Postnatal cadmium exposure and longterm behavioral changes in the rat.

Although cadmium is a well known toxicant, its effects at subtoxic doses on behavior have rarely been investigated. The present study examined the longterm effect on levels of spontaneous locomotor activity and performance in a learning task resulting from postnatal exposure to cadmium. Sixty-four male Sprague-Dawley rat pups were divided into seven treatment and one vehicle control group. Treated animals were intubated with CdCl2 from the sixth to fifteenth day of life at doses ranging from 0.25 to 7.0 mg/kg body weight. Activity was quantified in tilt cages at forty-five days of age and performance in an appetitively motivated spatial discrimination task, with reversal, was assessed at between ninety and ninety-four days of age in a T-maze. A significant increase in spontaneous locomotor activity was observed in rats treated with 0.25 mg/kg of cadmium. In general, cadmium treated animals performed better than control subjects during learning and reversal learning trials. Possible hypotheses accounting for these results are discussed.