The importance of glucocorticoids in alcohol dependence and neurotoxicity

Hormones, oxidized proteins, and lipids in alcoholism. Duration of remission

The instability of remission in alcohol dependence (AD) creates a need to search for criteria for predicting its duration. The aim of study was to determine the hormones, oxidized proteins, and lipids in patients with AD, and the possible relations between these parameters and the duration of remission. Blood samples were obtained from 49 male patients with AD after alcohol detoxification (Total group). Two groups of patients were formed: with unstable therapeutic remission up to 6 months (UTR-group); with stable therapeutic remission which lasted 12 months or longer (STR-group). The control group comprised men without AD. The levels of carbonylated proteins (CP), lipid peroxidation (TBA-RS) were determined in the blood plasma. The levels of cortisol, testosterone total, thyroid-stimulating hormone (TSH), triiodothyronine free (fT3), and thyroxine free (fT4) in the blood serum were measured. The Total group of patients showed an increase in CP, TBA-RS, Cortisol, cortisol/testosterone ratio, and a decrease in TSH, fT3, and fT3/fT4 levels. A set of parameters (T, fT3, fT4, cortisol/testosterone ratio) associated with unstable remission was identified.

The nonlinear association between HbA1c and cognitive impairment in patients with alcohol use disorder

Background: Extensive research has indicated that higher levels of glycated hemoglobin (HbA1c) are associated with poor cognitive performance regardless of the presence of diabetes. To our knowledge, the association between HbA1c levels and cognitive decline in patients with alcohol use disorder is not well understood. This study aimed to investigate whether HbA1c was associated with cognitive impairment in patients with alcohol use disorder. Methods: Patients admitted to the Psychiatry Department of the Third Hospital of Quzhou with a confirmed diagnosis of alcohol-related cognitive impairment were recruited between January 2019 and February 2022. Their HbA1c levels were measured, and they completed the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) after at least one week of monitored abstinence from alcohol. Univariate linear regression, multivariate linear regression and generalized additive models (GAMs) were used to investigate the association of HbA1c with MMSE and MoCA scores. Results: In total, 227 patients were included. Univariate and multivariate regression analyses suggested that HbA1c was negatively associated with MMSE and MoCA scores after adjustment for potential confounders (P < 0.05). The GAM analysis revealed that the relationships between the HbA1c level and the MMSE and MoCA scores were bell-shaped. The inflection points were 5.3% and 5.2% for the MMSE and MoCA respectively. Conclusion: The results of this study suggest that HbA1c levels are significantly related to cognitive impairment in patients with alcohol use disorder. Future studies are required to determine the effects of optimal glucose control in people with alcohol use disorder.

Cross-species epigenetic regulation of nucleus accumbens KCNN3 transcripts by excessive ethanol drinking

The underlying genetic and epigenetic mechanisms driving functional adaptations in neuronal excitability and excessive alcohol intake are poorly understood. Small-conductance Ca2+-activated K+ (KCa2 or SK) channels encoded by the KCNN family of genes have emerged from preclinical studies as a key contributor to alcohol-induced functional neuroadaptations in alcohol-drinking monkeys and alcohol-dependent mice. Here, this cross-species analysis focused on KCNN3 DNA methylation, gene expression, and single nucleotide polymorphisms, including alternative promoters in KCNN3, that could influence surface trafficking and function of KCa2 channels. Bisulfite sequencing analysis of the nucleus accumbens tissue from alcohol-drinking monkeys and alcohol-dependent mice revealed a differentially methylated region in exon 1A of KCNN3 that overlaps with a predicted promoter sequence. The hypermethylation of KCNN3 in the accumbens paralleled an increase in the expression of alternative transcripts that encode apamin-insensitive and dominant-negative KCa2 channel isoforms. A polymorphic repeat in macaque KCNN3 encoded by exon 1 did not correlate with alcohol drinking. At the protein level, KCa2.3 channel expression in the accumbens was significantly reduced in very heavy-drinking monkeys. Together, our cross-species findings on epigenetic dysregulation of KCNN3 represent a complex mechanism that utilizes alternative promoters to potentially impact the firing of accumbens neurons. Thus, these results provide support for hypermethylation of KCNN3 as a possible key molecular mechanism underlying harmful alcohol intake and alcohol use disorder.

Role of aldosterone and mineralocorticoid receptor (MR) in addiction: A scoping review

Preclinical and human studies suggest a role of aldosterone and mineralocorticoid receptor (MR) in addiction. This scoping review aimed to summarize (1) the relationship between alcohol and other substance use disorders (ASUDs) and dysfunctions of the aldosterone and MR, and (2) how pharmacological manipulations of MR may affect ASUD-related outcomes. Our search in four databases (MEDLINE, Embase, Web of Science, and Cochrane Library) indicated that most studies focused on the relationship between aldosterone, MR, and alcohol (n = 30), with the rest focused on opioids (n = 5), nicotine (n = 9), and other addictive substances (n = 9). Despite some inconsistencies, the overall results suggest peripheral and central dysregulations of aldosterone and MR in several species and that these dysregulations depended on the pattern of drug exposure and genetic factors. We conclude that MR antagonism may be a promising target in ASUD, yet future studies are warranted.

Cross-species epigenetic regulation of nucleus accumbens KCNN3 transcripts by excessive ethanol drinking

The underlying genetic and epigenetic mechanisms driving functional adaptations in neuronal excitability and excessive alcohol intake are poorly understood. Small-conductance Ca2+-activated K+ (KCa2 or SK) channels encoded by the KCNN family of genes have emerged from preclinical studies as a key contributor to alcohol-induced functional neuroadaptations in alcohol-drinking monkeys and alcohol dependent mice. Here, this cross-species analysis focused on KCNN3 DNA methylation, gene expression, and single nucleotide polymorphisms including alternative promoters in KCNN3 that could influence surface trafficking and function of KCa2 channels. Bisulfite sequencing analysis of the nucleus accumbens tissue from alcohol-drinking monkeys and alcohol dependent mice revealed a differentially methylated region in exon 1A of KCNN3 that overlaps with a predicted promoter sequence. The hypermethylation of KCNN3 in the accumbens paralleled an increase in expression of alternative transcripts that encode apamin-insensitive and dominant-negative KCa2 channel isoforms. A polymorphic repeat in macaque KCNN3 encoded by exon 1 did not correlate with alcohol drinking. At the protein level, KCa2.3 channel expression in the accumbens was significantly reduced in very heavy drinking monkeys. Together, our cross-species findings on epigenetic dysregulation of KCNN3 represent a complex mechanism that utilizes alternative promoters to impact firing of accumbens neurons. Thus, these results provide support for hypermethylation of KCNN3 as a possible key molecular mechanism underlying harmful alcohol intake and alcohol use disorder.

Alcohol-mediated susceptibility to lung fibrosis is associated with group 2 innate lymphoid cells in mice

Chronic alcohol ingestion promotes acute lung injury and impairs immune function. However, the mechanisms involved are incompletely understood. Here, we show that alcohol feeding enhances bleomycin-induced lung fibrosis and inflammation via the regulation of type 2 innate immune responses, especially by group 2 innate lymphoid cells (ILC2s). Neuroimmune interactions have emerged as critical modulators of lung inflammation. We found alcohol consumption induced the accumulation of ILC2 and reduced the production of the neuropeptide calcitonin gene-related peptide (CGRP), primarily released from sensory nerves and pulmonary neuroendocrine cells (PNECs). CGRP potently suppressed alcohol-driven type 2 cytokine signals in vivo. Vagal ganglia TRPV1+ afferents mediated immunosuppression occurs through the release of CGRP. Inactivation of the TRPV1 receptor enhanced bleomycin-induced fibrosis. In addition, mice lacking the CGRP receptor had the increased lung inflammation and fibrosis and type 2 cytokine production as well as exaggerated responses to alcohol feeding. Together, these data indicate that alcohol consumption regulates the interaction of CGRP and ILC2, which is a critical contributor of lung inflammation and fibrosis.

