2型糖尿病大鼠模型GLUT4 mRNA表达的研究

目的：研究葡萄糖转运体4（GLUT4）mRNA表达在2型糖尿病胰岛素抵抗中的分子机制。方法：采用高脂高糖饲养，一次性腹腔注射链脲佐菌素（STZ）制备2型糖尿病大鼠模型。逆转录聚合酶链反应（RT-PCR）分析大鼠骨骼肌、心肌和脂肪组织中GLUT4 mRNA的表达量变化与差别。结果：正常对照组和2型糖尿病大鼠模型组GLUT4 mRNA在骨骼肌中有相对较高表达，在心肌中表达次之，在脂肪组织中表达相对偏低。2型糖尿病大鼠模型组骨骼肌中GLUT4 mRNA表达量只有对照组骨骼肌的48％、心肌的44％、脂肪组织的38％。结论：GLUT4 mRNA表达量下降导致骨骼肌、心肌和脂肪组织对葡萄糖摄取利用减少是胰岛素抵抗的重要分子基础，是诱发2型糖尿病原因之一。     

小檗碱改善2型糖尿病大鼠胰岛素抵抗与PI-3K、GLUT4蛋白相关性的研究

目的观察小檗碱对2型糖尿病大鼠骨骼肌组织磷脂酰肌醇3激酶(phosphatidylinositol-3-kinase,PI-3K)之p85亚基、葡萄糖转运子4(glucose transporter4,GLUT4)蛋白表达的影响,以探讨小檗碱改善胰岛素抵抗,防治2型糖尿病的分子机制。方法采用尾静脉注射小剂量链脲佐菌素(streptozotocin,STZ,30mg.kg-1)加高脂高热量饲料喂养的方法建立2型糖尿病大鼠模型,以小檗碱干预10wk,检测血糖和血清胰岛素,用Western blot方法检测小檗碱干预后2型糖尿病大鼠骨骼肌组织PI-3K之p85亚基、GLUT4蛋白表达水平。结果小檗碱干预的2型糖尿病大鼠骨骼肌组织PI-3K之p85亚基、GLUT4蛋白表达水平均较模型组显著增加。结论小檗碱对2型糖尿病的治疗效应可能与提高骨骼肌组织中PI-3K之p85亚基、GLUT4蛋白表达水平有关。     

二甲双胍与罗格列酮对2型糖尿病大鼠GLUT4表达的比较

目的比较二甲双胍与罗格列酮对2型糖尿病大鼠骨骼肌葡萄糖转运蛋白4(GLUT4)mRNA表达的影响.方法以低剂量链脲佐菌素(STZ)加高热量饲料喂养制作模型,灌胃给药4周,检测糖耐量、空腹血清胰岛素(Ins)及骨骼肌GLUT4 mRNA表达量的变化.结果造模后大鼠注射葡葡糖后30,60,120min血糖显著升高,空腹Ins无明显变化,骨骼肌GLUT4 mRNA表达量显著降低.两药均可使注糖后120min血糖下降;罗格列酮尚可降低空腹血糖.二甲双胍可使骨骼肌GLUT4 mRNA表达量明显升高,但罗格列酮对骨骼肌GLUT4 mRNA表达的降低无影响.结论本造模方法可导致大鼠产生类似2型糖尿病的变化,两药均可改善此模型糖耐量异常,二甲双胍的作用与增强骨骼肌GLUT4基因表达有关,而罗格列酮的作用可能与其它环节有关.     

二甲双胍与罗格列酮对2型糖尿病大鼠GLUT4表达的比较

目的　比较二甲双胍与罗格列酮对2型糖尿病大鼠骨骼肌葡萄糖转运蛋白4(GLUT4)mRNA表达的影响。方法　以低剂量链脲佐菌素(STZ)加高热量饲料喂养制作模型,灌胃给药4周,检测糖耐量、空腹血清胰岛素(Ins)及骨骼肌GLUT4mR-NA表达量的变化。结果　造模后大鼠注射葡葡糖后30, 60, 120min血糖显著升高,空腹Ins无明显变化,骨骼肌GLUT4mR-NA表达量显著降低。两药均可使注糖后120min血糖下降;罗格列酮尚可降低空腹血糖。二甲双胍可使骨骼肌GLUT4mRNA表达量明显升高,但罗格列酮对骨骼肌GLUT4mRNA表达的降低无影响。结论　本造模方法可导致大鼠产生类似2型糖尿病的变化,两药均可改善此模型糖耐量异常,二甲双胍的作用与增强骨骼肌GLUT4基因表达有关,而罗格列酮的作用可能与其它环节有关。     

