Department of Pharmacology, Kinki University School of Medicine, Osaka, Japan.
Tohoku J Exp Med. 2009 Dec;219(4):331-6. doi: 10.1620/tjem.219.331.
Essential hypertension is a disease of unknown pathogenesis, although renal function has been implicated as an important factor in its cause. Stroke-prone spontaneously hypertensive (SHRSP) rats provide an animal model of essential hypertension. To understand the cause of hypertension, identifying proteins that are differentially expressed between hypertensive and normotensive rats may provide a key. Here, proteins in the renal cortex from SHRSP rats, malignant stroke-prone spontaneously hypertensive (M-SHRSP) rats, and Wistar Kyoto (WKY) rats as a normotensive control were subjected to two-dimensional difference gel electrophoresis (2D-DIGE). After in-gel digestion by trypsin, proteins were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Several proteins showed differential expression patterns between hypertensive and normotensive rats. Among them, we focused on catechol-O-methyltransferase (COMT) because this enzyme inactivates catecholamines, possibly affecting blood pressure. To confirm the differential expression of COMT in each animal, we conducted Western blot analysis, which revealed that the expression of COMT is lower in M-SHRSP rats than in control and SHRSP rats, indicating that blood pressure and expression of COMT are related. In fact, the blood pressure of M-SHRSP rats was significantly higher than that of SHRSP rats at age of 10 weeks. Immunohistochemical and immunofluorescence studies showed that COMT in renal cortex is localized in tubular epithelial cells. The expression of COMT is lower in the renal cortex tubular epithelium of M-SHRSP rats than in normotensive rats. These results suggest that the decreased expression of COMT may be an important factor leading to the development of hypertension.
原发性高血压是一种病因不明的疾病，尽管肾功能已被认为是其病因的一个重要因素。易发生卒中的自发性高血压（SHRSP）大鼠为原发性高血压提供了一种动物模型。为了了解高血压的病因，鉴定高血压大鼠和正常血压大鼠之间差异表达的蛋白质可能是一个关键。在这里，我们对 SHRSP 大鼠、恶性易发生卒中的自发性高血压（M-SHRSP）大鼠和 Wistar Kyoto（WKY）大鼠的肾皮质中的蛋白质进行了二维差异凝胶电泳（2D-DIGE）。用胰蛋白酶进行胶内消化后，用基质辅助激光解吸/电离飞行时间质谱（MALDI-TOFMS）鉴定蛋白质。几种蛋白质在高血压大鼠和正常血压大鼠之间表现出不同的表达模式。其中，我们重点关注儿茶酚-O-甲基转移酶（COMT），因为这种酶使儿茶酚类物质失活，可能影响血压。为了证实 COMT 在每种动物中的差异表达，我们进行了 Western blot 分析，结果表明 M-SHRSP 大鼠的 COMT 表达低于对照和 SHRSP 大鼠，表明血压和 COMT 的表达相关。事实上，M-SHRSP 大鼠的血压在 10 周龄时明显高于 SHRSP 大鼠。免疫组织化学和免疫荧光研究表明，肾皮质中的 COMT 定位于肾小管上皮细胞。M-SHRSP 大鼠肾皮质的 COMT 表达低于正常血压大鼠。这些结果表明，COMT 的表达降低可能是导致高血压发展的一个重要因素。
