Do phytoestrogens affect reproductive performance in male rats?

Daidzein and genistein are important soy-borne phytoestrogens that have been implicated in human health. In this study, independent effects of diadzein and genistein were tested on fertility output in male rats. Adult male Wistar rats (90 days old) were subjected to weekly injections of 2, 20, 100 mg/kg BW daidzein or genistein dissolved in DMSO for 8 weeks. Following treatment, control and experimental males were cohabited with sexually mature normal females for 5 days. Female rats were sacrificed and autopsy was performed on day 18 of pregnancy when uterus and ovaries were examined for the numbers ofcorpora lutea, implantations, dead and live fetuses and resorptions. No significant changes (p > 0.05) were observed in the body weight gain of experimental males. Similarly, no changes (p > 0.05) were observed in themating and fertility index. In contrast, significant decrease (p < 0.05) was observed in fertility rate, measured by counting numbers of live fetuses in the uterus offemales mated with males exposed to either daidzein or genistein.Females mated to daidzein exposed males showed resorptions and a significant decrease (p < 0.05) in number of live fetuses per rat. These data demonstrate that significant decrease in fertilization capacity of adult male rats exposed to either daidzein or genistein.