Evaluation of morroniside, iridoid glycoside from Corni Fructus, on diabetes-induced alterations such as oxidative stress, inflammation, and apoptosis in the liver of type 2 diabetic db/db mice

The present study was conducted to examine whether morroniside has an ameliorative effect on diabetes-induced alterations such as oxidative stress, inflammation, and apoptosis in the liver of type 2 diabetic db/db mice. Morroniside (20 or 100 mg/kg body weight/d, per os (p.o.)) was administered every day for 8 weeks to db/db mice, and its effect was compared with vehicle-treated db/db and m/m mice. The administration of morroniside decreased the elevated serum glucose concentration in db/db mice, and reduced the increased oxidative biomarkers including the generation of reactive oxygen species and lipid peroxidation in the liver. The db/db mice exhibited the up-regulation of nicotinamide adenine dinucleotide phosphate oxidase subunits, NF-E2-related factor 2 (Nrf2), heme oxygenase-1, nuclear factor-kappa B, cyclooxygenase-2, inducible nitric oxide synthase, monocyte chemotactic protein-1, and intracellular adhesion molecule-1 levels in the liver; however, morroniside treatment significantly reduced those expressions. Moreover, the augmented expressions of apoptosis-related proteins, Bax and cytochrome c, were down-regulated by morroniside administration. Hematoxylin-eosin staining showed that the increased hepatocellular damage in the liver of db/db mice improved on morroniside administration. Taking these into consideration, our findings support the therapeutic evidence for morroniside ameliorating the development of diabetic hepatic complications via regulating oxidative stress, inflammation, and apoptosis.     

重组人胰岛素样生长因子-1对db/db小鼠应激性血糖升高的保护作用

目的:研究重组人胰岛素样生长因子(rhIGF)-1对2型糖尿病(T2DM)伴胰岛素抵抗(IR)小鼠应激性血糖升高的治疗作用。方法:以瘦素受体基因缺陷型db/db小鼠为动物模型,电脉冲刺激诱发应激性高血糖。给予高剂量胰岛素或rhIGF-1进行干预,观察血糖的变化情况。Real time-PCR及Western blot分别检测骨骼肌组织内GLUT4基因的表达水平及GLUT4蛋白含量。结果:在8周龄时瘦素受体基因缺陷的db/db小鼠表现出了明显的肥胖、高血糖及高胰岛素血症。应激后组间血糖水平的差异有统计学意义(F组间=48.915,P<0.05),组内不同时间点血糖水平差异无统计学意义(F时间=1.295,P>0.05),组间和时间无交互效应(F交互=1.046,P>0.05)。采取干预措施后,组间血糖水平差异有统计学意义(F组间=36.947,P<0.05),不同时间点血糖水平差异有统计学意义(F时间=13.880,P<0.05),且组间和时间存在交互效应(F交互=11.769,P<0.05)。IGF-1可显著增加db/db小鼠骨骼肌组织中GLUT4基因的表达及GLUT4蛋白在细胞膜中的含量。结论:rhIGF-1对T2DM小鼠被诱发的应激性高血糖具有较胰岛素更好的控制作用,此作用可能是因骨骼肌细胞中GLUT4的表达及转位增加所致。     

银杏叶提取物对db/db糖尿病小鼠胰岛功能的影响

目的探讨银杏叶提取物EGb761对胰岛分泌功能的影响及相关机制。方法 10只8周龄db/db小鼠随机分为两组,观察组(EGb761组)和糖尿病对照组(db/db组),每组各5只,分别给予EGb761 100 mg/(kg.d)和安慰剂灌胃。另选5只同周龄db/m小鼠给予安慰剂灌胃作为非糖尿病对照(db/m组)。每周监测体重、血糖,8周后行腹腔葡萄糖耐量试验并取胰腺行免疫组化检测,分析胰岛内烟酰胺腺嘌呤二核苷酸磷酸(nicotinamide adenine dinucleotide phosphate,NADPH)氧化酶表达情况。结果 EGb761组血糖、胰岛素分泌功能和胰岛素敏感性、胰岛内NADPH氧化酶gp91phox、p22phox亚基的表达水平、胰岛质量显著改善。结论 EGb761能够降低NADPH氧化酶的表达,减少氧化应激的来源,改善胰岛微环境,从而保护胰岛β细胞。     

