脂质灌注对大鼠血浆抵抗素和ghrelin的影响*

目的：探讨脂质灌注对大鼠血浆抵抗素和ghrelin的影响。 方法： 采用正糖钳夹技术，在钳夹前后分别测定生理盐水对照组和脂质灌注组血浆抵抗素和ghrelin浓度，并用［3H］-葡萄糖作为示踪剂测定外周组织和肝糖的代谢。 结果： 脂质灌注组大鼠血浆游离脂肪酸（FFA）明显增加（P<0.01），葡萄糖输注率（GIR）明显降低（P<0.01）。对照组肝糖产率（HGP）明显被抑制（88%）。脂质输注组胰岛素对HGP的抑制作用明显减弱。在钳夹期间，脂质组与对照组比葡萄糖清除率（GRd）轻度降低。在正糖钳夹术结束时，对照组血浆ghrelin水平与钳夹前相比明显降低(P<0.05)。4 h的脂质灌注也引起了血浆ghrelin浓度的明显下降(P<0.05)，但是在钳夹结束时和对照组比没有明显差异。相关性分析表明空腹血浆ghrelin水平与空腹胰岛素和血糖呈明显负相关（r=-0.52和r=-0.61, P<0.05）。脂质灌注后大鼠血浆抵抗素水平较灌注前和对照组明显升高（P<0.01），空腹血浆抵抗素浓度与空腹FFA（r=0.68, P<0.01）、血糖（r=0.66, P<0.01）呈明显正相关。 结论： 脂质灌注诱导了肝脏和外周的胰岛素抵抗，抵抗素在胰岛素抵抗的形成中可能具有重要作用。高胰岛素血症，而不是游离脂肪酸，降低了大鼠循环ghrelin水平。     

吡格列酮对脂质灌注大鼠糖代谢和PPAR-γ表达的影响

目的：探讨吡格列酮 (Pio) 对游离脂肪酸诱导的胰岛素抵抗大鼠糖代谢和PPAR-γ表达的影响。方法:采用扩展正糖钳夹实验和［3-3H］标记葡萄糖示踪技术，观察了4 h脂质灌注导致大鼠血浆游离脂肪酸（FFA）升高引起糖代谢和脂肪组织PPAR-γ表达变化及Pio处理后的影响。 结果:在钳夹稳态期，对照组（N组）血浆FFA水平明显降低，而脂质灌注组（L组）和吡格列酮+脂质组（P/L组）FFA水平明显升高。 P/L组葡萄糖输注率(GIR)较N组明显降低（P<0.01）, 而L组又明显低于P/L组（P<0.01）；N组和P/L组肝糖输出 (HGP) 与基础值相比被明显抑制达85%（均P<0.01），在L组，胰岛素对HGP的抑制作用受到明显障碍（仅抑制8.7%）。L组和P/L组葡萄糖清除率（GRd）明显低于N组（P<0.01）。P/L组脂肪组织PPAR-γ表达明显增加。 结论:脂质灌注诱导了大鼠胰岛素抵抗。吡格列酮干预使大鼠脂肪组织PPAR-γ表达明显增加，并抑制了内源性肝糖产生，从而部分逆转了脂质诱导的胰岛素抵抗。     

清醒大鼠胰岛素钳夹术及其糖代谢变化

为准确地评价在体组织对胰岛素 (Ins)的敏感性及探讨在胰岛素抵抗 (IR)状态下机体糖代谢变化。采用 6 ,6 D2 葡萄糖作为示踪剂 ,建立了自由状态下大鼠正常血糖 -高胰岛素钳夹术 ,并动态观察了其体内糖代谢的动态改变及血浆游离脂肪酸 (FFA)和Ins浓度随时间变化的过程。大鼠在 4 8mU (kg·min)速率Ins输注下 ,血糖稳定在正常水平而肝糖输出被抑制 ,胰岛素介导的机体葡萄糖利用率较基础状态显著增加 ,游离脂肪酸 (FFA)浓度显著下降。本钳夹术平均血糖变异系数为 5 76 %。平均GIR变异系数为 6 2 5 % ,GRd为 9 17%。重复试验GIR与GRd误差范围为 1 2 %和 1 7%。以 6 ,6 D2 葡萄糖作为示踪剂建立的自由状态下的大鼠正常血糖钳夹技术具有准确、可靠 ,无放射污染等优点 ,在外源性胰岛素 -葡萄糖代谢稳定状态下 ,机体对葡萄糖利用显著增加 ,脂肪分解显著减少。     

