Zerani M, Dall'Aglio C, Maranesi M, Gobbetti A, Brecchia G, Mercati F, Boiti C
Dipartimento di Biologia Molecolare, Cellulare e Animale, Università di Camerino, via F Camerini 1, Camerino, Italy.
Reproduction. 2007 May;133(5):1005-16. doi: 10.1530/REP-06-0107.
The objective of the present study was to investigate in rabbit corpora lutea (CL), at both the cellular and molecular level, intraluteal cyclooxygenase (COX)-1, COX-2 and prostaglandin (PG) E2-9-ketoreductase (PGE2-9-K) enzymatic activities as well as in vitro PGE2 and PGF2alpha synthesis following PGF2alpha treatment at either early- (day-4) or mid-luteal (day-9) stage of pseudopregnancy. By immunohistochemistry, positive staining for COX-2 was localized in luteal and endothelial cells of stromal arteries at both the stages. In CL of both stages, basal COX-2 mRNA levels were poorly expressed, but rose (P < 0.01) 4- to 10-fold 1.5-6 h after treatment and then gradually decreased within 24 h. Compared to mid-stage, day-4 CL had lower (P < 0.01) COX-2 and PGE2-9-K basal activities, and PGF2alpha synthesis rate, but higher (P < 0.01) PGE2 production. Independent of luteal stage, PGF2alpha treatment did not affect COX-1 activity. In day-4 CL, PGF2alpha induced an increase (P < 0.01) in both COX-2 activity and PGF2alpha synthesis, whereas that of PGE2 remained unchanged. In day-9 CL, PGF2alpha up-regulated (P < 0.01) both COX-2 and PGE-9-K activities, and PGF2alpha production, but decreased (P < 0.01) PGE2 synthesis. All changes in gene expression and enzymatic activities occurred within 1.5 h after PGF2alpha challenge and were more marked in day-9 CL. Our data suggest that PGF2alpha directs intraluteal PG biosynthesis in mature CL, by affecting the CL biosynthetic machinery to increase the PGF2alpha synthesis in an auto-amplifying manner, with the activation of COX-2 and PGE-9-K; this may partly explain their differentially, age-dependent, luteolytic capacity to exogenous PGF2alpha in rabbits.
本研究的目的是在细胞和分子水平上，研究假孕早期（第4天）或中期（第9天）给予前列腺素F2α（PGF2α）处理后，兔黄体（CL）中黄体内环氧合酶（COX）-1、COX-2和前列腺素（PG）E2-9-酮还原酶（PGE2-9-K）的酶活性，以及体外PGE2和PGF2α的合成。通过免疫组织化学方法，两个阶段的COX-2阳性染色均定位于黄体和间质动脉的内皮细胞。在两个阶段的黄体中，基础COX-2 mRNA水平表达较低，但在处理后1.5-6小时上升（P<0.01）4至10倍，然后在24小时内逐渐下降。与中期相比，第4天的黄体COX-2和PGE2-9-K基础活性以及PGF2α合成率较低（P<0.01），但PGE2产生较高（P<0.01）。与黄体阶段无关，PGF2α处理不影响COX-1活性。在第4天的黄体中，PGF2α诱导COX-2活性和PGF2α合成增加（P<0.01），而PGE2的合成保持不变。在第9天的黄体中，PGF2α上调（P<0.01）COX-2和PGE-9-K活性以及PGF2α产生，但降低（P<0.01）PGE2合成。PGF2α刺激后1.5小时内，基因表达和酶活性的所有变化均发生，且在第9天的黄体中更为明显。我们的数据表明，PGF2α通过影响黄体生物合成机制，以自放大方式增加PGF2α合成，激活COX-2和PGE-9-K，从而指导成熟黄体中的黄体内PG生物合成；这可能部分解释了它们对兔外源性PGF2α的不同年龄依赖性黄体溶解能力。
