Kim S, Kawamura M, Wanibuchi H, Ohta K, Hamaguchi A, Omura T, Yukimura T, Miura K, Iwao H
Department of Pharmacology, Osaka City University Medical School, Japan.
Circulation. 1995 Jul 1;92(1):88-95. doi: 10.1161/01.cir.92.1.88.
Vascular injury activates various kinds of genes, including proto-oncogenes, growth factors, and extracellular matrix proteins. However, the significance of activation of these genes in neointimal formation is poorly understood. Angiotensin II type 1 (AT1) receptor antagonist is shown to prevent neointimal formation after vascular injury, although the mechanism is unclear. To understand the molecular mechanism of vascular thickening, we examined the effects of AT1 receptor blockade on the gene expression of proto-oncogenes, transforming growth factor-beta 1 (TGF-beta 1), and extracellular matrix proteins after vascular injury.
Endothelial denudation of the left common carotid artery in Sprague-Dawley rats was performed with a Fogarty 2F balloon catheter. TCV-116 (10 mg.kg-1.d-1), a selective nonpeptide AT1 receptor antagonist, or vehicle was administered orally to rats from 1 day before to 14 days after balloon injury. Injured left and uninjured right common carotid arteries were removed from rats at 1, 6, and 24 hours and 3, 7, and 14 days after balloon injury. Tissue mRNA levels were measured with Northern blot analysis using specific cDNA probes and corrected for 18S ribosomal RNA value. Arterial mRNAs for c-fos, c-jun, jun B, jun D, and Egr-1 increased significantly at 1 hour after balloon injury and decreased rapidly. At 6 hours, ornithine decarboxylase (ODC) mRNA expression reached the maximal levels. TGF-beta 1 and fibronectin mRNA levels started to increase at 6 hours after injury and remained enhanced until 7 days after injury. On the other hand, collagen types I, III, and IV and laminin mRNA levels were not significantly increased over 7 days. Treatment with TCV-116 significantly inhibited the induction of mRNAs for c-fos, c-jun, Egr-1, ODC, and fibronectin in injured artery, whereas the increase in TGF-beta 1 gene expression after injury was not prevented by TCV-116. Immunohistological studies indicated that TCV-116 decreased not only the intimal thickening but also the amount of these extracellular matrix proteins in the intima.
The results indicate that AT1 receptor blockade inhibits the induction of immediate-early genes, ODC, and fibronectin in rat injured artery. Thus, inhibition of intimal thickening by AT1 receptor blockade may be mediated at least in part by suppression of multiple genes related to cell growth and migration in the very early phase after vascular injury.
血管损伤可激活多种基因，包括原癌基因、生长因子和细胞外基质蛋白。然而，这些基因的激活在新生内膜形成中的意义尚不清楚。血管紧张素II 1型（AT1）受体拮抗剂虽机制不明，但已证实可预防血管损伤后的新生内膜形成。为了解血管增厚的分子机制，我们研究了AT1受体阻断对血管损伤后原癌基因、转化生长因子-β1（TGF-β1）和细胞外基质蛋白基因表达的影响。
用Fogarty 2F球囊导管对Sprague-Dawley大鼠的左颈总动脉进行内皮剥脱。从球囊损伤前1天至损伤后14天，给大鼠口服选择性非肽类AT1受体拮抗剂TCV-116（10mg·kg-1·d-1）或赋形剂。在球囊损伤后1、6和24小时以及3、7和14天，从大鼠身上取出受伤的左颈总动脉和未受伤的右颈总动脉。用特异性cDNA探针通过Northern印迹分析测量组织mRNA水平，并根据18S核糖体RNA值进行校正。球囊损伤后1小时，动脉中c-fos、c-jun、jun B、jun D和Egr-1的mRNA水平显著升高，随后迅速下降。在6小时时，鸟氨酸脱羧酶（ODC）mRNA表达达到最高水平。TGF-β1和纤连蛋白mRNA水平在损伤后6小时开始升高，并一直持续到损伤后7天。另一方面，I、III和IV型胶原蛋白以及层粘连蛋白mRNA水平在7天内未显著升高。用TCV-116治疗可显著抑制损伤动脉中c-fos、c-jun、Egr-1、ODC和纤连蛋白mRNA的诱导，而TCV-116不能阻止损伤后TGF-β1基因表达的增加。免疫组织学研究表明，TCV-116不仅减少了内膜增厚，还减少了内膜中这些细胞外基质蛋白的含量。
结果表明，AT1受体阻断可抑制大鼠损伤动脉中即早基因、ODC和纤连蛋白的诱导。因此，AT1受体阻断对内膜增厚的抑制作用可能至少部分是通过在血管损伤后极早期抑制与细胞生长和迁移相关的多个基因来介导的。
