Differential Myokine Responses To Swimming: Highlighting Meteorin-Like (Metrnl) as a Unique Marker of Adaptation

Abstract

Objective: We examined time-dependent changes in the levels of meteorin-like protein (Metrnl), interleukin (IL)-7, IL-8, and follistatin-like 1 (FSTL1) myokines in mouse gastrocnemius-soleus tissue and plasma samples following acute and long-term swimming exercises. Materials and Methods: Seventy 8-12 weeks-old adult male BALB/c mice were classified as control (sedentary) and exercise groups. Either an acute or chronic exercise regime was applied to the exercise group. Samples were collected at 0 h, 3 h, and 48 h. The acute exercise group completed a 30-min single swimming session. The chronic exercise group completed the 30-min swimming exercise every day, 5 days a week, for 6 weeks. Metrnl, IL-7, IL-8, and FSTL1 levels in the m. gastrocnemius-soleus muscle and plasma samples were determined by enzyme-linked immunosorbent method (ELISA) kits. Results: No changes were observed in the Metrnl, IL-7, IL-8, and FSTL1 levels in the gastrocnemius-soleus muscle complex following acute or 6 weeks of swimming exercise (p>0.05). IL-7, IL-8, and FSTL1 levels did not change in the plasma in response to the exercises (p>0.05). Plasma Metrnl levels were higher at 3 h after 6 weeks of chronic exercise compared with the control (sedentary) and the 3 h samples of the acute swimming (3.49 +/- 1.75 ng/mL, 1.75 +/- 0.48 ng/mL, and 1.66 +/- 0.33 ng/mL; p<0.001, respectively) groups. Conclusion: These findings suggest that unlike IL-7, FSTL1, and IL-8, only Metrnl may playa role in mediating adaptation to long-term exercise in mice.