目的 支链氨基酸（branched-chain amino acids, BCAAs）相关的代谢特征与胰岛素抵抗密切相关,并可预测糖尿病的发生和干预效果。为了更深入地了解BCAA在胰岛素抵抗中的作用及相关机制,通过限制饲料中BCAA水平,观察其限制对高脂诱导的胰岛素抵抗C57BL/6J小鼠胰岛素敏感性及胰岛功能的影响。方法 雄性3月龄C57BL/6J小鼠按体重随机分为对照组、高脂组和高脂限制支链氨基酸组,分别给予普通饲料、高脂饲料和高脂饲料的基础上减少50%BCAA,干预24 w后,葡萄糖耐量试验评价胰岛素抵抗模型是否建立成功。实验结束后,动物禁食,处死后收集各组小鼠血清和胰腺组织。液相色谱与串联质谱联用检测血清BCAA水平,ELISA法测定血清胰岛素水平,比色法检测血清葡萄糖水平,计算胰岛素抵抗指数。苏木素-伊红染色（HE）观察各组小鼠胰腺组织病理形态,免疫荧光染色检测胰岛素含量,TUNEL染色观察胰岛细胞凋亡。结果 高脂喂养24 w,高脂组体重、空腹血糖、血胰岛素、胰岛素抵抗指数、葡萄糖耐量试验血糖曲线下面积和三种BCAA水平均显著高于对照组。与高脂组相比,BCAA限制组三种BCAA水平显著下降,体重显著降低,空腹血糖、血胰岛素、葡萄糖耐量试验血糖曲线下面积无显著差异。与对照组相比,高脂组部分胰岛形态不规则,出现空泡样变性,胰岛素分泌增加。与高脂组相比,BCAA限制组胰岛形态相对规则,胰岛面积缩小,胰岛数目减少,胰岛素分泌减少,胰岛细胞凋亡减少。结论 在高脂膳食背景下长期BCAA限制对总体胰岛素敏感性无明显改善,但是对胰岛β细胞具有保护作用。
Abstract
Objective To better understand the role and related mechanisms of BCAA in insulin resistance, we studied the effects of BCAA restriction on insulin sensitivity and islet function in high-fat diet (HFD) induced insulin resistance mouse model. Methods Male 3 months old C57BL/6J mice were randomly divided into three groups, and fed normal diet, high-fat diet and high-fat diet with 50% of BCAA restriction for 24 weeks. At the end of the experiment, the glucose tolerance test (GTT) was performed. After overnight fast, mice were killed and serum and pancreas were collected. Serum levels of BCAA, glucose and insulin were tested and HOMA-IR was calculated. The pathological changes of pancreas were observed by hematoxylin-eosin staining (HE). Insulin content in islet was detected by immunofluorescence, and the apoptosis of islet was observed by TUNEL staining. Results After 24 weeks feeding, the body weight, fasting serum levels of glucose, insulin and BCAA, insulin resistance index, and area under curve (AUC) of GTT were significantly higher than those in the control group. Compared with the HFD group, the serum BCAA level and body weight were significantly decreased in the BCAA restriction group, but there was no significant difference in fasting glucose, insulin or AUC of GTT between the two groups. Compared with the control group, some islets in the HFD group showed irregular morphology and vacuolar degeneration, and the insulin content in the islet were increased. The BCAA restriction group had relatively regular islet morphology, and the area of pancreatic islets, the number of islet, insulin content of islet and apoptosis of islet cells were decreased compared with the HFD group. Conclusion Long-term BCAA restriction combined with HFD did not have significant effects on the overall insulin sensitivity, but it exerted protective actions on pancreatic islet β cells.
关键词
支链氨基酸 /
胰岛素敏感性 /
高脂膳食 /
肥胖
Key words
branched-chain amino acids /
insulin sensitivity /
high-fat diet /
obesity
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基金
国家自然科学基金青年基金项目（No.82003463）