笔筒草有效组分抗2型糖尿病作用机制研究

目的研究笔筒草有效组分对2型糖尿病大鼠抗氧化作用、胰岛素抵抗的影响。方法通过腹腔注射链佐霉素联合高脂饲料喂养制备2型糖尿病大鼠模型,观察其对大鼠空腹血糖(FPG)、空腹胰岛素(FINS)、胰岛素抵抗指数(HOMA-IR)、血清超氧化物歧化酶(SOD)活性、丙二醛(MDA)、及葡萄糖转运蛋白4(GLUT4)的影响。结果与模型组比较,笔筒草乙醇组分及乙酸乙酯组分均可显著降低糖尿病大鼠FPG、FINS及HOMA-IR,明显升高骨骼肌GLUT4表达水平,与模型组相比,差异有统计学意义(P0.05);与乙酸乙酯组分不同之处在于,乙醇组分还能升高SOD及降低MDA含量,差异有统计学意义(P0.05)。结论笔筒草乙醇及乙酸乙酯组分降血糖机制可能与改善机体对胰岛素的敏感性,调控骨骼肌GLUT4表达水平,维持胰岛细胞的正常结构和功能密切相关,其中笔筒草乙醇组分还具有清除自由基和提高机体抗氧化能力等作用。     

NIDDM大鼠骨骼肌组织GLUT4mRNA表达及其与胰岛素分泌关系的实验研究

目的 观察非胰岛素依赖型糖尿病（NIDDM）大鼠骨骼肌葡萄糖转运体4（glucose transporter4,GLUT4)mRNA表达及其与胰岛素分泌的关系。方法 制备NIDDM大鼠模型,用Northern blot方法测定骨骼肌组织中GLUT4mRNA表达量;放射免疫法测定血清胰岛素含量;免疫组化法观察胰岛素阳性β细胞。结果 NIDDM大鼠骨骼肌GLUT4mRNA表达显低下,仅为对照组的45％（P＜0.01);其空腹基础胰岛素水平正常,但葡萄糖耐量试验胰岛素水平较对照组明显降低,2h胰岛素分泌有延迟现象;免疫组化实验NIDDM大鼠胰岛体积减少一半以上,胰岛素阳性β细胞数量明显减少。结论 NIDDM大鼠骨骼肌GLUT4mRNA表达量低下,该反应与体内胰岛素分泌水平呈现一定的正相关性。     

恒顺降糖胶囊对2型糖尿病大鼠胰岛素抵抗的影响

目的观察恒顺降糖胶囊(Hengshun Jiangtang capsules,HS)对2型糖尿病大鼠胰岛素抵抗的影响。方法对连续10d灌胃给予脂肪乳的大鼠腹腔注射四氧嘧啶,72h后血糖值≥16.7mmol·L-1者为2型糖尿病大鼠模型;给药28d,观察HS对空腹血糖(FBG)、糖耐量(OGTT)、空腹血清胰岛素(FINS)、胰岛素耐量(ITT)和胰岛素抵抗指数(Homa-IR)的影响。结果HS能改善2型糖尿病大鼠的OGTT和ITT,降低FGB,FINS和Homa-IR。结论HS明显降低2型糖尿病大鼠的胰岛素血症,改善其对胰岛素的抵抗。     

