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THE EFFECTS OF ETHINYL ESTRADIOL ON SPERMATOGENESIS IN THE ADULT MALE RAT
Citation:
Zorrilla, L. M., K. H. Brown, L. F. STRADER, AND T. E. STOKER. THE EFFECTS OF ETHINYL ESTRADIOL ON SPERMATOGENESIS IN THE ADULT MALE RAT. Presented at Triangle Consortium of Reproductive Biology, Research Triangle Park, NC, February 06, 2010.
Impact/Purpose:
Recently, increases in male infertility have been attributed to exposure to environmental estrogens. Decreased sperm concentrations and increased infertility have been reported in the human, while many reports have documented reproductive effects due to estrogenic exposure in animals in laboratory studies as well as in the wild.
Description:
Recently, increases in male infertility have been attributed to exposure to environmental estrogens. Decreased sperm concentrations and increased infertility have been reported in the human, while many reports have documented reproductive effects due to estrogenic exposure in animals in laboratory studies as well as in the wild. Ethinyl estradiol (EE2) is a highly potent synthetic estrogen used as the primary estrogen in birth control pills. Several reports have shown that gestational and neonatal exposure to EE2 causes a decrease in reproductive tissue weights and reduced sperm counts. In the adult male rat, similar effects on tissue weights and sperm counts have been noted. In male rainbow trout exposed to an environmentally relevant dose of EE2 (10 ngIL) for 50 days, analysis of epididymal sperm showed the presence of between 25-36% aneuploidy sperm. Such chromosomal abnormalities can cause pregnancy termination, congenital malformations and mental and physical retardation; however, no studies have examined whether mammalian exposure to EE2 would cause similar effects at an environmentally relevant dose. To test this, we orally exposed adult male Sprague-Dawley rats to 0, 0.5, 5, or 50 J,J.g!kg EE2 for 60 days and sacrificed animals 10 days after the last dose. Trunk blood was collected for hormonal analyses, body weights and reproductive organ weights were recorded, and the testes and epididymides were collected for sperm analyses and fluorescent in situ hybridization (FISH) analyses. Males dosed with 50 J-lg/kg of EE2 had significantly lower body weights compared with controls throughout the duration of the study. This dose group also had significantly increased pituitary weights at the termination ofthe study; no other tissue weights were affected. Testosterone, luteinizing hormone and prolactin levels and sperm motility parameters (velocity, motion parameters) were also not affected by EE2 treatment. Epididymal sperm counts were dose-dependently decreased at 50 ug/kg EE2, whereas testicular sperm head counts were not different thancontrols. These results are similar to those previously demonstrated in EE2-treated male rats, and the presence of aneuploidic sperm at these concentrations is currently under evaluation. This abstract does not necessarily reflect US. EPA policy