Effects of 5-HT2 receptor antagonists on the anti-immobility effects of imipramine in the forced swimming test with mice

The effects of 5-HT2 receptor antagonists on antidepressant effects of imip ramine were investigated in the forced swimming test. Imipramine induced an ti-immobility effects in mice dose dependently. Pretreatment with the 5-HT2 A/2B/2C receptor antagonist, 4-isopropyl-7-methyl-9-(2-hydroxy-1-methyl-pro poxycarbonyl)-4,6A,7,8,9,10,10A-octahydro-indolo[4,3-FG]quinolone maleate ( LY 53857) significantly enhanced the anti-immobility effects of imipramine. The 5-HT2C/2B receptor antagonist, N-3-pyridinyl-3,5-dihydro-5-methyl-benz o[1,2-b:4,5-b']dipyrrole-1(2H)-carboxamide (SB 206553), also enhanced, whil e the 5-HT2A receptor antagonist, ketanserin, was without effect. These res ults suggest that blockade of the 5-HT2C/2B receptor leads to potentiation of the antidepressant effects of imipramine, (C) 2001 Elsevier Science B.V. All rights reserved.