Hemin mitigates contrast-induced nephropathy by inhibiting ferroptosis via HO-1/Nrf2/GPX4 pathway.

Contrast-induced nephropathy (CIN) is a common complication with adverse outcome after iodinated-contrast injection, yet still lacking effective medication. Heme oxygenase-1 (HO-1) has been reported to play an important role against renal injuries. Hemin, a HO-1 inducer and anti-porphyria medicine, may have a promising effect against CIN. In this study, we aim to investigate the effect of hemin on CIN model and the underlying molecular mechanisms in human proximal tubule epithelial cells (HK-2). To mimic a common condition in percutaneous coronary intervention (PCI) patients, CIN was induced by intravenous iopromide in high-fat fed diabetic rats. We found hemin, given right before iopromide, mitigated CIN with enhanced antioxidative capacity and reduced oxidative stress. HK-2 cells insulted by iopromide demonstrated decreased cell vitality and rising reactive oxygen species (ROS), which could also be inhibited by hemin. The effects of hemin involved a key molecule in ferroptosis, glutathione peroxidase (GPX4), whose down-expression by small interfering RNA (siRNA) reversed the effect of hemin on HK-2 cells. Furthermore, hemin's induction of GPX4 involved HO-1 and nuclear factor erythroid 2-related factor 2 (Nrf2). Either HO-1 or Nrf2 inhibitor prevented hemin's effect on GPX4 to a comparable extent, and over-expression of Nrf2 increased GPX4 expression. Moreover, intervention of ferroptosis inhibitor liproxstatin-1 also alleviated CIN in vivo. Therefore, we showed hemin mitigated CIN, inhibiting oxidative stress and ferroptosis, by upregulation of GPX4 via activation of HO-1/Nrf2. Hemin, as a clinical medicine, has a translational significance in treating CIN, and anti-ferroptosis is a potential therapeutic strategy for CIN.

Intestinal Region-Specific and Layer-Dependent Induction of TNFα in Rats with Streptozotocin-Induced Diabetes and after Insulin Replacement.

Tumour necrosis factor alpha (TNFα) is essential in neuroinflammatory modulation. Therefore, the goal of this study is to reveal the effects of chronic hyperglycaemia and insulin treatment on TNFα expression in different gut segments and intestinal wall layers. TNFα expression was mapped by fluorescent immunohistochemistry and quantitative immunogold electron microscopy in myenteric ganglia of duodenum, ileum and colon. Tissue TNFα levels were measured by enzyme-linked immunosorbent assays in muscle/myenteric plexus-containing (MUSCLE-MP) and mucosa/submucosa/submucous plexus-containing (MUC-SUBMUC-SP) homogenates. Increasing density of TNFα-labelling gold particles is observed in myenteric ganglia from proximal to distal segments and TNFα tissue levels are much more elevated in MUSCLE-MP homogenates than in MUC-SUBMUC-SP samples in healthy controls. In the diabetics, the number of TNFα gold labels is significantly increased in the duodenum, decreased in the colon and remained unchanged in the ileal ganglia, while insulin does not prevent these diabetes-related TNFα changes. TNFα tissue concentration is also increased in MUSCLE-MP homogenates of diabetic duodenum, while decreased in MUC-SUBMUC-SP samples of diabetic ileum and colon. These findings support that type 1 diabetes has region-specific and intestinal layer-dependent effects on TNFα expression, contributing to the regional damage of myenteric neurons and their intestinal milieu.

A novel neurotensin/xenin fusion peptide enhances ß-cell function and exhibits antidiabetic efficacy in high-fat fed mice.

