Assessment of serum myokines and markers of inflammation associated with exercise in sled dogs

Abstract

Skeletal muscle inflammation and release of local myokines alter metabolism as well as local inflammation. Alterations in lipid and glycogen metabolism have been associated with local muscle synthesis of cytokines (IL-15, IL-8 and IL-6) which act locally in an autocrine fashion. Previous work suggests that the acute phase response (C-reactive protein) is heightened in endurance racing sled dogs, yet an inciting cause has yet to be elucidated and may involve these myokines. The endurance sled dog represents the ultimate endurance athlete to examine the acute phase (CRP), inflammatory (MCP-1, TNF-a) and myokine response (IL-6, IL-15, IL-8). Blood and body weights were taken from 28 sled dogs from three different teams before, in the middle, at the end of racing in the 2011 Yukon Quest endurance sled dog race. Results show that there were no significant increases or decreases in IL-6, IL-15, or IL-8 at the three different time points, while there were significant increases in MCP-1 (p < 0.01) and CRP (p<0.01) at the mid-point and end of the race. Further regression analysis examining relationships between myokines, MCP-1 and CRP show that there was a significant relationship between MCP-1 and IL-6 suggesting that as MCP-1 rises, IL-6 is influenced as well ( R = 0.68; p<0.05). These findings link the inflammatory response of exercise with interleukin-6, however the reasons for increases in the acute phase response (C-reactive protein) remain unknown.