国产格列美脲药效学试验研究

为观察国产格列美脲的降血糖作用及对胰岛素分泌的影响,将大鼠、家兔灌服格列美脲2.5mg/kg、5mg/kg、10mg/kg后,通过测血糖、耐糖试验和测血浆胰岛素水平研究格列美脲的作用。结果显示,给药后血糖均明显降低(P<0.01),且药效强于格列本脲;大鼠灌服2.5mg/kg格列美脲已能明显对抗糖负荷引起的血糖升高,随给药剂量升高对抗作用增强;家兔灌服该药上述三种剂量后亦明显对抗糖负荷引起的血糖升高;大鼠和家兔灌服格列美脲后血清胰岛素水平上升,其升高程度与给药剂量正相关。以上结果表明格列美脲能刺激胰岛并增加胰岛素的分泌,对比实验表明格列美脲促胰岛素分泌作用强于格列本脲。     

双(α-呋喃甲酸)氧钒对STZ大鼠血糖的影响

目的 :研究双 (α 呋喃甲酸 )氧钒 (VO FA)对正常大鼠及链脲佐霉素 (STZ)性糖尿病大鼠的降糖作用及其对血清胰岛素等的影响。方法以STZ (5 0mg/kg)腹腔注射诱导SD大鼠形成糖尿病模型。动物随机分为正常对照组、正常给药组 (VO FA 1 0mgV·kg 1)、糖尿病模型组和低 (VO FA 5mgV·kg 1)、中 (VO FA1 0mgV·kg 1)高剂量 (VO FA 2 0mgV·kg 1)治疗组。灌胃 (ig)给药 ,每天 1次 ,共 4周。每周观测血糖和体重。给药 4周后观察药物对糖化血红蛋白、糖原和血清胰岛素等的影响。用自动生化分析仪测定血糖、血脂、糖化血红蛋白和糖原 ;放…     

番石榴叶总三萜对2型糖尿病大鼠的降血糖和血脂作用

目的: 探讨番石榴叶总三萜(TTPGL)对2型糖尿病大鼠血糖及血脂的影响。方法: 采用高糖高脂饮食加腹腔注射小剂量链脲佐菌素(STZ, 35 mg·kg^-1)方法建立2型糖尿病大鼠模型。将造模成功的糖尿病大鼠随机分为5组:糖尿病模型组,TTPGL低、中、高剂量组(60、120、240 mg·kg^-1),罗格列酮阳性对照组(3 mg·kg^-1)。另取12只正常大鼠设为正常对照组。给药组每天灌胃给药1次,连续给药6周;模型组和正常对照组则给予同体积的生理盐水灌胃。给药6周后,采用葡萄糖氧化酶法测定大鼠的空腹血糖(FBG);放射免疫法测定空腹胰岛素(FINS),并计算胰岛素敏感指数(ISI);酶联免疫法测定大鼠的甘油三酯(TG)、总胆固醇(TCH)、游离脂肪酸(FFA)和糖化血红蛋白(GHb);果糖胺法测定糖化血清蛋白(GSP);Western blotting检测脂肪组织过氧化物酶体增殖物激活受体γ(PPARγ)的表达情况。结果: 与正常对照组相比,糖尿病模型组血脂、FBG以及GHb显著升高,FINS及ISI显著下降,脂肪细胞PPARγ蛋白表达水平降低。与模型组相比,TTPGL中、高剂量组大鼠的FBG和GSP显著降低,FINS以及ISI显著升高,脂肪组织PPARγ蛋白的表达水平升高(P<0.01或P<0.05);此外,TTPGL能显著降低糖尿病大鼠血脂水平,TG、TCH和FFA含量均明显降低(P<0.01或P<0.05)。结论: TTPGL能显著降低2型糖尿病大鼠的血糖和血脂水平,明显改善糖尿病动物的糖脂代谢紊乱,升高血清胰岛素水平,提高胰岛素敏感指数;其抗糖尿病作用机制可能与其增加PPARγ蛋白的表达有关。     

