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INFLUENCE OF THE DRINKING WATER DISINFECTION BY-PRODUCT DIBROMOACETIC ACID ON RAT ESTROUS CYCLICITY AND OVARIAN FOLLICULAR STEROID RELEASE IN VITRO
Citation:
Balchak, S. K., J M. Hedge, A. E. Shearin, M L. Mole, AND J M. Goldman. INFLUENCE OF THE DRINKING WATER DISINFECTION BY-PRODUCT DIBROMOACETIC ACID ON RAT ESTROUS CYCLICITY AND OVARIAN FOLLICULAR STEROID RELEASE IN VITRO. REPRODUCTIVE TOXICOLOGY. Elsevier Science BV, Amsterdam, Netherlands, 14(6):533-539, (2000).
Description:
The drinking water disinfection by-product, dibromoacetic acid (DBA) has been reported to affect gonadal functions in the male rat. However, there is little information regarding its influence on female reproductive activity. Consequently, the present study investigated the effects of DBA on estrous cyclicity and its impact in vitro on ovarian follicular steroid secretion. Regularly cycling animals were dosed with DBA (0 - 270 mg/kg/d) for 14 days and estrous cyclicity monitored during treatment and for an additional 2 week post-treatment interval. A dose-related alteration in cyclicity was observed at 90 and 270 mg/kg, which persisted through the post-treatment monitoring in the high dose group. An in vitro exposure of preovulatory follicles to DBA was then used to assess the influence of DBA on steroid release. To select a concentration for use, a single oral exposure to 270 mg/kg was administered, and the mean blood levels were determined over a 5 hour interval. For this in vitro work, pairs of preovulatory follicles from PMSG-primed immature rats were exposed to 0 or 50 mg/ml DBA over a 24-hour period and evaluated for estradiol and progesterone release under baseline and hCG-stimulated conditions. The influence of tumor necrosis factor-a (TNFa) exposures under these conditions was also determined. In the non-stimulated condition, DBA was found to increase the release of estradiol, but had no detectable effect in response to hCG. Progesterone, however, showed a marked suppression under hCG stimulation following exposure to DBA, while non-stimulated secretion was unaffected. TNFa by itself also suppressed stimulated progesterone release, but had no additional effect in combination with DBA. The data suggest that one factor in the disruption in estrous cyclicity could be an alteration in steroid production, which was characterized by separate effects on both estradiol and progesterone secretion.