游泳运动对高脂饮食老年大鼠胰岛素抵抗和血清瘦素的影响

目的　研究单纯高脂饮食及不同强度运动对大鼠胰岛素敏感性和血清瘦素的影响。　方法　 4 8只 15月龄雄性SD大鼠随机分为对照组、高脂组、高脂加 90min运动组及高脂加 4 5min运动组 ,两运动组大鼠在高脂饮食同时均进行 15周不同强度的游泳运动。实验结束测定大鼠血糖、胰岛素、胆固醇 (TC)、甘油三酯 (TG)、高密度脂蛋白胆固醇 (HDL C)、低密度脂蛋白胆固醇 (LDL C)和瘦素 ,计算胰岛素敏感指数 (ISI)和肥胖评定 (Lee)指数。　结果　高脂组ISI〔 - (6 6 3± 0 39)〕较对照组〔 - (5 5 7± 0 31)〕明显低 (P <0 0 1) ;而运动组ISI分别为〔 - (5 5 2± 0 2 8)和 - (5 36±0 2 9)〕 ,均较高脂组明显升高 (均P <0 0 1)。两运动组间ISI差异无显著性 (P >0 0 5 )。运动后两组血清瘦素分别为 (2 2 3± 0 84 )ng/ml和 (3 0 2± 1 39)ng/ml,较高脂组 (7 94± 3 6 7)ng/ml明显下降 (P <0 0 1)。血清瘦素与胰岛素呈正相关 (r =0 2 82 ,P <0 0 5 ) ;与ISI负相关 (r =- 0 4 2 3,P <0 0 1)。　结论　单纯高脂饮食可致大鼠胰岛素抵抗 ,适当运动可增加高脂饮食大鼠的胰岛素敏感性 ;血清瘦素水平与胰岛素、胰岛素抵抗相关。     

高脂饮食大鼠脂肪组织甘油三酯脂酶的表达及罗格列酮的干预

目的 观察高脂饮食胰岛素抵抗大鼠脂肪组织中脂肪甘油三酯脂酶的表达及罗格列酮的干预效果.方法 5月龄雄性Wistar大鼠共40只随机分为正常对照组、高脂对照组和高脂+罗格列酮组,在清醒状态下行高胰岛素-正葡萄糖钳夹实验评价胰岛素敏感性,RT-PCR法和Western蛋白印迹技术检测脂肪组织中脂肪甘油三酯脂酶mRNA及蛋白表达.结果 (1)喂养4周末,高脂对照组的葡萄糖输注率低于正常对照组;8周末,高脂对照组甘油三酯、胆固醇、空腹血糖、空腹胰岛素、游离脂肪酸及内脏脂肪相对含量均明显升高,葡萄糖输注率降低;(2)罗格列酮干预后甘油三酯、胆固醇、血糖、胰岛素、游离脂肪酸和内脏脂肪相对含量降低,葡萄糖输注率升高;(3)与正常对照组相比,高脂对照组大鼠脂肪组织脂肪甘油三酯脂酶mRNA和蛋白的表达均减低,罗格列酮干预没有改变其表达;(4)ATGL蛋白的表达与胰岛素、游离脂肪酸负相关,与葡萄糖输注率呈正相关.结论 高脂喂养可引起胰岛素抵抗和脂肪组织脂肪甘油三酯脂酶的表达减低,这种变化在胰岛素抵抗早期可减少游离脂肪酸的释放.     

高脂饮食诱发大鼠胰岛素抵抗后肿瘤坏死因子—α的改变

目的 了解高脂饮食所致的大鼠胰岛素抵抗（ＩＲ）模型血及组织中肿瘤坏死因子－α（ＴＮＦ－α）含量的变化。方法 用脂肪占摄入热卡６１％的饮食饲养大鼠７周,以葡萄糖－胰岛试验（Ｇ－ＩｎｓＴＴ）筛选出ＩＲ大鼠,以放射免疫法分别检测其血甭、肝脏、红色股四头肌、脂肪匀浆中ＴＮＦ－α的含量。结果 是饮食致ＩＲ大鼠血及组织中ＴＮＦ－α含量均明显升高,且其升高程度与高脂岛素血症呈正相关,与Ｇ－ＩｎｓＴＴ中的Ｋ值呈负     

