5-氨基乙酰丙酸对内质网应激水平及肥胖小鼠糖代谢的影响

Effects of 5-Amino Levulinic Acid on Endoplasmic Reticulum Stress and Glucose Metabolism in Obese Mice

[目的]探讨5-氨基乙酰丙酸(5-ALA)对内质网应激水平及肥胖小鼠糖代谢的影响及相关分子机制。[方法]将10只8周龄C57BL/6J小鼠适应性喂养1周后,高脂饲料喂养16周诱导造模肥胖小鼠,将肥胖小鼠随机分为5-ALA处理组[5-ALA灌胃5 mg/(kg·d)]和对照组[磷酸盐缓冲液(PBS)灌胃1mL/(kg·d)],连续9周,期间每周于空腹12 h后尾静脉取血检测小鼠的空腹血糖。9周后分离小鼠的肝脏和附睾脂肪组织提取RNA和蛋白,检测小鼠肝脏和脂肪组织中内质网应激相关基因C/EBP同源蛋白(CHOP)、X-盒结合蛋白1s(XBP-1s)、重链结合蛋白(Bi P)、内质网Dnaj同系物4(ERdj4)的表达水平。[结果]5-ALA处理小鼠空腹血糖于第5周[(6.40±0.35)mmol/L]开始下降,波动变小,第7周5-ALA处理组空腹血糖水平[(6.02±0.17)mmol/L]低于对照组[(6.54±0.05)mmol/L](P<0.05)。实时聚合酶链反应(real-time PCR)结果显示,5-ALA可抑制由于肥胖导致的脂肪组织中XBP-1s的高表达(5-ALA处理组2-△△CT为0.029±0.017,对照组为0.029±0.006),P<0.05;western blotting结果亦显示5-ALA处理组小鼠XBP-1s水平低于对照组。[结论]5-ALA可能通过抑制白色脂肪组织中内质网应激通路IRE1-XBP-1通路缓解内质网应激水平,改善小鼠的血糖代谢。

[ Objective ] To examine the relationship of 5-amino levulinic acid （5-ALA） with endoplasmic reticulum stress and glucose metabolism and potential related molecular mechanisms. [ Methods ] Ten C57BL/6J mice at eight weeks of age were induced to establish obese mice model by 16-week high fat diet after one week of adaptive feeding, then randomly divided into an 5-ALA group [5 mg/（kg · d）] and a control group [phosphate buffered saline 1 mL/（kg · d）], for nine consecutive weeks. During the intragastric administration, blood samples were collected from tail vein after 12 h of fasting for measuring fasting blood glucose levels. Nine weeks later, the mice liver and epididymal adipose tissues were separated to extract RNA and protein and measure the expressions of C/EBP homologous protein （CHOP）, X-box binding protein Is （XBP-ls）, binding immunoglobulin protein （BiP）, and endoplasmic reticulum DnaJ protein family member 4 （ERdj4）. [ RosulIs ] Compared with the control group [（6.54 ± 0.05）mmol/L], the fasting blood glucose levels in the mice treated with 5-ALA were lowered from week 5 [（6.40 ± 0.35） mmol/L] with little variation and showed a significant decrease at week 7 [（6.02 ± 0.17） mmol/L] （P 〈 0.05）. The real-time polymerase chain reaction results showed that 5-ALA significantly inhibited the increased mRNA levels of XBP-1 s induced by obesity 2-△△CT for the 5-ALA group was 0.029 ± 0.017, 2-△△CTfor the control group was 0.029 ±0.006, P 〈 0.05）. The western blotting results indicated that the expression of XBP-ls was lower in the 5-ALA group than in the control group. [ Conclusion ] 5-ALA could improve glucose metabolism in mice by inhibiting endoplasmic retieulum stress via IRE1-XBP-1 pathway in white adipose tissues.