Abstract: To study the protective effects of Oleanolic Acid on Testicular DNA Damage in natural aging rats,and to explore the possible mechanism.The 18-month old male SD rats were randomly divided into natural aging group,OA low and high dose group,with 10 rats in each group.Another 10 3-month old rats were used as young control group.OA low and high dose groups were given gastric gavage of OA 5 and 25 mg/kg,respectively,while the young control group and the natural aging group were given saline six times per week,lasting for 6 months.After fasting for 12 hours,the rats were sacrificed.Then,the testes were immediately removed and weighed.The change of testicular tissue morphology was observed by HE staining.The expression and localization of DNA damage-associated protein 53BP1 and ATR were observed by Immunohistochemistry.The relative expression levels of senescence associated protein p21 and DNA damage-related proteins γ-H2AX,Chk1 and p-p53 in testes were detected by Western Blot.HE showed that OA significantly improved the testicular tissue structure of natural aging rats.Compared with young control group,the levels of γ-H2AX protein in testis were significantly upregulated in natural aging group.However,the expression of γ-H2AX significantly decreased in OA-treated groups.In addition,the numbers of ATR-and 53BP1-positive cells,and the protein expression levels of p21,Chk1,and p-p53 were significantly upregulated in testis of rats in natural aging group when compared with young control group.As expected,OA significantly restored these changes.Taken together,OA protected against testicular DNA damage of natural aging rats,which may be associated with ATR/Chk1/P53 signaling.

Key words: Oleanolic acid, Aging, Testis, DNA damage