Ghrelin mediates exercise endurance and the feeding response post-exercise.

Area of Science:

• Endocrinology and Metabolism
• Exercise Physiology
• Molecular Biology

Background:

• Exercise offers significant health benefits, impacting body weight, appetite, and blood glucose.
• The precise molecular and hormonal pathways mediating these exercise effects remain largely unknown.
• Ghrelin, a key appetite-regulating hormone, and its receptor, GHSR, are potential mediators.

Purpose of the Study:

• To investigate the role of the ghrelin hormone and its receptor (GHSR) in exercise responses.
• To determine the impact of the ghrelin system on food intake, blood glucose, and exercise endurance.
• To elucidate the molecular mechanisms underlying exercise adaptation.

Main Methods:

• Utilized treadmill running in two mouse models: wild-type and growth hormone secretagogue receptor-null (GHSR-null) mice.
• Measured plasma acyl-ghrelin levels following acute exercise bouts.
• Assessed food intake, blood glucose, exercise endurance, sympathoadrenal response, IGF-1 levels, and glycogen utilization.

Main Results:

• Acute exercise transiently elevated plasma acyl-ghrelin levels.
• GHSR-null mice exhibited significantly reduced food intake after high-intensity interval exercise.
• Exercise-induced blood glucose elevation was unaffected in GHSR-null mice; however, endurance capacity was reduced, linked to impaired sympathoadrenal response, lower IGF-1, and altered glycogen metabolism.

Conclusions:

• Exercise transiently increases circulating ghrelin.
• An intact ghrelin system (GHSR) is crucial for modulating post-exercise food intake and enhancing exercise endurance.
• The ghrelin system plays a dual role: it limits exercise-induced appetite suppression while promoting endurance capacity.