Platelet alpha-2-receptor binding and adenylate cyclase activity in panic disorder

Abstract

The function of the alpha-2-receptor and intracellular effector systems was examined in 39 panic disorder patients and 30 healthy subjects using the platelet as a model system. Alpha-2-receptor density, as reflected by ³H-yohimbine binding, was not different between the two groups. Platelet alpha-2-receptor affinity was decreased (higher K_d) in the panic disorder patients. Other significant abnormalities in the patients included a decreased basal adenylate cyclase activity, reduced EC₅₀ for the epinephrine inhibition of adenylate cyclase activity, and decreased stimulation of adenylate cyclase activity by prostaglandin E₁ and sodium fluoride. These results are consistent with a dysfunction in some panic disorder patients at the level of the stimulatory GTP binding regulatory protein, G_s, or the adenylate cyclase catalytic unit. The relationship of these findings to previous studies of noradrenergic function in panic disorder patients is discussed.