Neurotensin and xenin possess antidiabetic potential, mediated in part through augmentation of incretin hormone, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), action. In the present study, fragment peptides of neurotensin and xenin, acetyl-neurotensin and xenin-8-Gln, were fused together to create Ac-NT/XN-8-Gln. Following assessment of enzymatic stability, effects of Ac-NT/XN-8-Gln on in vitro ß-cell function were studied. Subchronic antidiabetic efficacy of Ac-NT/XN-8-Gln alone, and in combination with the clinically approved GLP-1 receptor agonist exendin-4, was assessed in high-fat fed (HFF) mice. Ac-NT/XN-8-Gln was highly resistant to plasma enzyme degradation and induced dose-dependent insulin-releasing actions (P<0.05 to P<0.01) in BRIN-BD11 ß-cells and isolated mouse islets. Ac-NT/XN-8-Gln augmented (P<0.001) the insulinotropic actions of GIP, while possessing independent ß-cell proliferative (P<0.001) and anti-apoptotic (P<0.01) actions. Twice daily treatment of HFF mice with Ac-NT/XN-8-Gln for 32 days improved glycaemic control and circulating insulin, with benefits significantly enhanced by combined exendin-4 treatment. This was reflected by reduced body fat mass (P<0.001), improved circulating lipid profile (P<0.01) and reduced HbA1c concentrations (P<0.01) in the combined treatment group. Following an oral glucose challenge, glucose levels were markedly decreased (P<0.05) only in combination treatment group and superior to exendin-4 alone, with similar observations made in response to glucose plus GIP injection. The combined treatment group also presented with improved insulin sensitivity, decreased pancreatic insulin content as well as increased islet and ß-cell areas. These data reveal that Ac-NT/XN-8-Gln is a biologically active neurotensin/xenin fusion peptide that displays prominent antidiabetic efficacy when administered together with exendin-4.

Hormonal regulation of glycine decarboxylase and its relationship to oxidative stress.

In both humans and rodent models, circulating glycine levels are significantly reduced in obesity, glucose intolerance, type II diabetes, and non-alcoholic fatty liver disease. The glycine cleavage system and its rate-limiting enzyme, glycine decarboxylase (GLDC), is a major determinant of plasma glycine levels. The goals of this study were to determine if the increased expression of GLDC contributes to the reduced plasma glycine levels seen in disease states, to characterize the hormonal regulation of GLDC gene expression, and to determine if altered GLDC expression has physiological effects that might affect the development of diabetes. The findings presented here show that hepatic GLDC gene expression is elevated in mouse models of obesity and diabetes, as well as by fasting. We demonstrated that GLDC gene expression is strongly regulated by the metabolic hormones glucagon and insulin, and we identified the signaling pathways involved in this regulation. Finally, we found that GLDC expression is linked to glutathione levels, with increased expression associated with elevated levels of glutathione and reduced expression associated with a suppression of glutathione and increased cellular ROS levels. These findings suggest that the hormonal regulation of GLDC contributes not only to the changes in circulating glycine levels seen in metabolic disease, but also affects glutathione production, possibly as a defense against metabolic disease-associated oxidative stress.

The sodium-glucose cotransporter-2 inhibitor Tofogliflozin prevents the progression of nonalcoholic steatohepatitis-associated liver tumors in a novel murine model.

BACKGROUND: Diabetes and obesity contribute to the pathogenesis of nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). However, how diabetes and obesity accelerate liver tumorigenesis remains to be fully understood. Moreover, to verify the therapeutic potential of anti-diabetic drugs, there exists a strong need for appropriate animal models that recapitulate human pathophysiology of NASH and HCC. METHODS: We established a novel murine model of NASH-associated liver tumors using genetically obese melanocortin 4 receptor-deficient mice fed on Western diet in combination with a chemical procarcinogen, and verified the validity of our model in evaluating drug efficacy. FINDINGS: Our model developed multiple liver tumors together with obesity, diabetes, and NASH within a relatively short period (approximately 3 months). In this model, sodium glucose cotransporter 2 inhibitor Tofogliflozin prevented the development of NASH-like liver phenotypes and the progression of liver tumors. Tofogliflozin attenuated p21 expression of hepatocytes in non-tumorous lesions in the liver. INTERPRETATION: Tofogliflozin treatment attenuates cellular senescence of hepatocytes under obese and diabetic conditions. This study provides a unique animal model of NASH-associated liver tumors, which is applicable for assessing drug efficacy to prevent or treat NASH-associated HCC.