Rosiglitazone treatment reversed depression- but not psychosis-like behavior of db/db diabetic mice

The objective of the present study was to examine the effect of long-term management of insulin resistance and hyperglycemia on neurobehavioral deficits in db/db mice. In this study, 5-week-old db/db and lean control mice were fed with rosiglitazone (20 mg/kg/day) mixed or standard chow for a duration of 5 weeks. Mice were monitored weekly for blood glucose concentration. Five weeks after the onset of treatment, they were subjected to the forced swim test (FST), pre-pulse inhibition (PPI), open field test (OFT) and fear-potentiated startle (FPS) test to examine for depression, psychosis-like behavior, locomotor activity and emotional learning, respectively. Rosiglitazone normalized hyperglycemia and improved glucose tolerance. Rosiglitazone significantly reduced immobility time in the FST in db/db mice, suggesting an antidepressant-like effect. However, rosiglitazone failed to reverse disruption of PPI in db/db mice, indicating its ineffectiveness against psychosis-like behavior. In the OFT, rosiglitazone did not affect the activity of db/db mice, suggesting its antidepressant-like effect was independent of changes in locomotor activity. In the FPS test, db/db mice showed impaired emotional learning and rosiglitazone failed to correct it. In conclusion, long-term blood glucose management in type-2 diabetics may help to limit the co-occurrence of depression but not the psychotic symptoms and ability to cope with stress.     

自发性2型糖尿病模型db/db小鼠生物学特性研究

目的对db/db小鼠进行生物学特性研究,满足糖尿病研究的需要。方法在试验周期内,测定db/db小鼠的空腹血糖、体质量及摄食饮水量,并测定21周龄模型动物的糖耐量、血中胰岛素、胰高血糖素、三酰甘油、总胆固醇等指标的水平,进行胰腺的免疫组化双重染色及主要脏器的病理学检查,并与db/m小鼠进行比较。结果与对照组db/m小鼠比较,db/db小鼠过度肥胖,伴有高血糖、胰岛素抵抗、脂质代谢紊乱,且肝脏和胰腺组织均出现明显病变,胰腺免疫组化双重染色结果与血液学测定结果一致,并可观察到胰岛中A细胞和B细胞的分布变化情况。结论对自发性2型糖尿病模型db/db小鼠所做的相关生物学特性检测,可供糖尿病研究参考。     

Chronic oral supplementation with sepiapterin prevents endothelial dysfunction and oxidative stress in small mesenteric arteries from diabetic (db/db) mice

We previously reported that acute incubation with tetrahydrobiopterin (BH4) or sepiapterin, a cofactor for endothelial nitric oxide synthase and a stable precursor of BH4, respectively, enhanced the acetylcholine (Ach)-induced relaxation of isolated small mesenteric arteries (SMA) from diabetic (db/db) mice. In this study, we investigated the effect of chronic oral supplementation of sepiapterin (10 mg x kg-1 x day-1) to db/db mice on endothelium function, biopterin levels and lipid peroxidation in SMA. Oral dietary supplementation with sepiapterin had no effect on glucose, triglyceride, cholesterol levels and body weight. SMA from db/db mice showed enhanced vascular reactivity to phenylephrine, which was corrected with sepiapterin supplementation. Furthermore, Ach, but not sodium nitroprusside-induced relaxation, was improved with sepiapterin supplementation in db/db mice. BH4 levels and guanosine triphosphate cyclohydrolase I activity in SMA were similar in db/+ and db/db mice. Sepiapterin treatment had no effects on BH4 or guanosine triphosphate cyclohydrolase I activity. However, the level of dihydrobiopterin+biopterin was higher in SMA from db/db mice, which was corrected following sepiapterin treatment. Thiobarbituric acid reactive substance, malondialdehyde, a marker of lipid peroxidation, was higher in SMA from db/db mice, and was normalized by sepiapterin treatment. These results indicate that sepiapterin improves endothelial dysfunction in SMA from db/db mice by reducing oxidative stress. Furthermore, these results suggest that decreased biosynthesis of BH4 may not be the basis for endothelial dysfunction in SMA from db/db mice.     

