Ethanol Neurotoxicity Research Articles

Neuroprotective Effect of Sterculia setigera Leaves Hydroethanolic Extract.

Plants are a valuable source of information for pharmacological research and new drug discovery. The present study aimed to evaluate the neuroprotective potential of the leaves of the medicinal plant Sterculia setigera. In vitro, the effect of Sterculia setigera leaves dry hydroethanolic extract (SSE) was tested on cultured cerebellar granule neurons (CGN) survival when exposed to hydrogen peroxide (H2O2) or 6-hydroxydopamine (6-OHDA), using the viability probe fluorescein diacetate (FDA), a lactate dehydrogenase (LDH) activity assay, an immunocytochemical staining against Gap 43, and the quantification of the expression of genes involved in apoptosis, necrosis, or oxidative stress. In vivo, the effect of intraperitoneal (ip) injection of SSE was assessed on the developing brain of 8-day-old Wistar rats exposed to ethanol neurotoxicity by measuring caspase-3 activity on cerebellum homogenates, the expression of some genes in tissue extracts, the thickness of cerebellar cortical layers and motor coordination. In vitro, SSE protected CGN against H2O2 and 6-OHDA-induced cell death at a dose of 10µg/mL, inhibited the expression of genes Casp3 and Bad, and upregulated the expression of Cat and Gpx7. In vivo, SSE significantly blocked the deleterious effect of ethanol by reducing the activity of caspase-3, inhibiting the expression of Bax and Tp53, preventing the reduction of the thickness of the internal granule cell layer of the cerebellar cortex, and restoring motor functions. Sterculia setigera exerts neuroactive functions as claimed by traditional medicine and should be a good candidate for the development of a neuroprotective treatment against neurodegenerative diseases.

Differential Early Mechanistic Frontal Lobe Responses to Choline Chloride and Soy Isoflavones in an Experimental Model of Fetal Alcohol Spectrum Disorder.

Fetal alcohol spectrum disorder (FASD) is the most common preventable cause of neurodevelopmental defects, and white matter is a major target of ethanol neurotoxicity. Therapeutic interventions with choline or dietary soy could potentially supplement public health preventive measures. However, since soy contains abundant choline, it would be important to know if its benefits are mediated by choline or isoflavones. We compared early mechanistic responses to choline and the Daidzein+Genistein (D+G) soy isoflavones in an FASD model using frontal lobe tissue to assess oligodendrocyte function and Akt-mTOR signaling. Long Evans rat pups were binge administered 2 g/Kg of ethanol or saline (control) on postnatal days P3 and P5. P7 frontal lobe slice cultures were treated with vehicle (Veh), Choline chloride (Chol; 75 µM), or D+G (1 µM each) for 72 h without further ethanol exposures. The expression levels of myelin oligodendrocyte proteins and stress-related molecules were measured by duplex enzyme-linked immunosorbent assays (ELISAs), and mTOR signaling proteins and phosphoproteins were assessed using 11-plex magnetic bead-based ELISAs. Ethanol's main short-term effects in Veh-treated cultures were to increase GFAP and relative PTEN phosphorylation and reduce Akt phosphorylation. Chol and D+G significantly modulated the expression of oligodendrocyte myelin proteins and mediators of insulin/IGF-1-Akt-mTOR signaling in both control and ethanol-exposed cultures. In general, the responses were more robust with D+G; the main exception was that RPS6 phosphorylation was significantly increased by Chol and not D+G. The findings suggest that dietary soy, with the benefits of providing complete nutrition together with Choline, could be used to help optimize neurodevelopment in humans at risk for FASD.

