糖脂平对胰岛素抵抗大鼠骨骼肌IRS-1磷酸化及GLUT4分布的影响

目的:观察糖脂平对胰岛素抵抗大鼠骨骼肌IRS-1磷酸化及GLUT4分布的影响。方法:将24只清洁级SD大鼠随机分为对照组、模型组、中药组和西药组,采用高糖高脂饲料喂养方法造模成功后,分别给予生理盐水、糖脂平和二甲双胍灌胃,给药8周后,用Western Blot方法检测大鼠骨骼肌酪氨酸磷酸化IRS-1和磷酸化Akt的含量,用免疫荧光法观察大鼠骨骼肌GLUT4的分布情况。结果:实验末,与对照组比较,模型组大鼠骨骼肌酪氨酸磷酸化IRS-1和磷酸化Akt含量明显降低,中药组和西药组大鼠的骨骼肌酪氨酸磷酸化IRS-1和磷酸化Akt含量与模型组比较均明显升高,差异有统计学意义(P0.01),中药组和西药组的组间差异无统计学意义(P0.05)。对照组GLUT4分布于骨骼肌肌膜表面,模型组GLUT4膜分布明显减少,出现胞质分布,中药组和西药组GLUT4的膜分布较模型组明显改善。结论:糖脂平通过促进IRS-1的酪氨酸磷酸化,激活其下游PI3K,增加磷酸化Akt含量,进而使胞质内GLUT4膜转位增加,从而改善胰岛素抵抗。     

电针调控骨骼肌胰岛素受体底物-1磷酸化改善胰岛素抵抗的机制

目的:观察电针对2型糖尿病大鼠骨骼肌胰岛素受体底物-1(IRS-1)磷酸化水平的影响,从而探讨电针治疗2型糖尿病的可能机制.方法:采用2型糖尿病肥胖大鼠作为研究对象.将成模后的14只ZDF大鼠随机分为模型组、电针组,每组7只;另将7只ZL大鼠设为空白组.干预4周,检测空腹血糖(FBG),并以Western Blot法检...     

葛根素对大鼠胰岛素刺激下骨骼肌细胞膜GLUT4蛋白含量的影响

目的 :了解葛根素对糖尿病胰岛素抵抗状态是否有改善作用 ,并探讨这种作用是否通过影响大鼠骨骼肌细胞膜GLUT4蛋白含量而实现。方法 :制备胰岛素抵抗大鼠模型。将动物分为 3组 :正常对照组 ;胰岛素抵抗模型组 ;胰岛素抵抗模型 +葛根素治疗组。第 3组大鼠腹腔注射葛根素 100mg·kg^-1·d^-1,治疗 4周。用Westernblot方法检测骨骼肌细胞膜表面GLUT4蛋白表达。结果 :胰岛素抵抗模型组大鼠骨骼肌细胞膜GLUT4蛋白表达显著减少 ,与正常对照组相比 ,减少约 31% ;用葛根素注射液治疗后 ,细胞膜GLUT4蛋白表达明显上调 ,约 1.18倍。结论 :葛根素可能通过降糖、改善高胰岛素血症 ,从而影响细胞内胰岛素信号传导 ,使GLUT4转位至细胞膜增加 ,其在膜上的含量也增加 ,发挥快速转运葡萄糖的作用。     

黄芪多糖对2型糖尿病大鼠骨骼肌组织GLUT4表达的影响

目的探讨研究黄芪多糖(APS)对2型糖尿病大鼠的作用及对骨骼肌组织GLUT4表达的影响。方法SD大鼠随机分为:正常对照组、黄芪多糖对照组(APS组)、2型糖尿病组(TIIDM组)和2型糖尿病黄芪多糖治疗组(TIIDM APS组),5周后测血糖、血清胰岛素和GLUT4的水平。结果TIIDM组和TIIDM APS组血糖均高于对照组(P<0.01),TI-IDM APS组血糖低于TIIDM组(P<0.01);各组间血胰岛素水平差别无显著性(P>0.05);TIIDM组骨骼肌组织GLUT4的表达低于对照组和TIIDM APS组(P<0.01)。结论APS可降低TIIDM大鼠血糖水平,其机制与提高糖尿病大鼠骨骼肌中GLUT4表达有关。     

妊娠糖尿病患者网IRS-1与GLUT4的表达及其与胰岛素抵抗关系的研究

妊娠期糖尿病指妊娠前无糖尿病亦无糖耐量减低的妇女,在妊娠期间首次发生或发现的葡萄糖耐量异常.     