Preservative effect of electrolyzed reduced water on pancreatic beta-cell mass in diabetic db/db mice

Oxidative stress is produced under diabetic conditions and involved in progression of pancreatic beta-cell dysfunction. Both an increase in reactive oxygen free radical species (ROS) and a decrease in the antioxidant defense mechanism lead to the increase in oxidative stress in diabetes. Electrolyzed reduced water (ERW) with ROS scavenging ability may have a potential effect on diabetic animals, a model for high oxidative stress. Therefore, the present study examined the possible anti-diabetic effect of ERW in genetically diabetic mouse strain C57BL/6J-db/db (db/db). ERW with ROS scavenging ability reduced the blood glucose concentration, increased blood insulin level, improved glucose tolerance and preserved beta-cell mass in db/db mice. The present data suggest that ERW may protects beta-cell damage and would be useful for antidiabetic agent.     

基因缺陷型2型糖尿病模型动物db/db小鼠早期生物学特性研究

目的研究基因缺陷型2型糖尿病模型动物db/db小鼠的早期生物学特性,为db/db小鼠应用于降糖药物的研究奠定基础。方法采用db/db小鼠为模型组动物,db/m小鼠为对照组动物,测定两组小鼠的体质量、食量、饮水量、空腹血糖、正常饮食血糖、糖耐量、胰岛素耐量;于第14周眼底静脉丛取血,分离血清,测定糖化血清蛋白（GSP）、三酰甘油（TG）、总胆固醇（TC）;取肝、胰腺、腹部脂肪等主要脏器组织进行组织病理学检查。结果与对照组比较,db/db小鼠体质量、食量、饮水量显著增加;空腹血糖及正常饮食血糖显著升高,整个实验期血糖水平稳定;糖耐量异常、胰岛素耐量异常,对外源胰岛素敏感性显著降低;血清GSP、TG、TC含量显著升高,腹部脂肪质量显著增加,肝组织不同程度的空泡变性,脂肪组织中脂肪细胞体积增大,胰腺中胰岛细胞胞浆减少、血管扩张。结论 db/db小鼠早期脂质代谢紊乱,血糖、血脂显著升高,糖耐量及胰岛素耐量异常,血糖水平稳定,是研究2型糖尿病较为理想的模型。     

大黄酸对db/db小鼠胰岛功能及炎症氧化损伤标志物表达的影响

目的通过先天性2型糖尿病动物模型db/db小鼠,探讨大黄酸对胰岛功能及炎症、氧化损伤标志物表达的影响。方法选取30只4周龄db/db雄性小鼠,随机分成治疗组和对照组,每组15只。治疗组每日固定时间给予大黄酸(120mg/kg,1%纤维素钠溶解)灌胃,对照组给予相同体积的1%纤维素钠,连续给药8周。投药结束后行经腹腔葡萄糖耐量试验(IPGTT)并测定胰岛素水平,用曲线下面积(AUC)代表胰岛素分泌水平,并通过计算IPGTT的0~30min胰岛素AUC评估早期胰岛素分泌功能。同时对小鼠胰腺进行胰岛素、核因子-κB(NF-κB)及8-羟基脱氧鸟苷(8-OHdG)免疫组织化学染色。结果与对照组相比,治疗组糖负荷后0,30,60,120min的血糖水平明显下降,而30,60,120min的胰岛素水平明显升高,尤其是早期相胰岛素水平升高更明显。同时,大黄酸治疗组小鼠胰岛素染色明显增强,NF-κB及8-OHdG表达明显受抑制。结论早期大黄酸治疗可以明显改善db/db小鼠的葡萄糖耐量,恢复早期胰岛素分泌功能,保护胰岛功能;同时早期大黄酸治疗明显减少炎症、氧化损伤标志物的表达。     

Effects of aminoguanidine and desferrioxamine on some vascular and biochemical changes associated with streptozotocin-induced hyperglycaemia in rats.

