2型糖尿病血浆抵抗素水平与胰岛素敏感性相关因素的研究

2型糖尿病患者血浆抵抗素水平明显高于正常人；在糖尿病患者中血浆抵抗素水平肥胖者明显高于非肥胖者，且与胰岛素敏感指数（ISI）呈负相关，与FPG、血脂、年龄、性别，WHR无相关性。     

对抵抗素在肥胖性胰岛素抵抗中作用及作用机制的争议

抵抗素是近年来发现的一种脂肪细胞分泌的多肽类信号分子,最初发现在肥胖小鼠中血清抵抗素水平上升,免疫中和血清抵抗素能改善胰岛素的敏感性,因此认为它可能是联系肥胖和胰岛素抵抗的关键因子。但是,后来有学者发现肥胖鼠白色脂肪组织中抵抗素mRNA水平下降,这与抵抗素主要来源于脂肪细胞相矛盾,而且大多数的人类实验都发现血清抵抗素水平上升与胰岛素抵抗并不相关。因此,目前对于抵抗素和胰岛素抵抗之间的关系尚存在很大争议。     

Human triglyceride-rich lipoproteins impair glucose metabolism and insulin signalling in L6 skeletal muscle cells independently of non-esterified fatty acid levels

AIMS/HYPOTHESIS: Elevated fasting and postprandial plasma levels of triglyceride-rich lipoproteins (TGRLs), i.e. VLDL/remnants and chylomicrons/remnants, are a characteristic feature of insulin resistance and are considered a consequence of this state. The aim of this study was to investigate whether intact TGRL particles are capable of inducing insulin resistance. METHODS: We studied the effect of highly purified TGRLs on glycogen synthesis, glycogen synthase activity, glucose uptake, insulin signalling and intramyocellular lipid (IMCL) content using fully differentiated L6 skeletal muscle cells. RESULTS: Incubation with TGRLs diminished insulin-stimulated glycogen synthesis, glycogen synthase activity, glucose uptake and insulin-stimulated phosphorylation of Akt and glycogen synthase kinase 3. Insulin-stimulated tyrosine phosphorylation of IRS-1, and IRS-1- and IRS-2-associated phosphatidylinositol 3-kinase (PI3K) activity were not impaired by TGRLs, suggesting that these steps were not involved in the lipoprotein-induced effects on glucose metabolism. The overall observed effects were time- and dose-dependent and paralleled IMCL accumulation. NEFA concentration in the incubation media did not increase in the presence of TGRLs indicating that the effects observed were solely due to intact lipoprotein particles. Moreover, co-incubation of TGRLs with orlistat, a potent active-site inhibitor of various lipases, did not alter TGRL-induced effects, whereas co-incubation with receptor-associated protein (RAP), which inhibits interaction of TGRL particles with members of the LDL receptor family, reversed the TGRL-induced effects on glycogen synthesis and insulin signalling. CONCLUSIONS/INTERPRETATION: Our data suggest that the accumulation of TGRLs in the blood stream of insulin-resistant patients may not only be a consequence of insulin resistance but could also be a cause for it.     

不同糖耐量状态下血清抵抗素和可溶性细胞间黏附分子质量浓度的变化

目的 探讨不同糖耐量状态下血清抵抗素(resistin)与可溶性细胞间黏附分子-1(sICAM-1)质量浓度的变化。 方法 2004-04～09在中国医科大学第一临床学院对52例2型糖尿病患者(DM组)、18例糖耐量异常(IGT)组及30例健康对照(NCT)组,采用酶联免疫分析法检测空腹血清resistin及sICAM-1质量浓度;同时检测空腹血糖、胰岛素及血脂水平;并以稳态模型计算胰岛素抵抗指数(HOMA-IR)。 结果 IGT组resistin明显高于DM组及NCT组(P均＜0.05);DM和IGT组sICAM-1均高于NCT组(P＜0.01,P＜0.05);DM组、IGT组HOMA-IR明显高于NCT组(P＜0.01)。 结论 res     

