Plasma concentrations but not serum concentrations of brain-derived neurotrophic factor are related to pro-inflammatory cytokines in patients undergoing major abdominal surgery

ObjectivesTo investigate peripheral brain-derived neurotrophic factor (BDNF) concentrations in the perioperative period, their relationship with transforming growth factor-β1 (TGF-β1 tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-6 genetics.Design and methodsProspective, observational study. BDNF, TGF-β1, IL-6 and TNF-α were analysed at baseline (T0), 5 h (T1), 24 h (T2) and 5 days (T3) after surgery, in 21 patients. The IL-6 ? 174 G/C polymorphism was genotyped.ResultsSerum BDNF concentrations decreased (P = 0.048), correlated with TGF-β1 (r = 0.610 at T1, r = 0.493 at T2, r = 0.554 at T3). Plasma BDNF concentrations raised (P = 0.049), correlated with IL-6 and TNF-α at T1 (r = 0.495 and r = 0.441, respectively). BDNF response was predictable from TNF-α and IL-6 concentrations and the IL-6 ? 174 G/C genotype.ConclusionSerum and plasma BDNF concentrations could relate to platelet activation and inflammatory response, respectively. IL-6 genetics played a role in the BDNF acute response.