Liu Xinyu, Dai Qiao, Hart Ezra J, Duggavathi Rajesha, Barrett David M W, Rawlings Norman C, Bartlewski Pawel M
Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ont. N1G 2W1, Canada.
Theriogenology. 2006 Sep 1;66(4):811-21. doi: 10.1016/j.theriogenology.2006.01.057. Epub 2006 Mar 10.
In the ewe, a rise in circulating concentrations of FSH preceding follicular wave emergence begins in the presence of growing follicles from a previous wave. We hypothesized that prostaglandin F(2alpha) (PGF(2alpha)) given at the time of an endogenous FSH peak in cyclic ewes would result in synchronous ovulation of follicles from two consecutive waves, increasing ovulation rate. Twelve Western White Face (WWF) ewes received a single i.m. injection of PGF(2alpha) (15 mg/ewe) at the expected time of a peak in FSH secretion, from Days 9 to 12 after ovulation. The mean ovulation rate after PGF(2alpha) treatment (2.3+/-0.3) did not differ (P>0.05) from the pre-treatment ovulation rate (1.7+/-0.1). Five ewes ovulated follicles from follicular waves emerging before and after PGF(2alpha) injection (3.0+/-0.6 ovulations/ewe) and seven ewes ovulated follicles only from a wave(s) emerging before PGF(2alpha) treatment (2.0+/-0.3 ovulations/ewe; P>0.05). The mean interval from PGF(2alpha) to emergence of the next follicular wave (1.0+/-0.4 and 4.0+/-0.0 d, respectively; P<0.001) and the interval from PGF(2alpha) treatment to the next FSH peak (0 and 3.5+/-0.4d, respectively; P<0.05) differed between the two groups. Six ewes ovulated after the onset of behavioral estrus, with a mean ovulation rate of 1.7+/-0.2, and six ewes ovulated both before and after the onset of estrus (3.0+/-0.5 ovulations/ewe; P<0.05). None of the ovulations that occurred before estrus resulted in corpora lutea (CL) with a full life span. At 24h before ovulation, follicles ovulating before or after the onset of estrus differed in size (4.1+/-0.3 or 5.5+/-0.4mm, respectively; P<0.05) and had distinctive echotextural characteristics. In conclusion, the administration of PGF(2alpha) at the expected time of an FSH peak at mid-cycle in ewes may alter the endogenous rhythm of FSH secretion and was not consistently followed by ovulation of follicles from two follicular waves. In non-prolific WWF ewes, PGF(2alpha)-induced luteolysis disrupted the normal distribution of the source of ovulatory follicles and may be associated with untimely follicular rupture and luteal inadequacy.
在母羊中，在卵泡波出现之前，循环中促卵泡素（FSH）浓度的升高始于前一波生长卵泡的存在。我们假设，在周期性母羊内源性FSH峰值出现时给予前列腺素F2α（PGF2α），将导致来自两个连续波的卵泡同步排卵，从而提高排卵率。12只西部白面（WWF）母羊在排卵后第9至12天，在预期的FSH分泌峰值时间接受单次肌肉注射PGF2α（15mg/只）。PGF2α处理后的平均排卵率（2.3±0.3）与处理前的排卵率（1.7±0.1）无差异（P>0.05）。5只母羊在PGF2α注射前后均有卵泡波出现时排卵（3.0±0.6次/只），7只母羊仅在PGF2α处理前有卵泡波出现时排卵（2.0±0.3次/只；P>0.05）。两组之间从PGF2α到下一个卵泡波出现的平均间隔（分别为1.0±0.4和4.0±0.0天；P<0.001）以及从PGF2α处理到下一个FSH峰值的间隔（分别为0和3.5±0.4天；P<0.05）不同。6只母羊在行为发情开始后排卵，平均排卵率为1.7±0.2，6只母羊在发情开始前后均排卵（3.0±0.5次/只；P<0.05）。发情前发生的排卵均未形成具有完整寿命的黄体（CL）。在排卵前24小时，发情开始前或后排卵的卵泡大小不同（分别为4.1±0.3或5.5±0.4mm；P<0.05），且具有独特的回声纹理特征。总之，在母羊周期中期预期的FSH峰值时间给予PGF2α可能会改变FSH分泌的内源性节律，且并非始终伴随着来自两个卵泡波的卵泡排卵。在非多产的WWF母羊中，PGF诱导的黄体溶解破坏了排卵卵泡来源的正常分布，可能与卵泡过早破裂和黄体功能不全有关。
