There are human reproduction concerns associated with extensive use of bisphenol A (BPA)-containing plastic and, in particular, the leaching of BPA into food and beverages. In this context, it remains unclear whether and how exposure to BPA interferes with the developmental organization and adult activation of male sexual behavior by testosterone. We evaluated the developmental and adult exposure to oral BPA at doses equivalent to the no-observed-adverse-effect-level (5 mg/kg body weight per day) and tolerable daily intake (TDI) (50 μg/kg body weight per day) on mouse sexual behavior and the potential mechanisms underlying BPA effects. Adult exposure to BPA reduced sexual motivation and performance at TDI dose only. Exposed males took longer to initiate mating and reach ejaculation despite normal olfactory chemoinvestigation. This deficiency was not restored by sexual experience and was associated with unchanged circulating levels of testosterone. By contrast, developmental exposure to BPA at TDI or no-observed-adverse-effect-level dose did not reduce sexual behavior or alter the neuroanatomical organization of the preoptic area. Disrupting the neural androgen receptor resulted in behavioral and neuroanatomical effects similar to those induced by adult exposure to TDI dose. Moreover, adult exposure of mutant males to BPA at TDI dose did not trigger additional alteration of sexual behavior, suggesting that BPA and neural androgen receptor mutation share a common mechanism of action. This shows, for the first time, that the neural circuitry underlying male sexual behavior is vulnerable to chronic adult exposure to low dose of BPA and suggests that BPA could act in vivo as an antiandrogenic compound.

Motoneurons in the spinal nucleus of the bulbocavernosus (SNB) and their target bulbocavernosus (BC) and levator ani (LA) muscles play a role in male copulation and fertility. Testosterone (T) induces sexual differentiation of this SNB neuromuscular system during development and maintains its activation in adulthood. In the rat, T-induced effects mostly involve the androgen receptor (AR). However, the role of central AR in T-induced effects remains to be studied with pertinent genetic models. We addressed this question by using specific motoneuron immunolabeling and retrograde tracing in mice selectively disrupted for AR in the nervous system. This work reveals that nervous system AR is not required either for T-induced development of BC-LA muscles and perinatal sparing of SNB motoneurons from atrophy or for adult sensitivity of BC-LA muscles to T. By contrast, loss of AR expression in the nervous system resulted in SNB motoneurons having smaller somata and shorter dendrites than controls. We studied the effects of adult castration and T supplementation on SNB cell morphology in control and mutant males; these experiments showed that central AR is involved in the developmental regulation of soma size and dendritic length and in the adult maintenance of soma size of SNB motoneurons. T seemed to act indirectly through BC-LA muscles to maintain dendritic length in adulthood. Our results also suggest that central AR functions may contribute to normal activity of SNB motoneurons and perineal muscles because mutant mice displayed diminished copulatory behavior and fertility.

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Estradiol derived from neural aromatization of gonadal testosterone plays a key role in the 27 perinatal organization of the neural circuitry underlying male sexual behavior. The aim of this 28 study was to investigate the contribution of neural estrogen receptor (ER)  in estradiol-29 induced effects without interfering with its peripheral functions. For this purpose, male mice 30 lacking ER in the nervous system were generated. Analyses of males in two consecutive 31 tests with a time interval of two weeks showed an effect of experience, but not of genotype, 32 on the latencies to the first mount, intromission, pelvic thrusting and ejaculation. Similarly, 33there was an effect of experience, but not of genotype, on the number of thrusts and mating 34 length. Neural ER deletion had no effect on the ability of males to adopt a lordosis posture in 35 response to male mounts, after castration and priming with estradiol and progesterone.