Ethanol-induced Changes Research Articles

Pleiotrophin Overexpression Reduces Adolescent Ethanol Consumption and Modulates Ethanol-Induced Glial Responses and Changes in the Perineuronal Nets in the Mouse Hippocampus.

To investigate whether pleiotrophin (PTN) overexpression influences ethanol consumption during adolescence and its effects on glial responses, neurogenesis, and perineuronal nets (PNNs) in the mouse hippocampus. Male and female adolescent transgenic mice with elevated PTN levels (Ptn-Tg) and controls underwent an intermittent access to ethanol (IAE) 2-bottle choice protocol. Ethanol consumption, PTN levels, neurogenesis, and glial responses were measured in the hippocampus. Immunohistochemistry was used to assess changes in new neurons, microglial and astrocyte populations, and PNNs. Ptn-Tg mice consumed significantly less ethanol compared to controls, irrespective of sex. Chronic alcohol exposure reduced PTN levels in the hippocampus. PTN overexpression decreased the number of new neurons in the dentate gyrus (DG) and prevented ethanol-induced microglial activation. Ptn-Tg mice had significantly more astrocytes and fewer PNNs, with a higher percentage of parvalbumin (PV) positive cells surrounded by PNNs under basal conditions. However, ethanol drastically reduced the number of PV+ cells in the DG of Ptn-Tg mice, despite the presence of PNNs. PTN overexpression reduces adolescent ethanol consumption and influences ethanol-induced effects on hippocampal neurogenesis, glial responses, and PNN remodeling. These findings underscore the importance of PTN in modulating alcohol-induced neurotoxicity.

Lipid droplet-associated proteins in alcohol-associated fatty liver disease: A proteomic approach.

The earliest manifestation of alcohol-associated liver disease (ALD) is steatosis characterized by deposition of fat in specialized organelles called lipid droplets (LDs). While alcohol administration causes a rise in LD numbers in the hepatocytes, little is known regarding their characteristics that allow their accumulation and size to increase. The aim of the present study is to gain insights into underlying pathophysiological mechanisms by investigating the ethanol-induced changes in hepatic LD proteome as a function of LD size. Adult male Wistar rats (180-200 g BW) were fed with ethanol liquid diet for 6 weeks. At sacrifice, large-, medium-, and small-sized hepatic LD subpopulations (LD1, LD2, and LD3, respectively) were isolated and subjected to morphological and proteomic analyses. Morphological analysis of LD1-LD3 fractions of ethanol-fed rats clearly demonstrated that LD1 contained larger LDs compared with LD2 and LD3 fractions. Our preliminary results from principal component analysis showed that the proteome of different-sized hepatic LD fractions was distinctly different. Proteomic data analysis identified over 2000 proteins in each LD fraction with significant alterations in protein abundance among the three LD fractions. Among the altered proteins, several were related to fat metabolism, including synthesis, incorporation of fatty acid, and lipolysis. Ingenuity pathway analysis revealed increased fatty acid synthesis, fatty acid incorporation, LD fusion, and reduced lipolysis in LD1 compared to LD3. Overall, the proteomic findings indicate that the increased level of protein that facilitates fusion of LDs combined with an increased association of negative regulators of lipolysis dictates the generation of large-sized LDs during the development of alcohol-associated hepatic steatosis. Several significantly altered proteins were identified in different-sized LDs isolated from livers of ethanol-fed rats. Ethanol-induced increases in specific proteins that hinder LD lipid metabolism led to the accumulation and persistence of large-sized LDs in the liver.

Selenium Attenuates Ethanol-induced Hepatocellular Injury by Regulating Ferroptosis and Apoptosis.

