Toxic effects of combined treatment of 1,2-dichloroethane and ethanol on mouse brain and the related mechanisms.

The aim of this study was to explore the mechanisms of brain damage induced by the combined treatment of mice with 1,2-dichloroethane (1,2-DCE) and ethanol. Mice were divided into control group; 1,2-DCE-intoxicated group; ethanol-treated group; and low-, medium-, and high-dose combined treatment groups. Histological observations along with brain organ coefficients and water content were used to measure the brain damage directly and indirectly. The levels of nonprotein sulfhydryls, malondialdehyde (MDA), and superoxide dismutase activity were used as parameters to evaluate oxidative stress in the brain. Protein and messenger RNA (mRNA) levels of cytochrome P450 2E1 (CYP2E1), zonula occludens-1 (occludin and zo-1), aquaporin-4 (AQP4), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase (HO)-1, and the γ-glutamyl cysteine synthetase catalytic and modulatory subunits (γ-GCSc, GR, and γ-GCSm) in the brain were examined by Western blot analysis and quantitative polymerase chain reaction analysis, respectively. Effects of the combined treatment of 1,2-DCE and ethanol were evaluated by analysis of variance with a factorial design. The results suggested that combined exposure to ethanol and 1,2-DCE synergistically increased CYP2E1 protein and mRNA levels, accelerated the metabolism of ethanol and 1,2-DCE in the brain tissue, induced high production of reactive oxygen species (ROS), and increased MDA levels, thereby damaging the blood-brain barrier and causing obvious pathological changes in brain tissue. However, the increased level of ROS activated the Nrf2 signal transduction pathway, promoting the expression of HO-1 and glutathione-related antioxidant enzymes in the brain to protect the cells from oxidative damage.

Positive allosteric modulators differentially affect full versus partial agonist activation of the glycine receptor.

Taurine acts as a partial agonist at the glycine receptor (GlyR) in some brain regions such as the hippocampus, striatum, and nucleus accumbens. Ethanol, volatile anesthetics, and inhaled drugs of abuse are all known positive allosteric modulators of GlyRs, but their effects on taurine-activated GlyRs remain poorly understood, especially their effects on the high concentrations of taurine likely to be found after synaptic release. Two-electrode voltage-clamp electrophysiology in Xenopus laevis oocytes was used to compare the enhancing effects of ethanol, anesthetics, and inhalants on human homomeric α1-GlyR activated by saturating concentrations of glycine versus taurine. Allosteric modulators had negligible effects on glycine-activated GlyR while potentiating taurine-activated currents. In addition, inhaled anesthetics markedly enhanced desensitization rates of taurine- but not glycine-activated receptors. Our findings suggest that ethanol, volatile anesthetics, and inhalants differentially affect the time courses of synaptic events at GlyR, depending on whether the receptor is activated by a full or partial agonist.

Effects of vigabatrin, an irreversible GABA transaminase inhibitor, on ethanol reinforcement and ethanol discriminative stimuli in mice.

We tested the hypothesis that the irreversible γ-amino butyric acid transaminase inhibitor, γ-vinyl γ-amino butyric acid [vigabatrin (VGB)], would reduce ethanol reinforcement and enhance the discriminative-stimulus effect of ethanol, effectively reducing ethanol intake. The present studies used adult C57BL/6J (B6) mice in well-established operant, two-bottle choice consumption, locomotor activity, and ethanol discrimination procedures to comprehensively examine the effects of VGB on ethanol-supported behaviors. VGB dose-dependently reduced operant responding for ethanol and ethanol consumption for long periods of time. Importantly, a low dose (200 mg/kg) of VGB was selective for reducing ethanol responding without altering the intake of food or water reinforcement. Higher VGB doses (>200mg/kg) reduced ethanol intake, but also significantly increased water consumption and, more modestly, increased food consumption. Although not affecting locomotor activity on its own, VGB interacted with ethanol to reduce the stimulatory effects of ethanol on locomotion. Finally, VGB (200 mg/kg) significantly enhanced the discriminative-stimulus effects of ethanol as evidenced by significant leftward and upward shifts in ethanol generalization curves. Interestingly, VGB treatment was associated with slight increases in blood ethanol concentrations. The reduction in ethanol intake by VGB appears to be related to the ability of VGB to potentiate the pharmacological effects of ethanol.

Cannabinoids enhance susceptibility of immature brain to ethanol neurotoxicity.