The Influence of the COVID-19 Pandemic Emergency on Alcohol Use: A Focus on a Cohort of Sicilian Workers

The period between the beginning and the end of the COVID-19 pandemic emergency generated a general state of stress, affecting both the mental state and physical well-being of the general population. Stress is the body's reaction to events or stimuli perceived as potentially harmful or distressing. Particularly when prolonged over time, it can promote the consumption of different psychotropic substances such as alcohol, and thus the genesis of various pathologies. Therefore, our research aimed to evaluate the differences in alcohol consumption in a cohort of 640 video workers who carried out activities in smart working, subjects particularly exposed to stressful situations due to the stringent rules of protection and prevention implemented during the pandemic. Furthermore, based on the results obtained from the administration of the AUDIT-C, we wanted to analyse the different modes of alcohol consumption (low, moderate, high, severe) to understand whether there is a difference in the amount of alcohol consumed that could predispose individuals to health problems. To this end, we administered the AUDIT-C questionnaire in two periods (T₀ and T₁), coinciding with annual occupational health specialist visits. The results of the present research showed an increase in the number of subjects consuming alcohol (p = 0.0005) and in their AUDIT-C scores (p < 0.0001) over the period considered. A significant decrease in subgroups who drink in a low-risk (p = 0.0049) mode and an increase in those with high (p = 0.00012) and severe risk (p = 0.0002) were also detected. In addition, comparing the male and female populations, it emerged that males have drinking patterns that lead to a higher (p = 0.0067) health risk of experiencing alcohol-related diseases than female drinking patterns. Although this study provides further evidence of the negative impact of the stress generated by the pandemic emergency on alcohol consumption, the influence of many other factors cannot be ruled out. Further research is needed to better understand the relationship between the pandemic and alcohol consumption, including the underlying factors and mechanisms driving changes in drinking behaviour, as well as potential interventions and support strategies to address alcohol-related harm during and after the pandemic.

Circadian rhythm shifts and alcohol access in adolescence synergistically increase alcohol preference and intake in adulthood in male C57BL/6 mice

BACKGROUND

Adolescents have a natural tendency to be night owls, maintaining delayed circadian rhythms, and this rhythm is in direct conflict with the early wake times required during the school year. This leads to 'social jetlag', chronic circadian stress or desynchrony (CD) in which the rhythm of the intrinsic body clock is out of sync with behavior. CD increases alcohol intake in adolescents and adults, yet it is unknown whether adolescent CD also increases long-term addiction risk. The goal of this study was to determine whether adolescent alcohol intake in CD would increase adult alcohol preference and intake in male C57BL/6 J mice.

METHODS

We measured free access alcohol intake, water intake, and wheel-running activity during a normal 12 h (h) baseline photoperiod and then during shifting lighting schedules (Experiment 1) or a shortened circadian day (Experiment 2).

RESULTS

In Experiment 1, altered lighting produced a persistent increase in adolescent alcohol intake and in binge-like drinking (drinking at least 5 licks per minute, with no more than a 1 min break in drinking) in adulthood, but only a transient increase in total alcohol intake for the first week after alcohol was reintroduced in adulthood. In Experiment 2, the circadian shift produced a significant increase in alcohol intake in both adolescence and adulthood. Molecular analysis demonstrated changes in plasma corticosterone and neuronal markers of stress and addiction at the conclusion of these experiments in the CD and alcohol-exposed groups.

CONCLUSIONS

Thus, we conclude that circadian stress during adolescence is sufficient to produce a long-lasting susceptibility to alcohol use.

Neurosteroids (allopregnanolone) and alcohol use disorder: From mechanisms to potential pharmacotherapy

Alcohol Use Disorder (AUD) is a multifaceted relapsing disorder that is commonly comorbid with psychiatric disorders, including anxiety. Alcohol exposure produces a plethora of effects on neurobiology. Currently, therapeutic strategies are limited, and only a few treatments - disulfiram, acamprosate, and naltrexone - are available. Given the complexity of this disorder, there is a great need for the identification of novel targets to develop new pharmacotherapy. The GABAergic system, the primary inhibitory system in the brain, is one of the well-known targets for alcohol and is responsible for the anxiolytic effects of alcohol. Interestingly, GABAergic neurotransmission is fine-tuned by neuroactive steroids that exert a regulatory role on several endocrine systems involved in neuropsychiatric disorders including AUD. Mounting evidence indicates that alcohol alters the biosynthesis of neurosteroids, whereas acute alcohol increases and chronic alcohol decreases allopregnanolone levels. Our recent work highlighted that chronic alcohol-induced changes in neurosteroid levels are mediated by epigenetic modifications, e.g., DNA methylation, affecting key enzymes involved in neurosteroid biosynthesis. These changes were associated with changes in GABAA receptor subunit expression, suggesting an imbalance between excitatory and inhibitory signaling in AUD. This review will recapitulate the role of neurosteroids in the regulation of the neuroendocrine system, highlight their role in the observed allostatic load in AUD, and develop a framework from mechanisms to potential pharmacotherapy.

HPA-Axis Activity and Nutritional Status Correlation in Individuals with Alcohol Use Disorder

Impaired activity of the hypothalamic-pituitary-adrenal axis (HPA-axis) is evident in alcohol use disorder (AUD), and may be implicated in various nutritional and metabolic alterations often seen in individuals with this disorder. The present study examined a possible correlation between HPA-axis activity and nutritional status components in individuals with AUD. Fourteen AUD and fourteen non-AUD males participated; anthropometric and body composition measurements were made, and fasting blood samples were analysed for plasma adrenal corticotropic hormone (ACTH), catecholamines, cortisol and beta-endorphin. Nutrient intake was estimated via a three-day diet record. Waist circumference and waist-to-hip ratio were increased in the AUD group. Thiamine and folic intake were lower in AUD group, although only folic acid intake was insufficient in both AUD and non-AUD groups. Increased epinephrine and norepinephrine were also observed in AUD group compared to non-AUD group. No clear correlation between HPA-axis activity and nutritional status components was found. This study showed that nutrient intake, body composition, and HPA-axis activity were different among AUD and non-AUD individuals. More research on the correlation between nutritional status and HPA-axis activity in AUD individuals should be conducted.

Induction of the hepatic aryl hydrocarbon receptor by alcohol dysregulates autophagy and phospholipid metabolism via PPP2R2D

Disturbed lipid metabolism precedes alcoholic liver injury. Whether and how AhR alters degradation of lipids, particularly phospho-/sphingo-lipids during alcohol exposure, was not explored. Here, we show that alcohol consumption in mice results in induction and activation of aryl hydrocarbon receptor (AhR) in the liver, and changes the hepatic phospho-/sphingo-lipids content. The levels of kynurenine, an endogenous AhR ligand, are elevated with increased hepatic tryptophan metabolic enzymes in alcohol-fed mice. Either alcohol or kynurenine treatment promotes AhR activation with autophagy dysregulation via AMPK. Protein Phosphatase 2 Regulatory Subunit-Bdelta (Ppp2r2d) is identified as a transcriptional target of AhR. Consequently, PPP2R2D-dependent AMPKα dephosphorylation causes autophagy inhibition and mitochondrial dysfunction. Hepatocyte-specific AhR ablation attenuates steatosis, which is associated with recovery of phospho-/sphingo-lipids content. Changes of AhR targets are corroborated using patient specimens. Overall, AhR induction by alcohol inhibits autophagy in hepatocytes through AMPKα, which is mediated by Ppp2r2d gene transactivation, revealing an AhR-dependent metabolism of phospho-/sphingo-lipids.

Enteric VIP-producing neurons maintain gut microbiota homeostasis through regulating epithelium fucosylation

Interactions between the enteric nervous system (ENS) and intestinal epithelium are thought to play a vital role in intestinal homeostasis. How the ENS monitors the frontier with commensal and pathogenic microbes while maintaining epithelial function remains unclear. Here, by combining subdiaphragmatic vagotomy with transcriptomics, chemogenetic strategy, and coculture of enteric neuron-intestinal organoid, we show that enteric neurons expressing VIP shape the α1,2-fucosylation of intestinal epithelial cells (IECs). Mechanistically, neuropeptide VIP activates fut2 expression via the Erk1/2-c-Fos pathway through the VIPR1 receptor on IECs. We further demonstrate that perturbation of enteric neurons leads to gut dysbiosis through α1,2-fucosylation in the steady state and results in increased susceptibility to alcohol-associated liver disease (ALD). This was attributed to an imbalance between beneficial Bifidobacterium and opportunistic pathogenic Enterococcus faecalis in ALD. In addition, Bifidobacterium α1,2-fucosidase may promote Bifidobacterium adhesion to the mucosal surface, which restricts Enterococcus faecalis overgrowth and prevents ALD progression.

