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。     

核因子κB在胰岛素抵抗大鼠动脉内皮细胞的表达及意义

目的观察胰岛素抵抗（IR）大鼠血清脂联素及动脉内皮细胞内核因子κB（NF-κB）的变化。方法4周龄雄性W istar大鼠30只,随机分成对照组、高脂组、高脂高糖组,喂养8 w后,用高胰岛素-正血糖钳夹技术评估IR程度,酶联免疫吸附测定大鼠血清脂联素,免疫组化的方法测定动脉内皮细胞内NF-κB。结果高脂组、高脂高糖组产生IR,高脂高糖组较高脂组明显;血清脂联素对照组高于高脂组及高脂高糖组（P〈0.01）,高脂组又高于高脂高糖组（P〈0.05）;动脉内皮细胞NF-κB在高脂组和高脂高糖组动脉内皮细胞的表达明显高于对照组。结论高脂饮食可诱导大鼠产生IR,IR大鼠血清脂联素降低,NF-κB在动脉内皮细胞的表达升高。     

高脂饲养诱导大鼠胰岛素抵抗的动态观察

目的观察高脂饲养诱导大鼠胰岛素抵抗（IR）过程中血液生化指标和IR程度的动态变化。方法雄性Sprague-Dawley（SD）大鼠30只。随机分为高脂组和对照组。对照组喂养标准饲料，高脂组喂养高脂饲料，脂类以猪油为主，热量比占59．8％。高脂喂养2、4、6和8w，分别用口服糖耐量（OGTT），胰岛素敏感指数（ISI）和正常葡萄糖-高胰岛素血糖钳夹等方法检测IR；用快速血糖测定仪检测血糖，用氧化酶法测定血中甘油三酯（TG）和胆固醇（TC）浓度，并分析TG和TC浓度与ISI的相关性。结果高脂饲料喂养4w，检测到IR产生，随着喂养时间延长，IR程度增大。比较两组OGTT，各时间点血糖出现差异的顺序是30和60、120、0min。两组大鼠血中脂肪酸浓度在4w开始出现差异（P〈0．05），TC在6w开始出现差异（P〈0．01），TG和TC浓度在8W时与IS1具有相关性（P〈0．01）。结论高脂饲料成功诱导出IR，高脂组与对照组从4w末开始具有明显不同的代谢特征。     

瑞舒伐他汀类、替米沙坦对胰岛素抵抗大鼠肝脏的IKK、ROS表达的影响

目的测定不同饮食喂养大鼠和瑞舒伐他汀及替米沙坦干预后大鼠产生胰岛素抵抗(IR)的情况,观察大鼠肝脏中IKK、活性氧(ROS)表达的变化。方法 4周龄Wistar雄性大鼠40只,以高糖高脂饮食诱导建立IR模型,以高脂给药(ARB类、他汀类)诱导建立实验组,通过RT-PCR方法检测IR大鼠肝脏组织中IKK、ROS的表达水平。结果高糖高脂饲料组大鼠产生IR,给予瑞舒伐他汀干预后IR明显改善,高糖高脂饲料组大鼠ROS、IKK在肝脏中的表达明显高于对照组大鼠,瑞舒伐他汀药物可降低IR组大鼠ROS、IKK在肝脏中的表达。结论高脂高糖饲料喂养8 w可诱导大鼠产生IR。IR大鼠体内氧化应激增强ROS产生增加。过量的ROS通过激活IKK等通路,干扰细胞胰岛素受体信号转导,导致IR。通过瑞舒伐他汀、替米沙坦干预,可使ROS、IKK等表达水平下调,明显改善IR,其中瑞舒伐他汀降低更为明显。     

