Platelet 5-HT uptake sites in depression: three concurrent measures using [3H] imipramine and [3H] paroxetine

Platelet 5-HT uptake sites were measured in 40 depressed patients and 40 controls using ³H] imipramine binding, defined with desmethylimipramine (DMI) and Na⁺ dependence, and ³H] paroxetine binding. In control subjects the B_max of DMI defined ³H] imipramine binding was significantly higher than both Na⁺ dependent ³H] imipramine (by 30%) and ³H] paroxetine binding (by 22%). The B_max of Na⁺ dependent ³H] imipramine and ³H] paroxetine binding did not differ significantly. The K_d of Na⁺ dependent ³H] imipramine binding was significantly lower than the K_d of DMI defined ³H] imipramine binding. The binding of DMI defined and Na⁺ dependent ³H] imipramine and ³H] 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 with-drawn from antidepressants. This study provides no support for the view that the number of platelet 5-HT uptake sites are reduced in depression.