老年糖尿病患者血浆抵抗素与胰岛素抵抗关系的研究

目的　了解老年糖尿病患者血浆抵抗素的浓度及其与肥胖、胰岛素敏感性、血糖、血脂的关系。　方法　选择 5 1例老年 2型糖尿病患者和 4 2例健康老年人 ,分别分为肥胖组和非肥胖组 ,用竞争性酶联免疫吸附法测定各组空腹血浆抵抗素水平 ,同时检测空腹血糖、空腹胰岛素、血脂、胰岛素敏感指数 ,测量受试对象腰围、臀围、腰臀比。　结果　在对照组和糖尿病组中 ,肥胖组空腹血浆抵抗素水平显著高于非肥胖组 (P <0 0 5 ) ;糖尿病非肥胖组空腹血浆抵抗素水平显著高于对照非肥胖组 (P <0 0 1) ,但与对照肥胖组比较 ,差异无显著性 ;糖尿病肥胖组空腹血浆抵抗素水平显著高于对照肥胖组 (P <0 0 5 )。抵抗素与体质指数呈正相关关系 (r =0 2 5 ,P <0 0 5 ) ,与胰岛素敏感指数及空腹胰岛素呈负相关关系 (r=- 0 32、- 0 35 ,P <0 0 5 )。而抵抗素与空腹血糖、各项血脂指标、年龄、性别及腰臀比之间无明显相关性。　结论　在肥胖发展为糖尿病的过程中 ,抵抗素可能参与了胰岛素抵抗 ,并有可能成为诊断胰岛素抵抗的指标之一。     

不同糖耐量人群血浆神经肽B、抵抗素与糖脂代谢的关系

在不同糖耐量人群测定血浆神经肽B和抵抗素水平。结果显示2型糖尿病患者空腹神经肽B水平明显高于对照组,而其空腹和糖负荷后2 h抵抗素水平明显低于对照组,空腹神经肽B水平与血糖、腰臀比和胆固醇呈正相关。提示神经肽B与代谢紊乱有一定关联。     

皮下脂肪和胎盘的抵抗素表达及与胰岛素抵抗的关系

目的探讨抵抗素与胰岛素抵抗(IR)、肥胖和糖尿病的关系。方法于2003-032004-12选取武汉协和医院正常人腹部(n=12)、腿部(n=8)、妊娠妇女腹部(n=12)皮下脂肪组织和胎盘(n=12)为标本,以Western blot法检测抵抗素蛋白表达情况,测定血糖、血脂、胰岛素、体重、身高,计算IR指数、体重指数(BMI)、体内脂肪百分比(BF%)。结果妊娠妇女胎盘组抵抗素蛋白(67905±8441)(OD值)的表达明显高于妊娠腹部组(40718±3818)(P<0·01);正常人腹部组(39421±6087)(P<0·01)、腿部组皮下脂肪组织(14942±6706)(P<0·001);妊娠腹部组和正常人腹部组皮下脂肪组织均明显高于腿部组(P<0·001);抵抗素蛋白与BMI、IR指数、BF、空腹血糖呈正相关性。结论胎盘可分泌抵抗素,抵抗素与中心性肥胖有密切关系,可能引起IR,导致肥胖、2型糖尿病和妊娠糖尿病。     

高脂喂养和脂质诱导的胰岛素抵抗大鼠糖代谢、抵抗素和脂联素的变化

目的探讨高脂喂养和脂质灌注诱导的胰岛素抵抗（IR）大鼠糖代谢、血浆抵抗素、脂联素水平和肌肉抵抗素蛋白表达的变化。方法分别采用高脂喂养和脂质灌注制造IR大鼠模型,用扩展胰岛素钳夹术评价胰岛素敏感性和糖代谢的变化,用酶联免疫法和斑点印迹法测定血浆脂联素及肌肉抵抗素水平。结果高脂喂养组（HF）大鼠基础血浆FFA水平明显高于对照组（NC）（P〈0.05）。钳夹稳态时,NC组和HF组FFA分别被抑制77%和56%,而脂质灌注组（L）FFA水平明显升高。HF和L组糖输注率明显低于NC组（P均〈0.01）,而L组又明显低于HF组（P〈0.05）;L组糖清除率也明显低于NC组（P〈0.01）。NC组肝糖输出率被抑制达85%,而HF和L组分别被抑制29%和9%。钳夹结束时,L组血浆抵抗素水平较基础值明显升高（P〈0.01）,且L组肌肉抵抗素水平明显高于NC组和HF组（P均〈0.05）。钳夹后各组脂联素水平均明显降低（P〈0.05）。结论脂质灌注和高脂喂养诱导了机体外周和肝组织的IR,但以前者更为明显,可能与抵抗素增加有关。     

