科罗索酸对HepG2细胞糖消耗以及细胞内糖原的影响

目的：研究糖原磷酸化酶抑制剂科罗索酸对HepG2细胞的葡萄糖消耗以及对正常和应激状态下细胞内糖原含量的影响。方法：不同浓度的科罗索酸与HepG2细胞共同孵育24小时后,用葡萄糖氧化酶法测定单位细胞的糖消耗量,并分别测定正常和应激状态下细胞内糖原的含量。结果：1和10μmol.L-1的科罗索酸能显著增加HepG2细胞的单位细胞糖消耗量,提高HepG2细胞内的糖原含量（P〈0.05,P〈0.01）。HepG2细胞经去甲肾上腺素处理后,细胞内糖原降解明显增加1,0μmol.L-1的科罗索酸能显著升高细胞内糖原含量水平（P〈0.05）。结论：科罗索酸能够增加细胞的葡萄糖消耗,抑制糖原过度降解。     

五环三萜抑制A549细胞生长与促进糖原累积作用的相关性研究

目的:研究五环三萜化合物(齐墩果酸和山楂酸)对人肺腺癌A549细胞的生长是否有抑制作用并对其可能的作用机制即抑制糖原磷酸化酶进行探讨。方法:用MTT法测定不同浓度的化合物对A549细胞生长的抑制作用;通过测定细胞中的糖原含量的变化证实化合物抑制了细胞中糖原磷酸化酶的活性。结果:MTT法测得化合物对A549细胞生长具有抑制作用。同时,测得齐墩果酸和山楂酸对A549细胞的糖原磷酸化酶具有抑制活性,其IC50分别是5.98和4.01μmol.L-1。进一步经化合物处理后的细胞内糖原含量呈现剂量依赖性增加。结论:齐墩果酸和山楂酸具有抑制A549细胞生长的作用,其作用可能是通过抑制细胞内的糖原磷酸化酶活性而实现的。     

褪黑素通过Akt抑制胰岛素抵抗HepG2细胞糖内生

目的探讨褪黑素(melatonin,MLT)对胰岛素抵抗(insulin resistance,IR)肝HepG2细胞葡萄糖内生的影响及其机制。方法HepG2 IR细胞模型采用高糖(25 mmol·L-1)联合高胰岛素(1μmol·L-1)培养诱导建立。MLT(10 nmol·L-1)处理模型细胞6 h后检测糖消耗及糖原含量,GSK-3β、Akt和FoxO1蛋白磷酸化水平检测采用Western blot,免疫荧光法检测FoxO1蛋白核外排情况。结果IR HepG2细胞经MLT处理后,葡萄糖的摄取和糖原合成增加,p-GSK-3β和p-Akt蛋白水平分别增高约66%和48%,FoxO1磷酸化水平明显提高且细胞质含量增加。结论MLT可能通过Akt/GSK-3β及Akt/FoxO1信号通路促进胰岛素抵抗HepG2细胞的糖原合成和抑制糖异生,从而改善糖代谢。     

胰岛素抵抗HepG2细胞模型建立的正交实验研究

目的探索联合应用胰岛素(INS)、棕榈酸(PA)和高糖建立HepG2细胞胰岛素抵抗(IR)模型的最佳实验方法。方法单因素考察INS、PA浓度及孵育时间对HepG2细胞增殖活性的影响;正交实验确定建立HepG2细胞IR模型的最佳条件。蒽酮法检测细胞糖原含量,油红O染色观察细胞形态变化。结果影响HepG2细胞葡萄糖消耗的主次因素顺序为:孵育时间>PA>INS,10 μmol·L-~1 PA联合1.0 μmol·L-~1 INS的高糖培养基孵育HepG2细胞48 h,葡萄糖消耗减少了22.36%。模型组细胞糖原合成较对照组显著减少,细胞脂肪颗粒明显增加。模型细胞IR作用可持续存在48 h,但24 h时作用最强。结论高糖培养基联合小剂量PA和INS,较长时间作用于HepG2细胞建立的IR模型,稳定可靠,重复性好,接近人体IR的病理生理状态,为防治IR药物筛选及发病机制研究奠定基础。     