The effects of aminoguanidine (AG; 100 mg x kg(-1)) and desferrioxamine (DFO; 50 mg x kg(-1)) on some vascular and biochemical changes associated with streptozotocin (STZ; 65 mg x kg(-1); i.p.)-induced hyperglycaemia were investigated in rats. Both AG and DFO were administered i.p., once daily, for 14 consecutive days to normal and hyperglycaemic animals. The responsiveness of the isolated aortic rings to phenylephrine (PE) was tested. In addition, biochemical markers for oxidative stress such as plasma levels of lipid peroxides and total thiols, as well as the activities of erythrocytic superoxide dismutase (SOD) and whole blood glutathione peroxidase (GSH-Px) were assessed. Results of the present study indicated that induction of hyperglycaemia was associated with increased aortic ring responsiveness to PE, loss in body weight, increase in urine volume, elevation of plasma total thiols and lipid peroxide levels and elevated SOD and GSH-Px enzymatic activities. Treatment of normal rats with AG reduced the response of their aortae to PE. Furthermore, a profound increase in body weight without any significant change in the measured biochemical parameters was observed. In hyperglycaemic animals, AG tended to normalize the enhanced aortic response to PE and modulated STZ-induced biochemical changes without affecting the elevated plasma glucose level. Treatment of normal rats with DFO reduced the response of their aortae to PE and decreased their body weight without altering any of the chosen biochemical parameters. In hyperglycaemic animals, DFO attenuated the responsiveness of their aortae to PE and at the same time, did not affect the loss in body weight and the elevation of plasma glucose level observed in the hyperglycaemic group. Additionally, DFO normalized the elevated plasma level of total thiols and exerted a modulatory influence on the enhanced activities of SOD and GSH-Px as well as on the increased levels of lipid peroxides. Our data lend further credence for the contribution of oxidative stress in the vascular and biochemical changes associated with STZ-induced hyperglycaemia. It is also apparent that advanced glycosylation end products and nitric oxide might be involved. Until clinical studies prove the efficacy and safety of these drugs, specific agents which could scavenge free radicals and block protein glycosylation seem beneficial as a helpful adjunct to the therapy of diabetes.     

Impairment of endothelium-dependent ACh-induced relaxation in aorta of diabetic db/db mice—possible dysfunction of receptor and/or receptor–G protein coupling

Diabetes is a risk factor of ischemic heart disease, cerebral ischemia, and atherosclerosis, in which endothelial dysfunction plays a role in the pathogenesis. We examined vascular responses in the aorta of pre-diabetic db/db mice with normoglycemia, hyperlipidemia, and hyperinsulinemia (6 weeks old), and diabetic db/db mice with hyperglycemia, hyperlipidemia, and hyperinsulinemia (11 weeks old) in comparison with age-matched non-diabetic db/+ mice. Prostaglandin F(2alpha) (PGF(2alpha))-induced contraction was significantly enhanced in the aorta of diabetic but not pre-diabetic db/db mice compared to age-matched non-diabetic db/+ mice. Acetylcholine (ACh), adenosine-5'-diphosphate (ADP), NaF, a G protein activator and A-23187, a Ca-ionophore, caused endothelium-dependent and nitric oxide (NO)-mediated relaxation, and sodium nitroprusside (SNP), an NO donor, caused endothelium-independent relaxation in the pre-contracted aorta of db/db mice. Maximal endothelium-dependent ACh-induced relaxation was reduced in diabetic but not pre-diabetic db/db mice compared to age-matched db/+ mice, while maximal SNP-induced relaxation was not different between diabetic and non-diabetic mice. ACh-induced relaxation in diabetic db/db mice was not affected by ozagrel, a thromboxane A(2) (TXA(2)) synthetase inhibitor, or acetylsalicylic acid (aspirin), a cyclooxygenase inhibitor, suggesting no involvement of endogenous TXA(2) or prostanoids in the reduction of relaxation. Maximal endothelium-dependent ADP-, A-23187-, and NaF-induced relaxation was not reduced in diabetic db/db mice. EC(50) values for ACh- and SNP-induced relaxation were increased in diabetic but not pre-diabetic db/db mice, suggesting decreases in sensitivity to NO in diabetic mice. Two-week treatment with KV-5070, a PPARgamma agonist, lowered plasma glucose, triglyceride (TG), and insulin but not cholesterol, and reversed the reduced ACh-induced relaxation. In conclusion, ACh-induced endothelium-dependent relaxation is impaired in diabetic db/db mice, probably due to the dysfunction of ACh receptors and/or receptor-G protein coupling. Endothelial dysfunction was not genetic and was considered to be initiated primarily by hyperglycemia, and was improved by anti-diabetic treatment with a PPARgamma agonist.     

