ENHANCED DISPLACEMENT OF [H-3]IMIPRAMINE, BUT NOT [H-3]PAROXETINE BINDING BY PLASMA FROM DEPRESSED-PATIENTS

Plasma from healthy subjects inhibited the binding of [H-3]imipramine competitively and [H-3]paroxetine non-competitively to platelet membra nes in a volume-dependent manner. Plasma from 40 depressed patients wa s more effective at inhibiting [H-3]imipramine, but not [H-3]paroxetin e, binding compared to plasma from matched controls. This difference w as not related to recent antidepressant treatment. The results suggest that the concentration of an endogenous modulator of [H-3]imipramine binding is increased in depressive illness. The concentration of alpha (1)-acid glycoprotein, a proposed endogenous modulator of [H-3]imipram ine binding, did not differ between depressed patients and cont-ols. O ur results suggest that factors other than alpha(1)-acid glycoprotein may modulate [H-3]imipramine binding. (C) 1997 Elsevier Science B.V.