Ferroptosis is a newly identified type of cell death which is strongly linked to the development of several diseases. Whereas, the role of ferroptosis in the improvement of ethanol-induced hepatocytes injury by selenium has not been confirmed. In this study, an in vitro cell damage model was established using half inhibition concentration of ethanol to induce NCTC clone 1469. Cell activity, lipid peroxidation, apoptosis and the expression of markers related to ferroptosis pathway was determined. A mouse model of alcoholic liver disease (ALD) was constructed and the effectiveness of selenium and ferrostatin-1 in treating ALD in vivo was assessed by serum liver function tests, tissue staining and immunohistochemistry for ferroptosis related proteins. Pretreatment with selenomethionine and ebselen significantly improved ethanol-induced reduction in hepatocyte viability, elevated GSH levels and SOD enzyme activity, reduced MDA and iron content, while improving ethanol-induced changes in apoptosis levels and ferroptosis markers GPX4, SLC7A11, and ACSL4, with the effect of Selenomethionine being more significant. In vivo results also indicated that intervention with selenium or ferroptosis inhibitors significantly improved ethanol-induced liver tissue damage, significantly reduced serum ALT and AST levels, upregulated GPX4 and SLC7A11, but reduced ACSL4 protein levels in liver tissue. The process of ethanol damage to hepatocytes is regulated by the ferroptosis pathway. Selenium may exert a beneficial role in ethanol-induced hepatocyte injury by antagonizing oxidative stress and regulating apoptosis and ferroptosis pathways.

Ethanol-related transcriptomic changes in mouse testes

BackgroundAlcohol consumption is widely known to have detrimental effects on various organs and tissues. The effects of ethanol on male reproduction have been studied at the physiological and cellular levels, but no systematic study has examined the effects of ethanol on male reproduction-related gene expression.ResultsWe employed a model of chronic ethanol administration using the Lieber-DeCarli diet. Ethanol-fed mice showed normal testicular and epididymal integrity, and sperm morphology, but decreased sperm count. Total RNA sequencing analysis of testes from ethanol-fed mice showed that a small fraction (∼ 2%) of testicular genes were differentially expressed in ethanol-fed mice and that, of these genes, 28% were cell-type specific in the testis. Various in silico analyses were performed, and gene set enrichment analysis revealed that sperm tail structure-related genes, including forkhead box J1 (Foxj1), were down-regulated in testes of ethanol-fed mice. Consistent with this result, ethanol-fed mice exhibited decreased sperm motility.ConclusionThis study provides the first comprehensive transcriptomic profiling of ethanol-induced changes in the mouse testis, and suggests gene expression profile changes as a potential mechanism underlying ethanol-mediated reproductive dysfunction, such as impaired sperm motility.

Effects of Methanol Extract of Celery (Apium graveolens) Leaf on Ethanol-Induced Left Ventricular Changes in Wistar Rats

Background: Alcohol consumption is associated with several cardiovascular diseases such as heart failure, left ventricular hypertrophy, as well as with other disorders. This study was designed to determine the cardioprotective effect of celery (Apium graveolens) extract in attenuating perturbations arising from alcohol ingestion on left ventricular injury in adult Wistar rats.  Methods: Thirty male Wistar rats weighing 120g -160g were used for this study. The rats were divided into six (6) groups A, B, C, D, E &F five (5) rats each. The rats in group (A) served as control and received standard pellet, while groups B, C, D, E and F were administered orally with 8ml/kg b. w of ethanol and 100mg/kg, 150mg/kg, 200mg/kg of methanol extract of Apium graveolens (MEAG) were given to group C, D and E and 25mg of propranolol was given to group F orally. Group A and B were administered with 2ml/kg b. w distilled water.  Results: The relative heart weight, level of serum cardiac troponin I and left ventricular wall thickness of the ethanol-induced rats were significantly increase (F = 7.64; p = 0.002), (F = 22.66; p = 0.001) and (F = 85.29; p < 0.001) when compared with the control and across all experimental groups in this study. Group treated with MEAG also showed regular striations.Conclusion: This study indicates that MEAG has cardioprotective effects on these perturbations.

Ethanol-induced lung and cardiac right ventricular inflammation and remodeling underlie progression to pulmonary arterial hypertension.

