Lead-induced behavioral disorders in the rat: effects of amphetamine.

The effects of d-amphetamine on several measures of activity and spontaneous alternation were evaluated in rats chronically exposed to a low level of lead acetate via maternal milk during the neonatal period. Alterations in the amphetamine responses of lead-treated rats were observed with some measures of activity and exploration but not with others. 'Paradoxical' responses were observed with postural rearing and spontaneous alternation. No drug response was seen in lead-treated animals with respect to center field activity in contrast to a large increase seen in controls. Normally, amphetamine reduces grooming behavior, but since this reduction was greater in lead-reared than in control rats, the data suggest that for this measure the lead-reared rat may posses an increased sensitivity to amphetamines. These results were discussed in terms of the behavioral parallels found between lead poisoning and childhood hyperactivity, and the potential of this model as an animal analog of minimal brain dysfunction hyperactivity.