The effect of chronic lithium administration and withdrawal on locomotor activity and apomorphine-induced locomotor stimulation in rats.

The effect of chronic lithium administration and withdrawal on locomotor activity and apomorphine-induced locomotor stimulation in rats was studied. Chronic lithium administration caused a decrease in locomotor activity, which might be due to a lithium-induced decrease of exploratory behaviour. Chronic lithium administration had no effect on apomorphine-induced locomotor stimulation. However, apomorphine-induced locomotor stimulation was increased two days after the withdrawal of lithium while no difference was found after four days, suggesting a transient increase in postsynaptic dopamine (DA) receptor sensitivity following lithium withdrawal.