Effect of 4-methylpyrazole on antioxidant enzyme status and lipid peroxidation in the liver of rats after exposure to ethylene glycol and ethyl alcohol

Oxidative stress and biochemical indicators in blood of patients addicted to alcohol treated for acute ethylene glycol poisoning

Ethylene glycol (EG), in addition to its neurotoxic and nephrotoxic effects, evokes oxidative stress. The aim of this study was to assess the influence of the ethylene glycol on the biochemical indicators and oxidoreductive balance of patients treated for acute poisoning. The total study group consisted of 56 persons including 26 alcoholics who took EG as a substitute for ethyl alcohol in the course of alcohol dependence syndrome and 30 controls. Severity of poisoning, results of acid-base parameters, biochemical, and toxicological tests as well as biomarkers of the oxidative stress in blood were analyzed during the patients' hospitalization. The key issue was to assess the oxidative stress and biochemical disturbances caused by EG and the type of treatment applied in the course of poisoning. Significant changes in some parameters were found both at time of diagnosis and after treatment initiation (ethanol as an antidote and hemodialysis). The most important differences included the activity of hepatic parameters (aspartate aminotransferase, AST) and oxidative stress markers like catalase (CAT); correlation of the lipid peroxidation products level (TBARS) with urea concentration has been shown. On the last day of the hospitalization, in some cases, the mutual correlation between the evaluated markers were observed, for example, between alanine transaminase (ALT) and glutathione reductase (GR), and urea concentration and glutathione level (GSH/GSSG). The concentration of ions (H⁺) had a major impact on the oxidoreductive balance, correlating with the elevated GR and GSH/GSSG levels.

Alcohol consumption before pregnancy causes detrimental fetal development and maternal metabolic disorders

Alcohol consumption before or during pregnancy poses serious health risks to the fetus; however, the underlying mechanisms involved remain obscure. Here, we investigated whether ethanol consumption before pregnancy affects maternal or fetal health and whether pharmacological inhibition of CYP2E1, a major ethanol oxidation enzyme, by 4-methylpyrazole (4-MP) has therapeutic effects. We found that ethanol consumption (5%) 2 weeks before pregnancy resulted in a decrease in the number of viable fetuses and abnormal fetal development, and these effects were accompanied by impaired maternal glucose homeostasis and hepatic steatosis during pregnancy. Neonates of ethanol-fed mice had postnatal macrosomia and significantly decreased growth rates during the lactation period. However, treatment with 4-MP, a CYP2E1 inhibitor, markedly ameliorated the reduction in insulin action and glucose disposal responsiveness in the livers of ethanol-fed mice. Blockage of CYP2E1 significantly reduced the alteration in hepatic lipid deposition, fatty acid oxidation, mitochondrial energy status, and macrophage infiltration observed in ethanol-fed mice. Finally, there was a positive correlation between postnatal macrosomia or growth retardation and increased inflammatory responses. Collectively, our study suggests that even moderate ethanol intake may be detrimental to fetal development and may cause growth retardation through maternal metabolic disorders.

Effect of repeated administration of 4-methylpyrazole on renal function and lipid peroxidation products in rat kidney after ethylene glycol poisoning

Toxic effects of ethylene glycol (EG) and its metabolites are mainly related to metabolic acidosis and kidney damage. EG biotransformation involving CYP2E1 affects the oxidant-antioxidant balance. The study assessed the effect of repeated administration of 4-methylpyrazole (4MP, 15mg/kg b.w. after 2h, followed by 10mg/kg b.w. every 12h) on renal function (creatinine, urea and urinary protein levels) as well as products of kidney's lipid peroxidation (MDA and TBARS levels) in rats poisoned with EG (5745mg/kg b.w.). Serum EG and glycolic acid (GA) concentrations were measured throughout the experiment. Repeated administration of 4MP reduced the rate of EG elimination, extended the period of EG persistence in serum and significantly limited formation of GA. The study showed the temporary intensification of kidney oxidative processes that correlated with changes in kidney function. It was found that the use of 4MP in EG poisoning inhibited its biotransformation to toxic metabolites, but simultaneously intensified oxidative damages in kidneys.

Treatment with 4-methylpyrazole modulated stellate cells and natural killer cells and ameliorated liver fibrosis in mice

Background & Aims

Accumulating evidence suggests that retinol and its metabolites are closely associated with liver fibrogenesis. Recently, we demonstrated that genetic ablation of alcohol dehydrogenase 3 (ADH3), a retinol metabolizing gene that is expressed in hepatic stellate cells (HSCs) and natural killer (NK) cells, attenuated liver fibrosis in mice. In the current study, we investigated whether pharmacological ablation of ADH3 has therapeutic effects on experimentally induced liver fibrosis in mice.

Methods

Liver fibrosis was induced by intraperitoneal injections of carbon tetrachloride (CCl₄) or bile duct ligation (BDL) for two weeks. To inhibit ADH3-mediated retinol metabolism, 10 μg 4-methylpyrazole (4-MP)/g of body weight was administered to mice treated with CCl₄ or subjected to BDL. The mice were sacrificed at week 2 to evaluate the regression of liver fibrosis. Liver sections were stained for collagen and α-smooth muscle actin (α-SMA). In addition, HSCs and NK cells were isolated from control and treated mice livers for molecular and immunological studies.

Results

Treatment with 4-MP attenuated CCl₄- and BDL-induced liver fibrosis in mice, without any adverse effects. HSCs from 4-MP treated mice depicted decreased levels of retinoic acids and increased retinol content than HSCs from control mice. In addition, the expression of α-SMA, transforming growth factor-β1 (TGF-β1), and type I collagen α1 was significantly reduced in the HSCs of 4-MP treated mice compared to the HSCs from control mice. Furthermore, inhibition of retinol metabolism by 4-MP increased interferon-γ production in NK cells, resulting in increased apoptosis of activated HSCs.

Conclusions

Based on our data, we conclude that inhibition of retinol metabolism by 4-MP ameliorates liver fibrosis in mice through activation of NK cells and suppression of HSCs. Therefore, retinol and its metabolizing enzyme, ADH3, might be potential targets for therapeutic intervention of liver fibrosis.