Effect of insulin in combination with selenium on blood glucose and GLUT4 expression in skeletal muscle of streptozotocin-induced diabetic rats

Objective To evaluate the effect of low-dose insulin [1 U/(kg·d)] in combination with selenium [180 g/(kg·d)] on general physiological parameters and glucose transporter (GLUT4) level in skeletal muscle of streptozotocin (STZ)-induced diabetic rats. Methods Diabetic rats were treated with insulin,selenium,and insulin and selenium in combination for four weeks. The level of blood glucose was determined using One Touch SureStep Blood Glucose meter and the level of GLUT4 in skeletal muscle was examined by immunoblotting and immunohistochemistry. Results Our data showed that insulin in combination with selenium could significantly lower blood glucose level and restore the disturbance in GLUT4 level in skeletal muscle. Treatment with insulin was only partially effective in restoring diabetic alterations. Conclusion It can be concluded that there is a synergistic action between insulin and selenium,and that treatment of diabetic rats with combined doses of insulin and selenium is effective in the normalization of blood glucose level and correction of altered GLUT4 distribution in skeletal muscle of diabetic rats.

Synaptotagmins family affect glucose transport in retinal pigment epithelial cells through their ubiquitination-mediated degradation and glucose transporter-1 regulation

BACKGROUND Synaptotagmins(SYTs)are a family of 17 membrane transporters that function as calcium ion sensors during the release of Ca2+-dependent neurotransmitters and hormones.However,few studies have reported whether members of the SYT family play a role in glucose uptake in diabetic retinopathy(DR)through Ca2+/glucose transporter-1(GLUT1)and the possible regulatory mechanism of SYTs.AIM To elucidate the role of the SYT family in the regulation of glucose transport in retinal pigment epithelial cells and explore its potential as a therapeutic target for the clinical management of DR.METHODS DR was induced by streptozotocin in C57BL/6J mice and by high glucose medium in human retinal pigment epithelial cells(ARPE-19).Bioinformatics analysis,reverse transcriptase-polymerase chain reaction,Western blot,flow cytometry,ELISA,HE staining,and TUNEL staining were used for analysis.RESULTS Six differentially expressed proteins(SYT2,SYT3,SYT4,SYT7,SYT11,and SYT13)were found between the DR and control groups,and SYT4 was highly expressed.Hyperglycemia induces SYT4 overexpression,manipulates Ca2+influx to induce GLUT1 fusion with the plasma membrane,promotes abnormal expression of the glucose transporter GLUT1 and excessive glucose uptake,induces ARPE-19 cell apoptosis,and promotes DR progression.Parkin deficiency inhibits the proteasomal degradation of SYT4 in DR,resulting in SYT4 accumulation and enhanced GLUT1 fusion with the plasma membrane,and these effects were blocked by oe-Parkin treatment.Moreover,dysregulation of the myelin transcription factor 1(Myt1)-induced transcription of SYT4 in DR further activated the SYT4-mediated stimulus-secretion coupling process,and this process was inhibited in the oe-MYT1-treated group.CONCLUSION Our study reveals the key role of SYT4 in regulating glucose transport in retinal pigment epithelial cells during the pathogenesis of DR and the underlying mechanism and suggests potential therapeutic targets for clinical DR.

Effect of iron supplementation on glucose transporter 4 expression in adipose tissue and skeletal muscle of pregnant rats

Objective: The main goal of the present study was to investigate the effect of iron supplementation on glucose transporter 4 expressions in adipose tissue and skeletal muscle in female rats during pregnancy. Methods: Twenty-four pregnant Sprague-Dawley rats were randomly divided into 2 groups: a control group with a standard diet (containing iron 150 mg/kg) and an iron-supplementation group with a high-iron diet (containing iron 700 mg/kg) from day 0 to day 21 of pregnancy. Intraperitoneal glucose tolerance test was performed on gestational day 19. On gestational day 21, all of the pregnant rats from each group were sacrificed. The mean neonatal weights were measured and samples of maternal intraabdominal adipose tissue and skeletal muscle were taken to measure the expression of Glucose Transporter 4 (GLUT4) mRNA and protein. Results: Glucose tolerance decreased significantly in the iron supplementation group compared to the control group. The mean neonatal weights in the iron supplementation group were higher than that in the control group. Levels of GLUT4 mRNA in the adipose tissue were reduced by the administrations of high-iron diet. The skeletal muscle GLUT4 mRNA levels were not changed significantly by iron supplementation. Expression of GLUT4 protein both in the adipose tissue and skeletal muscle reduced significantly. Conclusion: These results suggest that iron supplementation during pregnancy would increase neonatal weights and could decrease maternal glucose tolerance by interfering GLUT4 expression in adipose tissue and skeletal muscle of rats.

