糖尿病大鼠肾小动脉内膜中膜厚度比与骨基质蛋白的相关性

目的 观察糖尿病大鼠肾小动脉骨基质蛋白表达情况及内膜中膜厚度比变化，探讨其相关关系及对糖尿病肾病血管病变的影响。 方法 70只健康雄性SD大鼠被随机分为糖尿病肾病组（DN，n = 40）和健康对照组(N，n = 30)。DN大鼠模型采用链脲佐菌素（STZ）腹腔注射诱导，成功35只。N组予同等剂量柠檬酸缓冲液。分别于4、12、24周处死动物，应用免疫组化方法检测各时间点肾小动脉中骨基质蛋白核心结合因子（Cbfα1）、骨形态蛋白2（BMP-2）的表达。原位杂交法检测其基因表达。应用免疫荧光方法检测肾小动脉内膜中膜厚度比。实时荧光定量PCR法测定BMP-2及基质Gla蛋白（MGP）的基因表达。 结果 DN组各时间点血糖及尿蛋白量(24 h)均较N组显著增高（P < 0.05），自第12周开始，DN组血肌酐、血磷较N组显著增高（P < 0.05）。免疫组化显示DN组肾小动脉4周时已有Cbfα1、BMP-2表达，随时间延长表达逐渐增强，24周表达最强，各时间点均显著高于N组（P < 0.05）。原位杂交显示Cbfα1、BMP-2仅在肾小动脉中有表达，表达趋势同免疫组化结果；4周时主要表达于血管内弹力层；12周后外弹力层及肌层表达也增强。实时荧光定量PCR显示DN组4周时BMP-2 mRNA已有表达，随时间延长表达逐渐升高，24周最高（P < 0.05）； DN组MGP表达量 4周最高，随时间延长表达逐渐降低，24周最低（P < 0.05）。而N组BMP-2和MGP mRNA各时间点表达量差异均无统计学意义。免疫荧光显示第4、12周时，DN组内膜中膜厚度比与N组差异均无统计学意义；24周时显著高于N组（P < 0.05）。DN组Cbfα1与BMP-2呈正相关（r = 0.670, P < 0.01）；与MGP呈负相关（r = －0.466，P < 0.05）；小动脉内膜中膜厚度比与Cbfα1、BMP-2呈正相关（r = 0.727，P < 0.01； r = 0.581，P < 0.01）。 结论 DN早期小动脉内膜中膜厚度比与Cbfα1、BMP-2呈正相关。Cbfα1、BMP-2、MGP可能参与了DN血管病变。

Correlation between the ratio of intima to tunica media thickness and the expression of bone matrix proteins in small renal artery of diabetic nephropathy rats

Objective To observe the expression of bone matrix proteins and the change of intima-tunica media thickness ratio in diabetic rat small renal artery and to explore their correlation and effects on diabetic nephropathy. Methods Seventy healthy SD rats were randomly divided into diabetic group(DN,n=40)and normal control group(N,n=30).DN rat model was induced by streptozotocin(STZ)intraperitoneal injection and the N group rats were given the same dose of citrate buffer.Thirty-five rats were successfully induced in DN group.The rats were sacrificed at week 4,12 and 24,respectively.The protein and mRNA expression of core-bind factor alpha 1(Cbfcd).bone morphogenetic protein 2(BMP-2)and matrix Gla protein(MGP)in smallrenal artery were detected by immunohistochemistry,in-situ hybridization and real-time PCR at each time point. Results Cbfctl and BMP-2 were expressed obviously in small renal artery of DN group by immunohistochemistry stain and in-situ hybridization from 4 to 24 weeks compared with N group at each time point,reaching the peak at week 24.Real-time PCR showed that the MGP mRNA was evidently increased at week 4,slightly decreased at week 12,lowest at week 24in DN group.The BMP-2 mRNA began to increase from week 4 onward,being peak at week 24in DN group.The ratio of intima to tunica media thickness had no significant difference in DN group compared with N group at week 4,but at week 12 and 24 there were significant difference between them.There was a positive correlation between Cbfα1 and BMP-2 expression,but they were negatively correlated with the expression of MGP.The ratio of intima to tunica media thickness was significantly-correlated with the expression of Cbfα1 and BMP-2. Conclusions The ratio of intima to tunica media thickness is positively correlated with Cbfα1 and BMP-2 in small renal artery of early DN.Cbfα1,BMP-2 and MGP may be involved in the progression of vascular lesions in DN.