Campbell B K, Dobson H, Baird D T, Scaramuzzi R J
University of Edinburgh Department of Obstetrics and Gynaecology, Centre for Reproductive Biology, UK.
Anim Reprod Sci. 1997 Aug;48(2-4):219-34. doi: 10.1016/s0378-4320(97)00051-1.
A model designed to mimic the action of LH in preovulatory follicle development was evaluated. The model involved treatment of ewes with GnRHa (50 micrograms kg-1 24 h-1; GnRHa) at the time of luteal regression followed by exogenous LH administered as a series of bolus injections of varying frequency and amplitude. Ovarian responses to this regimen were compared to data derived from the same animals during a normal follicular phase. In experiment 1 four ewes with an autotransplanted ovary were treated with GnRHa followed by hourly LH (2.5 micrograms NIH-oLH-S25 i.v.) for 60 h at which time a further bolus of LH (25 micrograms i.v.) was given to mimic the LH surge. Plasma FSH profiles and the pattern and rate of secretion of oestradiol, inhibin, androstenedione and testosterone by the ovary in normal and GnRHa treated ewes were similar, but ovulation did not occur following the induced follicular phase. Experiment 2 examined the ability of a revised LH regimen to induce ovulation in normal intact ewes. Ewes (n = 11) were treated with GnRHa at the time of luteal regression followed by LH injections (1.25 micrograms i.v.) administered every 3 h for 12 h, every 2 h for the next 12 h and every hour for the following 36 h (3,2,1 regimen). After 60 h of LH injections the animals received an 8 h infusion of oLH (25 micrograms min-1) designed to mimic the pre-ovulatory LH surge. This treatment resulted in normal follicular phase patterns of LH and FSH and had no effect on the incidence (100%) or number (1.6 +/- 0.1) of ovulations when compared to a normal cycle (100% and 1.8 +/- 0.2). Experiment 3 examined the pattern of ovarian follicular development and hormone secretion stimulated by the 3,2,1 LH regimen in ewes with autotransplanted ovaries (n = 8). The LH regimen stimulated normal pre-ovulatory follicular development (normal 1.4 +/- 0.2; induced 1.6 +/- 0.2) and a normal pattern of ovarian oestradiol and androstenedione secretion. Pulse analysis showed, however, that baseline steroid secretion was lower in induced animals during the late follicular phase reflecting lower baseline LH at this stage. We conclude that administration of a GnRHa at the time of luteal regression in conjunction with frequent low amplitude pulses of exogenous LH induce follicular and hormonal patterns that closely mimic those observed following normal luteal regression and that this regimen represents a useful model to study the role of LH in the control of follicular selection.
对一个旨在模拟促黄体生成素（LH）在排卵前卵泡发育过程中作用的模型进行了评估。该模型包括在黄体退化时用促性腺激素释放激素类似物（GnRHa，50微克/千克，每24小时一次；GnRHa）处理母羊，随后以一系列不同频率和幅度的大剂量注射方式给予外源性LH。将该方案引起的卵巢反应与同一动物在正常卵泡期的数据进行比较。在实验1中，对4只自体移植卵巢的母羊先用GnRHa处理，然后每小时静脉注射LH（2.5微克美国国立卫生研究院促黄体生成素-S25），持续60小时，此时再静脉注射一次大剂量LH（25微克）以模拟LH峰。正常母羊和经GnRHa处理的母羊的血浆促卵泡素（FSH）曲线以及卵巢分泌雌二醇、抑制素、雄烯二酮和睾酮的模式及速率相似，但诱导卵泡期后未发生排卵。实验2研究了改良的LH方案诱导正常未阉割母羊排卵的能力。母羊（n = 11）在黄体退化时用GnRHa处理，随后每3小时静脉注射LH（1.25微克），持续12小时，接下来的12小时每2小时注射一次，随后的36小时每小时注射一次（3、2、1方案）。LH注射60小时后给动物输注8小时的促黄体生成素（25微克/分钟）以模拟排卵前LH峰。与正常周期（100%和1.8±0.2）相比，这种处理导致LH和FSH呈现正常卵泡期模式，且对排卵发生率（100%）或排卵数（1.6±0.1）没有影响。实验3研究了3、2、1 LH方案对自体移植卵巢母羊（n = 8）卵巢卵泡发育模式和激素分泌的影响。LH方案刺激了正常的排卵前卵泡发育（正常组1.4±0.2；诱导组1.6±0.2）以及卵巢雌二醇和雄烯二酮分泌的正常模式。然而，脉冲分析显示，诱导组动物在卵泡晚期的基线类固醇分泌较低，这反映了该阶段较低的基线LH水平。我们得出结论，在黄体退化时给予GnRHa并结合频繁的低幅度外源性LH脉冲，可诱导出与正常黄体退化后观察到的卵泡和激素模式非常相似的模式，并且该方案是研究LH在卵泡选择控制中作用的一个有用模型。
