Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden.
Department of Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet, Glostrup, Denmark.
Acta Ophthalmol. 2018 Aug;96(5):e619-e625. doi: 10.1111/aos.13651. Epub 2018 Jan 25.
Even though retinal vascular changes following ischaemia have been poorly understood, the upregulation of vasoconstrictive endothelin-1 (ET-1) receptors (ET /ET ) following global cerebral ischaemia has been described. The aim of this study was to investigate whether or not the MEK/ERK1/2 pathway is involved in the observed upregulation and whether specific MEK/ERK1/2 inhibitors U0126 and trametinib can prevent it.
The aim was also to localize ET and ET receptors using immunohistochemistry in both fresh rat ophthalmic arteries and after 24-hr organ culture and study the receptors functionally using myography. Pig retinal arteries also underwent 24-hr organ culture to validate similar responses across species and the retinal vasculature.
Results showed that following organ culture there is a significant increase in ET-1-mediated vasoconstriction, in particular via the ET receptor. Furthermore, immunohistochemistry revealed a clear increase in pERK in the smooth muscle cells of rat ophthalmic artery. U0126 and trametinib were successful in attenuating the functional vasoconstriction in both rat and pig, as well as restoring immunofluorescence of pERK to fresh levels and counteracting ET expression in the smooth muscle cells of the rat ophthalmic artery.
This is the first study to show that the MEK/ERK1/2 pathway in responsible for the increase in functional vasoconstriction via ET-1 receptor in rat ophthalmic and pig retinal arteries. Furthermore, this study is the first to suggest a way of inhibiting and preventing such an increase. With these results, we suggest a novel approach in retinal ischaemia therapy.
尽管缺血后视网膜血管变化尚未得到充分理解，但已描述了全脑缺血后血管收缩性内皮素-1（ET-1）受体（ET/ET）的上调。本研究旨在探讨 MEK/ERK1/2 途径是否参与观察到的上调，以及特定的 MEK/ERK1/2 抑制剂 U0126 和 trametinib 是否可以预防这种上调。
还旨在使用免疫组织化学在新鲜大鼠眼动脉和 24 小时器官培养后定位 ET 和 ET 受体，并使用肌动描记术研究受体的功能。猪视网膜动脉也进行了 24 小时器官培养，以验证跨物种和视网膜血管的类似反应。
结果表明，在器官培养后，ET-1 介导的血管收缩明显增加，特别是通过 ET 受体。此外，免疫组织化学显示大鼠眼动脉平滑肌细胞中 pERK 明显增加。U0126 和 trametinib 成功地减弱了大鼠和猪的功能性血管收缩，以及将 pERK 的免疫荧光恢复到新鲜水平，并在大鼠眼动脉平滑肌细胞中对抗 ET 表达。
这是第一项表明 MEK/ERK1/2 途径负责通过大鼠眼动脉和猪视网膜动脉中 ET-1 受体增加功能性血管收缩的研究。此外，这项研究首次提出了抑制和预防这种增加的方法。有了这些结果，我们提出了一种治疗视网膜缺血的新方法。
