[3H-Imipramine binding to human platelets. A peripheral index in depressive syndromes (author's transl)].

3H-imipramine shows specific, high-affinity binding to human platelet sites. The characteristics of these specific binding sites are very similar to those previously described in the rat brain. The inhibitory effects of 11 tricyclic antidepressants on 3H-imipramine binding to human platelets were investigated. There was a significant correlation between the inhibition observed and the average therapeutic doses of antidepressants, which suggests that the binding sites may be involved in the mode of action of these drugs. The number of binding sites (Bmax) for 3H-imipramine was compared in 39 controls and in 37 hospital patients with untreated severe depressive syndrome and was found to be significantly smaller in depressed patients, without any modification of the affinity constant Kd. The significance of these findings and their changes under treatment are discussed.