Gosden R G, Everett J W, Tyrey L
Endocrinology. 1976 Oct;99(4):1046-53. doi: 10.1210/endo-99-4-1046.
The LH requirements for ovulation in the pentobarbital-blocked proestrous CD rat have been studied by increasing serum gonadotropin levels through electrical stimulation of the brain and subsequently comparing the effects of timed hypophysectomy on ovulation and serum LH concentrations. The arcuate nucleus (ARC) or the medial preoptic area (POA) was stimulated unilaterally for 45 min with matched pairs of biphasic rectangular pulses through a coaxial platinum electrode. Serum LH was significantly elevated above basal values at the end of stimulation, but not in sham-stimulated controls. The results of both hormone measurement and hypophysectomy showed that the pituitary continued to release LH after extrinsic stimulation of the hypothalamus had ceased. Animals did not ovulate if they had been hypophysectomized at the end of the 45 min stimulation whereas nearly all ovulated if hypophysectomy was delayed for an additional 20 min. Some evidence suggested that the pituitary could be removed earlier without affecting ovulation if the rate of LH release was increased. The minimum peak LH concentration measured in rats that subsequently ovulated fully was 187 ng/ml, substantially lower than concentrations ordinarily attained in the spontaneous proestrous surge. When serum LH was insufficiently high to cause follicle rupture, there was nevertheless the resumption of meiosis and luteinization of the large ovarian follicles. Attempts were made to restore ovulability in animals presumed to have released a subovulatory quota of gonadotropin. Ovulation was obtained when such animals, prepared by hypophysectomy after the 45 min stimulation, had been bilaterally nephrectomized prior to stimulation. However, multiple injections of progesterone after hypophysectomy were without effect. The results are discussed in relation to variables that affect minimum requirements of LH for ovulation.
通过电刺激大脑提高血清促性腺激素水平，随后比较定时垂体切除对排卵和血清促黄体生成素（LH）浓度的影响，研究了戊巴比妥阻断的动情前期CD大鼠排卵所需的LH。通过同轴铂电极，用匹配的双相矩形脉冲单侧刺激弓状核（ARC）或内侧视前区（POA）45分钟。刺激结束时，血清LH显著高于基础值，但假刺激对照组未出现这种情况。激素测量和垂体切除的结果均表明，在下丘脑的外部刺激停止后，垂体仍继续释放LH。如果在45分钟刺激结束时进行垂体切除，动物不会排卵；而如果垂体切除延迟20分钟，几乎所有动物都会排卵。一些证据表明，如果LH释放速率增加，可以更早地切除垂体而不影响排卵。随后完全排卵的大鼠中测得的最低LH峰值浓度为187 ng/ml，大大低于自发动情前期LH峰通常达到的浓度。当血清LH不足以高到引起卵泡破裂时，大的卵巢卵泡仍会恢复减数分裂和黄体化。尝试恢复推测已释放亚排卵剂量促性腺激素的动物的排卵能力。当这些在45分钟刺激后通过垂体切除制备的动物在刺激前进行双侧肾切除时，可获得排卵。然而，垂体切除后多次注射孕酮无效。结合影响排卵所需LH最低要求的变量对结果进行了讨论。