From virus to diabetes therapy: Characterization of a specific insulin-degrading enzyme inhibitor for diabetes treatment.

Inhibition of insulin-degrading enzyme (IDE) is a possible target for treating diabetes. However, it has not yet evolved into a medical intervention, mainly because most developed inhibitors target the zinc in IDE's catalytic site, potentially causing toxicity to other essential metalloproteases. Since IDE is a cellular receptor for the varicella-zoster virus (VZV), we constructed a VZV-based inhibitor. We computationally characterized its interaction site with IDE showing that the peptide specifically binds inside IDE's central cavity, however, not in close proximity to the zinc ion. We confirmed the peptide's effective inhibition on IDE activity in vitro and showed its efficacy in ameliorating insulin-related defects in types 1 and 2 diabetes mouse models. In addition, we suggest that inhibition of IDE may ameliorate the pro-inflammatory profile of CD4+ T-cells toward insulin. Together, we propose a potential role of a designed VZV-derived peptide to serve as a selectively-targeted and as an efficient diabetes therapy.

Antidiabetic and Renoprotective Effects of Coffea arabica Pulp Aqueous Extract through Preserving Organic Cation Transport System Mediated Oxidative Stress Pathway in Experimental Type 2 Diabetic Rats.

Coffea arabica pulp (CP) is a by-product of coffee processing. CP contains polyphenols that have exhibited beneficial effects, including antioxidant and lipid-lowering effects, as well as enhanced insulin sensitivity, in in vitro and in vivo models. How polyphenols, as found in CP aqueous extract (CPE), affect type 2 diabetes (T2D) has not been investigated. Thus, the present study examined the potential antidiabetic, antioxidant, and renoprotective effects of CPE-rich polyphenols, using an experimental model of T2D in rats induced by a high-fat diet and a single low dose of streptozotocin. The T2D rats received either 1000 mg/kg body weight (BW) of CPE, 30 mg/kg BW of metformin (Met), or a combination treatment (CPE + Met) for 3 months. Plasma parameters, kidney morphology and function, and renal organic transport were determined. Significant hyperglycemia, hypertriglyceridemia, insulin resistance, increased renal lipid content and lipid peroxidation, and morphological kidney changes related to T2D were restored by both CPE and CPE + Met treatments. Additionally, the renal uptake of organic cation, 3H-1-methyl-4-phenylpyridinium (MPP+), was reduced in T2D, while transport was restored by CPE and CPE + Met, through an up-regulation of antioxidant genes and protein kinase Cα deactivation. Thus, CPE has antidiabetic and antioxidant effects that potentially ameliorate kidney function in T2D by preserving renal organic cation transport through an oxidative stress pathway.

Vitexin, a fenugreek glycoside, ameliorated obesity-induced diabetic nephropathy via modulation of NF-κB/IkBα and AMPK/ACC pathways in mice.

Obesity is one of the most critical risk factors for diabetes mellitus and plays a significant role in diabetic nephropathy (DN). The present investigation aimed to evaluate the possible mechanism of action of vitexin on obesity-induced DN in a high-fat diet (HFD)-fed experimental C57BL/6 mice model. Obesity was induced in male C57BL/6 mice by chronic administration of HFD, and mice were concomitantly treated with vitexin (15, 30, and 60 mg/kg, p.o.). HFD-induced increased renal oxido-nitrosative stress and proinflammatory cytokine levels were significantly inhibited by vitexin. The Western blot analysis suggested that alteration in renal NF-κB, IκBα, nephrin, AMPK, and ACC phosphorylation levels was effectively restored by vitexin treatment. Histological aberration induced in renal tissue after chronic administration of HFD was also reduced by vitexin. In conclusion, vitexin suppressed the progression of obesity-induced DN via modulation of NF-κB/IkBα and AMPK/ACC pathways in an experimental model of HFD-induced DN in C57BL/6J mice.

