POSTNATAL-DEVELOPMENT AND BEHAVIOR OF WISTAR RATS AFTER PRENATAL TOLUENE EXPOSURE

Pregnant Wistar rats were treated with different concentrations of tol uene by inhalation (300: 600, 1000 and 1200 ppm) from day 9 to day 21 of pregnancy for 6 h a day in a whole-body inhalation chamber (control s inhaled fresh air only). From day 22, rats were kept single-caged an d were allowed to deliver. Besides a detailed evaluation of the physic al development of the offspring we performed the following tests: fore limb-grasp reflex, righting reflex, cliff-drop aversion reflex, mainta inance of balance on a rotating rod, measurement of locomotor activity and learning ability in a discrimination learning test. A toluene exp osure of 1200 ppm resulted in a reduced body weight of rat dams and of fspring and a higher mortality until weaning. The physical development (incisor eruption, eye opening and vaginal opening) was retarded in t his group. There were no clear-cut and concentration-dependent differe nces in the development of reflexes, rota rod performance and locomoto r activity between the offspring of animals exposed to toluene and the controls. Likewise, no effects were found on learning ability in the operant conditioning task. Compared to the controls there were no diff erences in mating, fertility and pregnancy indexes in the F-1-generati on. The tests performed have provided no evidence that toluene exposur es less than or equal to 1200 ppm induce adverse effects on the behavi our of rat offspring exposed during late embryonic and fetal developme nt.