脂联素影响骨骼肌胰岛素抵抗模型中葡萄糖转运蛋白4表达的研究

目的：通过建立骨骼肌L6细胞胰岛素抵抗模型,探讨骨骼肌L6细胞中脂联素（ APN）的分泌,以及脂联素对骨骼肌胰岛素抵抗模型中葡萄糖转运蛋白4（GLUT4）表达的影响。方法（1）体外培养大鼠L6成肌细胞,诱导分化后,给予不同浓度的棕榈酸（PA）,测定不同时间细胞培养上清液葡萄糖浓度,观察PA对L6细胞摄取葡萄糖的影响,建立胰岛素抵抗模型;（2）根据实验条件的不同分为三组：NC组（正常对照组,即骨骼肌L6细胞组）;IR组（胰岛素抵抗模型组）;IR＋PIO组（胰岛素抵抗模型＋吡格列酮组）。应用Western blot方法分别测定上述三组APN和GLUT4表达水平。结果（1）0．4 mmol· L^-1的棕榈酸在作用12、24、36 h以及0．6～0．8 mmol· L^-1棕榈酸作用8～36 h后,细胞培养上清液中葡萄糖含量,明显高于对照组。胰岛素抵抗模型建立;（2）Western blot结果显示：①与NC组比较,IR组APN和GLUT4表达均减少,差异有统计学意义;②与IR组比较,IR＋PIO组其APN和GLUT4表达均增加,差异有统计学意义。结论（1）大鼠L6成肌细胞培养并诱导分化后,经过一定条件下PA刺激,可以建立胰岛素抵抗模型;（2）大鼠L6细胞可分泌和表达脂联素,骨骼肌源性脂联素上调L6细胞GLUT4的表达;（3）吡格列酮作为PPAR-γ激动剂,可增加大鼠L6细胞脂联素的分泌,进而改善胰岛素敏感性。     

血管紧张素1-7对2型糖尿病大鼠胰岛素抵抗的影响及机制

目的研究血管紧张素1-7[Ang-(1-7)]对2型糖尿病大鼠胰岛素抵抗的影响及机制。方法 36只8周龄健康雄性Wistar大鼠随机数字表法分为正常对照组、糖尿病对照组、Ang-(1-7)干预组。糖尿病对照组和Ang-(1-7)干预组以高脂高热量饮食喂养8周,一次性腹腔注射链脲佐菌素30 mg/kg,建立2型糖尿病大鼠模型。成模后,Ang-(1-7)干预组大鼠颈部皮下注射Ang-(1-7)300μg·kg-1·d-1,糖尿病对照组和正常对照组注射等体积的0.9%氯化钠注射液。干预8周,监测空腹血糖(FPG),检测血清空腹胰岛素(FINS)及AngⅡ含量,计算稳态模型胰岛素抵抗指数(HOMA-IR),用蛋白质印迹法检测大鼠附睾旁脂肪组织中葡萄糖转运蛋白4(GLUT4)的表达。结果与正常对照组相比,糖尿病对照组大鼠FPG显著升高,FINS减少了49.1%,AngⅡ含量、HOMA-IR分别增加了34.1%和84.6%(均P<0.05)。而Ang-(1-7)干预后与糖尿病对照组相比,FPG下降,FINS增加了32.9%,AngⅡ、HOMA-IR分别降低了14.3%和11.6%(均P<0.05)。糖尿病对照组大鼠GLUT4的表达量明显低于正常对照组,Ang-(1-7)干预后GLUT4表达量明显升高(P<0.05)。结论 Ang-(1-7)可通过增加脂肪组织中GLUT4的含量,改善胰岛素抵抗,从而发挥抗糖尿病作用。     

补肾通脉方对Ⅱ型糖尿病大鼠骨骼肌胰岛素受体表达的影响

目的：探讨补肾通脉方对Ⅱ型糖尿病大鼠骨骼肌胰岛素受体表达的影响。方法：采用小剂量链脲佐菌素加高热量饲养方法建立Wistar大鼠Ⅱ型糖尿病模型，并随机分为模型组、中药组及西药组(分别用补肾通脉方和二甲双胍干预8周)，另设正常组(喂以普通饲料)；检测骨骼肌组织中三酰甘油(mTG)含量；以逆转录聚合酶链式反应(RT-PCR)检测骨骼肌组织胰岛素受体(InsR)mRNA的表达水平。结果：与正常组相比，模型组骨骼肌组织mTG水平明显升高(P＜0.01)，而InsR mRNA表达显著减少(P＜0．01)；与模型组比较，中药组骨骼肌组织mTG水平显著降低(P＜0．01)，InsR mRNA表达则显著增提高(P＜0.01)。结论：补肾通脉方改善胰岛素抵抗的作用机制可能与其上调Ⅱ型糖尿病大鼠骨骼肌组织InsR mRNA表达水平有关。     

