Kisspeptin Synchronizes Preovulatory Surges in Cyclical Ewes and Causes Ovulation in Seasonally Acyclic Ewes

We determined whether kisspeptin could be used to manipulate the gonadotropin axis and ovulation in sheep. First, a series of experiments was performed to determine the gonadotropic responses to different modes and doses of kisspeptin administration during the anestrous season using estradiol-treated ovariectomized ewes. We found that: 1) injections (iv) of doses as low as 6 nmol human C-terminal Kiss1 decapeptide elevate plasma LH and FSH levels, 2) murine C-terminal Kiss1 decapeptide was equipotent to human C-terminal Kiss1 decapeptide in terms of the release of LH or FSH, and 3) constant iv infusion of kisspeptin induced a sustained release of LH and FSH over a number of hours. During the breeding season and in progesterone-synchronized cyclical ewes, constant iv infusion of murine C-terminal Kiss1 decapeptide-10 (0.48 μmol/h over 8 h) was administered 30 h after withdrawal of a progesterone priming period, and surge responses in LH occurred within 2 h. Thus, the treatment synchronized preovulatory LH ...