Offspring open field performance following maternal lead exposure: a question of dosage and nutritional status.

Although a number of experiments has revealed offspring hyperactivity following maternal lead (Pb) exposure, a consistent correlate has been reduced pup size. The present study was designed to measure exploratory behavior employing a range of Pb dosages that allowed for the comparison between Pb and control offspring both in the presence and the absence of weight differences. Female rats were exposed to one of four dosages (0, 400, 750 or 1000 mg/kg) of Pb acetate from 21--90 days of age, mated and then continued on treatment throughout gestation and nursing. Treatment was administered via a restricted water schedule. Open field testing began on Day 22 with the pups receiving 3 min trials for 10 consecutive nights. At 120 days of age, all pups were retested. Analysis indicated that only in the presence of reduced birth and/or weaning weights (Groups 750 and 1000) did offspring exhibit exploratory patterns that were significantly different from controls. These differences were absent at retest.