大豆纤维对糖尿病模型鼠的干预治疗效果

以链脲佐霉素（ｓｔｒｅｐｔｏｚｏｔｏｃｉｎ,ＳＴＺ）诱导制作的糖尿病（ＤＭ）小鼠和正常小鼠为对象,观察予以大豆纤维饲养后ＤＭ模型鼠的血糖、血脂的变化。饲养５周后,食用含１０％大豆纤维饲料的ＤＭ小鼠,血糖由（２１．２９±２．５１）ｍｍｏ１／Ｌ下降至（１０．２５±３．７１）ｍｍｏ１／Ｌ（Ｐ＜０．００１）,血清总胆固醇（ＴＣ）和甘油三酯（ＴＧ）较对照组也均明显降低（Ｐ＜０．０５）,高密度脂蛋白胆固醇（ＨＤＬ—Ｃ）较对照组明显增高（Ｐ＜０．０５）;同期予以普通饲料喂养的ＤＭ小鼠血糖由（２０．４５±２．７３）ｍｍｏ１／Ｌ升高至（２６．１６±３．０７）ｍｍｏ１／Ｌ,提示大豆纤维具有显著的降糖、降脂作用。     

链脲佐菌素致糖尿病小鼠模型的建立及抗氧化能力的影响

目的探讨一次性腹腔注射链脲佐菌素（Streptozocin,STZ）诱导糖尿病模型的最适剂量及成模小鼠机体抗氧化能力的改变。方法选80只小鼠随机分为4组：正常对照组、100mg·kg^-1、150mg·kg^-1、200mg·kg^-1 STZ 3个剂量组（M1、M2、M3）,采用一次性腹腔注射不同剂量STZ,7d后观察小鼠的造模成功率、死亡率、体重变化、空腹血糖及血清T-SOD、MDA值。结果随着一次性腹腔注射链脲佐菌素剂量的增加,小鼠体重减轻明显,空腹血糖值显著性升高（P〈0．01）,血清T-SOD值明显下降（P〈0．01）,血清MDA含量明显增加（P〈0．01）。结论一次性腹腔注射STZ 150mg·kg^-1时,小鼠成模率高、死亡率低、糖尿病模型稳定,为最适造模剂量;成模小鼠机体抗氧化能力较正常小鼠明显下降。     

仙人掌多糖主要组分对糖尿病小鼠的免疫调节作用

目的研究野生仙人掌多糖(Opuntia dillenii Haw.Polysaccharides,ODPs)对糖尿病(DM)小鼠免疫调节作用的影响。方法建立链脲佐菌素(STZ)+环磷酰胺(Cy)诱导的DM免疫功能低下复合模型,观察ODPs主要组分ODP-I对DM小鼠NO含量、腹腔巨噬细胞的吞噬功能、血清IgM和IgG的含量、脾淋巴细胞增殖反应、外周血T淋巴细胞亚群比例的影响。结果 400 mg/kg ODP-I能调节DM小鼠NO至正常水平;极显著增强DM小鼠巨噬细胞的吞噬功能;显著提高DM小鼠血清IgM或IgG的含量;显著提高DM小鼠T、B淋巴细胞的增殖能力,且使之恢复至正常水平;能通过提高CD8+T细胞亚群比例,降低CD4+/CD8+T细胞比值,使之恢复至正常水平,改善DM小鼠的免疫紊乱现象。结论 ODP-I能从DM小鼠的非特异性免疫、体液免疫、细胞免疫方面增强DM小鼠的免疫功能,改善DM症状,效果优于阳性对照药左旋咪唑。     

克糖特对糖尿病模型小鼠血糖的影响

目的:研究克糖特(KTF)对糖尿病模型小鼠血糖的影响,并初步探讨其降低小鼠血糖的作用机制。方法:建立链脲霉素(STZ)致糖尿病小鼠模型。将小鼠随机分为5组(n=10),分别用格列本脲(50 mg·kg~(-1))、高、中、低剂量克糖特和0.9%氯化钠溶液(0.1 ml/10g体重)灌胃15d。15d后测定正常小鼠的血糖水平,并在相应时间测定STZ致糖尿病小鼠模型空腹血糖(FBG)、药后2h血糖(2h BG)、胰岛素水平,同时对STZ所致糖尿病小鼠进行胰腺病理组织学检查。结果:克糖特对正常小鼠血糖水平无影响,能够显著降低STZ模型小鼠空腹血糖(与模型组比较降糖率可达24.39%,P<0.05～0.01)和药后2 h BG(P<0.05),明显提高胰岛素水平(P<0.05～0.01),保护胰岛β细胞。结论:克糖特对STZ引起的高血糖有较好的降糖作用,其作用机制可能与改善受损的胰岛细胞功能,促进胰岛素分泌有关。     

