Roux-en-Y胃旁路术对2型糖尿病大鼠胆汁酸合成及重吸收的影响

Effect of Roux-en-Y gastric bypass on the bile acids synthesis and reabsorption in type 2 diabetic rats

目的观察Roux-en-Y胃旁路(RYGB)术对2型糖尿病(T2DM)大鼠胆汁酸合成及重吸收的影响。方法Sprague-Dawley(SD)大鼠(购自广州中医药大学实验动物中心)通过高脂饲料喂养并腹腔注射链脲佐菌素诱导T2DM,随机分为手术组(n=8)和假手术组(n=8)。手术组行RYGB术,假手术组在与手术组相同位置行胃肠横断并原位吻合。术前及术后第1、2、4、6、8周测体重和空腹血糖;术后8周留取空腹血清检测血脂及总胆汁酸水平,留取门静脉血清检测总胆汁酸水平,留取肝脏及回肠黏膜组织用反转录聚合酶链反应检测胆固醇7α羟化酶(CYP7A1)、钠依赖性胆盐转运体(ASBT)、回肠胆汁酸结合蛋白(IBABP)、有机可溶性转运二聚体α(OSTα)mRNA表达水平。两组间比较采用t检验。结果手术组术后第4、6、8周体重[(372±12)、(388±15)、408±14)g]显著低于假手术组[(398±13)、(415±14)、(431±15)g],手术组术后第2、4、6、8周空腹血糖水平[(7.9±1.9)、(7.2±1.2、(6.8±1.5)、(7.9±1.1)mmol/L]显著低于假手术组[(12.5±1.6)、(11.8±1.0)、(10.5±1.9)、(11.0±1.5)mmol/L],差异均有统计学意义(t=4.157、3.722、3.171、5.238、8.329、4.323、4.714,P<0.05);手术组血清总胆固醇、甘油三酯和游离脂肪酸水平[(1.90±0.45)、(1.98±0.38)、(1.01±0.19)mmol/L]显著低于假手术组[(2.51±0.41)、(2.66±0.44)、(1.58±0.21)mmol/L],手术组外周和门静脉血清总胆汁酸水平[(95.56±13.61)、(185.89±18.71)μmol/L]显著高于假手术组[(48.37±11.68)、(98.17±15.21)μmol/L],差异均有统计学意义(t=2.834、3.308、5.693、7.442、10.290,P<0.05);手术组与假手术组比较,肝脏CYP7A1 mRNA的表达显著下调(1.07±0.21比1.35±0.15),回肠ASBT、IBABP和OSTαmRNA的表达显著上调(1.92±0.28比1.41±0.25、1.83±0.24比1.22±0.18、1.78±0.17比1.40±0.19),差异均有统计学意义(t=3.069、3.843、5.751、4.216,P<0.05)。结论RYGB术改善T2DM大鼠糖脂代谢的作用机制可能与术后血清总胆汁酸水平升高及回肠胆汁酸重吸收增加有关。

Objective To investigate the effect of Roux-en-Y gastric bypass(RYGB)on the bile acids synthesis and reabsorption in type 2 diabetes mellitus(T2DM)rats.Methods Sprague-Dawley rats were fed on a high-fat diet and injected intraperitoneally with streptozotocin to induce T2DM models,then randomly divided into sham operation group(n=8)and RYGB group(n=8).RYGB surgery was performed in RYGB group,sham surgeries involved the same gastrointestinal transections as those in the RYGB group,and re-anastomosis was performed at the same sites.Body weight and fasting blood glucose were measured before and 1st,2nd,4th,6th,8th week after surgery.At 8th week postoperatively,fasting serum was collected for measuring lipid profiles and total bile acids level,the serums from portal vein were collected for measuring total bile acids level,and the hepatic and ileum mucosa tissues were taken to compare the mRNA expression levels of cholesterol 7α-hydroxylase(CYP7A1),apical sodium-dependent bile acid transporter(ASBT),ileum bile acid binding protein(IBABP)and organic solute transporterαdimer(OSTα)by reverse transcriptase-polymerase chain reaction.Results At 4th,6th and 8th week postoperatively,the body weight in RYGB group[(372±12),(388±15)and(408±14)g]was decreased as compared with that in sham operation group[(398±13),(415±14)and(431±15)g].At 2nd,4th,6th and 8th week postoperatively,the fasting blood glucose levels in RYGB group[(7.9±1.9),(7.2±1.2),(6.8±1.5)and(7.9±1.1)mmol/L]were decreased as compared with those in sham operation group[(12.5±1.6),(11.8±1.0),(10.5±1.9)and(11.0±1.5)mmol/L],with significant differences(t=4.157,3.722,3.171,5.238,8.329,4.323,4.714,P<0.05).In the fasting serum,total cholesterol,triglyceride and free fatty acid levels in RYGB group[(1.90±0.45),(1.98±0.38)and(1.01±0.19)mmol/L]were decreased as compared with those in sham operation group[(2.51±0.41),(2.66±0.44)and(1.58±0.21)mmol/L].In the peripheral and portal vein serum,total bile acids levels in RYGB group[(95.56±13.61)and(185.89±18.71)μmol/L]were increased as compared with those in sham operation group[(48.37±11.68)and(98.17±15.21)μmol/L],with significant differences(t=2.834,3.308,5.693,7.442,10.290,P<0.05).As compared with sham operation group,the hepatic mRNA expression of CYP7A1 in RYGB group was down-regulated(1.07±0.21 vs.1.35±0.15),and the ileal mRNA expression levels of ASBT,IBABP and OSTαin RYGB group were up-regulated(1.92±0.28 vs.1.41±0.25,1.83±0.24 vs.1.22±0.18,1.78±0.17 vs.1.40±0.19),with significant differences(t=3.069,3.843,5.751,4.216,P<0.05).Conclusion RYGB can improve the glucose and lipid metabolism in T2DM rats,the mechanism may be related with increased serum total bile acids level and enhanced reabsorption of bile acids after operation in ileum.