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 expose d to cigarette smoke for 90 d and simultaneously given 5,000 IU vitami n A/kg body weight. Lipid peroxidation products, scavenging enzymes an d free fatty acids were estimated in liver, lungs and heart. Cigarette smoke exposure increased the concentrations of malondialdehyde, conju gated dienes and hydroperoxides. The activities of superoxide dismutas e 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 supplementatio n to smoke-exposed rats produced increased resistance to lipid peroxid ation and increased the activities of scavenging enzymes, producing no rmal or higher enzyme activities. The activities of GSSG-Rase and GSSG -Pxase and the glutathione content reduced to normal levels. These res ults indicate that lipid peroxidation induced by cigarette smoke can b e protected against by vitamin A supplementation and their protection may be due to vitamin A's antioxidant activities.