Selective estrogen receptor modulator-like gene expression in prepubertal rat testis after soy feeding

In this study, we investigated the potential estrogenicity of soy protein isolate (SPI) as opposed to pure isoflavones (i.e., estradiol) in the prepubertal stage of testis development. Bioinformatics analysis of the microarray analysis indicate that rather than acting as a weak estrogen in the developing testis, SPI appears to act as a selective estrogen receptor modulator with little effect on reproductive processes. Weanling male Sprague-Dawley rats were fed with a semi-purified diet with casein or SPI from postnatal day 21 to 33. Additional groups were feed with casein or SPI and treated s.c. with 10 ug/kg/d estradiol via osmotic minipump.