UNDERNUTRITION DURING SUCKLING CHANGES THE SENSITIVITY TO HALOPERIDOLAND CHLORPROMAZINE IN 2 BEHAVIORAL MEASURES IN WEANING RATS

Undernutrition during critical periods of development may cause change s in the behavioural responses of rats to centrally acting drugs. In t he present study, the effects of undernutrition during suckling on the behavioural responses of 21-days-old rats to chlorpromazine (0, 2.5, 5, 10 and 20 mg/kg) or haloperidol (0, 0.125, 0.25, 0.5, 1 or 2 mg/kg) were examined. Locomotion was assessed at 1 hr 30 min., 4 hr 30 min., 7 hr 30 min. and 10 hr 30 min., and catalepsy was scored at 3 hr, 6 h r and 9 hr after drug administration. Drug was injected on two consecu tive days. On day 1, saline-treated undernourished rats showed signifi cantly greater locomotion activity than did normal rats. The neurolept ic-induced inhibition of locomotor activity in undernourished rats was significantly less than that observed in normal rats from 4 hr 30 min . to 10 hr 30 min. (chlorpromazine) or from 7 hr 30 min. to 10 hr 30 m in. (haloperidol). On day 2, a similar trend was observed but only in rats injected with 5 mg/kg chlorpromazine or 0.5, 1, and 2 mg/kg halop eridol. On day 1, the catalepsy scores at 3 hr revealed no significant difference between nutritional groups, but at 6 hr undernourished rat s responded significantly less to chlorpromazine or haloperidol. On da y 2, undernourished rats were less responsive to neuroleptics than nor mal rats, but the effect was not so evident as observed on day 1. The present results suggest that the behavioural effects of chlorpromazine and haloperidol are less persistent in undernourished rats, possibly due to differences in drug distribution and elimination, when compared to well-nourished rats.