Biogenic amines and the effect of short term lithium administration on open field activity in rats

Experiments were performed to examine whether the effects of short-term lithium administration on cerebral biogenic amine metabolism might be related to its action on open field activity. Rats received intragastric injections of lithium chloride (1.5 mEq/kg) twice daily for 5 days. This lead to a decrease in exploratory behavior in the open field. Administration of imipramine, which blocks the efffects of short-term lithium administration on norepinephrine turnover and uptake in the brain, failed to influence the effect of lithium on exploratory activity. Parachlorophenylalanine, which inhibits cerebral serotonin synthesis and depletes brain catecholamines, prevented the behavioral effect of lithium. Injection of pargyline, which inhibits cerebral monoamine oxidase activity, counteracted the effect of lithium on exploratory behavior and also influenced the emotionality of the animals in the open field. The findings are consistent with the hypothesis that cerebral monoamine levels and monoamine oxidase activity play a role in the effect of short-term lithium administration on open field activity in rats.