Evaluating signs of hippocampal neurotoxicity induced by a revisited paradigm of voluntary ethanol consumption in adult male and female Sprague-Dawley rats

BackgroundBinge alcohol drinking is considered a prominent risk factor for the development of alcohol-use disorders, and could be model in rodents through the standard two-bottle preference choice test. The goal was to recreate an intermittent use of alcohol during 3 consecutive days each week to ascertain its potential impact on hippocampal neurotoxicity (neurogenesis and other neuroplasticity markers), and including sex as a biological variable, given the well-known sex differences in alcohol consumption.MethodsEthanol access was granted to adult Sprague–Dawley rats for 3 consecutive days per week, followed by 4 days of withdrawal, during 6 weeks, mimicking the most common pattern of intake in people, drinking over the weekends in an intensive manner. Hippocampal samples were collected to evaluate signs of neurotoxicity.ResultsFemale rats consumed significantly more ethanol than males, although intake did not escalate over time. Ethanol preference levels remained below 40% over time and did not differ between sexes. Moderate signs of ethanol neurotoxicity were observed in hippocampus at the level of decreased neuronal progenitors (NeuroD + cells), and these effects were independent of sex. No other signs of neurotoxicity were induced by ethanol voluntary consumption when measured through several key cell fate markers (i.e., FADD, Cyt c, Cdk5, NF-L) by western blot analysis.ConclusionsOverall, the present results suggest that even though we modeled a situation where no escalation in ethanol intake occurred across time, mild signs of neurotoxicity emerged, suggesting that even the use of ethanol during adulthood in a recreational way could lead to certain brain harm.

Blood Vessels as a Key Mediator for Ethanol Toxicity: Implication for Neuronal Damage.

Excessive intake of ethanol is associated with severe brain dysfunction, and the subsequent neurological and behavioral abnormalities are well-established social risks. Many research studies have addressed how ethanol induces neurological toxicity. However, the underlying mechanisms with which ethanol induces neurological toxicity are still obscure, perhaps due to the variety and complexity of these mechanisms. Epithelial cells are in direct contact with blood and can thus mediate ethanol neurotoxicity. Ethanol activates the endothelial cells of blood vessels, as well as lymphatic vessels, in a concentration-dependent manner. Among various signaling mediators, nitric oxide plays important roles in response to ethanol. Endothelial and inducible nitric oxide synthases (eNOS and iNOS) are upregulated and activated by ethanol and enhance neuroinflammation. On the other hand, angiogenesis and blood vessel remodeling are both affected by ethanol intake, altering blood supply and releasing angiocrine factors to regulate neuronal functions. Thus, ethanol directly acts on endothelial cells, yet the molecular target(s) on endothelial cells remain unknown. Previous studies on neurons and glial cells have validated the potential contribution of membrane lipids and some specific proteins as ethanol targets, which may also be the case in endothelial cells. Future studies, based on current knowledge, will allow for a greater understanding of the contribution and underlying mechanisms of endothelial cells in ethanol-induced neurological toxicity, protecting neurological health against ethanol toxicity.

English

Alcohol consumption is a common well-known source of brain damages. This work aimed to evaluate the neuroprotective effect of Conyza aegyptiaca against ethanol-induced neurodegeneration in a Wistar rat binge drinking model. Animals, pretreated orally once a day during 3 days with the hydroethanolic extract of C. aegyptiaca (HECA 250 and 500 mg/kg), received daily intraperitoneally 7 g/kg of ethanol for 3 more days, concomitantly with HECA. Behavioral studies, brains tissue oxidative stress markers (MDA, GSH) assays, blood cell count and biochemistry analysis were performed. In vitro antioxidant activity using DPPH and FRAP tests and phytochemical tests were also realized. The negative geotaxis test showed that HECA 500 rats took significantly less time (3.24 ± 0.49 s, P<0.05 vs Ethanol control) compared to their congeners of Ethanol control group (6.80 ± 1.267 s, P<0.01 vs Sham). HECA treatment lowered significantly MDA levels (P<0.05 vs Ethanol control) and significantly increased GSH levels (P<0.05 vs Ethanol control). HECA treatment also significantly reduced the platelet count (P<0.001 vs Ethanol control). Ethanol 7 g/kg i.p raised hepatic function markers ALT and AST (respectively +27%, P<0.01 and +58.29%, P<0.01 vs Sham), effects significantly reversed by HECA treatments. DPPH scavenging activity with an IC50 of 368.769 ± 16.467 µg/mL and ferric ion reducing power with an EC50 of 139.65 ± 7.14 µg/mL should be related to the polyphenolic compounds found in HECA, tannins and flavonoids in particular. C. aegyptiaca could therefore potentially protect the brain against situations of neurodegeneration such as those observed in acute ethanol neurotoxicity. Key words: Conyza aegyptiaca, ethanol, brain, antioxidant, neuroprotection, neurodegeneration.

