Back-regulation of six oxidative stress proteins with grape seed proanthocyanidin extracts in rat diabetic nephropathy

Diabetic nephropathy (DN) is a major cause of morbidity and mortality in diabetic patients. To prevent the development of this disease and to improve advanced kidney injury, effective therapies directed toward the key molecular target are required. Grape seed proanthocyanidin extracts (GSPE) have been reported to be effective in treating DN, while little is known about the functional protein changes. In this study, we used streptozotocin (STZ) to induce diabetic rats. GSPE (250 mg/kg body weight/day) were administrated to diabetic rats for 24 weeks. Serum glucose, glycated hemoglobin, and advanced glycation end products were determined. Consequently, 2-D difference gel electrophoresis and mass spectrometry were used to investigate kidney protein profiles among the control, untreated and GSPE treated diabetic rats. Twenty-five proteins were found either up-regulated or down-regulated in the kidneys of untreated diabetic rats. Only nine proteins in the kidneys of diabetic rats were found to be back-regulated to normal levels after GSPE therapy. These back-regulated proteins are involved in oxidative stress, glycosylation damage, and amino acids metabolism. Our findings might help to better understanding of the mechanism of DN, and provide novel targets for estimating the effects of GSPE therapy.     

AD-MSCs and BM-MSCs Ameliorating Effects on The Metabolic and Hepato-renal Abnormalities in Type 1 Diabetic Rats

Diabetes mellitus (DM) is one of the most serious threats in the 21th century throughout the human population that needs to be addressed cautiously. Nowadays, stem cell injection is considered among the most promising protocols for DM therapy; owing to its marked tissues and organs repair capability. Therefore, our 4 weeks study was undertaken to elucidate the probable beneficial effects of two types of adult mesenchymal stem cells (MSCs) on metabolism disturbance and some tissue function defects in diabetic rats. Animals were classified into 4 groups; the control group, the diabetic group, the diabetic group received a single dose of adipose tissue-derived MSCs and the diabetic group received a single dose of bone marrow-derived MSCs. Herein, both MSCs treated groups markedly reduced hyperglycemia resulting from diabetes induction via lowering serum glucose and rising insulin and C-peptide levels, compared to the diabetic group. Moreover, the increased lipid fractions levels were reverted back to near normal values as a consequence to MSCs injection compared to the diabetic untreated rats. Furthermore, both MSCs types were found to have hepato-renal protective effects indicated through the decreased serum levels of both liver and kidney functions markers in the treated diabetic rats. Taken together, our results highlighted the therapeutic benefits of both MSCs types in alleviating metabolic anomalies and hepato-renal diabetic complications.     

Influence of sex,strain, and species on trace metal status of insulin-deficient diabetic rodents

Previous studies have demonstrated marked alterations in trace metal metabolism in male Sprague-Dawley rats following chemical induction of the diabetic state. To determine whether such changes represented a general response to the insulin-deficient condition the levels of zinc, copper, and maganese in liver, kidney, and intestine of normal and streptozotocin (STZ)-diabetic male rats of the Sprague-Dawley, Wistar, and Long-Evans strains, female Sprague-Dawley rats, and male mice were measured. Significantly increased concentrations of zinc, copper, and maganese in liver, and zinc and copper in kidney were found in STZ-diabetic rats, regardless of sex and strain. In contrast, the zinc and copper contents in liver and kidney of control and STZ-diabetic mice were similar, but hepatic manganese levels were significantly elevated in both organs of the diabetic mouse. The concentrations of all three metals were similar in the intestine of control and diabetic rodents. Higher amounts of zinc and copper were bound to metallothionein in the liver and kidney of the diabetic rats. Nicotinamide injection prior to STZ administration protected rats against the development of diabetes and alterations in trace metal status. These data indicate that specific alterations in the metabolism of zinc, copper and manganese during episodes of pancreatic hormonal imbalance represent a general phenomenon in the rat. A possible explanation for the differential response of the STZ-diabetic mouse is discussed.     

