Reserpine-induced locomotor stimulation in mice chronically treated with typical and atypical antidepressants.

Previous studies have shown that chronic treatment with antidepressants (AD) leads to an increased responsiveness of NA systems to noradrenaline (NA) or its agonist. In the present paper the influence is described of a prolonged treatment with AD of different pharmacological profiles on the effect of reserpine in the first phase of its action (amine release). It has been found that in mice treated chronically (14 days, twice a day, i.p.) with imipramine, amitriptyline, maprotiline, (+)-oxaprotiline, zimelidine, citalopram, mianserin and iprindole, the injection of reserpine induces stimulation of the locomotor activity. Only (-)-oxaprotiline and fluvoxamine do not evoke this effect. AD given alone (both single and repeated doses), reserpine alone, AD in a single dose administered jointly with reserpine do not induce the locomotor stimulation. These results suggest that a prolonged treatment with AD increases the responsiveness of the dopamine (DA) mesolimbic system and/or the NA system.