PLATELET 5-HT UPTAKE SITES IN DEPRESSION - 3 CONCURRENT MEASURES USING [H-3] IMIPRAMINE AND [H-3] PAROXETINE

Platelet 5-HT uptake sites were measured in 40 depressed patients and 40 controls using [H-3] imipramine binding, defined with desmethylimipramine (DMI) and Na+ dependence, and [H-3] paroxetine binding. In control subjects the B(max) of DMI defined [H-3] imipramine binding was significantly higher than both Na+ dependent [H-3] imipramine (by 30%) and [H-3] paroxetine binding (by 22%). The B(max) of Na+ dependent [H-3] imipramine and [H-3] paroxetine binding did not differ significantly. The K(d) of Na+ dependent [H-3] imipramine binding was significantly lower than the K(d) of DMI defined [H-3] imipramine binding. The binding of DMI defined and Na+ dependent [H-3] imipramine and [H-3] paroxetine did not differ significantly between depressed patients and controls in the total group, in those depressed patients who had never taken antidepressants or in those depressed patients who had been recently withdrawn from antidepressants. This study provides no support for the view that the number of platelet 5-HT uptake sites are reduced in depression.