The relationship between brain-derived neurotrophic factor levels, oxidative and nitrosative stress and depressive symptoms: a study on peritoneal dialysis

Abstract

Background: Depression is one of the most commonly encountered psychiatric problems in peritoneal dialysis (PD) patients. Our aim was to investigate the associations between oxidative and nitrosative stress (O&NS) and brain-derived neurotrophic factor (BDNF) in PD patients with elevated depressive symptoms (EDS). Methods: Eighty-three patients with PD and 84 healthy controls were enrolled in this study. In PD patients, two subgroups were formed: 28 with and 55 without EDS. EDS were defined as a Beck Depression Inventory (BDI) score ≥17 in patients. Serum malondialdehyde (MDA) erythrocyte, glutathione (GSH) levels measured spectrophotometrically. Serum superoxide dismutase (SOD) activity, nitric oxide (NO) and BDNF levels were determined by ELISA. Results: While MDA and NO levels were higher, levels of SOD, GSH and BDNF were lower in PD patients compared to controls (p < 0.001). The patients with EDS had higher levels of MDA and lower levels of BDNF as compared to those without EDS (p < 0.005). In linear regression analysis, the BDNF levels were dependently associated with SOD levels in PD patients (B: 0.274, p: 0.043). In addition, while a negative correlation existed between BDI scores with BDNF levels (r = –0.312, p = 0.004), a positive correlation was present between BDI scores and MDA levels (r = 0.320, p = 0.005) in PD patients. Conclusion: Our results suggest the presence of high O&NS and low antioxidant capacity accompanied with decreased levels of BDNF in PD patients, especially those with EDS were deeper. These may represent the risk factors for cellular injury and might reveal part of the mechanism causing the depressive state in PD patients.