Neonatal Treatment with Bisphenol A Decreased Cell Proliferation and GnRH Gene Expression in Adult Rat Ovary.

BOURGUIGNON NS; FERNANDEZ MO; LUX LANTOS V; LIBERTUN C

S. Diego, California

Congreso; The Endocrine Society (USA). 92th Annual Meeting; 2010

The Endocrine Society

[P2-59] Neonatal Treatment with Bisphenol A Decreased Cell Proliferation and GnRH Gene Expression in Adult Rat Ovary.NS Bourguignon, MO Fernandez, VAR Lux Lantos, C Libertun. Inst de Biol y Med Experimental-CONICET, Buenos Aires, Argentina; Fac de Med, Univ de Buenos Aires, Buenos Aires, ArgentinaBisphenol A, (BPA), a component of polycarbonate plastics, epoxy resins and polystyrene found in many common products, is a xenoestrogen that alters several functions in different species, including rats and humans. Previously we described the effects of this endocrine disruptor on the hypothalamic-pituitary-gonadal axis in female rats (1). Following this research line, in this study we analyzed the effects of neonatal exposure to BPA on granulosa and theca cell proliferation, as well as GnRH gene expression, in ovaries of adult rats.Female Sprague-Dawley rats were injected sc, daily from postnatal day (PND)1 to 10 with BPA: 500 µg/50 µl oil (H), or 50 µg/50 µl oil (L), or solvent as control (C). In adults (PND120-160), euthanized by decapitation in the morning of estrus following Institutional Ethical Standards, one ovary of each animal was immediately fixed in 5% neutral buffered formaldehyde for histological examination. Cell proliferation in early preovulatory follicles was determined in ovarian sections by immunohystochemistry of the proliferating cell nuclear antigen (PCNA) in theca (TC) and granulosa (GC) cells, as described in (2). Results were expressed as PCNA positive cells/total cells. In the second ovary, GnRH mRNA levels were determined using real-time PCR as described in (3). Results were expressed as means ± SE and considered significant when p<0.05. Data were analyzed by one-way analysis of variance.Animals treated with high-dose BPA showed a decrease of GC [C: 51.42±3.45 (n=5); L: 39.75±6.92 (n=5); H: 17.20± 3.54 (n=5), p<0.001] and TC [C: 42.46±3.58 (n=5); L 38.59±9.49 (n=5); H: 13.40± 4.15 (n=5), p<0.02] proliferation. A dramatic reduction in GnRH mRNA expression was found even with the lower dose [Arbitrary Units; C: 0.8136±0.1279 (n=5); L: 0.0862± 0.0333 (n=4); H: 0.0043± 0.0021(n=4), p<0.001].Neonatal exposure to BPA decreased ovarian granulosa and theca cell proliferation, as well as GnRH mRNA expression, in ovaries of adult rats. These results show that exposure to BPA during the neonatal period irreversibly alters ovarian physiology in adulthood, long after the exposure to the agent ceased. Exposure to BPA during ontogeny could contribute to the development of many reproductive disorders of increased incidence in humans.(1) Fernández M et al., Environ Health Perspect 2009; 117:757(2) Abramovich D et al., Fertil Steril 2009. In press.(3) Schirman- Hildesheim TD et al., Endocrinology 2005; 146:3401Sources of Research Support: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Agencia Nacional de Promoción Científica y Tecnológica; Universidad de Buenos Aires. Argentina.