高脂饮食对C57L/J小鼠肝胆系统损伤的影响

目的观察C57L／J小鼠高脂饮食后，胆结石及脂肪肝形成情况，为这两种疾病的实验研究提供依据。方法雄性C57L／J小鼠24只，随机分为对照组、模型A组、模型B组。对照组给与正常饮食。模型组给与高脂饮食，通过红外光谱分析结石成分，全自动生化分析仪检测肝功、血脂，光镜检测肝脏脂肪变性。结果对照组无胆结石和胆固醇结晶出现，模型组则可见明显胆结石及胆固醇结晶，光镜下对照组肝脏无异常，模型组可见不同程度的肝脂肪变性，各模型组肝功、血脂明显高于对照组，有显著差异。结论通过给与高脂饮食成功造成C57L／J小鼠胆结石、脂肪肝模型，提示胆结石、脂肪肝具有相同的发病诱因。     

胰岛素对大鼠骨骼肌细胞脂联素受体基因表达的影响

目的了解体外胰岛素对原代培养大鼠骨骼肌细胞脂联素受体1表达的影响。方法体外原代培养骨骼肌细胞,应用SYBRGreenⅠ染料建立一种快速、可靠的实时定量PCR,对其主要要素进行优化。观察不同胰岛素浓度不同作用时间下,大鼠骨骼肌细胞脂联素受体基因表达水平的动态变化。结果建立敏感、特异、快速检测脂联素受体1mRNA的实时定量PCR方法,随着胰岛素浓度的增加,脂联素受体1表达逐渐降低。在较低浓度（胰岛素浓度〈1nmol/L）时,脂联素受体1表达的降低无统计学意义,当胰岛素浓度增加到10nmol/L及以上时,骨骼肌细胞脂联素受体1表达的降低有统计学意义（P〈0.05）,这种抑制作用1h后出现,24h后达到高峰。结论成功地建立SYBRGreenⅠ实时定量PCR检测脂联素受体基因的表达方法,体外高胰岛素对骨骼肌细胞脂联素受体1mRNA表达有抑制作用,并呈时间和剂量依赖性。     

差异显示PCR分析高脂饮食诱导的肥胖大鼠脂肪组织的基因表达谱

本实验采用高脂饮食饲养ＳＤ大鼠 ,建立肥胖大鼠模型 ,用差异显示ＰＣＲ(ＤＤ ＰＣＲ)方法比较高脂饲料组大鼠与普通饲料组大鼠脂肪组织中基因表达的差异 ,力求发现受饮食调控的基因 ,探讨高脂饮食致肥胖的分子机制。一、材料和方法1.动物模型与标本采集 :2 0只ＳＤ大鼠分为高脂饲料组和普通饲料组。动物饲养 16周。2 .脂肪组织总ＲＮＡ的抽提及处理 :(1)脂肪组织总ＲＮＡ的抽提 :取 1ｇ大网膜脂肪组织按照Ｔｒｉｚｏｌ总ＲＮＡ抽提试剂盒说明书进行。 (2 )总ＲＮＡ的处理 :用不含ＲＮＡ酶的ＤＮＡ酶处理抽提的总ＲＮＡ以去除含有的少量基因…     

