Estrogen regulates testicular steroidogenesis, acting via ERα because administration of an estrogenic chemical, estradiol benzoate, suppressed pituitary LH secretion and serum testosterone levels in wild-type but not αERKO mice (ref. 67)(A). ERα deficiency enhanced gene expression for cytochrome P450 hydroxylase/17α lyase and 17β-hydroxysteroid dehydrogenase type III in αERKO Leydig cells compared to wildtype (WT) (B), indicating that ERα regulates androgen biosynthesis by mediating changes in steroidogenic enzyme activity (ref. 67). Copyright 2003, The Endocrine Society.