低剂量他克莫司导致大鼠糖耐量异常机制的初步探讨

A preliminary study on the mechanism of the abnormal glucose intolerance induced by low doses of tacrolimus in rats

目的初步探讨不同剂量他克莫司导致大鼠血糖升高的机制。方法将20只SD大鼠随机分为低剂量组(0.1 mg/kg)、中剂量组(0.5 mg/kg)、高剂量组(1.0 mg/kg)、对照组4组,每组5只;前3组每日皮下注射相应剂量的他克莫司,连续注射1周,对照组给予等体积橄榄油。实验期间隔日监测动物体质量。药物干预1周后行腹腔注射葡萄糖耐量试验(2 g/kg),统计空腹血糖(FBG)、空腹胰岛素(FINS)和稳态模型下胰岛素抵抗指数(HOMA-IR)。摘取大鼠胰体尾部制备病理组织切片,免疫组化染色测量胰岛β细胞面积,qPCR检测胰岛组织胰岛素分泌相关基因Epac、Rim2、Piccolo、Rab3a、Munck13的表达。结果与对照组相比,他克莫司干预组体质量降低,中高剂量组的下降幅度大于低剂量组。不同剂量他克莫司干预组均出现糖耐量异常,中、高剂量组血糖水平和曲线下面积均较低剂量组升高,且呈剂量依赖性(P<0.05)。实验期间4组间FBG、FINS和HOMA-IR比较差异无统计学意义(P>0.05)。免疫组化染色结果显示中高剂量组β细胞数量较低剂量组与对照组减少(P<0.05),低剂量组与对照组差异无统计学意义(P>0.05)。低剂量组胰岛素分泌相关蛋白Epac、Rim2、Piccolo、Rab3a、Munck13转录水平均较对照组下降(P<0.05)。结论在胰岛β细胞数量并未减少,且未出现胰岛素抵抗的情况下,小剂量他克莫司干预所引起的糖耐量异常与胰岛素分泌过程紊乱相关。

Objective To investigate potential mechanism of different doses of tacrolimus leading to the elevated blood glucose in rats.Methods Twenty SD rats were randomly divided into low dose group(0.1 mg/kg),middle dose group(0.5 mg/kg),high dose group(1.0 mg/kg)and control group(n=5 for each group).The first three groups were injected subcutaneously with tacrolimus for one week,and the control group was given equal volume olive oil.Body weights of the rats were monitored every other day.After 1 week of drug intervention,intraperitoneal glucose tolerance test(2 g/kg)was performed.The fasting blood glucose(FBG),fasting insulin(FINS)and insulin resistance index(HOMA-IR)under steady state model were counted.Pathological tissue sections prepared from the tail of rat pancreas.The area of isletβcells was measured by immunohistochemical staining,and the expressions of insulin-secreting genes Epac,Rim2,Piccolo,Rab3a and Munck13 in islet tissue were detected by real-time quantitative PCR.Results Compared with the control group,the body mass decreased in tacrolimus intervention group,and the decreased weights were larger in middle and high dose groups than that of low dose group.Abnormal glucose tolerance was found in tacrolimus intervention group,and blood glucose level and area under curve were higher in middle and high dose groups than those in low dose group with a dose-dependent manner(P<0.05).There were no significant differences in FBG,FINS and HOMA-IR between the four groups(P>0.05).The results of immunohistochemistry showed that the number of β cells was not significantly decreased in the middle and high dose group than that of control group(P<0.05),but there was no significant difference between the low dose group and the control group(P>0.05).The transcription levels of secretory related proteins Epac,Rim2,Piccolo,Rab3a and Munck13 were decreased in low dose group compared with those of the control group(P<0.05).Conclusion The abnormal glucose tolerance caused by low dose short-term intervention is related to the disorder of insulin secretion when the number of islet β cells does not decrease and there is no insulin resistance.