The Combined Effects of Perinatal Ethanol and Early-Life Stress on Cognition and Risk-Taking Behavior through Oxidative Stress in Rats

Both prenatal ethanol and early-life stress have been shown to induce reduced risk-taking and explorative behavior as well as cognitive dysfunction in the offspring. In this study, we examined the effect of combined exposure to ethanol and early stress on maternal care, exploratory behavior, memory performances, and oxidative stress in male offspring. Pregnant rats were exposed to ethanol (4 g/kg) from gestational day (GD) 6-to postnatal day (PND) 14 and limited nesting material (LNS) from PND0-PND14 individually or in combination. Maternal behavior was evaluated during diurnal cycle. The level of corticosterone hormone and markers of oxidative stress were evaluated in the pups. Risk-taking and explorative behavior were assessed with the elevated-plus maze (EPM) test and cognitive behavior with the Morris water maze (MWM), novel object recognition (NORT), and object location memory (OLM) tests. In the mothers, perinatal alcohol or LNS either alone or in combination decreased maternal behavior. In the offspring, the combination of the two factors significantly increased the pup's plasma corticosterone concentration in comparison with ethanol and LNS alone. Reduced risk-taking behavior was observed in the ethanol, LNS and ethanol + LNS groups compared with the control group, and this was amplified in the co-exposure of ethanol and LNS groups. The MWM, NORT, and OLM tests revealed spatial and recognition memory impairment in the ethanol and LNS groups. This impairment was more profound in the co-exposure of ethanol and LNS. Also, we observed a significant decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and an increase in malondialdehyde (MDA) level in the hippocampus of ethanol and LNS co-exposed animals as compared with individual exposure of ethanol and LNS. While each factor independently produced similar outcomes, the results indicate that the dual exposure paradigm could significantly strengthen the outcomes.

Long-term consequences of alcohol use in early adolescent mice: Focus on neuroadaptations in GR, CRF and BDNF

Our aim was to assess the cognitive and emotional state, as well as related-changes in the glucocorticoid receptor (GR), the corticotropin-releasing factor (CRF) and the brain-derived neurotrophic factor (BDNF) expression of adolescent C57BL/6J male mice after a 5-week two-bottle choice protocol (postnatal day [pd]21 to pd52). Additionally, we wanted to analyse whether the behavioural and neurobiological effects observed in late adolescence (pd62) lasted until adulthood (pd84). Behavioural testing revealed that alcohol during early adolescence increased anxiety-like and compulsive-related behaviours, which was maintained in adulthood. Concerning cognition, working memory was only altered in late adolescent mice, whereas object location test performance was impaired in both ages. In contrast, novel object recognition remained unaltered. Immunohistochemical analysis showed that alcohol during adolescence diminished BDNF+ cells in the cingulate cortex, the hippocampal CA1 layer and the central amygdala. Regarding hypothalamic-pituitary-adrenal axis (HPA) functioning, alcohol abuse increased the GR and CRF expression in the hypothalamic paraventricular nucleus and the central amygdala. Besides this, GR density was also higher in the prelimbic cortex and the basolateral amygdala, regardless of the animals' age. Our findings suggest that adolescent alcohol exposure led to long-term behavioural alterations, along with changes in BDNF, GR and CRF expression in limbic brain areas involved in stress response, emotional regulation and cognition.

Central role of intestinal epithelial glucocorticoid receptor in alcohol- and corticosterone-induced gut permeability and systemic response

Corticosterone, the stress hormone, exacerbates alcohol-associated tissue injury, but the mechanism involved is unknown. We examined the role of the glucocorticoid receptor (GR) in corticosterone-mediated potentiation of alcohol-induced gut barrier dysfunction and systemic response. Hepatocyte-specific GR-deficient (GR^ΔHC ) and intestinal epithelial-specific GR-deficient (GR^ΔIEC ) mice were fed ethanol, combined with corticosterone treatment. Intestinal epithelial tight junction integrity, mucosal barrier function, microbiota dysbiosis, endotoxemia, systemic inflammation, liver damage, and neuroinflammation were assessed. Corticosterone potentiated ethanol-induced epithelial tight junction disruption, mucosal permeability, and inflammatory response in GR^ΔHC mouse colon; these effects of ethanol and corticosterone were absent in GR^ΔIEC mice. Gut microbiota compositions in ethanol-fed GR^ΔHC and GR^ΔIEC mice were similar to each other. However, corticosterone treatment in ethanol-fed mice shifted the microbiota composition to distinctly different directions in GR^ΔHC and GR^ΔIEC mice. Ethanol and corticosterone synergistically elevated the abundance of Enterobacteriaceae and Escherichia coli and reduced the abundance of Lactobacillus in GR^ΔHC mice but not in GR^ΔIEC mice. In GR^ΔHC mice, corticosterone potentiated ethanol-induced endotoxemia and systemic inflammation, but these effects were absent in GR^ΔIEC mice. Interestingly, ethanol-induced liver damage and its potentiation by corticosterone were observed in GR^ΔHC mice but not in GR^ΔIEC mice. GR^ΔIEC mice were also resistant to ethanol- and corticosterone-induced inflammatory response in the hypothalamus. These data indicate that the intestinal epithelial GR plays a central role in alcohol- and corticosterone-induced gut barrier dysfunction, microbiota dysbiosis, endotoxemia, systemic inflammation, liver damage, and neuroinflammation. This study identifies a novel target for potential therapeutic for alcohol-associated tissue injury.

Carbenoxolon Is Capable to Regulate the Mitochondrial Permeability Transition Pore Opening in Chronic Alcohol Intoxication

Background: carbenoxolone, which is a derivative of glyceretic acid, is actively used in pharmacology for the treatment of diseases of various etiologies. In addition, we have shown carbenoxolone as an effective inducer of mitochondrial permeability transition pore in rat brain and liver mitochondria. Methods: in the course of this work, comparative studies were carried out on the effect of carbenoxolone on the parameters of mPTP functioning in mitochondria isolated from the liver of control and alcoholic rats. Results: within the framework of this work, it was found that carbenoxolone significantly increased its effect in the liver mitochondria of rats with chronic intoxication. In particular, this was expressed in a reduction in the lag phase, a decrease in the threshold calcium concentration required to open a pore, an acceleration of high-amplitude cyclosporin-sensitive swelling of mitochondria, as well as an increase in the effect of carbenoxolone on the level of mitochondrial membrane-bound proteins. Thus, as a result of the studies carried out, it was shown that carbenoxolone is involved in the development/modulation of alcohol tolerance and dependence in rats.

An in vivo explorative study to observe the protective effects of Puerariae flos extract on chronic ethanol exposure and withdrawal male mice

Protective effects of Puerariae flos extract (PFE) on ethanol (EtOH) exposure have been previously verified. This study attempts to explore the protective effects of PEF on EtOH withdrawal models. Sixty male Kunming mice were involved which were randomly divided into five groups (intact control, EtOH group (35-day EtOH exposure), EtOH withdrawal group (28-day exposure + 7-day withdrawal), EtOH withdrawal group + positive control (Deanxit) group, and EtOH withdrawal group + PFE group). The changes of neuropsychological behaviors; hippocampal BDNF expression and CA1 neuronal density; and plasma corticotropin-releasing hormone (CRH), ACTH, and CORT levels were observed. It was found that depression-like behaviors reduced by EtOH exposure and increased by withdrawal under the 28-day EtOH exposure and 7-day withdrawal conditions. In addition, anxiety-like behaviors worsened by EtOH exposure and unchanged by withdrawal. Deanxit and PEF ameliorated such behaviors (vs. withdrawal group). Hippocampal BDNF expression was significantly downregulated by EtOH exposure and upregulated by withdrawal. Deanxit and PEF significantly upregulated the BDNF expression. The hippocampal CA1 neuronal density significantly decreased by EtOH exposure but unchanged by withdrawal and treatments. The plasma CRH, ACTH, and CORT levels show a significant enhancement by EtOH exposure and reduced by withdrawal. They were further reduced by Deanxit and PEF. The protective effects of PEF on EtOH chronic withdrawal mouse models were verified. The results of this study also indicated a complicated scenario of neuropsychological behaviors, hippocampal BDNF expression, and hypothalamic-pituitary-adrenal axis which are affected by the timing of EtOH exposure and withdrawal.

Effects of cortisol administration on craving during in vivo exposure in patients with alcohol use disorder

Alcohol-associated memories and craving play a crucial role in the development and maintenance of alcohol use disorder (AUD). As treatment options are limited in AUD, novel treatment strategies focus on the manipulation of alcohol-associated memories. The stress hormone cortisol affects various memory processes, and first clinical studies have shown that it inhibits the retrieval of disorder-specific memories and enhances extinction memory. This study aimed to investigate the effects of a single oral administration of cortisol on craving in patients with AUD during repeated in vivo exposure to alcohol pictures and the preferred alcoholic drink. In a double-blind, block-randomized, placebo-controlled cross-over design, 46 patients with AUD were treated with two sessions of in vivo exposure to alcohol. Cortisol (20 mg) or placebo was orally administered 1 h before each test day. Craving, stress, and cortisol were repeatedly measured during exposure sessions. Results show, that cortisol administration had distinct effects on craving depending on the severity of AUD and test day. While cortisol administration significantly enhanced craving during exposure on the first test day in patients with less severe AUD, it reduced craving in patients with more severe AUD. Independent of the cortisol administration, repeated in vivo exposure reduced craving from test day 1 to test day 2. In conclusion, adding cortisol to in vivo exposure might be a promising approach for reducing the strength of alcohol-associated memories and might promote the consolidation of extinction memory in patients with severe AUD. However, the differential effect of cortisol on craving depending on AUD severity cannot be conclusively explained and highlights the need for future studies elucidating the underlying mechanism.