Influences of crude extract of tea leaves,Camellia sinensis,on streptozotocin diabetic male albino mice

Natural remedies from medicinal plants are considered to be effective and safe alternative treatment for diabetes mellitus. The aim of the present study was to investigate the hypoglycemic activity of the crude tea leaves extract on streptozotocin (STZ)-induced diabetic mice. The average body weight of animals with diabetes and their percentage changes of body weight gain after 15 and 30 days were significantly lower than that of the normal control mice. In diabetic mice, supplementation with tea leaves extract decreased the loss of body weight. After 15 and 30 days, significant increases in the levels of serum glucose, triglycerides, cholesterol, creatinine, urea, uric acid, glutamic pyruvic acid transaminase (GPT) and glutamic oxaloacetic acid transaminase (GOT) were noted in STZ-diabetic mice fed with normal diet. Also, the values of total protein in this group were statistically declined after 15 and 30 days. The levels of serum glucose and GPT were significantly elevated after 15 and 30 days in diabetic mice supplemented with tea leaves extract. Moreover, the level of serum GOT was notably increased after 30 days. Insignificant alterations were observed in the levels of serum triglycerides, cholesterol, total protein, creatinine, urea and uric acid in diabetic mice supplemented with tea leaves extract. Thus, the present results have shown that tea leaves extract has the antihyperglycemic, antihyperlipidemic, and antihyperproteinemic effects and consequently may alleviate liver and kidney damage associated with STZ-induced diabetes in mice.     

Differential expression of proteins in kidney, eye, aorta, and serum of diabetic and non-diabetic rats

Diabetes mellitus (DM) is a chronic progressive disease that often results in microvascular and macrovascular complications, yet its pathogenesis is not clear. Automated proteomic technology, coupled with powerful bioinformatics and statistical tools, can provide new insights into the molecular alterations implicated in DM. Following our previous findings of redox changes in the eye and aorta of diabetic rats, as well as the activities of different antioxidant enzymes during the development of DM, this study is further launched to find potential biomarkers by comparing the serum and tissue samples of 26 diabetic rats (8 weeks after streptozotocin [STZ] administration) with 29 normal controls using surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) technology. Eight potential biomarkers were found in the serum, one potential biomarker was found in the kidney and eye, respectively, whereas three potential biomarkers were discovered in the aorta. One of the serum biomarker candidates was found to match the C-reactive protein (CRP) in the Swiss-Prot knowledgebase. Further validation has been conducted by ELISA kit to confirm the role of CRP during the development of DM. To conclude, the increased level of CRP in diabetic serum demonstrated in this study indicates that the development of DM is associated with inflammation. This is also the first report demonstrating that some potential lysate biomarkers in the kidney, eye, and aorta may be involved in the development of diabetes and its complications. Further identification and evaluation of these potential biomarkers will help unravel the underlying mechanisms of the disease.     

Effect of FeSO4 treatment on glucose metabolism in diabetic rats

Iron, the prosthetic group of haemoglobin, was found to lower serum glucose levels of diabetic rats. Its regulative mechanism and effects on enzymatic activities of glucose metabolism are still unknown. In this study, the correlation between iron supply and enzymatic activities of glucose metabolism and respiratory chain were evaluated in liver and kidney tissues of alloxan induced-diabetic rats. After FeSO₄ and metformin administration, serum samples were collected for serum glucose and fructosamine level measurements. Kidney and liver tissues were excised at the end of the study for assaying enzymatic activities of isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, NADH-dehydrogenase and cytochrome-c-oxidase. Results showed significantly decreased serum glucose and fructosamine levels in treatment groups and enhanced enzymatic activities of several proteins as compared with the diabetic control group. Therefore, these data suggested that FeSO₄ administration could increase the supply of oxygen, enhance enzymatic activities of glucose metabolism and the respiratory chain, accelerate glucose metabolism and consequently decrease serum glucose levels.     

Adiponectin gene therapy of streptozotocin-induced diabetic mice using hydrodynamic injection

BACKGROUND: Adiponectin (Adipo), an adipocyte hormone involved in the regulation of glucose and lipid metabolism, has already been identified as a potential therapeutic target for the treatment of diabetes. However, successful delivery of Adipo to the receptors is difficult due to their peptide characteristics. Receptors for Adipo are abundantly expressed in the liver and skeletal muscle. METHODS: Uptake of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) in hepatoblastoma HepG2 cells expressing Adipo was examined. Adipo-expressing plasmid DNA (10-50 microg) in saline solution (0.1 ml/g body weight) was rapidly injected into the tail vein of 4-week-old diabetic mice after 4-6 weeks of treatment with streptozotocin (STZ). Uptake of glucose in diabetic mice also was measured using a planar positron imaging system featuring 18-fluorodeoxyglucose. RESULTS: HepG2 cells expressing Adipo exhibited significantly increased 2-NBDG uptake compared with cells transfected with control plasmid even in the absence of insulin. STZ-induced diabetic mice showed decreased serum Adipo levels compared with non-diabetic mice. A single hydrodynamic injection of 10-50 microg Adipo-expressing plasmid DNA into diabetic mice led to approximately 10-15-fold elevation in serum Adipo levels, and resulted in decreased serum levels of glucose and triglyceride. As well as exhibiting higher levels of Adipo expression, diabetic mice also had higher hepatic glucose uptake than similar mice injected with control plasmid. CONCLUSIONS: We report that STZ-induced diabetic mice exhibited decreased Adipo levels and hyperglycemia which may be alleviated by hydrodynamic injection of the Adipo gene. This type of gene delivery system to the liver offers a different approach in developing novel treatments for type 1 and 2 diabetes.     

