ABSTRACT
Although it is well known that chronic ethanol abuse produces sexual dysfunction and impaired spermatogenesis, the mechanisms of ethanol-induced testicular alterations are not fully explained. Therefore, the aim of this study was to investigate the mechanisms of testicular oxidative damage in rats given drinking water containing 3% ethanol for 8 weeks. Control rats were pair-fed with saccharose. The mean daily ethanol intake was 4.05 g kg(-1), corresponding to the consumption of 41 of wine (10% alcohol) or 0.71 of whiskey (40% alcohol) by a man of 70 kg body wt. Exposure to ethanol caused a significant depletion in the testicular levels of glutathione (GSH), protein containing sulfhydryl groups, tocopherol and ascorbic acid, and an increase in the concentrations of malondialdehyde (index of lipid peroxidation) and carbonyl proteins (index of protein oxidation). Other effects were decreases in the concentration of adenosine 5'-triphosphate and in the activity of glutathione peroxidase, and an increase in the activity of alcohol dehydrogenase. In summary, this study shows that in the rat, daily consumption of ethanol in the drinking water increases lipid and protein oxidation. In addition to impaired antioxidant defence, an imbalance in energy production may also play a role in the toxic reaction to alcohol.
Subject(s)
Antioxidants/metabolism , Central Nervous System Depressants/pharmacology , Ethanol/pharmacology , Lipid Peroxidation/drug effects , Testis/drug effects , Adenosine Triphosphate/metabolism , Administration, Oral , Alcohol Dehydrogenase/metabolism , Animals , Ascorbic Acid/metabolism , Central Nervous System Depressants/toxicity , Ethanol/toxicity , Glutathione/drug effects , Glutathione/metabolism , Glutathione Peroxidase/metabolism , Male , Oxidation-Reduction/drug effects , Proteins/drug effects , Proteins/metabolism , Rats , Rats, Wistar , Testis/enzymology , Testis/metabolism , Vitamin E/metabolismABSTRACT
Oxidative modification of proteins is of great importance because of their biological role in transport, enzyme activity, immune response and membrane fluidity. This study investigated the redox status of proteins in plasma, erythrocyte and erythrocyte ghosts of chronic alcoholics; a comparison with subjects affected by chronic viral hepatitis and healthy controls was also performed. Compared to the other groups, chronic active alcoholics showed significant increase of plasma, erythrocyte and erythrocyte ghost concentrations of carbonyl proteins, marker of protein oxidative damage. Also, a significant correlation was noted between daily alcohol intake and plasma levels of carbonyl proteins. The incubation of fresh human plasma with acetaldehyde, but not with ethanol, led to a significant increase of the carbonyl protein production. In conclusion, plasma, erythrocyte and membrane proteins are oxidatively modified in active chronic alcoholics; these changes seem to be related to acetaldehyde rather than ethanol toxicity.