长期温和的能量限制改善C57BL/6小鼠高脂喂养后的脂代谢紊乱

目的探讨温和的能量限制对小鼠脂代谢的影响。方法给予3周龄C57BL/6小鼠高脂饮食12周后,按随机数字表法分组,对照组不限制饮食,实验组小鼠喂食对照组小鼠摄食量的85%,喂养12周后,收集小鼠血浆并冻存肝脏。抽提肝脏脂质并用酶法检测脂质含量,油红O染色观察肝脏的脂质沉积;用实时定量聚合酶链反应法检测肝脏脂肪代谢相关基因的表达;并测定LDL、TG分泌速率和小鼠原代肝细胞脂肪酸氧化速率。结果实验组小鼠与对照组小鼠相比,在限食12周后:(1)体质量:(32.8±1.3)g比(38.9±3.5)g(P=0.007);(2)血浆TG水平:(0.26±0.01)mmol/L比(0.41±0.02)mmol/L(P=0.02),肝脏内TG含量:(435.7±26.3)μg/mg蛋白质比(812.4±38.2)μg/mg蛋白质(P=0.001);(3)实时定量聚合酶链反应结果显示,肝脏内长链脂肪酸和胆固醇合成相关基因mRNA表达水平无变化,但脂肪酸氧化基因mRNA表达水平显著增加(P=0.03)。肝脏原代细胞内脂肪酸的氧化速度增加了53.1%±7.2%(P=0.01),血浆游离脂肪酸水平:(0.41±0.04)mmol/L比(0.62±0.02)mmol/L(P=0.04);(4)肝脏中胆固醇:(85.2±9.8)μg/mg蛋白质比(169.3±13.5)μg/mg蛋白质(P=0.001),但血浆TC水平无显著改变。结论长期温和的能量限制可以有效缓解高脂饮食引起的小鼠肝脏的脂肪变性,这与肝脏中游离脂肪酸的氧化速度升高及摄取量降低密切相关;同时降低了小鼠血浆TG的水平,但没有改变血浆TC水平。     

高脂饮食对大鼠骨骼肌脂质中间代谢产物的影响及机制

目的观察高脂饮食对大鼠骨骼肌脂质中间代谢产物的沉积及脂肪酸代谢中CD36及CPT1的影响。方法雄性SD大鼠随机分为正常对照组、高脂饮食组,分别喂养12 w,分别测定大鼠血糖(BG)及胰岛素(INS)水平;透射电镜观察大鼠骨骼肌线粒体形态变化;GPO-PAP法检测骨骼肌甘油三酯(TG),ELISA试剂盒检测骨骼肌甘油二酯(DAG)、神经酰胺(CER)、长链脂酰辅酶A(LCCo As)的变化;用RT-PCR和Western印迹的方法分析大鼠骨骼肌CD36及CPT1的mRNA和蛋白的表达。结果与对照组相比,高脂组大鼠BG及INS水平均明显升高,GIR明显降低(P0.01);同时骨骼肌组织中TG、DAG、CER及LCCo As含量明显升高(P0.01)。与对照组相比高脂组骨骼肌细胞内可见大量大小不等的脂滴分布,线粒体肿胀,内外膜部分融合,线粒体嵴变少变短,部分或全部消失,甚至出现空泡化。与对照组相比,高脂组CD36的mRNA及蛋白的表达明显升高,CPT1的表达明显降低(P0.05)。结论高脂饮食可引起大鼠胰岛素抵抗及骨骼肌组织中脂质中间代谢产物的堆积,肌内脂质堆积与脂肪酸代谢中关键酶CD36、CPT1表达的变化有关。     

茵陈蒿汤化裁方对高脂饮食小鼠肝组织肝脂酶活性及mRNA转录的影响

目的 观察茵陈蒿汤化裁方对高脂饮食小鼠血脂调节作用及肝组织肝脂酶(HL)活性及其mRNA转录水平的影响.方法 高脂饮食饲养小鼠6 w,并设普食对照、模型对照、茵陈蒿汤化裁方高、低剂量组.药物干预4 w后,生化检测血清总胆固醇(TC)、甘油三酯(TG)含量,张蓉法测定肝组织匀浆HL活性,RT-PCR法检测HL mRNA转录水平.结果 茵陈蒿汤化裁方可显著降低血清TG水平(P＜0.01),提高肝组织匀浆HL活性(P＞0.01),而对肝组织HL mRNA的转录水平无明显影响(P>0.05).结论 增强肝组织HL活性是茵陈蒿汤化裁方调节脂质代谢的药理学机制之一,该方在高脂血症、脂肪肝及动脉粥样硬化等疾病的中医药防治领域具有潜在的应用价值.     