原钒酸钠对2型糖尿病大鼠骨骼肌GLUT4mRNA表达的影响

 目的 观察原钒酸钠(sodium orthovanadate)对2型糖尿病大鼠骨骼肌葡萄糖转运蛋白4(GLUT4)mRNA表达的影响。方法 用高脂饲料灌胃正常大鼠10 d,引起肥胖,再用四氧嘧啶(120mg·kg^-1)腹腔注射,建立2型糖尿病大鼠模型。筛选空腹血糖值大于16.7 mmol·L^-1的大鼠,随机分成5组:原钒酸钠大剂量组(9 mg·kg^-1·d^-1)、原钒酸钠中剂量组(3 mg·kg^-1·d^-1)、原钒酸钠小剂量组(1 mg·kg^-1·d^-1)、糖尿病模型组、苯乙双胍组(75 mg·kg^-1·d^-1)。连续用药7d,用快速血糖仪测空腹血糖值。用胰岛素放免试剂盒测血清胰岛素值。用骨骼肌GLUT4原位杂交试剂盒检测骨骼肌GLUT4 mRNA的表达。结果①2型糖尿病大鼠经原钒酸钠灌胃给药后,空腹血糖值与模型组相比有明显的降低(P<0.05);②用药组大鼠血清胰岛素值与模型组相比无显著差异;③用药组大鼠的骨骼肌GLUT4 mRNA表达量与模型组相比均有明显增多。结论 原钒酸钠对2型糖尿病大鼠有明显的降糖作用,对血清胰岛素的分泌无明显影响,对2型糖尿病大鼠骨骼肌GLUT4 mRNA的表达有促进作用。     

Coriolus versicolor aqueous extract ameliorates insulin resistance with PI3K/Akt and p38 MAPK signaling pathways involved in diabetic skeletal muscle

Patients with type 2 diabetes mellitus (T2DM) are usually with poor immunity and easier to suffer from cancer and microbial infections. Herein, we report an efficient anti‐diabetic medicinal mushroom, Coriolus versicolor (CV). This study aimed to investigate the anti‐diabetic and anti‐insulin‐resistance effects of CV aqueous extract in myoblasts (L6 cells) and skeletal muscle of T2DM rat. Our results showed that CV extract treatment significantly reduced blood glucose levels of T2DM rats, whereas CV extract increased glucose consumption in insulin resistant L6 cells. Besides, the translocation and expression of glucose transporter 4 were enhanced by CV extract, which indicated that CV extract was effective in diabetic skeletal muscle. Moreover, CV extract treatments resulted in remarkable anti‐insulin‐resistance effects, which was reflected by the change of gene and protein expression levels in PI3K/Akt and p38 MAPK pathways. PI3K inhibitor, LY29004, and p38 MAPK inhibitor, SB203580 confirmed it further. In conclusion, our results demonstrated that the CV extract exhibited anti‐diabetic and anti‐insulin‐resistance effects in diabetic skeletal muscle, and the effects were mediated by PI3K/Akt and p38 MAPK pathways. These findings are remarkable when considering the use of commercially available CV by diabetic patients who also suffer from cancer or microbial infections.     

Momordica charantia extract on insulin resistance and the skeletal muscle GLUT4 protein in fructose-fed rats

Aim of the study

We investigated the preventive effect of Momordica charantia Linn. (Cucurbitaceae) fruit, commonly known as bitter melon, on hyperglycemia and insulin resistance in rats fed with a fructose-enriched diet.

Materials and methods

First, rats were divided randomly into two groups: the control group was fed with control diet, whereas the experimental group was fed with a 60% high-fructose diet for 8 weeks. After the first 6 weeks, the fructose-treated rats were further subdivided into six groups and were orally fed with or without Momordica charantia L. or rosiglitazone (ROS) for 2 weeks while rats were still on fructose diet.

