Diurnal variation of ghrelin, leptin, and adiponectin in Standardbred mares.

The research article presents a study that investigated if there are daily fluctuations in the hormones that regulate energy balance in Standardbred mares. It was found that the levels of ghrelin and leptin in the blood peaked after the afternoon meal and declined overnight, while the concentrations of glucose, insulin, and cortisol showed different patterns.

Study Overview

• Twelve Standardbred mares were included in this experiment.
• Blood samples were collected over a 24-hour period to measure the levels of several hormones involved in energy regulation, including active ghrelin, adiponectin, leptin, glucose, insulin, and cortisol.
• The experiment was carried out under stable conditions, with the horses receiving hay and pelleted grain at specific times: in the morning (0730) and in the afternoon (1530)

Key Findings

• The study found that blood concentrations of active ghrelin and leptin both peaked 20 minutes after the afternoon feeding (at 1550), and then dropped overnight.
• This variation, or fluctuation, was not observed following the morning meal.
• Concentrations of glucose and insulin in the plasma increased after feeding, with the morning responses being greater than the afternoon responses.
• Cortisol levels increased during morning hours, but did not respond to feeding. In contrast, adiponectin levels remained stable throughout the study.

Implications and Conclusions

• The observations suggest that in horses, the concentrations of active ghrelin and leptin may be regulated by meal feeding. This differs from adiponectin, which seems to be unaffected by feeding times.
• The study concluded that there is a daily fluctuation in glucose and insulin response to meals in horses, with higher concentrations observed following the morning feeding.
• This increase in glucose and insulin levels in the morning could potentially be responsible for the increased concentration of leptin observed in the afternoon.