人参多肽降血糖作用

人参多肽按50,100和200mg/kg的剂量给大鼠一次ⅳ或小鼠多次sc给药,能降低正常血糖和肝糖原,但对总血脂无明显影响。同时表明,对肾上腺、四氧密啶及葡萄糖所引起的高血糖均有抑制作用,并能增强肾上腺素对肝糖原的分解。     

新型糖原磷酸化酶抑制剂-山楂酸内皮素信号通路的过度激活而改善心肌纤维化

目的研究糖原磷酸化酶抑制剂-山楂酸对缺血性脑损伤的保护作用,初步探讨糖原磷酸化酶抑制剂的脑缺血保护机制.方法采用合并迷走神经结扎双侧颈总动脉造成小鼠急性不完全性脑缺血-再灌注模型,测定脑组织匀浆乳酸含量、相关生化指标以及肝糖原含量.结果山楂酸灌胃给药以后能降低脑组织乳酸、丙二醛含量,提高超氧化物歧化酶、乳酸脱氢酶活力,还能对抗缺血期间的肝糖原降解.结论山楂酸对缺血性脑损伤具有一定保护作用,其抗脑缺血作用至少是与通过部分抑制糖酵解并进而减轻代谢性酸中毒有关.     

新型糖原磷酸化酶抑制剂-山楂酸对小鼠脑缺血-再灌注的保护作用研究

目的：研究糖原磷酸化酶抑制剂-山楂酸对缺血性脑损伤的保护作用,初步探讨糖原磷酸化酶抑制剂的脑缺血保护机制。方法：采用合并迷走神经结扎双侧颈总动脉造成小鼠急性不完全性脑缺血-再灌注模型,测定脑组织匀浆乳酸含量、相关生化指标以及肝糖原含量。结果：山楂酸灌胃给药以后能降低脑组织乳酸、丙二醛含量,提高超氧化物歧化酶、乳酸脱氢酶活力,还能对抗缺血期间的肝糖原降解。结论：山楂酸对缺血性脑损伤具有一定保护作用,其抗脑缺血作用至少是与通过部分抑制糖酵解并进而减轻代谢性酸中毒有关。     

白子菜水提液对胰岛素抵抗HepG2细胞关键酶活性的影响

摘要 目的 探讨白子菜水提液对胰岛素抵抗HepG2细胞关键酶活性的影响。方法采用葡萄糖临床检测试剂盒、肝糖原测定试剂盒检测白子菜水提液对胰岛素抵抗HepG2细胞葡萄糖消耗和HepG2细胞的糖原含量的影响;采用葡萄糖 6 磷酸脱氢酶耦联比色法、乳酸脱氢酶耦联比色法及钼酸铵定磷法测定葡萄糖激酶（GK）、磷酸烯醇式丙酮酸羧激酶（PEPCK）和葡萄糖 6 磷酸酶（G 6 Pase）的活性。结果白子菜水提液能够促进胰岛素抵抗HepG2细胞的葡萄糖消耗,使G 6 Pase及PEPCK活性分别降低71.41%,82.14%,使GK活性和糖原含量分别提高28.77%,96.73%。结论白子菜水提液可降低胰岛素抵抗HepG2细胞G 6 Pase和PEPCK的活性,抑制糖异生作用,从而减少细胞内源性葡萄糖的产生。此外,白子菜水提液还提高GK活性,加快糖酵解的进行,增加糖原含量,减轻HepG2细胞的胰岛素抵抗状态。     

