Arioua R K, Féral C, Benhaïm A, Delarue B, Leymarie P
Laboratoire de Biochimie, EP CNRS 9, CHU Côte de Nacre, Caen, France.
J Endocrinol. 1997 Aug;154(2):249-57. doi: 10.1677/joe.0.1540249.
It is well established that the rabbit corpus luteum (CL) function depends upon endogenous oestradiol, the major source of which in the rabbit ovary is considered to be the ovarian follicles. The absence of oestradiol formation by the rabbit CL has been previously reported. In a hyperstimulated pseudopregnant rabbit model used in our laboratory which developed a large number of corpora lutea in response to chorionic gonadotrophin (eCG)/hCG, we observed the survival of corpora lutea in vivo, and normal levels of plasma progesterone throughout pseudopregnancy (PP), despite the scarcity or the absence of follicles as a source of the luteotrophic hormone. Measurement of oestradiol in the plasma indicated that it was at high levels and correlated with the number of corpora lutea. This led us to investigate the luteal origin of oestradiol in this model. PP was induced in rabbits by i.m. injection of 200 IU eCG daily for 2 days followed on day 4 by i.m. injection of 200 IU hCG (day 0 of PP). Luteal tissue obtained at days 5, 9 and 12 of PP and cultured for 24 h synthesized oestradiol and testosterone in addition to progesterone. However, under the same conditions, follicles had limited capacity to secrete oestradiol. The presence of an aromatase activity in luteal tissue was confirmed when exogenous testosterone was added to the culture medium. P450aromatase (P450arom) mRNA was found in luteal tissue at days 5, 9 and 12 of PP. Small or large luteal cells, obtained by enzymatic digestion of the tissue followed by centrifugation in a Percoll density gradient, were cultured during several days with or without gonadotrophin or dibutyryl cAMP (dbcAMP). Both types of cells secreted oestradiol. In small cells and luteal tissue, aromatase activity was stimulated (1.5-2-fold) by hCG and dbcAMP. Large cells exhibited a greater capacity to aromatize testosterone than small cells, but aromatase activity was not modified by hCG or by dbcAMP. FSH had no effect on aromatase activity of either luteal cell type. This intrinsic luteal tissue aromatase capacity and the absence of premature regression of corpora lutea despite the limited support of follicular oestrogen, suggest an autocrine and luteotrophic role for this luteal oestrogen.
众所周知，兔黄体（CL）功能依赖于内源性雌二醇，而兔卵巢中雌二醇的主要来源被认为是卵泡。此前已有报道称兔黄体无法形成雌二醇。在我们实验室使用的超刺激假孕兔模型中，该模型因绒毛膜促性腺激素（eCG）/人绒毛膜促性腺激素（hCG）刺激而产生大量黄体，我们观察到黄体在体内的存活情况，并且在整个假孕（PP）期间血浆孕酮水平正常，尽管作为黄体生成素来源的卵泡稀少或不存在。血浆中雌二醇的测量表明其处于高水平，且与黄体数量相关。这促使我们研究该模型中雌二醇的黄体来源。通过肌肉注射每天200 IU eCG，连续注射2天，随后在第4天肌肉注射200 IU hCG（PP第0天）来诱导兔假孕。在PP第5、9和12天获取黄体组织并培养24小时，其除了合成孕酮外，还合成雌二醇和睾酮。然而，在相同条件下，卵泡分泌雌二醇的能力有限。当向培养基中添加外源性睾酮时，证实了黄体组织中存在芳香化酶活性。在PP第5、9和12天的黄体组织中发现了细胞色素P450芳香化酶（P450arom）mRNA。通过酶消化组织，然后在Percoll密度梯度中离心获得的小或大黄体细胞，在有或没有促性腺激素或二丁酰环磷腺苷（dbcAMP）的情况下培养数天。两种类型的细胞均分泌雌二醇。在小细胞和黄体组织中，hCG和dbcAMP刺激芳香化酶活性（1.5至2倍）。大细胞比小细胞具有更强的睾酮芳香化能力，但hCG或dbcAMP对芳香化酶活性没有影响。促卵泡激素（FSH）对两种黄体细胞类型的芳香化酶活性均无影响。这种黄体组织固有的芳香化酶能力以及尽管卵泡雌激素支持有限但黄体未过早退化，表明这种黄体雌激素具有自分泌和黄体营养作用。
