Interplay Among the Daily Rhythm of the Thyroid Hormones, Uncoupling Protein 1 and the Clock Gene Per2 in Horses.

The research article discusses a study that investigates the daily changes in certain hormones and proteins in horses. The aim was to understand how these changes interact and what effect they have on the animals’ well-being.

Objective of the Study

• The primary goal of this investigation is to evaluate the daily fluctuations of serum concentrations of 3,5,3′-triiodothyronine (T3) and thyroxine (T4) in conjunction with the daily fluctuation of uncoupling protein 1 (UCP1) and a clock gene named Per2 in healthy, domestic horses.
• The ultimate intent is to increase our understanding of these processes, which could lead to the enhancement of animal welfare, particularly regarding their thermal homeostasis.

Methodology

• Seven healthy female Italian Saddle horses, each 8-10 years old and weighing approximately 510 ± 32 kg, were selected for the study. They were housed individually under natural photoperiod and environmental conditions, including temperature and humidity.
• Blood samples were collected from these horses at four-hourly intervals over the course of two days. These samples were used to measure levels of T3, T4, UCP1, and the clock gene Per2.
• The researchers then carried out a two-way analysis of variance (ANOVA) on the collected raw data.

Findings

• The ANOVA analysis revealed a significant effect of time of day on all the studied parameters.
• A robust daily rhythm of T3, T4, and Per2 hormones was observed. Notably, T3 showed a diurnal rhythm, peaking at about 5 hours after sunrise. T4 peaked in the middle of the scotophase (period of darkness), and Per2 peaked close to sunrise.
• Contrarily, UCP1 levels remained constant over the two days.

Conclusion

• The findings of the study indicate that, in horses under natural environmental conditions not subjected to thermal stress, there is a daily rhythm of thyroid hormones (T3 and T4) associated with a daily rhythm of Per2 expression in peripheral blood.
• The investigation provides valuable insight into the circadian rhythm of horses, potentially paving the way for improved husbandry practices that can lead to increased animal comfort and welfare.