Plasma Apelin Concentration in Exercised Horses: Preliminary Study.

Area of Science:

• Equine physiology and exercise science.
• Endocrinology and metabolic regulation in animals.

Background:

• Physical conditioning is vital for horse health, with blood parameters reflecting their overall condition.
• Apelin, a cytokine produced by adipocytes and myocytes, is crucial for energy metabolism but unstudied in horses.
• Understanding apelin's role can offer new insights into equine fitness and metabolic responses.

Purpose of the Study:

• To investigate the effect of varying physical exertion intensities on plasma apelin concentration in horses.
• To explore the relationship between apelin levels and other blood markers during and after exercise.
• To establish baseline apelin concentrations in trained versus untrained horses.

Main Methods:

• Involved 20 purebred Arabian horses, divided into racehorses (3 years) and endurance horses (6-12 years).
• Blood samples were collected from all horses at rest and post-exercise.
• Plasma concentrations of apelin, lactic acid, cortisol, uric acid (UA), triacylglycerols, total protein, and glucose were analyzed.

Main Results:

• Race training led to significant decreases in plasma apelin concentrations (P < .05).
• Endurance horses showed significant correlations between exercise-induced apelin changes and cortisol (r=0.55) and UA (r=0.67).
• Resting apelin levels were lower in regularly trained endurance horses compared to those starting training.

Conclusions:

• Equine plasma apelin concentration decreases after short-term, high-intensity exercise but not after endurance exercise.
• Apelin's response to exercise varies with intensity and duration in horses.
• Resting apelin levels may serve as an indicator of long-term training adaptation in equine athletes.