缬沙坦对高糖上调系膜细胞细胞外调节蛋白激酶表达的影响

目的观察在高糖刺激下，系膜细胞细胞外调节蛋白激酶（ERKI／2）的活性变化以及缬沙坦对其影响，探讨缬沙坦保护肾脏作用的可能机制。方法原代培养大鼠肾脏系膜细胞，随机分为4组：低糖组（NG，d-葡萄糖5．5mmol／L）、高糖组（HG，d-葡萄糖30mmol／L）、甘露醇组（MG，d-葡萄糖5．5mmol／L＋甘露醇24．5mmol／L）和缬沙坦组（HG＋Val，d-葡萄糖30mmol／L＋缬沙坦10μmol／L）。用免疫细胞化学法及Western印迹法对系膜细胞中磷酸化ERK1／2（p-ERK1／2）的表达进行定位及半定量分析；RT—PCR法检测细胞中TGF-β1 mRNA的表达；放射免疫法测定各组细胞上清中Ⅳ型胶原的含量。结果高糖组系膜细胞中P-ERK1／2蛋白的表达较低糖组明显增高，并由胞质向胞核内转移，呈时间依赖方式（P〈0．01）；TGF-β1 mRNA及细胞上清液中Ⅳ型胶原水平均高于低糖组（P〈0．01）。而缬沙坦组上述指标均较同时相点高糖组显著降低，差异有统计学意义（P〈0．01）。甘露醇组与低糖组各指标间差异均无统计学意义。结论高糖可显著激活系膜细胞ERK信号通路，缬沙坦可抑制高糖的激活作用。

Effect of valsartan on up-regulating expression of ERK induced by high glucose in glomerular mesangial cells

Objective To observe the activity of extracellular signal-regulated kinase（ERK） in glomerular mesangial cells（GMC）exposed to high glucose and the effect of valsartan on ERK activity, and explore the possible renoprotection mechanism of valsartan.Methods GMC were cultured in vitro and the groups were designed as follows: low glucose group（NG, 5.5 mmol/L d-glucose）, high glucose group（HG, 30 mmol/L d-glucose）, valsartan group（HG+val, 30 mmol/L d-glucose+valsartan 10 μmol/L） and mannitol group（MG, 24.5 mmol/L mannitol +5.5 mmol/L d-glucose）. The expression of phosphate (p-) ERK1/2 protein was detected by immunocytochemical technique and Western blot. RT-PCR and radioimmunoassay were respectively used to measure the expression of TGF-β1 mRNA in mesangial cells and the content of type Ⅳ collagen in supernatant. Results The strongly positive staining of p-ERK1/2 in mesangial cells exposed to high glucose was observed not only in cytoplasm, but also in nuclei at 12 h, with an increasing tendency to 72 h (P < 0.01). The level of TGF-β1 mRNA in mesangial cells and the content of type Ⅳ collagen in the supernatant of HG group were also significantly higher than those of NG group (P < 0.01). Compared with those in HG group, the above parameters were significantly down-regulated in HG+val group (P < 0.01), whereas there were no significant differences of above parameters between MG group and NG group. Conclusion The expression of p-ERK1/2 is up-regulated in GMC exposed to high glucose medium, which can be inhibited by valsartan.