黄连温胆汤对代谢综合征大鼠胰岛素抵抗、糖脂代谢及GLUT-4的影响

目的通过观察代谢综合征大鼠的各项指标变化,探讨黄连温胆汤对MS大鼠胰岛素抵抗、糖脂代谢及GLUT-4的影响。方法选用54只SD大鼠建立代谢综合征模型,选用高糖高脂高盐饲料方式喂养,造模20周。造模成功后,在实验组大鼠中筛选符合MS标准的大鼠44只,按照造模成功后各组情况,分别为模型组8只、格华止组8只、黄连温胆汤高、中剂量组、低剂量组各9只,对照组中符合标准大鼠8只,在每日1次固定时间给予各组大鼠进行灌胃,干预4周。实验过程中测量大鼠体重、内脏脂肪、腹围、心率、血压等一般情况,测量离心血浆空腹血糖、血清胰岛素、血脂等指标,计算HOMA-IR,对实验结果进行讨论评价。结果造模20周后,与对照组相比较,实验组大鼠空腹血清胰岛素、甘油三酯、总胆固醇水平均明显升高(P<0.05),高密度脂蛋白、GLUT-4水平下降(P<0.05),代表造模成功。给药进行干预4周后,与模型组相比较,黄连温胆汤高剂量组与格华止组大鼠的体质量、LEE、内脏脂肪重量、脂肪/体质量明显降低(P<0.05),在血糖、血脂(TG、TC、LDL-C)、HOMR-IR、空腹血清胰岛素、FFA等水平含量以上两组也较模型组下降明显(P<0.05);黄连温胆汤高剂量组大鼠血压明显降低(P<0.05),其余组均无明显变化;IRS-1、P85、GLUT-4在黄连温胆汤高剂量组和格华止组较模型组明显升高(P<0.05)。结论黄连温胆汤能有效降低代谢综合征大鼠血糖、血脂、空腹血清胰岛素以及HOMA-IR水平,具有降压、降糖、降脂、降低血清胰岛素水平的作用,能够有效改善代谢综合征大鼠的代谢异常,具有一定的预防代谢综合征发生的作用;黄连温胆汤对降低代谢综合征大鼠TC、TG、FFA的水平具有显著作用,对改善代谢综合征大鼠的糖脂代谢存在一定的价值,减轻胰岛素抵抗和调节糖脂代谢可能是黄连温胆汤对代谢综合征的主要调节方式,通过抑制FFA、IRS-1、P85水平的表达,达到GLUT-4水平回调,调节并改善代谢综合征。

Nuciferine relieves type 2 diabetes mellitus via enhancing GLUT4 expression and translocation

Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporter 4(GLUT4)in L6 cells and the changes in intracellular Ca^(2+)levels in real time,and related protease inhibitors combined with western blotting were used to explore the mechanism of nuciferine.Meanwhile,KK-Ay mice,the spontaneous type 2 diabetic mice,were used to evaluate the in vivo activity of nuciferine.In this study,the in vitro studies indicated that nuciferine-induced GLUT4 translocation was regulated by G protein-PLC-PKC and AMPK pathways and nuciferine-enhanced intracellular Ca^(2+)was mediated by G protein-PLC-IP3-IP3R pathway,the increase in intracellular Ca^(2+)caused by nuciferine was not directly related to GLUT4 translocation,but both promote glucose uptake.The in vivo results suggested that nuciferine ameliorated weight gain induced by high-fat diet,abnormal lipid metabolism and the symptoms of insulin resistance in KK-Ay diabetic mice.Western blot results suggested that nuciferine increased AMPK and PKC phosphorylation levels in skeletal muscle and liver,and enhanced GLUT4 expression in skeletal muscle.Taken together,this research showed that nuciferine has the non-negligible potential in the treatment of type 2 diabetes mellitus.