抗苗勒氏管激素与多囊卵巢综合症治疗效果的相关性

目的:研究多囊卵巢综合症治疗效果和抗苗勒氏管激素(Anti-Mullerian hormone,AMH)的相关性。方法:收集我院门诊2015年11月至2016年2月多囊卵巢综合征不孕症患者,排除其他因素后纳入140例。根据患者空腹血糖、空腹胰岛素和雄激素值分组:对照组:空腹血糖、空腹胰岛素和雄激素正常;糖代谢异常组:空腹血糖或/和空腹胰岛素升高,雄激素正常;高雄激素组:雄激素升高,空腹血糖或/和空腹胰岛素正常;糖代谢异常合并高雄激素组:空腹血糖或/和空腹胰岛素升高和雄激素升高的。给予达英-35或/和二甲双胍治疗后比较各组治疗前后和组间的抗苗勒氏管激素(Anti-Mullerian hormone,AMH)、空腹血糖、空腹胰岛素、胰岛素抵抗指数和雄激素变化。结果:糖代谢异常组,高雄激素组和糖代谢异常合并高雄激素组的AMH值,明显高于对照组(P0.05)。其中糖代谢异常合并高雄激素组的AMH值明显高于糖代谢异常组及高雄激素组(P0.05)。药物治疗后各组的AMH值比未治疗前均有明显下降(P0.05)。结论:AMH、糖代谢和雄激素三者可能具有互相影响、互相作用的关系。血清AMH水平为诊断和研究PCOS提供了一个重要的突破点。     

高果糖诱导的胰岛素抵抗大鼠外周血白细胞iNOS mRNA与ecNOS mRNA表达的变化

目的:探讨高果糖饮食对Wistar大鼠外周血白细胞iNOSmRNA与ecNOSmRNA表达的影响。方法:普通饲料喂养,实验组饮用12 %的果糖水造型。于实验前、实验过程中1-6个月每月断尾取血,测定外周血白细胞诱导型一氧化氮合酶mRNA(iNOSmRNA)与内皮源型一氧化氮合酶mRNA (ecNOSmRNA)表达;观察实验前、造型1、2、3及 6个月时的空腹血糖、血浆胰岛素水平变化。结果:1个月后,血糖与实验前无显著差异;血浆胰岛素明显高于对照组 (P <0.01),并持续维持在高水平上;外周血白细胞ecNOSmRNA表达增强。 2个月后血糖高于对照组 (P <0.05);外周血白细胞出现iNOSmRNA表达。 3及 6个月,血糖明显高于对照组 (P <0.01);iNOSmRNA与ecNOSmR NA持续保持高表达状态。结论:高果糖饮食两个月,可引起Wistar大鼠产生明显的高胰岛素血症和胰岛素抵抗;首先ecNOSmRNA表达增强,可能延缓胰岛素抵抗的形成。继之,iNOSmRNA表达增强,可能促进胰岛素抵抗形成.     

