Chronic Alcohol Exposure Induced Neuroapoptosis: Diminishing Effect of Ethyl Acetate Fraction from Aralia elata.

An ethyl acetate fraction from Aralia elata (AEEF) was investigated to confirm its neuronal cell protective effect on ethanol-induced cytotoxicity in MC-IXC cells and its ameliorating effect on neurodegeneration in chronic alcohol-induced mice. The neuroprotective effect was examined by methylthiazolyldiphenyl-tetrazolium bromide (MTT) and 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA) assays. As a result, AEEF reduced alcohol-induced cytotoxicity and oxidative stress. To evaluate the improvement of learning, memory ability, and spatial cognition, Y-maze, passive avoidance, and Morris water maze tests were conducted. The AEEF groups showed an alleviation of the decrease in cognitive function in alcohol-treated mice. Then, malondialdehyde (MDA) levels and the superoxide dismutase (SOD) content were measured to evaluate the antioxidant effect of AEEF in the brain tissue. Treatment with AEEF showed a considerable ameliorating effect on biomarkers such as SOD and MDA content in alcohol-induced mice. To assess the cerebral cholinergic system involved in neuronal signaling, acetylcholinesterase (AChE) activity and acetylcholine (ACh) content were measured. The AEEF groups showed increased ACh levels and decreased AChE activities. In addition, AEEF prevented alcohol-induced neuronal apoptosis via improvement of mitochondrial activity, including reactive oxygen species levels, mitochondrial membrane potential, and adenosine triphosphate content. AEEF inhibited apoptotic signals by regulating phosphorylated c-Jun N-terminal kinases (p-JNK), phosphorylated protein kinase B (p-Akt), Bcl-2-associated X protein (BAX), and phosphorylated Tau (p-Tau). Finally, the bioactive compounds of AEEF were identified as caffeoylquinic acid (CQA), 3,5-dicaffeoylquinic acid (3,5-diCQA), and chikusetsusaponin IVa using the UPLC-Q-TOF-MS system.

Impact of thiamine supplementation in the reversal of ethanol induced toxicity in rats.

One of the molecular mechanisms of alcohol induced toxicities is mediated by oxidative stress. Hence our studies were focused on the effect of thiamine (antioxidant) in the reversal of alcohol induced toxicity and comparison of the reversal with abstinence. Administration of ethanol at a dose of 4 g/kg body wt/day for 90 days to Sprague Dawley rats manifested chronic alcohol induced toxicity evidenced by decreased body weight, an increase in liver-body weight ratio, increase in activities of serum and liver aspartate transaminase (AST), alanine transaminase (ALT), gamma-glutamyl transpeptidase (GGT); decrease in the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase in the liver and brain. The levels of inflammatory markers, fibrosis markers and DNA fragmentation were also elevated in the serum, liver and brain. After ethanol administration for 90 days, the reversal of the alcohol induced toxicity was studied by supplementing thiamine at a dose of 25 mg/100 g body wt/day. Duration of the reversal study was 30 days. The activities of AST, ALT, GGT, scavenging enzymes as well as markers of inflammation and fibrosis in serum, liver and brain were reversed to a certain extent by thiamine. Changes in neurotransmitter levels in brain were also reversed by thiamine supplementation. DNA damage was decreased and DNA content increased in thiamine supplemented group compared to abstinence group showing a faster regeneration. In short, histopathological and biochemical evaluations indicate that thiamine supplemented abstinent rats made a faster recovery of hepatic and neuronal damage than in the abstinence group.

Dihydromyricetin as a novel anti-alcohol intoxication medication.

