Liu Shuai-Nan, Liu Quan, Sun Su-Juan, Hou Shao-Cong, Wang Yue, Shen Zhu-Fang
Yao Xue Xue Bao. 2014 Nov;49(11):1554-62.
This study is to evaluate the effects of the metformin (Met) on β cell function of diabetic KKAy mice. Female diabetic KKAy mice selected by insulin tolerance test (ITT) were divided randomly into two groups. Con group was orally administered by gavage with water, Met group with metformin hydrochloride at a dose of 0.2 g x kg(-1) for about 12 weeks. ITT and glucose tolerance tests (OGTT) were determined. Beta cell function was assessed by hyperglycemic clamp. Pancreatic biochemical indicators were tested. The changes of gene and protein expression in the pancreas and islets were also analyzed by Real-Time-PCR and immunostaining. Met significantly improved glucose intolerance and insulin resistance in KKAy mice. Fasting plasma glucose and insulin levels were also decreased. In addition, Met markedly increased glucose infusion rate (GIR) and elevated the Ist phase and maximum insulin secretion during clamp. It showed that Met decreased TG content and iNOS activities and increased Ca(2+) -Mg(2+)-ATPase activity in pancreas. Islets periphery was improved, and down-regulation of glucagon and up-regulated insulin protein expressions were found after Met treatment. Pancreatic mRNA expressions of inflammation factors including TLR4, NF-κB, JNK, IL-6 and TNF-α were down-regulated, p-NF-κB p65 protein levels also down-regulated by Met. And mRNA expressions of ion homeostasis involved in insulin secretion including SERCA2 and Kir6.2 were up-regulated by Met. Met increased SIRT5 expression level in pancreas of KKAy mice under the hyperglycemic clamp. These results indicated that chronic administration of Met regulated pancreatic inflammation generation, ion and hormone homeostasis and improved β cell function of diabetic KKAy mice.
本研究旨在评估二甲双胍（Met）对糖尿病KKAy小鼠β细胞功能的影响。通过胰岛素耐量试验（ITT）筛选出的雌性糖尿病KKAy小鼠被随机分为两组。对照组经口灌胃给予水，Met组给予盐酸二甲双胍，剂量为0.2 g·kg⁻¹，持续约12周。测定ITT和葡萄糖耐量试验（OGTT）。通过高血糖钳夹评估β细胞功能。检测胰腺生化指标。还通过实时定量聚合酶链反应（Real-Time-PCR）和免疫染色分析胰腺和胰岛中基因和蛋白质表达的变化。Met显著改善了KKAy小鼠的葡萄糖不耐受和胰岛素抵抗。空腹血糖和胰岛素水平也降低。此外，Met显著提高了葡萄糖输注速率（GIR），并在钳夹期间提高了第一相和最大胰岛素分泌。结果表明，Met降低了胰腺中甘油三酯（TG）含量和诱导型一氧化氮合酶（iNOS）活性，并增加了钙镁ATP酶（Ca²⁺-Mg²⁺-ATPase）活性。胰岛外周得到改善，Met治疗后发现胰高血糖素下调，胰岛素蛋白表达上调。Met下调了包括Toll样受体4（TLR4）、核因子κB（NF-κB）、应激活化蛋白激酶（JNK）、白细胞介素-６（IL-6）和肿瘤坏死因子-α（TNF-α）在内的炎症因子的胰腺mRNA表达，Met还下调了p-NF-κB p65蛋白水平。Met上调了参与胰岛素分泌的离子稳态相关基因，如肌浆网Ca²⁺-ATP酶2（SERCA2）和内向整流钾离子通道蛋白6.2（Kir6.2）的mRNA表达。在高血糖钳夹条件下，Met提高了KKAy小鼠胰腺中沉默信息调节因子5（SIRT5）的表达水平。这些结果表明，长期给予Met可调节胰腺炎症的产生、离子和激素稳态，并改善糖尿病KKAy小鼠的β细胞功能。