Combined therapy of mesenchymal stem cells with a GLP-1 receptor agonist, liraglutide, on an inflammatory-mediated diabetic non-human primate model.

AIMS: Immunomodulation concurrent with the promotion of ß-cell function is a strategy used to develop innovative therapies for type 1 diabetes (T1D). Here, we assessed the therapeutic potential of co-administration of human clonal mesenchymal stem (stromal) cells (hBM-cMSCs) and liraglutide as a glucagon-like peptide-1 agonist in a non-human primate model with streptozotocin (STZ)-induced diabetes. MAIN METHODS: Diabetes was induced through intravenous (i.v.) multiple low-dose (MLD) infusions of STZ at a dose of 30 mg/kg body weight (b.w.) for five consecutive days, followed by two booster injections of 35 mg/kg on days 12 and 19. After 90 days, the diabetic animals were randomly allocated to two groups: The combination therapy group (n = 4) received injections of 1.5 × 106 hBM-cMSCs/kg b.w. through celiac artery by angiography on days 91 and 105 and daily subcutaneous injections of liraglutide (up to 1.8 mg/day) until day 160 while vehicle group received phosphate-buffered saline. The monkeys were assessed for functional, immunological, and histological analysis. KEY FINDINGS: The combined treatment group had continued reduction in FBG levels up to day 160, which was accompanied by increased b.w., C-peptide, and ß-cell function, and decreased HbA1c and fructosamine levels compared to vehicle group. The combined treatment increased Tregs, IL-4, IL-10, and TGF-ß1 and decreased IL-6 and IL-1ß. Stereological analysis of the pancreatic tissue exhibited more total volume of insulin-secreting islets in the combined treatment group compared to vehicle group. SIGNIFICANCE: Our findings demonstrated this combined treatment impaired the clinical symptoms of diabetes in this animal model through immunomodulation and ß-cell preservation.

Novel XTENylated AWRK6 analog with hypoglycemic activity, and anti-HSV-2 potential in combination with double shRNA.

AIMS: To design and evaluate a novel AWRK6 peptide-based long-acting GLP-1 receptor agonist (GLP-1RA) conjugated a recombinant polyethylene glycol mimetic (XTEN protein) with significant therapeutic potential on type 2 diabetes mellitus (T2DM) alone as well as Herpes simplex virus type 2 (HSV-2) infection in combination with double shRNA. MAIN METHODS: First, four AWRK6 analogs (termed XA-1 to XA-4) were designed and produced by solid phase synthesis strategy. Further surface plasmon resonance (SPR) measurement and in vitro cAMP accumulation assay were performed to detect the GLP-1R binding affinities and GLP-1R activation, respectively. The in vivo efficacy evaluation including pharmacokinetic test, oral glucose tolerance test (OGTT), hypoglycemic duration test and chronic pharmacodynamics study in rodent animals were all carefully performed. KEY FINDINGS: Four XA peptides were synthesized with purity >99%. High binding affinity as well as activation potency of XA-4 for GLP-1R were demonstrated by SPR and cell-based luciferase reporter assay, respectively. Additionally, XA-4 exhibited the long-lasting antidiabetic effects in the multiple OGTTs, hypoglycemic duration test and chronic study in mice. Furthermore, combined treatment of XA-4 and double shRNA (D-shRNA) achieved potent antiviral effects in HSV-2 infected HEK293 cells. SIGNIFICANCE: XA-4 exhibited promising pharmaceutical potential to be a therapeutic drug for treating T2D, and also held potential to against the HSV-2 infection, which is really an accidental discovery. The strategy of recombinant XTENylation can also be applied to other peptides or small molecules for the development of long-acting therapeutic drugs.

