EFFECTS OF COUMESTROL AND EQUOL ON THE DEVELOPING REPRODUCTIVE-TRACT OF THE RAT

The phytoestrogens, coumestrol and equol, are weakly estrogenic, Here, we have examined their ability to induce responses in the neonatal ra t uterus. Patent estrogens such as diethylstilbestrol (DES) and 17 bet a-estradiol which initially double uterine weight on postnatal Day (PN D) 5 when given on PHD 1-5 subsequently reduce both uterine growth and gland development at later ages, In this study, Sprague-Dawley pups w ere treated neonatally (PND 1-5) with various doses of coumestrol and equol, and sacrificed at different ages to determine alterations in bi ochemical and morphological endpoints. Other rats were injected with t he same compounds during the critical period of gland genesis (PND 10- 14) to examine their effects on gland development At the 100 mu g coum estrol dose, on PND 1-5, premature gland development and increased ute rine weight were observed, However, at later ages, uterine weight was significantly lowered and them was a severe suppression in the estroge n receptor (ER) revels, Equal lowered uterine weight at the later ages but did not affect ER levels, When given on PND 10-14, both coumestro l and equol caused a dose-dependent inhibition of gland genesis though not as severe as either DES or tamoxifen, Coumestrol was about 10(3) more potent than equal as an estrogen and behaved much like DES with r espect to its effects on uterine weight, glands, and ER levels. At the doses used in this study, equol failed to demonstrate either estrogen ic or antiestrogenic activity.