Eeffect of soy isoflavones on serum sex hormones in aged female rats

Objective To observe the effect of soy isoflavones on main serum sex hormones and ovaries in aged female rats.Methods Fifty 20-month-old female rats were randomly divided into five groups:control group(with oral gavage of normal saline),low-,moderate-,and high-dose group(with oral gavage of soy isoflavones of 100,200,and 300 mg·kg^-1),estrogen group(with oral gavage of diethylstilbestrol of 0.6 mg·kg^-1).After 8 weeks' of treatments,the levels of estradiol,progesterone,testosterone,luteinizing hormone(LH),follicle stimulating hormone(FSH),and sex hormone binding globulin(SHBG)in serum of the rats were detected with enzyme-linked immunosorbent assay(ELISA).Results Compared with those of the control group,the ratio of ovary/body(0.031±0.008),serum LH(3.225±0.405 ng/L) and FSH(1.536±0.186 IU/L) decreased(P<0.05 for all),whereas the serum estradiol(5.177±0.453 μg/L) increased(P<0.05) for the rats of high-dose soy isoflavones group,but no significant differences in uterus/body ratio,serum progesterone,testosterone,and SHBG were observed(P>0.05)in the rats of soy isoflavones groups.Conclusion Soy isoflavone could regulate serum levels of main sex hormones and alleviate the decline of ovarian function in aged female rats.