转录激活因子6：潜在的抗2型糖尿病药物新靶点

真核细胞中的内质网是蛋白质合成、翻译和转运的场所,当内质网稳态被打破,出现蛋白质折叠障碍或错误折叠,并导致蛋白质过度积累时,便会引发内质网应激反应,即未折叠蛋白反应。大量的研究表明,内质网应激与2型糖尿病的病理特征有一定的关系,而转录激活因子6通路作为未折叠蛋白反应中3条信号通路之一,调控着蛋白质的重折叠过程,对缓解内质网应激以及在糖脂代谢和胰岛素敏感性方面起着重要作用。简介内质网应激反应及相关信号通路和转录激活因子6．着重综述转录激活因子6在肝脏糖脂代谢和胰岛素抵抗中的作用及相应机制,探讨其成为抗2型糖尿病药物新靶点的可能性,为抗2型糖尿病药物的研发提供新思路。     

Cigarette smoke extracts induce apoptosis in Raw264.7 cells via endoplasmic reticulum stress and the intracellular Ca2+/P38/STAT1 pathway

Cigarette smoke (CS) exposure is a risk factor for chronic obstructive pulmonary disease (COPD). CS exposure impairs the ability of killing pathogens in macrophages, which might be due to the abnormal apoptosis induced by CS. This study explored the effects and mechanisms of cigarette smoke extract (CSE) on the apoptosis of macrophages in vitro. Raw264.7 cells were treated with CSE at different concentrations, and viability and apoptosis of cells was accessed. The protein expression was detected by western blot. The intracellular Ca²⁺ level was evaluated by Fluo-4 AM probe assay.CSE induced the apoptosis and increased the expression of cleaved caspase 3, which were attenuated by a caspase inhibitor. CSE increased the expression of CHOP, BiP and P-eif2α, and the inhibitor of endoplasmic reticulum stress (ERS) decreased the apoptosis induced by CSE. Phosphorylation levels of P38, JNK and ERK1/2 were increased following incubation with CSE. Only P38 inhibitor significantly reduced apoptosis induced by CSE, while ERK1/2 inhibitor promoted apoptosis. Phosphorylation of STAT1 at Ser727 was activated by CSE and attenuated by the P38 inhibitor. Finally, CSE increased the level of intracellular Ca²⁺, and calcium chelator partly attenuated the apoptosis and phosphorylation of P38 and STAT1 induced by CSE.CSE induced a caspase 3-dependent apoptosis in Raw264.7 cells via ERS and intracellular Ca²⁺/P38/STAT1 pathway.     

Mechanism of testicular protection of carvedilol in streptozotocin-induced diabetic rats

Aims:

Male sub-fertility and infertility are major complications of diabetes mellitus. The non-selective β-blocker carvedilol has been reported to have favorable effects on some of the diabetic complications based on its antioxidant and anti-apoptotic effects. This study aims to evaluate the possible testicular protective effect of carvedilol in streptozotocin (STZ)-induced diabetic rat model and its possible mechanisms.

Materials and Methods:

Diabetes was induced by a single i.p. dose of 65 mg/kg of STZ. In parallel groups of diabetic rats, carvedilol in low and high doses (1 and 10 mg/kg/day orally) were administered for 4 weeks. Oxidative stress markers as reduced glutathione (GSH) and the product of lipid peroxidation; malondialdehyde (MDA) were evaluated in testicular homogenate. The level of expression of the apoptotic marker; caspase 3, was assessed using western blot, followed by densitometric analysis.

Results:

Induction of diabetes caused distortion of histological normal testicular structure, with decrease (P < 0.05) in GSH and increase (P < 0.05) in MDA, as well as induction of caspase 3 expression. Carvedilol in low or high doses reverted diabetes-induced histological damage, restored antioxidant activity and ameliorated caspase 3 expression.

