Induction of pulsatile secretion of leptin in horses following thyroidectomy.

The given research article presents an in-depth look into the endocrine characteristics of Quarter Horse-type mares in a state of 68 hours of food deprivation, and what changes were observed after undergoing surgical thyroidectomy.

Objective of the Research

The core aim of this research was to examine the reaction of the endocrine system in horses, specifically Quarter horse-type mares, due to a prolonged period of food deprivation, and the subsequent effect brought about by thyroidectomy on said horses.

Research Method Used

• A crossover experimental design was devised in which the mares were made to follow two dietary regimes. On the one hand, some mares were given brome hay at their disposal (FED). On the other hand, some mares were left with no food (RES) for 68 hours.
• Throughout the experiment, blood samples were taken every 20 minutes starting 20 hours after the beginning of the food deprivation stage.

Results and Observations

• Post thyroidectomy (THX), triiodothyronine and thyroxine concentrations were found to be undetectable.
• Higher plasma concentrations of thyrotropin were observed after THX as compared to before it.
• Leptin plasma concentrations were also found to be greater in the FED group post THX, compared to the RES group.
• A significant discovery was the presence of leptin pulse secretion exclusively post-THX. Before the surgical operation, these pulses were not seen.

Theoretical Explanation and Conclusions

• The researchers put forth a theory that the non-pulsatile secretion of leptin could have been a factor aiding the survival of horses as a species, considering they evolved in regions where there was seasonal food availability.
• The lack of pulsatile secretion of leptin might also promote the accumulation of energy stores by modulating leptin sensitivity.