title: Age-related loss of associations between acute exercise-induced IL-6 and oxidative stress.
abstract: IL-6 mediates many aspects of the exercise-induced acute-phase response, including upregulation of antioxidant defenses. Moreover, IL-6 synthesis is regulated in part by oxidative stress. This investigation tested the hypothesis that an IL-6-mediated acute-phase response after exercise provides negative-feedback protection against exercise-induced oxidative stress. Healthy young (n = 16, 26.4 +/- 1.8 yr) and older men (n = 16, 71.1 +/- 2.0 yr) ran downhill for 45 min at 75% maximal oxygen consumption before and after a 12-wk period of supplementation with vitamin E (1,000 IU/day) or placebo. Circulating IL-6 and soluble IL-6 receptors, peripheral mononuclear cell production of IL-6, and IL-6 transcripts in muscle were measured before and within a 72-h time window after each acute exercise bout. At all time points plasma IL-6, IL-6 bioavailability, and C-reactive protein were higher in the older men; yet in response to exercise, young and older subjects experienced similar increases in these factors. Although the magnitude of postexercise changes in acute-phase variables was independent of age, correlations among plasma, mononuclear cell, and muscle IL-6 and oxidative stress were evident only in young men (R2 = 0.64, 0.35, and 0.33, respectively). These changes in circulating IL-6 were closely associated with a prooxidant state (R2 = 0.47), whereas muscle IL-6 mRNA correlated with an antioxidant state (R2 = 0.65). Supplementation with vitamin E did not affect exercise-induced responses or differences between the young and old men in a consistent manner. Therefore, oxidative stress is linked to the acute-phase response after exercise in young men, but not in older men who had elevated acute-phase reactants, suggesting that further research is warranted to determine the basis for these differences.
authors.affiliation: Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA 02111, USA. jennifer.sacheck@tufts.edu
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Sacheck
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Cannon
authors.forename: Koichiro
authors.initials: K
authors.lastname: Hamada
authors.forename: Edouard
authors.initials: E
authors.lastname: Vannier
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Blumberg
authors.forename: Ronenn
authors.initials: R
authors.lastname: Roubenoff
mesh_terms: D000210:Acute-Phase Reaction / Q000276:immunology* / Q000517:prevention & control*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000187:drug effects / Q000276:immunology*; D002097:C-Reactive Protein / Q000276:immunology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D015850:Interleukin-6 / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects / Q000276:immunology; D010807:Physical Endurance / Q000187:drug effects / Q000276:immunology*; D005082:Physical Exertion / Q000187:drug effects; D013223:Statistics as Topic; D014810:Vitamin E / Q000008:administration & dosage*
chemical_list: D015850:Interleukin-6; D014810:Vitamin E; D002097:C-Reactive Protein