Abstract
Brain-derived neurotrophic factor (BDNF) plays a key role in neuronal adaptations. While previous studies suggest that whole-body heating can elevate circulating BDNF concentration, this is not known for local heating protocols. This study investigated the acute effects of whole-body versus local passive heating on serum and plasma BDNF concentration. Using a water-perfused suit, ten recreationally active males underwent three 90 min experimental protocols: heating of the legs with upper-body cooling (LBH), whole-body heating (WBH) and a control condition (CON). Blood samples were collected before, immediately after and 1 h post-heating for the determination of serum and plasma BDNF concentration, platelet count as well as the BDNF release per platelet. Rectal temperature, cardiac output and femoral artery shear rate were assessed at regular intervals. Serum and plasma BDNF concentration were elevated after WBH (serum: 19.1±5.0 to 25.9±11.3 ng/ml, plasma: 2.74±0.9 to 4.58±2.0; p<0.044), but not LBH (serum: 19.1±4.7 to 22.3±4.8 ng/ml, plasma: 3.25±1.13 to 3.39±0.90 ng/ml; p>0.126), when compared with CON (serum: 18.6±6.4 to 16.8±3.4 ng/ml, plasma: 2.49±0.69 to 2.82±0.89 ng/ml); accompanied by an increase in platelet count (p<0.001). However, there was no change in BDNF content per platelet after either condition (p = 0.392). All physiological measures were elevated to a larger extent after WBH compared with LBH (p<0.001), while shear rate and rectal temperature were higher during LBH than CON (p<0.038). In conclusion, WBH but not LBH acutely elevates circulating BDNF concentration. While these findings further support the use of passive heating to elevate BDNF concentration, a larger increase in shear rate, sympathetic activity and/or rectal temperature than found after LBH appears needed to induce an acute BDNF response by passive heating.
Highlights
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family that plays a key role in neuroplasticity, learning and memory as well as metabolic regulation [1]
There was an effect of time (p
Deep tissue temperature was elevated to a larger extent by WBH compared with the other conditions (WBH: from 35.4±0.68 to 38.7±0.48, lower-body heating with upper-body cooling (LBH): from 35.7±0.62 to 37.3±0.42, CON: from 35.3±0.36 to 36.1±0.24; time x condition p
Summary
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family that plays a key role in neuroplasticity, learning and memory as well as metabolic regulation [1]. Acute and chronic aerobic exercise can elevate circulating BDNF concentration in humans [7]. Physical exercise is not universally accessible to all members of society, due to for instance disability, chronic disease or cognitive impairments. People with chronic heart failure may be advised against engagement in whole-body heating due to the attendant cardiovascular strain [14], while the impaired thermoregulation in older adults and persons with type II diabetes mellitus may place them at an increased risk for heat-illness during intense heat stress [15, 16]. Prior to promoting passive heating as a strategy to stimulate BDNF-mediated improvements in cognitive function, more accessible and physiologically less strenuous protocols may provide an additional tool to promote health in persons for whom whole-body heating may be contraindicated
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