Genome-wide methylation in alcohol use disorder subjects: implications for an epigenetic regulation of the cortico-limbic glucocorticoid receptors (NR3C1)

Environmental factors, including substance abuse and stress, cause long-lasting changes in the regulation of gene expression in the brain via epigenetic mechanisms, such as DNA methylation. We examined genome-wide DNA methylation patterns in the prefrontal cortex (PFC, BA10) of 25 pairs of control and individuals with alcohol use disorder (AUD), using the Infinium^® MethylationEPIC BeadChip. We identified 5254 differentially methylated CpGs (p_nominal < 0.005). Bioinformatic analyses highlighted biological processes containing genes related to stress adaptation, including the glucocorticoid receptor (encoded by NR3C1). Considering that alcohol is a stressor, we focused our attention on differentially methylated regions of the NR3C1 gene and validated the differential methylation of several genes in the NR3C1 network. Chronic alcohol drinking results in a significant increased methylation of the NR3C1 exon variant 1_H, with a particular increase in the levels of 5-hydroxymethylcytosine over 5-methylcytosine. These changes in DNA methylation were associated with reduced NR3C1 mRNA and protein expression levels in PFC, as well as other cortico-limbic regions of AUD subjects when compared with controls. Furthermore, we show that the expression of several stress-responsive genes (e.g., CRF, POMC, and FKBP5) is altered in the PFC of AUD subjects. These stress-response genes were also changed in the hippocampus, a region that is highly susceptible to stress. These data suggest that alcohol-dependent aberrant DNA methylation of NR3C1 and consequent changes in other stress-related genes might be fundamental in the pathophysiology of AUD and lay the groundwork for treatments targeting the epigenetic mechanisms regulating NR3C1 in AUD.

Features of neurosteroid support of the state of alcohol dependence and its correction with dosed physical load in rats

The role of steroid hormones in regulation of the functions of the emotiogenic limbic-neocortical system has been actively studied over the recent decades in order to determine their synthesis in the brain structures and role in the development and maintenance of dependence on psychoactive substances. However, the wide range of neurosteroids and their metabolites, as well as structural specific features of the synthesis of both neurohormones and their receptors make it difficult to obtain experimental data and interpret the results of the study. The participation of progesterone, cortisol, testosterone and estradiol in the development of alcohol dependence and the changes in their concentrations in the hypothalamus, hippocampus, amygdala and serum under the influence of dosed physical load were studied in 48 outbred adult male rats. Alcohol dependence was modeled by means of consuming food containing alcohol in the dose of 1.25 g of ethanol per 1 kg of rat body weight for two months. Dosed physical load was reproduced by a rat running in a wheel for 30 minutes daily for 7–10 days against the background of alcohol withdrawal. Neuroethological testing of craving for alcohol, EEG recording of the neocortex, hippocampus and amygdala was performed using a computer-diagnostic complex. The concentration of steroid hormones was determined in the structures of the brain and blood serum by the enzyme-linked immunosorbent assay. It was shown that dosed physical load attenuated the alcohol motivation of rats. On the 5th day it suppressed the electrographic manifestations of paroxysmal activity in the hippocampus and increased the level of the theta-rhythm in the amygdala, and on the 7th day it activated the neocortex with increasing beta-rhythm. This effect was accompanied by an increase in serum testosterone level against the background of maintaining functional tension of the peripheral glucocorticoid link of the hypothalamus-pituitary-adrenal system, which was observed in a state of alcohol dependence. The study demonstrated that progesterone plays the key role in allostatic rearrangements of the functional state of animals. An imbalance of progesterone levels was revealed in the brain structures: an increase – in the hypothalamus and hippocampus, and a decrease – in the amygdala under alcohol dependence; a decrease – in the hippocampus with recovery in the amygdala against the background of its high level in the hypothalamus, which occurs under the influence of dosed physical load on the rats under alcohol withdrawal. Thus, the dosed physical load is a promising approach to alcohol dependence rehabilitation.

Epigenetic landscape of stress surfeit disorders: Key role for DNA methylation dynamics

Chronic exposure to stress throughout lifespan alters brain structure and function, inducing a maladaptive response to environmental stimuli, that can contribute to the development of a pathological phenotype. Studies have shown that hypothalamic-pituitary-adrenal (HPA) axis dysfunction is associated with various neuropsychiatric disorders, including major depressive, alcohol use and post-traumatic stress disorders. Downstream actors of the HPA axis, glucocorticoids are critical mediators of the stress response and exert their function through specific receptors, i.e., the glucocorticoid receptor (GR), highly expressed in stress/reward-integrative pathways. GRs are ligand-activated transcription factors that recruit epigenetic actors to regulate gene expression via DNA methylation, altering chromatin structure and thus shaping the response to stress. The dynamic interplay between stress response and epigenetic modifiers suggest DNA methylation plays a key role in the development of stress surfeit disorders.

Double-blind, placebo-controlled trial of mifepristone on cognition and depression in alcohol dependence

Background

Alcohol dependence is a significant issue contributing to disease burden. Changes in cortisol concentrations during alcohol withdrawal are associated with cognitive deficits and symptoms of depression. Current treatments are only successful for a small proportion of people and do not target cognitive deficits and symptoms of depression experienced by those who are alcohol dependent. The aim of this research is to determine the potential efficacy of mifepristone, a type II glucocorticoid receptor antagonist, to prevent symptoms of depression and cognitive deficits following alcohol detoxification.

Methods

This was a phase 2 therapeutic use trial. It was a double-blind randomised controlled clinical trial of mifepristone versus inactive placebo treatment. The trial aimed to recruit 120 participants who met the inclusion criteria: (1) male, (2) aged 18–60 years inclusive, and (3) alcohol dependent for 5 or more years. Participants were randomised to 600 mg a day mifepristone (200 mg morning, afternoon, and evening) for 7 days and 400 mg for the subsequent 7 days (200 mg morning and evening) or the equivalent number of placebo tablets for 14 days. Primary outcome measures were cognitive function (measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB)) and symptoms of depression (measured using the Beck Depression Inventory (BDI)) at 4 weeks post-randomisation.

Results

Difficulties recruiting participants due to significant changes in the provision of inpatient care for alcohol dependence resulted in only 27 participants recruited to the trial, with data available for 21 participants. Fourteen participants were randomised to receive mifepristone and 13 to receive placebo.

Conclusion

Larger trials would be needed to draw conclusions about the efficacy of mifepristone.

Trial registration

ISRCTN registry ISRCTN54001953. Registered on 29 September 2011.

Transcriptional mechanisms of drug addiction

Drugs of abuse can modify gene expression in brain reward and motivation centers, which contribute to the structural and functional remodeling of these circuits that impacts the emergence of a state of addiction. Our understanding of how addictive drugs induce transcriptomic plasticity in addiction-relevant brain regions, particularly in the striatum, has increased dramatically in recent years. Intracellular signaling machineries, transcription factors, chromatin modifications, and regulatory noncoding RNAs have all been implicated in the mechanisms through which addictive drugs act in the brain. Here, we briefly summarize some of the molecular mechanisms through which drugs of abuse can exert their transcriptional effects in the brain region, with an emphasis on the role for microRNAs in this process.


Organ-differential responses to ethanol and kynurenic acid, a component of alcoholic beverages in gene transcription

Excessive alcohol (ethanol) use has long been known to affect human health negatively. However, the underlying molecular basis is incompletely understood. Moreover, consumption of alcohol is often mixed with kynurenic acid (KYNA), an abundant tryptophan metabolite produced during fermentation. The combined effect of ethanol and KYNA on host gene expression has not been investigated. The current study used mice as the model to interrogate the impact of ethanol and/or KYNA on global gene transcription. Adult male mice were administered with 2 g/kg ethanol and/or 0.1 mg/kg KYNA by gavage once a day for a week. Three organs: brain, kidney, and liver were collected and their total RNAs extracted for transcriptome sequencing and quantitative real-time PCR. Gene ontology, Kyoto encyclopedia of genes, and genomes pathway analyses revealed that alcohol affects the three organs differentially. Furthermore, the gene expression profile from alcohol and KYNA co-administration was significantly different from that of alcohol or KYNA administration alone. Strikingly, Indolamine 2,3-dioxygenase 1, a rate-limiting enzyme in tryptophan metabolism, was significantly increased in the brain after a combined exposure of alcohol and KYNA, suggesting that Trp metabolism was skewed towards the kynurenine pathway in the brain. Our systemic analysis provides new insights into the mechanism whereby alcohol and KYNA affects organ functions.

