Low-dose Streptozotocin Injection Research Articles

Hyaluronic Acid-Povidone-Iodine Compound Facilitates Diabetic Wound Healing in a Streptozotocin-Induced Diabetes Rodent Model

Sir: We read with great interest the article entitled “Hyaluronic Acid-Povidone-Iodine Compound Facilitates Diabetic Wound Healing in a Streptozotocin-Induced Diabetes Rodent Model” by Dr. Chen et al.,1 published in the May 2019 issue of Plastic and Reconstructive Surgery. The authors found that higher-molecular-weight hyaluronic acid plus povidone-iodine complex dressing could facilitate diabetic wound healing, which provided a new idea for treating diabetic foot ulcer in clinical practice. Inspired by the authors, we would like to express our opinions on the research of diabetic wound healing. The diabetic foot ulcer represents a prevalent complication of diabetes mellitus and it is more common in people with type 2 diabetes.2 Streptozotocin can selectively damage pancreatic β cells and has been reported to induce both insulin-dependent diabetes mellitus (type 1) and non–insulin-dependent diabetes mellitus (type 2). Type 1 was believed to be induced by a single streptozotocin injection, whereas type 2 has to be induced by a low-dose streptozotocin injection following high-fat diet feeding.3 However, in this article, we noticed that the authors used the diabetic animal model induced by a single injection of streptozotocin, which should be interpreted as type 1. Although the blood glucose level was higher than normal, it cannot reflect the characteristics of type 2 diabetes mellitus with insulin resistance and relative insulin deficiency. Thus, the results of this study may need to be further validated on a specific type 2 diabetic animal model. On the other hand, the authors tested some immunohistochemical indices, such as Ki67, CD45, and vascular endothelial growth factor, to explain the effect of higher-molecular-weight hyaluronic acid plus povidone-iodine compound treatment on cellular proliferation, inflammatory response, and angiogenesis. The early sign of diabetic foot ulcer is peripheral sensory neuropathy caused by the damage of tiny blood vessels in the legs. Thus, it would be better to further test indicators such as substance P and nerve growth factor for epidermal and dermal nerve fibers and clarify whether the therapy has some positive effect on modulating nerve fibers in diabetic wounds. All in all, we appreciate that the authors suggest a new method for the treatment of diabetic foot ulcer. The results of this method used in diabetic patients are worth expecting. DISCLOSURE The authors declare that they have no conflicts of interest. No funding was received for this communication. Sisi Luan, M.D.Department of EndocrinologyShandong Provincial Hospital affiliated to Shandong UniverstiySchool of MedicineShandong UniversityJinan, Shandong, China Chenglong Wang, M.D.Department of Aesthetic and Reconstructive Breast SurgeryPlastic Surgery HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing, China

Zhenqing recipe attenuates non-alcoholic fatty liver disease by regulating the SIK1/CRTC2 signaling in experimental diabetic rats

BackgroundAs a compound Chinese medicine, Zhenqing Recipe (ZQR) has been shown to ameliorate hyperglycemia, hyperlipidemia, fatty liver and insulin resistance in patients with diabetes and diabetic rats. In this paper, we further examined the effect of ZQR on diabetes complicated by non-alcoholic fatty liver disease (NAFLD) and the underlying molecular mechanisms.MethodsDiabetic rats with NAFLD were developed by a high-fat diet (HFD) with low-dose streptozotocin (STZ) injection for 4 weeks. These rats were randomly separated into the diabetic model (DM), ZQR, metformin (Met), adenovirus expressing-salt-induced kinase 1 (Ad-SIK1) and adenovirus labeled with green fluorescent protein (Ad-GFP) groups. The effects on hepatic expression of gluconeogenic genes, glycolipid metabolism and pathological changes were subsequently detected.ResultsSerum glucose, triglycerides (TG), total cholesterol (TC) and hepatic TG were reduced in the ZQR group. The histopathological and immunohistochemical changes in the liver and pancreas in the ZQR group were significantly alleviated. The decrease of SIK1 expression was observed in the liver of diabetic rats induced by HFD and STZ. SIK1 overexpression in the liver relieved hyperglycemia, hyperlipidemia and fatty liver. Both the mRNA and protein levels of CREB-regulated transcription co-activator 2 (CRTC2), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) in the liver were drastically reduced, whereas those of SIK1 were markedly increased in the ZQR group compared to levels in the DM group. Compared with the DM group, Ser577 phosphorylation of SIK1 was obviously reduced in the liver, while T182 phosphorylation of SIK1 and S171 phosphorylation of CRTC2 were evidently increased in the Ad-SIK1, Met and ZQR groups.ConclusionsZQR ameliorates hepatic gluconeogenesis and lipid storage in diabetic rats induced by HFD and STZ by activating the SIK1/CRTC2 signaling pathway. Upregulating hepatic SIK1 by ZQR may represent an efficient strategy for treating diabetes with NAFLD.