Current research on ethanol-induced cardiovascular anomalies has focused on left ventricular (LV) function and blood pressure. To extend this area of research, we sought to determine whether ethanol-induced alterations in the structure and function of the right cardiac ventricle (RV) and pulmonary artery (PA) lead to pulmonary arterial hypertension (PAH). Two groups of male Sprague-Dawley rats received a balanced liquid diet containing 5% ethanol (w/v) or a pair-fed isocaloric liquid diet for 8 weeks. Weekly echocardiography was conducted to evaluate cardiopulmonary function, and lung and RV tissues were collected for exvivo histological and molecular studies. The ethanol-treated rats exhibited: (1) Elevated mean pulmonary arterial pressure and decreased pulmonary artery acceleration time/ejection time; (2) Pulmonary vascular remodeling comprising intrapulmonary artery medial layer thickening; and (3) RV hypertrophy along with increased RV/LV + septum, RV diameter, RV cardiomyocyte cross-sectional area, and LV mass/body weight ratio. These responses were associated with increased lung and RV pro-inflammatory markers, endothelin-1 (ET-1), TNF-α, and IL-6 levels and higher ET-1,ET-1 type A/B receptor ratio, and downregulation of the cytoprotective protein, bone morphogenetic protein receptor 2 (BMPR2), in the lungs. These findings show that moderate ethanol-induced cardiopulmonary changes underlie progression to PAH via an upregulated proinflammatory ET1-TNFα-IL6 pathway and suppression of the anti-inflammatory BMPR2.

Tributyrin Supplementation Rescues Chronic-Binge Ethanol-Induced Oxidative Stress in the Gut-Lung Axis in Mice.

Excessive alcohol consumption increases the severity and worsens outcomes of pulmonary infections, often due to oxidative stress and tissue damage. While the mechanism behind this relationship is multifaceted, recent evidence suggests ethanol-induced changes to the gut microbiome impact the gut-lung axis. To assess this, a chronic-binge ethanol feeding mouse model was used to determine how ethanol altered the gut microbiome, small intestinal epithelial barrier, and immune responses, as well as neutrophil abundance and oxidative stress in the lungs, and how supporting gut health with tributyrin supplementation during chronic-binge ethanol exposure affected these responses. We found that ethanol consumption altered gut bacterial taxa and metabolic processes, distorted small intestinal immune responses, and induced both bacteria and endotoxin translocation into the lymphatic and circulatory systems. These changes were associated with increased neutrophil (Ly6G) presence and markers of oxidative stress, lipocalin-2 and myeloperoxidase, in the lungs. Importantly, tributyrin supplementation during ethanol exposure rescued gut bacterial function (p < 0.05), small intestinal barrier integrity, and immune responses, as well as reducing both Ly6G mRNA (p < 0.05) and lipocalin-2 mRNA (p < 0.01) in the lungs. These data suggest ethanol-associated disruption of gut homeostasis influenced the health of the lungs, and that therapeutics supporting gut health may also support lung health.

Osmolyte-specific counteraction of ethanol-induced aggregation and structure-function distortion of catalase

Catalase, an industrially important enzyme, was found to unfold and aggregate in presence of ethanol. Aggregation of catalase was observed in 20% and higher ethanol concentrations as evident by typical light scattering aggregation profile with complete absence of lag phase, enhanced Thioflavin T fluorescence, increased 8-anilinonaphthalene-1-sulfonic acid binding depicting enhanced hydrophobic exposure, unfolded tertiary structure with an altered Fourier transform infrared and soret spectra. To prevent ethanol-induced aggregation of catalase, osmolytes were screened for their ability to counteract the ethanol effects on catalase. Among all the osmolytes tested, only three i.e., betaine, trehalose and sucrose counteracted the ethanol-induced aggregation of catalase by about 30–50%. Results infer that addition of osmolytes to ethanol-treated catalase persuaded changes in solvent polarity and protein microenvironment leading to overall counteraction of ethanol-induced structural changes in catalase responsible for its aggregation. Fluorescence microscopy also confirmed the counteraction of ethanol-induced aggregation by osmolytes as evident from the decreased presence of aggregates in osmolyte-incubated ethanol-treated catalase. Overall, the osmolyte-induced counteraction of ethanol effects on catalase is biologically significant as it provides significant insights regarding the prevention of organic solvent induced aggregation of industrially important enzymes, being otherwise vulnerable to the solvent-induced distortion of their structure-function integrity.