Enkephalins and ACTH in the mammalian nervous system

The pentapeptides methionine-enkephalin and leucine-enkephalin belong to the opioid family of peptides, and the non-opiate peptide adrenocorticotropin hormone (ACTH) to the melanocortin peptide family. Enkephalins/ACTH are derived from pro-enkephalin, pro-dynorphin or pro-opiomelanocortin precursors and, via opioid and melanocortin receptors, are responsible for many biological activities. Enkephalins exhibit the highest affinity for the δ receptor, followed by the μ and κ receptors, whereas ACTH binds to the five subtypes of melanocortin receptor, and is the only member of the melanocortin family of peptides that binds to the melanocortin-receptor 2 (ACTH receptor). Enkephalins/ACTH and their receptors exhibit a widespread anatomical distribution. Enkephalins are involved in analgesia, angiogenesis, blood pressure, embryonic development, emotional behavior, feeding, hypoxia, limbic system modulation, neuroprotection, peristalsis, and wound repair; as well as in hepatoprotective, motor, neuroendocrine and respiratory mechanisms. ACTH plays a role in acetylcholine release, aggressive behavior, blood pressure, bone maintenance, hyperalgesia, feeding, fever, grooming, learning, lipolysis, memory, nerve injury repair, neuroprotection, sexual behavior, sleep, social behavior, tissue growth and stimulates the synthesis and secretion of glucocorticoids. Enkephalins/ACTH are also involved in many pathologies. Enkephalins are implicated in alcoholism, cancer, colitis, depression, heart failure, Huntington's disease, influenza A virus infection, ischemia, multiple sclerosis, and stress. ACTH plays a role in Addison's disease, alcoholism, cancer, Cushing's disease, dermatitis, encephalitis, epilepsy, Graves' disease, Guillain-Barré syndrome, multiple sclerosis, podocytopathies, and stress. In this review, we provide an updated description of the enkephalinergic and ACTH systems.

Targeting the Glucocorticoid Receptors During Alcohol Withdrawal to Reduce Protracted Neurocognitive Disorders

Persistent regional glucocorticoid (GC) dysregulation in alcohol-withdrawn subjects emerges as a key factor responsible for protracted molecular and neural alterations associated with long-term cognitive dysfunction. Regional brain concentrations of corticosterone vary independently from plasma concentrations in alcohol-withdrawn subjects, which may account for the treatment of alcohol withdrawal-induced persistent pathology. Thus, from a pharmacological point of view, a main issue remains to determine the relative efficacy of compounds targeting the GC receptors to attenuate or suppress the long-lasting persistence of brain regional GC dysfunctions in abstinent alcoholics, as well as persistent changes of neural plasticity. Data from animal research show that acting directly on GC receptors during the withdrawal period, via selective antagonists, can significantly counteract the development and persistence of cognitive and neural plasticity disorders during protracted abstinence. A critical remaining issue is to better assess the relative long-term efficacy of GC antagonists and other compounds targeting the corticotropic axis activity such as gamma-aminobutyric acid A (GABA_A) and GABA_B agonists. Indeed, benzodiazepines (acting indirectly on GABA_A receptors) and baclofen (agonist of the GABA_B receptor) are the compounds most widely used to reduce alcohol dependence. Clinical and preclinical data suggest that baclofen exerts an effective and more powerful counteracting action on such persistent cognitive and endocrine dysfunctions as compared to diazepam, even though its potential negative effects on memory processes, particularly at high doses, should be better taken into account.

Hsp90 Heterocomplexes Regulate Steroid Hormone Receptors: From Stress Response to Psychiatric Disease

The hypothalamus-pituitary-adrenal (HPA) axis directly controls the stress response. Dysregulation of this neuroendocrine system is a common feature among psychiatric disorders. Steroid hormone receptors, like glucocorticoid receptor (GR), function as transcription factors of a diverse set of genes upon activation. This activity is regulated by molecular chaperone heterocomplexes. Much is known about the structure and function of these GR/heterocomplexes. There is strong evidence suggesting altered regulation of steroid receptor hormones by chaperones, particularly the 51 kDa FK506-binding protein (FKBP51), may work with environmental factors to increase susceptibility to various psychiatric illnesses including post-traumatic stress disorder (PTSD), major depressive disorder (MDD), and anxiety. This review highlights the regulation of steroid receptor dynamics by the 90kDa heat shock protein (Hsp90)/cochaperone heterocomplexes with an in depth look at how the structural regulation and imbalances in cochaperones can cause functional effects on GR activity. Links between the stress response and circadian systems and the development of novel chaperone-targeting therapeutics are also discussed.

In Memoriam: Sidney George Shaw, DPhil (1948-2017)

On March 4, 2017 at the age of 68, Sidney George Shaw (Sid) unexpectedly died from complications following surgery, only four years after retiring from the University of Bern. Trained in biochemistry at Oxford University, Sid had quickly moved into molecular pharmacology and became a key investigator in the field of enzyme biochemistry, vasoactive peptide research, and receptor signaling. Sid spent half his life in Switzerland, after moving to the University of Bern in 1984. This article, written by his friends and colleagues who knew him and worked with him during different stages of his career, summarizes his life, his passions, and his achievements in biomedical research. It also includes personal memories relating to a dear friend and outstanding scientist whose intellectual curiosity, humility, and honesty will remain an example to us all.

Advancing Pharmacotherapy Development from Preclinical Animal Studies

Animal models provide rapid, inexpensive assessments of an investigational drug's therapeutic potential. Ideally, they support the plausibility of therapeutic efficacy and provide a rationale for further investigation. Here, I discuss how the absence of clear effective-ineffective categories for alcohol use disorder (AUD) medications and biases in the clinical and preclinical literature affect the development of predictive preclinical alcohol dependence (AD) models. Invoking the analogical argument concept from the philosophy of science field, I discuss how models of excessive alcohol drinking support the plausibility of clinical pharmacotherapy effects. Even though these models are not likely be completely discriminative, they are sensitive to clinically effective medications and have revealed dozens of novel medication targets. In that context, I discuss recent preclinical work on GLP-1 receptor agonists, phosphodiesterase inhibitors, glucocorticoid receptor antagonists, nociception agonists and antagonists, and CRF1 antagonists. Clinically approved medications are available for each of these drug classes. I conclude by advocating a translational approach in which drugs are evaluated highly congruent preclinical models and human laboratory studies. Once translation is established, I suggest the burden is to develop hypothesis-based therapeutic interventions maximizing the impact of the confirmed pharmacotherapeutic effects in the context of additional variables falling outside the model.

Influence of stress associated with chronic alcohol exposure on drinking

Stress is commonly regarded as an important trigger for relapse and a significant factor that promotes increased motivation to drink in some individuals. However, the relationship between stress and alcohol is complex, likely changing in form during the transition from early moderated alcohol use to more heavy uncontrolled alcohol intake. A growing body of evidence indicates that prolonged excessive alcohol consumption serves as a potent stressor, producing persistent dysregulation of brain reward and stress systems beyond normal homeostatic limits. This progressive dysfunctional (allostatic) state is characterized by changes in neuroendocrine and brain stress pathways that underlie expression of withdrawal symptoms that reflect a negative affective state (dysphoria, anxiety), as well as increased motivation to self-administer alcohol. This review highlights literature supportive of this theoretical framework for alcohol addiction. In particular, evidence for stress-related neural, physiological, and behavioral changes associated with chronic alcohol exposure and withdrawal experience is presented. Additionally, this review focuses on the effects of chronic alcohol-induced changes in several pro-stress neuropeptides (corticotropin-releasing factor, dynorphin) and anti-stress neuropeptide systems (nocicepton, neuropeptide Y, oxytocin) in contributing to the stress, negative emotional, and motivational consequences of chronic alcohol exposure. Studies involving use of animal models have significantly increased our understanding of the dynamic stress-related physiological mechanisms and psychological underpinnings of alcohol addiction. This, in turn, is crucial for developing new and more effective therapeutics for treating excessive, harmful drinking, particularly stress-enhanced alcohol consumption. This article is part of the Special Issue entitled "Alcoholism".