Angiotensin Ⅱ receptor blocker provides pancreatic β-cell protection independent of blood pressure lowering in diabetic db/db mice1

AIM: Several epidemiological studies have suggested that treatment with angiotensin II type 1 receptor blocker provided a risk reduction of developing type 2 diabetes. The aim of this study was to investigate whether and how chronic candesartan treatment can attenuate the deleterious influence of the hyperactive local intra-islet renin-angiotensin system in the diabetes state. METHODS: Eight-week-old db/db mice were randomized to candesartan 1 mg/kg, candesartan 10 mg/kg, manidipine 10 mg/kg, or placebo via gavage for 6 weeks. Their age-matched nondiabetic littermates db/m mice were treated with placebo and acted as nondiabetic controls. After 6 weeks' treatment, an intraperitoneal glucose tolerance test, immunohistochemical staining of oxidative stress markers, insulin, CD31, azan staining and an electron microscopy observation were performed. RESULTS: Chronic candesartan treatment provided an improvement of glucose tolerance, and greatly rescued islet beta-cell mass. Candesartan treatment also notably decreased staining intensity of oxidative stress markers, as well as attenuating intra-islet fibrosis and improving blood supply in the islet. In the electron microscopy observation, candesartan-treated animals exhibited improved granulation and less remarkable endoplasmic reticulum and Golgi bodies; furthermore, candesartan treatment greatly relieved the swelling of mitochondria to nearly normal. Both the benefits of reducing oxidative stress and ultrastructure protection were in a dose-dependent and blood pressure-independent manner. CONCLUSION: After diabetes was initiated, candesartan treatment could not reverse the state of diabetes, but it effectively improved glucose tolerance and protected beta-cell function by attenuating oxidative stress, islet fibrosis, sparsity of blood supply and ultrastructure disruption in a dose-dependent and blood pressure-independent manner.     

牛蒡子苷对自发型糖尿病db/db小鼠降血糖作用的实验研究

目的：观察牛蒡子苷对db/db自发型糖尿病小鼠的降血糖作用及其潜在的作用机制。方法：40只db/db小鼠随机分为5组：模型对照组,牛蒡子苷75,150,300 mg·kg^-1组和二甲双胍300 mg·kg^-1组,同时设置db/m小鼠空白对照组,灌胃给予相应药物或溶媒,连续4周。给药3周后,进行口服糖耐量试验。4周给药结束后,小鼠禁食12 h,称体质量,检测空腹血糖值（FBG）,处死动物,取血清,检测胰岛素（INS）、糖化血清蛋白（GSP）、三酰甘油（TG）、总胆固醇（TC）和脂联素（APN）含量。结果：与模型对照组比较,牛蒡子苷中、高剂量能显著降低db/db小鼠FBG、INS、GSP、TG、TC和APN的血清浓度,改善小鼠糖耐量（P〈0.05或0.01）。结论：牛蒡子苷能显著改善db/db小鼠糖脂代紊乱,减轻胰岛素抵抗,其作用机制可能与上调脂联素表达有关。     

Sulfaphenazole treatment restores endothelium-dependent vasodilation in diabetic mice