Anti-diabetic potential of apigenin,luteolin,and baicalein via partially activating PI3K/Akt/GLUT-4 signaling pathways in insulin-resistant HepG2 cells

Dietary flavonoids are abundant in natural plants and possess multiple pharmacological and nutritional activities.In this study,apigenin,luteolin,and baicalein were chosen to evaluate their anti-diabetic effect in high-glucose and dexamethasone induced insulin-resistant(IR)HepG2 cells.All flavonoids improves the glucose consumption and glycogen synthesis abilities in IR-HepG2 cells via activating glucose transporter protein 4(GLUT4)and phosphor-glycogen synthase kinase(GSK-3β).These fl avonoids signifi cantly inhibited the production of reactive oxygen species(ROS)and advanced glycation end-products(AGEs),which were closely related to the suppression of the phosphorylation form of NF-κB and P65.The expression levels of insulin receptor substrate-1(IRS-1),insulin receptor substrate-2(IRS-2)and phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)pathway in IR-HepG2 cells were all partially activated by the fl avonoids,with variable effects.Furthermore,the intracellular metabolic conditions of the fl avonoids were also evaluated.

剑白香猪葡萄糖转运蛋白4 cDNA的克隆及序列分析

为了在基因水平上给动物的营养代谢研究提供基础性资料,为系统研究剑白香猪这一优质猪种提供参考,以剑白香猪肌肉组织中的总RNA为模板,克隆了剑白香猪的GLUT-4cDNA序列,并对其序列进行了分析。结果表明:克隆片段总长为1 616bp,包含一个长1 530bp的开放阅读框(ORF),编码509个氨基酸残基的蛋白;该蛋白的相对分子质量为54.809 4kDa,等电点为6.98,包含30个功能位点,即3个N-糖基化位点、1个cAMP和cGMP依赖性蛋白激酶磷酸化位点、4个酪蛋白激酶Ⅱ磷酸化位点、2个酪氨酸激酶磷酸化位点、4个蛋白激酶C磷酸化位点、2个酰胺化位点、12个N-豆蔻酰化位点、1个糖转运蛋白signature 1位点和1个糖转运蛋白signature 2位点;剑白香猪与牛、兔、小家鼠、人、马、黑猩猩、褐家鼠、非洲爪蟾GLUT-4基因编码序列的同源性分别为91.76%、90.52%、87.91%、90.52%、92.29%、90.46%、87.52%和65.82%,氨基酸序列的同源性分别为94.7%、95.68%、94.11%、95.09%、94.89%、95.28%、94.5%和68.31%。

糖耐康改善KKAy小鼠Toll样受体4通路及葡萄糖转运子4的作用机制研究

目的:观察中药糖耐康对KKAy小鼠血糖、体质量及Toll样受体4(TLR4)通路中白细胞介素6(IL-6)、核因子κB激酶β抑制物(IKKβ)及葡萄糖转运蛋白4(GluT4)影响,分析其改善2型糖尿病的可能作用机制。方法:选取无特定病原体(SPF)级自发性2型糖尿病动物KKAy小鼠及C57BL/6J小鼠,给予高脂饲料喂养,连续8周给药,评价血糖及体质量。并采用半定量酶联免疫吸附测定(ELISA)检测血浆中IL-6及GluT4的水平。蛋白质印迹法检测肝组织TLR4蛋白表达、肌肉组织IKKβ蛋白表达水平。结果:中药糖耐康高剂量组,能够显著降低血糖水平(P<0.05),具有一定抑制体质量增长的趋势。同时能够下调IL-6水平,上调GluT4的水平(P<0.01,P<0.05),抑制TLR4及IKKβ蛋白表达(P<0.01,P<0.05)。结论:糖耐康可能通过下调脂多糖(LPS)介导的TLR4通路中关键炎症介质的水平,减轻低度炎症反应,在一定程度上抑制炎症级联效应,同时提高胰岛素信号转导受体后途径中GluT4的转位及活性水平,共同达到改善胰岛素抵抗状态的作用。