Upregulated GIRK2 Counteracts Ethanol-Induced Changes in Excitability and Respiration in Human Neurons.

Genome-wide association studies (GWAS) of electroencephalographic endophenotypes for alcohol use disorder (AUD) has identified noncoding polymorphisms within the KCNJ6 gene. KCNJ6 encodes GIRK2, a subunit of a G-protein-coupled inwardly rectifying potassium channel that regulates neuronal excitability. We studied the effect of upregulating KCNJ6 using an isogenic approach with human glutamatergic neurons derived from induced pluripotent stem cells (male and female donors). Using multielectrode arrays, population calcium imaging, single-cell patch-clamp electrophysiology, and mitochondrial stress tests, we find that elevated GIRK2 acts in concert with 7-21 d of ethanol exposure to inhibit neuronal activity, to counteract ethanol-induced increases in glutamate response, and to promote an increase intrinsic excitability. Furthermore, elevated GIRK2 prevented ethanol-induced changes in basal and activity-dependent mitochondrial respiration. These data support a role for GIRK2 in mitigating the effects of ethanol and a previously unknown connection to mitochondrial function in human glutamatergic neurons.

Acetic Acid: An Underestimated Metabolite in Ethanol-Induced Changes in Regulating Cardiovascular Function.

Acetic acid is a bioactive short-chain fatty acid produced in large quantities from ethanol metabolism. In this review, we describe how acetic acid/acetate generates oxidative stress, alters the function of pre-sympathetic neurons, and can potentially influence cardiovascular function in both humans and rodents after ethanol consumption. Our recent findings from in vivo and in vitro studies support the notion that administration of acetic acid/acetate generates oxidative stress and increases sympathetic outflow, leading to alterations in arterial blood pressure. Real-time investigation of how ethanol and acetic acid/acetate modulate neural control of cardiovascular function can be conducted by microinjecting compounds into autonomic control centers of the brain and measuring changes in peripheral sympathetic nerve activity and blood pressure in response to these compounds.

A critical review of ethanol effects on neuronal firing: A metabolic perspective.

Ethanol metabolism is relatively understudied in neurons, even though changes in neuronal metabolism are known to affect their activity. Recent work demonstrates that ethanol is preferentially metabolized over glucose as a source of carbon and energy, and it reprograms neurons to a state of reduced energy potential and diminished capacity to utilize glucose once ethanol is exhausted. Ethanol intake has been associated with changes in neuronal firing and specific brain activity (EEG) patterns have been linked with risk for alcohol use disorder (AUD). Furthermore, a haplotype of the inwardly rectifying potassium channel subunit, GIRK2, which plays a critical role in regulating excitability of neurons, has been linked with AUD and shown to be directly regulated by ethanol. At the same time, overexpression of GIRK2 prevents ethanol-induced metabolic changes. Based on the available evidence, we conclude thatthe mechanisms underlying the effects of ethanol on neuronal metabolism are a novel target for developing therapies for AUD.

Adolescent binge ethanol impacts H3K9me3-occupancy at synaptic genes and the regulation of oligodendrocyte development.

Binge drinking in adolescence can disrupt myelination and cause brain structural changes that persist into adulthood. Alcohol consumption at a younger age increases the susceptibility of these changes. Animal models to understand ethanol's actions on myelin and white matter show that adolescent binge ethanol can alter the developmental trajectory of oligodendrocytes, myelin structure, and myelin fiber density. Oligodendrocyte differentiation is epigenetically regulated by H3K9 trimethylation (H3K9me3). Prior studies have shown that adolescent binge ethanol dysregulates H3K9 methylation and decreases H3K9-related gene expression in the PFC. Here, we assessed ethanol-induced changes to H3K9me3 occupancy at genomic loci in the developing adolescent PFC. We further assessed ethanol-induced changes at the transcription level with qPCR time course approaches in oligodendrocyte-enriched cells to assess changes in oligodendrocyte progenitor and oligodendrocytes specifically. Adolescent binge ethanol altered H3K9me3 regulation of synaptic-related genes and genes specific for glutamate and potassium channels in a sex-specific manner. In PFC tissue, we found an early change in gene expression in transcription factors associated with oligodendrocyte differentiation that may lead to the later significant decrease in myelin-related gene expression. This effect appeared stronger in males. Further exploration in oligodendrocyte cell enrichment time course and dose response studies could suggest lasting dysregulation of oligodendrocyte maturation at the transcriptional level. Overall, these studies suggest that binge ethanol may impede oligodendrocyte differentiation required for ongoing myelin development in the PFC by altering H3K9me3 occupancy at synaptic-related genes. We identify potential genes that may be contributing to adolescent binge ethanol-related myelin loss.

