title: Interleukin-6 release from the human brain during prolonged exercise.
abstract: Interleukin (IL)-6 is a pleiotropic cytokine, which has a variety of physiological roles including functions within the central nervous system. Circulating IL-6 increases markedly during exercise, partly due to the release of IL-6 from the contracting skeletal muscles, and exercise-induced IL-6 may be linked with central fatigue, which is enhanced by hyperthermia. Exercise-induced IL-6 may also stimulate hepatic glycogenolysis, which is important during prolonged and repeated exercise. Thus, in a randomised order and separated by 60 min of rest, eight young male subjects completed two 60 min exercise bouts: one bout with a normal (38 degrees C) and the other with an elevated (39.5 degrees C) core temperature. The cerebral IL-6 response was determined on the basis of internal jugular venous to arterial IL-6 differences and global cerebral blood flow. There was no net release or uptake of IL-6 in the brain at rest or after 15 min of exercise, but a small release of IL-6 was observed after 60 min of exercise in the first bout (0.06 +/- 0.03 ng min(-1)). This release of IL-6 from the brain was five-fold greater at the end of the second bout (0.30 +/- 0.08 ng min(-1); P < 0.05) with no separate influence of hyperthermia. In conclusion, IL-6 is released from the brain during prolonged exercise in humans and it appears that the duration of the exercise rather than the increase in body temperature dictates the cerebral IL-6 response.
authors.affiliation: Department of Human Physiology, Institute of Exercise and Sport Sciences, University of Copenhagen, Denmark. lnnielsen@aki.ku.dk
authors.forename: Lars
authors.initials: L
authors.lastname: Nybo
authors.forename: Bodil
authors.initials: B
authors.lastname: Nielsen
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
authors.forename: Kirsten
authors.initials: K
authors.lastname: Møller
authors.forename: Niels H
authors.initials: NH
authors.lastname: Secher
mesh_terms: D000328:Adult; D001158:Arteries; D001831:Body Temperature; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006801:Humans; D015850:Interleukin-6 / Q000097:blood / Q000378:metabolism*; D007601:Jugular Veins; D008297:Male; D011897:Random Allocation; D013997:Time Factors
chemical_list: D015850:Interleukin-6