MR mDxion-Quant技术评价早期糖尿病肾病大鼠肾脏脂质沉积的实验研究

Evaluation of renal lipid deposition in rats with early diabetic nephropathy using MR mDxion-Quant technique

目的 探讨MR mDxion-Quant技术评价早期糖尿病肾病(DN)大鼠肾脏脂质沉积的价值。方法 选取6周龄健康清洁级(SPF级)雄性SD大鼠70只,分为实验组(50只)和对照组(20只)。实验组用高脂饮食配合链脲佐菌素建立2型糖尿病模型。于成模后第4、8、12、16周末分批行肾脏MR扫描得到肾脏脂肪分数(FF)。随后行血脂及肾脏病理检查。计算肾脏细胞内脂滴累计光密度值/细胞总面积值(IOD/TAC)。根据病理结果将实验组中病理分级为Ⅰ、Ⅱ级的大鼠纳入早期DN组(n=15),将对照组中肾脏未见异常的大鼠纳入正常对照组(n=13)。共28只大鼠纳入研究。比较早期DN组与正常对照组之间各指标的差异,分析肾脏FF值与其余指标的相关性。结果 早期DN组大鼠肾脏FF值、细胞内脂滴IOD/TAC、TC、TG、LDL较正常对照组升高,HDL含量降低(均P<0.001),FF值与IOD/TAC、TC、TG、LDL及糖尿病病程呈正相关(r分别为0.85、0.66、0.71、0.76、0.85,均P<0.01),与HDL呈负相关(r=-0.71,P<0.01)。结论 mDxion-Quant技术可无创性定量评估早期DN大鼠肾脏脂质沉积。早期DN大鼠肾脏脂肪含量较正常对照组增加,且与糖尿病病程、血脂水平相关。

Objective To evaluate the value of MR mDxion-Quant technique in the diagnosis of renal lipid deposition in early diabetic nephropathy(DN)in a rat model.Methods Seventy male SD rats were randomly divided into experimental group(n=50)and control group(n=20).A high-fat diet combined with low-dose streptozotocin were performed to the rats in experimental group to establish a T2DM model.MR mDxion-Quant scans were performed to obtain renal fat fraction(FF)on the rats in batches at the end of the 4th,8th,12th,and 16th week after T2DM model was built.Blood lipid level and renal pathological examination were performed after MR scan.The ratio of integrated optical density of the intracellular lipid droplets and total area of all the cells(IOD/TAC)was calculated.Based on the results of the renal histopathology,the rats with DN with class I and II in experimental group were defined as early-stage DN group,and the rats with no renal abnormalities in control group were defined as normal control group.The differences of the above-mentioned indexes between the normal control group and early-stage DN group were compared,and the correlations between renal FF value and other indexes in early DN group were analyzed.Results A total of 28 rats(15 early-stage DN and 13 control)were eligible for this study.In early DN group,renal FF value,IOD/TAC,serum total cholesterol(TC),triglyceride(TG)and low-density lipoprotein(LDL)levels were higher than those in the control group,while high-density lipoprotein(HDL)level decreased(all P<0.001).Positive correlations were found between FF and each of the following:TC,TG,LDL and the progression of T2DM(r=0.85,0.66,0.71,0.76 and 0.85,respectively,all P<0.01),while negative correlation were found between FF and HDL(r=-0.71,P<0.01).Conclusion MR mDixon-Quant technique could evaluate the renal lipid deposition accurately and noninvasively.Renal FF value in subjects with early DN is higher than those without diabetes,and it is associated with the progression of T2DM and the blood lipid levels.