Effect of garden cress in reducing blood glucose, improving blood lipids, and reducing oxidative stress in a mouse model of diabetes induced by a high-fat diet and streptozotocin.

A mouse model in which diabetes mellitus was induced by low-dose streptozotocin (STZ) injection combined with a high-fat diet was used to study the effect of two water cress (Lepidium savitum) preparations. Diabetic mice were treated with dried cress powder or with water-soluble extracts (tested at two doses), together with proper control groups. The mice were evaluated after 4 weeks of continuous intervention for type 2 diabetic and associated markers. We determined blood glucose, body weight, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), serum insulin levels, and DNA integrity of hepatic cells. The concentrations of malondialdehyde (MDA) and lipid peroxide (LPO) and the activities of four enzymes that are part of the antioxidant defense system were determined in liver samples, as well as gene expression (by semi-quantitative reverse transcription polymerase chain reaction) and enzyme activity of IRS-1, IRS-2, PI3K, AKT-2, and GLUT4. After 4 weeks of intervention, the levels of TC, TG, and LDL cholesterol were significantly (P < 0.5) decreased and HDL cholesterol was significantly increased. Enzyme activities of liver superoxide dismutase, glutathione, glutathione peroxidase, and catalase were significantly increased, whereas MDA and LPO concentrations were significantly reduced. The transcription level of the five genes assessed was increased, with corresponding increases in protein expression. Oral uptake of garden cress can significantly reduce the blood glucose and improve the blood lipid metabolism of diabetic mice. Considerable improvements in the activity of antioxidant defense enzymes were observed in type 2 diabetic mice that improved the body's antioxidant emergency response. © 2019 Society of Chemical Industry.

&lt;p&gt;Alpha-Mangostin Improves Cardiac Hypertrophy and Fibrosis and Associated Biochemical Parameters in High-Fat/High-Glucose Diet and Low-Dose Streptozotocin Injection-Induced Type 2 Diabetic Rats&lt;/p&gt;

PurposeThe aim of present study was to analyze the effect of alpha-mangostin on cardiac hypertrophy and fibrosis and biochemical parameters in high-fat/high-glucose diet and low-dose streptozotocin injection (HF/HG/STZ)-induced type 2 diabetic rats.MethodsDiabetes was induced in male Wistar rats by giving a combination of high-fat/high-glucose (HF/HG) diet for 3 weeks and followed by low-dose streptozotocin intraperitoneal injection (STZ; 35 mg/kg) at Week-3 and the HF/HG diet was continued until 8 weeks. The diabetic rats were then divided into four groups (each, n=6): untreated diabetic group (HF/HG/STZ); diabetic group treated with metformin 200 mg/kg/day (HF/HG/STZ+Metformin); diabetic group treated with alpha-mangostin 100 mg/kg/day (HF/HG/STZ+AM100); and diabetic group treated with alpha-mangostin 200 mg/kg/day (HF/HG/STZ+AM200) and all were given by oral gavage for 8 weeks. We also included a control group (C) treated with AM200 (C+AM200). The role of alpha-mangostin was assessed through its effect on blood glucose levels, HOMA-IR, blood pressure, body weight, pro-inflammatory cytokines in cardiac tissue, serum aminotransferases (ALT and AST), lipid profiles (cholesterol and triglyceride), blood urea nitrogen (BUN), uric acid, cardiac hypertrophy and fibrosis.ResultsDiabetic rats treated with alpha-mangostin in both doses for 8 weeks showed decrease in blood glucose levels, HOMA-IR, and blood pressure. Alpha-mangostin treatment also prevented HF/HG/STZ-induced changes in the activities of ALT, AST, BUN, uric acid, lipid profiles, and pro-inflammatory cytokines, which were comparable with the standard drug metformin, while alpha-mangostin did not show any significant effects on control rats (p>0.05). The cardiac hypertrophy and fibrosis were also attenuated in diabetic rats treated with alpha-mangostin in both doses.ConclusionThese data suggest that administration of alpha-mangostin can effectively attenuate diabetes-induced alteration in cardiac hypertrophy and fibrosis as well as biochemical parameters in HF/HG/STZ rats.

Rotundic Acid Protects against Metabolic Disturbance and Improves Gut Microbiota in Type 2 Diabetes Rats.

