The Effect of Estrogen Analogues on the Development of the Testis, Epididymis, and Penis in Rats.

Abstract

Studies suggest that the use of ethinyl estradiol (EE), a semi-synthetic estrogen used in oral contraceptives, may have adverse effects on the development of the male reproductive tract. The objective of the current study was to determine the effects of neonatal exposure of EE on the penis, accessory sex organs and serum testosterone in rats. Neonatal male rats were administered one of the following treatments: 0ng EE (n=5), 10ng EE (n=5), 100ng EE (n=5), 1μg EE (n=4), or 10 μg EE (n=6) on postnatal days (PND) 2, 4, 6, 8, 10 and 12. On d50, the animals were sacrificed and the penis, seminal vesicle, epididymis and serum testosterone was evaluated. Testicular weights showed a linear decline with increased EE at 3.59g, 3.37g, 3.03g, 2.41g, and 1.39g, respectively. Similarly, epididymal head and body weights showed a linear decline with increased EE at 0.68g, 0.64g, 0.57g, 0.49g and 0.312g, respectively. Epididymal tail weights followed a similar trend with increased EE at 0.49g, 0.46g, 0.45g, .035g and 0.319g, respectively. Further, penis length and penis weight declined linearly with increased EE from 41mm to 29mm and 0.290g to .092g, respectively. These findings support the hypothesis that neonatal exposure to estrogens can negatively affect proper reproductive tract development in rats. This is of great importance, as PND one to six in rats corresponds to the first trimester in humans, suggesting that in utero exposure to estrogens, such as EE, may have pleiotropic effects on the development of the male reproductive tract. (poster)