Results

We demonstrated that bitter melon was effective in ameliorating the fructose diet-induced hyperglycemia, hyperleptinemia, hyperinsulinemia, and hypertriglyceridemia as well as in decreasing the levels of free fatty acid (FFA) (P < 0.001, P < 0.05, P < 0.05, P < 0.05, P < 0.05, respectively). Bitter melon reversed fructose diet-induced hypoadiponectinemia (P < 0.05), which provides a therapeutic advantage to insulin resistance in improving insulin sensitivity. Additionally, bitter melon decreased the weights of epididymal (P < 0.05) and retroperitoneal white adipose tissue (WAT) (P < 0.05). Bitter melon increased the expression of peroxisome proliferator-activated receptor γ (PPARγ) in white adipose tissue (WAT). Conversely, bitter melon decreased the expression of leptin in WAT. Furthermore, we demonstrate that bitter melon significantly increases the mRNA expression and protein of glucose transporter 4 (GLUT4) in skeletal muscle.

Conclusions

This study demonstrates, for the first time, the beneficial effects of two different extracts of bitter melon on insulin resistance in rats fed a high-fructose diet thereby producing evidence of the role of changes in expression of PPARγ and GLUT4.     

仙鹤草对2型糖尿病大鼠胰岛素抵抗及炎性因子的干预作用

目的观察仙鹤草提取物对2型糖尿病大鼠血糖、血脂、胰岛素抵抗及血清中炎性因子的影响。方法采用高脂饲料喂养加腹腔注射小剂量链脲佐菌素STZ的方法制备2型糖尿病动物模型,随机分为4组（n=9）：模型组、吡格列酮组、仙鹤草高剂量组、仙鹤草低剂量组。灌胃给药4周后取血检测各组大鼠空腹血糖（FBG）、甘油三酯（TG）、总胆固醇（CHOL）、高密度脂蛋白（HDL-C）、低密度脂蛋白（LDL-C）,采用放射免疫法测定空腹血清胰岛素（Fins）、肿瘤坏死因子α（TNF-α）、C反应蛋白（CRP）,并根据Fins,FBG计算胰岛素抵抗指数（HOMA-IR）。结果仙鹤草高剂量可显著降低大鼠FBG,FINS,HOMA-IR;可降低甘油三酯,升高高密度脂蛋白;降低血清中炎性因子TNF-α和CRP含量。结论仙鹤草提取物对2型糖尿病大鼠具有降糖调脂的治疗作用,可缓解2型糖尿病胰岛素抵抗,并推测可能与降低血清炎性因子含量有关。     

Morus alba leaf extract stimulates 5′-AMP-activated protein kinase in isolated rat skeletal muscle

Aim of the study

Morus alba (mulberry) leaf is a natural therapeutic agent that has been shown to have an antidiabetic effect. We explored the possibility that 5′-AMP-activated protein kinase (AMPK) is involved in metabolic enhancement by the Morus alba leaf.

Materials and methods

Isolated rat epitrochlearis muscle was incubated in a buffer containing Morus alba leaf hot water extract (MLE) and the AMPK activation and related events were examined.

Results

In response to MLE treatment, the Thr¹⁷² phosphorylation of the catalytic α subunit of AMPK, an essential step for full kinase activation increased in a dose- and time-dependent manner. Ser⁷⁹ phosphorylation of acetyl CoA carboxylase, an intracellular substrate of AMPK, increased similarly. Analysis of isoform-specific AMPK activity revealed that MLE activated both the α1 and α2 isoforms of the catalytic subunit. This increase in enzyme activity was associated with an increased rate of 3-O-methyl-d-glucose transport in the absence of insulin and with phosphorylation of AS160, a signaling intermediary leading to glucose transporter 4 translocation. The intracellular energy status, estimated from the ATP and phosphocreatine concentrations, was not affected by MLE.

Conclusion

MLE stimulates skeletal muscle AMPK activity acutely without changing the intracellular energy status.     