人参多肽降血糖机制的研究

人参多肽(GP)无论sc或iv(50～200 mg/kg)对大鼠和小鼠均有明显的降低血糖和肝糖原作用,肾上腺切除并未影响其降低肝糖原作用。酚妥拉明和普萘洛尔分別抑制GP对大鼠肝糖原和血糖的影响。GP在降低血糖和肝糖原时,可使小鼠肝组织cAMP增加。由于血及肝组织LDH受到抑制,血乳酸含量降低,而血丙酮酸含量升高。实验证明,GP降血糖作用除了其促进糖原分解或抑制乳酸合成肝糖原作用外,主要由于其刺激了SDH和CCD的活性使糖的有氧氧化作用增强的缘故。     

HepG2细胞胰岛素抵抗模型的建立及在筛选桑叶有效部位中的应用

目的体外建立HepG2细胞胰岛素抵抗模型,并用于筛选桑叶防治胰岛素抵抗活性的有效部位。方法采用高浓度胰岛素诱导HepG2细胞建立肝胰岛素抵抗模型,研究桑叶有效部位对胰岛素抵抗模型细胞葡萄糖消耗的影响。结果将HepG2细胞置于10 μg·mL－1胰岛素中48 h,HepG2细胞对胰岛素的抵抗作用最明显,其特性可维持48 h。桑叶水提部位能促进HepG2胰岛素抵抗模型的葡萄糖消耗。结论高胰岛素诱导培养法可以复制出稳定可靠的肝胰岛素抵抗细胞模型。桑叶水提物、多糖、黄酮均可以促进葡萄糖的吸收。     

Comparison of the acute toxicity of endothal and cantharidic acid on mouse liver in vivo

Endothal and cantharidic acid were administered intraperitoneally to mice at 75 and 10 mg/kg, respectively, to compare their acute toxicity on liver tissue in vivo. Within 45 min both treatments caused extreme liver enlargement and congestion. Hepatic glycogenolysis was increased as evidenced by elevations in blood glucose and hepatic glycogen phosphorylase levels and by corresponding reductions in hepatic glycogen content and glycogen synthase activity. Endothal decreased hepatic ATP concentrations, although neither compound altered mitochondrial Mg2+-ATPase activity. Microsomal Mg2+-ATPase levels, however, were reduced by both treatments. There were no indications that reactive intermediates were involved in the toxicity of either compound. The results show that endothal and cantharidic acid act directly and cause similar biochemical changes in mouse liver in vivo.     

Effect of praziquantel on some aspects of carbohydrate metabolism in mice infected with Schistosoma mansoni

Schistosoma mansoni infection in mice resulted in a marked decrease in blood glucose and liver glycogen accompanied by a significant increase in hepatic glucose-6-phosphatase (G-6-Pase) activity. Moreover, the results indicated that infection produced a significant increase in blood pyruvate and hepatic glucose-6-phosphate dehydrogenase (G-6-PD) activity with a significant decrease in blood lactate. Infected mice were treated with praziquantel which was given at two doses of 500 mg/kg body wt on two consecutive days. Seven and 14 days respectively after drug administration, such treatment caused a marked improvement in the previous aspects of carbohydrate metabolism. This is indicated by the tendency of the blood glucose of infected mice to be restored, the marked increase in their liver glycogen content, the normalization of their blood lactate and pyruvate as well as by the marked decrease of their hepatic G-6-Pase activity and the progressive increase in their hepatic G-6-PD activity. Praziquantel given to normal mice moderately affected the blood glucose and the previously mentioned hepatic enzymes. However, the drug markedly increased the liver glycogen content of normal mice and failed to elicit any change in their blood pyruvate and lactate. Possible explanations of these findings are discussed.     