Rotundic acid (RA) is a major triterpene constituent in the barks of Ilex rotunda Thunb, which have been widely used to make herbal tea for health care in southern China. RA has a variety of bioactivities such as anti-inflammation and lipid-lowering effect. However, little is known about the effects and mechanisms of RA on metabolic disturbance in type 2 diabetes (T2D) and its effect on gut microbiota. A T2D rat model induced by high fat diet (HFD) feeding and low-dose streptozotocin (STZ) injection was employed and RA showed multipronged effects on T2D and its complications, including improving glucolipid metabolism, lowering blood pressure, protecting against cardiovascular and hepatorenal injuries, and alleviating oxidative stress and inflammation. Furthermore, 16s rRNA gene sequencing was carried out on an Illumina HiSeq 2500 platform and RA treatment could restore the gut microbial dysbiosis in T2D rats to a certain extent. RA treatment significantly enhanced the richness and diversity of gut microbiota. At the genus level, beneficial or commensal bacteria Prevotella, Ruminococcus, Leuconostoc and Streptococcus were significantly increased by RA treatment, while RA-treated rats had a lower abundance of opportunistic pathogen Klebsiella and Proteus. Spearman’s correlation analysis showed that the abundances of these bacteria were strongly correlated with various biochemical parameters, suggesting that the improvement of gut microbiota might help to prevent or attenuate T2D and its complication. In conclusion, our findings support RA as a nutraceutical agent or plant foods rich in this compound might be helpful for the alleviation of T2D and its complications through improving gut microbiota.

Pancreas protective effects of Urolithin A on type 2 diabetic mice induced by high fat and streptozotocin via regulating autophagy and AKT/mTOR signaling pathway.

Urolithin A (UroA), the main intestinal microflora metabolite of ellagic acid of berries, pomegranate,and some other traditional chinese herbals such as emblica officinalis,etc,has been reported to exhibit anti-inflammatory, anti-oxidative, anti-tumor and pro-autophagy effects. This study evaluated the anti-diabetic and pancreas-protective effects of UroA using a mice model of type 2 diabetes and preliminarily explored its effect on autophagy as well as the mechanism involved. Type 2 diabetes model was induced by high-fat diet (HFD; 60% energy as fat) and low-dose streptozotocin (85mg/kg) injection. Mice were administered with UroA (50mg/kg/d) alone or UroA-chloroquine (autophagy inhibitor) combination for 8 weeks. UroA improved symptoms of diabetic mice such as high water intake volume, high urine volume, significantly decreased fasting blood glucose (FBG), after-glucose-loading glucose, glycated hemoglobin (GHb) levels, plasma C-peptide, malondialdehyde (MDA) and interleukin-1 β level, increased reduced glutathione (GSH), interleukin-10 content, and glucose tolerance. UroA also improved pancreatic function indexes such as HOMA-β as evidenced by improved pathological and ultrastructural features of the pancreas assessed by light microscopy and transmission electron microscopy (TEM). Accordingly, UroA decreased mitochondrial swelling and myelin-like cytoplasmic inclusions. UroA significantly upregulated the protein levels of microtubule-associated protein 1 light chain 3-II (LC3II) and beclin1, downregulated sequestosome 1 (p62) accompanied by decreased expression of apoptotic protein cleaved caspase3 in pancreas of diabetic mice. In addition, it increased the phosphorylation level of protein kinase B (p-Akt) and mammalian target of rapamycin (p-mTOR). Most of these effects of UroA were reversed by treatment with autophagy inhibitor chloroquine. Our findings reveal that the pancreas protective effects of UroA against diabetes were partially mediated by its regulation of autophagy and AKT/mTOR signal pathway.

Lycium barbarum L. leaves ameliorate type 2 diabetes in rats by modulating metabolic profiles and gut microbiota composition

The leaf of Lycium barbarum L. (LLB) has been widely used as a tea, vegetable, and herb in China and Southeast Asia for centuries; this is because of the hypoglycemic effect it has, but the mechanism behind this effect is still unclear. In this study, a type 2 diabetic mellitus (T2DM) rat model, induced by a high-fat diet combined with low-dose streptozotocin (STZ) injections, was adopted. The biochemical index was determined and the histopathological and metabolomics analyses of serum and urine and 16S rDNA sequencing of the gut microbiota were performed. We evaluated the hypoglycemic effects and the mechanism of action of the water extract from LLB, which contained neochlorogenic acid, chlorogenic acid, caffeic acid, and rutin (up to 6.06%). The relationships between biochemical indexes, serum and urine metabolites, and gut microbiota were analyzed. The results showed that the LLB extract could noticeably modulate the levels of blood glucose and lipids in diabetic rats as well as repair injuries in livers, kidneys and pancreas. The changes in serum and urine metabolites caused by T2DM were reversed after the administration of LLB; these changes were found to mainly be correlated with the following pathways: nicotinate and nicotinamide metabolism, arachidonic acid metabolism, and purine metabolism. Sequencing of the 16S rDNA from fecal samples showed that the LLB extract could reverse the gut microbiota dysbiosis that T2DM had induced. Therefore, we conclude that T2DM, which altered the metabolic profiles and gut microbiota, could be alleviated effectively using the LLB extract.

Characterising an Alternative Murine Model of Diabetic Cardiomyopathy.

