Acute injection and chronic perfusion of kisspeptin elicit gonadotropins release but fail to trigger ovulation in the mare.

The research investigates the effect of a hormone called kisspeptin on inducing ovulation in mares after it showed promise in sheep. The study found that although kisspeptin increased levels of certain gonadotropins – hormones that stimulate the ovaries – it was not effective in triggering ovulation in mares.

Experiment and results

• Scientists carried out this research on Welsh pony mares to understand if kisspeptin – specifically its variant equine kisspeptin-10 (eKp10) – could be used to control ovulation similar to how it worked in sheep.
• eKp10 was administered to the ponies via direct injection or perfusion. This was done during the anestrus season (when females aren’t sexually receptive) and across different stages of the reproductive cycle during the breeding season.
• The treatment with eKp10 led to increased levels of luteinizing hormone and follicle-stimulating hormone – the two main gonadotropins – in all tested conditions and stages. These hormones are crucial for the development and release of eggs from the ovary.
• However, despite the increase in gonadotropin levels, eKp10 did not trigger ovulation in the mares.

Further Investigation

• To understand the mechanisms behind eKp10’s failure to stimulate ovulation, the researchers used acute injections or perfusions of gonadotropin-releasing hormone (GnRH).
• The researchers cloned the equine versions of the kisspeptin precursor and Kiss1r because the horse genome differs from other species regarding eKp10 and Kp10; also, the horse genome was missing an equine version of Kiss1r.

Implications

• The study’s findings showed that kisspeptin did not have a universal application as an ovulation-inducing agent as it failed to initiate ovulation in mares despite increasing gonadotropin levels.
• This suggests that the hormone’s effect differs between species, and the ability to control reproduction using kisspeptin would need specific research for each species.
• The lack of efficacy in triggering horse ovulation is also considered important for developing more understanding of kisspeptin’s role in animal reproduction.