Bisphenol A exposure advances puberty onset by changing Kiss1 expression firstly in arcuate nucleus at juvenile period in female rats

Bisphenol A (BPA) is ubiquitous in the environment and its adverse effects on precocious puberty have been reported. But its mechanism is not clear. In the present study, the potential effects of BPA on endocrine functions of hypothalamus, especially in the arcuate (ARC) nucleus and anteroventral periventricular (AVPe) nucleus, were studied from postnatal day 15 (PND15) to PND35 in female Sprague-Dawley (SD) rats. Neonatal rats were exposed to 0.5 mg.kg-1.day-1 BPA or corn oil vehicle from PND1 to PND14 via intramuscular injection. From PND20 to PND 25, BPA caused enrichment of H3K4me2 and H3K4me3 at Kiss1 promoter, concurrent with elevated gene expressions of Kiss1 and GnRH1 in ARC and strikingly increased serum E2 levels in BPA group on PND25. Until PND30, BPA induced obviously overexpression of Kiss1 and GnRH1 in AVPe nucleus. Subsequently, the vagina opening and first ovulation had occurred earlier in rats with BPA exposure in respect to vehicle by PND35. In this study, it is suggested that the effects of BPA on precocious puberty may be due to its action to activate Kiss1 gene in ARC during the juvenile period (from PND20 to PND25) firstly, subsequently to evoke the AVPe neurons, resulting in precocious puberty in the end.