The increasing burden of heart failure globally can be partly attributed to the increased prevalence of diabetes, and the subsequent development of a distinct form of heart failure known as diabetic cardiomyopathy. Despite this, effective treatment options have remained elusive, due partly to the lack of an experimental model that adequately mimics human disease. In the current study, we combined three consecutive daily injections of low-dose streptozotocin with high-fat diet, in order to recapitulate the long-term complications of diabetes, with a specific focus on the diabetic heart. At 26 weeks of diabetes, several metabolic changes were observed including elevated blood glucose, glycated haemoglobin, plasma insulin and plasma C-peptide. Further analysis of organs commonly affected by diabetes revealed diabetic nephropathy, underlined by renal functional and structural abnormalities, as well as progressive liver damage. In addition, this protocol led to robust left ventricular diastolic dysfunction at 26 weeks with preserved systolic function, a key characteristic of patients with type 2 diabetes-induced cardiomyopathy. These observations corresponded with cardiac structural changes, namely an increase in myocardial fibrosis, as well as activation of several cardiac signalling pathways previously implicated in disease progression. It is hoped that development of an appropriate model will help to understand some the pathophysiological mechanisms underlying the accelerated progression of diabetic complications, leading ultimately to more efficacious treatment options.

Combined inhibition of CCR2 and ACE provides added protection against progression of diabetic nephropathy in Nos3-deficient mice.

Macrophage-mediated renal injury promotes the development of diabetic nephropathy. Blockade of chemokine (C-C motif) receptor 2 (CCR2) inhibits kidney macrophage accumulation and early glomerular damage in diabetic animals. This study tested early and late interventions with a CCR2 antagonist (CCR2A) in a model of progressive diabetic glomerulosclerosis and determined whether CCR2A provides added benefit over conventional treatment with an angiotensin-converting enzyme inhibitor (ACEi). Diabetes was induced in hypertensive endothelial nitric oxide synthase (Nos3)-deficient mice by administration of five low-dose streptozotocin (STZ) injections daily. Groups of diabetic Nos3-/- mice received a CCR2A (30 mg·kg-1·day-1 PF-04634817 in chow) as an early intervention (weeks 2-15 after STZ). The late intervention (weeks 8-15 after STZ) involved PF-04634817 alone, ACEi (captopril in water 10 mg·kg-1·day-1) alone, or combined ACEi + CCR2A. Control diabetic and nondiabetic Nos3-/- mice received normal chow and water. Early intervention with a CCR2A inhibited kidney inflammation and glomerulosclerosis, albuminuria, podocyte loss, and renal function impairment but not hypertension in diabetic Nos3-/- mice. Late intervention with a CCR2A also inhibited kidney inflammation, glomerulosclerosis, and renal dysfunction but did not affect albuminuria. ACEi alone suppressed hypertension and albuminuria and partially reduced podocyte loss and glomerulosclerosis but did not affect renal dysfunction. Compared with ACEi alone, the combined late intervention with ACEi + CCR2A provided better protection against kidney damage (inflammation, glomerulosclerosis, and renal function impairment) but not albuminuria. In conclusion, this study demonstrates that combining CCR2A and ACEi provides broader and superior renal protection than ACEi alone in a model of established diabetic glomerulosclerosis with hypertension.

Liraglutide combined with human umbilical cord mesenchymal stem cell transplantation inhibits beta-cell apoptosis via mediating the ASK1/JNK/BAX pathway in rats with type 2 diabetes.

Accumulating evidence suggests an association between beta-cell apoptosis and the ASK1/JNK/BAX pathway. The aim of this study was to investigate the effects of a combined therapy of liraglutide and human umbilical cord mesenchymal stem cells (hUC-MSCs) on the glucose metabolism and islet beta-cell apoptosis, and further explore its relationship to the ASK1/JNK/BAX pathway. Type 2 diabetes mellitus (T2DM) rat model was induced by a high-sugar and high-fat diet and intraperitoneal injection of low-dose streptozotocin (STZ) (30 mg/kg). Three days after STZ injection, diabetic rats were randomly treated with subcutaneous injection of liraglutide (200 μg/kg/12 h) for 8 weeks and or hUC-MSCs (1 × 106 /rat) at the first and fifth weeks. Diabetes-related physical and biochemical parameters, pancreatic histopathological changes, immunohistochemical staining, quantitative real-time polymerase chain reaction, and western blot were used to measure the expression of apoptosis signal-regulating kinase 1 (ASK1), Jun N-terminal kinase (JNK), Bcl-2 associated X protein (BAX), and B-cell lymphoma-2 (Bcl-2). Eight weeks after liraglutide or human umbilical cord mesenchymal stem cell administration, FPG, HbA1c , glucagon, body weight, and pancreatic ASK1, JNK, and BAX mRNA and proteins were significantly decreased, and the levels of serum C-p, INS and GLP-1, ratio of insulin positive area, and Bcl-2 expression were significantly increased in three treatment groups compared with T2DM group (P<.05). Liraglutide combined with hUC-MSCs improve glucose metabolism and inhibit islet beta-cell apoptosis in a ASK1/JNK/BAX pathway-dependent manner.

