Differences In Plasma And Serum BDNF In Response To Acute HIIE

Abstract

PURPOSE: Circulating concentrations of brain-derived neurotrophic factor (BDNF) are reported to increase with acute exercise in a dose-dependent manner; however, the sources of elevated plasma and serum BDNF may differ as workload increases. Elevated plasma BDNF concentrations are believed to reflect release by the brain, which can indicate positive adaptations in brain health, whereas elevations in serum may reflect increased platelet release by the spleen. The popularity and documented benefits of high intensity interval exercise (HIIE), prompted the aim of this study to clarify the acute effects of low-volume, supramaximal HIIE on circulating BDNF. Furthermore, to examine a possible explanation for the changes in plasma BDNF, irisin, a protein involved in the mechanism linking muscle contraction and hippocampal BDNF release, was measured in plasma. METHODS: Healthy, sedentary males (N=11) participated in HIIE on a cycle ergometer (10 x 20 seconds of maximal pedaling against 5.5% of the subject’s body weight x 10 seconds of rest). Whole blood samples were collected from the antecubital vein prior to, immediately after (POST), and 15 minutes after (15POST) HIIE for BNDF and irisin analyses. RESULTS: At rest, serum BDNF concentrations were nearly 40-fold greater compared to plasma. Although no changes in plasma BDNF were observed after HIIE, serum BDNF increased at POST and 15POST (F (2,40) = 7.277, p = 0.002). Plasma irisin concentrations significantly decreased at POST (p = 0.029). In addition, a positive association between the total change in irisin and total change in plasma BDNF approached significance (r = 0.501, p = 0.097). CONCLUSIONS: These findings demonstrated that this low-volume, supramaximal HIIE protocol was sufficient for elevating serum BDNF, but not adequate for increasing circulating plasma BDNF in sedentary males. These results may suggest that the intensity of physical activity can differentially affect plasma and serum levels of BDNF. Additional research on HIIE volume and the mechanisms underlying BDNF responses (e.g. irisin) is warranted.