Alpha 2-adrenergic receptor function in patients with unipolar and bipolar affective disorders.

Alpha 2-adrenergic receptor function was measured in platelets from unipolar (UP) depressed, bipolar (BP) depressed, and bipolar euthymic patients and normal control subjects. Only the platelets from UP depressed patients were different from control in having an increased number of alpha 2-receptors, a decreased percent norepinephrine inhibition of prostaglandin E1 (PGE1)-stimulated cyclic AMP (cAMP) production, and a decrease in PGE1 stimulation of cAMP production. Platelets from BP patients, depressed or euthymic, were not significantly different from control subjects. These preliminary data suggest that alpha 2-adrenergic receptor function and PGE1 stimulation of cAMP production are diminished in UP patients.