目的 探究淫羊藿苷对自然衰老大鼠睾丸生殖细胞DNA损伤的保护作用及其分子机制。方法 将SPF级SD雄性大鼠随机分为4组，分别为青年对照组（2月龄）、衰老模型组（16月龄）和淫羊藿苷低、高剂量组（2、6 mg/kg，16月龄），每组8只，给予普通或含药饲料饲养4个月，禁食12 h后处死大鼠。HE染色法观察睾丸组织形态变化；黄嘌呤氧化酶法和硫代巴比妥酸法检测睾丸组织中超氧化物歧化酶（SOD）活力和丙二醛（MDA）水平；免疫荧光法检测睾丸组织中核因子E2相关因子2（Nrf2）及DNA损伤相关蛋白γ-H2AX的表达和定位；Western blotting法检测睾丸组织中Nrf2及其下游相关蛋白血红素氧合酶-1（HO-1）、醌氧化还原酶1（NQO1）、γ-H2AX和DNA损伤修复相关蛋白p-p53和p21表达水平。结果 HE染色结果表明，淫羊藿苷能明显改善自然衰老大鼠睾丸组织形态学变化，显著提高衰老大鼠睾丸组织SOD活力，降低MDA水平；免疫荧光结果显示，淫羊藿苷能明显上调衰老大鼠睾丸组织中各级生精细胞内Nrf2蛋白表达水平，明显下调初级精母细胞和精原细胞中γ-H2AX蛋白表达水平；Western blotting结果显示，淫羊藿苷能显著上调衰老大鼠睾丸组织中Nrf2、HO-1和NQO1蛋白表达水平，下调γ-H2AX、p-p53和p21蛋白表达水平。结论 淫羊藿苷可减轻自然衰老大鼠睾丸生殖细胞DNA损伤，其机制与激活Nrf2/HO-1信号通路有关。

Objective To study the protective effects of icariin on DNA damage of testicular germ cells in natural aging rats and explore the possible mechanism. Methods In the study, the SD rats were separated into four groups at random, with eight rats in each group:adult control group (2 months old), aging model group (16 months old), low and high doses of icariin-treated groups (2 mg/kg and 6 mg/kg, 16 months old). The adult control group and the aging model group were fed with normal diet for four months. Icariin-treated groups were given medicated feed for four months. After fasting for 12 h, all the rats were put to death. The testicular morphology was observed using HE staining. The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in testicular tissue were detected by xanthine oxidase method and thiobarbituric acid method, respectively. The protein expression of Nrf2 and γ-H2AX were detected by immunofluorescence. The relative protein expression levels of Nrf2, HO-1, NQO1, γ-H2AX, p-p53, and p21 were detected by Western blotting. Results HE staining results showed that icariin significantly improved the structure of testicular tissue of natural aging rats. Compared with the aging model group, icariin significantly increased the SOD activity and decreased the MDA content in testis. In addition, immunofluorescence results showed that icariin significantly decreased the expression of DNA damage response protein γ-H2AX and increased the protein expression of Nrf2 in testicular germ cells of aging rats. Moreover, Western blotting results showed that icariin significantly increased the relative protein expression levels of Nrf2, HO-1 and NQO1 in testis, when compared with aging model group. In parallel, the relative protein expression levels of γ-H2AX, p-p53, and p21 were significantly decreased. Conclusion Icariin attenuates DNA damage in testicular germ cells of natural aging rats, which may be associated with the activation of Nrf2/HO-1 signaling pathway.

R285.5

国家自然科学基金资助项目（81873077）；国家自然科学基金资助项目（81573931）；国家自然科学基金资助项目（81774316）；国家自然科学基金资助项目（81503334）