Role of 5-HT 1A receptors in the forced swimming wheel test in reserpine-treated mice

Abstract

The antidepressant-like effect of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a selective 5-HT 1A receptor agonist, was studied in the forced swimming wheel test in reserpine-treated mice. 8-OH-DPAT and the antidepressant imipramine, dose-dependently increased the number of turns of a water wheel made by mice. This effect of imipramine (30 mg/kg, i.p.) was enhanced by reserpine treatment 24 hr before the test. The effect of 8-OH-DPAT (0.3 mg/kg, i.p.) was also enhanced in reserpine-treated mice. This enhanced effect of 8-OH-DPAT was blocked by pretreatment with the 5-HT 1A receptor antagonists, (−)-propranolol (3 mg/kg, i.p.) and NAN-190 (1 mg/kg, i.p.), but was not blocked by a β-blocker, (−)-atenolol (3 mg/kg, i.p.). 8-OH-DPAT did not affect locomotor activity in the reserpinized mice and did not affect the reduction of monoamine content induced by reserpine. These results suggest that the effect of 8-OH-DPAT in increasing the number of turns of the wheel made by mice was exerted through a 5-HT 1A receptor and that this effect did not reflect only changes in the locomotor activity of the mice.