Increased Serum Tropomyosin-related Kinase B Protein Level in Obese Patients with Major Depressive Disorder

Abstract

Objectives: Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) protein have been previously associated with mood disorders. Here, we aimed to investigate the roles of BDNF and TrkB in suicidality and obesity in patients with major depressive disorder (MDD). Methods: The serum protein levels of BDNF and TrkB were determined in 60 MDD in-and outpatients. We classified men and women with a body mass index (BMI) of ≧26.4 kg/m^2 as obese. We examined the differences in serum BDNF and TrkB protein levels between obese/non-obese and suicidal/non-suicidal MDD patients. Results: We found no significant difference in serum BDNF protein levels between obese and non-obese MDD patients or between MDD patients with or without suicide history. The TrkB protein levels were found to be significantly increased in obese MDD patients compared with those in non-obese MDD patients (F=4.137, p=0.047), but no significant difference was found in the TrkB protein levels between MDD patients with and without suicide history. Conclusion: We found in this study that obesity in our study MDD patients was associated with increased serum TrkB levels. Increased TrkB levels may play a role in the pathophysiology of obese MDD patients.