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In humans IL‐6 is released from the brain during and after exercise and paralleled by enhanced IL‐6 mRNA expression in the hippocampus of mice
Author(s) -
Rasmussen P.,
Vedel J.C.,
Olesen J.,
Adser H.,
Pedersen M. V.,
Hart E.,
Secher N. H.,
Pilegaard H.
Publication year - 2011
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/j.1748-1716.2010.02223.x
Subject(s) - endocrinology , medicine , hippocampus , hippocampal formation , rowing , glycogen , treadmill , chemistry , archaeology , history
Aim: Plasma interleukin‐6 (IL‐6) increases during exercise by release from active muscles and during prolonged exercise also from the brain. The IL‐6 release from muscles continues into recovery and we tested whether the brain also releases IL‐6 in recovery from prolonged exercise in humans. Additionally, it was evaluated in mice whether brain release of IL‐6 reflected enhanced IL‐6 mRNA expression in the brain as modulated by brain glycogen levels. Methods: Nine healthy male subjects completed 4 h of ergometer rowing while the arterio‐jugular venous difference (a‐v diff) for IL‐6 was determined. The IL‐6 mRNA and the glycogen content were determined in mouse hippocampus, cerebellum and cortex before and after 2 h treadmill running ( N = 8). Results: At rest, the IL‐6 a‐v diff was negligible but decreased to −2.2 ± 1.9 pg ml −1 at the end of exercise and remained low (−2.1 ± 2.1 pg ml −1 ) 1 h into the recovery ( P < 0.05 vs. rest). IL‐6 mRNA was expressed in the three parts of the brain with the lowest content in the hippocampus ( P < 0.05) coupled to the highest glycogen content (3.2 ± 0.8 mmol kg −1 ). Treadmill running increased the hippocampal IL‐6 mRNA content 2–3‐fold ( P < 0.05), while the hippocampal glycogen content decreased to 2.6 ± 0.6 mmol kg −1 ( P < 0.05) with no significant changes in the two other parts of the brain. Conclusion: Human brain releases IL‐6 both during and in recovery from prolonged exercise and mouse data suggest that concurrent changes in IL‐6 mRNA and glycogen levels make the hippocampus a likely source of the IL‐6 release from the brain.