Reduced exercise endurance in interleukin-6-deficient mice.
IL-6 is produced and released in large amounts from skeletal muscle during prolonged exercise in both mice and humans, but there are few data indicating the biological significance of this. IL-6 exerts metabolic effects such as stimulating energy expenditure and reducing body fat mass. We have now investigated the effects of IL-6 deficiency on exercise endurance and energy expenditure in preobese and obese IL-6-deficient (IL-6(-/-)) mice. Four-month-old preobese and 7-month-old obese IL-6(-/-) male mice backcrossed to C57BL/6 and their littermate controls were exercised on a treadmill, and energy expenditure was measured as oxygen consumption with the use of indirect calorimetry. The preobese IL-6(-/-) mice were significantly leaner than the control mice, whereas the older IL-6(-/-) mice, as expected, had developed obesity. Resting young, but not older, IL-6(-/-) mice had an elevated respiratory exchange ratio (RER), indicating that they oxidize carbohydrates rather than fat for energy utilization. During exercise, the young and older IL-6(-/-) mice had a reduced endurance and a progressive decrease in oxygen consumption compared with control mice. There was no difference in RER in young IL-6(-/-) mice, whereas RER was enhanced in older IL-6(-/-), mice during exercise. In summary, IL-6(-/-) mice have reduced endurance and energy expenditure during exercise, suggesting that IL-6 is necessary for normal exercise capacity.
Fäldt
Jenny
J
Research Center for Endocrinology and Metabolism, Sahlgrenska University Hospital, Grona Straket 8, SE-413 45 Gothenburg, Sweden. jenny.faldt@medic.gu.se
Wernstedt
Ingrid
I
Fitzgerald
Sharyn M
SM
Wallenius
Kristina
K
Bergström
Göran
G
Jansson
John-Olov
JO
D000818:Animals; D001823:Body Composition; D004734:Energy Metabolism; D006003:Glycogen / Q000097:blood; D015850:Interleukin-6 / Q000172:deficiency / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity; D009765:Obesity / Q000097:blood / Q000378:metabolism / Q000503:physiopathology*; D010807:Physical Endurance / Q000502:physiology*; D011659:Pulmonary Gas Exchange
D015850:Interleukin-6; D006003:Glycogen