Tamby J P, Reinaud P, Charpigny G
Station de Physiologie Animale, INRA, Jouy-en-Josas, France.
J Reprod Fertil. 1996 May;107(1):23-30. doi: 10.1530/jrf.0.1070023.
In sheep, the pulsatile release of prostaglandin F2 alpha by the endometrium is necessary to achieve luteolysis which occurs at the end of the oestrous cycle. The production of prostaglandins is known to depend upon the availability of arachidonic acid, the fatty acid precursor of prostaglandin biosynthesis. Consequently, the mechanisms controlling intracellular amounts of arachidonate may be involved in the regulation of prostaglandin synthesis. Since arachidonic acid is mostly found in phospholipids and the endometrial epithelium is the primary source of prostaglandin F2 alpha during luteolysis, the fate of arachidonic acid when incorporated into epithelial cells from the ovine uterus was investigated. Endometrial epithelial cells isolated from cyclic ewes at day 15 after oestrus were cultured in the presence of [3H]arachidonic acid. Incorporation and distribution of the radiolabelled arachidonic acid into the various phospholipid classes were examined using HPLC. We observed that ethanolamine glycerophospholipids contained 61% of the total tritiated arachidonic acid incorporated into cellular lipids, whereas phosphatidylinositols, phosphatidylcholines and phosphatidylserines contained 17%, 13% and 4.7%, respectively. In addition, the radioactivity measured within phosphatidylethanolamines was preferentially detected in the 1-alkenyl-2-acyl (44%) forms of ethanolamine phospholipids, also called plasmalogens. The kinetic study of arachidonic acid uptake into ethanolamine phospholipids showed that arachidonic acid was rapidly esterified into the diacyl forms and then uptake decreased, whereas the incorporation increased continuously into the plasmalogen forms for at least 24 h. These results demonstrate that the primary pool of esterified arachidonic acid is found in ethanolamine plasmalogens of epithelial cells from the ovine endometrium. The high arachidonate content of ethanolamine plasmalogens suggests that these phospholipids play a crucial role in the control of arachidonic acid availability and ultimately in the regulation of prostaglandin synthesis.
在绵羊中，子宫内膜脉冲式释放前列腺素F2α对于在发情周期末期发生的黄体溶解是必需的。已知前列腺素的产生取决于花生四烯酸的可用性，花生四烯酸是前列腺素生物合成的脂肪酸前体。因此，控制细胞内花生四烯酸含量的机制可能参与前列腺素合成的调节。由于花生四烯酸主要存在于磷脂中，并且在黄体溶解期间子宫内膜上皮是前列腺素F2α的主要来源，因此研究了花生四烯酸从绵羊子宫掺入上皮细胞后的命运。在发情后第15天从周期性母羊分离的子宫内膜上皮细胞在[3H]花生四烯酸存在下培养。使用高效液相色谱法检查放射性标记的花生四烯酸掺入各种磷脂类别的情况。我们观察到，乙醇胺甘油磷脂含有掺入细胞脂质中的总氚化花生四烯酸的61%，而磷脂酰肌醇、磷脂酰胆碱和磷脂酰丝氨酸分别含有17%、13%和4.7%。此外，在磷脂酰乙醇胺中测得的放射性优先在乙醇胺磷脂的1-烯基-2-酰基（44%）形式中检测到，也称为缩醛磷脂。花生四烯酸摄取到乙醇胺磷脂中的动力学研究表明，花生四烯酸迅速酯化为二酰基形式，然后摄取减少，而缩醛磷脂形式的掺入至少持续24小时持续增加。这些结果表明，酯化花生四烯酸的主要库存在于绵羊子宫内膜上皮细胞的乙醇胺缩醛磷脂中。乙醇胺缩醛磷脂的高花生四烯酸含量表明这些磷脂在控制花生四烯酸可用性以及最终在前列腺素合成调节中起关键作用。