Hesperidin ameliorates insulin resistance by regulating the IRS1‐GLUT2 pathway via TLR4 in HepG2 cells

The aim of this study was to evaluate the effect and mechanism of hesperidin (HES) on insulin resistance (IR) in the human hepatocellular carcinoma cell line (HepG2 cells). HepG2 cells were induced with lipopolysaccharide (LPS) as a model of IR and treated with HES at three dosages. Next, the levels of interleukin‐6 (IL‐6) and tumor necrosis factor‐α (TNF‐α), the glucose content, and glucose uptake were evaluated by enzyme‐linked immunosorbent assay, glucose oxidase‐peroxidase method (GOD‐POD), or (2‐(N‐(7‐nitrobenz‐2‐oxa‐1, 3‐diazol‐4‐yl)amino)‐2‐deoxyglucose) (2‐NBDG). Moreover, the protein expression of toll‐like receptors 4 (TLR4), insulin receptor substrate 1 (IRS1), nuclear factor kappa B (NF‐κB), and glucose transporter 2 (GLUT2) in HepG2 cells treated with HES were assessed via western blotting analysis. In addition, GLUT2 protein expression exposed to HES was detected following treatment with TLR4 inhibitor (HTA125). Our results demonstrated that HES decreased the levels of TNF‐α and IL‐6, attenuated the glucose content in culture medium and increased glucose uptake in insulin‐resistant HepG2 cells in vitro. Moreover, HES upregulated the expression of IRS1 and GLUT2 protein and downregulated the protein expression of TLR4 and NF‐κB in insulin‐resistant HepG2 cells. The expression of GLUT2 protein had no significant changes when treated with HES after blockade of TLR4. HES attenuated IR in LPS‐inducedinsulin‐resistant HepG2 cells. Therefore, regulating the IRS1‐GLUT2 pathway via TLR4 represents a potential mechanism of HES on IR in HepG2 cells.     

桑叶提取物调控IRS-1/PI3K/GLUT4通路影响2型糖尿病胰岛素抵抗机制研究

目的:提取桑叶中的黄酮类及多酚类物质,观察其对2型糖尿病(T2DM)模型大鼠降血糖及改善胰岛素抵抗(IR的作用,并探讨其分子机制。方法:取雄性SD大鼠,分为正常组、模型组、二甲双胍组、桑叶提取物组,除正常组以外建立T2DM模型,灌胃干预4周,观察药物对模型大鼠一般情况、生化指标、骨骼肌病理等的影响。测定胰岛素受体底物-1 (IRS-1)、磷脂酰肌醇3-激酶(PI3K)中的p85α、葡萄糖转运体-4 (GLUT4)在骨骼肌组织中的信使核糖核酸(mRNA)及蛋白表达水平。结果:与正常组比较,模型组空腹血糖(FBG)、IR稳态模型指数(HOMA-IR)、血清胰岛素、总胆固醇、甘油三酯、低密度脂蛋白水平升高(P<0.05);IRS-1、PI3K p85α、GLUT4的mRNA及蛋白表达明显下降(P<0.05)。与模型组比较,桑叶提取物组FBG、HOMA-IR、总胆固醇、甘油三酯、低密度脂蛋白水平下降(P<0.05);IRS-1、PI3K p85α、GLUT4的mRNA及蛋白表达明显升高(P<0.05);二甲双胍组FBG有所下降,但差异无统计学意义,血清胰岛素及HOMA-...     

Cyclocarya paliurus extract modulates adipokine expression and improves insulin sensitivity by inhibition of inflammation in mice

Ethnopharmacological relevance

Cyclocarya paliurus Batal., a Chinese native plant, is the sole species in its genus and its leaves have been widely used as a remedy for diabetes in traditional folk medicine. The study was undertaken to evaluate the effects of Cyclocarya paliurus leaves extracts (CPE) on adipokine expression and insulin sensitivity in mice.

Materials and methods

Mice were stimulated with conditioned medium (prepared from activated macrophages, Mac-CM) to induce adipose dysfunction and insulin resistance. Then mice were treated with CPE (100, 200 and 500 mg/kg, ig.) or metformin (200 mg/kg, ig.), followed by glucose and insulin intolerance, adipokine expression, phosphorylation of insulin receptor substrate (IRS-1) and glucose consumption measurement.

