The effect of lithium on the locomotor stimulation induced by dependence-producing drugs.

The present study was performed to investigate how lithium affects locomotor stimulation induced by dependence-producing drugs such as amphetamine, ethanol and morphine. Acute lithium alone was found to suppress exploratory hyperactivity in mice without affecting basal locomotor activity, further supporting the contention that lithium has a neurolept-like behavioural profile. Acute lithium pretreatment suppressed locomotor stimulation in mice induced by all the dependence-producing drugs in a dose-dependent manner. Locomotor stimulation seen after amphetamine and ethanol appeared to be more suppressed by lithium than that seen after morphine. Taken together with the finding that lithium had no effect on apomorphine-clonidine-induced locomotor stimulation after elimination of presynaptic activity the present data suggest that the suppressive effect of lithium is mediated via presynaptic catecholaminergic mechanisms.