Vitamin a Supplementation Induces Oxidative Stress and Decreases the Immunocontent of Catalase and Superoxide Dismutase in Rat Lungs

Lungs require an adequate supply of vitamin A for normal embryonic development, postnatal maturation, and maintenance and repair during adult life. However, recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer, although the mechanisms underlying this effect are still unknown. Here, the authors studied the effect of vitamin A supplementation on oxidative stress parameters in lungs of Wistar rats. Vitamin A supplementation either at therapeutic (1000 and 2500 IU/kg) or excessive (4500 and 9000 IU/kg) doses for 28 days induced lipid peroxidation, protein carbonylation, and oxidation of protein thiol groups, as well as change in catalase (EC 1.11.1.6; CAT) and superoxide dismutase (EC 1.15.1.1, SOD) activities and immunocontents. These results altogether suggest that vitamin A supplementation causes significant changes in redox balance the free radical status in lungs, which are frequently associated to severe lung dysfunction.