胰岛素抵抗小鼠骨骼肌中磷脂酰肌醇3激酶表达及肌糖原含量的改变

目的：研究高脂饮食喂养诱导的胰岛素抵抗（IR）小鼠骨骼肌中磷脂酰肌醇3激酶（PI3K）表达及肌糖原含量的改变。方法将20只雄性 KM小鼠随机分为对照组（NC 组,10只）和 IR 组（10只）,NC 组予常规饲料,IR 组予高脂饲料。16周时 IR 造模成功,记录小鼠体质量、空腹血糖（FBG）和空腹胰岛素（FINS）,并计算稳态模型胰岛素抵抗指数（HOMA-IR）;Western blot 法检测骨骼肌 PI3K 的表达,过碘酸雪夫（PAS）染色观察骨骼肌糖原含量的变化。结果与 NC 组比较,IR 组小鼠体质量、FBG、FINS 及 HOMA-IR 增高（P 均＜0．05）,IR 组骨骼肌中 PI3K 的表达显著降低（P ＜0．05）;PAS 染色显示 NC 组骨骼肌细胞内紫红色着色广泛,着色颗粒较多,IR 组着色浅,着色颗粒较少。结论骨骼肌 PI3K 表达降低可能是导致肌肉 IR 产生的原因之一。     

高脂喂养的胰岛素抵抗大鼠骨骼肌蛋白激酶B mRNA表达的改变

目的研究高脂饮食喂养的胰岛素抵抗(IR)大鼠胰岛素敏感性及骨骼肌中蛋白激酶B(PKB)mRNA表达改变。方法 70只大鼠随机分为正常对照组和高脂饮食组,高脂饮食组采用高脂喂养的方法建立IR大鼠模型,用高胰岛素-正常葡萄糖钳夹实验测定葡萄糖输注率(GIR),同时测定各组大鼠空腹血糖(FPG)、空腹胰岛素(FINS)等指标的水平,实时荧光定量RT-PCR测定大鼠骨骼肌PKB mRNA表达。结果①高脂喂养4 w后,高脂组FPG、FINS、胰岛素抵抗指数(HOMA-IR)均较正常对照组显著升高,而胰岛素敏感指数(ISI)下降(P<0.05),GIR显著低于正常对照组(P<0.01),说明高脂组存在IR,IR模型制造成功。②与正常对照组相比高脂组PKB mRNA表达明显减弱(P<0.05)。结论高脂饮食喂养的IR大鼠IR的产生与骨骼肌胰岛素刺激PKB表达明显降低有关。     

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。     

mTOR／S6K1信号通路在高脂饮食诱导小鼠胰岛素抵抗发生中的作用

目的探讨mTOR及其下游效应因子S6K1在胰岛素抵抗（IR）发生中的作用。方法C57BL／6雄性小鼠20只随机平均分为正常饮食组（NC组）和高脂饮食组（HF组）。后者喂养14周后建立IR模型。检测两组血清胰岛素水平和葡萄糖耐量,显微镜下观察胰岛形态学变化;检测骨骼肌中mTOR和S6K1mRNA的表达,以及mTOR、S6K1和其磷酸化水平蛋白的表达。结果与NC组相比,HF组小鼠表现出明显的IR症状,其体重和空腹胰岛素分别升高了21．99％（P〈0．05）和181．82％（P〈0．01）;胰岛8细胞团面积也显著增加,糖耐量明显受损,骨骼肌细胞中mTOR mRNA和蛋白分别升高了25．61％（P〈0．05）和37．41％（P〈0．01）,S6K1 mRNA和蛋白分别升高了54．98％（P〈0．01）和37．36％（P〈0．01）,S6K1磷酸化水平蛋白表达在高脂饮食后升高了680．15％（P〈0．01）。结论mTOR／S6K1信号通路与高脂饮食诱导IR的发生密切相关。     

