IL-6 is not essential for exercise-induced increases in glucose uptake

Area of Science:

• Exercise Physiology
• Molecular Biology
• Metabolic Regulation

Background:

• Interleukin-6 (IL-6) is known to enhance glucose uptake in resting skeletal muscle.
• IL-6 is released by skeletal muscle during physical activity, but its specific role in exercise-induced glucose uptake remains unclear.

Purpose of the Study:

• To investigate the role of Interleukin-6 (IL-6) in regulating skeletal muscle glucose uptake and substrate utilization during endurance exercise.
• To determine if IL-6 knockout affects exercise capacity and metabolic responses in mice.

Main Methods:

• Utilized IL-6 knockout (KO) and wild-type (WT) mice models.
• Assessed resting metabolic parameters including body weight, oxygen consumption, food intake, substrate utilization, glucose tolerance, and insulin sensitivity.
• Measured in vivo substrate utilization and muscle glucose clearance during steady-state treadmill running at 70% of maximal capacity.
• Analyzed the phosphorylation of AMP-activated protein kinase (AMPK) T172.

Main Results:

• IL-6 KO mice exhibited similar body weight, resting metabolic profiles, and maximal exercise capacity compared to WT mice.
• During steady-state exercise, both WT and IL-6 KO mice demonstrated comparable rates of substrate utilization and muscle glucose clearance.
• Key metabolic signaling pathways, such as AMPK phosphorylation, were not significantly altered by the absence of IL-6 during exercise.

Conclusions:

• Interleukin-6 (IL-6) does not appear to play a critical role in the regulation of substrate utilization or skeletal muscle glucose uptake during endurance exercise.
• These findings suggest that other signaling pathways are primarily responsible for mediating the metabolic adaptations to exercise in skeletal muscle.