Alcohol-Induced Oxidative Stress and the Role of Antioxidants in Alcohol Use Disorder: A Systematic Review.

Alcohol use disorder (AUD) is a highly prevalent, comorbid, and disabling disorder. The underlying mechanism of ethanol neurotoxicity and the involvement of oxidative stress is still not fully elucidated. However, ethanol metabolism has been associated with increased oxidative stress through alcohol dehydrogenase, the microsomal ethanol oxidation system, and catalase metabolic pathways. We searched the PubMed and genome-wide association studies (GWAS) catalog databases to review the literature systematically and summarized the findings focusing on AUD and alcohol abstinence in relation to oxidative stress. In addition, we reviewed the ClinicalTrials.gov resource of the US National Library of Medicine to identify all ongoing and completed clinical trials that include therapeutic interventions based on antioxidants. The retrieved clinical and preclinical studies show that oxidative stress impacts AUD through genetics, alcohol metabolism, inflammation, and neurodegeneration.

Neuroprotective Effects of Crocin Against Ethanol Neurotoxicity in the Animal Model of Fetal Alcohol Spectrum Disorders.

Several experimental and clinical findings suggest that ethanol consumption during pregnancy activates an oxidative-inflammatory cascade followed by wide apoptotic neurodegeneration within several brain areas, including the hippocampus. Crocin can protect neurons because of its antioxidant, anti-inflammatory, and antiapoptotic effects. This study evaluated the crocin protective impact on ethanol-related neuroinflammation and neuronal apoptosis in the hippocampus of rat pups exposed to alcohol over postnatal days. Ethanol (5.25g/kg) was administrated in milk solution (27.8ml/kg) by intragastric intubation 2-10days after birth. The animals received crocin (15, 30, and 45mg/kg) 2-10days after birth. The hippocampus-dependent memory and spatial learning were evaluated 36days after birth using the Morris water maze task. Further, the concentrations of TNF-α and antioxidant enzymes were determined using ELISA assay to examine the antioxidant and anti-inflammatory activities. Also, immunohistochemical staining was performed to evaluate the glial fibrillary acidic protein (GFAP), Ionized calcium binding adaptor molecule 1(Iba-1), and caspase-3 expression. The administration of crocin significantly attenuated spatial memory impairment (P < 0.01) after ethanol neurotoxicity. Also, crocin led to a significant enhancement in SOD (P < 0.05) and GSH-PX (P < 0.01), whereas it caused a reduction in the TNF-α and MDA concentrations compared to the ethanol group (P < 0.01). Moreover, the hippocampal level of caspase-3 (P < 0.01) and the number of GFAPand Iba-1-positive cells decreased in the crocin group (P < 0.001). Crocin suppresses apoptotic signaling mediated by the oxidative-inflammatory cascade in rat pups exposed to ethanol after birth.

1H-[13C]-NMR investigation of brain energy metabolism in zebrafish: Impact of acute ethanol