Analyses of differentially expressed genes after exposure to acute stress, acute ethanol, or a combination of both in mice

Alcohol abuse is a complex disorder, which is confounded by other factors, including stress. In the present study, we examined gene expression in the hippocampus of BXD recombinant inbred mice after exposure to ethanol (NOE), stress (RSS), and the combination of both (RSE). Mice were given an intraperitoneal (i.p.) injection of 1.8 g/kg ethanol or saline, and subsets of both groups were exposed to acute restraint stress for 15 min or controls. Gene expression in the hippocampus was examined using microarray analysis. Genes that were significantly (p < 0.05, q < 0.1) differentially expressed were further evaluated. Bioinformatic analyses were predominantly performed using tools available at GeneNetwork.org, and included gene ontology, presence of cis-regulation or polymorphisms, phenotype correlations, and principal component analyses. Comparisons of differential gene expression between groups showed little overlap. Gene Ontology demonstrated distinct biological processes in each group with the combined exposure (RSE) being unique from either the ethanol (NOE) or stress (RSS) group, suggesting that the interaction between these variables is mediated through diverse molecular pathways. This supports the hypothesis that exposure to stress alters ethanol-induced gene expression changes and that exposure to alcohol alters stress-induced gene expression changes. Behavior was profiled in all groups following treatment, and many of the differentially expressed genes are correlated with behavioral variation within experimental groups. Interestingly, in each group several genes were correlated with the same phenotype, suggesting that these genes are the potential origins of significant genetic networks. The distinct sets of differentially expressed genes within each group provide the basis for identifying molecular networks that may aid in understanding the complex interactions between stress and ethanol, and potentially provide relevant therapeutic targets. Using Ptp4a1, a candidate gene underlying the quantitative trait locus for several of these phenotypes, and network analyses, we show that a large group of differentially expressed genes in the NOE group are highly interrelated, some of which have previously been linked to alcohol addiction or alcohol-related phenotypes.

The Prefrontal Cortex as a Critical Gate of Negative Affect and Motivation in Alcohol Use Disorder

The prefrontal cortex (PFC) represents and executes the highest forms of goal-directed behavior, and has thereby attained a central neuroanatomical position in most pathophysiological conceptualizations of motivational disorders, including alcohol use disorder (AUD). Excessive, intermittent exposure to alcohol produces an allostatic dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis along with heightened forebrain glucocorticoid signaling that can damage PFC architecture and function. Negative affective states intimately associated with the transition to alcohol dependence result not only from a dysregulated HPA axis, but also from the inability of a damaged PFC to regulate subcortical stress and reinforcement centers, including the ventral striatum and amygdala. Several cognitive symptoms commonly associated with severe AUD, ranging from poor risk management to the cognitive/affective dimension of pain, are likely mediated by altered function of key anatomical elements that modulate PFC executive function, including contributions from the cingulate cortex and insula. Future therapeutic strategies for severe AUD should focus on attenuating the deleterious effects of excessive stress hormone activity on cognitive/affective and motivational behaviors gated by the PFC.

Severity of alcohol dependence is negatively related to hypothalamic and prefrontal cortical gray matter density in heavy drinking smokers

BACKGROUND

While research has examined brain structure in individuals who use alcohol or nicotine, heavy drinking smokers comprise a unique subpopulation of substance users for whom less is known about the relationship between alcohol or nicotine use and structural brain abnormalities.

OBJECTIVES

The present study examined gray matter morphometry in a sample of 39 heavy drinking smokers (24 males, 15 females) in relation to alcohol and nicotine dependence and quantity of use.

METHODS

Traditional voxel-based morphometry techniques were employed for preprocessing of imaging data. One multiple regression analysis for alcohol and nicotine dependence severity and another for alcohol and nicotine quantity of use were conducted, while controlling for age, gender, and total intracranial volume (ICV).

RESULTS

Alcohol dependence severity was significantly negatively associated with gray matter density in the hypothalamus (p < 0.001, uncorrected) and the right superior frontal gyrus (p < 0.001, uncorrected), while controlling for nicotine dependence severity, age, gender, and ICV. There were no significant relationships observed with respect to nicotine dependence severity, the quantity of alcohol use, or the quantity of nicotine use variables and gray matter density.

CONCLUSIONS

These findings suggest that within heavy drinking smokers, alcohol dependence severity is significantly related to alterations in brain structure, while this effect is not seen for the quantity of alcohol or nicotine use, or severity of nicotine dependence. The current findings help clarify the contribution of alcohol and nicotine effects on brain structure, which could aid in understanding their neurocognitive consequences in heavy drinking smokers.

An Update on CRF Mechanisms Underlying Alcohol Use Disorders and Dependence

Alcohol is the most commonly used and abused substance worldwide. The emergence of alcohol use disorders, and alcohol dependence in particular, is accompanied by functional changes in brain reward and stress systems, which contribute to escalated alcohol drinking and seeking. Corticotropin-releasing factor (CRF) systems have been critically implied in the transition toward problematic alcohol drinking and alcohol dependence. This review will discuss how dysregulation of CRF function contributes to the vulnerability for escalated alcohol drinking and other consequences of alcohol consumption, based on preclinical evidence. CRF signaling, mostly via CRF1 receptors, seems to be particularly important in conditions of excessive alcohol taking and seeking, including during early and protracted withdrawal, relapse, as well as during withdrawal-induced anxiety and escalated aggression promoted by alcohol. Modulation of CRF1 function seems to exert a less prominent role over low to moderate alcohol intake, or to species-typical behaviors. While CRF mechanisms in the hypothalamic-pituitary-adrenal axis have some contribution to the neurobiology of alcohol abuse and dependence, a pivotal role for extra-hypothalamic CRF pathways, particularly in the extended amygdala, is well characterized. More recent studies further suggest a direct modulation of brain reward function by CRF signaling in the ventral tegmental area, nucleus accumbens, and the prefrontal cortex, among other structures. This review will further discuss a putative role for other components of the CRF system that contribute for the overall balance of CRF function in reward and stress pathways, including CRF2 receptors, CRF-binding protein, and urocortins, a family of CRF-related peptides.

Sustained Effects of Developmental Exposure to Ethanol on Zebrafish Anxiety-Like Behaviour

In zebrafish developmentally exposed to ambient ethanol (20mM-50mM) 1–9 days post fertilization (dpf), the cortisol response to stress has been shown to be significantly attenuated in larvae, juveniles and 6 month old adults. These data are somewhat at variance with similar studies in mammals, which often show heightened stress responses. To test whether these cortisol data correlate with behavioural changes in treated animals, anxiety-like behaviour of zebrafish larvae (9dpf and 10dpf) and juveniles (23dpf) was tested in locomotor assays designed to this end. In open field tests treated animals were more exploratory, spending significantly less time at the periphery of the arena. Behavioural effects of developmental exposure to ethanol were sustained in 6-month-old adults, as judged by assessment of thigmotaxis, novel tank diving and scototaxis. Like larvae and juveniles, developmentally treated adults were generally more exploratory, and spent less time at the periphery of the arena in thigmotaxis tests, less time at the bottom of the tank in the novel tank diving tests, and less time in the dark area in scototaxis tests. The conclusion that ethanol-exposed animals showed less anxiety-like behaviour was validated by comparison with the effects of diazepam treatment, which in thigmotaxis and novel tank diving tests had similar effects to ethanol pretreatment. There is thus a possible link between the hypophyseal-pituitary-interrenal axis and the behavioural actions of developmental ethanol exposure. The mechanisms require further elucidation.

Behavioral Neuroadaptation to Alcohol: From Glucocorticoids to Histone Acetylation

A prime mechanism that contributes to the development and maintenance of alcoholism is the dysregulation of the hypothalamic-pituitary-adrenal axis activity and the release of glucocorticoids (cortisol in humans and primates, corticosterone in rodents) from the adrenal glands. In the brain, sustained, local elevation of glucocorticoid concentration even long after cessation of chronic alcohol consumption compromises functional integrity of a circuit, including the prefrontal cortex (PFC), the hippocampus (HPC), and the amygdala (AMG). These structures are implicated in learning and memory processes as well as in orchestrating neuroadaptive responses to stress and anxiety responses. Thus, potentiation of anxiety-related neuroadaptation by alcohol is characterized by an abnormally AMG hyperactivity coupled with a hypofunction of the PFC and the HPC. This review describes research on molecular and epigenetic mechanisms by which alcohol causes distinct region-specific adaptive changes in gene expression patterns and ultimately leads to a variety of cognitive and behavioral impairments on prefrontal- and hippocampal-based tasks. Alcohol-induced neuroadaptations involve the dysregulation of numerous signaling cascades, leading to long-term changes in transcriptional profiles of genes, through the actions of transcription factors such as [cAMP response element-binding protein (CREB)] and chromatin remodeling due to posttranslational modifications of histone proteins. We describe the role of prefrontal-HPC-AMG circuit in mediating the effects of acute and chronic alcohol on learning and memory, and region-specific molecular and epigenetic mechanisms involved in this process. This review first discusses the importance of brain region-specific dysregulation of glucocorticoid concentration in the development of alcohol dependence and describes how persistently increased glucocorticoid levels in PFC may be involved in mediating working memory impairments and neuroadaptive changes during withdrawal from chronic alcohol intake. It then highlights the role of cAMP-PKA-CREB signaling cascade and histone acetylation within the PFC and limbic structures in alcohol-induced anxiety and behavioral impairments, and how an understanding of functional alterations of these pathways might lead to better treatments for neuropsychiatric disorders.