Exendin-4对非糖尿病小鼠的血糖和糖耐量的影响

目的:观察exendin4对非糖尿病小鼠的血糖和糖耐量的影响。方法:非糖尿病小鼠分为exendin4(Exe4)各剂量组和生理盐水(NS)组。腹腔内注射Exe40.1μg·g-1,观察注射1h后、连续注射10d期间和停药后2wk内血糖,并于停药后20d行腹腔葡萄糖耐量试验(IPGTT)。另外,非糖尿病小鼠每日注射不同剂量Exe40.1,0.2,0.4μg·g-1×3d,观察每日血糖。结果:非糖尿病小鼠注射Exe40.1μg·g-11h后血糖为(6.2±s1.3)mmol·L-1,低于NS组(10.6±1.1)mmol·L-1,P<0.01。连续注射Exe4期间的平均血糖以及停药后2wk内的平均血糖与NS组比较,均无明显差异,P>0.05;且IPGTT中2组各点血糖差异无显著意义,不同剂量Exe4注射组小鼠的3d平均血糖与NS组比较也无明显差别。结论:Exe4对非糖尿病小鼠的血糖具有即刻降低作用,但是每日1次腹腔内注射对非糖尿病小鼠的血糖和糖耐量无明显影响。     

建立小鼠2型糖尿病模型时链脲佐菌素剂量的研究

目的：研究链脲佐菌素（STZ）注射剂量对建立2型糖尿病小鼠模型的影响。方法：不同文献中STZ的注射剂量不一致。本文以存活率和成模率两个因素为指标,采用高脂饲料喂养加不同浓度梯度的链脲佐菌素（STZ）注射建立2型糖尿病模型。结果：50mg/Kg剂量组小鼠虽然全部存活,成模率为0;100mg/Kg剂量组全部存活,成模率20%;150mg/Kg剂量组死亡率达70%,但存活下来的30%全部成模;200mg/Kg剂量组的小鼠全部死亡。结论：125mg/Kg是此方法中的STZ最佳剂量。     

人工虫草多糖对2型糖尿病小鼠胰岛素抵抗的影响

目的 观察人工虫草多糖对2型糖尿病小鼠胰岛素抵抗的影响及作用机制. 方法 采用高脂饲料(fat-fed,FF)联合腹腔注射小剂量链脲佐菌素(STZ,25 mg&#8226;kg^-1)建立胰岛素抵抗2型糖尿病模型(T2DM-IR),每日给予不同剂量人工虫草多糖(200,400 mg&#8226;kg^-1)治疗,连续28 d. 观察实验小鼠体质量、空腹血糖的变化. 末次给药前小鼠禁食12 h,测定口服糖耐量. 随后眼球取血,检测血清胰岛素、三酰甘油(TG)、总胆固醇(TC)、游离脂肪酸(FFA),计算胰岛素抵抗指数(HOMA-IR). 结果FF/STZ诱导的实验性小鼠,出现以腹型肥胖、血糖及胰岛素水平异常等T2DM-IR典型症状. 人工虫草多糖可剂量依赖性地改善糖尿病小鼠糖耐量及胰岛素抵抗指数,同时降低血清胰岛素、TG、TC、FFA水平. 结论 400 mg&#8226;kg^-1人工虫草多糖可明显降低FF/STZ诱导的T2DM-IR模型小鼠血糖与血脂,改善胰岛素抵抗,作用机制可能与增强胰岛素受体敏感性有关.     

