Platelet alpha2 adrenoreceptors are decreased in number after antidepressant therapy

Abstract

1. 1. Specific binding of 3H-clonidine to alpha2 adrenoreceptors upon human blood platelet membranes is increased in patients with major depressive disorder (endogenous depression).2. 2. Specific binding of 3H-yohimbine to the platelet adrenoreceptor is not altered in endogenously depressed patients.3. 3. Other psychiatric disorders are not associated with alterations in the specific binding of either 3H-clonidine or 3H-yohimbine. In patients with severe congestive heart failure or with symptomatic coronary artery disease the number of platelet alpha2 adrenoreceptors is actually decreased.4. 4. Treatment of endogenously depressed patients with tricyclic antidepressants, lithium salts or electroconvulsive therapy results in a decrease in the number of alpha2 adrenoreceptors on blood platelet membranes.5. 5. These studies suggest that a supersensitivity of the alpha2 adrenoreceptor might exist in patients with endogenous depression and that effective forms of therapy lead to a decrease in the number of neural alpha2 adrenoreceptors which is reflected by a decrease in the number of these receptors upon blood platelet membranes.