[Effect of dietary genistein on rats development exposure after their weaning]

To investigate the effects of dietary genistein on the development of young rats.

SD rats aged three-week were randomly divided into three groups according to their weight (eight male and eight female). Each group was fed a diet containing genistein at levels of 0, 20 and 100 mg/kg. Several development indices were observed each week. At the age of 9 weeks, blood samples were collected and the plasma estradiol level of female rats and plasma testosterone level of male pups were measured. At the age of 13 weeks, organs( ovary and uterns in female, testes in male) were examined for histopathological changes and the expression of the estrogen receptor was measured by Western blotting.

The plasma estradiol level of female rats increased and the plasma testosterone level of male rats decreased at the age of 9 weeks compared to the control group. At the age of 13 weeks, decreased body weight, food consumption, anogenital distance (AGD) and overy weight in female rats were observed. Also, the vaginal open time of female pups was earlier than control group. Histopathology showed that the cavity of uterus was larger than control group. Otherwise, treatment with genistein caused reduction in the plasma estradiol level of female rats and the expression of estrogen receptor-alpha in uterus. There were few changes of male rats' body weight, testicular descent, testes weight and histopathology except that the increased food consumption from 10-week-old and plasma testosterone level.

Genistein exposure could effect on both sexes of young rats' development. The effects on female rats were much more than that on male rats and the effect of rats body weight and food consumption was mainly after their growing up. Although the mechanism of these effects are still obscure, it seems that the change of hormone level and expression of estrogen receptor have some relation with these effects.