Prediction of Atorvastatin Pharmacokinetics in High-Fat Diet and Low-Dose Streptozotocin-Induced Diabetic Rats Using a Semiphysiologically Based Pharmacokinetic Model Involving Both Enzymes and Transporters.

Atorvastatin is a substrate of cytochrome P450 3a (CYP3a), organic anion-transporting polypeptides (OATPs), breast cancer-resistance protein (BCRP), and P-glycoprotein (P-gp). We aimed to develop a semiphysiologically based pharmacokinetic (semi-PBPK) model involving both enzyme and transporters for predicting the contributions of altered function and expression of CYP3a and transporters to atorvastatin transport in diabetic rats by combining high-fat diet feeding and low-dose streptozotocin injection. Atorvastatin metabolism and transport parameters comes from in situ intestinal perfusion, primary hepatocytes, and intestinal or hepatic microsomes. We estimated the expressions and functions of these proteins and their contributions. Diabetes increased the expression of hepatic CYP3a, OATP1b2, and P-gp but decreased the expression of intestinal CYP3a, OATP1a5, and P-gp. The expression and function of intestinal BCRP were significantly decreased in 10-day diabetic rats but increased in 22-day diabetic rats. Based on alterations in CYP3a and transporters by diabetes, the developed semi-PBPK model was successfully used to predict atorvastatin pharmacokinetics after oral and intravenous doses to rats. Contributions to oral atorvastatin PK were intestinal OATP1a5 < intestinal P-gp < intestinal CYP3a < hepatic CYP3a < hepatic OATP1b2 < intestinal BRCP. Contributions of decreased expression and function of intestinal CYP3a and P-gp by diabetes to oral atorvastatin plasma exposure were almost attenuated by increased expression and function of hepatic CYP3a and OATP1b2. Opposite alterations in oral plasma atorvastatin exposure in 10- and 22-day diabetic rats may be explained by altered intestinal BCRP. In conclusion, the altered atorvastatin pharmacokinetics by diabetes was the synergistic effects of altered intestinal or hepatic CYP3a and transporters and could be predicted using the developed semi-PBPK.

SAT-164 Mice with established diabetes have enhanced susceptibility to renal ischaemia/reperfusion injury: role of the JNK signalling pathway

Renal ischaemia/reperfusion (I/R) injury is a common cause of acute kidney injury. However, the clinical situation is often complex with patients having co-morbidities such as diabetes that make them more susceptible to I/R-induced acute kidney injury. To address this, we sought to develop a model of renal I/R injury in mice with established diabetes. Activation of the c-Jun amino terminal kinase (JNK) is known to play a role in various types of acute kidney injury; however, whether this is important in diabetic I/R injury is unknown. The aims of this study were to: (i) characterize a model of renal I/R injury in diabetic mice, and; (ii) determine if treatment with the JNK inhibitor, CC-930, can prevent the development of I/R-induced acute kidney injury in diabetic mice. Groups of 8 to 10 mice were made diabetic by 5 daily injections of low dose streptozotocin (STZ). Diabetes was monitored weekly by fasting blood glucose levels. After 8 weeks, mice underwent 13min of bilateral renal ischaemia and were killed 24hr after reperfusion (i.p. saline was provided to minimize fluid loss). Groups of mice received either 150mg/kg/BID CC-930 or vehicle alone by oral gavage starting 1hr before surgery. The same 13min ischaemic insult was performed in age-matched non-diabetic mice as a control. Diabetic mice had normal renal function at 8 weeks after STZ injections (14.3±0.8 vs 12.5±1.9umol/L serum creatinine (sCr) in non-diabetic; P=NS). Bilateral ischaemia of 13min caused more severe renal dysfunction in diabetic compared to non-diabetic mice (82.7±25.4 vs 31.6±11.9umol/L sCr, respectively; P<0.001). The percentage of tubules showing damage in the inner cortex and outer medulla was also greater in diabetic vs non-diabetic I/R injury (61±17% vs 26±12% damaged tubules, respectively; P<0.001). Activation of JNK signalling, shown by c-Jun phosphorylation, was substantially increased in diabetic versus non-diabetic I/R kidney. Treatment with CC-930 inhibited JNK signalling and substantially reduced the severity of acute kidney injury in the diabetic I/R model (28.6±5.7umol/L sCr and 16±7% damaged tubules; both P<0.001 vs vehicle treated diabetic I/R). Mice with established diabetes, but without overt kidney disease, have an increased susceptibility to I/R-induced acute kidney injury with enhanced JNK signalling. Prophylactic treatment with a JNK inhibitor gave substantial protection against I/R-induced renal injury in diabetic mice.

