Effect of vitamin A supplementation on cigarette smoke-induced lipid peroxidation.

The antioxidant activity of vitamin A against cigarette smoke-induced oxidative stress was investigated in rat tissues. The rats were exposed to cigarette smoke for 90 d and simultaneously given 5,000 IU vitamin A/kg body weight. Lipid peroxidation products, scavenging enzymes and free fatty acids were estimated in liver, lungs and heart. Cigarette smoke exposure increased the concentrations of malondialdehyde, conjugated dienes and hydroperoxides. The activities of superoxide dismutase and catalase were decreased, but glutathione content and glutathione peroxidase (GSSG-Pxase) activity were enhanced. Glutathione reductase (GSSG-Rase) activity was markedly inhibited. Vitamin A supplementation to smoke-exposed rats produced increased resistance to lipid peroxidation and increased the activities of scavenging enzymes, producing normal or higher enzyme activities. The activities of GSSG-Rase and GSSG-Pxase and the glutathione content reduced to normal levels. These results indicate that lipid peroxidation induced by cigarette smoke can be protected against by vitamin A supplementation and their protection may be due to vitamin A's antioxidant activities.