Lack of functional estrogen receptor β gene disrupts pubertal male sexual behavior

The estrogen receptor-β (ERβ) mediates estrogen action in the female gonads, reproductive tract, and central nervous system. In addition, in rats and mice, gonadotropin-releasing hormone (GnRH-I) neurons coexpress ERβ. Here we asked if ERβ plays a role in the onset of puberty and in hypothalamic-pituitary-gonadal (HPG) axis function in male mice. We examined mating behavior, testosterone concentrations, steroid negative feedback on gonadotropins, and GnRH-I function in male ERβ knockout (ERβKO) and wild-type (WT) mice. Peripubertal ERβKO males displayed their first ejaculation at a significantly older age than WT littermates. Castrated, adult ERβKO mice had significantly higher plasma luteinizing hormone (LH) than WT counterparts. Estradiol (E2) treatment reduced LH and follicle stimulating hormone (FSH) concentrations to an equivalent degree in castrates of both genotypes. In three different measures of the adult GnRH-I system, no genotypic differences were observed. These data show that ERβ plays an important role in the timing of male sexual behavior at puberty, but does not appear to be involved in adult HPG axis functioning. Furthermore, our data suggest that a primary role of ERβ may be to regulate ejaculatory behavior.