Release of gonadotropins in adult rodents is sex specific and dependent upon kisspeptin (Kiss1) neurons. This crucial pathway within the hypothalamic-pituitary-gonadal (HPG) axis is profoundly influenced by neonatal estrogens, which induce a male-like phenotype. Classically, estrogen activity is mediated via the estrogen receptors a and β (ERα and ERβ), but the relative roles each plays in organizing the sex-specific ontogeny of kisspeptin signaling pathways remain unresolved. Thus, the present study used in situ hybridization histochemistry (ISHH) to map the temporal and sexually dimorphic neonatal mRNA expression profiles of ERα, ERβ, and Kiss1 in the anterioventral periventricular nucleus (AVPV), medial preoptic area (MPOA), ventromedial nucleus (VMN), and arcuate nucleus (ARC), all regions critical for kisspeptin regulation of gonadotropin secretion. In general, females had higher levels of ERα, in all regions examined, a sex difference that persisted until postnatal day (PND) 19 except in the ARC. Males had significantly more ERβ expression in the AVPV at birth, but this sex difference was lost and then re-emerged on PND 19, with females having more than males. VMN ERβ levels were higher in females until PND 19. Kiss1 was not detectable until PND 11 in the anterior hypo-thalamus, but expression levels were equivalent at birth in the ARC. By PND 2, ARC ERα and Kiss1 levels were abundant, sexually dimorphic (higher in females), and, respectively, showed a U- and a bell-shaped pattern with age. Sex differences in ARC Kiss1 expression provide evidence that Kiss1 may play a role in the sexual dimorphic organization of the neonatal brain. These detailed profiles of neonatal Kiss1 and ERs mRNA levels will help elucidate the relative roles each plays in the sex-specific, estrogen-dependent organization of gonadotropin signaling pathways.

Bisphenol A (BPA) exposure is ubiquitous, and in laboratory animals, early-life BPA exposure has been shown to alter sex-specific neural organization, neuroendocrine physiology, and behavior. The specific mechanisms underlying these brain-related outcomes, however, remain largely unknown, constraining the capacity to ascertain the potential human relevance of neural effects observed in animal models. In the perinatal rat brain, estrogen is masculinizing, suggesting that BPA-induced perturbation of estrogen receptor (ESR) expression may underpin later in-life neuroendocrine effects. We hypothesized that prenatal BPA exposure alters sex-specific ESR1 (ERα) and ESR2 (ERβ) expression in postnatal limbic nuclei. Sprague Dawley rats were mated and gavaged on gestational days (GDs) 6-21 with vehicle, 2.5 or 25 μg/kg bw/day BPA, or 5 or 10 μg/kg bw/day ethinyl estradiol. An additional group was restrained but not gavaged (naïve control). Offspring were sacrificed the day after birth to quantify ESR gene expression throughout the hypothalamus and amygdala by in situ hybridization. Relative to the vehicle group, significant effects of BPA were observed on ESR1 and ESR2 expression throughout the mediobasal hypothalamus and amygdala in both sexes. Significant differences in ESR expression were also observed in the mediobasal hypothalamus and amygdala of the naïve control group compared with the vehicle group, highlighting the potential for gavage to influence gene expression in the developing brain. These results indicate that ESR expression in the neonatal brain of both sexes can be altered by low-dose prenatal BPA exposure.

Developmental exposure to Bisphenol A (BPA), a component of polycarbonate and epoxy resins, has been purported to adversely impact reproductive function in female rodents. Because neonatal life is a critical window for the sexual dimorphic organization of the hypothalamic-pituitary-gonadal (HPG) axis, interference with this process could underlie compromised adult reproductive physiology. The goal of the present study was to determine if neonatal BPA exposure interferes with sex specific gene expression of estrogen receptor alpha (ERα), ER beta (ERβ) and kisspeptin (Kiss1) in the anterior and mediobasal hypothalamus. Long Evans (LE) neonatal rats were exposed to vehicle, 10 µg estradiol benzoate (EB), 50 mg/kg BPA or 50µg/kg BPA by subcutaneous injection daily from postnatal day 0 (PND 0) to PND 2. Gene expression was assessed by in situ hybridization on PNDs 4 and 10. Within the anterior hypothalamus ERα expression was augmented by BPA in PND 4 females, then fell to male-typical levels by PND 10. ERβ expression was not altered by BPA on PND 4, but significantly decreased or eliminated in both sexes by PND 10. Kiss1 expression was diminished by BPA in the anterior hypothalamus, especially in females. There were no significant impacts of BPA in the mediobasal hypothalamus. Collectively, BPA effects did not mirror those of EB. The results show that neonatal hypothalamic ER and Kiss1 expression is sensitive to BPA exposure. This disruption may alter sexually dimorphic hypothalamic organization and underlie adult reproductive deficiencies. Additionally, the discordant effects of EB and BPA indicate that BPA likely disrupts hypothalamic organization by a mechanism other than simply acting as an estrogen mimic.

Summary SentenceNeonatal genistein exposure at physiologically relevant levels advances vaginal opening, disrupts ovarian development and defeminizes the ontogeny of kisspeptin signaling pathways in the female rat hypothalamus.Neonatal exposure to estrogenic endocrine disrupting compounds (EDCs) can advance pubertal onset and induce premature anestrous in female rats. It was recently discovered that hypothalamic kisspeptin (KISS) signaling pathways are sexually dimorphic and regulate both the timing of pubertal onset and estrous cyclicity. Thus we hypothesized that disrupted sex specific ontogeny of KISS signaling pathways might be a mechanism underlying these EDC effects. We first established the sex specific development of KISS gene expression, cell number and neural fiber density across peripuberty in the anteroventral periventricular nucleus (AVPV) and arcuate (ARC), hypothesizing that the sexually dimorphic aspects of KISS signaling would be most vulnerable to EDCs. We next exposed female rats to the phytoestrogen genistein (GEN, 1 or 10 mg/kg bw), estradiol benzoate (EB, 10 μg), or vehicle from post natal day (P) 0-3 via subcutaneous (sc) injection. Animals were sacrificed on either P21, 24, 28, or 33 (n = 5-14 per group at each age). Vaginal opening was significantly advanced by EB and the higher dose of GEN compared to control animals and was accompanied by lower numbers of KISS immunoreactive fibers in the AVPV and ARC. Ovarian morphology was also assessed in all age groups for the presence of multiple oocyte follicles (MOFs). The number of MOFs decreased over time in each group, and none were observed in control animals by P24. MOFs were still present, however, in the EB and 10 mg/kg GEN groups beyond P24 indicating a disruption in the timing of ovarian development.

EGCG [(-)-epigallocatechin-3-gallate] has shown its antitumor ability and perhaps a potential regimen for cancer patients. The goal of this study was to investigate the effect of EGCG on human papilloma virus (HPV) positive cervical cancer cell lines. EGCG inhibited the growth of CaSki (HPV16 positive) and HeLa (HPV18 positive) cells in a time- and concentration-dependent manner. Cell cycle arrest and apoptosis were observed in two cell lines after EGCG exposure. More importantly, we focused on EGCG regulation ability on pivotal genes involved in cervical cancer: viral oncogenes E6/E7, estrogen receptor (ER) and aromatase. Our results suggested that EGCG may be suitable for prevention and treatment of cervical cancer.