Zebrafish has emerged as an excellent model organism for understanding the biology of the central nervous system. There is limited data pertaining to neurotransmitter energetics in the zebrafish brain. The present study evaluated brain energy metabolism in zebrafish by 1H-[13C]-NMR spectroscopy together with an intracardial administration of [1,6-13C2]glucose. Additionally, the impact of acute ethanol (1% in water) on brain energy metabolism was evaluated. The 13C turnover of brain amino acids from [1,6-13C2]glucose was measured in 1H-[13C]-NMR spectrum of brain tissue extract from 15 min to 90 min. The concentrations of neurometabolites in zebrafish are different than in rats and mice. There is fast incorporation of 13C labels into brain amino acids suggesting rapid glucose metabolism in the zebrafish brain. The incorporation of 13C in [4-13C]glutamate increased linearly until 30 min, and was maintained to a similar level thereafter. This is followed by [4-13C]glutamine and [3-13C]glutamate. The 13C turnover of [2–13C]GABA was much slower, and could attain ∼64% of [4-13C]glutamate labeling even at 90 min. Acute ethanol exposure significantly (p < 0.04) reduced levels of glutamate and NAA in the zebrafish brain. Most interestingly, the amount of 13C label accumulated into [4-13C]glutamate (p = 0.016), [2-13C]GABA (p = 0.016) and [3-13C]glutamate (p = 0.029) was decreased following acute neurotoxicity of ethanol. Moreover, the reduction in [4-13C]glutamine labeling in ethanol exposed fish points towards reduced synaptic transmission in acute ethanol exposed zebrafish. These data suggest that acute ethanol exposure in zebrafish suppresses neurometabolic activity of glutamatergic and GABAergic neurons. Zebrafish exhibited neurometabolism similar to rats, mice and humans, and could be used as an alternate model to study the mechanism of various neurological disorders, and drug screening.

Riboceine Regimen Attenuates Ethanol-induced Neuronal Damage in the Cerebellum of Adult Male Wistar Rats

Background: Although ethanol exerts its neurotoxic effect on the brain through inflammatory and oxidative processes, the effect of Riboceine on the brain following ethanol neurotoxicity is yet to be elucidated. Therefore, this study was designed to evaluate the effects of riboceine on the cellular, behavioral, and molecular impairments induced by ethanol toxicity in rats. Methods: A total of 24 male Wistar rats weighing between 160-170 grams were used for the study, and were divided into four groups of six rats each. After completion of the administration of ethanol and riboceine, and testing for motor impairment, the rats were sacrificed. The cerebellum was excised and processed for oxidative stress analyses, based on oxidative stress markers and histological examinations. The immunohistochemical expression of astrocytes in the cerebellum was examined, using Glial Fibrillary Acidic Protein (GFAP) stain. Results: This study demonstrated that ethanol-induced neurotoxicity in the cerebellum, characterized by increased oxidative stress profile, astrocyte activation, and neuronal death in the cerebellum, especially the Purkinje layer. Necrosis, significant decrease in Superoxide Dismutase (SOD), Catalase (CAT) and Gluathione (GSH) activities (P&lt;0.05) as well as astrogliosis was associated with ethanol treatment. However, riboceine was observed to significantly increase the cerebellar SOD, CAT and GSH activities with significantly reduced Malondialdehyde (MDA) levels (P&lt;0.05). It also attenuated the histomorphological alteration of the cerebellum and reduced the cerebellar astrocytes activation following ethanol-induced neurotoxicity, thus leading to the attenuation of motor impairment. Conclusion: Riboceine attenuated motor impairment caused by chronic ethanol-induced neurotoxicity, suggestive of its anti-oxidative and anti-inflammatory properties.

Role of MAPK ERK1/2 and p38 in the Regulation of Secretory Functions of Different Populations of Neuroglia in Ethanol-Induced Neurodegeneration.

We studied the participation of ERK1/2 and p38 in secretion of neurotrophic growth factors by various types of neuroglia under conditions of in vitro and in vivo modeled ethanol-induced neurodegeneration. The inhibitory role of these protein kinases in the production of neurotrophins by intact astrocytes and the absence of their participation in the regulation of functions of oligodendrocytes and microglial cells were shown. Under conditions of ethanol neurotoxicity, the role of ERK1/2 and p38 in the production of growth factors by glial elements was significantly changed. Neurodegeneration modeled in vitro led to inversion of the role of both protein kinases in the secretion of neurotrophins by astroglia and inhibition of the cytokine-synthesizing function of oligodendrocytes and microglial cells by ERK1/2 and p38. In mice receiving ethanol per os for a long time (as well as in cells in vitro exposed to ethanol), mitogen-activated kinases stimulated the function of astrocytes and inhibited the production of growth factors by microglial cells. At the same time, chronic alcoholization was accompanied by the appearance of the stimulating role of ERK1/2 and p38 in the implementation of the secretory function by oligodendrocytes.

