Maternal oral exposure to low-dose BPA accelerates the onset of puberty by promoting prepubertal Kiss1 expression in the AVPV nucleus of female offspring.

ABSTRACT

As the incidence of precocious puberty has risen in recent years and the age at puberty onset is younger, children may be at increased risk for health consequences associated with the early onset of puberty. Bisphenol A (BPA) is recognized as an endocrine disruptor chemical that is reported to induce precocious puberty. The effect of BPA exposure modes, times, and doses (especially low dose) were controversial. In the present study, we evaluated the potential effects of maternal exposure to low-dose BPA on the hypothalamus, particularly on the arcuate (ARC) nucleus and anteroventral periventricular (AVPV) nucleus during peri-puberty in offspring of BPA-treated rats. Pregnant rats were exposed to corn oil vehicle, 0.05 mg·kg-1·day-1 BPA, or 5 mg·kg-1·day-1 from gestation day 1 (GD1) to postnatal day 21 (PND21) by daily gavage. Body weight (BW), vaginal opening (VO), ovarian follicular luteinization, and relevant hormone concentrations were measured; hypothalamic Kiss1 and GnRH1 levels by western immunoblot analysis were also assessed as indices of puberty onset. During or after exposure, low-dose BPA restricted BW after birth (at PND1 and PND5), and subsequently accelerated puberty onset by promoting the expression of prepubertal Kiss1 and GnRH1 in the AVPV nucleus on PND30, leading to advanced VO, an elevation in LH and FSH concentrations (on PND30). We also noted increased BW on PND30 and PND35. Maternal oral exposure to low-dose BPA altered the BW curve during the neonatal and peripubertal periods, and subsequently accelerated puberty onset by promoting prepubertal Kiss1 expression in the AVPV nucleus.