Enhanced expressions of microvascular smooth muscle receptors after focal cerebral ischemia occur via the MAPK MEK/ERK pathway
Enhanced expressions of microvascular smooth muscle receptors after focal cerebral ischemia occur via the MAPK MEK/ERK pathway
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DOI：
10.1186/1471-2202-9-85
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发表时间：
2008-09-15
期刊：
影响因子：
2.4
通讯作者：
Edvinsson, Lars
中科院分区：
文献类型：
--
作者：
Maddahi, Aida;Edvinsson, Lars
背景：MEK1/2是一种丝氨酸/苏氨酸蛋白，可磷酸化细胞外信号调节激酶(ERK1/2)。脑缺血导致大脑中动脉(MCA)脑血管收缩受体表达增强，导致缺血区。方法与结果：大鼠大脑中动脉闭塞(MCAO)2 h后再灌流48 h，计算缺血面积。应用免疫组织化学共聚焦显微镜技术检测脑血管、微血管和脑组织中磷酸化ERK1/2和ELK-1、内皮素ETA和ETB、血管紧张素转换酶AT(1)和5-羟色胺5-HT1B受体的表达。用定量Western印迹法检测内皮素ETB受体的表达。我们证明，在大脑中动脉和缺血区的微血管中，收缩的平滑肌受体的数量增加。共定位研究证实，增强的表达发生在平滑肌细胞中。这种受体的上调还与血管平滑肌细胞中pERK1/2和转录因子pElk-1的表达增强有关。用MEK1抑制剂U0126阻断转录，在再灌流开始或损伤后6h，可降低转录(pERK1/2和pElk-1)，增强血管受体的表达，减轻脑梗塞，改善神经功能评分。结论：MCAO导致脑血管ETB、AT(1)和5-HT1B受体表达上调。在损伤后6h用MEK1抑制剂阻断这一事件可减少血管受体表达的增强和相关的脑梗塞。
Background: MEK1/2 is a serine/threonine protein that phosphorylates extracellular signal-regulated kinase (ERK1/2). Cerebral ischemia results in enhanced expression of cerebrovascular contractile receptors in the middle cerebral artery (MCA) leading to the ischemic region. Here we explored the role of the MEK/ERK pathway in receptor expression following ischemic brain injury using the specific MEK1 inhibitor U0126.Methods and result: Rats were subjected to a 2-h middle cerebral artery occlusion (MCAO) followed by reperfusion for 48-h and the ischemic area was calculated. The expression of phosphorylated ERK1/2 and Elk-1, and of endothelin ETA and ETB, angiotensin AT(1), and 5-hydroxytryptamine 5-HT1B receptors were analyzed with immunohistochemistry using confocal microscopy in cerebral arteries, microvessels and in brain tissue. The expression of endothelin ETB receptor was analyzed by quantitative Western blot. We demonstrate that there is an increase in the number of contractile smooth muscle receptors in the MCA and in micro- vessels within the ischemic region. The enhanced expression occurs in the smooth muscle cells as verified by colocalization studies. This receptor upregulation is furthermore associated with enhanced expression of pERK1/2 and of transcription factor pElk-1 in the vascular smooth muscle cells. Blockade of transcription with the MEK1 inhibitor U0126, given at the onset of reperfusion or as late as 6 hours after the insult, reduced transcription (pERK1/2 and pElk-1), the enhanced vascular receptor expression, and attenuated the cerebral infarct and improved neurology score.Conclusion: Our results show that MCAO results in upregulation of cerebrovascular ETB, AT(1) and 5-HT1B receptors. Blockade of this event with a MEK1 inhibitor as late as 6 h after the insult reduced the enhanced vascular receptor expression and the associated cerebral infarction.