Platelet Tritiated Imipramine Binding and Serotonin Uptake in Depressed Patients and Controls: Relationship to Plasma Cortisol Levels Before and After Dexamethasone Administration

We measured platelet tritiated imipramine binding and serotonin uptake in 51 depressed patients and 43 normal controls. Although there were no significant differences in platelet ³H-imipramine binding or serotonin uptake when the total group of depressed patients was compared with controls, depressed women (n = 32) had a significantly lower maximal density of ³H-imipramine binding sites (β_max) than control women (n = 25). Moreover, among the total group of depressed patients, there were significant negative correlations between the β_maxvalues and plasma cortisol levels at 4 PM (n = 41) and 11 PM (n = 41) following dexamethasone administration. These negative correlations between β_maxand cortisol levels were strongest among melancholic patients both at 4 PM before dexamethasone administration (n =14) and at 11 PM after dexamethasone administration (n =15). These data suggest that the reported decrease in β_maxfound among depressed patients may be related to and is perhaps secondary to the hypercortisolemia of depression.