Anti-Hyperglycemic Effect of Single Administered Gardeniae Fructus in Streptozotocin-Induced Diabetic Mice by Improving Insulin Resistance and Enhancing Glucose Uptake in Skeletal Muscle

The mechanisms of Gardeniae Fructus (GF) for anti-hyperglycemic action were demonstrated in streptozotocin (STZ)-diabetic mice. Six hours after single intraperitoneal administration of GF (300 mg/kg) or H2O into 3 hour-fasted STZ-diabetic mice, glucose and insulin tolerances were assessed by intraperitoneal glucose (1.5 g/kg) tolerance test (IPGTT) and intraperitoneal insulin (0.65 U/kg) tolerance test (IPITT), respectively. Effects of GF on insulin signaling pathways in soleus muscle such as glucose uptake, expression of glucose transporter 4 (GLUT4) in the plasma membrane and phosphorylation of Akt (P-Akt) in cytosolic fraction were examined in STZ-diabetic mice. In IPGTT test, GF significantly accelerated clearance of exogenous glucose and its glucose-lowering action was greater than H2O-treated controlin STZ-diabetic mice. GF also promoted an exogenous glucose-increased insulin level in STZ-diabetic mice. In IPITT test, GF decreased glucose level to the greater extent than H2O-treated control in STZ-diabetic mice. Furthermore, GF significantly decreased high HOMA-IR in STZ-diabetic mice from 21.6 ± 2.4 to 12.4 ± 1.9 (mg/dl × μU/ml). These results implied that GF improved insulin resistance in STZ-diabetic mice. GF increased glucose uptake of soleus muscle 1.5 times greater than H2O-treated control in STZ-diabetic mice. GF enlarged insulin (10 nmol/ml)-increased glucose uptake to 1.8 time-greater. Correspondingly, GF increased expression of GLUT4 in the plasma membrane of soleus muscle to 1.4 time-greater, and P-Akt in the cytosolic fraction of soleus muscle to 1.9 time-greater than those in H2O-treated control. In conclusion, the improvement of GF on insulin resistance is associated with the repair of insulin signaling via P-Akt, GLUT4 and glucose uptake pathway in soleus muscle of STZ-diabetic mice.

A Triterpene Glycoside Fraction, TG from <i>Gymnema sylvestre</i>Ameliorates Insulin Resistance by Stimulating Glucose Uptake in 3T3L1 Adipocytes and C2C12 Skeletal Muscle Cells

Type 2 diabetes mellitus (T2DM) which is characterized by insulin resistance in muscle and adipose tissues is a major problem worldwide. Plant based medications are well known from ancient times for possessing antidiabetic properties. Amongst them, Gymnema sylvestre (GS) is one such antidiabetic medicinal plant which has been used traditionally over the years for the treatment of T2DM. The aim of the present study was to investigate the effect of triterpene glycoside (TG), an active fraction isolated from ethanolic extract of Gymnema sylvestre (EEGS) on a battery of targets;glucose transporter (GLUT- 4), peroxisome proliferator activator receptor gamma (PPAR-γ), adiponectin and leptin involved in glucose transport and metabolism. No cytotoxic effects were observed in treated cells up to 600 μg/ml of TG as measured by MTT and ROS assays. Elevation of GLUT-4 and PPAR-γ by TG in association with glucose transport supported the upregulation of glucose uptake at concentrations of 50 and 100 μg/ml respectively. Additionally, TG showed higher expression of adiponectin and leptin, confirming the favorable pharmacological effect of TG on insulin resistance. The results were comparable to the known antidiabetic drug pioglitazone and commercial standard DAG. Thus TG could be considered as a safe nutraceutical candidate/functional phytoingredient in amelioration of insulin resistance.

