AUTHOR=Nieman David C. , Zwetsloot Kevin A. , Meaney Mary Pat , Lomiwes Dominic D. , Hurst Suzanne M. , Hurst Roger D. 

TITLE=Post-Exercise Skeletal Muscle Glycogen Related to Plasma Cytokines and Muscle IL-6 Protein Content, but not Muscle Cytokine mRNA Expression

JOURNAL=Frontiers in Nutrition

VOLUME=2

YEAR=2015

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2015.00027

DOI=10.3389/fnut.2015.00027

ISSN=2296-861X

ABSTRACT=<sec id="ST1"><title>Objectives</title><p>The purpose of this study was to correlate post-exercise muscle glycogen levels with changes in plasma cytokine, and muscle mRNA cytokine expression and protein content.</p></sec><sec id="ST2"><title>Methods</title><p>Twenty-four male runners (age 36.5 ± 1.8 years, VO<sub>2max</sub> 60.0 ± 1.5 mL⋅kg<sup>−1</sup> ⋅ min<sup>−1</sup>) ran twice (separated by 4 weeks) on treadmills to exhaustion at 70% VO<sub>2max</sub> (average time and distance of 2.24 ± 0.09 h and 24.9 ± 1.1 km). Muscle biopsies from the vastus lateralis and blood samples were collected before and after each run, with IL-6, IL-8, and MCP-1 measured in muscle (mRNA and protein) and plasma. Data from the two runs were averaged.</p></sec><sec id="ST3"><title>Results</title><p>Participants experienced a 35.3 ± 4.2% decrease (<italic>P</italic> &lt; 0.001) in skeletal muscle glycogen content (67.5 ± 2.8 to 44.3 ± 3.7 mmol⋅kg<sup>−1</sup> wet weight). Muscle mRNA expression for IL-6, IL-8, and MCP-1 increased 7.34 ± 0.90-, 13.9 ± 2.3-, and 4.10 ± 0.60-fold, respectively (all, <italic>P</italic> &lt; 0.001). Skeletal muscle IL-6, IL-8, and MCP-1 protein content increased 35.8 ± 10.6, 80.6 ± 12.1, and 105 ± 17.9%, respectively (all, <italic>P</italic> ≤ 0.005). Plasma IL-6, IL-8, and MCP-1 increased 47.1 ± 10.0-, 2.6 ± 0.3-, and 1.6 ± 0.1-fold, respectively (all, <italic>P</italic> &lt; 0.001). Post-exercise muscle glycogen concentrations were negatively correlated with run time to exhaustion (<italic>r</italic> = −0.70, <italic>P</italic> &lt; 0.001), and changes in muscle IL-6 protein content (<italic>r</italic> = −0.44, <italic>P</italic> = 0.049), plasma IL-6 (<italic>r</italic> = −0.72, <italic>P</italic> &lt; 0.001), IL-8 (<italic>r</italic> = −0.60, <italic>P</italic> = 0.002), and MCP-1 (<italic>r</italic> = −0.589, <italic>P</italic> = 0.002), but not with changes in muscle IL-8 and MCP-1 protein content, or muscle mRNA expression for IL-6, IL-8, and MCP-1.</p></sec><sec id="ST4"><title>Conclusion</title><p>Prolonged and intensive running increased muscle mRNA expression, muscle protein content, and plasma levels for IL-6, IL-8, and MCP-1, and post-run muscle glycogen levels were most strongly related to plasma cytokine levels.</p></sec>