Effects of resistin expression on glucose metabolism and hepatic insulin resistance

In order to observe the effect of increased serum resistin on glucose metabolism, insulin sensitivity, and hepatic insulin resistance (IR), mice were intravenously injected with recombinant adenovirus carrying the resistin gene (Adv-resistin-EGFP). Changes in hepatic glucose metabolism were observed using the Periodic Acid-Schiff method. Hepatic AMP-activated protein kinase (AMPK) activation was assessed by Western blot analysis, and glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression was determined using real-time RT-PCR. Although no effect on fasting blood glucose was detected, increased fasting insulin levels, decreased glucose tolerance and insulin sensitivity, and reduced hepatic glycogen levels and AMPK activation were seen in the Adv-resistin-EGFP mice. Finally, elevated G6Pase and PEPCK mRNA expression levels were detected upon overexpression of resistin. Resistin may inhibit hepatic AMPK activity, which results in elevated expression of gluconeogenic enzymes thereby affecting glucose metabolism and leading to decreased glycogen storage that contributes to the development of hepatic IR.     

非酒精性脂肪肝血浆抵抗素与肥胖和胰岛素抵抗关系的研究

目的探讨非酒精性脂肪肝(NAFLD)血浆抵抗素与肥胖和胰岛素抵抗的关系。方法对兰州大学第一医院2005年10月至2006年2月60例NAFLD患者和28名年龄、性别相匹配的正常对照者,采用ELISA方法测定空腹血浆抵抗素,同时检测其身高、体重、腰围、臀围、血压、血糖、血脂、肝功能及胰岛素水平,并计算体重指数、脂肪百分比、腰臀比和胰岛素抵抗指数。结果NAFLD组与正常对照组相比,其血浆抵抗素明显升高[(8.56±2.5)ng/mL对(6.39±2.81)ng/mL,P<0.01]。相关分析显示血浆抵抗素与空腹胰岛素、胰岛素抵抗指数呈显著正相关(分别为r=0.271,P=0.036;r=0.30,P=0.020);而与腰臀比、体重指数、脂肪百分比、收缩压、舒张压、总胆固醇、甘油三酯、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇、血糖无相关性(P>0.05)。结论NAFLD患者血浆抵抗素明显升高,与胰岛素抵抗程度呈显著正相关,与肥胖无相关性。因而抵抗素可能主要与肝源性胰岛素抵抗有关,而与肥胖相关的胰岛素抵抗无关。     

不同糖耐量人群血清抵抗素水平及其相关因素分析

酶免法测定50例2型糖尿病（DM组）、50例糖耐量减低（IGT组）及40例糖耐量正常（NGT组）个体的空腹血清抵抗素水平，结果显示IGT组和DM组显著高于NGT组（P〈0．05，P〈0．01）；回归分析显示FPG和FIns与抵抗素的关系较为密切。     

A paradox： Insulin inhibits expression and secretion of resistin which induces insulin resistance

AIM： To confirm whether insulin regulates resistin expression and secretion during differentiation of 3T3-L1 preadipocytes and the relationship of resistin with insulin resistance both in vivo and in vitro. METHODS： Supernatant resistin was measured during differentiation of 3T3-L1 preadipocytes. L6 rat myoblasts and hepatoma cell line H4IIE were used to confirm the cellular function of resistin. Diet-induced obese rats were used as an insulin resistance model to study the relationship of resistin with insulin resistance. RESULTS： Resistin expression and secretion were enhanced during differentiation 3T3-L1 preadipocytes. This cellular differentiation stimulated resistin expression and secretion, but was suppressed by insulin. Resistin also induced insulin resistance in H4IIE hepatocytes and L6 myoblasts. In diet-induced obese rats, serum resistin levels were negatively correlated with insulin sensitivity, but not with serum insulin. CONCLUSION： Insulin can inhibit resistin expression and secretion in vitro, but insulin is not a major regulator of resistin in vivo. Fat tissue mass affects insulin sensitivity by altering the expression and secretion of resistin.     

