应用高葡萄糖钳夹技术评估高糖喂养小鼠胰岛细胞功能

Evaluating pancreatic β cell function in sucrose-fed mice by hyperglycemic clamp technique

目的利用高葡萄糖钳夹技术探讨高糖喂养小鼠胰岛B细胞功能。方法将16只4周龄C57BL／6J品系小鼠随机数字表法分为2组（各8只），分别用高糖与普通饲料喂养，8周后行腹腔葡萄糖耐量实验比较2组小鼠葡萄糖耐量，行胰岛素耐量实验比较2组小鼠外周组织对胰岛素的敏感性，应用高葡萄糖钳夹技术比较模型小鼠在体胰岛β细胞第1时相和第2时相胰岛素分泌改变。钳夹实验结束3～4d后麻醉动物，取小鼠肝脏，利用庚烷-异丙醇-吐温的方法提取肝脏内甘油三酯及总胆固醇。组间数据比较采用t检验。结果喂养10周时，高糖组小鼠体质量[（18．0±0．8）g]低于普食组[（23．6±0．5）g]，2组差异有统计学意义（扭5．595，P〈0．05）。高糖组糖耐量曲线下面积为（103±3）mmol／L，显著高于普食组的（91±3）mmol／L（t=2．487，P〈0．05）。普食组葡萄糖利用指数（KITT）与高糖组差异无统计学意义（分别为0．53±0．08和0．54±0．14，t=2．360，P〉0．05）。高葡萄糖钳夹显示，高糖组第1时相胰岛素水平较普食组下降了49．6％[分别为（0．71±0．26）和（I．41±0．44）μg/L；t=2．943，P〈0．05]；高糖组平均葡萄糖输注率为（6．8±2．2）mg·kg-1·min-1，也较普食组的（20．2±2．3）mg·kg-1·min-1降低了66．3％（t=4．206，P〈0．05）。结论高糖喂养早期（8周），小鼠发生葡萄糖耐量降低，主要为胰岛β细胞第1时相胰岛素分泌减弱所致，并非外周胰岛素敏感性改变引起。

Objective To evaluate the pancreatic β cell function in sucrose-fed mice by hyperglycemic clamp technique. Methods Sixteen C57BL/6J mice were randomly divided into two groups and fed with either high sucrose diet （ n = 8 ） or chow food （ n = 8 ） for 8 weeks. Intraperitoneal glucose tolerance test （IPGTY） was carried out to detect glucose tolerance, intraperitoneal insulin tolerance test was applied to detect peripheral insulin sensitivity, hyperglycemic clamp technique was used to detect the first and second phase of insulin secretion in the two groups. Liver lipids were extracted with heptane-isopropanol- tween methods in the mice. The data was compared between the two groups by using t test. Results In contrast to chow-fed mice, the body weight of sucrose-fed mice decreased by 23.4 % （ （23.6 ± 0. 5 ） g and （ 18.0 ±0. 8） g, respectively; t = 5. 595, P 〈 0. 001 ）. The area under the IPGTT curve from sucrose-fed mice was much higher than that from chow-fed mice （（ 103± 3） mmol/L and （91 ± 3） mmoL/L, respectively; t = 2. 487, P 〈 0. 05 ）. No difference could be observed in glucose disappearance rate （KITT） between the two groups（0.53 ± 0.08 and 0.54 ±0.14, respectively;t = 2. 360, P 〉 0.05）. During hyperglycemic clamp, the first phase of insulin secretion decreased by 49. 6% in sucrose-fed mice compared with that in chow-fed mice （ （0. 71 ±0. 26） μg/L and （ 1.41±0. 44） μg/L, respectively; t =2. 943, P 〈 0. 05）. The average glucose infusion rate （GIR） was （20. 2 ±2. 3） mg / kg-1 min-1 in chow-fed mice and which was decreased by 66. 3 % in sucrose-fed mice （ （ 6. 8 ± 2. 2 ） mg kg- 1 min- 1 ） （ t = 4. 206,P 〈 O. 05） from the sucrose-fed mice. Conclusions Eight-week feeding with a high sucrose diet in mice induced glucose intolerance. It might be due to reduction in the first phase insulin secretion from pancreatic β cells, but not to peripheral insulin resistance.