Divergent regulation of distinct glucocorticoid systems in alcohol dependence

Chronic alcohol consumption disrupts glucocorticoid signaling at multiple physiological levels to interact with several disease-related processes associated with neuroendocrine and psychiatric disorders. Excessive alcohol use produces stress-related neuroadaptations at the level of the hypothalamic-pituitary-adrenal (HPA) axis as well as within central (extra-hypothalamic) neural circuitry, including the central amygdala (CeA) and prefrontal cortex (PFC). Altered glucocorticoid receptor (GR) signaling in these areas following excessive alcohol exposure is postulated to mediate the transition from recreational drinking to dependence, as well as the manifestation of a host of cognitive and neurological deficits. Specifically, a bidirectional regulation of stress systems by glucocorticoids leads to the development of an HPA axis tolerance and a concomitant sensitization of cortical and subcortical circuitries. A greater understanding of how hypothalamic and extra-hypothalamic glucocorticoid systems interact to mediate excessive drinking and related pathologies will lead to more effective therapeutic strategies for alcohol use disorder (AUD) and closely related comorbidities.

Sustained action of developmental ethanol exposure on the cortisol response to stress in zebrafish larvae and adults

Background

Ethanol exposure during pregnancy is one of the leading causes of preventable birth defects, leading to a range of symptoms collectively known as fetal alcohol spectrum disorder. More moderate levels of prenatal ethanol exposure lead to a range of behavioural deficits including aggression, poor social interaction, poor cognitive performance and increased likelihood of addiction in later life. Current theories suggest that adaptation in the hypothalamo-pituitary-adrenal (HPA) axis and neuroendocrine systems contributes to mood alterations underlying behavioural deficits and vulnerability to addiction. In using zebrafish (Danio rerio), the aim is to determine whether developmental ethanol exposure provokes changes in the hypothalamo-pituitary-interrenal (HPI) axis (the teleost equivalent of the HPA), as it does in mammalian models, therefore opening the possibilities of using zebrafish to elucidate the mechanisms involved, and to test novel therapeutics to alleviate deleterious symptoms.

Results and Conclusions

The results showed that developmental exposure to ambient ethanol, 20mM-50mM 1-9 days post fertilisation, had immediate effects on the HPI, markedly reducing the cortisol response to air exposure stress, as measured by whole body cortisol content. This effect was sustained in adults 6 months later. Morphology, growth and locomotor activity of the animals were unaffected, suggesting a specific action of ethanol on the HPI. In this respect the data are consistent with mammalian results, although they contrast with the higher corticosteroid stress response reported in rats after developmental ethanol exposure. The mechanisms that underlie the specific sensitivity of the HPI to ethanol require elucidation.

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.

FKBP5 moderates alcohol withdrawal severity: human genetic association and functional validation in knockout mice

Alcohol withdrawal is associated with hypothalamic-pituitary-adrenal (HPA) axis dysfunction. The FKBP5 gene codes for a co-chaperone, FK506-binding protein 5, that exerts negative feedback on HPA axis function. This study aimed to examine the effects of single-nucleotide polymorphisms (SNPs) of the FKBP5 gene in humans and the effect of Fkbp5 gene deletion in mice on alcohol withdrawal severity. We genotyped six FKBP5 SNPs (rs3800373, rs9296158, rs3777747, rs9380524, rs1360780, and rs9470080) in 399 alcohol-dependent inpatients with alcohol consumption 48 h before admission and recorded scores from the Clinical Institute Withdrawal Assessment-Alcohol revised (CIWA-Ar). Fkbp5 gene knockout (KO) and wild-type (WT) mice were assessed for alcohol withdrawal using handling-induced convulsions (HICs) following both acute and chronic alcohol exposure. We found the minor alleles of rs3800373 (G), rs9296158 (A), rs1360780 (T), and rs9470080 (T) were significantly associated with lower CIWA-Ar scores whereas the minor alleles of rs3777747 (G) and rs9380524 (A) were associated with higher scores. The haplotype-based analyses also showed an association with alcohol withdrawal severity. Fkbp5 KO mice showed significantly greater HICs during withdrawal from chronic alcohol exposure compared with WT controls. This study is the first to show a genetic effect of FKBP5 on the severity of alcohol withdrawal syndrome. In mice, the absence of the Fkbp5 gene enhances sensitivity to alcohol withdrawal. We suggest that FKBP5 variants may trigger different adaptive changes in HPA axis regulation during alcohol withdrawal with concomitant effects on withdrawal severity.

The "Prediction of Alcohol Withdrawal Severity Scale" (PAWSS): systematic literature review and pilot study of a new scale for the prediction of complicated alcohol withdrawal syndrome

BACKGROUND

To date, no screening tools for alcohol withdrawal syndromes (AWS) have been validated in the medically ill. Although several tools quantify the severity of AWS (e.g., Clinical Institute Withdrawal Assessment for Alcohol [CIWA]), none identify subjects at risk of AWS, thus missing the opportunity for timely prophylaxis. Moreover, there are no validated tools for the prediction of complicated (i.e., moderate to severe) AWS in the medically ill.

OBJECTIVES

Our goals were (1) to conduct a systematic review of the published literature on AWS to identify clinical factors associated with the development of AWS, (2) to use the identified factors to develop a tool for the prediction of alcohol withdrawal among patients at risk, and (3) to conduct a pilot study to assess the validity of the tool.

METHODS

For the creation of the Prediction of Alcohol Withdrawal Severity Scale (PAWSS), we conducted a systematic literature search using PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines for clinical factors associated with the development of AWS, using PubMed, PsychInfo, MEDLINE, and Cochrane Databases. Eligibility criteria included: (i) manuscripts dealing with human subjects, age 18 years or older, (ii) manuscripts directly addressing descriptions of AWS or its predisposing factors, including case reports, naturalistic case descriptions, and all types of clinical trials (e.g., randomized, single-blind, or open label studies), (iii) manuscripts describing characteristics of alcohol use disorder (AUD), and (iv) manuscripts dealing with animal data (which were considered only if they directly dealt with variables described in humans). Obtained data were used to develop the Prediction of Alcohol Withdrawal Severity Scale, in order to assist in the identification of patients at risk for complicated AWS. A pilot study was conducted to assess the new tool's psychometric qualities on patients admitted to a general inpatient medicine unit over a 2-week period, who agreed to participate in the study. Blind to PAWSS results, a separate group of researchers retrospectively examined the medical records for evidence of AWS.

RESULTS

The search produced 2802 articles describing factors potentially associated with increased risk for AWS, increased severity of withdrawal symptoms, and potential characteristics differentiating subjects with various forms of AWS. Of these, 446 articles met inclusion criteria and underwent further scrutiny, yielding a total of 233 unique articles describing factors predictive of AWS. A total of 10 items were identified as correlated with complicated AWS (i.e., withdrawal hallucinosis, withdrawal-related seizures, and delirium tremens) and used to construct the PAWSS. During the pilot study, a total of 68 subjects underwent evaluation with PAWSS. In this pilot sample the sensitivity, specificity, and positive and negative predictive values of PAWSS were 100%, using the threshold score of 4.

DISCUSSION

The results of the literature search identified 10 items which may be correlated with risk for complicated AWS. These items were assembled into a tool to assist in the identification of patients at risk: PAWSS. The results of this pilot study suggest that PAWSS may be useful in identifying risk of complicated AWS in medically ill, hospitalized individuals. PAWSS is the first validated tool for the prediction of severe AWS in the medically ill and its use may aid in the early identification of patients at risk for complicated AWS, allowing for prophylaxis against AWS before severe alcohol withdrawal syndromes develop.