Diosmetin ameliorate type 2 diabetic mellitus by up-regulating Corynebacterium glutamicum to regulate IRS/PI3K/AKT-mediated glucose metabolism disorder in KK-Ay mice

Background and purposeDiosmetin (Dios), a flavonoid compound with multiple pharmacological activities. However, fewer studies have reported its effects on type 2 diabetic mellitus (T2DM). Here, we address the effect of Dios on glucose metabolism and gut microbiota in KK-Ay diabetic mice.MethodWild type C57BL/6 J mice or diabetic KK-Ay mice were treated with vehicle or Dios for one month. The ELISA kit and fluorescence microscope system were respectively employed to the evaluation of serum biochemical indicators and histopathological changes. Liver RNA-Seq and western blot were used to reveal the key signaling pathway. The effects of Dios on gut microbiota was investigated by the 16S rRNA gene sequencing, as well as the relationship between Dios and C. glu on glucose metabolism was explored with the C. glu transplantation.ResultsDios treatment significantly decreased blood glucose and increased serum insulin concentrations. RNA-Seq analysis found that the underlying action mechanism of Dios on T2DM was via modulating glucose metabolism, which was proved by up-regulating IRS/PI3K/AKT signaling pathway to promote glycogen synthesis and GLUT4 translocation. Besides, Dios treatment reshaped the unbalanced gut microbiota by suppressing the ratio of Firmicutes/Bacteroidetes and markedly increasing the richness of C. glu. Moreover, treatment with C. glu and Dios together could markedly ameliorate glucose metabolism by up-regulating IRS/PI3K/AKT signaling pathway to promote glycogen synthesis and GLUT4 translocation.ConclusionsDios treatment remarkably ameliorated glucose metabolism in KK-Ay diabetic mice by the regulation of C. glu via IRS/PI3K/AKT signaling pathway and reshaped the unbalanced gut microbiota. Our study provided evidence for the application of Dios to the treatment of T2DM.     

Spider silk fibroin enhances insulin secretion and reduces blood glucose levels in diabetic mice

Fibroin silk proteins make up the cocoons of silkworms and spider webs and are rich in glycine and alanine residues. Recent studies have shown that silk fibroin hydrolysate from silkworms improves blood glucose and lipid metabolism. In the present study, we investigated the anti-diabetic effects of spider silk fibroin protein in type 2 diabetic mice. Recombinant AvMaSp-R, which consists of the 240 amino acid repetitive domain of major ampullate silk protein (AvMaSp) from the spider Araneus ventricosus, was produced in baculovirus-infected insect cells. We tested the effects of oral AvMaSp-R administration on serum insulin and blood glucose levels in diabetic mice and found that AvMaSp-R increases serum insulin levels and reduces blood glucose levels in diabetic mice. Consequently, our results are the first to provide evidence that silk fibroin protein from spiders enhances insulin secretion, which leads to reduced blood glucose levels in type 2 diabetic mice.     

Influence of alloxan-induced diabetes and selenite treatment on blood glucose and glutathione levels in mice

Many clinical studies reported that diabetic patients had lower glutathione contents in erythrocytes or plasma. Recently, selenium, an essential trace element with well-known antioxidant characteristics, has been found to have insulin-mimetic properties. But seldom information is available about the influence of selenium on glutathione changes induced by diabetes mellitus in animals. Therefore, this study was designed to compare the impacts of selenite treatment on glutathione (GSH) levels of blood and tissues such as brain, kidney, liver, spleen and testis in mice. Four groups were used in this study: a control group, a diabetic group, a selenite-treated normal group and a selenite-treated diabetic group. Selenite was administered to the mice for 4 weeks with an oral dose of 2 mg kg(-1) day(-1) by gavage. The blood glucose level, and GSH level in blood and tissues were determined. The results show that the selenite-treated diabetic group had significantly lower blood glucose levels than the diabetic group. Moreover, alloxan-induced diabetes significantly decreased GSH levels in blood, kidney, liver and testis compared to the controls. Selenite treatment of the diabetic mice only improved the GSH levels in liver and brain. On the other hand, selenite administered to the normal mice reduced GSH levels in the liver compared to the controls. In conclusion, this study suggests that selenite treatment of diabetic mice with an effective dose would be beneficial for the antioxidant system of liver and brain although it exerts a toxic effect on the liver of normal mice.     

