黔产粗毛淫羊藿与黔岭淫羊藿总黄酮对2型糖尿病小鼠IR相关因子的影响

目的:研究黔产粗毛淫羊藿与黔岭淫羊藿中总黄酮(TFE)对四氧嘧啶(ALX)诱发2型糖尿病模型小鼠胰岛素抵抗(IR)相关因子的影响。方法:雄性小鼠100只,随机取10只为正常组,喂养基础饲料;其余的采用高脂饲料喂养小鼠6周,单次ip 2%ALX(200 mg·kg-1),建立2型糖尿病小鼠模型。将糖尿病模型小鼠随机分为6组,每组10只,分别为模型组,二甲双胍(150 mg·kg-1)组,两种TFE分别按剂量100,50 mg·kg-1分组,ig给药14 d。于末次给药后取血,检测小鼠血清胰岛素(FINS)、C肽水平;检测小鼠空腹血糖(FBG),注射胰岛素(Ins)40 min后血糖(BG);计算胰岛素耐量(ITT),胰岛素抵抗指数(HOMA-IR)和胰腺指数;观察小鼠胰腺形态学改变。结果:与正常组比较,模型组小鼠血糖升高非常显著(P0.01),空腹血清中C肽,FINS有明显增加(P0.05),胰腺组织损伤极为严重(P0.01),胰腺指数降低非常显著(P0.01)。与模型组相比,两种淫羊藿TFE均能够较明显地改善模型小鼠ITT(P0.05),降低模型小鼠血清C肽、FINS含量及HOMA-IR(P0.05),提高模型小鼠的胰腺指数(P0.05),明显地修复模型小鼠的胰腺组织损伤(P0.05)。两种TFE同剂量组相比,以粗毛淫羊藿TFE作用较为显著(P0.05,P0.01)。结论:两种黔产淫羊藿TFE对ALX诱生的2型糖尿病模型小鼠能增加胰岛素敏感性,较明显地改善模型小鼠胰岛素抵抗相关因子,保护受损的胰腺组织。以粗毛淫羊藿TFE作用较为明显,这可能与粗毛淫羊藿TFE中淫羊藿苷(ICA)含量高有较大关系。     

On the accumulation of alloxan in the pancreatic β-cells

Summary Autoradiographic studies revealed that the radioactivity in the pancreatic islets was higher than in any other mouse tissue after intravenous injections of tracer doses of ¹⁴C-2-alloxan. The concentration of radioactivity in the endocrine pancreas concerned a great majority of the cells indicating that at least cells were involved. The uptake of the radioisotope in the pancreatic islets was considerably reduced when the small amounts of ¹⁴C-2-alloxan were complemented with carrier to bring up the total dose to the diabetogenic level or were proceeded by higher doses of non-radioactive alloxan. There was no accumulation of radioactivity in the islets after injection of the non-diabetogenic conversion products of ¹⁴C-2-alloxan obtained in an alkaline medium and only insignificant uptake was noted after exposure of the radioactive alloxan to the reactive SH-groups of glutathione. The absence of significant radioactivity in the islets of growing animals after tracer doses of ¹⁴C-2-alloxan suggests that the ability of the cells to concentrate alloxan is confined to the adult age.This study was supported by grants from the Swedish Medical Research Council, the United States Public Health Service (AM-05759-05) and Knut and Alice Wallenbergs Stiftelse.     

Oxygen free radical scavengers protect rat islet cells from damage by cytokines

Summary A possible role for oxygen free radicals in mediating the cytotoxic effects of cytokines in islets was sought by the use of agents that scavenge free radicals. Rat islet cell monolayer cultures were incubated for 6 days with t-butylhy-droperoxide, alloxan, streptozotocin, or the cytokines, interleukin 1, tumour necrosis factor, and interferon gamma, without and together with the oxygen free radical scavenger combination of dimethylthiourea and citiolone, and islet cell lysis was measured in a ¹⁵chromium cytotoxicity assay. The free radical scavengers significantly inhibited the islet cell cytotoxic effects of t-butylhydroperoxide and alloxan, but not streptozotocin. Similarly, the cytotoxic effects of the cytokine combinations of interleukin 1 plus tumour necrosis factor, interferon gamma plus tumour necrosis factor, and interferon gamma plus interleukin 1 were significantly inhibited by the free radical scavenger combination of dimethylthiourea and citiolone. These results suggest that the cytokine products of macrophages and lymphocytes infiltrating islets in Type 1 (insulin-dependent) diabetes may contribute to B-cell damage by inducing the production of oxygen free radicals in the islet cells.     

