Endocrine Abstracts

One of the most common environmental endocrine disruptor is bisphenol A (BPA), which mimics estrogen effects. Even at low expositional dose, BPA is capable of transferring across the human placenta in active unconjugated form. The purpose of this work was to investigate the long-term effects of low dose BPA introduction to rats during the critical period of sexual differentiation of the brain on the reproductive system and the behavior of F1 offspring. Wistar dams were exposed from 15 to 21 gestational day to BPA (by gavage, 25 µg/kg bw/day), or a reference estrogen (s/c, 10 µg estradiol diacetate (E2D)/kg bw/day), or were intact. The morphology of the reproductive organs and the male and female types sexual behavior were studied in adult offspring of both sexes. In males, BPA did not change the weight of testes, accessory sex glands, morphology of testicles and ventral prostate (VP), the number of sperm in the epididymis and the blood plasma levels of testosterone (T) and estradiol (E2) compared with intact males. However, almost complete inhibition of the copulatory components of male sexual behavior was observed. BPA-exposed males primed with E2 and progesterone showed pronounced lordosis behavior in the presence of a sexually active male. Prenatal E2D caused significant loss of the VP weight and degenerative changes in the epithelium of the VP. Males of the E2D group showed enhanced sexual motivation and copulatory behaviors on the background of significantly increased level of T. Besides, these males demonstrated active female and homosexual sexual behavior in the presence of sexually active male. None of the drugs affected the structure and duration of estrous cycle. The blood plasma E2 levels in the females of both groups were reduced. BPA caused degeneration of the follicular epithelium in part of the secondary and tertiary ovarian follicles with no changes in the number of follicles. Either prenatal BPA or E2D affected female type sexual behavior of female offspring. Female оf BPA and E2D groups exhibited male sexual behavior (5 from 5 and 4 from 5 animals respectively). We concluded that prenatal exposure to BPA at a dose below the currently acceptable human daily intake violates sexual differentiation of developing brain.

Keywords: bisphenol A, rat, prenatal effect, sexual differentiation, brain, behavior, testosterone, estradiol, male, female