基因技术在治疗2型糖尿病中的应用*

2型糖尿病(type 2 diabetes mellitus, T2DM)是一类由于胰岛β细胞损伤和机体对胰岛素耐受引发的慢性代谢性疾病,其快速增长的患病率和并发症所带来的高病死率已成为人类面临的医学难题。目前,T2DM主要是以降糖药物及胰岛素增敏剂等药物进行治疗,但是这类药物会产生严重的副作用,而且不能长期良好控制血糖和防止各种慢性并发症。因此,基因治疗是未来医疗发展的主要方向。基因治疗不仅可以靶向调控血糖水平进而提高降糖的效果,而且能够减少糖代谢异常引起的并发症,保护组织器官免受损伤。在认识传统药物治疗糖尿病的基础上,综述了基因技术在治疗T2DM中的应用,讨论了基因技术治疗T2DM的意义及存在的问题。基因技术的应用不仅有利于T2DM的预防和个体化治疗,同时也为糖尿病并发症提供了新的治疗途径。     

Analysis of the effect of a novel therapeutic for type 2 diabetes on the proteome of a muscle cell line

Elevated serum retinol‐binding protein (RBP) concentration has been implicated in the development of insulin resistance and type 2 diabetes. Two series of small molecules have been designed to lower serum levels by reducing secretion of the transthyretin–RBP complex from the liver and enhancing RBP clearance through the kidney. These small molecules were seen to improve glucose and insulin tolerance tests and to reduce body weight gain in mice rendered diabetic through a high fat diet. A proteomics study was conducted to better understand the effects of these compounds in muscle cells, muscle being the primary site for energy expenditure. One lead compound, RTC‐15, is seen to have a significant effect on proteins involved in fat and glucose metabolism. This could indicate that the compound is having a direct effect on muscle tissue to improve energy homeostasis as well as a whole body effect on circulating RBP levels. This newly characterized group of antidiabetic compounds may prove useful in the treatment and prevention of insulin resistance and obesity.     

Abnormal renal, hepatic, and muscle glucose metabolism following glucose ingestion in type 2 diabetes

Recent studies indicate an important role of the kidney in postprandial glucose homeostasis in normal humans. To determine its role in the abnormal postprandial glucose metabolism in type 2 diabetes mellitus (T2DM), we used a combination of the dual-isotope technique and net balance measurements across kidney and skeletal muscle in 10 subjects with T2DM and 10 age-, weight-, and sex-matched nondiabetic volunteers after ingestion of 75 g of glucose. Over the 4.5-h postprandial period, diabetic subjects had increased mean blood glucose levels (14.1 +/- 1.1 vs. 6.2 +/- 0.2 mM, P < 0.001) and increased systemic glucose appearance (100.0 +/- 6.3 vs. 70.0 +/- 3.3 g, P < 0.001). The latter was mainly due to approximately 23 g greater endogenous glucose release (39.8 +/- 5.9 vs. 17.0 +/- 1.8 g, P < 0.002), since systemic appearance of the ingested glucose was increased by only approximately 7 g (60.2 +/- 1.4 vs. 53.0 +/- 2.2 g, P < 0.02). Approximately 40% of the diabetic subjects' increased endogenous glucose release was due to increased renal glucose release (19.6 +/- 3.1 vs. 10.6 +/- 2.4 g, P < 0.05). Postprandial systemic tissue glucose uptake was also increased in the diabetic subjects (82.3 +/- 4.7 vs. 69.8 +/- 3.5 g, P < 0.05), and its distribution was altered; renal glucose uptake was increased (21.0 +/- 3.5 vs. 9.8 +/- 2.3 g, P < 0.03), whereas muscle glucose uptake was normal (18.5 +/- 1.8 vs. 25.9 +/- 3.3 g, P = 0.16). We conclude that, in T2DM, 1) both liver and kidney contribute to postprandial overproduction of glucose, and 2) postprandial renal glucose uptake is increased, resulting in a shift in the relative importance of muscle and kidney for glucose disposal. The latter may provide an explanation for the renal glycogen accumulation characteristic of diabetes mellitus as well as a mechanism by which hyperglycemia may lead to diabetic nephropathy.     

