Brain aromatase and 5alpha-reductase, regulatory behaviors and testosterone levels in adult rats on phytoestrogen diets.

The purpose of this study was to examine the short-term effects of phytoestrogens in the diet on regulatory behaviors (food/water intake and locomotor activity), prostate weight, testosterone levels, and brain androgen metabolizing enzyme activity levels in adult male rats. Sprague-Dawley rats were fed phytoestrogen-containing versus phytoestrogen-free diets for 29 days. Standard methods were used to measure open field behavior, reproductive, hormonal parameters, and enzymatic activity levels. The phytoestrogen diet contained approximately 200 microg/g of isoflavones whereas in the phytoestrogen-free diet, no phytoestrogens were detected by HPLC analysis. There were no significant differences in any of the regulatory behaviors (food/water intake or locomotor activity), prostate weight, or testosterone levels between the treatment groups. Furthermore, there was no significant influence of phytoestrogens on brain aromatase activity levels, in either the medial basal hypothalamic-preoptic area (MBH-POA) or amygdala brain tissue sites examined. However, significant alterations in MBH-POA and amygdala 5alpha-reductase activities were detected in animals receiving the phytoestrogen-containing versus the phytoestrogen-free diets.