LH release and luteal function in post-partum acyclic ewes after the pulsatile administration of LH-RH.
The administration of LH-RH in a pulsatile regimen (100 ng i.v./h for 48 h) to acyclic ewes 26-30 days post partum increased plasma LH concentrations, and both the frequency and amplitude of plasma LH pulses. In 12/14 ewes these increases were followed by plasma LH surges similar to the preovulatory surges observed in 10 control cyclic ewes. Subsequent luteal function in the post-partum ewes was deficient. Plasma progesterone was detected in 7/12 post-partum ewes showing plasma LH surges. The concentrations were lower (1.3 +/- 0.2 ng/ml) and detected for shorter periods (3-10 days) than in cyclic ewes (2.4 +/- 0.2 ng/ml, 12/15 days). In the post-partum ewes the increases in plasma LH concentrations before the LH surge were higher but of shorter duration than in the cyclic ewes. The inadequate luteal function in the post-partum ewes could therefore have been due to inappropriate LH stimulation of the ovary before the LH surge.
D000818:Animals; D003008:Cloprostenol / Q000494:pharmacology; D003338:Corpus Luteum / Q000187:drug effects / Q000502:physiology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000097:blood*; D049590:Postpartum Period; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
D007987:Gonadotropin-Releasing Hormone; D003008:Cloprostenol; D011374:Progesterone; D007986:Luteinizing Hormone