尾静脉注射不同剂量链脲佐菌素对大鼠血糖的影响

目的：探讨不同剂量链脲佐菌素（STZ）对大鼠血糖的影响。方法：尾静脉分别注射65mg/kg、25mg/kgSTZ,在48h、2周测血糖,观察血糖的变化。结果：大鼠尾静脉注射65mg/kg STZ,48h后引起血糖升高;大鼠尾静脉注射25mg/kg,2周后形成糖耐量异常。结论：65mg/kgSTZ给大鼠尾静脉注射,造成类似I型糖尿病模型：25mg/kg STZ形成糖耐量异常大鼠。     

苣荬菜水煎液对糖尿病大鼠的降血糖作用及其机制

目的观察苣荬菜水煎液对链脲佐菌素致糖尿病大鼠模型的降血糖作用及其机制。方法采用一次性腹腔注射链脲佐菌素的方法制作大鼠糖尿病模型,将大鼠分为空白组,模型组,二甲双胍组(0.47 g·kg^-1),苣荬菜水煎液高、中、低剂量组(3.34,1.67,0.83 g·kg^-1),实验中监测血糖,并检测各组大鼠血清中超氧化物歧化酶(superoxide dismutase,SOD)活力,丙二醛(malondialdehyde,MDA)、谷光甘肽(glutathione,GSH)、一氧化氮(nitric oxide,NO)、总胆固醇(total cholesterol,TC)、低密度脂蛋白(low density lipoprotein,LDL)、高密度脂蛋白(high density lipoprotein,HDL)、甘油三酯(triglyceride,TG)、糖基化血清蛋白(glycosylated serum protein,GSP)、胰岛素(insulin,INS)、胰岛素抗体(insulin antibody,IAA)水平和一氧化氮合酶(nitricoxidesynthase,NOS)活力,并采用HE染色法观察大鼠胰腺和肾脏组织病理变化。结果与空白组相比,模型组大鼠血糖值及血清NOS活力,MDA、NO、TC、LDL、TG、GSP、IAA水平显著升高(P<0.01),SOD活力,GSH、HDL、INS水平显著降低(P<0.01);与模型组相比,二甲双胍组和苣荬菜水煎液组各剂量均可不同程度降低血糖水平,二甲双胍组与苣荬菜水煎液高剂量组可显著升高SOD活力,GSH、HDL、INS水平(P<0.01),显著降低NOS活力,MDA、NO、TC、LDL、TG、GSP、IAA水平(P<0.01或P<0.05),改善胰腺、肾脏的病理变化。结论苣荬菜水煎液具有较好的降血糖效果,其作用机制与促进胰岛β细胞释放胰岛素有关,并可修复胰岛细胞组织、保护肾脏。     

柚皮素对糖尿病肝损伤小鼠的保护作用

目的观察柚皮素对糖尿病肝损伤小鼠的保护作用。方法高糖高脂饲料喂养4周后采用小剂量链脲佐菌素(STZ)连续5 d腹腔注射建立小鼠糖尿病模型,制模7 d后随机分为模型组,柚皮素低、中、高剂量(30、 60、 120 mg·kg~(-1)·d~(-1))组和阳性对照(二甲双胍120 mg·kg~(-1)·d~(-1))组(n=15),另选正常小鼠分为正常对照组和正常给药(柚皮素120 mg·kg~(-1)·d~(-1))组(n=6),连续灌胃给药8周,监测小鼠空腹血糖(FBG)。小动物超声检测肝脏病理改变,取血检测小鼠血脂和肝功能水平,肝脏称重,采用HE染色和油红O染色检查小鼠肝脏组织病理学和脂质沉积情况。结果与正常对照组比较,模型组小鼠FBG显著增高(P <0.05);肝肾回声比值和肝脏指数显著增加(P <0.05);血总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)和高密度脂蛋白胆固醇(HDL-C)水平均显著增加(P <0.05);肝功能天冬氨酸转氨酶(AST)、丙氨酸转氨酶(ALT)显著增加(P <0.05),而白蛋白(ALB)、 ALB-球蛋白(GLOB)比值显著降低(P <0.05)。正常给药组与正常对照组比较各指标均无显著变化(P>0.05)。与模型组比较,柚皮素中、高剂量组FBG和肝肾回声比值均显著降低(P <0.05);柚皮素高剂量组肝脏指数降低(P <0.05), TC、 TG和LDL-C水平显著下降(P <0.05), HDL-C显著升高(P <0.05),AST和ALT显著降低(P <0.05), ALB显著上升(P <0.05);柚皮素高剂量组和阳性对照组比较各指标均无显著差异(P> 0.05)。结论柚皮素可降低糖尿病肝损伤小鼠血糖,改善血脂水平和肝功能,减少肝脏脂质蓄积。     