Involvement of glucose transporter 4 in ovarian development and reproductive maturation of Harmonia axyridis(Coleoptera:Coccinellidae)

Glucose is vital to embryogenesis,as are glucose transporters.Glucose transporter 4(Glut4)is one of the glucose transporters,which is involved in rapid uptake of glucose by various cells and promotes glucose homeostasis.Although energy metabolism in insect reproduction is well known,the molecular mechanism of Glut4 in insect reproduction is poorly understood.We suspect that Glut4 is involved in maintaining glucose concentrations in the ovaries and affecting vitellogenesis,which is critical for subsequent oocyte maturation and insect fertility.Harmonia axyridis(Pallas)is a model organism for genetic research and a natural enemy of insect pests.We studied the influence of the Glut4 gene on the reproduction and development of H.axyridis using RNA interference technology.Reverse transcription quantitative polymerase chain reaction analysis revealed that HaGlut4 was most highly expressed in adults.Knockdown of the HaGlut4 gene reduced the transcript levels of HaGlut4,and the weight and number of eggs produced significantly decreased.In addition,the transcript levels of vitellogenin receptor and vitellogenin in the fat bodies and the ovaries of H.axyridis decreased after the interference of Glut4,and decreased the triglyceride,fatty acid,total amino acid and adenosine triphosphate content of H.axyridis.This resulted in severe blockage of ovary development and reduction of yolk formation;there was no development of ovarioles in the developing oocytes.These changes indicate that a lack of HaGlut4 can impair ovarian development and oocyte maturation and result in decreased fecundity.

Glucose transporter 4 can be inserted in the membrane without exposing its catalytic site for photolabeling from the medium

Insulin stimulates the production of PI(3,4,5)P3 in muscle cells, and this is required to stimulate GLUT4 fusion with the plasma membrane. Introduction of exogenous PI(3,4,5)P3 to muscle cells recapitulates insulin's effects on GLUT4 fusion with the plasma membrane, but not glucose uptake. This study aims to explore the mechanism behind this difference. In L6-GLUT4myc muscle cells, the availability of the GLUT4 intracellular C-terminus and extracellular myc epitopes for immunoreactivity on plasma membrane lawns was detected with the corresponding antibody. The availability of the active site of GLUT4 from extracellular medium was assessed by affinity photolabeling with the cell impermeant compound Bio-LC-ATB-BMPA. 100nmol/L insulin and 10μmol/L PI(3,4,5)P3 caused myc signal gain on the plasma membrane lawns by 1.64-fold and 1.58-fold over basal, respectively. Insulin, but not PI(3,4,5)P3, increased photolabeling of GLUT4 and immunolabeling with C-terminus antibody by 2.47-fold and 2.04-fold over basal, respectively. Upon insulin stimulation, the C-terminus signal gain was greater than myc signal gain (2.04-fold vs. 1.64-fold over basal, respectively) in plasma membrane lawns. These results indicate that (i) PI(3,4,5)P3 does not make the active site of GLUT4 available from the extracellular surface despite causing GLUT4 fusion with the plasma membrane; (ii) the availability of the active site of GLUT4 from the extracellular medium and availability of the C-terminus from the cytosolic site are correlated; (iii) in addition to stimulating GLUT4 translocation, insulin stimulation displaces a protein which masks the GLUT4 C-terminus. We propose that a protein which masks the C-terminus also prevents the active site from being available for photolabelling and possibly glucose uptake after treatment with PI(3,4,5)P3.

