The clinical and research significance of reduced imipramine binding has remained unclear despite considerable investigation. This study used an assay of demonstrated reliability to investigate the clinical correlates of imipramine binding to platelets in 63 depressed and 33 nondepressed psychiatric patients and 40 healthy control subjects. Both patient groups had Bmax values significantly lower than those of the healthy controls. Unequivocal associations between binding parameters and individual symptoms or groups of symptoms were not established, but a negative correlation between Kd and the number of adverse life events experienced in the preceding 6 months was apparent. These findings provide no support for the view that reduced binding is a trait marker for susceptibility to depression and cast doubt on its specificity as a state marker for the syndrome of depression.

The binding characteristics of platelet alpha 2-adrenoceptors, lymphocyte beta 2-adrenoceptors and platelet imipramine receptors were studied in five women during their menstrual cycle. A significant cyclic variation in the number of beta 2-adrenoceptor sites on intact lymphocytes was found during the menstrual cycle, while binding to alpha 2-adrenoceptors and imipramine receptors remained unchanged.