Long-term protective effect of PACAP in a fetal alcohol syndrome (FAS) model

Prenatal ethanol exposure provokes teratogenic effects, due to oxidative stress and massive neuronal apoptosis in the developing brain that result in lifelong behavioral abnormalities. PACAP exerts anti-oxidative and neuroprotective activities on neuronal cells, and prevents ethanol neurotoxicity. The present study focused on the ability of PACAP to protect the brain of 30-day-old mice (P30) from prenatal alcohol exposure induced oxidative damage and toxicity. Pregnant mice were divided randomly into 4 groups, i.e. control group, ethanol group (1.5 g/kg ip daily injection), PACAP group (5 μg intrauterine daily injection) and an ethanol plus PACAP group. Offspring prenatally exposed to ethanol had decreased body weight and reduced cell survival. Moreover, production of ROS was sharply enhanced in the brain of prenatal ethanol-exposed animals, associated with an elevation in the activity of the antioxidant enzymes, and an increase of oxidative damages as shown by the accumulation of the lipid oxidation marker malondialdehyde and of protein carbonyl compounds. Intrauterine administration of PACAP during the gestational period restored the endogenous antioxidant system, prevented ROS overproduction and promoted the survival of dissociated cells from animals prenatally exposed to ethanol. Behavioral tests revealed that P30 animals exposed to ethanol during the prenatal period exhibited reduced motor activity, altered exploratory interest and increased anxiety. However, PACAP treatment significantly attenuated these behavioral impairments. This study demonstrates that PACAP exerts a potent neuroprotective effect against alcohol toxicity during brain development, and indicates that PACAP and/or PACAP analogs might be a useful tool for treatment of alcohol intoxication during pregnancy.

Apelin-13 attenuates spatial memory impairment by anti-oxidative, anti-apoptosis, and anti-inflammatory mechanism against ethanol neurotoxicity in the neonatal rat hippocampus

It has been shown that alcohol consumption by pregnant women can have detrimental effects on the developing fetus and lead to fetal alcohol spectrum disorders (FASD). Exposure to alcohol in rat pups during this period causes long-term changes in the structure of the animal's hippocampus, leading to impaired hippocampal-related brain functions such as navigation tasks and spatial memory. Apelin-13, a principal neuropeptide with inhibitory effects on neuroinflammation and brain oxidative stress production, has beneficial properties on memory impairment and neuronal injury. The protective effects of apelin-13 have been evaluated on ethanol-related neurotoxicity in the hippocampus of rat pups. Rat pups from 2 until 10 postnatal day, similar to the third trimester of pregnancy in humans, were intubated total daily dose of ethanol (5/27 g/kg/day). Immediately after intubation, 25 and 50 μg/ kg of apelin-13 was injected subcutaneously. By using Morris water maze task, the hippocampus- dependent memory and spatial learning were evaluated 36 days after birth. Then, Immunohistochemical staining was done to determine the levels of GFAP and caspase-3. ELISA assay was also performed to measure both TNF-α and antioxidant enzymes levels. The current study demonstrates that administration of apelin-13 attenuates spatial memory impairment significantly (P < 0.001). After ethanol neurotoxicity, apelin-13 could also increase the catalase level (P < 0.001), activity of total superoxide dismutase as well as glutathione concentration noticeably (P < 0.05). Other impacts of it could be mentioned as attenuating TNF-α production and also preventing lipid peroxidation (P < 0.001). In addition, the results showed that the level of GFAP as a neuroinflammation factor and the number of active caspase-3 positive cells can be decreased by apelin-13 (P < 0.01). Regarding the protective effects of apelin-13 against ethanol-induced neurotoxicity, it is a promising therapeutic choice for FASD; but more studies are needed.