Protein Isolates from Raw and Cooked Foxtail Millet Attenuate Development of Type 2 Diabetes in Streptozotocin-Induced Diabetic Mice.

SCOPE: Millet protein has received much attention due to its beneficial role in alleviating metabolic disease symptoms. This study aims to investigate the role and molecular mechanism of foxtail millet protein isolates, including protein isolates from raw and cooked foxtail millet in alleviating diabetes, including gut microbiota and intracellular signal pathways. METHODS AND RESULTS: Protein isolates from raw and cooked foxtail millet are orally administered to streptozotocin (STZ)-induced diabetic mice for 5 weeks before hypoglycemic effect evaluation. The results show that foxtail millet protein isolates improve glucose intolerance and insulin resistance in diabetic mice. However, only the protein isolate from cooked foxtail millet reverse the weight loss trend and alleviate lipid disorders in diabetic mice. Besides, 16S rRNA sequencing show that both raw and cooked foxtail millet protein isolates altered diabetes-induced gut dysbiosis. In addition, western blotting analysis indicated that the protein isolate from cooked foxtail millet increases the expression levels of glucagon-like peptide-1 receptor (GLP-1R), phosphoinositide 3-kinase (PI3K), and phosphoinositide-protein kinase B (p-AKT)/AKT while the protein isolate from raw foxtail millet downregulates stearoyl-coenzyme A desaturase 1 (SCD1) level. CONCLUSION: Both raw and cooked foxtail millet protein isolates can exert hypoglycemic effects in diabetic mice through rewiring glucose homeostasis, mitigating diabetes-induced gut dysbiosis, and affecting the GLP-1R/PI3K/AKT pathway.

Effect of curcuma on zinc, lipid profile and antioxidants levels in blood and tissue of streptozotocin-induced diabetic rats fed zinc deficiency diet.

Due to the importance of zinc as an antioxidant and its crucial role in insulin synthesis, its deficiency may affect adversely diabetic state. So, this study aimed to modulate these effects using Curcuma longa as natural antioxidant. Rats were divided into four groups: two groups fed a zinc sufficient diet one non-diabetic and the other diabetic, while the others two groups diabetic rats fed a zinc-deficient diet, one non-treated group and the other treated with curcuma 1% diet. After four weeks of dietary manipulation, fasting animals were scarified. Zinc deficiency decreased body weight, insulin, zinc tissues, alkaline phosphatase, reduced glutathione, glutathione peroxidase, superoxide dismutase and catalase. Conversely glucose, lipids profile, transaminases and malondialdehyde were increased. However, the above-mentioned parameters were significantly improved following curcuma supplementation. So it seems that curcuma is a potent factor for reducing the oxidative severity of zinc deficiency in experimental diabetes through its antioxidants actions.

Modulatory effect of isopulegol on hepatic key enzymes of glucose metabolism in high-fat diet/streptozotocin-induced diabetic rats.

To investigate the antidiabetic effect of isopulegol in high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic rats. Animals were made diabetic by feeding HFD for 4 weeks followed by single intraperitoneal injection of STZ (35 mg/kg b.w.; 0.1 M citrate buffer; pH 4.0). Plasma insulin, haemoglobin and glycogen content were decreased while increased glucose and glycated haemoglobin were observed in diabetic rats. An increase in glucose-6-phosphatase, fructose-1,6-bisphosphatase, phosphoenol pyruvate carboxykinase with a decrease in hexokinase, glucose-6-phosphate dehydrogenase and glycogen synthase activities was observed in diabetic rats. The expression of cyclic response element binding protein (CREB) was increased in the hepatic tissue of diabetic rats. Isopulegol dose dependently (50, 100 and 200 mg/kg b.w.) improved insulin secretion, glucose tolerance and decreased glucose levels in diabetic-treated rats. At the effective dose of 100 mg/kg b.w., isopulegol restored the activities of metabolic enzymes and down-regulated CREB expression. Thus, isopulegol restored glucose homeostasis through its insulinotrophic property.

