@article{losa-ward_todd_mccaffrey_tsutsui_patisaul_2012, title={Disrupted Organization of RFamide Pathways in the Hypothalamus Is Associated with Advanced Puberty in Female Rats Neonatally Exposed to Bisphenol A}, volume={87}, ISSN={["1529-7268"]}, DOI={10.1095/biolreprod.112.100826}, abstractNote={ABSTRACT Hypothalamic neurons, which produce the kisspeptin family of peptide hormones (Kp), are critical for initiating puberty and maintaining estrous cyclicity by stimulating gonadotropin-releasing hormone (GnRH) release. Conversely, RFamide-related peptide-3 (RFRP3) neurons inhibit GnRH activity. It has previously been shown that neonatal exposure to bisphenol A (BPA) can alter the timing of female pubertal onset and induce irregular estrous cycles or premature anestrus. Here we tested the hypothesis that disrupted ontogeny of RFamide signaling pathways may be a mechanism underlying advanced puberty. To test this, we used a transgenic strain of Wistar rats whose GnRH neurons express enhanced green fluorescent protein. Pups were exposed by daily subcutaneous injection to vehicle, 17beta-estradiol (E2), 50 μg/kg BPA, or 50 mg/kg BPA, from Postnatal Day (PND) 0 through PND 3, and then cohorts were euthanized on PNDs 17, 21, 24, 28, and 33 (5–8 animals per age per exposure; males were collected on PNDs 21 and 33). Vaginal opening was advanced by E2 and 50 μg/kg BPA. On PND 28, females exposed to E2 and 50 μg/kg BPA had decreased RFRP-3 fiber density and contacts on GnRH neurons. RFRP3 perikarya were also decreased in females exposed to 50 μg/kg BPA. Data suggest that BPA-induced premature puberty results from decreased inhibition of GnRH neurons.}, number={2}, journal={BIOLOGY OF REPRODUCTION}, author={Losa-Ward, Sandra M. and Todd, Karina L. and McCaffrey, Katherine A. and Tsutsui, Kazuyoshi and Patisaul, Heather B.}, year={2012}, month={Aug} }
 @article{losa_todd_sullivan_cao_mickens_patisaul_2011, title={Neonatal exposure to genistein adversely impacts the ontogeny of hypothalamic kisspeptin signaling pathways and ovarian development in the peripubertal female rat}, volume={31}, ISSN={["0890-6238"]}, DOI={10.1016/j.reprotox.2010.10.002}, abstractNote={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 nucleus (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.}, number={3}, journal={REPRODUCTIVE TOXICOLOGY}, author={Losa, Sandra M. and Todd, Karina L. and Sullivan, Alana W. and Cao, Jinyan and Mickens, Jillian A. and Patisaul, Heather B.}, year={2011}, month={Apr}, pages={280–289} }