Greaves H E, Kalariotes V, Cleaver B D, Porter M B, Sharp D C
Department of Animal Science, University of Florida, Gainesville, USA.
Theriogenology. 2001 Mar 15;55(5):1095-106. doi: 10.1016/s0093-691x(01)00469-1.
The potential involvement of ovarian factors in regulating GnRH and LH postovulation was studied in ovarian intact (Group 1; n=3) and ovariectomized (OVX; Group 2; n=3) mares (OVX within 12 hr of ovulation). Blood samples were collected every 10 min for 6 hr from jugular vein (JV) and intercavernous sinus (ICS) during estrus and on Day 8 postovulation for LH and GnRH analysis. Additionally, JV samples were collected twice daily (12-hr intervals) for 30 days for LH and progesterone (P4) analysis. A significant treatment x day effect (P<0.0001) describes declining plasma LH concentrations in intact mares, and regression analysis indicated that response curves were not parallel (P<0.001). Plasma LH concentrations remained elevated in OVX mares. LH increased further in OVX mares by Day 8 post-OVX (P<0.06), reflecting the increased (P<0.07) LH episode amplitude. GnRH decreased from estrus to Day 8 in both groups reflecting an effect of sampling period (P<0.03). GnRH episode amplitude declined (P<0.08) from estrus (62.8+/-3.1 pg/mL) to Day 8 (46.3+/-3.1 pg/mL) in OVX mares, but not in control mares (intact estrus, 36.5+/-6.4; intact Day 8, 37.5+/-7.3; OVX estrus, 62.8+/-3.1; OVX Day 8, 46.3+/-3.1 pg/mL). In conclusion, we propose that postovulatory LH decline requires ovarian feedback in mares, and that OVX alters GnRH secretory dynamics such that LH concentrations does not decline postovulation and, in fact, is further elevated with time after OVX.
研究了卵巢因素在排卵后调节促性腺激素释放激素（GnRH）和促黄体生成素（LH）方面的潜在作用，实验对象为卵巢完整的母马（第1组；n = 3）和卵巢切除的母马（OVX；第2组；n = 3）（在排卵后12小时内进行卵巢切除）。在发情期以及排卵后第8天，从颈静脉（JV）和海绵体间窦（ICS）每隔10分钟采集一次血样，共采集6小时，用于分析LH和GnRH。此外，每天（间隔12小时）采集两次JV血样，持续30天，用于分析LH和孕酮（P4）。显著的处理×天数效应（P<0.0001）表明，完整母马的血浆LH浓度下降，回归分析表明反应曲线不平行（P<0.001）。OVX母马的血浆LH浓度保持升高。OVX母马在卵巢切除后第8天LH进一步升高（P<0.06），反映出LH脉冲幅度增加（P<0.07）。两组中GnRH从发情期到第8天均下降，反映出采样期的影响（P<0.03）。OVX母马的GnRH脉冲幅度从发情期（62.8±3.1 pg/mL）到第8天（46.3±3.1 pg/mL）下降（P<0.08），而对照母马（完整发情期，36.5±6.4；完整第8天，37.5±7.3；OVX发情期，62.8±3.1；OVX第8天，46.3±3.1 pg/mL）则未下降。总之，我们提出排卵后LH下降需要母马的卵巢反馈，并且卵巢切除改变了GnRH分泌动力学，使得LH浓度在排卵后不下降，事实上，在卵巢切除后随时间进一步升高。