胃肠转流术改善糖尿病大鼠胰岛素抵抗和增加外周脂肪和肌肉组织中GLUT-4基因表达

目的观察并分析胃肠转流术对2型糖尿病(T2DM)大鼠血糖、胰岛素抵抗指数及葡萄糖转运蛋白4(GLUT-4)基因表达的影响及可能机制。方法通过高脂饮食及腹腔注射链脲佐菌素制备T2DM大鼠模型,成模后分为T2DM胃肠转流术组(DRO组)和T2DM假手术组(DSO组),SD大鼠胃肠转流术组(NRO组)和SD大鼠假手术组(NSO组)。测定术前、术后4周、术后8周各组空腹血糖(FBG)、空腹血清胰岛素(Fins)及胰岛素抵抗指数(IR);术后8周处死大鼠,取外周脂肪和肌肉组织检测GLUT-4基因表达。结果DRO组FBG及HOMA-IR术后4周较术前下降,但差异无统计学意义(P>0.05),术后8周较术前明显下降(P<0.05),同时显著低于同时间点DSO组(P<0.05),DRO组FBG仍高于NRO及NSO组(P<0.05),但HOMA-IR与NRO及NSO组相比差异无统计学意义(P>0.05)。术后8周,DRO组外周脂肪及肌肉组织中GLUT-4基因表达较DSO组明显增加(P<0.01),与NRO及NSO组相比差异无统计学意义(P>0.05)。Pearson相关性分析提示术后8周外周脂肪及肌肉组织中GLUT-4基因表达与FBG及HOMA-IR呈负相关(P<0.01)。结论胃肠转流术可改善T2DM大鼠的胰岛素抵抗、降低血糖,其机制可能与术后脂肪组织和肌肉组织中GLUT-4基因表达增高相关。

Effects of GLUT4 expression on insulin resistance in patients with advanced liver cirrhosis

Decreased glucose tolerance and diabetes are frequently observed in advanced liver cirrhosis patients and may be related to insulin resistance.Glucose transporter-4 (GLUT4),one of the most important glucose transporters,plays a key role in the development of type 2 diabetes.In order to study the mechanism of insulin resistance in liver cirrhosis patients,we measured the insulin sensitivity index and determined the GLUT4 protein and mRNA contents of skeletal muscle by Western blotting and reverse transcription-polymerase chain reaction (RT-PCR),respectively,in normal people and liver cirrhosis patients.The results showed that the levels of glucose,insulin,and C-peptide in two liver cirrhosis groups were higher and the insulin sensitivity index lower than those of the normal control group.The sensitivity of insulin may decrease with the decline of liver function.However,the contents of GLUT4 protein and mRNA in patients with advanced liver cirrhosis were similar to those of normal controls.In conclusion,insulin resistance is observed in patients with advanced liver cirrhosis but may not be correlated with the skeletal contents of GLUT4 protein and mRNA.

运动调节骨骼肌细胞葡萄糖摄取的研究进展

骨骼肌运动中葡萄糖摄取调节涉及复杂信号通路。研究显示,运动增强葡萄糖摄取并提升胰岛素敏感性,对预防胰岛素抵抗和糖尿病至关重要。文章概述了骨骼肌葡萄糖吸收过程及运动机制,重点分析了GLUT4蛋白的核心作用及AMPK、CaMK、ROS和NO等影响因素。考察体育活动对血糖摄入的效应,评估饮食和锻炼对胰岛素感受性的调整作用。这有助于深入理解生理机制,为治疗代谢性疾病提供理论支持。

