Effect of exercise on activation of the p38 mitogen-activated protein kinase pathway, c-Jun NH2 terminal kinase, and heat shock protein 27 in equine skeletal muscle.

The research study investigates how the proteins in the mitogen-activated protein kinase (MAPK) pathway in horses are affected by exercise. The study finds increases in the activation of specific proteins following exercise, indicating a role of these proteins in muscle response to physical activity.

Study Methods

• Six trained young Standardbred geldings comprised the research subjects.
• Each horse performed a 20-minute round of exercise on a treadmill, operating at 80% of their maximum heart rate.
• Biopsy samples were taken from two muscle groups, the vastus lateralis and pectoralis descendens, before and after the exercise session.
• The levels and intracellular locations of phosphorylation in the MAPK pathway intermediates were ascertained using western blotting and immunofluorescence staining techniques.

Findings

• The vastus lateralis muscle exhibited a significant upsurge in the phosphorylation levels of p38 pathway intermediates, c-Jun NH2 terminal kinase (JNK), and heat shock protein 27 (HSP27) post-exercise.
• No notable alterations were witnessed in the phosphorylation of extracellular regulated kinase in the same muscle group.
• In the pectoralis descendens muscle, the phosphorylation of p38 and HSP27 experienced a significant increase after exercise.
• Immunohistochemical analysis exposed specific locations of the phosphorylated JNK and p38 proteins in differing muscle fiber types, with an increase in the phosphorylated HSP27 in type 1 and 2a fibers after the exercise.

Conclusions

• Both the p38 pathway and JNK are activated within the vastus lateralis muscle post a single 20-minute session of submaximal exercise in the Standardbred geldings.
• The researchers believe the increased phosphorylation of HSP27 visualized in the study is likely an effect of the activation of the p38 signaling pathway.

Implications of study

• The research provides valuable insights into the ways exercise influences the protein pathways within horse muscle tissue. Such discoveries could be vital in understanding how to optimize performance and recovery in equine athletes.
• The findings also help enhance understanding of the cellular effects of exercise more generally, which may have implications for human muscle dynamics as well.