Understanding the effects of ethanol on the liposome bilayer structure using microfluidic-based time-resolved small-angle X-ray scattering and molecular dynamics simulations.

Lipid nanoparticles (LNPs) are essential carrier particles in drug delivery systems, particularly in ribonucleic acid delivery. In preparing lipid-based nanoparticles, microfluidic-based ethanol injection may produce precisely size-controlled nanoparticles. Ethanol is critical in LNP formation and post-treatment processes and affects liposome size, structure, lamellarity, and drug-loading efficiency. However, the effects of time-dependent changes in the ethanol concentration on the structural dynamics of liposomes are not clearly understood. Herein, we investigated ethanol-induced lipid bilayer changes in liposomes on a time scale from microseconds to tens of seconds using a microfluidic-based small-angle X-ray scattering (SAXS) measurement system coupled with molecular dynamics (MD) simulations. The time-resolved SAXS measurement system revealed that single unilamellar liposomes were converted to multilamellar liposomes within 0.8 s of contact with ethanol, and the d-spacing was decreased from 6.1 (w/o ethanol) to 4.4 nm (80% ethanol) with increasing ethanol concentration. We conducted 1 μs MD simulations to understand the molecular-level structural changes in the liposomes. The MD simulations revealed that the changes in the lamellar structure caused by ethanol at the molecular level could explain the structural changes in the liposomes observed via time-resolved SAXS. Therefore, the post-treatment process to remove residual ethanol is critical in liposome formation.

Insights into the mechanisms underlying ethanol-induced changes in the dough mechanical properties and quality characteristics of fresh noodles

This study investigated the effects of ethanol (0 %∼6%) on the dough mechanical properties and quality characteristics of fresh noodles and elucidated the relationship between the above changes and physicochemical, structural, and molecular properties of gluten. Ethanol reduced the water absorption (from 59.00 % to 52.33 %), stability time (from 8.17 min to 3.33 min) and viscoelasticity of dough, and increased the development time, weakening degree and compliance. Ethanol also decreased the fracture stress of dough sheet, and increased fracture elongation and adhesiveness (from 46.15 g·s to 75.88 g·s). Ethanol decreased the noodles’ hardness (from 5347.41 g to 4442.34 g), break force, tensile distance, and water absorption, while cooking loss was increased. SEM and CLSM showed that ethanol destroyed the compactness of internal structure and inhibited the formation of gluten network in noodles. According to the results of SE-HPLC and RP-HPLC, ethanol dissolved part of the gliadin and inhibited the polymerization of protein.

Spidroins under the Influence of Alcohol: Effect of Ethanol on Secondary Structure and Molecular Level Solvation of Silk-Like Proteins.

Future sustainable materials based on designer biomolecules require control of the solution assembly, but also interfacial interactions. Alcohol treatments of protein materials are an accessible means to this, making understanding of the process at the molecular level of seminal importance. We focus here on the influence of ethanol on spidroins, the main proteins of silk. By large-scale atomistically detailed molecular dynamics (MD) simulations and interconnected experiments, we characterize the protein aggregation, secondary structure changes, molecular level origins of them, and solvation environment changes for the proteins, as induced by ethanol as a solvation additive. The MD and circular dichoroism (CD) findings jointly show that ethanol promotes ordered structure in the protein molecules, leading to an increase of helix content and turns but also increased aggregation, as revealed by dynamic light scattering (DLS) and light microscopy. The structural changes correlate at the molecular level with increased intramolecular hydrogen bonding. The simulations reveal that polar amino acids, such as glutamine and serine, are most influenced by ethanol, whereas glycine residues are most prone to be involved in the ethanol-induced secondary structure changes. Furthermore, ethanol engages in interactions with the hydrophobic alanine-rich regions of the spidroin, significantly decreasing the hydrophobic interactions of the protein with itself and its surroundings. The protein solutes also change the microstructure of water/ethanol mixtures, essentially decreasing the level of larger local clustering. Overall, the work presents a systematic characterization of ethanol effects on a widely used, common protein type, spidroins, and generalizes the findings to other intrinsically disordered proteins by pinpointing the general features of the response. The results can aid in designing effective alcohol treatments for proteins, but also enable design and tuning of protein material properties by a relatively controllable solvation handle, the addition of ethanol.