Alcohol use disorders (AUDs) constitute the most common form of substance abuse. The development of AUDs involves repeated alcohol use leading to tolerance, alcohol withdrawal syndrome, and physical and psychological dependence, with loss of ability to control excessive drinking. Currently there is no effective therapeutic agent for AUDs without major side effects. Dihydromyricetin (DHM; 1 mg/kg, i.p. injection), a flavonoid component of herbal medicines, counteracted acute alcohol (EtOH) intoxication, and also withdrawal signs in rats including tolerance, increased anxiety, and seizure susceptibility; DHM greatly reduced EtOH consumption in an intermittent voluntary EtOH intake paradigm in rats. GABA(A) receptors (GABA(A)Rs) are major targets of acute and chronic EtOH actions on the brain. At the cellular levels, DHM (1 µM) antagonized both acute EtOH-induced potentiation of GABA(A)Rs and EtOH exposure/withdrawal-induced GABA(A)R plasticity, including alterations in responsiveness of extrasynaptic and postsynaptic GABA(A)Rs to acute EtOH and, most importantly, increases in GABA(A)R α4 subunit expression in hippocampus and cultured neurons. DHM anti-alcohol effects on both behavior and CNS neurons were antagonized by flumazenil (10 mg/kg in vivo; 10 µM in vitro), the benzodiazepine (BZ) antagonist. DHM competitively inhibited BZ-site [(3)H]flunitrazepam binding (IC(50), 4.36 µM), suggesting DHM interaction with EtOH involves the BZ sites on GABA(A)Rs. In summary, we determined DHM anti-alcoholic effects on animal models and determined a major molecular target and cellular mechanism of DHM for counteracting alcohol intoxication and dependence. We demonstrated pharmacological properties of DHM consistent with those expected to underlie successful medical treatment of AUDs; therefore DHM is a therapeutic candidate.

Comparative study of the efficacy of ascorbic acid, quercetin, and thiamine for reversing ethanol-induced toxicity.

This study compares the curative effect of three antioxidants-ascorbic acid, quercetin, and thiamine-on ethanol-induced toxicity in rats. Administration of ethanol at a dose of 4 g/kg of body weight/day for 90 days initiated chronic alcohol-induced oxidative stress as shown by increased malondialdehyde level and DNA fragmentation in liver and brain. Ethanol administration also led to a decrease in DNA content. Activities of toxicity marker enzymes-alanine aminotransferase, aspartate aminotransferase, and γ-glutamyltranspeptidase-in liver and serum increased progressively upon ethanol administration. After ethanol administration for 90 days, the efficacy of antioxidant treatment of the alcohol-induced toxicity was studied by supplementing ascorbic acid (200 mg/100 g of body weight/day), quercetin (50 mg/kg of body weight/day), and thiamine (25 mg/kg of body weight/day) for 30 days. These groups were compared with the abstention group (not treated with ethanol). All the alterations induced by alcohol were reduced significantly by the supplementation of antioxidants and also with abstention. The regression by antioxidants was greater that of abstention. Antioxidants significantly reduced the oxidative stress induced by ethanol intoxication, increased membrane integrity, and also increased organ regeneration. Ascorbic acid was shown to be more effective than quercetin and thiamine in treating both hepatotoxicity and neurotoxicity induced by alcohol administration. This may be due to the higher antioxidant potential of ascorbic acid in physiological conditions.

Altered water-maze search behavior in adult guinea pigs following chronic prenatal ethanol exposure: lack of mitigation by postnatal fluoxetine treatment.

