Role of brain regional GABA: aldrin-induced stimulation of locomotor activity in rat.

Aldrin, a chlorinated hydrocarbon group of pesticide, is a well known central nervous system (CNS) stimulant. The CNS stimulating effect of aldrin is manifested in the form of an increase in locomotor activity (LA) of animals. Maximum increase in LA was observed at 2 h following aldrin (2-10 mg/kg, p.o.) treatment and this aldrin-induced increase in LA attained a peak at a dose of 10 mg/kg, p.o. Administration of aldrin (2 or 5 mg/kg/day, p.o.) enhanced LA of rats and reached a maxima after 12 consecutive days of treatment following which aldrin-induced LA was gradually reduced and restored to control value after 20 consecutive days of aldrin treatment. A single administration of aldrin (2-10 mg/kg, p.o.) reduced the GABA system in cerebellum, hypothalamus and pons-medulla. The treatment with aldrin (2 mg/kg/day, p.o.) for 12 consecutive days produced more inhibition in those brain regional GABA system than that observed with a single dose of aldrin. These results, thus, suggest that aldrin-induced inhibition of central GABA may be a cause of stimulation of LA with aldrin either at a single dose or for 12 consecutive days.