PHYTOESTROGEN INFLUENCES ON THE DEVELOPMENT OF BEHAVIOR AND GONADOTROPIN FUNCTION

The effect of phytoestrogens on the sexual differentiation of gonadotr opin function was examined by neonatal exposure of pups through milk o f rat dams fed a coumestrol (100 mu g/g), control, or chow diet during the ''critical period'' of the first 10 postnatal days or throughout the 21 days of lactation. In females, exposure to coumestrol throughou t the period of lactation produced growth suppression and an acyclic c ondition in early adulthood resembling the premature anovulatory syndr ome. When the period of treatment was restricted to the first 10 postn atal days, however, no effects on vaginal cyclicity were seen. The 10- day exposure period produced more marked effects in males, resulting i n transitory reductions in body weight in wealing males and reductions in mount and ejaculation frequency and a prolongation of the latencie s to mount and ejaculate. Testicular weights and plasma testosterone l evels did not differ among treatment groups, suggesting that the defic its in male sexual behavior were not due to deficits in adult gonadal function. Few effects of chow treatment were observed. However, signif icant differences from controls were apparent for weight at vaginal op ening in females, and mount rate for chow-treated males was intermedia te between that of controls and that of the coumestrol-treated group. These data provide evidence that lactational exposure to phytoestrogen diets can alter neuroendocrine development in both female and male ra ts.