Binding of imipramine to platelet membranes is lower in alcoholics than in controls.

The principal finding in this study was that imipramine binding to platelet membranes was lower in a group of ten alcoholics abstinent a mean of 11 days than in a group of ten age- and sex-matched controls (p less than 0.004). The mean (std dev, std error) for imipramine binding in the alcoholic subjects was 718 (110, 37) femtomol/mg platelet membrane protein and 931 (173, 58) femtomol/mg protein in the control subjects. Imipramine binding did not correlate significantly with age, severity of alcoholism, days of abstinence from alcohol, or severity of depression in the alcoholic subjects. Severity of depression did, however, correlate with severity of alcoholism (r = 0.678, p less than 0.03) in the alcoholic subjects in this study. The results of this preliminary experiment suggest that chronic ethanol exposure might affect either the synthesis of imipramine binding sites in megakaryocytes or the structural environment of imipramine binding sites in the platelet membrane. The significance of lower imipramine binding in alcoholics, all of whom expressed some depressive symptoms, remains to be established.