Asselin E, Drolet P, Fortier M A
Département d'Ontogénie et Reproduction, Centre de Recherches du Centre Hospitalier de l'Université Laval, Ste-Foy, Québec, Canada.
Endocrinology. 1997 Nov;138(11):4798-805. doi: 10.1210/endo.138.11.5527.
PGs are important regulators of reproductive processes. At the time ofluteolysis in vivo, PGF2alpha is produced by endometrial cells, in response to oxytocin (OT). The mechanism by which OT induces the release of PGF2alpha remains to be defined. We have used 13 different cultures of bovine epithelial endometrial cells to study the effect of OT on the regulation of PGF2alpha and to identify the possible involvement of cyclooxygenases (COXs). OT induced a dose-dependent increase of both inositol phosphates (IPs) and [Ca2+]i concentration in epithelial cells labeled with [3H]-myoinositol or loaded with fura-2 (using a fluorescent microscope imaging system), respectively. OT induced a dose-dependent increase of both PGF2alpha production and COX-2 gene expression (as demonstrated by RT-PCR and Northern blots). PGF2alpha production was increased from 13.3 +/- 2.0 to 166.8 +/- 22.5 ng/ml (P < 0.0001). On the other hand, COX-2/beta-actin mRNA gene expression (as determined by densitometric analysis) was increased 5.1 +/- 0.7-fold (P < 0.001) with OT (10[-7] M) treatment, compared with control. Addition of indomethacin (1 microM) and a specific COX-2 inhibitor (NS-398, 1 microM) blocked the OT-induced PGF2alpha production. COX-1 and phospholipase A2 mRNA were expressed at steady-state levels, but no effect of OT was detected on their regulation. Combined to OT, 10 microq/ml of recombinant ovine interferon-tau (roIFN-tau) was able to decrease significantly (P < 0.0001) the dose-dependent increase of PGF2alpha production. Furthermore, partial bovine COX-1 (777 pb) and COX-2 (449 bp) cDNAs were cloned and sequenced. An homology of 83% and 97% was found in relation with rat and sheep, for COX-1, respectively. COX-2 was found to bear 84%, 86%, and 87% of homology in relation to rat, guinea pig, and human, respectively. Collectively, these results demonstrate, for the first time, that COX-2 is involved in the mechanism by which OT regulates PGF2alpha production in the endometrium.
前列腺素是生殖过程的重要调节因子。在体内黄体溶解时，子宫内膜细胞会响应催产素（OT）产生前列腺素F2α（PGF2α）。OT诱导PGF2α释放的机制尚待确定。我们使用了13种不同的牛子宫内膜上皮细胞培养物来研究OT对PGF2α调节的影响，并确定环氧化酶（COXs）可能的参与情况。OT分别在标记有[3H] - 肌醇的上皮细胞中或加载了fura - 2（使用荧光显微镜成像系统）的细胞中诱导了肌醇磷酸（IPs）和细胞内钙离子浓度（[Ca2+]i）的剂量依赖性增加。OT诱导了PGF2α产生和COX - 2基因表达的剂量依赖性增加（通过逆转录 - 聚合酶链反应（RT - PCR）和Northern印迹法证明）。PGF2α的产生从13.3±2.0增加到166.8±22.5 ng/ml（P < 0.0001）。另一方面，与对照组相比，OT（10[-7] M）处理后COX - 2/β - 肌动蛋白mRNA基因表达（通过光密度分析测定）增加了5.1±0.7倍（P < 0.001）。添加吲哚美辛（1 microM）和一种特异性COX - 2抑制剂（NS - 398，1 microM）可阻断OT诱导的PGF2α产生。COX - 1和磷脂酶A2 mRNA以稳态水平表达，但未检测到OT对它们调节的影响。与OT联合使用时，10 microq/ml的重组羊干扰素 - τ（roIFN - τ）能够显著降低（P < 0.0001）PGF2α产生的剂量依赖性增加。此外，克隆并测序了部分牛COX - 1（777 pb）和COX - 2（449 bp）的cDNA。分别发现COX - 1与大鼠和绵羊的同源性为83%和97%。发现COX - 2与大鼠、豚鼠和人类的同源性分别为84%、86%和87%。总体而言，这些结果首次证明COX - 2参与了OT调节子宫内膜中PGF2α产生的机制。