Oxidative stress increased hepatotoxicity induced by nano‐titanium dioxide in BRL‐3A cells and Sprague–Dawley rats

Extensive studies have shown that titanium dioxide (TiO₂) nanomaterials (NMs) can cause toxicity in vitro and in vivo under normal conditions. However, an adverse effect induced by nano‐TiO₂ in many diseased conditions, typically characterized by oxidative stress (OS), remains unknown. We investigated the toxicity of nano‐TiO₂ in rat liver cells (BRL‐3A) and Sprague–Dawley (SD) rat livers under OS conditions, which were generated using hydrogen peroxide (H₂O₂) in vitro and alloxan in vivo, respectively. In vitro results showed that cell death ratios after nano‐TiO₂ exposure were significantly enhanced (up to 2.62‐fold) in BRL‐3A cells under OS conditions, compared with normal controls. Significant interactions between OS conditions and nano‐TiO₂ resulted in the rapid G0/G1 to S phase transition and G2/M arrest, which were opposite to G0/G1 phase arrest in cells after NMs exposure only. In vivo results showed that obvious pathological changes in rat livers and the increased activities of four enzymes (i.e. aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase and alkaline phosphatase) owing to liver damage after nano‐TiO₂ exposure under OS conditions, compared with their healthy controls. In addition, compared with increased hepatotoxicity after nano‐TiO₂ exposure, micro‐TiO₂ showed no adverse effects to cells and rat livers under OS conditions. Our results suggested that OS conditions synergistically increase nano‐TiO₂ induced toxicity in vitro and in vivo, indicating that the evaluation of nanotoxicity under OS conditions is essentially needed prior to various applications of NMs in foods, cosmetics and potential treatment of diseases. Copyright © 2013 John Wiley & Sons, Ltd.     

海带在四氧嘧啶糖尿病大鼠模型中的降糖作用

目的探讨海带在四氧嘧啶糖尿病模型大鼠中的降血糖作用及其机制。方法健康♂Wistar大鼠60只,随机取10只作为对照组,其余50只腹腔注射四氧嘧啶建立高血糖动物模型,饲料中添加含有海带的饲料喂养干预治疗,分为低(2.5 g.kg-1)、中(10 g.kg-1)和高(25 g.kg-1)3个剂量组。自动血糖仪测大鼠空腹血糖(FBG),酶联免疫吸附法检测血清胰岛素(Insulin)水平,硫代巴比妥酸法检测血清脂质过氧化物丙二醛(MDA)含量,硝酸还原酶法检测血清一氧化氮(NO)含量,黄嘌呤氧化酶法测定血清超氧化物歧化酶(SOD)活性,化学比色法测定谷胱甘肽过氧化物酶(GSH-Px)活性。结果经海带治疗后,动物血清胰岛素水平较模型组升高(P<0.05),中、高剂量组动物FBG水平较模型组降低(P<0.05);其血清MDA和NO水平低于模型组,而血清SOD和GSH-Px活性高于模型组,其中中、高剂量组与模型组比较差异有显著性(P<0.05)。各指标在中剂量与高剂量组之间差异无显著性(P>0.05)。结论海带可通过增强机体的抗氧化作用,促进胰岛细胞分泌功能恢复而发挥降血糖作用,其理想剂量为每日10 g.kg-1。     

Gene transfer of endothelial nitric oxide synthase alters endothelium-dependent relaxations in aortas from diabetic rabbits

