Shirasuna Koumei, Asaoka Hitomi, Acosta Tomas J, Wijayagunawardane Missaka P B, Ohtani Masayuki, Hayashi Misato, Matsui Motozumi, Miyamoto Akio
Department of Agricultural and Life Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan.
Biol Reprod. 2004 Nov;71(5):1706-11. doi: 10.1095/biolreprod.104.030270. Epub 2004 Jul 21.
It is well known that prostaglandin F(2alpha) (PGF(2alpha)) is a physiological luteolysine, and that its pulsatile release from the endometrium is a luteolytic signal in many species. There is now clear evidence that the vasoactive peptides endothelin-1 (ET-1) and angiotensin II (Ang II) interact with PGF(2alpha) in the luteolytic cascade during PGF(2alpha)-induced luteolysis in the cow. Thus, we investigated the local secretion of PGF(2alpha), ET-1, and Ang II in the corpus luteum (CL) and their real-time relationships during spontaneous luteolysis in the cow. For this purpose, an in vivo microdialysis system (MDS) implanted in the CL was utilized to observe local secretion changes within the CL microenvironment. Each CL of cyclic Holstein cows (n = 6) was surgically implanted with MDS capillary membranes (18 lines/6 cows) on Day 15 (estrus = Day 0) of the estrous cycle. The concentrations of PGF(2alpha), ET-1, Ang II, and progesterone (P) in the MDS samples were determined by enzyme immunoassays. The intraluteal PGF(2alpha) secretion slightly increased from 12 h after the onset of luteolysis (0 h) and drastically increased (by about 300%) from 24 h. Intraluteal ET-1 secretion increased from 12 h. Intraluteal Ang II secretion was elevated from 0 h and was maintained at high levels (about 180%) toward estrus. In each MDS lines (in the same microenvironment) within the regressing CL, the local releasing profiles of PGF(2alpha), ET-1, and Ang II CL positively correlated with each other (P < 0.05) at high proportions in 18 MDS lines (PGF(2alpha) vs. ET-1, 44.4%; PGF(2alpha) vs. Ang II, 55.6%; ET-1 vs. Ang II, 38.9%). In contrast, there was no clear relationship among these substances released into different MDS lines implanted in the same CL (with different microenvironments). In conclusion, we propose that the increase of PGF(2alpha), ET-1, and Ang II within the CL during luteolysis is a common phenomenon for both PGF(2alpha)-induced and spontaneous luteolysis. Moreover, this study illustrated the in vivo relationships in intraluteal release among PGF(2alpha), ET-1, and Ang II during spontaneous luteolysis in the cow. The data suggest that these vasoactive substances may interact with each other in a local positive feedback manner to activate their secretion in the regressing CL, thus accelerating and completing luteolysis.
众所周知，前列腺素F(2α)（PGF(2α)）是一种生理性黄体溶解素，其从子宫内膜的脉冲式释放是许多物种中的黄体溶解信号。现在有明确证据表明，血管活性肽内皮素-1（ET-1）和血管紧张素II（Ang II）在奶牛PGF(2α)诱导的黄体溶解过程中的黄体溶解级联反应中与PGF(2α)相互作用。因此，我们研究了奶牛黄体（CL）中PGF(2α)、ET-1和Ang II的局部分泌及其在自发黄体溶解过程中的实时关系。为此，利用植入CL的体内微透析系统（MDS）来观察CL微环境内的局部分泌变化。在发情周期的第15天（发情日=第0天），对6头周期性荷斯坦奶牛的每个CL进行手术植入MDS毛细管膜（18根/6头奶牛）。通过酶免疫测定法测定MDS样品中PGF(2α)、ET-1、Ang II和孕酮（P）的浓度。黄体溶解开始后12小时（0小时），黄体内部PGF(2α)分泌略有增加，24小时后急剧增加（约300%）。黄体内部ET-1分泌从12小时开始增加。黄体内部Ang II分泌从0小时开始升高，并在接近发情期时维持在高水平（约180%）。在退化的CL内的每个MDS线（在相同微环境中），PGF(2α)、ET-1和Ang II的局部释放曲线在18个MDS线中的高比例下彼此呈正相关（P<0.05）（PGF(2α)与ET-1，44.4%；PGF(2α)与Ang II，55.6%；ET-1与Ang II，38.9%）。相比之下，释放到植入同一CL（具有不同微环境）的不同MDS线中的这些物质之间没有明显关系。总之，我们提出，黄体溶解期间CL内PGF(2α)、ET-1和Ang II的增加是PGF(2α)诱导的和自发黄体溶解的共同现象。此外，本研究阐明了奶牛自发黄体溶解期间PGF(2α)、ET-1和Ang II在黄体内部释放的体内关系。数据表明，这些血管活性物质可能以局部正反馈方式相互作用，以激活其在退化CL中的分泌，从而加速并完成黄体溶解。
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