L-carnitine improves metabolic disorders and regulates apelin and apelin receptor genes expression in adipose tissue in diabetic rats.

Apelin is a new adipocytokine that acts as an endogenous hormone in various tissues through its receptor (APJ). This study aimed to investigate the effects of oral administration of L-carnitine (LC) on the expression of Apelin and APJ in adipose tissue of experimentally induced insulin-resistant and type 2 diabetic rats. In this experimental study, 60 male rats fed with high fat/high carbohydrate (HF/HC) diet. After 50 mg/kg intraperitoneally injection of streptozotocin (STZ) and confirmation of diabetes (FBS higher than 126 mg/dl), the animals were daily treated with 300 mg/kg LC for 28 days. At days 7, 14, and 28 of posttreatment, the expression of apelin and APJ in adipose tissue were determined using qPCR in diabetic, diabetic + LC treated, control, and control + LC treated groups. Apelin, insulin, TNF-α, and IL1-ß were measured by the ELISA method. Results demonstrated that the rats fed with the HF/HC diet for 5 weeks were hyperinsulinemic and normoglycemic, while after STZ injection, they showed hyperinsulinemia and hyperglycemia with higher levels of HOMA-IR. Apelin serum level, APJ and apelin gene expression in adipose tissue increased significantly with the development of diabetes compared to the control group. Treatment with LC for 14 days caused a reduction in apelin and APJ expressions in adipose tissue of diabetic rats. TNF-α and IL1-ß levels were reduced in diabetic rats 14 days after their treatment with LC. The study results show that L-carnitine could act as a new regulator in apelin gene expression in adipose tissue, improving the metabolic disorders in diabetic patients.

Paeoniflorin accelerates foot wound healing in diabetic rats though activating the Nrf2 pathway.

As one of the most frequent diabetic complications, diabetic foot ulcer (DFU) can cause limb ischemia or even amputation. Paeoniflorin (PF) has been reported to possess many kinds of biological functions, such as antioxidant and anti-inflammatory effects. However, the role of PF in DFU remains unknown. In this study, streptozotocin (STZ)-induced diabetic rat models and high glucose (HG)-treated Human immortalized keratinocytes (HaCaT) cells were established. Histological analysis, immunohistochemistry, Electrophoretic mobility shift assay, MTT assay, TUNEL assay, oxidative stress analysis, ELISA assay and western blot were used to investigate the role and underlying mechanisms of PF on healing in DFU. Our results showed that the STZ-induced diabetic rats had delayed wound healing compared with the normal rats, exhibited by intense oxidative DNA damage, low vascular endothelial growth factor (VEGF) and transforming growth factor ß1 (TGF-ß1) expression, as well as increased apoptosis. PF treatment activated the expression of nuclear factor-E2-related factor 2 (Nrf2) and improved wound healing in DFU rats. Our in vitro experiments confirmed that PF accelerated wound healing through the Nrf2 pathway under hyperglycemic conditions, with alleviated oxidative stress, increased cell proliferation and migration, decreased apoptosis, and increased the expression of VEGF and TGF-ß1. Our study demonstrates the therapeutic benefits of PF in diabetic wound healing, which provides a reference for future clinical trials using PF in DFU treatment.

Dysfunction of CD8 + PD-1 + T cells in type 2 diabetes caused by the impairment of metabolism-immune axis.

The metabolic changes and dysfunction in CD8 + T cells may be involved in tumor progression and susceptibility to virus infection in type 2 diabetes (T2D). In C57BL/6JJcl mice fed with high fat-high sucrose chow (HFS), multifunctionality of CD8 + splenic and tumor-infiltrating lymphocytes (TILs) was impaired and associated with enhanced tumor growth, which were inhibited by metformin. In CD8 + splenic T cells from the HFS mice, glycolysis/basal respiration ratio was significantly reduced and reversed by metformin. In the patients with T2D (DM), multifunctionality of circulating CD8 + PD-1 + T cells stimulated with PMA/ionomycin as well as with HLA-A*24:02 CMV peptide was dampened, while metformin recovered multifunctionality. Both glycolysis and basal respiration were reduced in DM, and glycolysis was increased by metformin. The disturbance of the link between metabolism and immune function in CD8 + PD-1 + T cells in T2D was proved by recovery of antigen-specific and non-specific cytokine production via metformin-mediated increase in glycolytic activity.