鲨肝刺激物质降血糖作用机制的研究

目的 :研究鲨肝刺激物质的降血糖作用机制。方法 :采用四氧嘧啶糖尿病小鼠模型 ,观察鲨肝刺激物质对糖尿病小鼠空腹血糖、果糖胺、胰岛素、肝糖原、己糖激酶、过氧化脂质等生化指标的影响。采用离体培养原代小鼠肝细胞 ,研究鲨肝刺激物质对四氯化碳、对乙酰氨基酚所致肝细胞损伤的作用。结果 :鲨肝刺激物质显著降低糖尿病小鼠空腹血糖和果糖胺水平 ,增加血清胰岛素、肝糖原含量 ,提高己糖激酶活性 ,减轻四氯化碳、对乙酰氨基酚对原代小鼠肝细胞的损伤。结论 :鲨肝刺激物质降血糖作用机制与保护胰岛和肝细胞功能、提高己糖激酶活性、促进肝糖原合成和抗氧化损伤作用密切相关     

Acetaminophen-induced hepatic glycogen depletion and hyperglycemia in mice

Two hours following administration of a hepatotoxic dose of acetaminophen (500 mg/kg, i.p.) to mice, liver sections stained with periodic acid Schiff reagent showed centrilobular hepatic glycogen depletion. A chemical assay revealed that following acetaminophen administration (500 mg/kg) hepatic glycogen was depleted by 65% at 1 hr and 80% at 2 hr, whereas glutathione was depleted by 65% at 0.5 hr and 80% at 1.5 hr. Maximal glycogen depletion (85% at 2.5 hr correlated with maximal hyperglycemia (267 mg/100 ml at 2.5hr). At 4.0 hr following acetaminophen administration, blood glucose levels were not significantly different from saline-treated animals; however, glycogen levels were still maximally depleted. A comparison of the dose-response curves for hepatic glycogen depletion and glutathione depletion showed that acetaminophen (50–500 mg/kg at 2.5 hr) depleted both glycogen and glutathione by similar percentages at each dose. Since acetaminophen (100 mg/kg at 2.5 hr) depleted glutathione and glycogen by approximately 30%, evidence for hepatotoxicity was examined at this dose to determine the potential importance of hepatic necrosis in glycogen depletion. Twenty-four hours following administration of acetaminophen (100 mg/kg) to mice, histological evidence of hepatic necrosis was not detected and serum glutamate pyruvate transaminase (SGPT) levels were not significantly different from saline-treated mice. The potential role of glycogen depletion in altering the acetaminophen-induced hepatotoxicity was examined subsequently. When mice were fasted overnight, hepatic glutathione and glycogen were decreased by 40 and 75%, respectively, and fasted animals showed a dramatic increase in susceptibility to acetaminophen-induced hepatotoxicity as measured by increased SGPT levels. Availability of glucose in the drinking water (5%) overnight resulted in glycogen levels similar to those in fed animals, whereas hepatic glutathione levels were not significantly different from those of fasted animals. Fasted animals and animals given glucose water overnight were equally susceptible to acetaminophen-induced hepatotoxicity, as quantitated by increases in SGPT levels 24 hr after drug administration. The potential role of a reactive metabolite in glycogen depletion was investigated by treating mice with N-acetylcysteine to increase detoxification of the reactive metabolite. N-Acetylcysteine treatment of mice prevented acetaminophen-induced glycogen depletion.     

Insulin secretion and carbohydrate metabolism in the dystrophic mouse.

Dystrophic mice were investigated with regard to their regulation of blood glucose and insulin secretion in vivo. The following were also measured: tissue glycogen levels, activity of the glycogenolytic hydrolase, acid amyloglucosidase, and in vitro glucose utilization by liver, muscle and adipose tissue. Basal levels of blood glucose and plasma insulin of dystrophic mice were essentially within the same range as in the clinically unaffected littermate controls. Dystrophic mice had a decreased tolerance to glucose and glibenclamide; the secretion of insulin in response to these secretagogues was moderately reduced. Insulin release following beta-adrenergic stimulation, however, was increased in the dystrophic mice. Glycogen levels and acid amyloglucosidase activity were increased in dystrophic muscles but were normal in liver. Acid amyloglucosidase activity in pancreatic islets was lower in the dystrophic mouse. Glucose utilization in vitro appeared normal in liver tissue from dystrophic mice; in dystrophic muscle there was a threefold increase in 14CO2-production with no concomitant increase in either glycogen or 14C-incorporation into glycogen. 14CO2 production and 14C-incorporation into lipid and glycogen were increased in dystrophic adipose tissue. We suggest that the decreased glucose tolerance, and the reduced insulin response to glucose in the dystrophic mouse are compensated by an increased glucose utilization in muscle and adipose tissue and an increased beta-adrenergic-mediated secretion of insulin.     

