Platelet alpha 2 adrenoreceptors are decreased in number after antidepressant therapy.
Specific binding of 3H-clonidine to alpha 2 adrenoreceptors upon human blood platelet membranes is increased in patients with major depressive disorder (endogenous depression). Specific binding of 3H-yohimbine to the platelet adrenoreceptor is not altered in endogenously depressed patients. 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 alpha 2 adrenoreceptors is actually decreased. Treatment of endogenously depressed patients with tricyclic antidepressants, lithium salts or electroconvulsive therapy results in a decrease in the number of alpha 2 adrenoreceptors on blood platelet membranes. These studies suggest that a supersensitivity of the alpha 2 adrenoreceptor might exist in patients with endogenous depression and that effective forms of therapy lead to a decrease in the number of neural alpha 2 adrenoreceptors which is reflected by a decrease in the number of these receptors upon blood platelet membranes.
D000818:Animals; D000928:Antidepressive Agents / Q000627:therapeutic use*; D000929:Antidepressive Agents, Tricyclic / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D001921:Brain / Q000187:drug effects; D003000:Clonidine / Q000097:blood; D003866:Depressive Disorder / Q000097:blood / Q000188:drug therapy*; D004565:Electroconvulsive Therapy; D006801:Humans; D007700:Kinetics; D008094:Lithium / Q000627:therapeutic use; D016651:Lithium Carbonate; D009638:Norepinephrine / Q000378:metabolism; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D015016:Yohimbine / Q000097:blood
D000928:Antidepressive Agents; D000929:Antidepressive Agents, Tricyclic; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D016651:Lithium Carbonate; D015016:Yohimbine; D008094:Lithium; D003000:Clonidine; D009638:Norepinephrine