替米沙坦、瑞舒伐他汀对胰岛素抵抗大鼠骨骼肌小窝蛋白1、葡萄糖转运蛋白4表达的影响

目的测定不同饮食喂养大鼠和替米沙坦、瑞舒伐他汀干预后大鼠产生胰岛素抵抗(IR)的情况,观察大鼠骨骼肌中小窝蛋白(Caveolin)1、葡萄糖转运蛋白(GLUT)4表达的变化。方法 4周龄Wistar雄性大鼠48只,以高糖高脂饮食诱导建立IR模型,以高糖高脂给药(替米沙坦、瑞舒伐他汀)诱导建立实验组,通过RT-PCR方法检测IR大鼠骨骼肌组织中Caveolin 1、GLUT4的表达水平。结果高糖高脂喂养组产生IR,给予替米沙坦、瑞舒伐他汀干预后IR明显改善,高糖高脂组Caveolin1 mRNA在骨骼肌中的表达明显高于对照组(P<0.05),高糖高脂组GLUT4 mR-NA在骨骼肌中的表达明显低于对照组(P<0.05),替米沙坦、瑞舒伐他汀可降低Caveolin1 mRNA在IR大鼠骨骼肌中的表达,升高GLUT4 mRNA在IR大鼠骨骼肌中的表达。结论①高糖高脂饲料喂养8 w可诱导大鼠IR。②IR大鼠骨骼肌组织Caveolin 1表达增加,GLUT4表达减少。③通过替米沙坦类、他汀类药物干预,可改善IR,降低Caveolin1表达水平,升高GLUT4表达水平。     

罗格列酮对老年胰岛素抵抗大鼠肝脏脂肪酸代谢及胰岛素敏感性的影响

目的 研究罗格列酮对老年胰岛素抵抗(insulin resistance,IR)大鼠肝脏脂肪酸代谢及胰岛素敏感性的影响.方法 22～24月龄雄性Wistar大鼠随机分为老年对照组(OC组)和高脂喂养组.OC组喂饲基础饲料,高脂喂养组喂饲高脂饲料.喂养至第4周末行高胰岛素-正葡萄糖钳夹实验评价高脂喂养组IR状态.判断造模成功后将高脂喂养组随机分为高脂(HF)组和罗格列酮干预(RSG)组.两组除继续喂以高脂饲料外,RSG组予罗格列酮3 mg·kg-1·d-1灌胃,HF组予等体积生理盐水灌胃,继续喂养4 w.实验第8周末,再次行钳夹实验评价各组大鼠胰岛素敏感性;肝脏甘油三酯经氯仿/甲醇抽提后用全自动生化分析仪测定.结果 分组喂养4时,钳夹实验发现高脂喂养组葡萄糖输注率(glucose infusion rates,GIR)低于OC组(P＜0.05),说明高脂喂养组IR模型诱导成功.继续喂养4 w后,HF组GIR进一步下降(P＜0.01),而RSG组GIR与HF组比较明显提高(P＜0.05).与OC组相比,HF组空腹血糖(FBG)、胰岛素(FINS)、游离脂肪酸(FFA)、血清甘油三酯(TG)和总胆固醇(TC)水平升高,而RSG组这些指标较HF组下降(P＜0.01或P＜0.05).肝脏TG含量在HF组高于OC组,RSG组低于HF组;肝脏TG含量与GIR呈负相关,与空腹血糖呈正相关.结论 高脂饮食导致老年大鼠肝脏脂质积聚及IR;罗格列酮干预可改善老年IR大鼠血浆脂代谢异常,降低肝脏脂质含量,提高胰岛素敏感性.     

Vitamin K and vascular calcification

Until recently, vitamin K has been exclusively related to blood coagulation. During the last decade, a second function for vitamin K-dependent proteins has become apparent : the regulation of tissue calcification. One of them is the function of Matrix Gla Protein (MGP) : potent inhibitors of vascular calcification. The function of MGP became clear from transgenic mice (MGP-deficient mice). Further research on MGP will resolve the complicated mechanism of atherosclerosis, especially of the arterial calcification. The recommended daily allowance for vitamin K to prevent vascular calcification should be evaluated.     

Vitamin K and bone quality

Dietary vitamin K intakes becomes reduced with aging. Low vitamin K intakes are associated with an increased incidence of hip fractures and an increase of under carboxylated osteocalcin in elderly men and women. The increase of under carboxylated osteocalcin is a risk factor for fractures in osteoporosis. Vitamin K2 treatment is effective for the prevention of fractures, but not for the increase of bone mineral density in osteoporosis. Vitamin K2 administration could be a potential treatment to improve the bone quality.     

