Brain aromatase and 5 alpha-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 phytoest rogens in the diet on regulatory behaviors (food/water intake and locomotor activity), prostate weight, testosterone levels, and brain androgen metabo lizing enzyme activity levels in adult male rats. Sprague-Dawley rats were fed phytoestrogen-containing versus phytoestrogen-free diets for 29 days. S tandard methods were used to measure open field behavior, reproductive, hor monal parameters, and enzymatic activity levels. The phytoestrogen diet con tained approximate to 200 mu g/g of isoflavones whereas in the phytoestroge n-free diet, no phytoestrogens were detected by HPLC analysis. There were n o significant differences in any of the regulatory behaviors (food/water in take or locomotor activity), prostate weight, or testosterone levels betwee n the treatment groups. Furthermore, there was no significant influence of phytoestrogens on brain aromatase activity levels, in either the medial bas al hypothalamic-preoptic area (MBH-POA) or amygdala brain tissue sites exam ined. However, significant alterations in MBH-POA and amygdala 5 alpha-redu ctase activities were detected in animals receiving the phytoestrogen-conta ining versus the phytoestrogen-free diets.