Ingestion of ethanol during pregnancy can result in teratogenic effects in humans, including significant and long-lasting neurobehavioral deficits. Similar results are seen in guinea pigs with chronic prenatal ethanol exposure (CPEE) via maternal ethanol administration, which produces deficits in Morris water-maze performance and impaired hippocampal functioning (e.g., decreased long-term potentiation, LTP). In this study, we tested whether postnatal treatment with fluoxetine, a selective serotonin reuptake inhibitor, decreases some of the neurobehavioral impairments produced by CPEE. Timed, pregnant guinea pigs received oral administration of ethanol (4g/kg maternal body weight) or isocaloric sucrose pair feeding (control) for 5 days/week throughout gestation. Offspring of the CPEE and control groups were randomly assigned to receive either fluoxetine (10mg/kg body weight/day) or saline intraperitoneally from postnatal day 10 to 48. Subsequent behavioral tests in the Morris water-maze revealed a significant increase in thigmotaxic swimming in CPEE offspring without apparent signs of impairment in spatial mapping of the hidden escape platform. Measures of hippocampal short- and long-term plasticity (paired-pulse facilitation, frequency facilitation, and LTP) were unaffected by CPEE, consistent with the behavioral data indicating normal hippocampal functioning. Postnatal fluoxetine administration resulted in a significant loss of body weight, but did not affect the increased thigmotaxic swimming following CPEE. These results indicate that changes in search strategies in the water-maze might be a highly sensitive index of CPEE-induced neurobehavioral toxicity that can occur in the absence of significant hippocampal dysfunction. Further, these data demonstrate that fluoxetine, at the selected treatment regime, does not mitigate the thigmotaxic swimming response to CPEE in the guinea pig.

Grape seed flavanols, but not Port wine, prevent ethanol-induced neuronal lipofuscin formation.

Lipofuscin is an end-product of lipid peroxidation which dramatically increases following ethanol consumption, as we have shown in hippocampal and cerebellar neurons. In this work, we corroborated observations indicating that supplementation of ethanol with 200 mg/l of grape seed flavanols prevents increased lipofuscin formation, an action that has been ascribed to the antioxidant properties of the flavanols. Because wine is an alcoholic beverage naturally rich in flavanols, we decided to study the effect of chronic ingestion of Port wine (PW), which also contains 20% ethanol and approximately 200 mg/l of flavanol oligomers, upon lipofuscin accumulation in the hippocampal CA1 and CA3 pyramidal neurons and in the cerebellar Purkinje cells. Six months old rats were fed with PW and results were compared with those obtained in ethanol-treated groups and pair-fed controls. After 6 months of treatment, the volume of lipofuscin per neuron was estimated using unbiased stereological methods. Treatment with PW resulted in an increase of lipofuscin in all neuronal populations studied when compared to controls and to rats treated with ethanol supplemented with flavanols. No differences were observed when comparisons were made with ethanol drinking rats. We conclude that PW, despite containing 20% ethanol and flavanols, does not prevent ethanol-induced lipofuscin formation as previously found in animals drinking ethanol plus flavanols. The reduced antioxidant capacity of PW might depend on the type and amount of flavanols present and on its content in sugars.

CPP and amlodipine alter the decrease in basal acetylcholine and choline release by audiogenic stimulus in hippocampus of ethanol-withdrawn rats in vivo.

Effects of N-methyl-D-aspartate (NMDA) receptor and Ca2+ channel antagonists on extracellular acetylcholine and choline release in the hippocampus of ethanol-withdrawn rats were investigated by in vivo microdialysis. Ethanol was administered to Wistar rats in a liquid diet for 28 days. Basal acetylcholine and choline levels significantly increased at the 24th hour of ethanol withdrawal syndrome (EWS). Either an NMDA receptor antagonist (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) or a calcium channel antagonist amlodipine was administered, and 15 min later, an audiogenic stimulus (100 dB, 1 min) was applied to rats. While audiogenic stimulus increased acetylcholine and had no effect on choline release in control rats, it decreased acetylcholine and increased choline release in ethanol-withdrawn rats. CPP (15 mg/kg) and amlodipine (20 mg/kg) reversed the decrement in acetylcholine and increment in choline release in EW rats. Their effects on acetylcholine and choline release were not different from saline in control rats. Therefore, our findings suggest that, (a) because of adaptive changes in EWS, decrease of the acetylcholine release following audiogenic stimulus may play a role in the triggering of seizures, (b) hippocampal glutamatergic pathway may play a role in the audiogenic stimulus induced decrement of acetylcholine release in EWS, (c) inhibition of this pathway by NMDA receptor and calcium channel antagonists may prevent triggering of the seizures.