Platelet α2-adrenergic receptor coupling efficiency to Gi protein in subjects with post-traumatic stress disorder and normal controls

Abstract

Low platelet membrane α₂-adrenergic receptor (α₂AR) density and low basal and forskolin-stimulated cyclic adenosine monophosphate responses, which have been reported in post-traumatic stress disorder (PTSD), suggest either abnormal α₂AR coupling to G_i protein or dysregulation in post-receptor signal transduction mechanisms. α₂AR density in the high- and low-conformational states, agonist affinity in both states and coupling to G_i protein were investigated in 23 drug-free combat PTSD patients and 25 normal controls. α₂AR coupling measures were not different between PTSD patients and controls. Total α₂AR density was higher in PTSD patients than controls, due to a higher density of the receptor in the high-conformational state. There were no differences in agonist affinity to the receptor in either conformational state. Results rule out dysregulation in α₂AR coupling to G_i protein. Studies of post-receptor signal transduction mechanisms are warranted.