Tamura Jun, Konno Akihiro, Hashimoto Yoshiharu, Kon Yasuhiro
Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
Jpn J Vet Res. 2005 Aug;53(1-2):13-26.
The aim of this study was to clarify the role of the renal renin-angiotensin system (RAS) in diabetic nephropathy (DN), which was induced by injection of streptozotocin (STZ). Male CBA/N and CBA/J mice were compared in this study. The former possesses a single renin gene, Ren1, whereas the latter carries two renin genes, Ren1 and Ren2. To examine the molecular dynamics of renal RAS, including renin, angiotensinogen (Agt), angiotensin-converting enzyme (Ace), angiotensin type 1 (Agtr1) and type 2 (Agtr2) receptors in experimental DN, we performed laser-microdissection (LMD) followed by reverse transcriptase nested polymerase chain reaction using each specific primer pairs and immunohistochemistry for renin and angiotensin II. CBA/N mice had a higher response after injection of STZ than CBA/J mice, showing a significant increase of the kidney/body weight ratio, although there was no significant difference between the two strains for the blood glucose level or pancreatic beta-cell response. The onset of renal pathological changes associated with DN was earlier and more severe in CBA/N mice than in CBA/J mice. Distinct immunoreactivities for renin and angiotensin II were newly distributed on the flattened epithelial cells in the dilated distal tubules in the cortex as well as the collecting ducts in the cortex and medulla, and were demonstrated more intensely in CBA/N mice than in CBA/J mice. Microdissectional analysis in both DN models revealed a higher incidence of RAS-related gene expression in CBA/J, Ren 1 Ren 2 mice than in CBA/N, Ren 1 mice. These findings suggest that intrarenal RAS plays an important role in the onset of renal pathological changes associated with DN. Additionally, Ren 1 mice have more severe histopathological nephropathy than Ren1 Ren2 mice, followed by marked production of angiotensin II.
本研究的目的是阐明肾脏肾素 - 血管紧张素系统（RAS）在由注射链脲佐菌素（STZ）诱导的糖尿病肾病（DN）中的作用。本研究比较了雄性CBA/N和CBA/J小鼠。前者拥有单一的肾素基因Ren1，而后者携带两个肾素基因Ren1和Ren2。为了研究实验性DN中肾脏RAS的分子动力学，包括肾素、血管紧张素原（Agt）、血管紧张素转换酶（Ace）、血管紧张素1型（Agtr1）和2型（Agtr2）受体，我们进行了激光显微切割（LMD），随后使用每种特异性引物对进行逆转录巢式聚合酶链反应，并对肾素和血管紧张素II进行免疫组织化学分析。注射STZ后，CBA/N小鼠比CBA/J小鼠有更高的反应，表现为肾重/体重比显著增加，尽管两品系之间的血糖水平或胰腺β细胞反应没有显著差异。与DN相关的肾脏病理变化在CBA/N小鼠中比在CBA/J小鼠中出现得更早且更严重。肾素和血管紧张素II的明显免疫反应性新分布在皮质扩张的远端小管以及皮质和髓质的集合管中的扁平上皮细胞上，并且在CBA/N小鼠中比在CBA/J小鼠中表现得更强烈。在两种DN模型中的显微切割分析显示，与CBA/N（Ren 1）小鼠相比，CBA/J（Ren 1 Ren 2）小鼠中RAS相关基因表达的发生率更高。这些发现表明，肾内RAS在与DN相关的肾脏病理变化的发生中起重要作用。此外，Ren 1小鼠比Ren1 Ren2小鼠有更严重的组织病理学肾病，随后是血管紧张素II的大量产生。
