Stewart F, Allen W R
J Reprod Fertil. 1981 Jul;62(2):527-36. doi: 10.1530/jrf.0.0620527.
The role of equine chorionic gonadotrophin (CG, formerly termed Pregnant Mare serum Gonadotrophin, PMSG) in maintaining equine pregnancy was investigated by examining the effects of this hormone on the maternal ovaries during early gestation and relating these findings to the receptor binding activities of CG in vitro. Measurement of plasma progestagen profiles in mares and donkeys carrying horse, donkey, mule ( female horse X male donkey) and hinny (female donkey X male horse) conceptuses confirmed that CG induced several secondary ovulations and thus maintained maternal progestagen concentrations. However, in mares carrying horse and mule conceptuses and in donkeys carrying donkey conceptuses the growth of the follicles that gave rise to the secondary corpora lutea occurred before CG was secreted and the CG did not express any FSH-like activity. Nevertheless, in donkeys carrying hinny pregnancies the CG secreted by the hinny conceptus stimulated massive follicular growth in addition to luteinization, presumably because of an enhanced sensitivity of donkey ovaries to hinny CG which, as demonstrated in previous studies, is a mixture of horse and donkey CG and hence has considerably more FSH-like activity than normal donkey CG. In-vitro receptor binding experiments showed that both horse and donkey gonadal tissues possessed a low binding affinity for horse CG compared to that exhibited by equivalent gonadal tissues of other species. Furthermore, horse CG bound with low, but significant, affinity to horse and donkey LH receptors and donkey FSH receptors, but exhibited negligible binding to horse FSH receptors. We suggest that in equids the receptor-mediated refractoriness to the gonadotrophic activities of the intraspecific chorionic gonadotrophin protects the ovaries during pregnancy.
通过研究马绒毛膜促性腺激素（CG，以前称为孕马血清促性腺激素，PMSG）在妊娠早期对母马卵巢的影响，并将这些发现与CG在体外的受体结合活性相关联，来探讨其在维持马妊娠中的作用。对怀有马、驴、骡（母马×公驴）和驴骡（母驴×公马）胚胎的母马和母驴的血浆孕酮水平进行测量，证实CG诱导了几次继发性排卵，从而维持了母体孕酮浓度。然而，在怀有马和骡胚胎的母马以及怀有驴胚胎的母驴中，产生继发性黄体的卵泡生长发生在CG分泌之前，且CG不表现出任何促卵泡素（FSH）样活性。尽管如此，在怀有驴骡妊娠的母驴中，驴骡胚胎分泌的CG除了使卵泡黄素化外，还刺激了大量卵泡生长，这可能是因为驴卵巢对驴骡CG的敏感性增强，如先前研究所示，驴骡CG是马和驴CG的混合物，因此比正常驴CG具有更多的FSH样活性。体外受体结合实验表明，与其他物种的等效性腺组织相比，马和驴的性腺组织对马CG的结合亲和力较低。此外，马CG与马和驴的促黄体生成素（LH）受体以及驴的FSH受体以低但显著的亲和力结合，但与马的FSH受体结合可忽略不计。我们认为，在马科动物中，受体介导的对种内绒毛膜促性腺激素促性腺活性的不应性在妊娠期间保护了卵巢。
