Prenatal and postnatal chronic lead intoxication and running wheel activity in the rat

Prenatal and postnatal chronic lead intoxication was induced in Wistar rats with 0.1 mg/ml PbCl2 in the drinking water of pregnant and lactating females. Offspring were supplied lead water at weaning. Exposure totaled 14 months. Activity was measured in the Wahman LC-33 wheel. Running activity in experimental and control rats was maximized with a 23-hr light cycle followed by a 5-hr dark period in the wheels. There was no significant difference in body weight gains or lead intake (as measured by water consumption) between any sex-matched group. Lead was found to produce overall hypoactivity in both males and females. Under auditory stress the hypoactivity in the males was normalized by combination of a hypoactivity component in the controls and a progressive hyperactivity in the lead animals. This study clearly shows a sex-dependent hypoactivity effect of chronic lead intoxication and suggests its mechanism as an interaction between lead and environmental stress.