Shirasuna Koumei, Asaoka Hitomi, Acosta Tomas J, Wijayagunawardane Missaka P B, Matsui Motozumi, Ohtani Masayuki, Miyamoto Akio
Department of Agricultural and Life Science, Obihiro University of Agriculture andVeterinary Medicine, Japan.
J Cardiovasc Pharmacol. 2004 Nov;44 Suppl 1:S252-5. doi: 10.1097/01.fjc.0000166322.76376.60.
It is generally accepted that endothelin-1 (ET-1) is involved in the regression of the corpus luteum (CL) in cows, but there are few in vivo data available on the local release of vasoconstrictors, including ET-1. Thus, we aimed to determine in detail the local secretion of ET-1, angiotensin II (Ang II) and prostaglandin F2alpha (PGF2alpha) within the CL during spontaneous luteolysis in the cow. To observe real-time dynamics of the releasing profile of CL-derived factors, a microdialysis system was surgically implanted in the CL on day 15 of the estrous cycle and continuously perfused with Ringer's solution. Local secretion of ET-1, Ang II and PGF2alpha increased immediately after the onset of luteolysis (the time point when progesterone release started to decrease within the CL) and was maintained at high levels. A positive relationship was observed in intra-luteal changes among ET-1, Ang II and PGF2alpha release. This is the first real-time and in vivo evidence that the secretion of ET-1 together with Ang II and PGF2alpha immediately increases within the CL after the onset of spontaneous luteolysis. Consequently, we suggest that the activation of a local positive feedback mechanism among ET-1, Ang II and PGF2alpha might play a functional role in the paracrine modulation of luteolytic cascade and, simultaneously, the elevated ET-1 with Ang II and PGF2alpha should induce a strong vasoconstriction, thereby reducing the blood supplying the CL during spontaneous luteolysis.
一般认为，内皮素-1（ET-1）参与奶牛黄体（CL）的退化过程，但关于包括ET-1在内的血管收缩剂的局部释放，体内数据较少。因此，我们旨在详细确定奶牛自发黄体溶解过程中CL内ET-1、血管紧张素II（Ang II）和前列腺素F2α（PGF2α）的局部分泌情况。为了观察CL衍生因子释放曲线的实时动态，在发情周期第15天通过手术将微透析系统植入CL，并持续用林格氏液灌注。黄体溶解开始后（即CL内孕酮释放开始下降的时间点），ET-1、Ang II和PGF2α的局部分泌立即增加，并维持在高水平。在CL内ET-1、Ang II和PGF2α释放的变化之间观察到正相关关系。这是首次实时体内证据表明，自发黄体溶解开始后，CL内ET-1与Ang II和PGF2α的分泌立即增加。因此，我们认为ET-1、Ang II和PGF2α之间局部正反馈机制的激活可能在黄体溶解级联的旁分泌调节中发挥作用，同时，ET-1与Ang II和PGF2α水平升高应诱导强烈的血管收缩，从而在自发黄体溶解过程中减少供应CL的血液。