坎离颗粒对血管紧张素II阻断骨骼肌细胞糖代谢PI3K/PKB/GLUT-4信号途径的影响及机制探讨

目的:探究坎离颗粒对小鼠骨骼肌成肌细胞(C2C12细胞)糖代谢的影响;探明坎离颗粒对血管紧张素Ⅱ阻断C2C12细胞糖代谢的影响是否通过PI3K/PKB/GLUT-4信号途径。方法:以C2C12细胞为研究对象,以胰岛素激活细胞糖代谢通路,以血管紧张素Ⅱ阻断被激活的通路,在此基础上设胰岛素组、模型对照组、坎离颗粒2、20、200μg/ml组,另设空白对照组。药物干预结束后,检测细胞中乳酸脱氢酶(LDH)及同工酶、乳酸、三磷酸腺苷(ATP)含量,葡萄糖运载体4(GLUT-4)、蛋白激酶B(PKB)、磷脂酰肌醇3激酶(PI3K)、丝裂原活化蛋白激酶p38(P38MAPK)蛋白及mRNA表达。结果:与空白组比较,胰岛素组对荧光标记2-脱氧葡萄糖(2-NBDG)摄取率显著升高;与胰岛素组比较,模型组对2-NBDG摄取率显著降低;与模型组比较,坎离颗粒三个剂量组对2-NBDG摄取率均显著升高。坎离颗粒2μg/ml组可明显降低乳酸水平。坎离颗粒20、200μg/ml组均可明显降低LDH4水平。与胰岛素组比较,模型组GLUT-4蛋白及mRNA、P-PKB、P-PI3K蛋白表达显著下调;与模型组比较,坎离颗粒可上调GLUT-4蛋白及mRNA、P-PKB、P-PI3K蛋白表达,以20、200μg/ml组最显著。结论:坎离颗粒可促进C2C12细胞糖摄取,改善糖代谢。并通过上调GLUT-4蛋白和mRNA表达、PKB、PI3K磷酸化蛋白表达,改善C2C12细胞的糖代谢,坎离颗粒对血管紧张素Ⅱ阻断骨骼肌细胞糖代谢的改善作用是通过PI3K/PKB/GLUT-4信号通路。

三黄汤对3T3-L1脂肪细胞糖脂代谢的影响

目的研究三黄汤(SHD)对胰岛素抵抗3T3-L1脂肪细胞糖脂代谢的作用及可能的调控机制。方法高糖高胰岛素(含地塞米松)诱导3T3-L1脂肪细胞发生胰岛素抵抗,给予对照药物罗格列酮(Ros)或不同浓度SHD干预24 h,检测培养上清中葡萄糖减少(消耗)量、甘油和游离脂肪酸(NEFA)浓度以及细胞内甘油三酯(TG)含量;以2-脱氧-[3H]-葡萄糖摄入法观察脂肪细胞对葡萄糖的转运率;应用反转录-聚合酶链反应(RT-PCR)检测葡萄糖转运体4(GLUT-4)的mRNA表达水平,以Western blot检测GLUT-4蛋白的表达水平。结果与对照组相比,SHD的中高剂量(5、10、20、40 g·L^(-1))能使胰岛素抵抗脂肪细胞的葡萄糖消耗量和葡萄糖的转运率增加(P<0.01)、脂肪细胞内TG降低(P<0.01),细胞上清液中甘油的浓度不同程度增加(P<0.01),并明显减少NEFA的溢出,以上变化在三黄汤5~20g·L^(-1)范围内呈现量效关系;同时,Ros增加葡萄糖消耗、葡萄糖的转运率和细胞内TG积累(P<0.01),对培养上清中甘油、NEFA无明显影响(P>0.05)。SHD中、高剂量与Ros都能不同程度明显上调GLUT-4的mRNA和蛋白表达水平(P<0.01)。结论 SHD能明显增加3T3-L1脂肪细胞的葡萄糖摄取和消耗,促进细胞内TG分解,并减少NEFA溢出,通过调节糖代谢和脂代谢改善胰岛素抵抗。

2-脱氧葡萄糖通过降低有氧糖酵解增强白血病K562/ADM耐药细胞对阿霉素的敏感性

目的研究2-脱氧葡萄糖(2-deoxy-D-glucose,2-DG)通过抑制糖代谢增强白血病K562/ADM多药耐药细胞对阿霉素(adriamycin,ADM)敏感性的作用及机制。方法以白血病K562/ADM及其亲本K562细胞为靶细胞模型,MTT法检测细胞增殖活性,葡萄糖、乳酸、己糖激酶测试盒分析葡萄糖消耗量、乳酸生成量和己糖激酶(hexokinase,HK)活性。Western blot法检测哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,m TOR)表达和磷酸化(p-m TOR)以及葡萄糖转运体-4(glucose transporter-4,GLUT-4)的表达。结果与亲本K562细胞相比,白血病K562/ADM耐药细胞HK活性、GLUT-4表达水平和有氧糖酵解能力增强。2-DG能够明显抑制K562/ADM及K562细胞的HK活性、葡萄糖消耗量和乳酸生成量,呈时间-浓度依赖性地抑制白血病细胞的增殖活性。低剂量2-DG和ADM可诱导K562/ADM细胞mT OR高表达及磷酸化水平增高,但2-DG与ADM联合则可有效对抗ADM诱导的K562/ADM细胞mT OR高表达和磷酸化,并可降低GLUT-4的表达,提高K562/ADM细胞对阿霉素的敏感性。结论 2-DG通过竞争性抑制HK活性和抵抗ADM诱发的代偿性mT OR活化,降低GLUT-4表达,有效阻断有氧糖酵解途径而降低K562/ADM耐药细胞的增殖活性、增强其对化疗药物的敏感性。

