Sigma 1 receptor subtype is involved in the relief of behavioral despair in the mouse forced swimming test

The immobility time in the mouse forced swimming test was dose-dependently reduced by sigma 1 receptor agonists, such as 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (SA4503) and (+)-pentazocine, and non-specific sigma receptor agonists, such as 1,3-di(2-tolyl)guanidine (DTG) and (+)-N-cyclopropyl-methyl-N-methyl-1,4-diphenyl-1-yl-but-3-en-1-ylamin e hydrochloride (JO-1784). On the other hand, pre-treatment with N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine monohydrochloride (NE-100), a putative sigma 1 receptor antagonist, completely antagonized the SA4503-, (+)-pentazocine- and DTG-induced reductions in immobility time. Such phenomena indicate that sigma receptor agonists alleviate behavioral despair. In addition, these antidepressive effects involve mainly the sigma 1 receptor subtype.