Durieu-Trautmann O, Fédérici C, Créminon C, Foignant-Chaverot N, Roux F, Claire M, Strosberg A D, Couraud P O
Laboratoire d'Immuno-Pharmacologie Moléculaire, CNRS UPR 0415, Université Paris VII, ICGM, France.
J Cell Physiol. 1993 Apr;155(1):104-11. doi: 10.1002/jcp.1041550114.
Endothelin (ET)-1 was originally characterized as a potent vasoconstrictor peptide secreted by vascular endothelial cells. It possesses a wide range of biological activities within the cardiovascular system and in other organs, including the brain. Also secreted by endothelial cells, nitric oxide (NO), has recently been identified as a relaxing factor, as well as a pleiotropic mediator, second messenger, immune defence molecule, and neurotransmitter. Most of the data concerning the secretion of these two agents in vitro has been collected from studies on macrovascular endothelial cells. Given the remarkable heterogeneity of endothelia in terms of morphology and function, we have analyzed the ability of brain microvessel endothelial cells in vitro to release ET-1 and NO, which, at the level of the blood-brain barrier, have perivascular astrocytes as potential targets. The present study was performed with immortalized rat brain microvessel endothelial cells, which display in culture a non transformed phenotype. Our data demonstrate that: (1) these cells release NO when induced by IFN gamma and TNF alpha, (2) they constitutively secrete ET-1, and (3) cAMP potentiates the cytokine-induced NO release and exerts a biphasic regulation on ET-1 secretion: micromolar concentrations of 8-Br-cAMP inhibit and higher doses stimulate ET-1 secretion. This stimulation is blocked by EGTA and the calmodulin antagonist W7, but not by protein kinase C inhibitors, suggesting the involvement of the calmodulin branch of the calcium messenger system. These results suggest that cerebral microvessel endothelial cells may participate in vivo to the regulation of glial activity in the brain through the release of NO and ET-1.
内皮素（ET）-1最初被鉴定为血管内皮细胞分泌的一种强力血管收缩肽。它在心血管系统以及包括脑在内的其他器官中具有广泛的生物活性。同样由内皮细胞分泌的一氧化氮（NO），最近被确定为一种舒张因子，也是一种多效性介质、第二信使、免疫防御分子和神经递质。关于这两种物质体外分泌的大多数数据是从对大血管内皮细胞的研究中收集的。鉴于内皮细胞在形态和功能方面具有显著的异质性，我们分析了脑微血管内皮细胞在体外释放ET-1和NO的能力，在血脑屏障水平，血管周围星形胶质细胞是它们潜在的作用靶点。本研究使用永生化大鼠脑微血管内皮细胞进行，这些细胞在培养中表现出未转化的表型。我们的数据表明：（1）这些细胞在受到γ干扰素和肿瘤坏死因子α诱导时释放NO，（2）它们组成性地分泌ET-1，（3）环磷酸腺苷（cAMP）增强细胞因子诱导的NO释放，并对ET-1分泌发挥双相调节作用：微摩尔浓度的8-溴-cAMP抑制ET-1分泌，而更高剂量则刺激其分泌。这种刺激被乙二醇双乙胺醚四乙酸（EGTA）和钙调蛋白拮抗剂W7阻断，但不被蛋白激酶C抑制剂阻断，提示钙信使系统的钙调蛋白分支参与其中。这些结果表明，脑微血管内皮细胞可能在体内通过释放NO和ET-1参与对脑内神经胶质细胞活性的调节。