Aims/hypothesis. Cardiovascular disease is the leading cause of death in diabetes mellitus. Abnormal endothelium-dependent relaxation is observed both in humans and in animal models of diabetes mellitus and decreased bioavailability of nitric oxide (NO) is thought to be involved in this defect. Therefore, the aim of this study was to test whether adenovirus-mediated gene transfer of endothelial nitric oxide synthase (eNOS) alters vascular reactivity of diabetic vessels.¶Methods. Vascular reactivity was first assessed in thoracic aortas and carotid arteries from nine alloxan-induced diabetic (plasma glucose, 26.5 ± 1.2 mmol/l; HbA_{1 c}, 6.4 ± 0.3 %) and nine control rabbits (plasma glucose, 11.1 ± 1.3 mmol/l; HbA_{1 c}, 2.1 ± 0.1 %). Vascular reactivity was next examined in thoracic aortas of diabetic animals after ex vivo transduction with replication-deficient adenovirus encoding gene for eNOS (AdeNOS) or β-galactosidase (Adβ gal).¶Results. After 10 weeks of hyperglycaemia, endothelium-dependent relaxation to acetylcholine was impaired in diabetic aorta, but was normal in carotid arteries from diabetic rabbits. In contrast, responses of both vessels to calcium ionophore and nitric oxide donor were normal. Histochemical staining for β-galactosidase and immunohistochemistry for eNOS showed transgene expression in the endothelium and adventitia in Adβ gal and AdeNOS transduced vessels, respectively. During submaximum contractions with phenylephrine, relaxations to low concentrations of acetylcholine (3 × 10^–8 to 10^–7 mol/l) were augmented in AdeNOS transduced diabetic vessels.¶Conclusion/interpretation. These findings suggest that adenovirus-mediated gene transfer of eNOS to diabetic aorta alters vascular reactivity. [Diabetologia (2000) 43: 340–347]     

Antidiabetic activity of the mangrove species Ceriops decandra in alloxan-induced diabetic rats

Background: Diabetes is a series of disorders characterized by increased fasting and postprandial glucose concentration and insulin deficiency and/or decreased insulin action. Although there are a number of commercially available drugs for the treatment of diabetes, their long‐term use may cause unwanted side effects. Consequently, many studies are underway to find natural remedies that can effectively reduce the intensity of diabetes. The aim of the present study was to evaluate the antidiabetic activity of the mangrove species Ceriops decandra. Methods: The effects of daily oral administration of an ethanolic extract from the leaves of C. decandra (30, 60, 120 mg/kg) for 30 days on blood glucose, hemoglobin (Hb), HbA1c, liver glycogen and some carbohydrate metabolic enzymes were evaluated in normal and alloxan‐induced diabetic rats. The effects of these extracts were compared with the effect of 30‐days treatment with 0.1 mg/kg, p.o., glibenclamide, a commercially available drug commonly used in the treatment of diabetes. Results: Oral administration of 120 mg/kg extract modulated all the parameters evaluated to levels seen in control rats. The effects of 120 mg/kg extract were comparable to those of glibenclamide. Conclusion: The extract of the mangrove plant C. decandra exhibited promising antidiabetic activity and could be considered for further evaluation in clinical studies and drug development.     

Phytopharmacological evaluation of Byesukar for hypoglycaemic activity and its effect on lipid profile and hepatic enzymes of glucose metabolism in diabetic rats: Original Article

