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PREGNANCY LOSS IN THE RAT CAUSED BY BROMODICHLOROMETHANE
Citation:
Bielmeier, S. R., D S. Best, D. L. Guidici, AND M G. Narotsky. PREGNANCY LOSS IN THE RAT CAUSED BY BROMODICHLOROMETHANE. TOXICOLOGICAL SCIENCES 59(2):309-315, (2001).
Description:
Bromodichloromethane (BDCM), a trihalomethane, is a by-product of the chlorination of drinking water. In a recent epidemiological study, consumption of BDCM was associated with an increased risk of spontaneous abortion in pregnant women. We have previously shown that bromodichloromethane (BDCM) causes pregnancy loss, i.e. full-litter resorption (FLR), in the F344 rat. The mode of action was investigated, with three main findings. First, there was a dramatic difference in sensitivity between F344 and Sprague Dawley (SD) strains. Following aqueous gavage treatment on gestational days (GD) 6-10, F344 rats had a 62% incidence of FLR at 75 mg/kg/day, whereas all SD rats maintained their litters. Second, the critical period encompassed the luteinizing hormone (LH)-dependent period of pregnancy. Rats treated on GD 6-10 at 75 mg/kg/day had a 75% incidence of FLR, but rats treated on GD 11-15 at 75 or 100 mg/kg/day were unaffected. Third, 24 hours after a single dose, all dams with FLR had markedly reduced serum progesterone levels; however, LH levels were unaffected. The high FLR rate during the LH-dependent period, the lack of response thereafter, and the reduced progesterone levels without an associated reduction in LH levels suggests BDCM disrupts luteal responsiveness to LH.