Chronic imipramine administration reduces apomorphine inhibitory effects.

Changes in activity of dopaminergic and serotonergic systems were assessed after acute and chronic (14 days) imipramine (10 mg/kg) administration in mice. For this purpose, biochemical and behavioural tests were performed at different intervals of time after withdrawal of treatment. Brain levels of 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, homovanillic acid and 3,4-dihydroxyphenylacetic acid were assayed by a fluorometric method. Locomotion and stationary behaviour were investigated in the open-field test. The results of the experiments suggest that chronic imipramine reduces the inhibitory effects of apomorphine upon the dopaminergic system.