Results

CPE, as well as metformin effectively promoted glucose disposal in oral glucose tolerance test in normal mice. Mac-CM challenge induced glucose and insulin intolerance, but CPE reversed these alternations with increased glycogen content in muscle and liver, well demonstrating its beneficial effects on glucose homeostasis. RT-qPCR analysis showed that CPE inhibited TNF-a, IL-6, MCP-1 and resistin overexpression and effectively enhanced adiponectin expression in adipose tissue when mice were exposed to Mac-CM stimulation. Inflammation impaired insulin signaling in muscle, whereas CPE inhibited inflammation-induced serine phosphorylation of IRS-1 and effectively restored the phosphorylation of both IRS-1 at tyrosine residues and downstream Akt phosphorylation in response to insulin. Moreover, independently of insulin, CPE promoted glucose consumption in adipocytes under normal and inflammatory conditions.

Conclusion

Above-mentioned results demonstrated that CPE beneficially regulated adipokines expression and ameliorated insulin resistance through inhibition of inflammation in mice.     

黄金胶囊改善糖尿病大鼠胰岛素抵抗与PI-3K,GLUT4蛋白的表达

目的:研究黄金胶囊对糖尿病(DM)大鼠磷脂酰肌醇3激酶(PI-3K),葡萄糖转运因子4(GLUT4)在肝脏及骨骼肌组织中的蛋白表达,并探讨其改善大鼠血糖的可能机制。方法:SPF级雄性Wistar大鼠65只,血糖在4.77~7.77 mmol·L~(-1)的大鼠入选,入选大鼠60只,正常组12只外,其余大鼠采用高脂饲料喂养联合小剂量链脲佐菌素ip的方法,建立DM大鼠模型。将造模成功大鼠随机分为黄金胶囊组(2.025 g·kg~(-1)),罗格列酮组(0.36 mg·kg~(-1)),模型组,继续高脂饲料喂养,并予以相应药物ig治疗10周,其中模型组与正常组均予以生理盐水ig,观察大鼠一般状态,体重及摄食量,干预10周后,予10%水合氯醛麻醉大鼠,检测大鼠空腹血糖(FBG),空腹胰岛素(FINS)及胰岛素敏感指数(ISI)。采用苏木素-伊红(HE)检测各组大鼠肝脏、骨骼肌组织的病理改变及免疫组化检测PI-3K和GLUT4蛋白的表达。结果:与正常组比较,模型组DM大鼠FBG,FINS水平明显升高,ISI水平明显降低,肝脏及骨骼肌组织中PI-3K,GLUT4蛋白表达明显降低(P0.05),病理学检测发现大鼠肝脏、骨骼肌组织的病变较为明显;与模型组比较,药物干预后,黄金胶囊组与罗格列酮组均可降低DM大鼠的FBG,FINS水平,提高ISI水平,明显升高肝脏及骨骼肌组织中PI-3K,GLUT4蛋白表达(P0.05),大鼠肝脏、骨骼肌组织的病变明显改善。结论:黄金胶囊提高胰岛素敏感性的作用,与激活肝脏及骨骼肌组织胰岛素信号传导通路中PI-3K和GLUT4的蛋白表达有关。     

兰连糖毒清汤对糖尿病小鼠胰岛素抵抗及NALP3炎症体的影响

目的:探讨兰连糖毒清汤对糖尿病小鼠胰岛素抵抗的改善作用,并基于核苷酸结合寡聚化结构域样受体3(NALP3)炎症体探讨其作用机制。方法:将40只6周龄雄性db/db小鼠随机分为兰连糖毒清低剂量组、兰连糖毒清高剂量组、模型组和罗格列酮组,同时设立正常db/dm小鼠10只为空白组。干预8周后,检测各组小鼠口服葡萄糖耐量曲线下面积(AUC),稳定模型测定小鼠胰岛素抵抗指数(HOMA-IR)及定量胰岛素敏感性检查指数(QUICKI),ELISA法检测血清肿瘤坏死因子-α(TNF-α)、白介素-6(IL-6)、白介素-1β(IL-1β)、白介素-18(IL-18)水平,HE染色法观察小鼠肝脏组织,免疫组化检测小鼠胰腺组织NALP3的表达,Western blot及RT-qPCR检测小鼠骨骼肌组织NALP3蛋白及mRNA表达。结果:兰连糖毒清汤可降低小鼠AUC、空腹胰岛素(FINS)、HOMA-IR及血清TNF-α、IL-6、IL-1β、IL-18水平,增加QUICKI指数(均P<0.05)。兰连糖毒清汤可降低小鼠骨骼肌组织NALP3蛋白及mRNA表达,降低胰腺组织NALP3蛋白表达(均P&l...     

