Thorson J A, Marshall J C, Bill C H, Keyes P L
Biol Reprod. 1985 Mar;32(2):226-31. doi: 10.1095/biolreprod32.2.226.
Rat ovarian tissue has been shown to contain high-affinity gonadotropin-releasing hormone (GnRH) receptors, and synthetic GnRH analogues have been shown to inhibit steroid production by rat corpora lutea in vivo and in vitro. These results raise the possibility that an ovarian GnRH-like peptide may be involved in normal luteal regression. We have examined binding of D-Ala6-des-Gly10-GnRH ethylamide (D-Ala) to rabbit corpora lutea, and have investigated the luteolytic activity of this analogue in hypophysectomized, pseudopregnant rabbits. Three hypophysectomized estrogen-treated rabbits were injected with 0.25 mg D-Ala s.c. every 6 h for 48 h during mid-pseudopregnancy, and three were injected with vehicle only. Treatment with D-Ala produced no acute changes in serum progesterone, nor was the time of luteal regression altered. Rabbit anterior pituitary tissue was found to contain high-affinity GnRH receptors (Ka = 7.0 X 10(9) M-1; 188.2 +/- 35.6 fmol/mg protein). However, no similar high-affinity GnRH receptors were detected in rabbit luteal tissue from any stage of pseudopregnancy. Some apparent low-affinity binding was observed, but this displaceable binding was subsequently observed in all control tissues tested. Thus, a potent GnRH analogue does not have any detectable direct effect on steroidogenesis in the rabbit corpus luteum, nor are high-affinity GnRH binding sites present in rabbit luteal tissue.
大鼠卵巢组织已被证明含有高亲和力的促性腺激素释放激素（GnRH）受体，并且合成的GnRH类似物已被证明在体内和体外均可抑制大鼠黄体的类固醇生成。这些结果提示，一种卵巢GnRH样肽可能参与正常的黄体退化过程。我们检测了D - Ala6 - des - Gly10 - GnRH乙酰胺（D - Ala）与兔黄体的结合情况，并研究了该类似物在垂体切除的假孕兔中的溶黄体活性。在假孕中期，给3只垂体切除并用雌激素处理的兔子每6小时皮下注射0.25 mg D - Ala，持续48小时，另外3只仅注射赋形剂。用D - Ala处理后，血清孕酮没有急性变化，黄体退化时间也未改变。发现兔垂体前叶组织含有高亲和力的GnRH受体（Ka = 7.0×10⁹ M⁻¹；188.2±35.6 fmol/mg蛋白）。然而，在假孕任何阶段的兔黄体组织中均未检测到类似的高亲和力GnRH受体。观察到一些明显的低亲和力结合，但随后在所有测试的对照组织中也观察到了这种可置换结合。因此，一种有效的GnRH类似物对兔黄体的类固醇生成没有任何可检测到的直接影响，兔黄体组织中也不存在高亲和力的GnRH结合位点。
