2型糖尿病大鼠模型制备的影响因素及其特点

Influencing Factors in the Development of Rat Model of Type 2 Diabetes Mellitus and Their Characteristics

目的探讨高脂喂养联合低剂量链脲佐菌素(Streptozotocin,STZ)制备2型糖尿病大鼠模型的造模方法和影响因素。方法4周龄雄性Sprague Dawley(SD)大鼠45只随机分为三组:(1)正常组(normal control,NC),9只,普通饲料喂养。(2)高脂组(high fat,HF),9只,高脂饲料喂养。(3)糖尿病模型组,根据高脂喂养时间差异和STZ剂量不同设计了3种模型制备方法:A组,9只,高脂喂养满4周,注射STZ 30 mg/kg;B组,9只,高脂喂养满8周,注射STZ 20 mg/kg;C组,9只,高脂喂养满8周,注射STZ 30 mg/kg。所有大鼠于48h、2周和4周后行灌胃葡萄糖耐量试验(OGTT)评价成模率和血糖波动情况。实验结束时测定血清胰岛素、甘油三酯(TG)和胆固醇(TC),RT-PCR测定胰腺内胰岛素mRNA表达水平,免疫组化染色观察胰岛细胞形态学特点,用彩色图像分析系统进行定量比较。结果糖尿病C组血糖显著升高,成模后2周血糖下降,4周后又上升到基线水平,成模率100%。糖尿病A组、B组在4周后血糖逐渐降低到接近正常水平,成模率分别为55.6%、11.1%。C组与HF组相比,胰岛素敏感性显著下降(P<0.01)。β细胞内胰岛素水平下降39.3%(P<0.01),胰岛内β细胞所占比例下降了79.2%(P<0.01),胰腺内胰岛素mRNA表达水平减少19.2%(P<0.01),α细胞升高了1倍(P<0.01)。结论高脂喂养8周后腹腔注射低剂量STZ(30 mg/kg)制备的2型糖尿病大鼠模型,成模率高,模型稳定。

Objective To evaluate the influencing factors and explore a better method of developing rat model of type 2 diabetes by high fat chow and low dose of streptozotoein （STZ） injection. Methods Forty-five male Sprague Dawley （SD） rats, aged 4 week-old, were randomly divided into three groups： （1） Normal control group （NC, n = 9）, fed with a standard chow, （2） high-fat group （HF, n = 9）, fed with high-fat chow, （3） diabetes mellitus group, induced by intraperitoneal injection （ip） of STZ after high-fat chow feeding. The diabetic group was further divided into 3 subgroups： The group A （n = 9） was induced by 4 weeks of high-fat chow feeding followed by 30 mg/kg of STZ injection. Group B （n = 9） was induced by 8 weeks of highfat feeding followed by 20 mg/kg of STZ. Group C （n = 9） was induced by 8 weeks of high-fat feeding followed by 30 mg/kg of srrz. OGTT was performed for 3 times at 48 hours, 2 weeks and 4 weeks after STZ injection. Fasting serum insulin level, total serum cholesterol （TC） and triglyceride （TG） were measured. Insulin mRNA was detected by RT-PCR. Morphologic changes of islet cells stained by immunohistochemistry were analyzed and quantified with a color image analyzer. Results In group C, the fasting blood glucose level increased prominently and its variation appeared as decreasing in the first week and then increasing closely to baseline level within 4 weeks. The morbidity of diabetes was 100% . However, the diabetic morbidity in group A and group B was only 55.6% （5/9） and 11.1% （1/9）, respectively. Compared with HF group, insulin sensitivity was women markedly （ P 〈 0.01 ）, and the reduction of insulin content in [3 cells by 39.3 % （ P 〈 0.01 ）, β cell mass by 79.2 % （ P 〈 0.01 ） and insulin mRNA expression in the pancreas by 19.2% （ P 〈 0.01 ） were detected in group C. On the contrary, the a cells mass increased by almost 1-fold （ P 〈 0.01 ）. Conclusion Rat model of type 2 diabetes induced by 4 weeks of high-fat chow feeding and low dose STZ （30 mg/kg） iniection presents high morbidity of diabetes and stable features.