Neonatal exposure to coumestrol, a phytoestrogen, does not alter spermatogenic potential in rats.

The objective of this study was to determine the effects of neonatal exposure to phytoestrogens on male reproductive function as adults. Male rats were injected either with 100 micrograms coumestrol or DMSO (controls) daily during their first 5 d of life. Pituitary gland, testes, sex accessory organs, and blood were collected on d 60 of life. Serum testosterone, LH, and FSH levels were determined by RIA. Levels of steady-state mRNA for gonadotrophin subunits (LH beta and FSH beta were determined by Northern blot analysis and quantified by a scanning densitometer. Coumestrol had no effect on weights of testes and sex accessory organs, or sperm count. Similarly, there were no significant differences among serum concentrations of testosterone, LH beta and FSH of coumestrol-treated rats and those of controls. Whereas steady state levels of LH beta mRNA in coumestrol-treated rats did not differ from those of controls, steady state levels of FSH beta mRNA increased (37%) in treated animals. However, the augmented FSH beta mRNA expression in coumestrol-treated rats did not negatively affect reproductive potential in male rats. We conclude that neonatal exposure to coumestrol does not alter reproductive organ structure or spermatogenic potential in male rats.