Ansar Saema, Vikman Petter, Nielsen Marianne, Edvinsson Lars
Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, 221 84 Lund, Sweden.
Am J Physiol Heart Circ Physiol. 2007 Dec;293(6):H3750-8. doi: 10.1152/ajpheart.00857.2007. Epub 2007 Sep 14.
We hypothesize that cerebral ischemia leads to enhanced expression of endothelin (ET), 5-hydroxytryptamine (5-HT), and angiotensin II (ANG II) receptors in the vascular smooth muscle cells. Our aim is to correlate the upregulation of cerebrovascular receptors and the underlying molecular mechanisms with the reduction in regional and global cerebral blood flow (CBF) after subarachnoid hemorrhage (SAH). SAH was induced by injecting 250 microl blood into the prechiasmatic cistern in rats. The cerebral arteries were removed 0, 1, 3, 6, 12, 24, and 48 h after the SAH for functional and molecular studies. The contractile responses to ET-1, 5-carboxamidotryptamine (5-CT), and ANG II were investigated with myograph. The receptor mRNA and protein levels were analyzed by quantitative real-time PCR and immunohistochemistry, respectively. In addition, regional and global CBFs were measured by an autoradiographic method. As a result, SAH resulted in enhanced contractions to ET-1 and 5-CT. ANG II [via ANG II type 1 (AT(1)) receptors] induced increased contractile responses [in the presence of the ANG II type 2 (AT(2)) receptor antagonist PD-123319]. In parallel the ET(B), 5-HT(1B), and AT(1) receptor, mRNA and protein levels were elevated by time. The regional and global CBF showed a successive reduction with time after SAH. In conclusion, the results demonstrate for the first time that SAH induces the upregulation of ET(B), 5-HT(1B), and AT(1) receptors in a time-dependent manner both at functional, mRNA, and protein levels. These changes occur in parallel with a successive decrease in CBF. Thus there is a temporal correlation between the changes in receptor expression and CBF reduction, suggesting a linkage.
我们推测，脑缺血会导致血管平滑肌细胞中内皮素（ET）、5-羟色胺（5-HT）和血管紧张素II（ANG II）受体的表达增强。我们的目的是将蛛网膜下腔出血（SAH）后脑血管受体的上调及其潜在分子机制与局部和全脑血流量（CBF）的减少联系起来。通过向大鼠视交叉前池注射250微升血液诱导SAH。在SAH后的0、1、3、6、12、24和48小时移除脑动脉，用于功能和分子研究。用肌张力描记器研究对ET-1、5-羧酰胺色胺（5-CT）和ANG II的收缩反应。分别通过定量实时PCR和免疫组织化学分析受体mRNA和蛋白水平。此外，通过放射自显影法测量局部和全脑血流量。结果显示，SAH导致对ET-1和5-CT的收缩增强。ANG II [通过1型ANG II（AT(1)）受体]诱导收缩反应增加[在存在2型ANG II（AT(2)）受体拮抗剂PD-123319的情况下]。同时，ET(B)、5-HT(1B)和AT(1)受体的mRNA和蛋白水平随时间升高。SAH后局部和全脑血流量随时间连续减少。总之，结果首次证明SAH在功能、mRNA和蛋白水平上以时间依赖性方式诱导ET(B)、5-HT(1B)和AT(1)受体上调。这些变化与CBF的连续减少同时发生。因此，受体表达变化与CBF减少之间存在时间相关性，提示存在联系。
