Effects of short-term and long-term administration of bisphenol A on sex behavior, body weight, and uterine weight in adult female ovariectomized rats
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Bisphenol A [2,2-bis(4-hydroxyphenyl) propane (BPA)] is a chemical that is produced in large amounts worldwide as an additive in polycarbonate plastics that may have adverse effects on human health. BPA is characterized as an endocrine disruptor, or an environmental estrogen, which is a chemical that binds to estrogen receptors and may mimic estrogenic action. While some findings have shown that BPA does in fact mimic estrogen, other research has shown that BPA may act as an anti-estrogen by blocking estrogen receptors. Substantial research has examined the effects of developmental exposure to BPA, but fewer studies have focused on the effects of exposure to BPA in adulthood. The possible hormonal effects of BPA in adults can be examined using the female rat sex behavior model. Female sex behavior is estrogen dependent and has been shown to be adversely influenced by anti-estrogens. Therefore, the aim of the current set of studies is to examine whether short-term or long-term administration of BPA may facilitate or inhibit estrogen-induced female rat sex behavior. In Experiment 1, thirty-six female rats were divided into four experimental groups. Animals received two injections of 1) 2.0 µg estradiol benzoate (EB) or a sesame oil vehicle and 2) 40 mg/kg BPA or a 10% EtOH in sesame oil vehicle. Animals received 500 µg of progesterone approximately 48 hours after initial injections and 4 hours before being observed with sexually active male rats for sexual receptivity. In Experiment 2, the same thirty-six animals received two daily injections of 1) 5.0 µg/day EB or a sesame oil vehicle and 2) 50 µg/kg/day BPA or a 10% EtOH in sesame oil vehicle for a total of 15 days. Animals were tested with sexually active males for sexual receptivity on days 3, 6, and 14 of treatment. In both Experiment 1 and 2, there was a significant main effect of EB treatment on sexual receptivity, such that EB-treated groups showed significantly higher levels of sexual receptivity than animals treated with oil. However, there was no effect of BPA treatment on sexual receptivity. BPA did not inhibit receptivity in the presence of EB or facilitate receptivity in combination with EB or alone. There was a similar pattern in the results of body weight and uterine weight in that there was a significant main effect of EB but not BPA.
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