Effects of losartan in combination with or without exercise on insulin resistance in Otsuka Long–Evans Tokushima Fatty rats

Hypertension often complicates type 2 diabetes mellitus, and angiotensin converting enzyme inhibitor treatment has been shown to improve insulin resistance in such cases. However, the effect of angiotensin II type-1 (AT₁) receptor antagonists on insulin resistance is still controversial. To gain further information on this effect, we examined the effect of losartan on insulin resistance in Otsuka Long–Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus. Losartan administration alone lowered systolic blood pressure, but did not improve oral glucose tolerance test or insulin resistance in OLETF rats. However, the administration of losartan with exercise significantly improved both systolic blood pressure and insulin resistance relative to control OLETF rats. On the other hand, losartan treatment, regardless of exercise, increased glucose uptake in excised soleus muscle and fat cells. To explore the beneficial effect of losartan on skeletal muscle glucose uptake, we examined intracellular signaling of soleus muscle. Although Akt activity and glucose transporter type 4 (GLUT4) expressions were not affected by losartan with or without exercise, extracellular signal-regulated kinase (ERK1/2) and p38 mitogen-activated protein (MAP) kinase activities were increased by both interventions. These results indicate that angiotensin AT₁ receptor antagonist improved local insulin resistance, but not systemic insulin resistance. These findings may explain the controversy over the effect of angiotensin AT₁ receptor antagonists on insulin resistance in clinical use. The enhancing effect of angiotensin AT₁ receptor antagonist on skeletal muscle glucose uptake may be attributable to MAP kinase activation or other mechanisms rather than phosphatidylinositol 3-kinase activation.     

虫草多糖对2型糖尿病小鼠InsR／IRS-1通路及糖代谢的影响

目的：观察虫草多糖对2型糖尿病小鼠InsR／IRS—1通路及糖代谢的影响。方法：采用高脂饲料联合腹腔注射小剂量链脲佐菌素（STZ,25mg·kg-1）建立胰岛素抵抗2型糖尿病模型,每日给予不同剂量虫草多糖（200,400mg·kg-1）治疗,28d后．免疫印迹法检测实验小鼠骨骼肌内胰岛素受体（1nsR）、胰岛素受体底物（IRS-1）及葡萄糖转运蛋白（GLUT4）的表达水平。检测肝脏葡萄糖激酶（GK）、磷酸果糖激酶（PFK）活性水平。结果：虫草多糖治疗组可显著改善糖尿病小鼠InsR／IRS一1及GLUT4蛋白的畀常表达（P〈0．05）;并呈剂量依赖性地增强小鼠肝脏GK及PFK酶活性,与糖尿病模型组比较差畀有统计学意义（P〈0．05或0．01）。结论：虫草多糖可增强胰岛素信号通路敏感性,改善葡萄糖代谢,从而缓解糖尿病小鼠胰岛素抵抗及高血糖症状,为胰岛素抵抗2型糖尿病的临床治疗提供新的依据。     

Bis(alpha-furancarboxylato)oxovanadium(IV) prevents and improves dexamethasone-induced insulin resistance in 3T3-L1 adipocytes

