Dihydropyridine calcium channel antagonists as antidepressant drugs in mice and rats.

A pharmacological profile of the effects of nimodipine, nifedipine and nitrendipine (2.5-20 mg/kg p.o.) in several models which are indicative of possible antidepressant activity, was tested in mice and rats. These compounds, as well as verapamil (short-lasting effect), but not diltiazem, reduced the hypothermia induced by a large dose of apomorphine in mice. Nimodipine and nifedipine slightly increased the behavioural action of L-DOPA in mice, and nimodipine facilitated the action of imipramine in the L-DOPA test. Nimodipine, nifedipine, verapamil and diltiazem slightly reduced the clonidine-induced hypoactivity in rats. The hypothermia induced by reserpine or clonidine in mice was not changed by these drugs. Various antidepressants (imipramine, amitriptyline, citalopram, mianserin) used in the behavioural despair test in mice, in doses which were not effective by themselves, increased the immobility-reducing effect when given jointly with 1,4-dihydropyridine calcium channel antagonists (5 mg/kg). The above results indicate that the psychopharmacological profile of nimodipine, nifedipine and nitrendipine resembles that of antidepressants in some tests only; moreover, these results support the assumption that concomitant administration of antidepressants and 1,4-dihydropyridine calcium channel antagonists may result in a greater antidepressant efficacy.