不同糖耐量状态的原发性高血压患者血清抵抗素水平

目的　了解不同糖耐量状态原发性高血压患者血清抵抗素浓度 ,探讨肥胖与糖尿病(DM)的关系。方法　酶免疫测定法检测 71例原发性高血压患者〔2型DM 18例 ,糖耐量低减 (IGT)2 6例 ,正常糖耐量 (NGT) 2 7例 ;男 33例 ,女 38例〕的空腹血清抵抗素水平 ,口服葡萄糖耐量试验和胰岛素释放试验 ,测定血浆葡萄糖浓度和血清胰岛素浓度 ,计算葡萄糖曲线下面积 (AUCG) ,根据Cederholm公式计算胰岛素敏感指数 (ISI) ;测量收缩压 (SBP)、舒张压 (DBP)、身高、体重、腰围、臀围 ,计算体重指数 (BMI)、体内脂肪百分比 (BF % )及腰围 /臀围比 (WHR)。结果　空腹血清抵抗素浓度(μg/L) :DM组 (2 9.8± 12 .1)显著高于NGT组 (2 2 .0± 8.4 ) (P <0 .0 5 ) ,略高于IGT组 (2 5 .1± 10 .4 )(P >0 .0 5 )。空腹血清抵抗素浓度与AUCG(r =0 .38,P <0 .0 0 1)及BF % (r=0 .35 ,P <0 .0 1)呈显著正相关 ,与ISI呈显著负相关 (r =- 0 .2 4 ,P <0 .0 5 ) ,与SBP、DBP、BMI及WHR无相关。结论　 2型DM患者空腹血清抵抗素水平升高 ,血清抵抗素浓度与血糖浓度及BF %的相关性提示人体抵抗素可能是肥胖与糖尿病连系所在     

Peripheral glucose uptake and skeletal muscle GLUT4 content in man: effect of insulin and free fatty acids.

To investigate the relationship between glucose uptake and the content of the insulin regulatable glucose transporter, GLUT4, in skeletal muscle at near physiological insulin concentrations in vivo, we measured the effect of a 3h euglycemic insulin-infusion (40 mU m-2 min-1) on glucose uptake and skeletal muscle GLUT4 content in 10 healthy subjects. We found no correlation (r approximately 0.1) between individual muscle GLUT4 content and insulin-stimulated glucose uptake. Mean GLUT4 content in skeletal muscle was reduced by 19 +/- 6.3% (mean +/- SE, p less than 0.02) after insulin infusion. However, when the same subjects were made insulin resistant by infusion of lipid, as evidenced by a reduction of 16 +/- 7.2% (mean +/- SE, p less than 0.05), in insulin-stimulated glucose uptake, the effect of insulin on GLUT4 content was attenuated and no change in GLUT4 content was observed. Our results show that the total content of skeletal muscle GLUT4 is a poor predictor for in vivo response to near physiological insulin concentrations in healthy human subjects.     

胰岛素治疗对血浆抵抗素水平的影响

经ELISA方法测得的空腹血浆抵抗素水平，2型糖尿病患者显著高于正常对照组（P〈0．05）；而在有和无糖尿病微血管病患者之间，不存在明显差异（P〉0．05）。经胰岛素治疗，血抵抗素水平明显下降。     

肥胖患者脂肪组织抵抗素基因mRNA表达的研究

19例肥胖者与20例体重正常者的网膜脂肪与皮下脂肪的研究显示，抵抗素基因表达量，肥胖者与体重正常者无差异，网膜脂肪与皮下脂肪无差异。这提示，抵抗素基因表达与胰岛素抵抗无关。     