Conclusion:

Carvedilol confers testicular protection against diabetes-induced damage through antioxidant and anti-apoptotic mechanisms.KEY WORDS: Apoptosis, carvedilol, diabetes, oxidative stress, testes     

SREBP-1在1型糖尿病大鼠肾脏的表达和胰岛素的干预性研究

目的探讨1型糖尿病大鼠肾脏脂质沉积和固醇调节元件结合蛋白-1(sterol regulatory element binding protein-1,SREBP-1)的表达以及胰岛素处理的影响。方法以Wistar大鼠建立链脲佐菌素1型糖尿病模型并随机分为正常对照组,糖尿病模型组和胰岛素处理组。喂养2 wk后处死,测定肾皮质组织甘油三酯含量,油红O染色检测脂质沉积的部位;免疫组织化学、Western blot和原位杂交检测肾脏SREBP-1表达。结果与正常对照组相比,1型糖尿病大鼠肾脏甘油三酯含量明显升高,油红O检测示脂质沉积定位于肾近曲小管上皮细胞,肾小球内未见着色。胰岛素处理明显降低了甘油三酯含量,和糖尿病模型组相比差异有统计学意义。免疫组织化学检测SREBP-1定位于大鼠肾脏近曲小管上皮细胞胞质,糖尿病组表达量明显高于正常组和胰岛素处理组。Western blot证实了SREBP-1蛋白前体片段和成熟片段在糖尿病组的高表达,前体片段积分光密度比值为0.673±0.027,成熟片段为0.670±0.028,分别是正常组的1.86倍和1.77倍;胰岛素处理后SREBP-1蛋白前体片段表达下降了52.8%,成熟片段表达量下降了30.9%。原位杂交结果证实SREBP-1 mRNA定位于近曲小管上皮细胞胞质,糖尿病组表达明显升高,与正常对照组相比差异有统计学意义(P<0.01);胰岛素处理后其表达明显下降。结论1型糖尿病大鼠肾近曲小管上皮细胞SREBP-1 mRNA和蛋白表达升高可能参与了肾脏脂质沉积,胰岛素处理可有效降低SREBP-1mRNA和蛋白表达。     

牛磺酸对2型糖尿病大鼠胰腺线粒体氧化应激的影响

目的探讨牛磺酸对糖尿病大鼠胰腺线粒体氧化应激的影响。方法将30只Wistar大鼠随机分为正常对照组、糖尿病组(DM组)和牛磺酸治疗组(Tau组,采用20g.L-1牛磺酸生理盐水溶液治疗,200mg·kg-1),前两组注射等体积的生理盐水溶液。8wk后,测3组大鼠血浆葡萄糖、胰岛素、丙二醛(MDA),胰腺线粒体MDA、Ca2+、超氧化物歧化酶(SOD)及Na+,K+-ATP酶(Na+,K+-ATPase)和Ca2+,Mg2+-ATP酶(Ca2+,Mg2+-ATPase)的活性。结果①DM组大鼠血糖、MDA和胰腺线粒体MDA、Ca2+含量明显高于对照组(P<0.01),而血浆胰岛素水平、SOD、Na+,K+-AT-Pase和Ca2+,Mg2+-ATPase活性明显降低(P<0.05)。②Tau组大鼠血糖、MDA及胰腺线粒体Ca2+、MDA含量较DM组明显降低(P<0.05),血浆胰岛素水平、SOD、Na+,K+-ATPase和Ca2+,Mg2+-ATPase活性明显升高(P<0.05)。结论牛磺酸可减轻2型糖尿病大鼠胰腺线粒体氧化应激水平。     

Treatment of the patient with diabetes: importance of maintaining target HbA1c levels

SUMMARY

Objective: To review clinical trial evidence supporting treatment of patients to a near-normal HbA_1c target level and outline therapeutic strategies that optimize glycemic control.

Research design and methods: The current MEDLINE database and bibliographies were searched for literature relevant to diabetic complications, glycemic control, and the intensive management of diabetes mellitus.

Results: Two randomized trials, the Diabetes Control and Complications Trial and the UK Prospective Diabetes Study (UKPDS), provided evidence that intensive glycemic control obtained with either intensive insulin or oral therapy effectively slowed the onset and progression of diabetic retinopathy, nephropathy, and neuropathy in patients with type 1 and type 2 diabetes. An epidemiologic analysis of the UKPDS results showed a significant correlation between glycemic control and microvascular and cardiovascular disease risk and mortality rates.