Many anti-diabetic herbal preparations have been recommended in alternative systems of medicine for the treatment of diabetes. No systematic study has been done on the anti-diabetic efficacy of Byesukar, a polyherbal formulation to treat diabetes. The anti-diabetic efficacy of byesukar ethanol extract was evaluated in an animal model of diabetes induced by alloxan. Male Wistar rats were divided in to four groups. Group 1 was normal control group; group 2 and 3 received alloxan. After inducing experimental diabetes group 2 served as diabetic control; group 3 received byesukar (500 mg/kg body weight) orally for 30 consecutive days. Group 4 were normal rats which received byesukar extract alone. The effect of byesukar on glucose level in diabetic rats was studied and the level of glucose metabolizing enzymes (Hexokinase, glucose-6-phosphatase and fructose 1, 6-bisphosphatase) in the liver and kidney were estimated. The effect of byesukar on the serum and tissue lipid profile (Cholesterol, triglycerides, phospholipids and free fatty acids) were also estimated in diabetic rats. Our results indicate that treatment with byesukar resulted in significant reduction of blood glucose, tissue glucose-6-phosphatase and fructose 1, 6-bisphosphatase activity. The decreased tissue hexokinase activity in diabetes state was found to be significantly increased by byesukar treatment. Also the byesukar treated diabetic rats showed a significant decrease in the tissue lipid profile compared to the diabetic rats. In conclusion the decreased blood glucose accompanied with decreased lipid profile and changes in the activities of the glucose metabolizing enzymes shows the antidiabetic effect of byesukar.     

Monoamines in the pancreatic islets of the mouse

Summary The functional significance of 5-hydroxytryptamine (5-HT) storage in the pancreatic B cells for insulin secreting mechanisms was studied in normal micein vivo. Pretreatment of the animals withL-5-hydroxytryptophan (L-5-HTP) markedly decreased the insulin releasing capacity after sulphonylurea stimulation. This inhibition of insulin release could be abolished by previous administration of an inhibitor of aromatic amino acid decarboxylation. On the other hand, pretreatment with the monoamine oxidase inhibitor nialamide alone, decreased sulphonylurea-induced insulin release. The combined treatment with nialamide andL-5-HTP did not further decrease the insulin response. Insulin release induced byL-isopropylnoradrenaline (L-IPNA) was also found to diminish after previous administration ofL-5-HTP or nialamide; but, unlike the insulin response to sulphonylurea, insulin release induced by IPNA could be totally suppressed by the combined treatment of nialamide or pargyline andL-5-HTP. Insulin release induced by glucose was not significantly influenced with any of the above treatments. Basal levels of plasma insulin were not affected byL-5-HTP injection, and were not consistently diminished by the combined treatment with monoamine oxidase inhibitor andL-5-HTP. The combined treatment with monoamine oxidase inhibitors andL-5-HTP was found to elicit a profound hypoglycaemia in both normal and alloxan-diabetic mice. The hypoglycaemic condition was accompanied by exhaustion of liver and muscle glycogen. The hypoglycaemia could be abolished by previous treatment with an inhibitor of aromatic amino acid decarboxylation. Combined treatment with pargyline and 5-HT brought about a marked hyperglycaemia. It is concluded that: 1. intracellular levels of 5-HT in the pancreatic B cells possess the ability to modify insulin secreting mechanisms; and 2. the hypoglycaemic action of monoamine oxidase inhibitors is brought about by raised intracellular levels of 5-HT, which is accompanied by a markedly increased glucose utilization by the tissues.This work was supported by the Medical Faculty, University of Lund, Sweden. The skilful technical assistance of Mrs. Lena Kvist, Miss Anita Åkesson and Miss Ann-Christin Helander is gratefully acknowledged.     

黄精多糖对四氧嘧啶诱导的糖尿病小鼠血糖和抗氧化作用的影响

目的研究黄精多糖(PSP)对四氧嘧啶诱导的糖尿病小鼠的保护作用及对其氧自由基代谢的影响。方法采用四氧嘧啶腹腔注射法,建立糖尿病小鼠模型;测定小鼠的血糖,胸腺、肝脏、脾脏和肾脏重量;化学比色法分别检测血清和肝脏中的T-SOD、GSH-Px活性及MDA含量。结果与模型组比较,PSP(0.5、1g/kg,ig×14d)能明显降低糖尿病小鼠血糖(P<0.05),显著提高糖尿病小鼠的胸腺、脾脏和肝脏指数,提高血清和肝脏组织中的T-SOD和GSH-Px活性,降低MDA含量。结论PSP对四氧嘧啶诱导的糖尿病小鼠有一定的保护作用,其机制可能与抗氧化作用有关。