Brain-derived neurotrophic factor in peripheral blood mononuclear cells from healthy adults following acute aerobic exercise and a 6-hour recovery in temperate and hot environments

Abstract

Brain-derived neurotrophic factor (BDNF) supports cognitive function and is released into systemic circulation in response to exercise or heat exposure. However, the relationship between exercise- and heat-induced BDNF responses in peripheral blood mononuclear cells (PBMCs) is poorly understood, especially across age groups. Therefore, we conducted a retrospective analysis of two studies. Study 1 assessed exercise-intensity dependent BDNF responses in PBMCs from 10 young (22 ± 2.2 years) and 10 older (70 ± 4.6 years) males following 30 min of cycling at 40 %, 55 %, and 70 % of peak oxygen consumption (VO_2peak) in a temperate environment (∼25 °C, 15 % relative humidity). Study 2 assessed the effect of ambient temperature on age- and sex-dependent BDNF responses in PBMCs from 20 young (23 ± 2.8 years) and 20 older (69 ± 3.8 years) adults (equal females) following 30 min of cycling at 70 % of VO_2peak in temperate and hot (40 °C, 15 % relative humidity) environments. PBMCs were assessed before, immediately after, and following 3 and 6 h of recovery via Western blot. In Study 1, BDNF content in PBMCs increased by ∼35 % following exercise in the temperate environment and remained elevated for 6 h, regardless of exercise intensity, with older males exhibiting greater increases than young males at 40 % of VO_2peak. In Study 2, heat exposure attenuated BDNF elevations by ∼15 % across groups. Altogether, we showed that exercise increases BDNF content in PBMCs, independent of intensity, in males. When exercise at 70 % of VO_2peak was performed in the heat, BDNF responses were attenuated irrespective of group.