Conclusions: The results of clinical trials confirm that stringent levels of glycemic control can be attained through the use of intensive multiple-injection insulin regimens (administration of insulin 3 or more times daily by injection or an external pump with dosage adjustments as needed), oral monotherapy or combination therapy, or a combination of insulin and oral therapy. The expanded choices for oral agents and the availability of insulin analogs now provide physicians with the tools to tailor therapy to prevent or delay the devastating complications of diabetes. Indeed, newer insulin analogs, both short-acting (insulin lispro, insulin aspart) and long-acting (insulin glargine), are an important part of a treatment strategy to circumvent diabetes complications and overcome the shortcomings of conventional insulin preparations.     

Jiedutongluotiaogan formula restores pancreatic function by suppressing excessive autophagy and endoplasmic reticulum stress

ContextJiedutongluotiaogan formula (JTTF), a traditional Chinese medicine (TCM), could promote islet function. However, the potential effect of JTTF on endoplasmic reticulum stress (ERS) and autophagy have not been reported.ObjectiveThis study explores the potential effect of JTTF on ERS and autophagy in the pancreas.Materials and methodsThe Zucker diabetic fatty (ZDF) rats were randomised into five groups, control, model, JTTF (1, 3, 5 g/kg/day for 12 weeks). LPS induced pancreatic β-cells were treated with JTTF (50, 100, 200 μg/mL). LPS was used to induce pancreatic β-cell injury, with cell viability and insulin secretion evaluated using MTT, glucose-stimulated insulin secretion (GSIS) assays, and PCR. Intracellular Ca²⁺ concentration was measured using flow cytometry, while ERS and autophagy levels were monitored via Western blotting and/or immunostaining.ResultsCompared with the model group, body weight, FGB, HbA1c, IPGTT, FINs, and HOMA-IR in JTTF treatment groups were significantly reduced. In islets cells treated with JTTF, the pancreatic islet cells in the JTTF group were increased, lipid droplets were reduced, and there was a decrease in Ca²⁺ (16.67%). After JTTF intervention, PERK, p-PERK, IRE1α, p- IRE1α, ATF6, eIF2α, GRP78, p-ULK1, LC3 and p62 expression decreased, whereas Beclin1and p-mTOR expression increased. In addition, the expression of proteins related to apoptosis in the JTTF groups were lower than those in the control group.Discussion and conclusionsJTTF may alleviate pancreatic β-cell injury by inhibiting ER stress and excessive autophagy in diabetic rats. This provides a new direction for treating diabetes and restoring pancreatic dysfunction by TCM.     

Combination lipid therapy in type 2 diabetes mellitus

Introduction: A significant drop in cardiovascular risk has been seen in patients with type 2 diabetes treated with statins. However, this cardiovascular risk remains high, compared with nondiabetic individuals. This is partly due to the typical abnormalities of diabetic dyslipidemia – hypertriglyceridemia and decreased high-density lipoprotein cholesterol (HDL-C) – that are uncontrolled by statins. For this reason, combination lipid therapy may be considered in patients with type 2 diabetes.

Areas covered: This review presents the main reasons for a combination lipid therapy in type 2 diabetes and the effects of several drugs, including fibrates, pioglitazone, niacin and omega 3, on diabetic dyslipidemia and the prevention of cardiovascular events. The real cardiovascular benefit of fibrates in patients with type 2 diabetes is not totally clear, but they may produce a significant benefit in patients with type 2 diabetes and diabetic dyslipidemia (hypertriglyceridemia, low HDL-C). Pioglitazone, which reduces triglycerides and increases HDL-C, has been shown to reduce the risk for major cardiovascular events in type 2 diabetes. Niacin and omega 3 fatty acids have a positive effect on diabetic dyslipidemia, but warrants clinical trials to demonstrate a clear cardiovascular benefit in type 2 diabetes.

