Williams G L, Amstalden M, Blodgett G P, Ward J E, Unnerstall D A, Quirk K S
Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville, TX 78102, USA.
Theriogenology. 2007 Jul 1;68(1):67-75. doi: 10.1016/j.theriogenology.2007.03.024. Epub 2007 May 7.
Three experiments were conducted during the operational breeding season to confirm that continuous, subcutaneous infusion of low-dose GnRH would not disrupt established estrous cycles (Experiment 1), and test the hypotheses that a similar treatment would stimulate secretion of LH and induce development of ovulatory follicles in persistently anovulatory mares (Experiments 2 and 3). Treatment with GnRH (5 microg/h) increased (P<0.001) serum P4 during the luteal phase (7.7+/-0.5 versus 6.4+/-0.5 ng/mL), tended to increase serum LH (2.6+/-0.27 versus 1.9+/-0.25 ng/mL), and did not modify interovulatory intervals. In Experiment 2, GnRH treatment (2.5-5 microg/h) of persistently anovulatory mares increased (P<0.001) serum LH compared to controls (0.5+/-0.08 versus 0.1+/-0.03 ng/mL), with all GnRH-treated and no Control mares ovulating. Mares exhibiting Delayed Recrudescence (n=29) or Lactational Anovulation (n=18), were assigned randomly in Experiment 3 to receive either (1) GnRH/GnRH (n=23); 2.5 microg GnRH/h for 14 d (Period I) and 5 microg/h during the subsequent 28 d (Periods II and III); or (2) Control/GnRH (n=24); no treatment during Period I (control period) and GnRH treatments as in 1 during Periods II and III. Percentage of mares ovulating and pregnant during Period I was greater (P<0.05) for GnRH-treated than Control mares. Thereafter, cumulative ovulation frequency (85%), pregnancy (72%) and cycles/conception (1.3+/-0.2) were similar between groups; however, interval to conception was reduced (P<0.01) by 10.3 d in GnRH/GnRH compared to Control/GnRH.
在繁殖季节进行了三项实验，以确认持续皮下输注低剂量促性腺激素释放激素（GnRH）不会扰乱已建立的发情周期（实验1），并检验以下假设：类似的处理会刺激促黄体生成素（LH）的分泌，并诱导持续性无排卵母马的排卵卵泡发育（实验2和3）。GnRH（5微克/小时）处理使黄体期血清孕酮（P4）升高（P<0.001）（7.7±0.5对6.4±0.5纳克/毫升），血清LH有升高趋势（2.6±0.27对1.9±0.25纳克/毫升），且不改变排卵间期。在实验2中，持续性无排卵母马接受GnRH处理（2.5 - 5微克/小时），与对照组相比血清LH升高（P<0.001）（0.5±0.08对0.1±0.03纳克/毫升），所有接受GnRH处理的母马排卵，而对照组母马均未排卵。在实验3中，表现为发情延迟（n = 29）或泌乳期无排卵（n = 18）的母马被随机分配接受以下处理之一：（1）GnRH/GnRH（n = 23）；第1阶段（14天）2.5微克GnRH/小时，随后第2和第3阶段（28天）5微克/小时；或（2）对照/GnRH（n = 24）；第1阶段（对照期）不处理，第2和第3阶段与（1）组的GnRH处理相同。与对照母马相比，GnRH处理母马在第1阶段排卵和怀孕的百分比更高（P<0.05）。此后，两组之间的累积排卵频率（85%）、怀孕率（72%）和周期/受孕率（1.3±0.2）相似；然而，与对照/GnRH组相比，GnRH/GnRH组的受孕间隔缩短了10.3天（P<0.01）。
