MON-031 In Vitro Exposure to Bisphenol A, Benzophenones 2 or 3, Have Different Effects on GnRH Gene Expression and Secretion in Mature and Immature GnRH Neurons

Abstract

Bisphenol A, (BPA), a component of polycarbonate plastics, and Benzophenones (BPs), UV filters, are endocrine disrupting chemicals (EDC). Previously we showed that the in vitro exposure to BPA decreased Kiss-induced GnRH expression in GN11 cells (Dr. Susan Wray, NIH), immature GnRH neurons (1). In this study, we analyzed the in vitro effects of BPA, BP2 and BP3 (1x10-9M), or medium as control (C) in mature GnRH neurons (GT1-7 cells, donated by Dr Pamela Mellon, UCSD, USA, and isolated hypothalami from adult Balb/c males). Effects of BP2 and BP3 (1x10-9M) were also analyzed in GN11 cells. We exposed the cell lines for 24 h and the hypothalami for 6 h to the EDC. GT1-7 and GN11 cells were further incubated with Kiss (1x10-9M, Phoenix Pharmaceuticals, Inc, CA, USA) for 4 h to analyze gene expression (qPCR) and for 1 h to analyze GnRH secretion (RIA). Hypothalami exposed to BPA showed increased GnRH expression compared to C (Relative expression: C:1.0±0.2; BPA:2.2±0.5; Student T-test: BPA vs C p<0.05, n=9), whereas neither BP2 nor BP3 had any effect (ANOVA: ns). There was no effect on GnRH secretion (ANOVA: ns). GT1-7 cells exposed to C showed Kiss-induced GnRH gene expression, while the exposure to the EDC abolished this response (Relative expression: C-Basal:1.0±0.1, C-Kiss:1.6±0.3, BPA-Basal:1.3±0.2, BPA-Kiss:1.1±0.2, BP2-Basal:1.2±0.1, BP2-Kiss:1.4±0.2, BP3-Basal:1.3±0.3, BP3-Kiss:1.1±0.2; Repeated measures Two-way ANOVA: Interaction p<0.05, n=6). There was no difference in Kiss-stimulated GnRH release in EDC-exposed cells vs C-exposed cells (Repeated measures Two-way ANOVA: Interaction ns; Main Effect: Time of Kiss exposure: p<0.01, n=7). In GN11 cells, exposure to BP2 inhibited Kiss-induced GnRH gene expression, whereas there was no such effect in cells exposed to BP3 (Relative Expression: C-Basal:1.1±0.02, C-Kiss:1.3±0.1, BP2-Basal:1.2±0.1, BP2-Kiss:1.0±0.1, BP3-Basal:1.0±0.1, BP3-Kiss:1.3±0.1; Repeated measures Two-way ANOVA: Interaction p<0.01, n=8). Exposure to BP3 significantly increased GnRH secretion and abolished the response to Kiss, whereas BP2 significantly decreased Kiss-stimulated release [GnRH (pg/ml): C-Basal: 8.5±1.3, C-Kiss: 32.9±8.8, BP2-Basal: 16.5±4.9, BP2-Kiss: 16.9±5.1, BP3-Basal: 18.0±3.2, BP3-Kiss: 20.8±5.6, Repeated measures Two-way ANOVA: Interaction p<0.05; C-Kiss vs C-Basal, BP3-Basal vs C-Basal, BP2-Kiss vs C-Kiss p<0.05, n=9]. Our results show that EDC exposure alters the physiology of mature and immature GnRH neurons, although effects are different in the two cell lines, and they also differ in mature GnRH neurons vs hypothalamus. Further studies are needed to dissect the mechanisms involved. 1- Endoc. Rev. 38(3S), SAT-256, 2017. Nothing to disclose. Funding: CONICET, ANPCyT, UBA, International Society for Neurochemistry, Asoc. ORT Arg., Fund. R. Barón, Fund. Williams.