L-carnitine mediates protection against DNA damage in lymphocytes of aged rats.

It has been proposed that age-associated disorders are related to a time-dependent shift in the antioxidant/prooxidant balance towards oxidative damage. Increased production of oxidants in vivo can cause damage to intracellular macromolecules such as DNA, proteins and lipids, which can in turn lead to oxidative injury. Carnitine is a vitamin-like compound that serves as a carrier to transport long-chain fatty acids into the mitochondria for beta-oxidation. In the present study, the effect of L-carnitine, a widely recognized essential nutrient, was evaluated on the status of lipid peroxidation and certain antioxidant enzymes and DNA damage in lymphocytes with relation to age in male wistar rats. The levels of lipid peroxides were remarkably increased whereas, the activities of antioxidant enzymes were significantly decreased in aged control animals when compared to younger controls. In aged animals, administration of L-carnitine for 21 days significantly decreased the levels of lipid peroxides and improved the activities of antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. L-Carnitine enhanced T-cell proliferative responses as evaluated by T-cell proliferation assay using [3H] thymidine incorporation and also significantly reduced DNA damage, apoptosis and TNF-alpha level in lymphocytes of aged animals. Our results suggest that L -carnitine may have a vital role in improving functions in the cells of the immune system particularly the lymphocytes possibly through its antioxidant action.