Concerns have been raised about the possible role of the phytoestrogen genistein and the xenoestrogen Bisphenol A (BPA) as endocrine disruptors. In the present study, we examined the effects of fetal exposure to genistein and BPA on the Mitogen-activated protein kinase (MAPK) pathway and on testicular cell populations in neonatal and adult rat testes. At postnatal day (PND) 3, genistein (0.1-10 mg/kg/day) and BPA (1-200 mg/kg/day) induced Raf1 and Erk1/2 mRNA and protein increases in testes, mainly in Sertoli cells. No changes were seen for Mek1. At PND60, Erk1/2 protein expression remained robust in Sertoli cells and in some spermatogonia. Raf1 was predominant in Leydig cells while Mek1 was expressed strongly in spermatogonia, and they were both expressed in pachytene spermatocytes. No consistent change was seen in these proteins at PND60. Transient effects were observed on germ cell populations, while the only remaining effect on adult testicular cells was an increase in Leydig cell number. Rats exposed in utero to the two compounds did not present significant changes in circulating testosterone levels, suggesting normally functioning adult Leydig cells. Furthermore, Sertoli cell numbers were not affected by exposure to genistein and BPA. Finally, around 10% of genistein and BPA exposed rats were sterile, whereas all control rats were fertile. These data suggest that fetal exposure to genistein and BPA exerts transient effects in rat testes and that the changes observed at PND3 did not correlate with relevant changes in germ cell populations, Leydig cell function, or fertility in the adult.
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