不同糖耐量人群血浆25-羟维生素D与葡萄糖转运子4及胆固醇调节元件结合蛋白1C表达关系的研究

目的探讨不同糖耐量人群血浆25-羟维生素D[25(OH)D]与葡萄糖转运子4(GluT-4)及胆固醇调节元件结合蛋白1C(SREBP-1C)表达的关系。方法随机分为T2DM组、IGR组及正常对照(NGT)组。检测血糖、血脂、HbA1 c等,电化学发光法测定25(OH)D和FIns。Western blot检测GluT-4及SREBP-1C蛋白的表达,RT-PCR检测GluT-4和SREBP-1C mRNA的表达。结果T2DM组、IGR组25(OH)D低于NGT组[(8.77±4.52)vs(18.35±5.90)vs(30.67±5.47)ng/ml,P<0.05],T2DM组低于IGR组(P<0.05)。T2DM组、IGR组血浆GluT-4 mRNA及蛋白表达低于NGT组[(0.235±0.412)vs(3.386±0.698)vs(6.325±0.959),(1.235±0.092)vs(2.430±0.153)vs(4.843±0.299),P<0.05],T2DM组较IGR组降低(P<0.05)。T2DM组、IGR组血浆中SREBP-1C mRNA及蛋白表达水平高于NGT组[(7.570±1.233)vs(5.561±0.820)vs(2.880±0.483),(8.340±1.092)vs(5.279±0.798)vs(2.340±0.135),P<0.05],T2DM组较IGR组升高(P<0.05)。Pearson相关性分析显示,25(OH)D与血浆中GluT-4 mRNA、蛋白表达呈正相关(P<0.05),与HbA_1 c、HOMA-IR、FIns、FPG、2 hPG、TG及SREBP-1C mRNA、SREBP-1C蛋白表达呈负相关(P<0.05)。血浆中GluT-4表达与SREBP-1C表达呈负相关(P<0.05)。结论血浆25(OH)D降低可引发糖耐量异常,甚至导致糖尿病,其机制可能与血浆中GluT-4表达降低及SREBP-1C表达升高有关。

代综方对3T3-L1脂肪细胞糖脂代谢的作用研究

目的研究代综方(DZF)对3T3-L1脂肪细胞糖脂代谢的作用及可能的调控机制。方法分化成熟的脂肪细胞给予不同浓度DZF或对照药物罗格列酮(Ros)干预48 h,检测培养上清中葡萄糖消耗量、甘油、游离脂肪酸(NEFA)浓度及胞内甘油三酯(TG)含量;应用反转录-聚合酶链反应(RT-PCR)检测葡萄糖转运体4(GLUT-4)、脂滴包被蛋白(perilipin)、激素敏感性脂肪酶(HSL)的mRNA表达。结果 DZF使培养上清中葡萄糖消耗量增加(P<0.01)、甘油的浓度不同程度增加,但对NEFA无显著影响(P>0.05),DZF使胞内TG降低(P<0.01);对照组Ros增加葡萄糖消耗(P<0.01),增加胞内TG积累(P<0.05),对培养上清中甘油、NEFA无显著影响(P>0.05);DZF各组能不同程度上调GLUT-4、HSL的mRNA表达,显著下调Perilipin的mRNA表达(P<0.01);Ros能上调GLUT-4、HSL、Perilipin的mRNA表达。结论 DZF能促进脂肪细胞葡萄糖消耗和胞内TG分解,改善脂质合成与分解的动态平衡,其作用机制与Ros增加胞内TG积累不同。