Strain comparisons of atrazine-induced pregnancy loss in the rat

Atrazine was administered by gavage, in Ile methylcellulose, to F344 Spragu e-Dawley (SD), and Long Evans (LE) rats at 0, 25, 50, 100, or 200 mg/kg/day on gestation days 6 through 10. The dams were allowed to deliver and litte rs were examined postnatally. The F344 strain was the most sensitive to atr azine's effects on pregnancy, showing full-litter resorption (FLR) at great er than or equal to 50 mg/kg. In surviving F344 litters, prenatal loss was increased at 200 mg/kg. In SD and LE rats, FLR occurred only at 200 mg/kg. Delayed parturition was seen at greater than or equal to 100 mg/kg in F344 and SD rats. Regarding maternal toxicity, the SD dams were the most sensiti ve, with weight loss at greater than or equal to 25 mg/kg. When 200 mg/kg w as administered to F344 rats on days 11 through 15 (after the LH-dependent period of pregnancy), no FLR was seen. These findings suggest that atrazine -induced FLR is maternally mediated, and consistent with loss of LH support of the corpora lutea. (C) 2001 Elsevier Science Inc. All rights reserved.