Neuroprotective effect of the glucagon-like peptide-1 receptor agonist, synthetic exendin-4, in streptozotocin-induced diabetic rats

BACKGROUND AND PURPOSE

Glucagon-like peptide-1 (GLP-1) receptors are widely expressed in neural tissues and diminish neuronal degeneration or induce neuronal differentiation. The aim of this study was to investigate the effect of the GLP-1 pathway on peripheral nerves in streptozotocin-induced diabetic rats.

EXPERIMENTAL APPROACH

Diabetic and nondiabetic rats were treated with the GLP-1 receptor agonist, synthetic exendin-4 (i.p., 1 nmol·kg⁻¹·day⁻¹) or placebo for 24 weeks, and current perception threshold values, cAMP levels and nerve fibre size in the sciatic nerve were measured. We also investigated GLP-1 receptor expression, quantitative changes in PGP9.5-positive intraepidermal nerve fibres and cleaved caspase 3–stained Schwann cells by immunohistochemistry.

KEY RESULTS

GLP-1 receptor expression was detected in the sciatic nerve and skin. After exendin-4 treatment, the increase seen in current perception threshold values at 2000 and 250 Hz in diabetic rats was reduced. Also, the decrease in myelinated fibre size or axon/fibre area ratio in the sciatic nerve and the loss of intraepidermal nerve fibre in the skin of diabetic rats were ameliorated. These responses were closely associated with the attenuation of Schwann cell apoptosis and improvement in the cAMP level in exendin-4-treated diabetic rats, compared with placebo-treated animals.

CONCLUSION AND IMPLICATIONS

Synthetic exendin-4 may prevent peripheral nerve degeneration induced by diabetes in an animal model, supporting the hypothesis that GLP-1 may be useful in peripheral neuropathy. The neuroprotection is probably attributable to GLP-1 receptor activation, antiapoptotic effects and restoration of cAMP content.     

Exendin-4与神经退行性疾病的关系

Exendin-4是一种糖尿病新药,也是胰高血糖素样肽-1(GLP-1)类似物,能激活GLP-l受体,上调cAMP发挥生理活性。GLP-1受体与神经元可塑性及存活密切联系。Exendin-4还能激活多条信号通路,调节胞内钙离子(Ca2+)稳态,减轻兴奋性毒性,抑制细胞凋亡,促进神经元增生、分化,对神经退行性疾病有治疗作用。该文旨在阐明exendin-4的神经保护机制,为神经退行性疾病的预防与治疗提供新思路。     

醋酸艾塞那肽在大鼠体内的代谢分布(英文)

目的研究醋酸艾塞那肽(exendin-4)在大鼠体内的组织分布。方法Iodo-GenTM法制备[125I]exendin-4,大鼠皮下注射[125I]exendin-4后,分别测定血浆或组织中的总放射性含量和酸沉淀放射性含量。结果[125I]exendin-4的酸沉淀放射性分布从高到低的顺序为肾脏>肺>膀胱>胰腺>肠>血浆>肾上腺>空肠>淋巴结>肝>脾>心脏>骨髓>胸腺>睾丸>脑>肌肉>脂肪。结论[125I]ex-endin-4的分布快速而广泛,其中以肾脏中最高,而在脑组织只发现微量的[125I]exendin-4。     

新型糖尿病治疗药物exendin-4的研究进展

Exendin-4(降血糖药)是首个在美国获准上市用于治疗2型糖尿病的肠促胰岛素拟似物。临床研究表明,其与二甲双胍、磺酰脲类药物、或噻唑烷二酮类药物合用,能有效地控制2型糖尿病患者的血糖。Exendin-4的作用机制包括葡萄糖依赖的促胰岛素分泌、抑制胰高血糖素分泌、增加β细胞质量、减缓胃排空和抑制食欲。近来还发现,exendin-4可增加胰岛移植受者的胰岛素分泌量。Exendin-4对中枢神经系统也有保护作用。本文对ex-endin-4的药理作用及其机制、药物特点等作一综述。     