Previous studies showed that bis(alpha-furancarboxylato)oxovanadium(IV) (BFOV), an orally active anti-diabetic organic vanadium complex, could improve insulin resistance in animals with type 2 diabetes. The present study has been carried out to evaluate the effects of BFOV on insulin-resistant glucose metabolism using dexamethasone-treated 3T3-L1 adipocytes as an in-vitro model of insulin resistance. The results showed that BFOV, similar to vanadyl sulfate and rosiglitazone, caused a concentration-dependent increase in glucose consumption by insulin-resistant adipocytes. Moreover, BFOV enhanced the action of insulin and completely prevented the development of insulin resistance induced by dexamethasone, leading to glucose consumption equal to that by normal cells. In addition, dexamethasone reduced the mRNA expression of insulin receptor substrate 1 (IRS-1) and glucose transporter 4 (GLUT4) in 3T3-L1 adipocytes, while BFOV normalized the expression of IRS-1 and GLUT4. These findings suggest that BFOV prevents and improves dexamethasone-induced insulin resistance in 3T3-L1 adipocytes by enhancing expression of IRS-1 and GLUT4 mRNA.     

Karanjin from Pongamia pinnata induces GLUT4 translocation in skeletal muscle cells in a phosphatidylinositol-3-kinase-independent manner

Insulin-stimulated glucose uptake in skeletal muscle is decreased in type 2 diabetes due to impaired translocation of insulin-sensitive glucose transporter 4 (GLUT4) from intracellular pool to plasma membrane. Augmenting glucose uptake into this tissue may help in management of type 2 diabetes. Here, the effects of an identified antihyperglycemic molecule, karanjin, isolated from the fruits of Pongamia pinnata were investigated on glucose uptake and GLUT4 translocation in skeletal muscle cells. Treatment of L6-GLUT4myc myotubes with karanjin caused a substantial increase in the glucose uptake and GLUT4 translocation to the cell surface, in a concentration-dependent fashion, without changing the total amount of GLUT4 protein and GLUT4 mRNA. This effect was associated with increased activity of AMP-activated protein kinase (AMPK). Cycloheximide treatment inhibited the effect of karanjin on GLUT4 translocation suggesting the requirement of de novo synthesis of protein. Karanjin-induced GLUT4 translocation was further enhanced with insulin and the effect is completely protected in the presence of wortmannin. Moreover, karanjin did not affect the phosphorylation of AKT (Ser-473) and did not alter the expression of the key molecules of insulin signaling cascade. We conclude that karanjin-induced increase in glucose uptake in L6 myotubes is the result of an increased translocation of GLUT4 to plasma membrane associated with activation of AMPK pathway, in a PI-3-K/AKT-independent manner.     

谷氨酸钠与高糖饮食对2型糖尿病大鼠的代谢障碍和记忆障碍的影响

研究味精(MSG)和高蔗糖饮食(HSD)的组合建立2 型糖尿病(T2DM)的实验动物模型的可行性,并探究谷氨酸钠与高糖饮食对2 型糖尿病患者的血管功能障碍和记忆障碍的影响.对雄性Wistar 大鼠(20～30 g)注射味精(2 或4 mg/g,腹腔注射4 d),实验组大鼠再喂食HSD,对照组则喂食淀粉饮食(SFD)15...     

Exercise-induced galanin release facilitated GLUT4 translocation in adipocytes of type 2 diabetic rats

Although galanin has been shown to increase insulin sensitivity in skeletal muscle of rats, there is no literature available about the effect of galanin on Glucose Transporter 4 (GLUT4) translocation from intracellular membrane pools to plasma membranes in adipocytes of type 2 diabetic rats. In the present study M35, a galanin antagonist was used to elucidate whether exercise-induced galanin release increased GLUT4 translocation in adipocytes of streptozotocin-induced diabetic rats. The present findings showed that plasma galanin levels after swimming training in all four trained groups were higher compared with each sedentary control. M35 treatment had an inhibitory effect on glucose infusion rates in the euglycemic-hyperinsulinemic clamp test and GLUT4 mRNA expression levels in adipocytes. Moreover, M35 treatment reduced GLUT4 concentration in both plasma membranes and total cell membranes. The ratios of GLUT4 contents in plasma membranes to total cell membranes in four drug groups were lower compared with each control. These data demonstrate a beneficial role of endogenous galanin to transfer GLUT4 from internal stores to plasma membranes in adipocytes of type 2 diabetic rats. Galanin plays a significant role in regulation of glucose metabolic homeostasis and is an important hormone relative to diabetes.