高脂诱导肥胖大鼠血清游离脂肪酸与血糖代谢的相关性

目的研究高脂诱导肥胖大鼠血清游离脂肪酸与血糖代谢的相关性。方法选择SD大鼠36只作为研究动物并随机分为高脂饮食组和普通饮食组,高脂饮食组给予高脂饲料喂养,正常饮食组给予普通饲料喂养,4 w、8 w、12 w后采集血清并测定游离脂肪酸(FFA)、空腹血糖(FPG)、空腹胰岛素(FINS),计算胰岛素抵抗指数(HOMA-IR)、胰岛素分泌指数(HOMA-β)。结果喂养8 w、12 w时,高脂饮食组大鼠体重明显高于普通饮食组(t=3.120,4.528,均P0.05);喂养4 w、8 w、12 w时,高脂饮食组大鼠血清中FFA均明显高于普通饮食组(t=5.995,8.175,13.942,均P0.05);两组FPG比较无统计学意义(t=0.869,0.496,0.827,均P0.05),高脂饮食组血清FINS、HOMA-IR、HOMA-β均明显高于普通饮食组(t=5.152,7.411,6.638;5.868,9.770,8.858;2.517,2.890,4.390,均P0.05);血清FFA含量与FINS、HOMA-IR、HOMA-β呈正相关(r=0.724,0.668,0.637,均P0.05)。结论高脂诱导肥胖大鼠的血清FFA含量显著升高且存在胰岛素抵抗和高胰岛素血症,FFA含量与胰岛素抵抗程度具有良好的相关性。     

Enhanced mitochondrial metabolism may account for the adaptation to insulin resistance in islets from C57BL/6J mice fed a high-fat diet

Aim/hypothesis Hyperinsulinaemia maintains euglycaemia in insulin-resistant states. The precise cellular mechanisms by which the beta cells adapt are still unresolved. A peripherally derived cue, such as increased circulating fatty acids, may instruct the beta cell to initiate an adaptive programme to maintain glucose homeostasis. When this fails, type 2 diabetes ensues. Because mitochondria play a key role in beta cell pathophysiology, we tested the hypothesis that mitochondrial metabolism is critical for beta cell adaptation to insulin resistance. Methods C57BL/6J mice were given high-fat (HF) diet for 12 weeks. We then analysed islet hormone secretion, metabolism in vivo and in vitro, and beta cell morphology. Results HF diet resulted in insulin resistance and glucose intolerance but not frank diabetes. Basal insulin secretion was elevated in isolated islets from HF mice with almost no additional response provoked by high glucose. In contrast, a strong secretory response was seen when islets from HF mice were stimulated with fuels that require mitochondrial metabolism, such as glutamate, glutamine, alpha-ketoisocaproic acid and succinate. Moreover, while glucose oxidation was impaired in islets from HF mice, oxidation of glutamine and palmitate was enhanced. Ultrastructural analysis of islets in HF mice revealed an accumulation of lipid droplets in beta cells and a twofold increase in mitochondrial area. Conclusions/interpretation We propose that beta cells exposed to increased lipid flux in insulin resistance respond by increasing mitochondrial volume. This expansion is associated with enhanced mitochondrial metabolism as a means of beta cell compensation. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible to authorised users.     

长期脂肪含量较高饲料喂养对大鼠胰岛素抵抗的影响

目的探讨脂肪含量较高饲料长期喂养对大鼠胰岛素抵抗的影响。方法大鼠随机分为两组,对照组以普通饲料喂养16 w,高脂组以脂肪热量比38.5%的饲料喂养12 w,再以脂肪热量比51.3%的饲料喂养4 w。实验结束时,测定空腹血糖(FBG)、空腹血浆胰岛素(FINS)并计算胰岛素敏感指数(ISI)和胰岛素抵抗指数(HOMA-IR);另外进行口服葡萄糖耐量试验(OGTT),计算血糖曲线下面积(AUC)。结果两组大鼠能量摄取相似,体重差别不大。高脂组大鼠FINS显著高于对照组(P<0.01),但FBG无显著差别。高脂组大鼠ISI显著下降(P<0.01),HOMA-IR显著上升(P<0.01),血糖AUC显著升高(P<0.01)。结论脂肪含量较高的饲料喂养大鼠16 w后引起了胰岛素抵抗和糖耐量异常。     

Glycogen synthase kinase 3 inhibition improves insulin-stimulated glucose metabolism but not hypertension in high-fat-fed C57BL/6J mice