Autonomic nervous system-dependent and -independent cardiovascular effects of exendin-4 infusion in conscious rats

BACKGROUND AND PURPOSE: Glucagon-like peptide-1 (GLP) receptor agonists are promising therapeutic agents for the treatment of type II diabetes, but effects other than those on glucoregulation need assessing. Cardiovascular actions of bolus doses of the GLP receptor agonist exendin-4 have been reported, but to date the effects of continuous infusions have not been described. EXPERIMENTAL APPROACH: The regional haemodynamic effects and possible underlying mechanisms of 6 h infusions of exendin-4 were measured in conscious, chronically instrumented rats. KEY RESULTS: A 6 h infusion of exendin-4 (up to 6 pmol kg(-1) min(-1)) only modestly influenced blood pressure, but caused substantial, opposing, regionally selective vascular effects and tachycardia. A major involvement of beta-adrenoceptors in the vasodilator and cardiac effects was identified, with little or no direct contribution from alpha-adrenoceptors to the vasoconstriction seen. Under conditions where alpha- and beta-adrenoceptors were antagonized, or when ganglionic transmission was blocked, a marked vasoconstrictor effect of exendin-4 was revealed in the mesenteric and hindquarters vascular beds (about 50% fall in vascular conductances). No role for endogenous angiotensin II, vasopressin, endothelin, neuropeptide Y or prostanoids could be shown in these vasoconstrictor actions of exendin-4. CONCLUSIONS AND IMPLICATIONS: The results show not only an important involvement of the autonomic nervous system in the cardiovascular actions of exendin-4 infusion but also an underlying non-autonomically mediated vasoconstrictor action, the mechanism of which remains to be identified.     

Effects of nitric oxide synthase inhibition with or without cyclooxygenase-2 inhibition on resting haemodynamics and responses to exendin-4

BACKGROUND AND PURPOSE: Interactions between the NO system and the cyclooxygenase systems may be important in cardiovascular regulation. Here we measured the effects of acute cyclooxygenase-2 inhibition (with parecoxib), alone and in combination with NOS inhibition (with NG-nitro-L-arginine methyl ester (L-NAME)), on resting cardiovascular variables and on responses to the glucagon-like peptide 1 agonist, exendin-4, which causes regionally-selective vasoconstriction and vasodilatation. EXPERIMENTAL APPROACH: Rats were instrumented with flow probes and intravascular catheters to measure regional haemodynamics in the conscious, freely moving state. L-NAME was administered as a primed infusion 180 min after administration of parecoxib or vehicle, and exendin-4 was given 60 min after the onset of L-NAME infusion. KEY RESULTS: Parecoxib had no effect on resting cardiovascular variables or on responses to L-NAME. Exendin-4 caused a pressor response accompanied by tachycardia, mesenteric vasoconstriction and hindquarters vasodilatation. Parecoxib did not affect haemodynamic responses to exendin-4, but L-NAME inhibited its hindquarters vasodilator and tachycardic effects. When combined, L-NAME and parecoxib almost abolished the hindquarters vasodilatation while enhancing the pressor response. CONCLUSIONS AND IMPLICATIONS: Cyclooxygenase-2-derived products do not affect basal haemodynamic status in conscious normotensive rats, or influence the NO system acutely. The inhibitory effects of L-NAME on the hindquarters vasodilator and tachycardic effects of exendin-4 are consistent with a previous study that showed those events to be beta-adrenoceptor mediated. The additional effect of parecoxib on responses to exendin-4 in the presence of L-NAME, is consistent with other evidence for enhanced involvement of vasodilator prostanoids when NO production is reduced.     

