Induction of cyclic ovarian activity in seasonally anoestrous ewes with exogenous GnRH.
Anoestrous ewes (N = 3) were treated with a 500 ng GnRH pulse administered via a jugular cannula every 2 h for 40 to 80 days. Plasma concentrations and therefore presumed ovarian activity changed cyclically with each progestational cycle (n = 10) lasting 14.0--18.5 days. It is concluded that, by increasing the frequency of GnRH secretory episodes from an apparent endogenous level of one episode per 3.6 h to at least one every 2.0 h, cyclic ovarian activity can be restored to seasonally anoestrous sheep.
D000780:Anestrus / Q000187:drug effects*; D000818:Animals; D004971:Estrus / Q000187:drug effects*; D005260:Female; D010053:Ovary / Q000187:drug effects*; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood / Q000378:metabolism; D011863:Radioimmunoassay; D012621:Seasons; D012756:Sheep / Q000502:physiology*
D010906:Pituitary Hormone-Releasing Hormones; D011374:Progesterone