香附总黄酮对糖尿病大鼠血糖血脂及抗氧化活性的影响

目的探讨香附总黄酮对糖尿病大鼠血糖、血脂及抗氧化活性的影响。方法 65只SD大鼠随机选10只为空白组(给予标准饲料);其余为造模组(给予高脂高糖饲料及链脲佐菌素腹腔注射),将造模成功的50只大鼠随机分为阳性药组(10 mg/kg二甲双胍)、高剂量组(200 mg/kg)、中剂量组(100 mg/kg)、低剂量组(50 mg/kg),每组10只。给药1个月后,取各组大鼠血及肝肾,检测血糖水平,检测血清中甘油三酯(TG)、血清总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)及高密度脂蛋白胆固醇(HDL-C)含量,检测血清、肝肾匀浆中过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-PX)与超氧化物歧化酶(SOD)含量。结果给药后,香附总黄酮高、中及低剂量组大鼠血糖、TG、TC及LDL-C水平均明显低于模型组,HDL-C值则明显高于模型组(P0.05)。给药后,香附总黄酮高、中及低剂量组大鼠血清、肾匀浆及肝匀浆中CAT、SOD及GSH-PX含量均明显高于模型组(P0.05)。结论香附总黄酮对糖尿病大鼠具有较好的治疗作用,且可有效降血糖,调节血脂及氧化应激紊乱。     

内源性精氨酸加压素在索曼引起的大鼠体温降低中的作用

目的:探讨内源性精氨酸加压素是否参与索曼引起的降温过程。方法:用数字体温计测量大鼠的体温,每次间隔60 min,观察了腹腔注射AVP V₁受体阻断剂(30 μg/kg)对皮下注射索曼(60 μg/kg)引起大鼠降温效应的影响,以及给索曼后2 h血浆中AVP含量的变化。结果:给索曼后可引起明显的体温降低,在给药后7 h体温恢复到基线水平。AVP V₁受体阻断剂能明显阻断索曼的降温效应。在给索曼后2 h血浆中AVP浓度明显提高。结论:实验结果证明内源性AVP参与索曼引起的降温过程。     

原发性高血压患者糖负荷后血糖和胰岛素变化对游离脂肪酸水平的影响

目的:探讨糖负荷后血糖和胰岛素变化对血清游离脂肪酸(FFA)水平的影响。方法: 234例高血压病患者[2型糖尿病(DM)20例,糖耐量低减(IGT)74例,正常糖耐量(NGT)140例;男98例,女136例]做口服葡萄糖耐量试验(OGTT),测定0、30、60、120 min时相的葡萄糖、血清胰岛素和FFA水平。结果: 空腹血清FFA浓度(μmol/L):DM组(1 048.7±481.6)显著高于IGT组(706.1±332.1)(P＜0.05)和NGT组(725.8±353.9)(P＜0.05)。DM组OGTT血糖水平显著升高,胰岛素释放曲线呈反应低平,高峰不明显或呈延迟相。3组FFA释放均呈低下,DM组更为显著。30、60、120 min时相的血清FFA水平,3组均无显著差异。结论: 糖尿病患者空腹血清FFA水平升高,OGTT中糖尿病患者胰岛素分泌的绝对不足未能增大DM组FFA水平与IGT及NGT组的差异,相反缩小了与IGT和NGT组的差距,提示体内葡萄糖利用水平对血清FFA浓度可能有重要的影响。     

Surgical removal of visceral fat decreases plasma free fatty acid and increases insulin sensitivity on liver and peripheral tissue in monosodium glutamate (MSG)-obese rats

In order to evaluate the role of visceral and subcutaneous fat tissue in insulin sensitivity and lipid metabolism, we measured the fasting levels of plasma free fatty acid (FFA) and insulin, glucose disappearance rate (Rd), and hepatic glucose production rate (HGP) after surgical removal of visceral (VF) or subcutaneous (SF) fat tissue in monosodium glutamate-obese (MSG-Ob) rats. Monosodium glutamate obesity was induced in rats by neonatal injection of MSG. Surgery to remove fat was done at 15 weeks of age. The experiments were done four weeks after the surgery. MSG-Ob rats showed increased levels of FFA, insulin, and HGP and decreased Rd compared to normal rats. In the VF group, the FFA level and HGP were decreased to normal values, Rd was partially normalized, but the level of insulin did not change significantly compared to MSG-Ob. In the SF group, FFA and Rd were partially normalized, but HGP was not suppressed significantly compared to MSG-Ob. These results suggest that visceral fat affects the insulin sensitivity of liver and FFA concentration more than subcutaneous fat; however, no significant difference was shown on whole body insulin sensitivity and fasting insulin concentration.     