Expert opinion: Although combination lipid therapy seems to be useful to control diabetic dyslipidemia, the efficacy of such combined therapies on significantly reducing cardiovascular risk has still to be confirmed by additional clinical trials.     

Pharmacokinetic drug evaluation of empagliflozin plus linagliptin for the treatment of type 2 diabetes

Introduction: Type 2 diabetes mellitus has become a growing epidemic and therefore efficient treatment strategies that target its management are needed. The treatment of diabetic patients often requires the combination of antidiabetic drug classes. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) block glucose reabsorption in the proximal renal tubules. Dipeptidyl peptidase-4 inhibitors (DPP-4i) improve glucose metabolism by blocking the enzyme that degrades incretins leading to increased insulin secretion.

Areas covered: The aim of the review is to present the available data on pharmacokinetic properties/pharmacodynamics, metabolic and cardiovascular effects of empagliflozin plus linagliptin combination.

Expert opinion: Both empagliflozin and linagliptin have established safety and efficacy in the treatment of diabetes. Available data demonstrate the absence of pharmacological interactions when the two drugs are given together. The complementary mechanisms of action would be expected to provide additive benefits on carbohydrate metabolism variables, but the results from clinical trials have shown that the empagliflozin/linagliptin combination provides only mild improvements of glycated hemoglobin compared with either monotherapy. However, the single-tablet formulation of empagliflozin/linagliptin is expected to provide better compliance and thus improved glycaemic control coupled with a favourable safety profile. Thus, the fixed-dose combination of empagliflozin/linagliptin has the capacity to both effectively and safely manage diabetic patients.     

Evaluation of the potential for steady-state pharmacokinetic and pharmacodynamic interactions between the DPP-4 inhibitor linagliptin and metformin in healthy subjects

ABSTRACT

Objective: Linagliptin (BI 1356) is a novel, orally available inhibitor of dipeptidyl peptidase-4 (DPP-4). Linagliptin improves glycaemic control in type 2 diabetic patients by increasing the half-life of the incretin hormone glucagon-like peptide-1 (GLP-1). Linagliptin is expected to be used as monotherapy or in combination with other antihyperglycaemic agents. This study was conducted to investigate potential pharmacokinetic or pharmacodynamic interactions between linagliptin and metformin.

Methods: This randomised, monocentric, open-label, two-way crossover design study was conducted in 16 healthy male subjects. Linagliptin (10?mg/day)?and metformin (850?mg three times daily) were each administered alone and concomitantly. The steady-state pharmacokinetics of linagliptin and metformin and the inhibition of DPP-4 activity were determined at the end of each dosing period.

Results: Co-administration of linagliptin had no apparent effect on metformin exposure (metformin AUC_τ,ss; geometric mean ratio [GMR] co-administration:individual administration was 1.01; 90% confidence interval [CI] was 0.89–1.14). Effects on maximum concentration (C_max,ss) were small (GMR: 0.89; 90% CI: 0.78–1.00). Co-administration of metformin did not significantly affect C_max,ss of linagliptin (GMR: 1.03; 90% CI: 0.86–1.24), but increased AUC_τ,ss by 20% (GMR: 1.20; 90% CI: 1.07–1.34). Metformin alone had no effect on DPP-4 activity, and the inhibition of DPP-4 caused by linagliptin was not affected by concomitant administration of metformin. Tolerability was good whether linagliptin and metformin were administered alone or concomitantly. No serious adverse events occurred and the frequency of adverse events was low; 7 events in 6 subjects. The most frequent events were related to the gastrointestinal tract, as expected with metformin. Importantly, no subjects experienced signs or symptoms relating to episodes of hypoglycaemia.

Conclusion: In this small, multiple dose study carried out in healthy subjects, co-administration of linagliptin with metformin did not have a clinically relevant effect on the pharmacokinetics or pharmacodynamics of either agent. This study suggests linagliptin and metformin can safely be administered concomitantly in type 2 diabetes patients without dose adjustment; larger, longer-term clinical trials in diabetic patients are underway.     