Vascular dysfunction is linked with increased free radical generation and is a major contributor to the high mortality rates observed in diabetes. Several probable sources of free radical generation have been suggested in diabetes, including cytochrome P450 (CYP) monooxygenase-dependent pathways. CYP-mediated superoxide production reduces nitric oxide (NO) bioavailability. In this study, we focus on the contribution of monooxygenase enzyme-generated reactive oxygen species in vascular dysfunction in an experimental model of diabetes mellitus type II. Diabetic male mice (db/db strain) and their age-matched controls received daily intraperitoneal injections of either the CYP 2C inhibitor sulfaphenazole (5.13 mg/kg) or saline (vehicle control) for 8 weeks. Although sulfaphenazole did not change endothelium-dependent vasodilation in control mice, it restored endothelium-mediated relaxation in db/db mice. We report for the first time that CYP 2C inhibition reduces oxidative stress (measured as plasma levels of 8-isoprostane), increases NO bioavailability (measured as NO(2)(-)) and restores endothelial function in db/db mice without affecting plasma glucose levels. Based on our findings, we speculate that inhibition of free radical generating CYP 450 monooxygenase enzymes restores endothelium-dependent vasodilation to acetylcholine. In addition, it reduces oxidative stress and increases NO bioavailability.     

滋阴益气活血泄浊法对db／db小鼠糖代谢的影响

目的：探讨滋阴益气活血泄浊法对db／db小鼠整体水平糖代谢的影响。方法选取12~14周龄雄性db／db小鼠,按空腹血糖及体质量随机分成模型组、阿卡波糖组、石斛合剂序贯组（以下简称序贯组）;选db／m为正常对照组。连续灌胃给药共6个循环（42d）。治疗前测各药物对淀粉耐量影响。每2周期测空腹血糖（FBG）,实验结束前测口服葡萄糖耐量（OGTT）和测定糖化血清蛋白（GSP）、血清胰岛素（Ins）以及各药物干预后的肠上皮α-葡萄糖苷酶活性。结果石斛合剂1方和2方单次给药均能明显降低db／db小鼠淀粉耐量30,60,120min血糖;随治疗循环数增加,序贯组的FBG逐步下降;与模型组比较,序贯组FBG、GSP和Ins显著下降（P<0.05）,改善葡萄糖耐量;石斛合剂1方、2方降低肠上皮α-葡萄糖苷酶活性（P<0.05）。结论石斛合剂有明确的α-葡萄糖苷酶抑制作用,序贯治疗能降低db／db小鼠的血糖相关指标,降低高胰岛素血症,表明滋阴益气活血泄浊法的降糖机制可能与抑制α-葡萄糖苷酶活性有关。     

Comparison of gene expression changes induced by biguanides in db/db mice liver

Large-scale clinical studies have shown that the biguanide drug metformin, widely used for type 2 diabetes, to be very safe. By contrast, another biguanide, phenformin, has been withdrawn from major markets because of a high incidence of serious adverse effects. The difference in mode of action between the two biguanides remains unclear. To gain insight into the different modes of action of the two drugs, we performed global gene expression profiling using the livers of obese diabetic db/db mice after a single administration of phenformin or metformin at levels sufficient to cause a significant reduction in blood glucose level. Metformin induced modest expression changes, including G6pc in the liver as previously reported. By contrast, phenformin caused changes in expression level of many additional genes. We used a knowledge-based bioinformatic analysis to study the effects of phenformin. Differentially expressed genes identified in this study constitute a large gene network, which may be related to cell death, inflammation or wound response. Our results suggest that the two biguanides show a similar hypoglycemic effect in db/db mice, but phenformin induces a greater stress on the liver even a short time after a single administration. These findings provide a novel insight into the cause of the relatively high occurrence of serious adverse effect after phenformin treatment.     

