RESUMO
INTRODUCTION: Phytoestrogens are a wide variety of chemical compounds, mainly isoflavonoids, from a vegetable source. Their name makes reference to their ability to induce estrogenic responses in mammals. Coumestrol is a phytoestrogen that can be found in high concentrations in the dietary elements of cattle. Some endocrine alterations have been reported for cows and ewes after ingestion of vegetables with high concentrations of coumestrol. However, these studies have been made mainly in females. OBJECTIVE: To analyze some features of the masculine endocrine response in rats after several doses of the phytoestrogen coumestrol. DESIGN: Adult male rats were injected with several doses of coumestrol. Plasma gonadotrophins (LH/FSH) and testosterone levels were assessed. In addition, morphology of the testicles was analyzed. SETTING: Experiments were done in the facilities of the neurosciences area at the University. RESULTS: No significant changes were observed in gonadotrophin levels after the administration of coumestrol. Testosterone levels showed a significant decrease with the higher doses. Morphological analysis showed an inhibitory effect on spermatogenesis expressed mainly in the right testicle. Testicular volume decreased and the tubular area increased significantly after coumestrol treatment. CONCLUSIONS: These results suggest that the endocrine effect of coumestrol is mainly expressed in peripheral targets in male rats. In addition, the possible mediation of estrogen beta receptors is discussed.