菝葜对小鼠血糖和肝糖元的影响

目的:研究菝葜对小鼠血糖和肝糖元的影响.方法:分别以中药菝葜煎剂10和20g/kg、优降糖(20mg/kg)、降糖灵(40mg/kg)和等容积生理盐水(20ml/kg)灌胃,测定各组正常小鼠的血糖水平及以四氧嘧啶(70mg/kg)、肾上腺素(0.2mg/kg)和葡萄糖(2g/kg)所致小鼠高血糖模型的血糖水平,测定小鼠肝糖元含量.结果:小鼠灌胃菝葜煎剂连续3d或6d,能显著对抗肾上腺素和葡萄糖引起的小鼠血糖升高,降低四氧嘧啶尿病小鼠的血糖浓度,明显增加肝糖元含量,但对正常小鼠的血糖值无明显影响.结论:菝葜对实验性糖尿病小鼠的血糖有明显的抑制作用.     

Hypoglycemic agent YM440 ameliorates the impaired hepatic glycogenesis after glucose loading by increasing glycogen synthase activity in obese Zucker rats

We studied the role of hepatic glycogenesis in glucose intolerance after glucose loading in obese Zucker rats and the effects of YM440 ((Z)-1,4-bis[4-[(3,5-dioxo-1,2,4-oxadiazolidin-2-yl)methyl]phenoxy]but-2-ene) on it. Lean and obese Zucker rats were treated with YM440 (300 mg/kg) for 14 days and then fasted for 20 h. Thirty percent glucose (0.6 g/kg) or saline was administered intravenously followed by NaH14CO3. Gluconeogenesis was evaluated based on the incorporation of 14C-bicarbonate into blood glucose and hepatic glycogen. Obese rats showed an increase in the incorporation of 14C into blood glucose of 2.5-fold compared to lean rats. The glucose loading decreased the 14C-blood glucose release by 18% in obese rats and 43% in lean rats at 45 min. Glucose loading increased the hepatic glycogen content and 14C incorporation into glycogen in lean but not obese rats. YM440 decreased levels of fasting plasma insulin and blood glucose and the hepatic glycogen content by 50% compared with values for untreated obese rats. After glucose loading, YM440 promoted the incorporation of 14C into glycogen and glycogen synthase activity, leading to an improvement in glucose tolerance. These results indicate that glucose intolerance in obese rats was associated with decreased hepatic glycogenesis and YM440 improved the intolerance by normalizing glycogen metabolism.     

FR258900, a novel glycogen phosphorylase inhibitor isolated from Fungus No. 138354. II. Anti-hyperglycemic effects in diabetic animal models

A novel glycogen phosphorylase inhibitor FR258900 was isolated from the cultured broth of a fungal strain No. 138354. We examined the hypoglycemic effects of FR258900 in diabetic animal models. FR258900 treatment significantly reduced the plasma glucose concentrations during oral glucose tolerance tests in diabetic mice models, including db/db mice and STZ-induced diabetic mice. Furthermore, FR258900 treatment resulted in rapid decrease in the plasma glucose levels in db/db mice. These improvements in glucose disposal were accompanied by increased liver glycogen contents, suggesting that the glucose lowering effects of FR258900 were attributed to suppressed hepatic glycogen breakdown and increased hepatic glycogen synthesis. Taken together, our results suggest that glycogen phosphorylase is a potentially useful target in new therapies against diabetes.