Cellular basis of endothelial dysfunction in small mesenteric arteries from spontaneously diabetic (db/db -/-) mice: role of decreased tetrahydrobiopterin bioavailability

1. Endothelium-dependent and -independent regulation of vascular tone in small mesenteric arteries (SMA) from control (db/db +/?) and diabetic (db/db -/-) mice was compared. 2. Phenylephrine-induced maximum contraction, but not sensitivity, of SMA in db/db -/- compared to db/db +/? was enhanced. 3. Acetylcholine (ACh), but not sodium nitroprusside (SNP), -induced relaxation was reduced in SMA from db/db -/- compared to db/db +/?. 4. ACh-induced relaxation of SMA was inhibited by a combination of N(omega)-nitro-L-arginine and indomethacin in db/db +/?, but not in db/db -/-. 5. Acute incubation of SMA with tetrahydrobiopterin (BH(4), 10 microM) and sepiapterin (100 microM) enhanced ACh-induced relaxation in SMA from db/db -/-, but not from db/db +/? 2,4-diamino-6-hydroxypyrimidine, an inhibitor of GTP cyclohydrolase I, (10 mM), impaired the sensitivity of SMA from db/db +/? to ACh, which was restored by co-incubation with BH(4) (10 microM). 6. BH(4) and superoxide dismutase (SOD, 150 u ml(-1)), either alone or in combination, had no effect on either ACh or SNP-induced relaxation in SMA from eNOS -/- mice. 7. Incubation of SMA with SOD (150 iu ml(-1)), catalase (200 iu ml(-1)) and L-arginine (1 mM) had no effect on ACh-induced relaxation of SMA. However, the combination of polyethylene glycol-SOD (200 iu ml(-1)) and catalase (80 u ml(-1)) improved the sensitivity of ACh-induced relaxation in db/db -/-, but not in db/db +/?. 8. These data suggest that increased production of superoxide anions and decreased availability of BH(4) result in an 'uncoupling' of nitric oxide synthase and endothelial dysfunction in SMA from db/db -/- mice.     

千金黄连方对db/db小鼠血糖的影响

目的 探讨千金黄连方对2型糖尿病模型动物db/db小鼠血糖的影响。方法 C57BL/6J小鼠10只（雌雄各半）作为对照组,将db/db小鼠60只（雌雄各半）按血糖值随机分为6组：模型组、二甲双胍（0.25 g·kg^-1）组、金芪降糖片（4.2 g·kg^-1）组和千金黄连方高、中、低剂量（生药13.00、6.50、3.25 g·kg^-1）组。每天ig给药1次,给药体积20 mL·kg^-1,对照组及模型组ig给予等量去离子水。血糖仪测定千金黄连方给药1次对糖耐量、空腹血糖的影响及多次给药对空腹血糖、糖耐量、混合饮食餐后血糖、淀粉耐量（碳水化合物饮食餐后血糖）的影响;连续给药12周后,试剂盒法检测血清中糖化血清蛋白（GSP）、糖化血红蛋白（GHb）、胰岛素水平;小鼠放血处死后,剪开腹部,取腹部脂肪称质量,计算脂肪系数;HE染色后对肝组织进行病理学检查。结果 给药1次,与模型组比较,给药后1~2 h千金黄连方高剂量能显著降低小鼠空腹血糖值和糖耐量血糖值（P<0.05、0.01）。与模型组比较,多次给予千金黄连方能显著降低小鼠空腹血糖值、显著降低葡萄糖耐量血糖值、显著降低混合饮食餐后血糖值和淀粉耐量血糖值（P<0.05、0.01、0.01）。与模型组比较,千金黄连方高、中、低剂量组小鼠GHb、GSP及胰岛素水平均显著下降（P<0.05、0.01、0.001）;高、中剂量组小鼠腹部脂肪系数显著下降（P<0.05、0.01）;高、低剂量对肝脏空泡变性程度有减轻作用。结论 千金黄连方能显著降低db/db小鼠空腹血糖,改善糖耐量异常及增强胰岛素敏感性,显著减少腹部脂肪系数,对肝细胞的损伤也有一定的改善作用;其降血糖作用与二甲双胍相当,强于金芪降糖片,其改善胰岛素抵抗、增加胰岛素敏感性的作用强于二甲双胍和金芪降糖片。