Nickel sulfate induced apoptosis via activating ROS‐dependent mitochondria and endoplasmic reticulum stress pathways in rat Leydig cells

Nickel can induce apoptosis of testicular Leydig cells in mice, whereas the mechanisms remain unclear. In this study, we investigated the role of nickel‐induced reactive oxygen species (ROS) generation in mitochondria and endoplasmic reticulum stress (ERS) mediated apoptosis pathways in rat Leydig cells. Fluorescent DCF and Annexin‐V FITC/PI staining were performed to measure the production of ROS and apoptosis in Leydig cells. RT‐qPCR and Western blot were conducted to analyze the key genes and proteins involved in mitochondria and ERS apoptotic pathways. The results showed that nickel sulfate induced ROS generation, consequently resulted in nucleolus deformation and apoptosis in testicular Leydig cells, which were then attenuated by ROS inhibitors of N‐acetylcysteine (NAC) and 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO). Nickel sulfate‐triggered Leydig cells apoptosis via mitochondria and ERS pathways was characterized by the upregulated mRNA and proteins expression of Bak, cytochrome c, caspase 9, caspase 3, GRP78, GADD153, and caspase 12, which were inhibited by NAC and TEMPO respectively. The findings indicated that nickel‐induced ROS generation was involved in apoptosis via mitochondria and ERS pathways in rat Leydig cells.     

Insulin therapy in type 2 diabetes: insulin analogue mix 50, a potential role in reducing postprandial hyperglycaemia and cardiovascular disease

Importance of the field: Postprandial hyperglycaemia is becoming topical, with studies suggesting a link to cardiovascular disease. Recently, a number of new therapies for the treatment of type 2 diabetes have become available.

Areas covered in this review: This review looks at the evidence for the potential role of insulin analogue mix 50 to reduce postprandial hyperglycaemia and cardiovascular disease. Search Strategy: Medline and Embase databases were searched using the MeSH terms to identify relevant studies from 1980 to 2009. Both original articles and reviews were extracted. Published reference lists were also examined. MeSH terms used for literature searching: human insulins, insulin analogues, insulin analogue mix 50, glycaemia, postprandial glucose, fasting glucose, type 2 diabetes, type 1 diabetes, cardiovascular disease.

What the reader will gain: The reader is presented with evidence discussing the importance of postprandial hyperglycaemia and studies comparing different insulin regimes and in particular insulin analogue mix 50 and its potential to reduce postprandial glucose surges and reduce cardiovascular disease.

Take-home message: Insulin analogue mix 50 is a viable therapeutic option in a sub-group of patients with type 2 diabetes.     

Ras inhibition attenuates pancreatic cell death and experimental type 1 diabetes: Possible role of regulatory T cells

Regulatory T cells (Treg) play a crucial role in the maintenance of immune homeostasis and prevention of autoimmune diseases. Ras inhibition by 5-fluoro-farnesylthiosalicylic acid (F-FTS) was recently shown to increase the number and boost the suppressive function of Treg, thereby reducing the incidence of experimental diabetes in non-obese diabetic (NOD) mice. To investigate the effect of F-FTS on pancreatic beta cells and the possible involvement of Treg in such an effect, we evaluated the incidence of diabetes and assayed the pancreatic expression of Foxp3, cleaved caspase 3, and Ras-GTP expression in NOD mice treated with different doses of F-FTS. The treated mice showed attenuated progression of experimental diabetes, accompanied by an increase in serum insulin. Daily injections of F-FTS led to an increase in both the number and the migratory capacity of pancreatic Foxp3⁺CD4⁺CD25⁺ Treg, while cleaved caspase 3 in the pancreas were significantly decreased, indicating reduced apoptosis. The Treg population induced by F-FTS helped to preserve pancreatic beta-cell viability in the presence of effector T cells. These findings suggest that inhibition of Ras by F-FTS in mice with experimental diabetes upregulates the Treg pool, which infiltrates the pancreas and attenuates the apoptotic cell death of beta cells. It thus appears that F-FTS induces Treg to play a protective role in the progression of experimental type-1 diabetes, suggesting that these cells represent a potential target for the treatment of this disorder.     

