Protective effect of green tea extract against proline-induced oxidative damage in the rat kidney

We investigated, in vivo (acute and chronic), the effects of proline on thiobarbituric acid-reactive substances (TBA-RS) and on the activities of antioxidant enzymes such as catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in renal tissues (cortex and medulla) of rats. For acute administration, 29-day-old rats received a single subcutaneous injection of proline (18.2μmol/g body weight) or an equivalent volume of 0.9% saline solution and were sacrificed 1h later. For chronic treatment, proline was injected subcutaneously in the rats twice a day from the 6th to the 28th day of age, and the animals were killed 12h after the last injection. The results showed that acute administration of proline enhanced CAT, SOD and GSH-Px activities, as well as, TBARS in the cortex and decreased CAT activity in the medulla, while chronic treatment increased the activities of SOD in the cortex and increased CAT, SOD and GSH-Px in the medulla of rats. Furthermore, the green tea extract treatment for one week or from the 6th to the 28th day of age prevented the alterations caused by acute and chronic, respectively, proline administration. Herein, we demonstrated that proline alters antioxidant defenses and induces lipid peroxidation in the kidney of rats and the green tea extract was capable to counteract the proline-induced alterations.