银杏叶提取物、卡托普利和缬沙坦抑制糖尿病肾病大鼠肾纤维化的机制及其比较

Inhibitory mechanism of Ginkgo biloba extract,Captopril,and Vaisartan on kidney fibrosis of diabetic nephropathy rats and their comparison

目的研究银杏叶提取物(GBE)、卡托普利和缬沙坦对糖尿病肾病(DN)大鼠肾纤维化的防治作用及其机制.并比较它们对DN作用的异同。从而为联合用药提供理论基础。方法SD大鼠一次性ip链脲佐菌素(STZ) 60 mg/kg诱导DN肾病模型。造模成功的DN大鼠随机分为4组:DN组、GBE治疗组(100 mg/kg)、卡托普利治疗组(10 mg/kg)和缬沙坦治疗组(15 mg/kg)。对照组及DN组ig给予1%羧甲基纤维素治疗。治疗12周后收集标本。电镜观察肾小球基底膜(GBM)厚度;放射免疫法测定肾皮质层黏蛋白和Ⅳ型胶原的量;免疫组化法测定基质金属蛋白酶2(MMP2)、结缔组织金属蛋白酶抑制剂2(TIMP2)和结缔组织生长因子(CTGF)蛋白表达;RT-PCR法测定肾皮质转化生长因子β_1(TGF-β_1)mRNA的表达。结果GBE、卡托普利和缬沙坦均能显著改善DN大鼠GBM增厚现象,降低肾皮质中层黏蛋白和Ⅳ型胶原的量。3种药物一方面通过抑制直接促进细胞外基质(ECM)合成的TGF-β_2和CTGF的表达而抑制ECM的积聚,另一方面通过其分解平衡系统MMP2/TIMP2而使ECM表达减少。并且发现GBE改善GBM的作用较卡托普利和缬沙坦弱,而抑制肾皮质层黏蛋白和Ⅳ型胶原的作用较强。结论GBE、卡托普利和缬沙坦均可抑制ECM的大量表达,并且GBE抑制GBM增厚的作用较其他两药弱,而抑制肾皮质ECM的表达较其他两药强,这对于临床联合用药具有非常重要的意义。

Objective To observe the preventive and therapeutic effects and the mechanisms of Ginkgo biloba extract （GBE）, Captopril, and Valsartan on the early stage of diabetic nephropathy （DN） rats, and to compare the differences among them so as to establish the combination of medication. Methods Diabetes mellitus models of SD rats were induced by ip STZ and the developed DN rats were divided randomly into four groups： DN rats with 1% carboxymethyl cellulose （CMC） solution treated （DN group）; DN rats with 100 mg/kg of GBE treated （GBE group）, DN rats with 10 mg/kg of Captopril treated （CAP group）, and DN rats with 15 mg/kg of Valsartan （VAL group）. Rats of normal group （NS group） and DN group were treated with 1% CMC solution. After 12-week treatment, samples were collected. The uhrastructural morphology and thickness of glomcrular base membrane （GBM） were observed under transmission electron microscope ; Collagen Ⅳ and laminin in kidney cortex were detected by redioimmunity ; MMP2 and TIMP2 proteins and CTGF were measured by immunohistochemistry; the expression of TGF-β1 mRNA in kidney cortex were determined by a reverse transcription polymerase chain reaction （RT-PCR）. Results GBE, Captopril, and Valsartan could markedly reduce the thickness of GBM, decrease the contents of laminin and collagen Ⅳ of DN rats significantly. They could inhibit the expression of TGF-β1 and CTGF which induced extracellular matrix （ECM） directly; On the other hand, they could ameliorate the disequilibrium of MMP2 and TIMP2. Furthermore, The effects of GBE on reducing the thickness of GBM were weaker than that of Captopril and Valsartan, and on suppressing the ECM of kidney cortex were stronger than that of the two drugs. Conclusion GBE, Captopril, and Valsartan could all inhibit the accumulation of ECM. Moreover, GBE has the weaker effects on decreasing the thickness of GBM than Captopril and Valsartan, and has the stronger effects on suppressing the ECM of kidney cortex than the two drugs, which means vitally to postpone kidney fibrosis of DN rats on the combination of medication.