Influence of phytoestrogens on development of reproductive functions

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In this experiment, effects of phytoestrogens, coumestrol, genistein and resveratrol, on sexual differentiation and reproductive behaviors were examined in the rat.1. Effects of phytoestrogens on masculinization of the brain functions(1) Effects of coumestrol(CM) : Single injection with 3mg CM on day 5 after birth induced acceleration of vaginal opening, acyclic change in vaginial smear, small ovaries without corpus luteum and low lordotic activity in female rats, as injection with 1mg estradiol. On the other hand, no effects were observed when injected with genistein.(2) Effects of resveratrol(RTL) : Single injection with 5mg RTL on day 5 after birth induced acyclic change in vaginal smear in a few rats, but not in most female rats. Lordotic activity was not influenced by injection with RTL.(3) Prevention of masculinizing effects of coumestrol by progesterone : Progesterone is known to suppress functions of estrogen in the brain. In this experiment, simultaneous injection with 3mg CM and 0.5mg progesterone to female pups on day 5 after birth induced no effect on vaginal opening, vaginal smear and lordotic activity. This indicates that progesterone also can prevent masculinizing effect of phytoestrogens.2. Effects of phytoestrogens on lordosis and maternal behavior in adult female rats.(1) Sexual behavior : Ovariectomized rats were injected with 1mg CM and 0.5mg progesterone 44 hrs after injection of CM and lordosis behavior was observed. As a result no effects were observed. No effects were observed even when injected those in ovariectomized rats treated of substhresthold dose of estrogen.(2) Maternal behavior : Injections with 1mg estradiol benzoate daily for 10 days accelerated onset of maternal behavior but lmg CM in ovariectomized rats did not.These results indicate that phytoestrogen is effective in mascuilinizing the brain in the neonatal period but not in facilitation of reproductive behaviors in adult female rats.