Construction and performance of exendin-4-loaded chitosan–PLGA microspheres for enhancing implant osseointegration in type 2 diabetic rats

The updating and optimization of drug delivery systems is critical for better in vivo behaviors of drugs, as well as for improving impaired implant osseointegration in diabetes. Numerous studies have reported the benefits of exendin-4 on diabetic bone, with the potential to enhance osseointegration in diabetes. To construct an appropriate sustained-release system of exendin-4 targeting implant osseointegration in diabetes, this study fabricated exendin-4-loaded microspheres using poly(lactic-co-glycolic acid) (PLGA) and chitosan. The morphology, size, encapsulation efficiency, and drug release behavior of microspheres were investigated. The bioactivity of drug-loaded microspheres on cell proliferation and osteogenic differentiation of diabetic BMSCs was investigated to examine the pharmacologic action of exendin-4 loaded into chitosan–PLGA microspheres. Further, the influence of microspheres on osseointegration was evaluated using type 2 diabetes mellitus (T2DM) rat implant model. After 4 weeks, the samples were evaluated by radiological and histological analysis. The results of in vitro experiments showed that the prepared exendin-4-loaded chitosan–PLGA microspheres have good properties as a drug delivery system, and the chitosan could improve the encapsulation efficiency and drug release of PLGA microspheres. In addition, exendin-4-loaded microspheres could enhance the proliferation and osteogenic differentiation of diabetic BMSCs. The results of in vivo experiments showed the exendin-4-loaded microspheres significantly improved the impaired osseointegration and bone formation around implants in T2DM rats without affecting blood glucose levels. Thus, the local application of exendin-4-loaded chitosan–PLGA microspheres might be a promising therapeutic strategy for improving the efficacy of dental implants in T2DM individuals.     

The major determinant of exendin-4/glucagon-like peptide 1 differential affinity at the rat glucagon-like peptide 1 receptor N-terminal domain is a hydrogen bond from SER-32 of exendin-4

BACKGROUND AND PURPOSE

Exendin-4 (exenatide, Ex4) is a high-affinity peptide agonist at the glucagon-like peptide-1 receptor (GLP-1R), which has been approved as a treatment for type 2 diabetes. Part of the drug/hormone binding site was described in the crystal structures of both GLP-1 and Ex4 bound to the isolated N-terminal domain (NTD) of GLP-1R. However, these structures do not account for the large difference in affinity between GLP-1 and Ex4 at this isolated domain, or for the published role of the C-terminal extension of Ex4. Our aim was to clarify the pharmacology of GLP-1R in the context of these new structural data.

EXPERIMENTAL APPROACH

The affinities of GLP-1, Ex4 and various analogues were measured at human and rat GLP-1R (hGLP-1R and rGLP-1R, respectively) and various receptor variants. Molecular dynamics coupled with in silico mutagenesis were used to model and interpret the data.

KEY RESULTS

The membrane-tethered NTD of hGLP-1R displayed similar affinity for GLP-1 and Ex4 in sharp contrast to previous studies using the soluble isolated domain. The selectivity at rGLP-1R for Ex4(9–39) over Ex4(9–30) was due to Ser-32 in the ligand. While this selectivity was not observed at hGLP-1R, it was regained when Glu-68 of hGLP-1R was mutated to Asp.

CONCLUSIONS AND IMPLICATIONS

GLP-1 and Ex4 bind to the NTD of hGLP-1R with similar affinity. A hydrogen bond between Ser32 of Ex4 and Asp-68 of rGLP-1R, which is not formed with Glu-68 of hGLP-1R, is responsible for the improved affinity of Ex4 at the rat receptor.     

艾塞那肽促进葛根素改善高脂饮食糖尿病模型小鼠糖代谢作用的研究

前期研究发现葛根素通过上调胰岛β细胞GLP-1R(GLP-1 receptor)的表达保护β细胞,但葛根素综合降糖作用是否受到GLP-1R激活调控,尚未验证。本文采用GLP-1R激动剂艾塞那肽(exendin-4,Ex4)与GLP-1R拮抗剂毒蜥外泌肽9-39(exendin 9-39,Ex9-39),以高脂饮食(high-fat diet,HFD)诱导小鼠糖尿病模型,实验分为对照组、高脂组、高脂/葛根素组(300 mg·kg^-1·d^-1)、高脂/葛根素/Ex9-39组(Ex9-39:10 nmol·kg^-1·d^-1)、高脂/葛根素/Ex4组(Ex4:10 nmol·kg^-1·d^-1)。动物实验已获得南京中医药大学附属中西医结合医院动物伦理委员会批准(AEWC-025)。葛根素灌胃给药,Ex9-39与Ex4腹腔注射给药。给药10天,考察小鼠空腹血糖及口服葡萄糖耐量(oral glucose toler‐ance test,OGTT),测定血清胰岛素等指标,...