Differential release of LH and FSH in cyclic mares in response to synthetic Gn-RH.

This study explores how synthetic Gonadotropin-releasing hormone (Gn-RH) affects the release of two hormones – Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH) – in mares during various stages of their oestrous cycle. The key finding is that the response, measured in terms of peak area and height, can significantly vary across different stages, indicating that a single releasing hormone can trigger the release of both FSH and LH.

Research Objective and Methodology

• The objective of this research was to understand how a synthetic version of Gn-RH affects the release of LH and FSH hormones in mares at different stages of their oestrous cycle.
• The methodology involved administering a single intravenous injection of synthetic Gn-RH (0.5 mg) to the mares and subsequently monitoring the reaction of LH and FSH hormones.

Key Findings

• There significant variability was observed in the induced LH peak area and peak height at different stages of the mare’s oestrous cycle. Specifically, the LH peak area was significantly smaller at mid-cycle (Day 10-11) than at any other stage. Similarly, the LH peak height above the preinjection level was greater at late oestrus and early cycle (Day 5-6) than at other stages.
• The research did not find any significant differences in the mean FSH response at varying stages of the mare’s cycle.
• The ratio of LH to FSH, calculated based on peak height and area, was significantly smaller at mid-cycle compared to other times of injection.

Implications

• These findings suggest that a single releasing hormone – Gn-RH – can trigger the release of both FSH and LH. As such, it could have implications for managing hormonal imbalances or disorders in animals.
• The specific reaction of the hormones to synthetic Gn-RH at different stages of the mare’s cycle could help in better understanding the hormonal dynamics and providing a more tailored treatment or care during specific stages of the oestrous cycle.