Skeletal muscle alterations and exercise performance decrease in erythropoietin-deficient mice: a comparative study

Area of Science:

• Exercise Physiology
• Molecular Biology
• Genomics

Background:

• Erythropoietin (EPO) enhances oxygen transport and exercise performance (VO2max).
• EPO demonstrates protective effects in various tissues, including the myocardium.
• The direct impact of physiological EPO levels on skeletal muscle remains unclear, despite identified EPO receptors.

Purpose of the Study:

• To investigate the impact of functional EPO deficiency on exercise performance in mice.
• To analyze muscle transcriptome alterations in a murine EPO functional knock-out model.
• To explore potential direct protective effects of EPO on skeletal muscle.

Main Methods:

• Determined VO2max, peak velocity, and critical speed in EPO-deficient (EPO-d) and control mice via treadmill exercise.
• Collected tibialis anterior and soleus muscles 24 hours post-exercise for RNA extraction.
• Conducted microarray gene expression analysis to identify transcriptome changes.

Main Results:

• EPO-d mice exhibited ~50% lower hematocrit and ~25% reduced exercise performance.
• Significant changes in gene expression were observed, with 68 genes upregulated and 115 downregulated.
• Transcriptome analysis revealed exercise-induced muscle hypoxia, oxidative stress, and proteolysis in EPO-d mice, linked to energy pathway disruptions.

Conclusions:

• Lack of functional EPO impairs aerobic exercise capacity, correlating with reduced hematocrit and muscle oxygen supply.
• Altered muscle transcriptome suggests physiological EPO concentrations provide direct and indirect muscle-protective effects during exercise.
• Further research is needed to elucidate the specific signaling pathways involved in EPO's muscle-protective mechanisms.