167-OR: Activation of Myocardial Mitochondria Akt1 Improved Diabetic Cardiomyopathy and Body Composition—The Heart as a Metabolic Organ

Insulin acutely stimulates Akt1 translocation into cardiac mitochondria, which is blunted in T2DM due to insulin resistance. To study the role of mitochondrial Akt (mito-Akt) in diabetic cardiomyopathy and its implication on whole body metabolism, we generated two transgenic mice lines with heart-specific Cre-lox, using inducible mitochondria-targeting dominant negative Akt (CAMDAKT) or constitutively active Akt (CAMCAKT). CAMDAKT mice developed cardiomyopathy and heart failure after Tamoxifen (T) induction when compared to corn oil (CO) injected CAMDAKT mice. To study whether activation of myocardial mito-Akt can reverse diabetic cardiomyopathy, two models of diabetic cardiomyopathy resembling different phases of T2DM were used in this study. First, after 5-months high fat/fructose diet (HFF), mice developed LV dysfunction, obesity, glucose intolerance, and hyperinsulinemia. In this model, T-CAMCAKT mice restored LV function and averted cardiomyopathy. A second metabolic model was induced with a 12-weeks HFF diet and low-dose streptozotocin injections, which led to overweight, hyperglycemia, and reduced insulin secretion. CO mice showed higher heart failure markers (ANF, BNP, MYH7) and increased expression of cardiac PDK4, CPT1, CPT2 and CD36. In the T-CAMCAKT mice, cardiomyopathy was reversed. Thus, activation of mito-Akt reversed diabetic cardiomyopathy. While T-CAMCAKT showed similar improvement of cardiomyopathy in these two metabolic models, body composition was different. In the first HFF model, mito-Akt activation did not alter body composition or glucose homeostasis, but fatty liver was improved. In the second metabolic model with reduced insulin secretion, T-CAMCAKT mice had better OGTT, lower fat mass (16.6% vs. 26.5%, p&amp;lt;0.001) and higher lean mass (77.1% vs. 68.1%, p&amp;lt;0.001). Summary: myocardial mito-Akt locally modulated cardiac metabolism and LV function, and remotely modulated whole body metabolism. Disclosure Y. Chen: None. A. Ta: None. H. Lee: None. H.Y. Lin: None. Y. Chen: None. P.H. Wang: None.

The alterations of bile acids in rats with high-fat diet/streptozotocin-induced type 2 diabetes and their negative effects on glucose metabolism

PurposeBile acids (BAs) as a kind of endogenous and signaling molecules altered under the circumstance of T2DM, which could impact on the relevant pathways to further affect the glucose metabolism and insulin secretion and might be associated with the T2DM development and restoration. However, the potential mechanisms still need more various and multifaceted studies. Here, we explored the alterations of BAs features and their mechanisms, and discussed the potential effects of the altered BAs on the glucose metabolic disorder via the relevant signaling pathways. Main methodsThe high-fat diet (HFD) feeding combining with injection of low-dose streptozotocin (STZ) was employed for inducing the T2DM rat model. Based on that, we investigated the alterations of the concentrations and compositions of BAs and their mechanisms, and explored the effects of the altered BAs on the glucose metabolic disorder via farnesoid X receptor (Fxr) and G protein-coupled bile acid receptor (Tgr5)-mediated pathways. Key findingsIn rats with T2DM, the BAs in rats with T2DM exhibited characteristic alterations, especially the increased ratio of 12α-OH to non-12α-OH BAs in serum, which could be ascribed to the up-regulated Cyp8b1 mRNA expression ratio in the liver. Moreover, Additionally, the altered BAs had negative effects on glucose metabolic disorder via inhibiting the Trg5/Fxr-mediated pathways in colon, liver and pancreas in rats with T2DM. SignificanceBAs in rats with T2DM exhibited the characteristic alterations, which could provide a cue for searching biomarkers of the T2DM diagnosis, and the altered BAs might aggravate the glucose metabolic disorder.

Effect of Irbesartan on Oxidative Stress and Serum Inflammatory Factors in Renal Tissues of Type 2 Diabetic Rats.

