Whole-body repeated hyperthermia increases irisin and brain-derived neurotrophic factor: A randomized controlled trial

Abstract Context Hyperthermia is known to be beneficial to patients affected by various diseases. Irisin is a key regulators of fat metabolism known to be released as response to cold. Brain Derived Neurotrophic Factor (BDNF) is a marker of neuroplasticity usually increased as response to acute exposure to human body stressors. Objective Effect of a repeated hyperthermia exposure programme on changes in circulating irisin and serum BDNF in healthy humans. Design Setting, Participants: Randomized, single-blind, cross-over trial in healthy humans conducted at Sechenov University Physiology Laboratory from April 2019. The treatment period was 2 weeks (wash-out 3 weeks). Researchers analysing serum biomarkers and questionnaires data were blinded to participants allocation. Participants were 20 healthy male (age 21.5 ± 2.1 years). Intervention Hyperthermia exposure programme (WBPH) versus sham exposure (SHAM) to hyperthermia (10 sessions in two weeks). Main outcome measure Changes in irisin and BDNF before and after short hyperthermia exposure. Results Twenty participants were analysed. Irisin increased significantly in group WBPH only: 6.3 μg/ml (mean with SD = 1.6) compared to 5.4 μg/ml (SD = 1.7) in SHAM group; This value was also higher than baseline (5.0 mean with SD = 1.1) in WBPH. After 10 sessions mean change in BDNF was higher in WBPH group vs SHAM: BDNF was 28,263 (SD = 4213) pg/ml in WBPH group and 24,064 (SD = 5600) pg/ml in SHAM group. BDNF concentrations were significantly higher than baseline values in WBPH group only, 28,263 (SD 4213) vs 25,888 (SD 4316) pg/ml. Conclusion In healthy young humans a 2-week, ten sessions programme consisting of repeated exposure to hyperthermia resulted in a significantly higher increase of circulating Irisin and BDNF.