EW seizure risk in male and female rats. Responses of OVX suggested that both hormones and differences in brain structures between males and females have a role in these sex differences. Our findings add weight to recommendations that treatment of alcohol withdrawal in humans should consider hormonal status as well as withdrawal time.

Alcohol withdrawal seizures

The topic of alcohol withdrawal syndrome (AWS), including delirium tremens and especially seizures, is reviewed. From mice and rat studies, it is known that both N-methyl-d-aspartate (NMDA) and gamma-aminobutyric acid (GABA) receptors are involved in AWS. During alcohol intoxication chronic adaptations of NMDA and GABA receptors occur, and during alcohol withdrawal a hyperexcitable state develops. In studies on humans, during intoxication the NMDA receptors are activated and mediate tonic inhibition. In withdrawal, a rebound activation of these receptors occurs. Both GABA-A and GABA-B receptors, especially the alpha2 subunit of GABA-A receptors, are also likely involved. Homocysteine increases with active drinking, and in withdrawal, excitotoxicity likely is induced by a further increase in homocysteine, viewed as a risk factor for AWS and also as a screening tool. The dopamine transporter gene is also associated with AWS. Characteristics involves changes in the ECG, especially an increase in QT interval, and EEG changes, including abnormal quantified EEG, at times periodic lateralized epileptiform discharges, and especially seizures, usually occurring 6-48h after the cessation of drinking. Therapy has emphasized benzodiazepines, mainly diazepam and lorazepam, but more standard antiepileptic drugs, like carbamazepine and topiramate, are also effective and safe.

Alcohol-induced tolerance and physical dependence in mice with ethanol insensitive alpha1 GABA A receptors

BACKGROUND

Although many people consume alcohol (ethanol), it remains unknown why some become addicted. Elucidating the molecular mechanisms of tolerance and physical dependence (withdrawal) may provide insight into alcohol addiction. While the exact molecular mechanisms of ethanol action are unclear, gamma-aminobutyric acid type A receptors (GABA(A)-Rs) have been extensively implicated in ethanol action. The alpha1 GABA(A)-R subunit is associated with tolerance and physical dependence, but its exact role remains unknown. In this report, we tested the hypothesis that alpha1-GABA(A)-Rs mediate in part these effects of ethanol.

METHODS

Ethanol-induced behavioral responses related to tolerance and physical dependence were investigated in knockin (KI) mice that have ethanol-insensitive alpha1 GABA(A)-Rs and wildtype (WT) controls. Acute functional tolerance (AFT) was assessed using the stationary dowel and loss of righting reflex (LORR) assays. Chronic tolerance was assessed on the LORR, fixed speed rotarod, hypothermia, and radiant tail-flick assays following 10 consecutive days of ethanol exposure. Withdrawal-related hyperexcitability was assessed by handling-induced convulsions following 3 cycles of ethanol vapor exposure/withdrawal. Immunoblots were used to assess alpha1 protein levels.

RESULTS

Compared with controls, KI mice displayed decreased AFT and chronic tolerance to ethanol-induced motor ataxia, and also displayed heightened ethanol-withdrawal hyperexcitability. No differences between WT and KI mice were seen in other ethanol-induced behavioral measures. Following chronic exposure to ethanol, control mice displayed reductions in alpha1 protein levels, but KIs did not.

CONCLUSIONS

We conclude that alpha1-GABA(A)-Rs play a role in tolerance to ethanol-induced motor ataxia and withdrawal-related hyperexcitability. However, other aspects of behavioral tolerance and physical dependence do not rely on alpha1-containing GABA(A)-Rs.

Sex differences in the neurotoxic effects of adenosine A1 receptor antagonism during ethanol withdrawal: reversal with an A1 receptor agonist or an NMDA receptor antagonist

BACKGROUND

Neuronal adaptations that occur during chronic ethanol (EtOH) exposure have been observed to sensitize the brain to excitotoxic insult during withdrawal. The adenosine receptor system warrants further examination in this regard, as recent evidence has implicated adenosine receptor involvement in the behavioral effects of both EtOH exposure and withdrawal.