OBJECTIVE: Marijuana and alcohol are most widely abused drugs among women of reproductive age. Neurocognitive deficits have been reported in children whose mothers used marijuana during pregnancy. Maternal consumption of ethanol is known to cause serious developmental deficits METHODS: Infant rats and mice received systemic injections of Delta(9)-tetrahydrocannabinol (THC; 1-10mg/kg) or the synthetic cannabinoid WIN 55,212-2 (1-10mg/kg), alone or in combination with subtoxic and toxic ethanol doses, and apoptotic neurodegeneration was studied in the brains RESULTS: Acute administration of THC (1-10mg/kg), the principal psychoactive cannabinoid of marijuana, markedly enhanced proapoptotic properties of ethanol in the neonatal rat brain. THC did not induce neurodegeneration when administered alone. Neuronal degeneration became disseminated and severe when THC was combined with a mildly intoxicating ethanol dose (3gm/kg), with the effect of this drug combination resembling the massive apoptotic death observed when administering ethanol alone at much higher doses. The detrimental effect of THC was mimicked by the synthetic cannabinoid WIN 55,212-2 (1-10mg/kg) and counteracted by the CB(1) receptor antagonist SR141716A (0.4mg/kg). THC enhanced the proapoptotic effect of the GABA(A) agonist phenobarbital and the N-methyl-D-aspartate receptor antagonist dizocilpine. Interestingly, infant CB(1) receptor knock-out mice were less susceptible to the neurotoxic effect of ethanol. Furthermore, the CB(1) receptor antagonist SR141716A ameliorated neurotoxicity of ethanol INTERPRETATION: These observations indicate that CB(1) receptor activation modulates GABAergic and glutamatergic neurotransmission and primes the developing brain to suffer apoptotic neuronal death.

Dual orexin receptor antagonism by almorexant does not potentiate impairing effects of alcohol in humans.

The orexin system plays a pivotal role in the regulation of the sleep/wake state. Almorexant is a selective, orally available dual orexin receptor antagonist. This study evaluated the pharmacokinetic (PK) and pharmacodynamic (PD) interactions between almorexant (200 mg p.o.) and alcohol (0.6 g/L i.v. ethanol clamp for 5 h) using various cognitive and psychomotor performance tests in healthy subjects (n=20; 10 males and 10 females) in a 4-way crossover study. No effect of almorexant on ethanol PK was observed. The effects of ethanol on the PK of almorexant were limited, its exposure (AUC) increased by 21%; the median difference in tmax was 1.2 h; t1/2 and Cmax of almorexant were unchanged. Almorexant showed decreases in adaptive tracking performance, saccadic peak velocity, and subjective alertness as assessed by visual analog scale (VAS) of Bond and Lader, but had no or small effects on smooth pursuit eye movements, body sway, VAS for alcohol intoxication, and a memory test. Almorexant administered together with ethanol showed additive effects for adaptive tracking performance, saccadic peak velocity, subjective alertness and, possibly, calmness, but not on body sway, smooth pursuit, VAS for alcohol intoxication, or memory testing. To conclude, administration of almorexant together with ethanol was associated with additive effects for some of the measured cognitive and psychomotor performance tests. No indications of synergistic effects of almorexant and ethanol for any measured variable were observed.

Ethanol, Zn2+ and insulin interact as progression factors to enhance DNA synthesis synergistically in the presence of Ca2+ and other cell cycle initiators in fibroblasts.

In serum-starved NIH 3T3 fibroblasts, ethanol (30-80 mM) promoted the effects of insulin and insulin-like growth factor I (IGF-I) on DNA synthesis in a Zn(2+)-dependent manner. Ethanol and Zn(2+) were most effective when added shortly before or after insulin, indicating that all these agents facilitated cell cycle progression. The synergistic effects of ethanol, Zn(2+) and insulin (or IGF-I) on DNA synthesis required 1.1-2.3 mM Ca(2+), which seemed to act as the cell cycle initiator. When serum-starved cells were pretreated for 2 h with other cell cycle initiators such as 10% (v/v) serum, 50 ng/ml platelet-derived growth factor or 2 ng/ml fibroblast growth factor, subsequent co-treatments with 60 mM ethanol, Zn(2+) and insulin for an 18 h period again synergistically increased DNA synthesis. Of the various signal transducing events examined, ethanol stimulated cellular uptake of (45)Ca and it enhanced the stimulatory effects of insulin on p70 S6 kinase activity in a Zn(2+)-dependent manner. In contrast, ethanol inhibited insulin-induced activating phosphorylation of p42/p44 mitogen-activated protein kinases; these inhibitory ethanol effects were prevented by Zn(2+). The results show that, in NIH 3T3 fibroblasts, ethanol can promote cell cycle progression in the presence of a cell cycle initiator as well as Zn(2+) and insulin (or IGF-I).