利拉鲁肽对高脂喂养大鼠胰腺β细胞ATF4/CHOP通路的影响

Effects of liraglutide on ATF4/CHOP pathway of pancreatic beta cells in rats fed with high-fat diet

目的观察利拉鲁肽对高脂喂养大鼠胰腺GRP78、转录活化因子4(ATF4)、CCAAT区/增强子结合蛋白同源蛋白(CHOP)、TRB3蛋白和mRNA表达情况,探讨利拉鲁肽对高脂喂养大鼠胰腺ATF4/CHOP通路的影响。方法将雄性Wistar大鼠44只分为对照组、高脂组、干预组1、干预组2,每组11只,对照组给予普通饮食,其余3组给予高脂饮食喂养8周后,干预组1给予利拉鲁肽100μg·kg-1·d-1皮下注射;干预组2给予利拉鲁肽200μg·kg-1·d-1皮下注射。药物干预2周后处死,每组取5只大鼠行清醒状态下高胰岛素-正葡萄糖钳夹试验计算葡萄糖输注率(GIR),测定其余大鼠空腹血糖(FBG)、空腹胰岛素(FINS)、血清游离脂肪酸(FFA)、总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)和高密度脂蛋白胆固醇(HDLC),计算胰岛β细胞功能指数(HOMA-β),Western blot和Realtime-PCR技术检测胰腺GRP78、ATF4、CHOP和TRB3蛋白及mRNA的表达。结果与对照组相比,高脂组FBG、FFA、TC、FINS、TG、LDL-C水平显著升高,HDL-C、GIR和HOMA-β明显下降(P<0.05或P<0.01),与高脂组相比,干预组2HDL-C、GIR和HOMA-β升高(P<0.05或P<0.01),其余指标明显下降;与干预组1相比,干预组2的血FGB、FFA、TC下降,GIR和HOMA-β升高(P<0.05)。与对照组相比,高脂组GRP78、ATF4、CHOP和TRB3蛋白及mRNA的表达明显升高;与高脂组相比,干预组1与干预组2随利拉鲁肽浓度升高,GRP78、ATF4、CHOP和TRB3蛋白及mRNA表达逐渐下降。结论利拉鲁肽可呈浓度依赖性改善高脂喂养大鼠胰岛素抵抗及保护胰岛β细胞,其作用机制可能涉及胰腺内质网ATF4/CHOP通路。

Objective To observe the effects of liraglutide on GRP78, ATF4, CHOP and TRB3 protein and mRNA expression in rats which fed with high fat diet,and to explore the effect of liraglutide on ATF4/CHOP pathway of pancreas in rats fed with high fat diets. Methods Forty-four male Wistar rats were randomly divided into the control group, high fat group,intervention group 1 and intervention group 2,11 cases in each group. The control group was fed with common food, other 3 groups were fed with high fat diet for 8 weeks. Then the intervention group 1 was given with liraglutide （100 μg· kg-1 · d-1 ） by subcutaneous in- jectionl the intervention group 2 was given liragtutide （200 μg· kg-1· d-1 ） by subcutaneous injection. After 2 weeks medication intervention, the rats were killed. Five rats were taken from each group and performed the hyperinsulinemic englycemic clamp ex- periment under waking state for calculating the glucose infusion rate （GIR）.. The fasting blood glucose （FBG）, fasting insulin （FINS）, serum free fattyacid（FFA）, total cholesterol（TC）, triglyceride（TG）,low density lipoprotein cholesterol（LDL-C） and high density lipoprotein（HDL） were examined,and islet beta cell function index（HOMA-13） were calculated. PCR and Western blot method were used to detect the expression of pancreas GRP78, ATF4, CHOP and TRB3 protein and mRNA. Results Compared with the control group, the levels of FBG, FFA, TC, FINS, TG and LDL-C in the high fat group were significantly increased, the levels of HDL-C, GIR and HOMA-β were significantly decreased（P〈0.05 or P〈0.01） ;compared with the high fat group, the levels of HDL-C,GIR and HOMA-β in the intervention group 2 were increased（P〈0.05 or P〈0.01）. the other indicators were significantly decreased;compared with the intervention group 1, blood FGB, FFA, TC in the intervention group 2 were decreased,while the levels of GIR and HOMA-β were increased（P〈0.05）. Compared with the control group, expression of GRP78, ATF4, CHOP and TRB3 protein .and mRNA in the high fat group were significantly increased; compared with the high fat group, the expression of GRP78, ATF4, CHOP and TRB3 protein and mRNA in the intervention group 1 and 2 were gradually decreased with the liraglutide concentration increase. Conclusion Liraglutide can improve insulin resistance and protect pancreatic beta cells in a concentration-dependent manner, its mechanisms may involve in the pancreatic endoplasmic reticulum ATF4/CHOP pathway.