Changes in circulating gut hormones in the horse during long distance exercise.

This research study investigates the changes in gut hormones in horses that occur during long-distance exercise, using blood sample analysis from an 80 km ride and a 42 km race. The researchers are trying to understand if such changes are part of the endocrine response to exercise.

Research Methodology

• The experiment involved collecting venous blood samples from horses before and immediately after they had partaken in an 80 km ride and a 42 km race.
• The blood samples were then analysed for:
  • Blood glucose and lactate, which are markers of metabolism and fatigue.
  • Plasma non-esterified fatty acids, which can indicate energy use and metabolic stress.
  • Various hormones, including insulin (which regulates blood sugar), pancreatic glucagon (which raises blood sugar), pancreatic polypeptide (related to pancreatic function), gastrin (which stimulates the stomach to secrete acid), gastric inhibitory peptide (which reduces stomach acid production), somatostatin (which inhibits the release of several other hormones), and vasoactive intestinal polypeptide (which has multiple effects including relaxing smooth muscle and stimulating water and electrolyte secretion).

Key Findings

• Following the 80 km ride, the horses showed marked hypoglycaemia (low blood sugar) and a slight increase in lactate levels (lactic acidaemia), indicating a shift in metabolism from aerobic to anaerobic.
• At the same time, there were increases in the levels of plasma glucagon, somatostatin, pancreatic polypeptide, and vasoactive intestinal polypeptide.
• The 42 km race resulted in hyperglycaemia (high blood sugar) and marked lactic acidaemia, along with an increase in plasma glucagon, somatostatin, and vasoactive intestinal polypeptide levels.
• The researchers found that these increased peptide levels were not related to alterations in blood glucose levels or changes in the relative contributions of aerobic and anaerobic muscle metabolism.

Conclusions

• The researchers suggest that the changes observed in the circulating gut hormones of the horses could be a part of the endocrine response to physical exercise.
• The exact physiological role of these hormonal changes in response to exercise is not clear yet and requires further investigation.