Abstract: Objective：To investigate the effects of estrogen replacement on the expression of silent information regulator 1（SIRT1） in those ovariectomized rats, so as to explore the anti-aging effect of estrogen. Methods：Thirty-three female Sprague-Dawley（SD） rats aged three months were used to develop the models by bilateral ovariectomy, which partly imitated the pathophysiological characteristics of menopause. There were three groups as follows: the treatment group（n=11） was treated with estradiol once a day for 12 weeks by intragastric administration in those ovariectomized rates; the sham-operated group（Sham，n=11） and the ovariectomized group（OVX，n=11） were treated with saline as controls. The levels of serum FSH and estradiol E2 was detected after 12 weeks′ treatment. The expressions of SIRT1 mRNA and protein in heart，liver and brain were analyzed by reverse transcriptional polymerase chain reaction（RT-PCR） and enzyme-linked immunosorbent assay（ELISA）. Results：After 12 weeks intragastric administration in rats，the level of FSH in the OVX group was significantly increased compared with the treatment group and the OVX group（P＜0.001），while the level of E2 was significantly decreased（P＜0.001）. In the heart，liver and brain tissues，the expression of SIRT1 protein and mRNA in the treatment group and the sham group were significantly higher than that in the OVX group（P＜0.05），while there was not significantly difference between the treatment group and the sham group（P＞0.05）. In the treatment group and the sham group，the expression of SIRT1 protein in the heart tissue was significantly higher than that in the liver and brain tissues（P＜0.05），while the expression of SIRT1 protein in the liver tissue was significantly higher than that in the brain tissue（P＜0.05）. However，the level of SIRT1 protein in the heart and liver tissues were higher than that in the brain tissues in the OVX group（P＜0.05），while there was not significantly differences in the liver and brain tissues（P＞0.05）. In the three groups，the level of SIRT1 mRNA in the heart and brain tissues were lower than that in the liver tissue（P＜0.05）. Conclusions：Estrogen can significantly increase the expressions of SIRT1 protein and mRNA in the ovariectomized rats, suggesting its potential effect of anti-aging.

Key words: Estrogens, Sirtuins, Climacteric, Aging