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LATE GESTATIONAL ATRAZINE EXPOSURE DECREASES MATERNAL BEHAVIOR IN LONG-EVANS RATS
Citation:
Rayner, J. L. AND S E. Fenton. LATE GESTATIONAL ATRAZINE EXPOSURE DECREASES MATERNAL BEHAVIOR IN LONG-EVANS RATS. Presented at Society of Toxicology, New Orleans, LA, March 6-10, 2005.
Description:
Late Gestational Atrazine Exposure Alters Maternal Nursing Behavior in Rats
Jennifer L. Rayner1 and Suzanne E. Fenton2
1 University of North Carolina at Chapel Hill, DESE, Chapel Hill, NC, and 2 USEPA/ ORD/NHEERL/Reproductive Toxicology Division, RTP, NC.
Atrazine, ATR, is a widely used herbicide shown to delay early mammary development and reduce body weight in female offspring of exposed Long Evans (LE) rat dams. To determine if ATR affects maternal behavior, dams were gestationally dosed and evaluated following parturition. Timed-pregnant LE rats were gavaged gestational days (GD)17-19, 15-19, or 13-19 with 100 mg ATR/kg body weight (BW), an environmentally based mixture (EBM) of ATR and its metabolites (8.7 mg/kg total, 25% ATR) GD13-19, or vehicle (controls, C) GD13-19 (these treatments shown to have no effect on fetal weight). Pup BW was recorded on postnatal days (PND) 4 and 11 (analyzed by litter). By PND 4, female pup BW in ATR GD17-19 and 13-19 groups were decreased from control (p<0.001), and male pup BW in EBM, and ATR GD17-19 and 13-19 groups were decreased from control (p<0.02), leading us to believe there may be an effect of ATR on lactation. To assess maternal nursing behavior on PND 11, dams were removed from their litters for 3 hours to allow for milk accumulation. Pups were weighed immediately before dams were placed back with their litters. Pups in all groups were allowed to suckle for 30 consecutive minutes and then removed from their dam for weighing. Dams were sacrificed immediately. Maternal behavior was defined as crouching on litters for nursing, in an arched-back position. There was a significant effect of treatment on this maternal behavior, (p<0.001). Dams exposed to 100 mg/kg ATR GD17-19 and 15-19 took more than 2- and 3-fold longer to nest upon their litters, respectively, than control dams (p<0.005). Female pup BW in the ATR GD13-19 group was still decreased from control, p<0.001 pre-suckling, p<0.02 post-suckling. These results show that brief gestational exposures to ATR can alter maternal behavior specifically related to nursing. (This abstract is of a proposed presentation and does not reflect EPA policy; Supported by NHEERL-DESE, EPA CT826513.)