Serotonin, 5-hydroxyindoleacetic acid and serotonin transporter in blood peripheral lymphocytes of patients with generalized anxiety disorder

Abstract

Several immune system modifications have been reported in pathological anxiety, such as generalized anxiety, panic and obsessive-compulsive disorders. Since serotonin transporter is a marker of peripheral blood lymphocytes and it is modified in major depression, the aim of the present work was to evaluate this transporter by the binding of [ 3H]paroxetine to membrane preparations of blood peripheral lymphocytes from control subjects and patients with generalized anxiety disorder. The number of transporters and the affinity for the ligand did not differ among the two groups. Serotonin and 5-hydroxyindoleacetic acid (5HIAA) were determined in platelet-rich and -poor plasma, and in lymphocytes. Nonsignificant changes were found in the patients as compared to controls. However, there was a significant positive correlation between serotonin concentration in platelet-poor plasma and in lymphocytes in the patients, but not in the controls. This finding might be an indication of a poor regulation of the transporter function by which serotonin plasma concentration might influence lymphocyte serotonin concentration. Previous results indicate that serotonin transporter is reduced in these cells in major depression disorder; however, in generalized anxiety disorder, the number of transporters was not modified, although the functional efficiency of serotonin transporter might be altered.