Brain-Derived Neurotrophic Factor and Ciliary Neurotrophic Factor in Patients with Depression

We studied the content of brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF) in serum and lacrimal fluid in 105 patients with depression (unipolar depression, 37 and bipolar depression, 68). The stimulated lacrimal fluid was taken from one randomly selected eye with a pipette dispenser. The concentrations of BDNF and CNTF were determined by enzyme-linked immunosorbent assay. We observed a decrease in the concentration of BDNF in the blood serum of patients (22 380 +/- 3600 pg/mL) compared to healthy controls (25 220 +/- 3550 pg/mL). The concentration of CNTF in patients was increased both in blood serum (6.7 +/- 2.8 compared with 4.4 +/- 2.3 pg/mL) and in lacrimal fluid (35.8 +/- 9.8 vs 31.0 +/- 5.3 pg/mL). CNTF values in blood serum and in the lacrimal fluid weakly correlated with each other. The increase in the level of CNTF in lacrimal fluid of patients with depression indirectly indicates an increase in CNTF in the aqueous humor of the anterior chamber of the eye, and possibly in the cerebrospinal fluid, which, requires further study.