胰岛素调节骨骼肌细胞葡萄糖转运子4内在活性的研究

目的探讨胰岛素刺激骨骼肌摄取葡萄糖的机制。方法观察GluT4转位和葡萄糖摄取对SB203580和Wortmannin的响应,以及胰岛素在分化前后的细胞中对两者的作用,研究胰岛素信号通路。结果胰岛素分别增加GluT4转位和葡萄糖摄取2.5±0.2倍和2.2±0.1倍;但t1/2不同,分别为3.3min和6.0min;且两者对Wortmannin的敏感性不同,IC50分别为43nmol/L和3nmol/L。SB203580分别抑制64%和62%胰岛素刺激的葡萄糖摄取和细胞膜上GluT4的标记,但不影响GluT4转位;胰岛素刺激前骨骼肌细胞葡萄糖摄取增加的倍数(1.7±0.1倍vs对照组)小于GluT4转位增加的倍数(2.3±0.1倍vs对照组)。结论成熟骨骼肌细胞中存在两个胰岛素信号转导途径,分别介导GluT4的转位和活化,胰岛素利用这两条信号通路达到最大的刺激细胞摄取葡萄糖的作用。     

The kinetics of glucose uptake by isolated fat cells and the influence of insulin

Summary From measurements of glucose uptake by rat adipocytes, values of K (half-saturation constant) and V (maximal uptake at saturating glucose concentrations) are calculated. Insulin increases glucose uptake. Mannose and 3-O-methylglucose inhibit uptake. Different cell preparations give different values for K, V and insulin sensitivity. The possible effect on these differing parameters of adipocyte triglyceride content is considered. However the non-linearity of some double-reciprocal plots and certain correlations between the various kinetic parameters lead to the suggestion that rat adipocytes may have two systems for glucose uptake.

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Zusammenfassung Aus Bestimmungen der Glukoseaufnahme durch die Adipozyten von Ratten wurden die Werte für K (Halbsättigungskonstante) und V (maximale Aufnahme bei Glukosesaturation) errechnet. Insulin erhöht die Glukoseaufnahme, Mannose und 3-O-Methylglukose beschränken sie. Verschiedene Zellpräparate ergeben unterschiedliche Werte für K, V und Insulinempfindlichkeit. Die mögliche Auswirkung des Triglyceridgehaltes der Adipozyten auf die einzelnen Parameter wird besprochen. Die Tatsache dass manche der von den doppelt-reziproken Werten erhaltenen Kurven nicht linear sind und gewisse Korrelationen der kinetischen Parameter sprechen dafür, dass Rattenadipozyten möglicherweise zwei Systeme für Glukoseaufnahme haben.

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Resumen Se calculan los valores de K (constante de semisaturación) y de V (captación máxima y concentraciones de glucosa saturantes), por medio de mediciones de la captación de glucosa por parte de adipocitos de rata. La insulina aumenta la captación de glucosa, mientras que la manosa y el 3-O-metilglucosa la inhiben. Preparados celulares diversos facilitan diferentes valores por lo que se refiere a K, V y la sensibilidad a la insulina. Se considera el posible efecto del contenido de triglicéridos de los adipocitos según esos diversos parámetros. Sin embargo, la falta de linealidad de algunos diagrams en los que las variables se han transformado en sus recíprocos y ciertas correlaciones entre los varios parámetros cinéticos dan lugar a que se pueda suponer que en los adipocitos de rata puedan existir dos sistemas de captación de la glucosa.

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Résumé Après avoir mesuré le captage de glucose par les adipocytes de rat, on calcule les valeurs de K (constante de semi-saturation) et de V (captage maximum à des concentrations de glucose saturantes). L'insuline accroît le captage de glucose, tandis que le mannose et le 3-O-méthylglucose l'interdisent. Plusieurs préparations cellulaires donnent des valeurs différentes en ce qui concerne K, V et la sensibilité à l'insuline. On prend en considération l'effet possible de la teneur en triglycérides des adipocytes sur ces différents paramètres. Cependant, le caractère non-linéaire de certains diagrammes où les deux variables sont transformées dans leurs valéurs réciproques et certaines corrélations entre les divers paramètres cinétiques laissent penser à deux systèmes de captage de glucose dans les adipocytes de rat.