Effects of diabetes on murine lipoproteins and vascular disease

The creation of mouse models that recapitulate human diabetic cardiovascular disease remains a significant challenge. Part of the problem relates to the lack of a clear understanding of the human phenotype. Although improved insulin-treat of hyperglycemia reduces cardiovascular events in patients with type 1 diabetes, similar data are not available in type 2 diabetes. Moreover, whether human vascular disease is increased by hyperglycemia, defective insulin actions, or other factors is not known. Significant progress has been made in developing models of both type 1 and type 2 diabetes in mouse that can be used to study the relationship between hyperglycemia and atherosclerosis. This review describes mouse models that recapitulate specific aspects of diabetic dyslipidemia, hyperglycemia/insulin resistance, and diabetic vascular disease. Overall, the studies have clearly demonstrated that hyperlipidemia is a major driver of atherosclerotic vascular disease in the mouse. The effects of hyperglycemia and insulin resistance on murine atherosclerosis remain uncertain.     

Vascular protection of DPP-4 inhibitors in retinal endothelial cells in in vitro culture

People with diabetes are at high risk of developing diabetes-related eye disease, termed as diabetic retinopathy, due damage being caused to the blood vessels in the retina. An efficient medical treatment to reduce diabetic retinopathy can improve the quality of life for diabetes patients. In our study, we show that linagliptin, a commercially available DPP-4 inhibitor, plays a protective role in retinal vascular endothelial cells. The presence of linagliptin protects retinal endothelial cells against TNF-α-induced cytotoxicity and enhances their viability. Linagliptin treatment suppresses TNF-α-induced production of reactive oxygen species and improves mitochondrial membrane potential. Moreover, linagliptin suppresses TNF-α-induced production of pro-inflammatory and pro-adhesive vascular cytokines including IL-6, IL-8, ICAM-1, and VCAM-1. The presence of linagliptin in cell media can reduce the number of THP-1 cells that adhere to retina endothelial cells. Mechanistically, linagliptin potently suppresses TNF-α-induced accumulation of NF-κB nuclear protein p65 and activation of NF-κB promoter. Our data indicate that linagliptin is an anti-inflammatory diabetic agent, with the potential to be applied as a treatment for diabetic retinopathy.     

Cardiovascular effects of sitagliptin – An anti‐diabetes medicine

Dipeptidyl‐peptidase‐4 (DPP‐4) inhibitors, as the most recent available anti‐diabetic agents, were generally used in clinical treatment of type 2 diabetes (T2DM). In addition to anti‐diabetic effects, the five most widely used DPP‐4 inhibitors (sitagliptin, vildagliptin, saxagliptin, linagliptin and alogliptin) also exert cardiovascular protective effects. In recent years, increasing studies suggest that sitagliptin shows pleiotropic impacts towards the cardiovascular system either with or without diabetes. In this review, we summarized the recent reports to provide an update discussion about cardiovascular protective effects of sitagliptin and the corresponding mechanisms. Sitagliptin has positive effects towards ischaemic cardiovascular diseases, atherosclerosis and hypertension. These effects are mainly conducted through DPP‐4 inhibitions. In addition, sitagliptin exerts anti‐inflammation, anti‐oxidative stress, anti‐apoptosis, mediation on lipid accumulation and so on, which also contribute to its cardiovascular effects.     

Cardiovascular complications of non-insulin-dependent diabetes: the JCR:LA-cp rat

Diabetes is a serious medical and financial burden on western societies. It is the seventh leading cause of death in the United States and Canada. The disease is due to a primary defect in glucose tolerance and carbohydrate metabolism resulting from either a deficiency of insulin (Insulin-dependent (type I) diabetes mellitus - IDDM) or a state of insulin resistance (Non-insulin-dependent (type II) diabetes mellitus - NIDDM). NIDDM comprises greater than 80% of total diabetic cases. Associated with the primary metabolic defects are equally deleterious secondary complications affecting the renal, ocular, nervous and cardiovascular systems. The cardiovascular complications account for a major proportion of diabetic mortality. As such, it is of paramount importance to develop or find an animal model expressing complications homologous to the human condition. Many models of NIDDM are available to the diabetic researcher but choosing an accurate one can be difficult. The following compares the advantages and limitations of one such model, the JCR:LA-cp rat to other NIDDM models commonly used today.     