Simvastatin attenuates spatial memory impairment via inhibiting microgliosis and apoptotic cell death against ethanol induced neurotoxicity in the developing rat hippocampus

Ethanol is associated with oxidative stress. Exposure to ethanol during childhood may lead to neurological disorders. Congenital disorders induced by alcohol are mainly caused by an oxidative-inflammatory cascade due to extensive apoptotic neurodegeneration in the brain, particularly in the hippocampus. Simvastatin, which acts as an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA), is widely used to manage cardiovascular diseases. Recently, the neuroprotective effects of simvastatin against nervous system disorders have been introduced. In this study, we examined the protective effects of simvastatin on ethanol-related neurotoxicity in the hippocampus of rat pups. Ethanol (5.27 g/kg) in a milk solution (27.8 mL/kg) was administered to male rat pups via intragastric intubation at 2–10 days after birth. Also, 10 and 20 mg/kg of simvastatin were injected to the animals. By using Morris water maze task, the hippocampus-dependent memory and spatial learning was evaluated 36 days after birth. An ELISA assay was performed to investigate the antioxidant and anti-inflammatory effects of simvastatin by measuring the levels of tumor necrosis factor-α (TNF-α), and antioxidant enzymes. To assess the expression levels of Iba1 immunohistochemical staining and caspase-3 immunofluorescence staining was performed. The current study demonstrated that administration of simvastatin significantly attenuates spatial memory impairment (P < 0.01) after ethanol neurotoxicity. Also simvastatin could considerably increase the total superoxide dismutaseand glutathione levels (P < 0.01). Moreover, it was associated with a greater reduction in malondialdehyde (P < 0.05) and TNF-α levels, compared to the ethanol group (P < 0.01). Furthermore, in the simvastatin group, the hippocampal level of caspase-3 and the level of Iba1-positive cells, reduced (P < 0.01).This study demonstrated that apoptotic signaling, mediated by the oxidative-inflammatory cascade, could be inhibited by simvastatin in rat pups with ethanol exposure in the postnatal period.

Inhibition of Ethanol Neurotoxicity by Treatment with Growth Factors and Estrogen

Ethanol ingestion by pregnant women is the primary cause of fetal alcohol syndrome, which is characterized by brain abnormalities and decreased mental capacity. In the present study,cultured neurons from embryonic rat cortices were used to study the effects of ethanol on cell survival and the potential for neuroprotection by certain growth factors and estrogen. Neurons were grown in the presence of a glial plane and in the absence of serum. Survival was assessed following chronic treatment with ethanol (45 mM) in the presence and absence of either nerve growth factor (NGF, 100ng/ml), basic fibroblast growth factor (bFGF, 5ng/ml), insulin-like growth factor I or II (IGF-I, IGF-II, both 10ng/ml), or estrogen (Es, 10nM) added on days one and four in vitro. On day in vitro 4 (DIV4) ethanol effects on neuronal viability were significantly prevented by NGF, bFGF, IGF-I, and Es. DIV6 survival of ethanol-treated neurons was increased significantly by treatment with NGF, bFGF, IGF-I, IGF-II, and Es. Nerve growth factor, bFGF, and IGF-I effects were shown to be dose-dependent. Administration of 1-100 ng/ml NGF, 0.05-5 ng/ml bFGF and 0.1-10ng/ml IGF-I led to statistically significant effects at 10, 5, and 1 ng/ml, respectively. Thus, ethanol’s effect on neuronal survival may be inhibited by simultaneous treatment with physiological doses of these factors.

Ethanol neurotoxicity is mediated by changes in expression, surface localization and functional properties of glutamate AMPA receptors.