MDG-1, a polysaccharide from Ophiopogon japonicus exerts hypoglycemic effects through the PI3K/Akt pathway in a diabetic KKAy mouse model

Ethnopharmacological relevance

Ophiopogon japonicus is a traditional Chinese medicine that might be helpful for the treatment of type 2 diabetes. Recent studies have confirmed its beneficial properties, but not the mechanism of action.

Aim of study

In this study, we examined the effects of a water-soluble β-d-fructan (MDG-1) from O. japonicus on type 2 diabetes through the PI3K/Akt pathway in a diabetic KKAy mouse model.

Materials and methods

MDG-1 was extracted from the tube root of O. japonicus and purified as described previously ( Xu et al., 2005). The KKAy mice were gavaged once daily with either distilled water, MDG-1or rosiglitazonefor 8 weeks. Blood glucose levels were tested regularly for the fed and fasted mice. In order to evaluate the effect of MDG-1 on disease progression, the proteins of InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 were detected by Western blotting and serum TG, TC, HDL-C, LDL-C were also dertermined.

Results

MDG-1 reduced the hyperglycemia, hyperinsulinemia and hyperlipidemia in the KKAy mice. The oral glucose tolerance test (OGTT) and the level of insulin in the serun showed that insulin resistance in KKAy mice was ameliorated after MDG-1 treated. After 8 weeks treatment with 300 mg/kg MDG-1, the content of triglycerides (TG) and low density lipoprotein cholesterol (LDL-C) the serum decreased significantly. Meanwhile high density lipoprotein cholesterol (HDL-C) content increased notably. MDG-1 did not have any effect on total cholesterol (TC) content in the serum, whereas rosiglitazone significantly decreased the TC content. In addition, MDG-1 upregulates the phosphoinositide 3-kinase p85 subunit, Akt, insulin receptor (InsR), insulin receptor substrate-1 (IRS-1) and Glut-4 expression, but downregulates glycogen synthase kinase 3β expression.

Conclusions

These data indicate that MDG-1 has remarkable anti-diabetic activity through the InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 signaling pathway. We believe that MDG-1 is a promising anti-diabetic compound that will be helpful for the treatment of T2DM.     

津力达对高脂诱导的胰岛素抵抗ApoE-/-小鼠骨骼肌脂质转运酶类的表达变化

目的:探究津力达对高脂诱导的胰岛素抵抗Apo E-/-小鼠骨骼肌脂质转运酶类相关基因的表达变化。方法:8只雄性C57BL/6J小鼠设为正常组(NF);40只雄性Apo E-/-小鼠喂养16周后分为模型组(HF)、罗格列酮组(LGLT)、津力达低剂量组(JLDL)、津力达中剂量组(JLDM)、津力达高剂量组(JLDH),开始灌胃给药,连续8周。采用组织游离脂肪酸、BCA蛋白浓度法测定骨骼肌FFA含量;实时荧光定量反转录PCR(RT-PCR)和蛋白质印迹法(Western blot)测定小鼠骨骼肌脂肪酸转位酶(FAT/CD36)、肉毒碱棕榈酰基转移酶1(CPT1)、过氧化物酶体增殖物激活受体α(PPARα)mRNA和蛋白表达。结果:津力达能够不同程度降低小鼠的空腹血糖(FBG)、胆固醇(TC)、甘油三酯(TG)和游离脂肪酸(FFA);下调空腹胰岛素(FIns)水平,提高胰岛素敏感指数(ISI);津力达能够不同程度的上调小鼠CPT1,PPARαmRNA和蛋白表达,下调FAT/CD36的mRNA和蛋白水平。结论:津力达能够通过调节骨骼肌脂质转运酶类的表达变化,改善高脂诱导的Apo E-/-小鼠的胰岛素抵抗。     

