Kisspeptin stimulates LH secretion but not ovulation in mares during vernal transition.

This study investigates how the hormone kisspeptin impacts the secretion of Luteinizing hormone (LH) and the occurrence of ovulation in mares during the changeover from winter to spring. The research indicates that while kisspeptin does stimulate an increase in LH, it does not promote ovulation.

Objective and Background

The research aims to determine the efficacy of the hormone kisspeptin in managing the onset of regular cyclicity in mares after winter anestrus – a period of sexual dormancy. The equine breeding industry has long struggled with the task of either shortening or shifting the transition from winter anestrus to being reproductively active in mares. The researchers investigate the impact of kisspeptin, which is known to stimulate an LH response, on this transition.

Methodology

• The mares were administered an infusion of kisspeptin for 30 hours at varying rates or a saline solution.
• The levels of Luteinizing hormone (LH) and the follicular responses were observed and tracked over a series of time points.
• Initially, plasma samples were collected every 15 minutes for the first 6 hours to identify any immediate effects of the kisspeptin infusion on LH secretion.
• Next, plasma samples were collected every 3 hours for a total of 72 hours to assess whether the kisspeptin stimulated an LH surge.
• The researchers also monitored ovarian activity vis-à-vis follicular measurements collected using ultrasound until ovulation occurred or the follicles regressed.

Findings

• The kisspeptin infusion increased the secretion of LH in the mares.
• However, the kisspeptin was unable to stimulate an LH surge during the 72-hour observation period.
• The kisspeptin infusion at administered rates did not induce ovulation earlier than the control group of mares.

Implications

The research indicates the potential of using kisspeptin to manage the transition of mares from winter anestrus to reproductive activity by stimulating LH secretion. However, the kisspeptin infusion did not bring about an LH surge or promote earlier ovulation, pointing to the need for further research to refine these strategies before they can be applied for improved mare reproductive management.