Modifications in the subunit composition of AMPA receptors (AMPARs) have been linked to the transition from physiological to pathological conditions in a number of contexts, including EtOH-induced neurotoxicity. Previous work from our laboratory showed that EtOH withdrawal causes CA1 pyramidal cell death in organotypic hippocampal slices and changes in the expression of AMPARs. Here, we investigated whether changes in expression and function of AMPARs may be causal for EtOH-induced neurotoxicity. To this aim, we examined the subunit composition, localization and function of AMPARs in hippocampal slices exposed to EtOH by using western blotting, surface expression assay, confocal microscopy and electrophysiology. We found that EtOH withdrawal specifically increases GluA1 protein signal in total homogenates, but not in the post-synaptic density-enriched fraction. This is suggestive of overall increase and redistribution of AMPARs to the extrasynaptic compartment. At functional level, AMPA-induced calcium influx was unexpectedly reduced, whereas AMPA-induced current was enhanced in CA1 pyramidal neurons following EtOH withdrawal, suggesting that increased AMPAR expression may lead to cell death because of elevated excitability, and not for a direct contribution on calcium influx. Finally, the neurotoxicity caused by EtOH withdrawal was attenuated by the non-selective AMPAR antagonist 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide disodium salt as well as by the selective antagonist of GluA2-lacking AMPARs 1-naphthyl acetyl spermine. We conclude that EtOH neurotoxicity involves changes in expression, surface localization and functional properties of AMPARs, and propose GluA2-lacking AMPARs as amenable specific targets for the development of neuroprotective drugs in EtOH-withdrawal syndrome.

Assessment of Ethanol-Induced Toxicity on iPSC-Derived Human Neurons Using a Novel High-Throughput Mitochondrial Neuronal Health (MNH) Assay.

Excessive ethanol exposure can cause mitochondrial and cellular toxicity. In order to discover potential counteracting interventions, it is essential to develop assays capable of capturing the consequences of ethanol exposure in human neurons, and particularly dopaminergic neurons that are crucial for the development of alcohol use disorders (AUD). Here, we developed a novel high-throughput (HT) assay to quantify mitochondrial and neuronal toxicity in human dopaminergic neuron-containing cultures (DNs) from induced pluripotent stem cells (iPSCs). The assay, dubbed mitochondrial neuronal health (MNH) assay, combines live-cell measurement of mitochondrial membrane potential (MMP) with quantification of neuronal branching complexity post-fixation. Using the MNH assay, we demonstrated that chronic ethanol exposure in human iPSC-derived DNs decreases MMP and neuronal outgrowth in a dose-dependent manner. The toxic effect of ethanol on DNs was already detectable after 1 h of exposure, and occurred similarly in DNs derived from healthy individuals and from patients with AUD. We next used the MNH assay to carry out a proof-of-concept compound screening using FDA-approved drugs. We identified potential candidate compounds modulating acute ethanol toxicity in human DNs. We found that disulfiram and baclofen, which are used for AUD treatment, and lithium caused neurotoxicity also in the absence of ethanol, while the spasmolytic drug flavoxate positively influenced MNH. Altogether, we developed an HT assay to probe human MNH and used it to assess ethanol neurotoxicity and to identify modulating agents. The MNH assay represents an effective new tool for discovering modulators of MNH and toxicity in live human neurons.

Hydrogen sulfide improves spatial memory impairment via increases of BDNF expression and hippocampal neurogenesis following early postnatal alcohol exposure

According to experimental and clinical findings, fetal brain development may be interrupted by maternal alcohol consumption during pregnancy. Adult hippocampal neurogenesis is thought to play a role in cognition function (i.e. learning and memory). Recent evidence suggests that ethanol administration causes major apoptotic neurodegeneration in many regions of the rats’ developing brain during the synaptogenesis period. Based on the recent studies, H2S improve learning and memory via increased neurogenesis and antiapoptotic mechanisms in different animal models. In this study, we aimed to evaluate the protective effects of hydrogen sulfide on alcohol-induced memory impairment, hippocampus neurogenesis and neuronal apoptosis in rat pups with postnatal ethanol exposure.Administration of ethanol to male rat pups was performed through intragastric intubation on postnatal days 2–10. The pups were administered 1 mg/kg of NaHS (H2S donor) on postnatal days 2–10. For examining the spatial memory, Morris water maze test was carried out 36 days after birth. Following the behavioral test, immunohistochemical staining was performed to evaluate the expression levels of BrdU, BDNF and Apoptotic cell death was detected by TUNEL staining.Hydrogen sulfide (H2S) treatment could significantly improve spatial memory impairment (P < 0.05) and significantly increase the expression of BrdU and BDNF in dentate gyrus area (P < 0.05). It also decreased positive TUNEL cells, compared with the ethanol group (P < 0.01).Based on the findings, H2S makes significant neuroprotective effects on Ethanol neurotoxicity due to its neurogenesis and anti-apoptotic activity.