K+-induced dilation of hamster cremasteric arterioles involves both the Na+/K+-ATPase and inward-rectifier K+ channels

OBJECTIVE: The mechanism by which elevated extracellular potassium ion concentration ([K+]o) causes dilation of skeletal muscle arterioles was evaluated. METHODS: Arterioles (n = 111) were hand-dissected from hamster cremaster muscles, cannulated with glass micropipettes and pressurized to 80 cm H2O for in vitro study. The vessels were superfused with physiological salt solution containing 5 mM KCl, which could be rapidly switched to test solutions containing elevated [K+]o and/or inhibitors. The authors measured arteriolar diameter with a computer-based diameter tracking system, vascular smooth muscle cell membrane potential with sharp micropipettes filled with 200 mM KCl, and changes in intracellular Ca2+ concentration ([Ca2+]i) with Fura 2. Membrane currents and potentials also were measured in enzymatically isolated arteriolar muscle cells using patch clamp techniques. The role played by inward rectifier K+ (KIR) channels was tested using Ba2+ as an inhibitor. Ouabain and substitution of extracellular Na+ with Li+ were used to examine the function of the Na+/K+ ATPase. RESULTS: Elevation of [K+]o from 5 mM up to 20 mM caused transient dilation of isolated arterioles (27 +/- 1 microm peak dilation when [K+]o was elevated from 5 to 20 mM, n = 105, p <.05). This dilation was preceded by transient membrane hyperpolarization (10 +/-1 mV, n = 23, p <.05) and by a fall in [Ca2+]i as indexed by a decrease in the Fura 2 fluorescence ratio of 22 +/- 5% (n = 4, p <.05). Ba(2+) (50 or 100 microM) attenuated the peak dilation (40 +/- 8% inhibition, n = 22) and hyperpolarization (31 +/- 12% inhibition, n = 7, p <.05) and decreased the duration of responses by 37 +/-11% (n = 20, p < 0.05). Both ouabain (1 mM or 100 microM) and replacement of Na+ with Li+ essentially abolished both the hyperpolarization and vasodilation. CONCLUSIONS: Elevated [K+]o causes transient vasodilation of skeletal muscle arterioles that appears to be an intrinsic property of the arterioles. The results suggest that K+-induced dilation involves activation of both the Na+/K+ ATPase and KIR channels, leading to membrane hyperpolarization, a fall in [Ca2+]i, and culminating in vasodilation. The Na+/K+ ATPase appears to play the major role and is largely responsible for the transient nature of the response to elevated [K+]o, whereas KIR channels primarily affect the duration and kinetics of the response.     

K+ channel openers activate brain sulfonylurea-sensitive K+ channels and block neurosecretion.

Vascular K+ channel openers such as cromakalim, nicorandil, and pinacidil potently stimulate 86Rb+ efflux from slices of substantia nigra. This 86Rb+ efflux is blocked by antidiabetic sulfonylureas, which are known to be potent and specific blockers of ATP-regulated K+ channels in pancreatic beta cells, cardiac cells, and smooth muscle cells. K0.5, the half-maximal effect of the enantiomer (-)-cromakalim, is as low as 10 nM, whereas K0.5 for nicorandil is 100 nM. These two compounds appear to have a much higher affinity for nerve cells than for smooth muscle cells. Openers of sulfonylurea-sensitive K+ channels lead to inhibition of gamma-aminobutyric acid release. There is an excellent relationship between potency to activate 86Rb+ efflux and potency to inhibit neurotransmitter release.     

Vitamin K2 and bone quality

Effects of vitamin K(2) (menatetrenone) and alendronate on bone mineral content and bone mechanical property in rats fed a low-magnesium diet. Recent clinical studies have shown that the occurrence of new fractures does not always depend on bone mineral density. Therefore bone quality has become an important issue in osteoporosis research. No animal model for evaluating bone quality has been established. In this study, we found that the treatment of rats with a low-magnesium (Mg) diet reduced their bone strength without decreasing bone mineral content (BMC), so the low Mg diet model is considered to be a good model for examining bone quality. Using this model, we investigated the effects of vitamin K(2) (V.K(2)) and alendronate (ALN). V.K(2) increased maximum load and elastic modulus without influencing BMC. ALN increased maximum load with increasing BMC. By using Fourier transform infrared microscopic analysis, the low-Mg diet treatment increased the mineral/matrix ratio of bones, and V.K(2) suppressed the increase in this ratio. These findings suggest that the mineral/matrix ratio may be a factor involved in bone quality, and that V.K(2) may improve bone quality.