To determine the effect of irbesartan on the activity of oxidative stress parameters of glutathione (GSH), superoxide enzyme (SOD) and malondialdehyde (MDA), and concentration of serum inflammatory factors of macrophage chemokine-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor alpha (TNF-∝) in the renal tissue of type 2 diabetic rats. An experimental study. The First People's Hospital of Ningyang County, Shandong Province, China, from April 2017 to March 2018. Thirty healthy male Sprague Dawley rats were randomly divided into a normal control group, a diabetic model group, and an irbesartan treatment group, 10 in each group. Rat models of type 2 diabetes were prepared by highsugar high-fat diet with low-dose streptozotocin injection. Changes in blood glucose and lipids, serum GSH, SOD, MDA, MCP-1, ICAM-1, and TNF-∝ levels were determined. Levels of FBG, TC, TG and LDL, activity of GSH, SOD and MDA, and levels of serum MCP-1, ICAM-1 and TNF-∝ among three groups were statistically significant (all p < 0.001). Compared with the diabetic model group, FBG, TC, TG and LDL levels, MDA activity, MCP-1, ICAM-1 and TNF-∝ levels all decreased in rats of the irbesartan treatment group (all p <0.001), and both GSH and SOD activity increased (both p<0.001). Irbesartan can improve blood glucose and lipid levels in type 2 diabetic rats, and reduce renal damage by improving oxidative stress and inhibiting the release of inflammatory cytokines.

Role of MicroRNA-34a in Anti-Apoptotic Effects of Granulocyte-Colony Stimulating Factor in Diabetic Cardiomyopathy.

BackgroundRecent studies have shown that microRNAs (miRNAs) are involved in the process of cardiomyocyte apoptosis. We have previously reported that granulocyte-colony stimulating factor (G-CSF) ameliorated diastolic dysfunction and attenuated cardiomyocyte apoptosis in a rat model of diabetic cardiomyopathy. In this study, we hypothesized a regulatory role of cardiac miRNAs in the mechanism of the anti-apoptotic effect of G-CSF in a diabetic cardiomyopathy rat model.MethodsRats were given a high-fat diet and low-dose streptozotocin injection and then randomly allocated to receive treatment with either G-CSF or saline. H9c2 rat cardiomyocytes were cultured under a high glucose (HG) condition to induce diabetic cardiomyopathy in vitro. We examined the extent of apoptosis, miRNA expression, and miRNA target genes in the myocardium and H9c2 cells.ResultsG-CSF treatment significantly decreased apoptosis and reduced miR-34a expression in diabetic myocardium and H9c2 cells under the HG condition. G-CSF treatment also significantly increased B-cell lymphoma 2 (Bcl-2) protein expression as a target for miR-34a. In addition, transfection with an miR-34a mimic significantly increased apoptosis and decreased Bcl-2 luciferase activity in H9c2 cells.ConclusionOur results indicate that G-CSF might have an anti-apoptotic effect through down-regulation of miR-34a in a diabetic cardiomyopathy rat model.

A Simple and Effective Non-Human Primate Diabetic Model Combining Sub-Total Pancreatectomy and Low-Dose Streptozotocin Injection

BACKGROUND. Current non-human primate diabetic models, namely those induced by total pancreatectomy or streptozotocin (STZ) injection, suffer from several disadvantages, including a long surgical procedure, the need for continual digestive enzyme replacement, and a delayed oral intake after total pancreatectomy and severe hypoglycemia and hepatic/renal toxicity with high-dose STZ injection. AIM. To construct and optimize a non-human primate diabetic model that avoids the disadvantages of current approaches and compare it to the STZ model. METHODS. Diabetes was induced in male Cynomolgus monkeys (n=4) by performing subtotal pancreatectomy followed by low-dose STZ injection (30 [n=1], 45 [n=2] and 60 [n=1] mg/kg). This model was compared to STZ injection only (60 [n=1] and 100 [n=9] mg/kg) regarding the development of diabetes (serum C-peptide and pancreatic anti-insulin staining), the liver (glutamine-ornithine-transaminase and glutamine-pyruvate-trasnaminase levels) and kidney functions (BUN and creatinine levels), and the general condition (weight loss, food intake, and activity). RESULTS. The serum C-peptide levels after glucose challenge in the combined model were comparable (0 ng/mL) to those with high-dose STZ injection (100 mg/kg). The absence of pancreatic insulin staining was demonstrated when 60 mg/kg STZ was used after subtotal pancreatectomy and with 100 mg/kg STZ injection only. The combined model did not suffer from hypoglycemic episodes and showed better activity and oral intake than the STZ-only model. Liver enzyme levels were markedly lower in the new model, while BUN and creatinine levels were higher than with STZ alone. CONCLUSIONS. Diabetes was successfully induced using the combined technique without the need for a lengthy operation or continual digestive enzyme replacement. In addition, the reduction in the pancreatic volume allowed for lower STZ utilization which led to less hepatic toxicity and the absence of hypoglycemic episodes. However, adequate fluid administration may be required to guard against renal STZ toxicity.

Tangduqing Granules Attenuate Insulin Resistance and Abnormal Lipid Metabolism through the Coordinated Regulation of PPARγ and DGAT2 in Type 2 Diabetic Rats.