Aims/hypothesis In the current study, the effect of a highly specific peptide inhibitor of glycogen synthase kinase 3 (GSK3) (L803-mts) on glucose metabolism and BP was examined in a high-fat (HF) fed mouse model of diabetes. Methods C57/BL6J mice were placed on an HF diet for 3 months and treated with L803-mts for 20 days, following which glucose metabolism was examined by euglycaemic–hyperinsulinaemic clamp studies. BP and heart rate were measured by radio-telemetry. Results The HF mice were obese, with impaired glucose tolerance and high plasma insulin and leptin levels. L803-mts treatment significantly reduced the insulin levels and doubled the glucose infusion rate required to maintain a euglycaemic condition in the HF+L803-mts group compared with the HF group. Insulin failed to suppress the endogenous glucose production rate in the HF group while decreasing it by 75% in the HF+L803-mts group, accompanied by increased liver glycogen synthase activity and net hepatic glycogen synthesis. GSK3 inhibition also reduced peripheral insulin resistance. Plasma glucose disappearance rate increased by 60% in the HF+L803-mts group compared with the HF group. In addition, glucose uptake in heart and gastrocnemius muscle was markedly improved. Although mean arterial pressure increased following the HF diet, it did not change significantly during the 12 days of L803-mts treatment. Conclusions/interpretation These studies demonstrate that GSK3 inhibition improved hepatic and peripheral insulin resistance in a mouse model of HF-induced diabetes, but it failed to have an effect on BP. GSK3 may represent an important therapeutic target for insulin resistance.     

Effects of pyridoxamine (K-163) on glucose intolerance and obesity in high-fat diet C57BL/6J mice

Advanced glycation end products (AGEs) contribute to the pathogenesis of diabetes-associated complications. Previously, we reported the possible effect of pyridoxamine (K-163), an AGE inhibitor, on improvement of glucose intolerance in type 2 diabetes mellitus KK-A^y/Ta mice. Recently, AGEs and oxidative stress have been shown to induce insulin resistance. The objective of the present study is to examine the effect of pyridoxamine on glucose intolerance and oxidative stress. C57BL/6J mice were divided into 3 groups as follows: low-fat diet, high-fat diet, and high-fat diet with pyridoxamine treatment. Body and adipose tissue weight, serum insulin, hydrogen peroxide, malondialdehyde and AGE, and urinary 8-hydroxy-2′-deoxyguanosine levels were measured. Nicotinamide adenine dinucleotide phosphate subunits, antioxidant enzymes, and adipocytokine messenger RNA expressions in the adipose tissues were evaluated. Akt/protein kinase B activity and glucose transporter 4 translocation in skeletal muscle were also evaluated. Body and adipose tissue weights of the pyridoxamine treatment group were significantly decreased compared with those of the high-fat diet group. Pyridoxamine attenuated serum hydrogen peroxide, malondialdehyde and AGE, and urinary 8-hydroxy-2′-deoxyguanosine and nicotinamide adenine dinucleotide phosphate oxidase expression; increased antioxidant enzyme expression; and improved dysregulation of adipocytokines in adipose tissues. Pyridoxamine improved blood glucose levels after glucose injection and fasting hyperinsulinemia. Suppressed Akt/protein kinase B activity and glucose transporter 4 translocation in skeletal muscle in high-fat diet mice were improved by pyridoxamine treatment. It appears that the antioxidative effect of pyridoxamine is associated with improvement of glucose intolerance and obesity in C57BL/6J mice fed a high-fat diet. We assume that pyridoxamine may be useful in the treatment of the obesity-associated metabolic syndrome.     