A model for diabetic nephropathy: advantages of the inducible cAMP early repressor transgenic mouse over the streptozotocin-induced diabetic mouse

We have previously found progressive diabetic nephropathy in inducible cAMP early repressor (ICER Igamma) transgenic (Tg) mice. The ICER Igamma Tg mouse is an interesting model of sustained hyperglycemia due to its low production of insulin and insulin-producing beta cells. Here in a longitudinal study we further analyzed diabetic nephropathy and structural and functional alterations in other organs, comparing our model with streptozotocin (STZ)-diabetic model mice. The high-dose STZ-diabetic model showed marked variation in blood glucose levels and severe toxicity of STZ in the liver and kidney. The low-dose STZ-diabetic model showed less toxicity, but the survival rate was very low. STZ-diabetic mice had much more variation of glomerular hypertrophy and sclerosis. Furthermore, non-specific toxicity of STZ or insulin injections to maintain optimal blood glucose levels might have another effect upon the diabetic renal changes. In contrast, ICER Igamma Tg mice exhibited a stable and progressive phenotype of diabetic kidney disease solely due to chronic hyperglycemia without other modulating factors. Thus, ICER Igamma Tg mouse has advantages for examining diabetic renal disease, and offers unique and very different perspectives compared to STZ model.     

AdipoRon对2型糖尿病小鼠肾脏损伤的干预作用

目的：研究脂联素受体激动剂（AdipoRon）对2型糖尿病小鼠肾脏损伤的干预作用。方法：将40只SPF级雄性C57/BL6小鼠随机分为正常对照组（n=10）和实验组（n=30）：实验组给予高糖、高脂饲料喂养,联合腹腔注射小剂量链脲佐菌素（STZ）建立2型糖尿病（T2DM）小鼠模型,再随机分为3组（n=10）：模型对照（DM）组、低剂量AdipoRon治疗（DM+L）组及高剂量AdipoRon治疗（DM+H）组。检测血清中葡萄糖含量的变化;采用酶联免疫法检测小鼠血清中胰岛素受体（INSR）、胰岛素受体底物-1（IRS-1）以及肿瘤坏死因子-α（TNF-α）的蛋白质含量;HE染色镜下观察肾组织形态学变化;实时荧光定量PCR法检测肾组织胰岛素促进因子-1（PDX-1）和胰岛素（insulin）mRNA的表达;Western blot检测肾组织内磷酸化胰岛素受体底物-1（p-IRS-1）蛋白质;ELISA试剂盒检测小鼠血胰岛素含量。结果：病理学检查表明,AdipoRon可减轻2型糖尿病所致小鼠肾脏损伤。与DM组小鼠比较,DM+H组和DM+L组小鼠血糖、TNF-α水平均显著降低（P<0.05）,INSR、IRS-1和p-IRS-1表达显著上升,PDX-1和insulin mRNA表达显著上升（P<0.05,P<0.01）。结论：给予AdipoRon治疗的小鼠血糖和血清TNF-α水平显著降低,INSR,IRS-1和p-IRS-1蛋白质含量,PDX-1和insulin mRNA表达均显著上升,表明AdipoRon对2型糖尿病小鼠肾脏损伤有一定的干预作用。     

Altered glucose homeostasis and hepatic function in obese mice deficient for both kinin receptor genes

The Kallikrein-Kinin System (KKS) has been implicated in several aspects of metabolism, including the regulation of glucose homeostasis and adiposity. Kinins and des-Arg-kinins are the major effectors of this system and promote their effects by binding to two different receptors, the kinin B2 and B1 receptors, respectively. To understand the influence of the KKS on the pathophysiology of obesity and type 2 diabetes (T2DM), we generated an animal model deficient for both kinin receptor genes and leptin (obB1B2KO). Six-month-old obB1B2KO mice showed increased blood glucose levels. Isolated islets of the transgenic animals were more responsive to glucose stimulation releasing greater amounts of insulin, mainly in 3-month-old mice, which was corroborated by elevated serum C-peptide concentrations. Furthermore, they presented hepatomegaly, pronounced steatosis, and increased levels of circulating transaminases. This mouse also demonstrated exacerbated gluconeogenesis during the pyruvate challenge test. The hepatic abnormalities were accompanied by changes in the gene expression of factors linked to glucose and lipid metabolisms in the liver. Thus, we conclude that kinin receptors are important for modulation of insulin secretion and for the preservation of normal glucose levels and hepatic functions in obese mice, suggesting a protective role of the KKS regarding complications associated with obesity and T2DM.