血管紧张素1a型受体基因敲除小鼠肾脏局部肾素-血管紧张素系统的变化及其对糖尿病肾小球硬化的影响

目的 探讨血管紧张素1a型受体（AT1aR）基因敲除小鼠肾脏局部肾素-血管紧张素系统（RAS）的组分改变对糖尿病肾病（DN）肾小球硬化的影响及其可能机制。 方法 AT1aR基因敲除小鼠和野生型小鼠腹腔注射链脲佐菌素（STZ，300 mg/kg）诱导糖尿病模型12周后，取肾脏组织作冰冻组织切片，用激光捕获微切割技术分离肾小球，提取RNA。用实时定量PCR的方法检测肾小球内AT1aR、血管紧张素1b型受体（AT1bR）、血管紧张素2型受体（AT2R）、血管紧张素原、血管紧张素转化酶（ACE）、肾素、醛固酮合成酶（CYP11B2）的mRNA表达。PAS染色观察肾脏病理变化。免疫组化检测转化生长因子β1（TGF-β1）、1型纤溶酶原激活物抑制物(PAI-1)、单核细胞趋化因子1(MCP-1)和肾素的表达。比较不同基因型小鼠肾小球细胞外基质和各细胞因子的表达变化。 结果 与野生型小鼠相比，AT1aR基因敲除小鼠肾小球内AT1bR、血管紧张素原、肾素、CYP11B2的表达明显上调（P < 0.05），AT2R表达下调，ACE无明显改变；AT1aR基因敲除小鼠肾小球细胞外基质明显增加（P < 0.05），TGF-β1、PAI-1、MCP-1和肾素的表达均明显增加（P < 0.05）。 结论 AT1aR基因敲除并不能使糖尿病小鼠肾脏病变改善。RAS组分的表达改变（AT1bR的上调和AT2 的下调，肾素的上调和CYP11B2的上调）参与糖尿病肾小球病变过程。

Change of glomerular renin-angiotensin system expression in angiotensin type 1a receptor gene knockout mice and its effects on extracellular matrix remodeling under diabetic condition

Objective To explore the glomerular change of renin-angiotensin system (RAS) expression in ATIaR gene knockout mice and its effects on extracellular matrix (ECM) remodeling under diabetic condition. Methods ATlaR knockout mice were generated previously. Hyperglycemia was induced by peritoneal injection of streptozotocin in ATIaR knockout mice and wild type mice. Normal AT1aR knockout mice and wild type mice were used as control group. Twelve weeks later, kidneys were harvested and frozen quickly in dry ice-acetone. Glomendi were collected by laser capture microdissection and total RNA was extracted, mRNA expression of AT1aR, AT1bR, AT2R, angiotensinogen, ACE, renin, and CYP11B2 was assessed by real-time PCR. ECM accumulation was evaluated by PAS staining. Protein levels of transforming growth factor β1(TGF-β1), type 1 plasminogen activator inhibitor(PAI-1), monocyte chemotactie protein 1(MCP-1) and renin were semi-quantitated by immunostaining. Results Compared to the wild type, mRNA expression of AT1bR, angiotensinogen, renin, CYP11B2 within glomeruli was upregulated significantly in ATlaR knockout mice (P<0.05), but no change of ACE expression was found in these two groups. AT2R protein was poorly detected in AT1aR knockout glomeruli and downregulated in wild type glomemli. ECM accumulation was significanfly increased associated with the parallel increase in TGF-β1, PAI-1, MCP-1 and renin within glomendi (P <0.05). Conclusions AT1aR gene knockout cannot improve ECM deposition in diabetic nephropathy. The compensate change of RAS components may be involved in this scenario: upregulation of AT1bR, downregulation of AT2R. CYP11B2 and renin may function in a novel pathway.