Populus balsamifera L. (Salicaceae) mitigates the development of obesity and improves insulin sensitivity in a diet-induced obese mouse model

Ethnobotanical relevance

: In previous in vitro bioassay studies, Populus balsamifera L. (Salicaceae), a medicinal plant ethnobotanically identified from the traditional pharmacopoeia of the Cree of Eeyou Istchee (Eastern James Bay area of Canada), exhibited a strong anti-obesity potential by potently inhibiting adipogenesis in 3T3-L1 adipocytes. The aim of the study is to evaluate the effectiveness of this plant extract in mitigating the development of obesity and the metabolic syndrome in diet-induced obese (DIO) C57BL/6 mice.

Materials and methods

Mice were subjected for eight weeks to a standard diet (CHOW), a high fat diet (HFD; DIO group), or HFD to which Populus balsamifera was incorporated at 125 and 250 mg/kg.

Results

The results showed that Populus balsamifera decreased in a dose-dependent manner the weight gain of whole body, retroperitoneal fat pad and liver as compared to DIO controls and reduced the severity of hepatic macrovesicular steatosis and triglyceride accumulation. This plant extract also decreased glycemia in the second half of the feeding period and improved insulin sensitivity by diminishing insulin levels and the leptin/adiponectin ratio, as well as augmenting adiponectin levels. These effects were associated with slightly but significantly reduced food intake with 250 mg/kg Populus balsamifera as well as with an increase in energy expenditure (increase in skin temperature and increased expression of uncoupling protein-1; UCP-1). Data also suggest other mechanisms, such as inhibition of adipocyte differentiation, decrease of hepatic inflammatory state and potential increase in hepatic fatty acid oxidation.

Conclusion

Taken together, these results confirm the potential of Populus balsamifera as a culturally adapted therapeutic approach for the care and treatment of obesity and diabetes among the Cree.     

A refined-JinQi-JiangTang tablet ameliorates prediabetes by reducing insulin resistance and improving beta cell function in mice

Ethnopharmacological relevance

Refined-JQ (JQ-R) is a mixture of refined extracts from three major herbal components of JinQi-JiangTang tablet: Coptis chinensis (Ranunculaceae), Astragalus membranaceus (Leguminosae), and Lonicera japonica (Caprifoliaceae). Our previous studies have indicated that JQ-R could decrease fasting blood glucose levels in diabetic mice and insulin resistance mice. Investigating the hypoglycemic effect of JQ-R on prediabetes has practical application value for preventing or delaying insulin resistance, impaired glucose tolerance and possibly the development of clinical diabetes.

Materials and methods

The anti-diabetic potential of JQ-R was investigated using a high fat-diet (HFD)-induced obesity mouse model. C57BL/6J mice (HFD-C57 mice) were fed with high-fat diet for 4 months. HFD-C57 mice were treated with either JQ-R (administered intragastrically once daily for 4 weeks) or metformin (as positive control), and the effects of JQ-R on body weight, blood lipids, glucose metabolism, insulin sensitivity, and beta cell function were monitored.

Results

The body weight, serum cholesterol, and the Homeostasis Model Assessment ratio (insulin resistance index) were significantly reduced in JQ-R or metformin-treated mice, and the glucose tolerance was enhanced and insulin response was improved simultaneously. Moreover, both JQ-R and metformin could activate liver glycogen syntheses even under a relatively high glucose loading. Although glyconeogenesis was inhibited in the metformin treated mice, it was not observed in JQ-R treated mice. Similar to metformin, JQ-R could also improve the glucose infusion rate (GIR) in hyperglycemic clamp test. JQ-R was also shown to increase the levels of phosphorylated AMPKα and phosphorylated acetyl CoA carboxylase (ACC), similar to metformin.

Conclusion

JQ-R could reduce HFD-induced insulin resistance by regulating glucose and lipid metabolism, increasing insulin sensitivity through activating the AMPK signaling pathway, and subsequently improving β cell function. Therefore, JQ-R may offer an alternative in treating disorders associated with insulin resistance, such as prediabetes and T2DM.