The Neurotoxicity of Ethanol and The Underlining Mechanisms

After ingestion, ethanol is mainly metabolized in the liver, eventually producing ATP and end products such as carbon dioxide and water. Because it is both water- and fat-soluble, it is easy to pass through the blood-brain barrier and affect the function of the nervous system. Overconsumption of alcohol or alcohol abuse is associated with various diseases including neurocognitive disorders. This article reviews the neurotoxicity of ethanol and discusses its possible molecular mechanisms.

Modulatory Effect of Decalepis hamiltonii on Ethanol-Induced Neurotoxicity in Drosophila melanogaster

Ethanol is known to be an effective inducer of oxidative stress in the brain tissues. Drosophila melanogaster is suitable in vivo model system to study neurotoxic effects of ethanol. The behavioral responses, levels of oxidative markers, and activity of antioxidant enzymes have been investigated in ethanol-exposed Drosophila flies. The results showed that acute ethanol exposure leads to hyperactivity of flies. If alcohol exposure is prolonged then sedation has occurred in the experimental flies. The latter was measured by sensitivity time (ST50) and recovery time (RC50). The levels of ROS and LPO (as cellular markers of oxidative stress) are significantly increased in ethanol-exposed flies while GSH level was declined. Furthermore, higher activities of catalase (CAT) and superoxide dismutase (SOD) were observed in the same group of flies. Ethanol neurotoxicity became more evident when a remarkable decrease of acetylcholine esterase (AChE) activity was seen in ethanol-exposed fruit flies. To battle ethanol neurotoxicity natural antioxidants would be the best choice. According to previously reported studies on the antioxidant capacity of Decalepis hamiltonii (Dh) root extract, its protecting effect in this toxicity model has been investigated. Surprisingly, Dh aqueous extract treatment has increased the time of ST50 and decreased the RC50 values of ethanol-exposed flies. Moreover, we demonstrated that Dh pre-treatment can diminish the ROS and LPO levels. Dh treatment results in augment of GSH level and activity of CAT and SOD enzymes. Antioxidant potential of Dh could restore AChE activity too. This is the first report on protective effects of Dh natural antioxidants in Drosophila melanogaster against oxidative stress induced by ethanol.

Nicotinamide Inhibits Ethanol-Induced Caspase-3 and PARP-1 Over-activation and Subsequent Neurodegeneration in the Developing Mouse Cerebellum.

Fetal alcohol spectrum disorder (FASD) is the principal preventable cause of mental retardation in the western countries resulting from alcohol exposure during pregnancy. Ethanol-induced massive neuronal cell death occurs mainly in immature neurons during the brain growth spurt period. The cerebellum is one of the brain areas that are most sensitive to ethanol neurotoxicity. Currently, there is no effective treatment that targets the causes of these disorders and efficient treatments to counteract or reverse FASD are desirable. In this study, we investigated the effects of nicotinamide on ethanol-induced neuronal cell death in the developing cerebellum. Subcutaneous administration of ethanol in postnatal 4-day-old mice induced an over-activation of caspase-3 and PARP-1 followed by a massive neurodegeneration in the developing cerebellum. Interestingly, treatment with nicotinamide, immediately or 2h after ethanol exposure, diminished caspase-3 and PARP-1 over-activation and reduced ethanol-induced neurodegeneration. Conversely, treatment with 3-aminobenzadine, a specific PARP-1 inhibitor, was able to completely block PARP-1 activation, but not caspase-3 activation or ethanol-induced neurodegeneration in the developing cerebellum. Our results showed that nicotinamide reduces ethanol-induced neuronal cell death and inhibits both caspase-3 and PARP-1 alcohol-induced activation in the developing cerebellum, suggesting that nicotinamide might be a promising and safe neuroprotective agent for treating FASD and other neurodegenerative disorders in the developing brain that shares similar cell death pathways.