Muscular microRNA expressions in healthy and myopathic horses suffering from polysaccharide storage myopathy or recurrent exertional rhabdomyolysis.

This research explores the role of microRNAs (miRNA) in the muscles of healthy and myopathic horses. It investigates the relationship between miRNA expressions and two specific types of horsey muscle diseases, polysaccharide storage myopathy (PSSM) and recurrent exertional rhabdomyolysis (RER). The study found that different muscle diseases exhibit different miRNA expressions and these varied expressions are possibly significant enough to distinguish between healthy and diseased horses.

Objective and Methodology

The study aimed to identify potential miRNAs in the muscles of both healthy horses and those affected with PSSM or RER. To accomplish this objective, muscle samples were gathered from the gluteus medius of horses sorted into four groups, comprising of French Trotters and Norman Cob, both healthy and affected by either of the two diseases. Five types of miRNA assays were used to conduct a quantitative real-time PCR analysis on the extracted total RNA from these samples.

Key Findings

• All the miRNA candidates were detected significantly within the muscle samples, and occasionally in blood samples.
• It was found that the type of miRNA, the breed of the horse, and the pathology significantly influenced the miRNA expression. In other words, specific miRNA expressions were associated with specific forms of myopathy.
• For example, higher levels of mir-1, 133, 23a, 30b, 195, and 339 were detected in RER-affected French Trotters compared to control groups. Similarly, higher levels of mir-195 were found in PSSM-affected Norman Cob horses compared to the control group.
• Moreover, miRNA expressions also varied depending on the breed of the horse, which was evident from the different expressions of mir-181, 188, and 206.

Conclusions and Implications

This study is among the first to explore the muscular miRNA profile in equine myopathies. The results suggest a possible correlation between muscular miRNAs and particular muscle pathologies. These findings propose that these miRNAs could potentially serve as markers to differentiate between healthy and disease-affected horses, thus offering valuable diagnostic insights. The more unique and contrasting miRNA profile of RER compared to PSSM further strengthens this observation. However, further exploration and validation of these findings would be necessary for diagnostic application.