Triglyceride, insulin, and cortisol responses of ponies to fasting and dexamethasone administration.

The research investigates how ponies respond to fasting and exposure to a corticosteroid called dexamethasone, with a goal to reproduce and understand the hyperlipemia syndrome, a condition characterized by excess fat in the bloodstream.

Research Methodology

• The ponies’ responses to withholding of feed were studied and they were also exposed to dexamethasone treatment.
• Insulin resistance, which has been seen to be associated with hyperlipemia, was examined. Ponies were given an oral glucose load and normal dexamethasone administration, and the insulin response was monitored.
• Four ponies showed hyperinsulinemia which is indicative of insulin resistance.
• All of the ponies underwent a suppression of cortisol concentrations after being given dexamethasone.

Research Findings

• Withholding feed led to hypertriglyceridemia, a condition of elevated triglycerides in the bloodstream, within 48 hours in all ponies.
• The elevation was primarily seen in the very low-density lipoprotein-triglyceride (VLDL) fraction, a type of triglyceride.
• Contrary to expectation, administration of dexamethasone did not increase the level of triglycerides in the bloodstream (triglyceridemia).
• Despite insulin resistance being seen as a likely cause of hypertriglyceridemia, four out of the eight ponies in the study had normal insulin responses but still developed hypertriglyceridemia.

This study demonstrates that feed withholding leads to increased triglycerides in the bloodstream in ponies, and that certain metabolic characteristics, such as insulin resistance, may not necessarily predict this outcome. This suggests a more complex relationship between the animal’s metabolic state and hyperlipemia, indicating the need for further research to better understand the syndrome.