Linagliptin: a review of its use in the management of type 2 diabetes mellitus

Linagliptin (Trajenta?, Tradjenta?, Trazenta?, Trayenta?) is an oral, highly selective inhibitor of dipeptidyl peptidase-4 and is the first agent of its class to be eliminated predominantly via a nonrenal route. Linagliptin is indicated for once-daily use for the treatment of adults with type 2 diabetes mellitus, and a twice-daily fixed-dose combination of linagliptin/metformin (Jentadueto?) is also available. In this article, the pharmacological, clinical efficacy and tolerability data relevant to the use of linagliptin in patients with type 2 diabetes are reviewed. The efficacy of oral linagliptin in the treatment of adults with type 2 diabetes has been investigated in several double-blind, multicentre trials. Following 12-24 weeks of treatment, improvements in glycaemic control parameters, including glycosylated haemoglobin (HbA(1c); primary endpoint in all trials), were seen with linagliptin relative to placebo when used as monotherapy, initial combination therapy (with metformin or pioglitazone) or add-on therapy to other oral antihyperglycaemia agents (metformin and/or a sulfonylurea) or basal insulin (with or without metformin and/or pioglitazone). In terms of lowering HbA(1c), linagliptin was more effective than voglibose in a 26-week monotherapy trial and noninferior to glimepiride when used as add-on therapy to metformin in a 104-week study. Additional trials and subgroup analyses of pooled data suggest that linagliptin improves glycaemic control regardless of factors such as age, duration of type 2 diabetes, ethnicity and renal function, and as linagliptin is eliminated primarily via a nonrenal route, it can be used without dosage adjustment in patients with renal impairment of any degree. Oral linagliptin was generally well tolerated and was associated with a low likelihood of hypoglycaemia (except when used in combination with a sulfonylurea) and had little effect on bodyweight. Further long-term and comparative efficacy and tolerability data are required to help position linagliptin more definitively with respect to other antihyperglycaemia agents. However, clinical data currently available indicate that linagliptin is an effective and generally well tolerated treatment option for use in patients with type 2 diabetes, including those with renal impairment for whom other antihyperglycaemia agents require dosage adjustment or are not suitable.     

桑枝多糖对糖尿病模型小鼠的降血糖作用

目的研究桑枝多糖对糖尿病小鼠的降血糖作用,并探讨其作用机制。方法采用ip给予链脲佐菌素结合饲喂高能高脂饲料的方法,制备糖尿病小鼠模型。糖尿病模型小鼠ig给予桑枝多糖200,400和600 mg·kg-1,每天1次,连续4周。葡萄糖氧化酶法测定血糖水平,分光光度法测定血清超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,比色法测定肝糖原水平,甘油磷酸氧化酶法测定血清甘油三酯(TG)水平,酶法测定血清总胆固醇(TCH)水平,ELISA法测定血清胰岛素水平。结果桑枝多糖能显著降低糖尿病模型小鼠血糖浓度,与给药前相比,给药4周后桑枝多糖400和600 mg·kg-1组血糖浓度分别下降了33.3%和29.9%(P<0.05);与模型组相比,桑枝多糖400和600 mg·kg-1组分别下降了40.4%和38.8%(P<0.01),200 mg·kg-1组下降了34.6%(P<0.05)。与模型组相比,桑枝多糖可显著升高血清SOD活性(P<0.01),降低血清TG含量(P<0.01),降低血清TCH和MDA含量(P<0.05,P<0.01),增加肝糖原存储量(P<0.05);桑枝多糖能显著提高血清胰岛素水平和机体胰岛素敏感性(P<0.01,P<0.05)。结论桑枝多糖对糖尿病模型小鼠具有降血糖作用,其作用机制可能与其增强机体清除自由基和抗脂质过氧化能力、调节脂类物质代谢、增加肝糖原存储量、改善机体的胰岛素分泌及对胰岛素的增敏性等有关。