You are here:
ADVERSE EFFECTS OF PRENATAL EXPOSURE TO ATRAZINE DURING A CRITICAL PERIOD OF MAMMARY GLAND GROWTH
Citation:
Rayner, J. L., R. R. Enoch, AND S E. Fenton. ADVERSE EFFECTS OF PRENATAL EXPOSURE TO ATRAZINE DURING A CRITICAL PERIOD OF MAMMARY GLAND GROWTH. TOXICOLOGICAL SCIENCES 87(1):255-266, (2005).
Impact/Purpose:
To determine if the fetal mammary gland is sensitive to atrazine effects during specific periods of development
Description:
Prenatal exposure to 100 mg/kg atrazine (ATR) was previously shown to delay mammary gland (MG) development in the female offspring of Long Evans (LE) rats. To determine if the fetal MG was most sensitive to ATR effects during specific periods of development, timed-pregnant dams (N=8/group) were dosed for 3 or 7-day intervals during gestation (GD 13-15, 15-17, 17-19, or 13-19) with 100 mg ATR/kg/d or vehicle controls (C), and their offspring evaluated for endocrine, puberty, reproductive tissue, body weight (BW) and MG changes. MG taken from pups exposed to ATR on GD15-17, 17-19, and 13-19 (N>4 dams/group) as early as PND4 displayed significant delays in epithelial development compared to C, and all exposed MG were smaller in area regardless of BW. MG from animals in these groups and the GD13-15 group were also developmentally delayed at later time points when compared to C. However, the most persistent and severe delays were seen in the GD17-19 and GD13-19 ATR exposure groups, and the 3 d and 7 d exposures demonstrated statistically similar growth retardation. Due to persistent MG developmental deficits in sexually mature offspring, we hypothesized that ATR-exposed animals may have difficulties nursing their young. Females exposed in utero to either ATR (groups defined above) or C (N>4 in separate litters/group) were bred and allowed to rear their offspring. The F2 offspring from GD17-19 and GD13-19 prenatal exposure groups were significantly smaller in BW than C, and F2 females exhibited underdeveloped MG due to lower BW at PNDs 4 and 11. However, in a separate study, it was determined that ATR (8.7 to 100 mg/kg), delivered from GD 15-19, did not decrease fetal body weights on GD20, even though the higher dosed cause significant lack of weight gain by the dosed dams. Taken together, these data suggest that the consequences of short prenatal ATR exposure during what seems to be a critical period of fetal mammary development (GD 17-19) can not only delay mammary development of the offspring, but can also lead to inadequate nutritional support of offspring in the next generation, resulting in adverse effects on pup weight gain.