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Riassunto Da misurazioni della captazione di glucosio da parte di adipociti di ratto vengono calcolati i valori di K (costante di semi-saturazione) e di V (captazione massima a concentrazioni di glucosio saturanti). L'insulina aumenta la captazione di glucosio, mentre il mannosio ed il 3-O-metilglucosio la inibiscono. Preparati cellulari diversi forniscono differenti valori per quanto riguarda K, V e la sensibilità all'insulina. Viene considerato il possibile effetto del contenuto in trigliceridi degli adipociti su questi diversi parametri. Tuttavia, la non linearità di alcuni diagrammi in cui entrambe le variabili sono trasformate nei loro reciproci e certe correlazioni tra i varî parametri cinetici fanno pensare che negli adipociti di ratto possano esserci due sistemi di captazione del glucosio.

     

Globular adiponectin increases GLUT4 translocation and glucose uptake but reduces glycogen synthesis in rat skeletal muscle cells

Aims/hypothesis The aim of this study was to determine whether adiponectin elicits glucose uptake via increased GLUT4 translocation and to investigate the metabolic fate of glucose in skeletal muscle cells treated with globular adiponectin.Materials and methods Basal and insulin-stimulated 2-deoxy-d-[³H]glucose uptake, cell surface myc-tagged GLUT4 content, production of ¹⁴CO₂ by oxidation of d-[U-¹⁴C]glucose and [1-¹⁴C]oleate, and incorporation of d-[U-¹⁴C]glucose into glycogen and lactate were measured in the presence and absence of globular adiponectin.Results RT-PCR and Western blot analysis revealed that L6 cells and rat skeletal muscle cells express AdipoR1 mRNA and protein. Globular adiponectin increased both GLUT4 translocation and glucose uptake by increasing the transport V_max of glucose without altering the K_m. Interestingly, the incorporation of d-[U-¹⁴C]glucose into glycogen under basal and insulin-stimulated conditions was significantly decreased by globular adiponectin, whereas lactate production was increased. Furthermore, globular adiponectin did not affect glucose oxidation, but enhanced phosphorylation of AMP kinase and acetyl-CoA carboxylase, and fatty acid oxidation.Conclusions/interpretation The present study is the first to show that globular adiponectin increases glucose uptake in skeletal muscle cells via GLUT4 translocation and subsequently reduces the rate of glycogen synthesis and shifts glucose metabolism toward lactate production. These effects are consistent with the increased phosphorylation of AMP kinase and acetyl-CoA carboxylase and oxidation of fatty acids induced by globular adiponectin.     

Partial rescue of in vivo insulin signalling in skeletal muscle by impaired insulin clearance in heterozygous carriers of a mutation in the insulin receptor gene

Aims/hypothesis Recently we reported the coexistence of postprandial hypoglycaemia and moderate insulin resistance in heterozygous carriers of the Arg1174Gln mutation in the insulin receptor gene (INSR). Controlled studies of in vivo insulin signalling in humans with mutant INSR are unavailable, and therefore the cellular mechanisms underlying insulin resistance in Arg1174Gln carriers remain to be clarified.Subjects, materials and methods We studied glucose metabolism and insulin signalling in skeletal muscle from six Arg1174Gln carriers and matched control subjects during a euglycaemic–hyperinsulinaemic clamp.Results Impaired clearance of exogenous insulin caused four-fold higher clamp insulin levels in Arg1174Gln carriers compared with control subjects (p<0.05). In Arg1174Gln carriers insulin increased glucose disposal and non-oxidative glucose metabolism (p<0.05), but to a lower extent than in controls (p<0.05). Insulin increased Akt phosphorylation at Ser473 and Thr308, inhibited glycogen synthase kinase-3α activity, reduced phosphorylation of glycogen synthase at sites 3a+3b, and increased glycogen synthase activity in Arg1174Gln carriers (all p<0.05). In the insulin-stimulated state, Akt phosphorylation at Thr308 and glycogen synthase activity were reduced in Arg1174Gln carriers compared with controls (p<0.05), whereas glycogen synthase kinase-3α activity and phosphorylation of glycogen synthase at sites 3a+3b were similar in the two groups.Conclusions/interpretation In vivo insulin signalling in skeletal muscle of patients harbouring the Arg1174Gln mutation is surprisingly intact, with modest impairments in insulin-stimulated activity of Akt and glycogen synthase explaining the moderate degree of insulin resistance. Our data suggest that impaired insulin clearance in part rescues in vivo insulin signalling in muscle in these carriers of a mutant INSR, probably by increasing insulin action on the non-mutated insulin receptors.