Effects of phlorizin and acipimox on insulin resistance in STZ-diabetic rats.

To evaluate the roles of hyperglycemia and increased plasma FFA level in the development of insulin resistance, we examined the effects of phlorizin and acipimox treatments on tissue sensitivity to insulin in streptozotocin(STZ)-diabetic rats. Insulin sensitivity was assessed with the glucose-insulin clamp technique. Blood glucose concentration was clamped at basal levels of control and diabetic states, and plasma insulin concentrations were clamped at the levels of basal, approximately 60 and approximately 1500 microU/ml. In diabetic rats, the basal blood glucose and plasma FFA levels in the fasting state were elevated, while the plasma insulin concentration was lower than in normal controls. Moreover, diabetic rats became glucose intolerant after intravenous injection of glucose. The metabolic clearance rate(MCR) of glucose showed a decrease of basal and insulin stimulated response in diabetic rats. As results of the glucose-insulin clamp study and intravenous glucose tolerance test, insulin resistance was developed in STZ-diabetic rats. Phlorizin treatment of diabetic rats recovered insulin sensitivity to nearly normal levels and improved glucose tolerance, but had no effect on insulin action in controls. Insulin sensitivity was also improved by acipimox treatment in diabetic rats, but did not reach normal levels. These results show that hyperglycemia is an obvious causative factor of insulin resistance, and increased FFA level may also act on the development of insulin resistance in STZ-diabetic rats.     

Extracellular distribution of insulin in muscle of rats exposed to long-term hyperinsulinaemia

The importance of increased capillary density for the regulation of insulin sensitivity by transcapillary delivery of insulin to muscle cells in insulin-exposed rats was investigated by direct microdialysis measurements of interstitial [¹²⁵I]insulin concentrations in the femoral muscle during an euglycaemic hyperinsulinaemic clamp. In insulin-exposed rats plasma insulin was ～25% (P<0.05) higher than that in control animals during the first 100 min and reached their maximal concentrations after 100 min. After a nitroprusside infusion given at 100 min both groups had similar concentrations of insulin in plasma as well as in muscle interstitial fluid. However, mean glucose infusion rate during the first clamp hour was 20.5±2.3 and 12.6±5.2 mg kg^-1 min^-1 (P<0.05) in insulin-exposed and control animals, respectively. During the second clamp hour the corresponding figures were 21.1±2.4 and 13.9±2.6 (P<0.05). It may be concluded that capillarization and/or nitroprusside affected plasma insulin concentrations without altering either the interstitial insulin levels or the insulin effect on glucose consumption. The data suggest that the elevated insulin sensitivity after chronic insulin exposure is dependent on other than transcapillary transport events and demonstrate the different kinetics for insulin distribution in plasma and in the interstitial fluid.     

Decreased microvascular vasomotion and myogenic response in rat skeletal muscle in association with acute insulin resistance