Ethanol- and PARP-Mediated Regulation of Ribosome-Associated Long Non-Coding RNA (lncRNA) in Pyramidal Neurons.

Although, by definition, long noncoding RNAs (lncRNAs) are not translated, they are sometimes associated with ribosomes. In fact, some estimates suggest the existence of more than 50 K lncRNA molecules that could encode for small peptides. We examined the effects of an ethanol and Poly-ADP Ribose Polymerase (PARP) inhibitor (ABT-888) on ribosome-bound lncRNAs. Mice were administered via intraperitoneal injection (i.p.) either normal saline (CTL) or ethanol (EtOH) twice a day for four consecutive days. On the fourth day, a sub-group of mice administered with ethanol also received ABT-888 (EtOH+ABT). Ribosome-bound lncRNAs in CaMKIIα-expressing pyramidal neurons were measured using the Translating Ribosome Affinity Purification (TRAP) technique. Our findings show that EtOH altered the attachment of 107 lncRNA transcripts, while EtOH+ABT altered 60 lncRNAs. Among these 60 lncRNAs, 49 were altered by both conditions, while EtOH+ABT uniquely altered the attachment of 11 lncRNA transcripts that EtOH alone did not affect. To validate these results, we selected eight lncRNAs (Mir124-2hg, 5430416N02Rik, Snhg17, Snhg12, Snhg1, Mir9-3hg, Gas5, and 1110038B12Rik) for qRT-PCR analysis. The current study demonstrates that ethanol-induced changes in lncRNA attachment to ribosomes can be mitigated by the addition of the PARP inhibitor ABT-888.

Social behavior and neuronal activation in adolescent female Fos-LacZ transgenic rats: Impact of acute ethanol challenge and baseline levels of social preference

In human adolescents, females often report drinking for coping reasons to avoid negative affective states. We have shown previously that adolescent female rats with elevated levels of anxiety-like behavior under social test circumstances, indexed via low social preference, are sensitive to anxiolytic effects of ethanol given intraperitoneally (i.p.) in a low-to-moderate dose range. This study was designed to test the hypothesis that patterns of neuronal activation across brain regions implicated in social activity and social preference (used as an index of low versus high anxiety-like social responding) would be affected by acute ethanol differently in adolescent females with high and low social preference, with initial levels of social preference also predicting ethanol-induced changes in social behavior. Adolescent female Fos-LacZ rats were given social interaction tests on postnatal day (P)33 for determination of baseline levels of responding to an unfamiliar social partner and on P35 following administration of 0 or 0.75 g/kg ethanol. Brain tissue was collected, and expression of β-galactoside (β-gal) was used as an index of neuronal activation. Baseline levels of social preference did not predict social responsiveness to an acute ethanol challenge, whereas significant decreases in this social measure that reflects anxiety-like behavioral alterations were evident in adolescent females challenged with ethanol relative to saline-injected controls, suggesting high sensitivity to the anxiogenic effects of ethanol. Ethanol precipitated negative relationships between social preference and prefrontal cortical activation, decreased neuronal activation of the anterior cingulate cortex, but substantially increased β-gal expression in the central amygdala. These results suggest high sensitivity of the prefrontal cortical regions and central amygdala to ethanol-induced alterations in adolescent Fos-LacZ females and provide a background for further phenotyping of neurons activated by ethanol under social test circumstances.

