Hou Zhi-qiang, Li Hong-liang, Zhao Jia-jun, Li Guang-wei
Endocrinology and Metabolism Centre, China-Japan Friendship Hospital, Ministry of Public Health, Beijing 100029, China.
Zhonghua Yi Xue Za Zhi. 2008 Jul 22;88(28):2002-4.
To investigate the effect of intermittent high glucose (IHG) on the pancreatic islet beta-cell function and mechanism thereof.
Rat pancreatic islet p-cells of the line INS-1 were cultured and randomly divided into 3 groups: IHG group exposed to fluctuating concentrations of glucose, stable high glucose (SHG) group exposed to 16. 7 mmol/L glucose, and control group exposed to normal concentration (5.5 mmol/L) glucose. 24, 48, and 72 hours later radioimmunoassay was used to detect the insulin secretion index (ISI). 72 h later, the concentration of insulin in the cells was detected with radioimmunoassay. The contents of oxidative stress markers, nitrotyrosine (NT) and 8-hydroxy-2-deoxyguanosine (8-OHdG) were detected. Real-time PCR was used to detect the mRNA expression of peroxiredoxin 1 (PDX-1), ATF-4, one of the transcription factors of the family bZIP, and insulin. Western blotting was used to detect the protein expression of ATF-4.
The ISI of the IHG and SHG groups decreased time-dependently, The ISI of IHG and SHG groups were 0.64 +/- 0.11 and 1.31 +/- 0. 04 respectively, both significantly lower than that of the control group (1.67 +/- 0.23, both P < 0.05). The intracellular insulin contents of the IHG and SHG groups were (10.91 +/- 0.14) and (11.08 +/- 0.03) +/- U/microg respectively, both significantly lower than that of the control group [(12.37 +/- 0.37) microU/microg, both P < 0.05]. The intracellular concentrations of 8-OHdG and NT of the SHG and IHG groups, were significantly higher than those of the control group (all P < 0.01), and those of the IHG group were significantly higher than those of the SHG group (both P < 0.05). The mRNA and protein expression levels of ATF-4 of the IHG group were all significantly higher than those of the control group (all P < 0.05) and those of the IHG group were significantly higher than those of the SHG group (both P < 0.05).
IHG and SHG induce severe impairment in pancreatic islet beta cell functions, especially IHG, which is closely associated with the aggravation of oxidative stress and endoplasmic reticulum stress triggered by intermittent high glucose.
探讨间歇性高糖（IHG）对胰岛β细胞功能的影响及其机制。
培养大鼠胰岛β细胞系INS-1，随机分为3组：IHG组，暴露于波动浓度的葡萄糖；稳定高糖（SHG）组，暴露于16.7 mmol/L葡萄糖；对照组，暴露于正常浓度（5.5 mmol/L）葡萄糖。24、48和72小时后，采用放射免疫分析法检测胰岛素分泌指数（ISI）。72小时后，用放射免疫分析法检测细胞内胰岛素浓度。检测氧化应激标志物硝基酪氨酸（NT）和8-羟基-2-脱氧鸟苷（8-OHdG）的含量。采用实时定量PCR检测过氧化物酶1（PDX-1）、碱性亮氨酸拉链家族转录因子之一的ATF-4及胰岛素的mRNA表达。采用蛋白质免疫印迹法检测ATF-4的蛋白表达。
IHG组和SHG组的ISI均呈时间依赖性下降，IHG组和SHG组的ISI分别为0.64±0.11和1.31±0.04，均显著低于对照组（1.67±0.23，均P<0.05）。IHG组和SHG组细胞内胰岛素含量分别为（10.91±0.14）和（11.08±0.03）μU/μg，均显著低于对照组[（12.37±0.37）μU/μg，均P<0.05]。SHG组和IHG组细胞内8-OHdG和NT浓度均显著高于对照组（均P<0.01），且IHG组高于SHG组（均P<0.05）。IHG组ATF-4的mRNA和蛋白表达水平均显著高于对照组（均P<0.05），且IHG组高于SHG组（均P<0.05）。
IHG和SHG均可导致胰岛β细胞功能严重受损，尤其是IHG，这与间歇性高糖引发的氧化应激和内质网应激加剧密切相关。
