Department of Zoology, Banaras Hindu University, Varanasi 221005, UP, India.
Steroids. 2012 May;77(6):609-20. doi: 10.1016/j.steroids.2012.02.004. Epub 2012 Feb 15.
The aim of present study was to investigate the changes in the testicular expression of aromatase, ER alpha, ER beta and iNOS protein and correlate these with serum testosterone and nitric oxide levels, to elucidate the role of estrogen and nitric oxide in the testis during aging. This study showed localization of aromatase and ER alpha mainly in the Leydig cell and showed close correlation of testicular aromatase level with circulating testosterone level suggesting that estrogen may be modulating testicular steroidogenesis. Localization ER alpha mainly in the mitotically active germ cell suggest possible role of estrogen in germ cell proliferation. This study showed basal level of nitric oxide during reproductively active period, whereas increased serum nitric oxide coincides with decreased testicular activity in old age. This study showed inverse correlation between aromatase and NO level. Treatment with either SNP or L-NAME on testicular steroidogenic factor (3-beta HSD/ StAR) or germ cell survival factor (Bcl2) showed that increased NO causes decreased steroidogenesis and increased germ cell apoptosis. In conclusion this study suggest that estrogen modulate steroidogenesis and germ cell survival in reproductively active period whereas in old age decreased estrogen concentration causes increased nitric oxide which in turn decreases testicular steroidogenesis and germ cell apoptosis.
本研究旨在探讨芳香化酶、ERα、ERβ 和 iNOS 蛋白在睾丸中的表达变化，并与血清睾酮和一氧化氮水平相关联，以阐明雌激素和一氧化氮在衰老过程中对睾丸的作用。本研究显示，芳香化酶和 ERα 主要定位于睾丸间质细胞（Leydig 细胞），并显示睾丸芳香化酶水平与循环睾酮水平密切相关，提示雌激素可能调节睾丸类固醇生成。ERα 主要定位于有丝分裂活跃的精原细胞，提示雌激素可能在精原细胞增殖中发挥作用。本研究显示，生殖活跃期一氧化氮水平基础水平较低，而老年时血清一氧化氮水平升高与睾丸活性降低相吻合。本研究显示，芳香化酶与 NO 水平呈负相关。用 SNP 或 L-NAME 处理睾丸类固醇生成因子（3-βHSD/StAR）或精原细胞存活因子（Bcl2）表明，NO 增加会导致类固醇生成减少和精原细胞凋亡增加。总之，本研究表明，雌激素在生殖活跃期调节类固醇生成和精原细胞存活，而在老年时，雌激素浓度降低导致一氧化氮增加，进而导致睾丸类固醇生成减少和精原细胞凋亡增加。
