Voluntary activity in the aging rat as a function of maternal drug exposure

Sixty-eight Sprague-Dawley derived primiparous rats were injected subcutaneously twice daily throughout pregnancy and the nursing period with either (1) 3.0 mg/kg of pure nicotine, (2) 5.0 mg/kg methamphetamine HCl, or (3) saline vehicle. Locomotor activity was monitored one night/month from 3-39 months of age in randomly selected male offspring. Significant differences in activity levels were found as a function of maternal treatment for 29 of 35 sessions. The contrasts revealed that methamphetamine offspring were the most active group and there was no shift in relative group positions over time. There was some evidence for periodic activity changes at 5, 6, and 12 month intervals. A trend test revealed a significant decline in activity in the 12 month period preceding death which was not drug-related but common to all groups. Theoretical implications are discussed.