ROLE OF 5-HT(1A) RECEPTORS IN THE FORCED SWIMMING WHEEL TEST IN RESERPINE-TREATED MICE

The antidepressant-like effect of 8-hydroxy-2-(di-n-propylamino)tetral in(8-OH-DPAT), a selective 5-HT1A receptor agonist, was studied in the forced swimming wheel test in reserpine-treated mice. 8-OH-DPAT and t he 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. Th e effect of 8-OH-DPAT(0.3 mg/kg,i.p.) was also enhanced in reserpine-t reated mice. This enhanced effect of 8-OH-DPAT was blocked by pretreat ment with the 5-HT1A) receptor antagonists, (-)-propranolol(3 mg/kg,i. p. and NAN-190(1 mg/kg,i.p.), but was not blocked by a beta-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 monoamin e 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 mi ce was exerted through a 5-HT1A receptor and that this effect did not reflect only changes in the locomotor activity of the mice.