Measurement of inhibin-A (α βA dimer) during the oestrous cycle, after manipulation of ovarian activity and during pregnancy in ewes
Measurement of inhibin-A (α βA dimer) during the oestrous cycle, after manipulation of ovarian activity and during pregnancy in ewes
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DOI：
10.1530/jrf.0.1130159
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发表时间：
1998-05-01
期刊：
影响因子：
--
通讯作者：
Groome, NP
中科院分区：
文献类型：
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作者：
Knight, PG;Feist, SA;Groome, NP
一种新的双位点ELISA验证绵羊血浆和用于测量循环中的Escherobin-A浓度在一个同步的发情周期在4只母羊和整个怀孕期间在6只母羊。在用GnRH激动剂长期治疗期间以及随后暴露于妊娠期血清促性腺激素（PMSG）以刺激卵巢卵泡发育后，还测定了4只母羊的抑制素A浓度。用放射免疫法测定FSH、LH、雌二醇和孕酮的浓度。ELISA的检测限约为50 pg/ml，与一系列相关分子（包括激活素A、激活素B、卵泡抑素和α 2-巨球蛋白）没有观察到显著的交叉反应。抑制素-A的浓度低于检测限血浆垂体切除和卵巢切除母羊。在发情周期中，血浆中雌二醇浓度（约0.3-0.3 ng ml（-1））在卵泡期没有变化，而血浆雌二醇增加约10倍。在排卵前LH/FSH激增后，BABIN-A下降到最低点（约0.15 ng ml（-1）），与排卵后FSH升高的峰值一致。在接下来的2天里，FSH浓度下降到基础值，因为在排卵前LH/FSH激增后3天，BABIN-A浓度升高（P < 0.05）至峰值（约0.5 ng ml（-1））。在接下来的3天里，FSH值再次升高（P < 0.05），因为BABIN-A浓度下降到约0.25 ng ml（-1）（P < 0.05）。长期GnRH激动剂治疗抑制FSH浓度约50%，而Escherobin-A和雌二醇浓度低于检测限。在注射PMSG后2天内，阿糖胞苷-A（约4.5 ng ml（-1））和雌二醇（约20 pg ml（-1））的浓度增加到非常高的值，而FSH浓度进一步降低了50%。在妊娠的前60天内，血浆中的Escherabin-A和FSH浓度与未妊娠母羊相似，但Escherabin-A值在60 - 90天之间显著下降（7倍; P < 0.01），与FSH下降2倍（P < 0.05）一致。抑制素A和FSH浓度在妊娠的剩余时间内保持较低水平，并且在整个妊娠期间呈正相关（r = 0.48; P < 0.005）。这些观察结果支持卵巢抑制素A和雌二醇在控制母羊次级（排卵后）FSH激增方面的内分泌反馈作用，但表明雌二醇的增加是导致卵泡早期至中期FSH特征性减少的原因。从妊娠中期到晚期FSH分泌减少不能归因于胎儿-胎盘单位分泌增加的卵泡素-A，但很可能反映了该来源的类固醇分泌增加。
A new two-site ELISA was validated for ovine plasma and used to measure circulating inhibin-A concentrations during a synchronized oestrous cycle in four ewes and throughout pregnancy in six ewes. Inhibin A concentrations were also determined in four ewes during chronic treatment with a GnRH agonist and after subsequent exposure to pregnant mares' serum,gonadotrophin (PMSG) to stimulate ovarian follicular development. Concentrations of FSH, LH, oestradiol and progesterone were determined by radioimmunoassay. The detection limit of the inhibin-ii ELISA was approximately 50 pg ml(-1) and no significant crossreaction was observed with a range of related molecules including activin-A, inhibin-B, activin-B, follistatin and alpha(2)-macroglobulin. Inhibin-A concentrations were below the detection limit in plasma from hypophysectomized and ovariectomized ewes. During the oestrous cycle, plasma inhibin-A concentrations (approximately 0.3-0.3 ng ml(-1)) did not vary during the follicular phase whereas plasma oestradiol increased approximately tenfold. After the preovulatory LH/FSH surge, inhibin-A fell to a nadir (approximately 0.15 ng ml(-1)) coincident with the peak of the postovulatory FSH rise. During the next 2 days, FSH concentrations fell to basal values as inhibin-A concentrations increased (P < 0.05) to a peak (approximately 0.5 ng ml(-1)) 3 days after the preovulatory LH/FSH surge. Over the following 3 days, FSH values increased again (P < 0.05) as inhibin-A concentrations fell to approximately 0.25 ng ml(-1) (P < 0.05). Chronic GnRH agonist treatment suppressed FSH concentrations by about 50%, while inhibin-A and oestradiol concentrations fell below detection limits. Within 2 days after the PMSG injection, concentrations of inhibin-A (approximately 4.5 ng ml(-1)) and oestradiol (approximately 20 pg ml(-1)) had increased to very high values, while FSH concentrations had been reduced by a further 50%. Plasma concentrations of inhibin-A and FSH were similar to those in nonpregnant ewes during the first 60 days of gestation, but inhibin-A values fell markedly (sevenfold; P < 0.01) between days 60 and 90, coincident with a twofold decrease In FSH (P < 0.05). Inhibin A and FSH concentrations remained low for the remainder of gestation and were positively correlated throughout pregnancy (r = 0.48; P < 0.005). These observations support an endocrine feedback role for ovarian inhibin-A and oestradiol in controlling the secondary (postovulatory) FSH surge in ewes, but indicate that an increase in oestradiol is responsible for the characteristic reduction in FSH during the early to mid-follicular phase. The reduced secretion of FSH from mid- to late pregnancy cannot be attributed to increased inhibin-A secretion by the fete-placental unit, but most likely reflects increased steroid secretion from this source.