Methods for Exploring the Circuit Basis of Ethanol-Induced Changes in Drosophila Group Locomotor Activity.

Locomotion is a behavioral readout that can be used to understand responses to specific stimuli or perturbations. The fly Group Activity Monitor (flyGrAM) provides a high-throughput and high-content readout of the acute stimulatory and sedative effects of ethanol. The flyGrAM system is adaptable and seamlessly introduces thermogenetic or optogenetic stimulation to dissect neural circuits underlying behavior and tests responses to other volatilized stimuli (humidified air, odorants, anesthetics, vaporized drugs of abuse, etc.). The automated quantification and readout of activity provide users with a real-time representation of the group activity within each chamber throughout the experiment, helping users to quickly determine proper ethanol doses and duration, run behavioral screens, and plan follow-up experiments.

Changes in serotonin neurotransmission as assayed by microdialysis after acute, intermittent or chronic ethanol administration and withdrawal.

The serotonergic neurotransmitter system is involved in many ethanol-induced changes, including many behavioural alterations, as well as contributing to alcohol dependence and its withdrawal. This review has evaluated microdialysis studies where alterations in the serotonin system, that is, serotonin, 5-HT, or its metabolite 5-hydroxyindoleacetic acid, 5-HIAA, have been reported during different ethanol intoxication states, as well as in animals showing alcohol preference or not. Changes in 5-HT receptors and the 5-HT transporter are briefly reviewed to comprehend the significance of changes in microdialysate 5-HT concentrations. Changes in 5-HT content following acute, chronic and during ethanol withdrawal states are evaluated. In addition, the serotoninergic system was assessed in animals that have been genetically selected for alcohol preference to ascertain whether changes in this monoamine microdialysate content may contribute to alcohol preference. Changes occurred in 5-HT signalling in the limbic brain regions, increasing after acute ethanol administration in specific brain regions, particularly at higher doses, while chronic alcohol exposure essentially decreased serotonergic transmission. Such changes may play a pivotal role in emotion-driven craving and relapse. Depending on the dosage, mode of administration and consumption rate, ethanol affects specific brain regions in different ways, enhancing or reducing 5-HT microdialysate content, thereby inducing behavioural and cognitive functions and enhancing ethanol consumption. Microdialysis studies demonstrated that ethanol induces several alterations in 5-HT content as well as its metabolites, 5-HIAA and 5-HTOL, not only in its release from a specific brain region but also in the modifications of its different receptor subtypes and its transporter.

Astrocytic Responses to Binge Alcohol Intake in the Mouse Hindbrain.

Ethanol is the most commonly used toxic chemical in human cultures. Ethanol predominantly damages the brain causing various neurological disorders. Astrocytes are important cellular targets of ethanol in the brain and are involved in alcoholic symptoms. Recent studies have revealed the diversity of astrocyte populations in the brain. However, it is unclear how the different astrocyte populations respond to an excess of ethanol. Here we examined the effect of binge ethanol levels on astrocytes in the mouse brainstem and cerebellum. Ethanol administration for four consecutive days increased the glial fibrillary acidic protein (GFAP)-immunoreactive signals in the spinal tract of the trigeminal nerve (stTN) and reticular nucleus (RN). Another astrocyte marker, aquaporin 4 (AQP4), was also increased in the stTN with a pattern similar to that of GFAP. However, in the RN, the immunoreactive signals of AQP4 were different from that of GFAP and were not changed by ethanol administration. In the cerebellum, GFAP-positive signals were found in all four astrocytic populations, and those in the Bergmann glia were selectively eliminated by ethanol administration. We next examined the effect of estradiol on the ethanol-induced changes in astrocytic immunoreactive signals. The administration of estradiol alone increased the AQP4-immunoreactivity in the stTN with a pattern similar to that of ethanol, whereas the co-administration of estradiol and ethanol suppressed the intensity of the AQP4-positive signals. Thus, binge levels of ethanol intake selectively affect astrocyte populations in the brainstem and cerebellum. Sex hormones can affect the ethanol-induced neurotoxicity via modulation of astrocyte reactivity.