Picton H M, Tsonis C G, McNeilly A S
MRC Reproductive Biology Unit, University of Edinburgh.
J Endocrinol. 1990 Nov;127(2):273-83. doi: 10.1677/joe.0.1270273.
The hypogonadotrophism model induced by the chronic administration of gonadotrophin-releasing hormone (GnRH) agonist was used to investigate the effects of different concentrations of FSH with or without LH pulses on the stimulation of follicular development in the ewe. Continuous administration of an agonist (buserelin) by osmotic minipump to thirty-six Welsh Mountain ewes from the early luteal phase for 5 weeks resulted in a sustained suppression of the plasma concentration of FSH and inhibited the pulsatile release of LH. The inhibition of gonadotrophin secretion was due to the desensitization and/or down-regulation of pituitary gonadotroph function, since the agonist-treated animals showed no response to a challenge of 1 microgram GnRH. During week 6 of agonist treatment, ewes were infused with either 4-hourly pulses of ovine LH (9 micrograms/pulse), low concentrations of ovine FSH (3 micrograms/h) or high concentrations of FSH (9 micrograms/h) alone or with 4-hourly pulses of LH. After 5 days of gonadotrophin infusion, there was no difference between the mean number of follicles per ewe from the animals treated with LH alone, low concentrations of FSH with or without LH pulses or the high concentration of FSH alone compared with the mean number of follicles from control ewes on day 8 of the luteal phase. Infusion of the high concentration of FSH alone stimulated the development of an increased number of large oestrogenic follicles (follicles greater than 2.5 mm in diameter and secreting greater than 3.7 nmol oestradiol/h in vitro) compared with control ewes. The addition of high-amplitude LH pulses to the infusion of the high concentration of FSH prevented follicles developing beyond 2.5 mm in diameter, but doubled the number of small follicles (less than or equal to 2.5 mm) present in the ovaries. These results show that normal follicular development can be induced by physiological concentrations of FSH alone in the absence of pulsatile LH release. The addition of high-amplitude LH pulses antagonized this stimulatory effect of FSH on follicle growth in the ewe.
采用长期注射促性腺激素释放激素（GnRH）激动剂诱导的性腺功能减退模型，研究不同浓度的促卵泡素（FSH）在有或无促黄体生成素（LH）脉冲情况下对母羊卵泡发育刺激作用的影响。从黄体期早期开始，用渗透微型泵向36只威尔士山地母羊连续注射激动剂（布舍瑞林）5周，导致血浆促卵泡素浓度持续受到抑制，并抑制了促黄体生成素的脉冲式释放。促性腺激素分泌的抑制是由于垂体促性腺激素功能的脱敏和/或下调，因为经激动剂处理的动物对1微克GnRH的刺激无反应。在激动剂治疗的第6周，给母羊分别输注每4小时一次的绵羊促黄体生成素脉冲（9微克/脉冲）、低浓度的绵羊促卵泡素（3微克/小时）或高浓度的促卵泡素（9微克/小时），单独使用或与每4小时一次的促黄体生成素脉冲联合使用。在输注促性腺激素5天后，单独用促黄体生成素处理的动物、低浓度促卵泡素（无论有无促黄体生成素脉冲）或单独高浓度促卵泡素处理的母羊，其每只母羊的卵泡平均数量与黄体期第8天的对照母羊卵泡平均数量之间没有差异。与对照母羊相比，单独输注高浓度促卵泡素刺激了更多大的雌激素生成卵泡（直径大于2.5毫米且体外分泌雌二醇大于3.7纳摩尔/小时的卵泡）的发育。在高浓度促卵泡素输注中加入高幅度促黄体生成素脉冲可防止卵泡直径超过2.5毫米，但使卵巢中存在的小卵泡（小于或等于2.5毫米）数量增加一倍。这些结果表明，在没有促黄体生成素脉冲式释放的情况下，生理浓度的促卵泡素 alone 可诱导正常卵泡发育。高幅度促黄体生成素脉冲的加入拮抗了促卵泡素对母羊卵泡生长的这种刺激作用。