高脂饮食对老年大鼠骨骼肌脂肪酸含量及乙酰辅酶A羧化酶表达和活性的影响

目的 探讨增龄和高脂饮食对大鼠骨骼肌脂肪酸含量及乙酰辅酶A羧化酶(acetyl-coenzyme A carboxylase,ACC)表达和活性的影响.方法 将22～24月龄雄性Wistar大鼠随机分为老年对照组和高脂组;4～5月龄大鼠作为青年对照组.老年对照组和青年对照组给基础饲料,高脂组给予高脂饲料,喂养8周.用高胰岛素-正葡萄糖钳夹实验评价各组大鼠胰岛素敏感性,用全自动生化分析仪测定骨骼肌三酰甘油,用荧光分光光度计测定骨骼肌总的长链脂酰辅酶A含量,用Western-blot方法测定骨骼肌ACC、和磷酸化ACC(P-ACC)蛋白表达.结果 (1)老年对照组空腹血糖、胰岛索和游离脂肪酸高于青年对照组,高脂组上述几项指标进一步升高,并且出现血清三酰甘油和总胆固醇水平增高;(2)老年对照组葡萄糖输注率(glucose infusion rates,GIR)低于青年对照组,高脂组GIR低于老年对照组,高脂组GIR在8周末低于4周末;(3)老年对照组骨骼肌三酰甘油及长链脂酰辅酶A含量高于青年对照组,高脂组与老年对照组比较进一步升高;(4)老年对照组与青年对照组之间、高脂组与老年对照组之间骨骼肌ACC蛋白表达均无明显变化(P>0.05);骨骼肌P-ACC蛋白水平在老年对照组低于青年对照组,高脂组与老年对照组比较进一步降低(P<0.05或P<0.01).结论 与青年大鼠比较,老年大鼠更易出现脂肪酸代谢异常及胰岛素抵抗;高脂饮食导致老年大鼠骨骼肌脂质积聚更加严重,ACC活性的改变可能在骨骼肌脂质堆积和胰岛素抵抗发生中起了一定作用.     

Naltrexone effects on ethanol reward and discrimination in C57BL/6 mice

The effects of the opioid antagonist, naltrexone, on operant responding for oral ethanol reward delivered on a fixed-ratio schedule, and on the discriminative stimulus properties of intraperitoneally injected ethanol, was examined in two separate experiments. The ages, food/water motivational conditions, and naltrexone doses for the two experiments were similar to allow a direct comparison of naltrexone effects on the two measures. Male food-deprived C57BL/6 mice responded for ethanol during either preprandial (low thirst, high hunger motivation) or postprandial (high thirst, low hunger motivation tests). The reinforcing value of ethanol relative to water was greater during the preprandial tests; however, the amounts of ethanol consumed was greater during the postprandial tests, with some mice becoming unconscious during the 15-min test session. Naltrexone produced dose-responsive reductions in responding for ethanol under either testing condition. During postprandial tests, naltrexone reduced responding for ethanol reward at a dose (1.25 mg/kg) that had little effect on responding for water reward, suggesting some selectivity for ethanol reward. In addition, doses of naltrexone that reduced responding for ethanol rewards did not alter the discrimination of ethanol (g/kg) in an operant discrimination task, but did reduce the total number of responses made during these tests. Thus, under similar motivational and dosing conditions, the opiate antagonist attenuated the reinforcing, but not the discriminative properties of ethanol, suggesting that the latter is mediated by either different or additional neural mechanisms in C57BL/6 mice.     

C3H/HeJ mice carrying a toll-like receptor 4 mutation are protected against the development of insulin resistance in white adipose tissue in response to a high-fat diet

Aims/hypothesis Inflammation is associated with obesity and has been implicated in the development of diabetes and atherosclerosis. During gram-negative bacterial infection, lipopolysaccharide causes an inflammatory reaction via toll-like receptor 4 (TLR4), which has an essential function in the induction of innate and adaptative immunity. Our aim was to determine what role TLR4 plays in the development of metabolic phenotypes during high-fat feeding. Materials and methods We evaluated metabolic consequences of a high-fat diet in TLR4 mutant mice (C3H/HeJ) and their respective controls. Results TLR4 inactivation reduced food intake without significant modification of body weight, but with higher epididymal adipose tissue mass and adipocyte hypertrophy. It also attenuated the inflammatory response and increased glucose transport and the expression levels of adiponectin and lipogenic markers in white adipose tissue. In addition, TLR4 inactivation blunted insulin resistance induced by lipopolysaccharide in differentiated adipocytes. Increased feeding efficiency in TLR4 mutant mice was associated with lower mass and lower expression of uncoupling protein 1 gene in brown adipose tissue. Finally, TLR4 inactivation slowed the development of hepatic steatosis, reducing the liver triacylglycerol content and also expression levels of lipogenic and fibrosis markers. Conclusions/interpretation TLR4 influences white adipose tissue inflammation and insulin sensitivity, as well as liver fat storage, and is important in the regulation of metabolic phenotype during a fat-enriched diet. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.