In addition to increased glucose uptake, insulin action is associated with increased total and microvascular blood flow, and vasomotion in skeletal muscle. The aim of this study was to determine the effect of acute insulin resistance caused by the peripheral vasoconstrictor α-methylserotonin (αMT) on microvascular vasomotion in muscle. Heart rate (HR), mean arterial pressure (MAP), femoral blood flow (FBF), whole body glucose infusion (GIR) and hindleg glucose uptake (HGU) were determined during control and hyperinsulinaemic euglycaemic clamp conditions in anaesthetized rats receiving αMT infusion. Changes in muscle microvascular perfusion were measured by laser Doppler flowmetry (LDF) and vasomotion was assessed by applying wavelet analysis to the LDF signal. Insulin increased GIR and HGU. Five frequency bands corresponding to cardiac, respiratory, myogenic, neurogenic and endothelial activities were detected in the LDF signal. Insulin infusion alone increased FBF (1.18 ± 0.10 to 1.78 ± 0.12 ml min^–1, P < 0.05), LDF signal strength (by 16% compared to baseline) and the relative amplitude of the myogenic component of vasomotion (0.89 ± 0.09 to 1.18 ± 0.06, P < 0.05). When infused alone αMT decreased LDF signal strength and the myogenic component of vasomotion by 23% and 27% respectively compared to baseline, but did not affect HGU or FBF. Infusion of αMT during the insulin clamp decreased the stimulatory effects of insulin on GIR, HGU, FBF and LDF signal and blocked the myogenic component of vasomotion. These data suggest that insulin action to recruit microvascular flow may in part involve action on the vascular smooth muscle to increase vasomotion in skeletal muscle to thereby enhance perfusion and glucose uptake. These processes are impaired with this model of αMT-induced acute insulin resistance.     

一氧化氮抑制剂对腹膜透析大鼠腹膜形态及表面层的影响

目的:探讨高糖透析液对大鼠腹膜巨噬细胞一氧化氮(NO)的产生、诱导型一氧化氮合酶(iNOS)的表达和腹膜透析通透性的影响以及NO抑制剂的保护作用。方法: 培养生理盐水、1.5％和4.25％葡萄糖透析液透析下的大鼠腹腔内的巨噬细胞, 检测细胞培养上清液NO的浓度和巨噬细胞iNOS的表达, 并观察1.5％及4.25％葡萄糖透析液和NO抑制剂透析下大鼠的液体超滤量和腹膜形态的变化。结果:大鼠腹腔内巨噬细胞NO的产生随透析液中葡萄糖含量增加而增加;腹腔巨噬细胞iNOS的表达, 葡萄糖透析组明显高于生理盐水组;NO抑制剂对光镜下腹膜形态无影响, 但明显减轻4.25%葡萄糖透析液对超滤量和腹膜表面层的减少作用。结论:一氧化氮抑制剂可明显改善高糖透析大鼠的腹膜通透性, 并减轻高糖对腹膜表面层的损伤。     

Insulin sensitivity in patients with arterial insufficiency. Re-evaluation with the multilevel glucose clamp technique

Previous studies have claimed that changes in insulin and glucose metabolism in patients with peripheral arterial insufficiency indicate an increased sensitivity to insulin for glucose uptake. We have re-evaluated this concept in 11 patients with intermittent claudication and 11 matched controls with a multilevel euglycaemic glucose clamp technique. The groups were matched for age, sex and body composition but not completely for smoking habits and physical fitness. Although the control group had a normal physical fitness the patients had 40% lower maximal exercising capacity. The patients' maximal walking capacity was 186 +/- 27 m evaluated on a treadmill. No patient with ischaemic ulcers or rest pain were included. The euglycaemic glucose clamp was performed at five insulin plateau levels (70, 110, 190, 590 and 1440 mU/l) of one h duration each and whole body glucose uptake during the last 20 min was calculated. No differences in maximal glucose uptake (Vmax) or insulin level for half maximal glucose uptake (Km) between the groups were observed. The concentration or the magnitude of the decrease in arterial FFA levels did not differ significantly between the groups at any physiological insulin level. This study can not confirm previously described changes in insulin sensitivity in patients with arterial insufficiency. Although the discrepancy between present and previous results remains unclear it may reflect the combined effects of different methods used, including the selection of reference patients, rather than an increased insulin sensitivity in patients with arterial insufficiency. This study suggests that previous conclusions based on glucose tolerance tests should be interpreted with caution.