Neurochemical mechanisms of alcohol withdrawal

Alcohol dependence encompasses a serious medical and societal problem that constitutes a major public health concern. A serious consequence of dependence is the emergence of symptoms associated with the alcohol withdrawal syndrome when drinking is abruptly terminated or substantially reduced. Clinical features of alcohol withdrawal include signs of central nervous system hyperexcitability, heightened autonomic nervous system activation, and a constellation of symptoms contributing to psychologic discomfort and negative affect. The development of alcohol dependence is a complex and dynamic process that ultimately reflects a maladaptive neurophysiologic state. Perturbations in a wide range of neurochemical systems, including glutamate, γ-aminobutyric acid, monoamines, a host of neuropeptide systems, and various ion channels produced by the chronic presence of alcohol ultimately compromise the functional integrity of the brain. These neuroadaptations not only underlie the emergence and expression of many alcohol withdrawal symptoms, but also contribute to enhanced relapse vulnerability as well as perpetuation of uncontrolled excessive drinking. This chapter highlights the hallmark features of the alcohol withdrawal syndrome, and describes neuroadaptations in a wide array of neurotransmitter and neuromodulator systems (amino acid and monoamine neurotransmitter, neuropeptide systems, and various ion channels) as they relate to the expression of various signs and symptoms of alcohol withdrawal, as well as their relationship to the significant clinical problem of relapse and uncontrolled dangerous drinking.

Addiction and the adrenal cortex

Substantial evidence shows that the hypophyseal–pituitary–adrenal (HPA) axis and corticosteroids are involved in the process of addiction to a variety of agents, and the adrenal cortex has a key role. In general, plasma concentrations of cortisol (or corticosterone in rats or mice) increase on drug withdrawal in a manner that suggests correlation with the behavioural and symptomatic sequelae both in man and in experimental animals. Corticosteroid levels fall back to normal values in resumption of drug intake. The possible interactions between brain corticotrophin releasing hormone (CRH) and proopiomelanocortin (POMC) products and the systemic HPA, and additionally with the local CRH–POMC system in the adrenal gland itself, are complex. Nevertheless, the evidence increasingly suggests that all may be interlinked and that CRH in the brain and brain POMC products interact with the blood-borne HPA directly or indirectly. Corticosteroids themselves are known to affect mood profoundly and may themselves be addictive. Additionally, there is a heightened susceptibility for addicted subjects to relapse in conditions that are associated with change in HPA activity, such as in stress, or at different times of the day. Recent studies give compelling evidence that a significant part of the array of addictive symptoms is directly attributable to the secretory activity of the adrenal cortex and the actions of corticosteroids. Additionally, sex differences in addiction may also be attributable to adrenocortical function: in humans, males may be protected through higher secretion of DHEA (and DHEAS), and in rats, females may be more susceptible because of higher corticosterone secretion.

Characterization of functional polymorphisms and glucocorticoid-responsive elements in the promoter of TDO2, a candidate gene for ethanol-induced behavioural disorders

AIMS

In response to acute ethanol consumption, tryptophan 2,3-dioxygenase (TDO) induces the kynurenine pathway (KP) through a glucocorticoid-mediated mechanism, which could lead to a dramatic accumulation of neurotoxic metabolites in association with serotonin depletion. As a result, interindividual variability in ethanol-induced behavioural disorders, such as black-outs and violent impulsive behaviours (BOVIBs) following binge drinking, could be partly explained by genetic polymorphisms affecting the KP. The aim of this study was to identify polymorphisms on the promoter of the TDO2 gene that could affect expression and/or activity of TDO through glucocorticoid induction.

METHODS

Polymorphisms were screened using a PCR-sequencing strategy applied to 31 alcohol-dependent patients and 49 unrelated healthy volunteers, and functionally analysed with bioinformatic prediction tools and gene reporter assays in HepG2 and A549 cell lines.

RESULTS

We identified 12 polymorphisms in the human TDO2 promoter region, 2 of them corresponding to previously unknown single-nucleotide polymorphisms (SNPs) and 3 of them located in putative glucocorticoid-responsive elements (GREs). Gene reporter assays using HepG2 and A549 cell lines confirmed the presence of several functional GREs in the promoter region of TDO2 and revealed that some of the identified polymorphisms affect the promoter activity under glucocorticoid receptor over-expression and dexamethasone exposure conditions.

CONCLUSIONS

Correlational studies in larger samples could help to determine whether these polymorphisms are responsible for variations of expression and/or activity of TDO, in particular under conditions where release of glucocorticoids is increased, such as acute ethanol intake. If confirmed, such results would be of major interest in explaining part of the interindividual variability observed in behavioural responses to acute ethanol consumption.

The role of the glucocorticoids in developing resilience to stress and addiction

There is emerging evidence that individuals have the capacity to learn to be resilient by developing protective mechanisms that prevent them from the maladaptive effects of stress that can contribute to addiction. The emerging field of the neuroscience of resilience is beginning to uncover the circuits and molecules that protect against stress-related neuropsychiatric diseases, such as addiction. Glucocorticoids (GCs) are important regulators of basal and stress-related homeostasis in all higher organisms and influence a wide array of genes in almost every organ and tissue. GCs, therefore, are ideally situated to either promote or prevent adaptation to stress. In this review, we will focus on the role of GCs in the hypothalamic-pituitary adrenocortical axis and extra-hypothalamic regions in regulating basal and chronic stress responses. GCs interact with a large number of neurotransmitter and neuropeptide systems that are associated with the development of addiction. Additionally, the review will focus on the orexinergic and cholinergic pathways and highlight their role in stress and addiction. GCs play a key role in promoting the development of resilience or susceptibility and represent important pharmacotherapeutic targets that can reduce the impact of a maladapted stress system for the treatment of stress-induced addiction.

Chronic ethanol potentiates the effect of neuropeptide s in the basolateral amygdala and shows increased anxiolytic and anti-depressive effects

Alleviating anxiety and depression is pivotal for reducing the risk of relapse in alcoholics. Currently available anxiolytic treatments are limited by side effects, including reduced efficacy in alcoholics, addiction, and sedation. We examined whether the neuropeptide S receptor (NPSR) was effective at controlling ethanol consumption and the anxiety and depression produced by forced abstinence from ethanol. We found that the anxiolytic and anti-depressant effects of NPS are enhanced in acute ethanol abstinent mice. In addition, we found that NPS reduced ethanol consumption and is not in and of itself rewarding. We also provide evidence that ethanol consumption increases the ability of NPS to modulate neuronal activity in the basolateral amygdala. Finally, we found that local injection of NPS in the basolateral amygdala promotes anxiolysis after chronic ethanol consumption, thereby providing insight into the molecular mechanism underlying the changes in behavioral response to NPS. In light of the improved anxiolytic efficacy and benign side effects of NPS in ethanol-withdrawn animals, the NPSR may prove a suitable target for reducing relapse in alcoholism.

Natural plant products and extracts that reduce immunoexcitotoxicity-associated neurodegeneration and promote repair within the central nervous system

Our understanding of the pathophysiological and biochemical basis of a number of neurological disorders has increased enormously over the last three decades. Parallel with this growth of knowledge has been a clearer understanding of the mechanism by which a number of naturally occurring plant extracts, as well as whole plants, can affect these mechanisms so as to offer protection against injury and promote healing of neurological tissues. Curcumin, quercetin, green tea catechins, balcalein, and luteolin have been extensively studied, and they demonstrate important effects on cell signaling that go far beyond their antioxidant effects. Of particular interest is the effect of these compounds on immunoexcitotoxicity, which, the authors suggest, is a common mechanism in a number of neurological disorders. By suppressing or affecting microglial activation states as well as the excitotoxic cascade and inflammatory mediators, these compounds dramatically affect the pathophysiology of central nervous system disorders and promote the release and generation of neurotrophic factors essential for central nervous system healing. We discuss the various aspects of these processes and suggest future directions for study.

Stress and the HPA axis: role of glucocorticoids in alcohol dependence

Stress has long been suggested to be an important correlate of uncontrolled drinking and relapse. An important hormonal response system to stress-the hypothalamic-pituitary-adrenal (HPA) axis-may be involved in this process, particularly stress hormones known as glucocorticoids and primarily cortisol. The actions of this hormone system normally are tightly regulated to ensure that the body can respond quickly to stressful events and return to a normal state just as rapidly. The main determinants of HPA axis activity are genetic background, early-life environment, and current life stress. Alterations in HPA axis regulation are associated with problematic alcohol use and dependence; however, the nature of this dysregulation appears to vary with respect to stage of alcohol dependence. Much of this research has focused specifically on the role of cortisol in the risk for, development of, and relapse to chronic alcohol use. These studies found that cortisol can interact with the brain's reward system, which may contribute to alcohol's reinforcing effects. Cortisol also can influence a person's cognitive processes, promoting habit-based learning, which may contribute to habit formation and risk of relapse. Finally, cortisol levels during abstinence may be useful clinical indicators of relapse vulnerability in alcohol-dependent people.