Protein Oxidation in Active and Abstinent Alcoholics in Comparison With Normal Controls

Abstract

Background-Though there is much evidence in support of the hypothesis that acute or chronic alcohol toxicity is mediated primarily via the generation of damaging free radical species, only very few studies had analysed the effect of alcohol withdrawal on protein oxidation and antioxidant status in alcoholics. Also studies concentrating on alcoholics without any clinical or biochemical evidence of liver disease and eliminating other confounders such as smoking are less. Hence the present study aimed to measure carbonyl protein as an index of oxidative damage to proteins in alcoholics without liver disease and determine whether it is reversible on abstinence from alcohol. Methods- The study was conducted in patients with alcohol dependence attending the de-addiction facility in a tertiary care hospital in south India. The study group comprised of 30 male alcoholics in the age group 20-60 years who exhibited no clinical or biochemical evidence of severe liver disease. Blood sample collection was done in the study group immediately after admission and after one month of reported abstinence from alcohol (Groups 1&2, n=30 each).The control group (Group 3, n=30) included healthy male subjects in the same age group as alcoholics with no or occasional alcohol consumption only. Serum Protein carbonyl (PC) levels and plasma Vitamin C levels were estimated in the study and control groups..The confounding effect of smoking on the parameters of oxidative stress was eliminated by appropriate statistical methods and estimated marginal means calculated. Results-PC levels were found to decrease significantly on abstinence from alcohol. Both active alcoholics and abstinent alcoholics show significantly elevated PC levels compared to controls even after eliminating the effect of smoking. Serum Vitamin C levels were found to be lower in both the alcoholic subgroups compared to non-alcoholic controls, but there was no significant elevation of levels on abstinence from alcohol. Conclusion-Oxidative damage to proteins is increased in alcoholics without liver disease which comes down on abstinence. Antioxidant supplementation may be essential during the withdrawal phase to reverse this damage.