Insulin resistance (IR) is a vital hallmark of type 2 diabetes mellitus, which is characterized by an impaired ability of insulin to promote glucose uptake and utilization. Lipid deposition is closely associated with impaired insulin sensitivity. PPARγ plays an important role in glucose homeostasis, adipocyte differentiation, and insulin sensitivity. Likewise, DGAT2 also exerts a crucial role in integrating carbohydrate and lipid metabolism in the liver. The present study is aimed at evaluating a Chinese medicinal formula, Tangduqing granules (TDQ), with multifaceted actions against lipid and glucose metabolism disorder and IR of type 2 diabetes. An animal model of type 2 diabetes was developed by high-fat diet feeding plus low-dose streptozotocin injection. After oral administration of TDQ for 5 weeks, the effects on glucose and lipid metabolism and the underlying mechanism were evaluated by biochemical, histological, RT-PCR, and western blotting methods. The results showed that TDQ decreased fasting blood glucose, ameliorated glucose tolerance, and improved IR. Besides, TDQ regulated hyperlipidemia symptoms, decreased serum lipid levels and liver TG, and reduced hepatic steatosis in a type 2 diabetic rat model. Furthermore, TDQ reversed diabetes-induced decrease in the mRNA and protein expression of PPARγ and elevation in the mRNA and protein levels of DGAT2 in the liver. In addition, we showed that interference of TDQ ameliorated palmitate-induced glucose and lipid metabolic abnormalities in HepG2 cells. TDQ are, therefore, a potential Chinese medicinal formula that relieves IR and lipid metabolism disorder might be through promotion of PPARγ and decrease of DGAT2 expression.

The Effect of Puguntano Leaf Extract (Curanga Fel - Terrae Merr.) On P38 Mapk Levels and Glut-4 Expression in Type 2 Diabetic Rat Muscle.

BACKGROUND:Puguntano (Curanga feel-terrae Merr.) contains flavonoids, saponins, tannins, and steroids/ terpenoids which improved post-receptor insulin signalling in rats model of type 2 diabetes mellitus (T2DM).AIM:This study aimed to determine the effect of puguntano leaf extract on p38 mitogen-activated protein kinase (MAPK) levels and glucose transporter-4 (GLUT-4) expression in diabetic rats muscle.METHODS:Forty-eight male Wistar rats had T2DM induced using a combination of feeding a high-fat diet for 5 weeks and multiple intraperitoneal injections of low-dose streptozotocin (30 mg/kg). The diabetic rats were randomly divided into control and treatment groups, and 200 mg/kg/day puguntano extract was administered orally for 10 days to treatment group. Subsequently, p38 MAPK levels were measured by Sandwich Elisa and plasma membrane GLUT-4 expression was evaluated by Immunohistochemistry in their gastrocnemius muscles.RESULTS:There were significantly higher p38 MAPK levels and GLUT-4 expression in the treatment group than in the control group.CONCLUSION:These data suggest that a puguntano leaf extract can improve post-receptor insulin signalling by enhancing p38 MAPK levels and GLUT-4 expression in a rat model of T2DM.

Inhibition of Ephrin-B2 in brain pericytes decreases cerebral pathological neovascularization in diabetic rats.

We have previously shown that diabetes causes dysfunctional cerebral neovascularization that increases the risk for cerebrovascular disorders such as stroke and cognitive impairment. Pericytes (PCs) play a pivotal role in the angiogenic process through their interaction with the endothelial cells (EC). Yet, the role of PCs in dysfunctional cerebral neovascularization in diabetes is unclear. In the present study, we tested the hypothesis that the increased proangiogenic Ephrin-B2 signaling in PCs contributes to the dysfunctional cerebral neovascularization in diabetes. Type-II diabetes was induced by a combination of high fat diet and low dose streptozotocin injection in male Wistar rats. Selective in vivo Ephrin-B2 silencing in brain PCs was achieved using the stereotactic injection of adeno-associated virus (AAV) with NG2-promoter that expresses Ephrin-B2 shRNA. Neovascularization was assessed using vascular fluorescent dye stain. Novel object recognition (NOR) test was used to determine cognitive functions. Human brain microvascular pericytes HBMVPCs were grown in high glucose 25 mM and palmitate 200 uM (HG/Pal) to mimic diabetic conditions. Scratch migration and tube formation assays were conducted to evaluate PC/EC interaction and angiogenic functions in PC/EC co-culture. Diabetes increased the expression of Ephrin-B2 in the cerebrovasculature and pericytes. Concomitant increases in cerebral neovascularization parameters including vascular density, tortuosity and branching density in diabetic rats were accompanied by deterioration of cognitive function. Inhibition of Ephrin-B2 expression in PCs significantly restored cerebral vascularization and improved cognitive functions. HG/Pal increased PC/EC angiogenic properties in co-culture. Silencing Ephrin-B2 in PCs significantly reduced PC migration and PC/EC co-culture angiogenic properties. This study emphasizes the significant contribution of PCs to the pathological neovascularization in diabetes. Our findings introduce Ephrin-B2 signaling as a promising therapeutic target to improve cerebrovascular integrity in diabetes.