INFLUENCE OF MATERNAL STRESS ON THE EFFECTS OF PRENATAL EXPOSURE TO METHYLMERCURY AND ARSENIC ON POSTNATAL-DEVELOPMENT AND BEHAVIOR IN MICE- A PRELIMINARY EVALUATION

The present study combined maternal restraint stress with exposure to 2 environmental toxic elements, mercury and arsenic, given to mice con currently with the restraint period (1000-1200 h, gestational days 15- 18). Two groups of animals were given, by gavage, methylmercury chlori de (MMC) (2 mg/kg/day), and 2 additional groups received sodium arseni te (10 mg/kg/day) on days 15-18 of gestation. Immediately after MMC or arsenite exposure, 1 group of MMC-treated mice and 1 group of arsenit e-treated animals were restrained for 2 h/day. Control groups included restrained and unrestrained pregnant mice nonexposed to MMC or arseni te. All animals were allowed to deliver and wean their offspring. Pups were evaluated for physical development, as well as for behavioral ef fects. Except for a significant decrease in pivoting on postnatal day 9 in the group exposed to arsenite plus restraint, no other MMC- or ar senite-induced behavioral changes were noted in unrestrained or restra ined groups. Although a significant delay in pinna detachment and in e ye opening was observed in pups of the group exposed to arsenite and r estraint, the developmental landmarks were not affected by restraint i n the MMC-treated animals. Although maternal stress reduced body weigh t gain in the dams exposed to MMC plus restraint, a significant intera ction between maternal stress and MMC could not be established for dev elopmental toxicity. These preliminary results, combined with those of previous investigations, show that stress can significantly exacerbat e the adverse effects of environmental toxic elements. (C) 1997 Elsevi er Science Inc.