G-protein level quantification in platelets and leukocytes from patients with panic disorder

The objective of our study was to investigate if there are abnormalities in signal transducing G proteins in patients with panic disorder. We utilized selective antibodies to quantitate the levels of the G protein alpha subunits that regulate adenylyl cyclase activity (G alpha s and G alpha i2) and phosphoinositide turnover (G alpha q/11) in platelet membranes (and leukocyte membranes for G alpha s), and also carried out pertussis toxin (PT) catalyzed [32P]ADP-ribosylation in platelet membranes from a group of 13 untreated panic disorder patients, 10 untreated social phobia patients, and 12 healthy subjects. There were no significant differences among the three groups in the immunolabeling of G alpha s in platelets or leukocytes, or in the immunolabeling of G alpha i1/2, G alpha q/11, or PT-catalyzed [32P]ADP-ribosylation in platelets. Within the constraints imposed by using peripheral blood cells to reflect brain composition, our results do not provide support for G protein abnormalities in patients with panic disorder. These results contrast with those obtained using identical methodology in bipolar affective disorder, where elevated G alpha s in leukocytes has been reported (Manji et al. 1995).