METHODS

The current studies examined effects of adenosine A(1) receptor manipulation on neuronal injury in EtOH-naive and EtOH-withdrawn male and female rat hippocampal slice cultures. EtOH-naive and EtOH pretreated (43.1 to 26.9 mM from days 5 to 15 DIV) cultures were exposed to the A(1) receptor agonist 2-Chloro-N(6)-cyclopentyladenosine (CCPA; 10 nM), the A(1) receptor antagonist 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX;10 nM), or the N-methyl-D-aspartate (NMDA) receptor antagonist D,L,-2-amino-5-phosphovalerate (APV; 20 microM) at 15 days in vitro (DIV). Cytotoxicity was measured in the primary neuronal layers of the dentate gyrus, CA3 and CA1 hippocampal regions by quantification of propidium iodide (PI) fluorescence after 24 hours. Immunohistochemical analysis of A(1) receptor abundance was conducted in EtOH-naive and EtOH pretreated slice cultures at 15 DIV.

RESULTS

Twenty-four hour exposure to DPCPX in EtOH-naive slice cultures did not produced neurotoxicity in any region of slice cultures. Though withdrawal from 10 day EtOH exposure produced no toxicity in either male or female slice cultures, exposure to DPCPX during 24 hours of EtOH withdrawal produced a marked increase in PI uptake in all hippocampal culture subregions in female cultures (to approximately 160% of control values). A significant effect for sex was observed in the CA1 region such that toxicity in females cultures exposed to the A(1) antagonist during withdrawal was greater than that observed in male cultures. These effects of DPCPX in EtOH withdrawn female and male slices were prevented by co-exposure to either the A(1) agonist CCPA or the NMDA receptor antagonist APV for 24 hours. No differences in the abundance of A(1) receptors were observed in male and female EtOH-naive or EtOH pretreated cultures.

CONCLUSIONS

The current findings suggest that the female hippocampus possesses an innate sensitivity to effects of EtOH exposure and withdrawal on neuronal excitability that is independent of hormonal influences. Further, this sex difference is not related to effects of EtOH exposure on A(1) receptor abundance, but likely reflects increased NMDA receptor-mediated signaling downstream of A(1) inhibition in females.

Decreased anticonvulsant efficacy of allopregnanolone during ethanol withdrawal in female Withdrawal Seizure-Prone vs. Withdrawal Seizure-Resistant mice

The GABAergic neurosteroid allopregnanolone (ALLO) has been repeatedly shown to have an increased anticonvulsant effect during ethanol withdrawal in rats and in C57BL/6J mice. In contrast, the seizure prone DBA/2J inbred strain and the Withdrawal Seizure-Prone (WSP) selected line exhibited decreased sensitivity to ALLO's anticonvulsant effect during ethanol withdrawal, with no change in sensitivity in the Withdrawal Seizure-Resistant (WSR) line. To date, only male mice have been tested. Thus, the present study examined ALLO sensitivity during ethanol withdrawal in female WSP and WSR mice, since females display less severe physical symptoms of withdrawal and have higher circulating ALLO levels than males. Female WSP and WSR mice were exposed to ethanol vapor or air for 72h. During peak ethanol withdrawal, separate groups of mice were injected with vehicle or ALLO (0, 3.2, 10, or 17mg/kg, i.p.) prior to the timed tail vein infusion of pentylenetetrazol (PTZ). ALLO injection significantly increased the threshold dose for onset to PTZ-induced convulsions, indicating an anticonvulsant effect, in female WSP and WSR mice. During ethanol withdrawal, sensitivity to ALLO's anticonvulsant effect was slightly increased in female WSR mice but was significantly decreased in female WSP mice. This line difference in sensitivity to ALLO during ethanol withdrawal in female mice was similar to that in the male mice. Notably, all seizure prone genotypes tested to date displayed tolerance to the anticonvulsant effect of ALLO during ethanol withdrawal, suggesting that decreased sensitivity of GABA(A) receptors to ALLO may contribute to the increased ethanol withdrawal phenotype.