Stimulation of LH secretion by 0.5 µg/kg cKP10 in various stages of the estrous cycle and anestrus in the Beagle bitch.

Abstract

Background: Kisspeptins are recognized to be regulators within the hypothalamus-pituitary-gonadal axis and stimulators of GnRH and gonadotrophin secretion in mammals. In mice and sheep it is shown that mRNA expression of the Kiss1 gene and Kiss1R gene, as well as plasma LH concentrations varies between cycle phases. Little is known about sensitivity to kisspeptin between different cycle phases in the dog. Therefore the aim of the study is to find out whether there is a difference in sensitivity to kisspeptin throughout the different stages of the canine estrous cycle and anestrus. Methods: Beagle bitches were treated intravenously with cKP10 (0,5 µg/kg) during anestrus, follicular phase and luteal phase (PIP and PDP). Plasma LH concentrations are measured. Results: In each experimental phase, plasma LH concentrations increased significantly after cKP10 administration. LH response peaks were higher during anestrus and PDP compared to follicular phase and PIP. Conclusion: LH responses show that sensitivity to kisspeptin differs during the estrous cycle and anestrus of the Beagle bitch. LH response is high during anestrus and PDP compared to follicular phase and PIP. More research should be done to confirm our findings and the meaning of high plasma LH response during PDP should be further investigated.