Role of endogenous vitamin E in renal ischemic preconditioning process: differences between male and female rats

Antioxidants such as alpha-tocopherol [vitamin E] and beta-carotene [vitamin A] play an important role in protective effect of repeated brief periods of ischemia, namely ischemic preconditioning [IPC]. Values of these antioxidants were investigated and compared after induction of ischemia reperfusion [IR] and kidney IPC in both male and female rats. Forty eight Wistar rats were divided randomly into six groups of 8: groups A and B [male and female controls, respectively], group C [male IR or IR cases], group D [female IR cases] and groups E and F [male and female IPC cases, respectively]. In groups C and D, ischemia was induced by clamping of left renal arteries for 45 min. In groups E and F, rats underwent four cycles of 4 min of arterial clamping and 11 min of de-clamping before final 45 min ischemia induction. Afterward, serum was collected to assess the blood urea nitrogen, creatinine and vitamins E and A values. Renal tissues were obtained for histological assessments. alpha-tocopherol levels in male and female rats showed a significant increase in IPC compared with IR group [P<0.01] and also in female IPC compared with male IPC group. beta-carotene levels had no significant variations. Histological evaluation showed that IR-induced renal injuries were less in female rats. Also, protective effects of IPC were more in female rats [P<0.01]. Renal IPC reduced damages in both male and female rats, but tissue injuries in females were decreased much more along with the increase of endogenous vitamin E