Higher serum tropomyosin-related kinase B protein level in major depression.

Accumulating evidence suggests that the brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) are molecules involved in the pathophysiology of major depressive disorder and response of antidepressants. To examine both BDNF and TrkB protein levels and their relationship with psychopathology in patients with major depressive disorder, 55 physically healthy patients with major depressive disorder were compared with 53 healthy controls. The severity of major depression was assessed by the 17-item Hamilton Depression Rating Scale (HDRS). Serum BDNF and TrkB protein levels were measured with Enzyme-linked immunosorbent assay (ELISA) kits. After using the analysis of covariance (ANCOVA) with age adjustment, the results of this work showed that BDNF presented no significant difference (F(1,107)=0.149, p=0.701) but the TrkB protein level was significantly higher in depressive patients than in healthy controls (F(1,107)=4.043, p=0.047). These findings suggest that the serum TrkB protein level may play an important role in the psychopathology of major depression.