Angiotensin II Induces Increased Myocardial Expression of Receptor for Advanced Glycation End Products, Monocyte/Macrophage Infiltration and Circulating Endothelin-1 in Rats With Experimental Diabetes.

OBJECTIVES: It is known that the receptor for advanced glycation end products (RAGE) activation is involved in the pathogenesis of cardiovascular disease in diabetes. Previous studies have shown the presence of angiotensin II (Ang II) in diabetes, suggesting a role for this hormone during the disease. However, the association between RAGE and Ang II during pathologic cardiac remodelling after streptozotocin (STZ)-induced diabetes remains unclear. Because Ang II is capable of inducing pro-inflammatory events, blocking its production (enalapril), and its action on its receptor (losartan) could decrease inflammatory events in the myocardium in this experimental model of diabetes. Thus, the aim of this study was to assess the association between RAGE expression, inflammatory events and Ang II in the myocardium during STZ-induced diabetes. METHODS: Diabetes was induced by intravenous injection of STZ in Sprague-Dawley rats. Myocardial expressions of RAGE, monocyte/macrophage (ED-1-positive cells) infiltration and the intercellular adhesion molecule-1 were determined by histochemical methods. Levels of circulating endothelin-1 (ET-1) were determined by enzyme-linked immunoassay. Effects of Ang II included blocking using losartan (15 mg/kg body weight per day by gastric gavage) or enalapril (18 mg/kg body weight per day by gastric gavage). RESULTS: Increased expression of both RAGE and ED-1 was seen in the myocardium, but expression of myocardial vascular intercellular adhesion molecule-1 remained unchanged. Circulating levels of ET-1 in STZ rats were increased. Renin‒angiotensin system inhibition decreased expression of myocardial RAGE, ED-1 and ET-1. CONCLUSIONS: The present findings suggest a role for Ang II in myocardial inflammation in STZ-induced diabetes mediated by RAGE and ET-1.

MicroRNA-203a-3p regulates CoCl2-induced apoptosis in human retinal pigment epithelial cells by targeting suppressor of cytokine signaling 3.

PURPOSE: The apoptosis of human retinal pigment epithelial cells (RPEs) plays a critical role in the pathogenesis of diabetic retinopathy (DR), but the molecular mechanisms remain unclear. In this study, we explored the function of miR-203a-3p in CoCl2-induced RPEs apoptosis. METHODS: The cellular localization of miR-203a-3p was assessed by in situ hybridization. Luciferase reporter assays were performed to validate that suppressor of cytokine signaling 3(SOCS3) as a direct target of miR-203a-3p. Effects of miR-203a-3p manipulation on RPEs apoptosis were evaluated using TdT-mediated dUTP Nick-End Labeling (TUNEL) and Flow Cytometry. Expression levels of miR-203a-3p was analyzed by RT-PCR, the expression of target proteins was detected by western blot. RESULTS: miR-203a-3p was found to be located in the RPE layer of the retinas from normal and diabetic rats and SOCS3 was a direct target of miR-203a-3p. miR-203a-3p mimics resulted in improved CoCl2-induced apoptosis of RPEs, overexpression of SOCS3 or c-Jun N-terminal kinase (JNK) inhibitor SP600125 reversed the pro-apoptotic effect of miR-203a-3p, to a certain extent. CONCLUSIONS: Our data implied a crucial role of miR-203a-3p as a novel regulator of CoCl2-induced RPEs apoptosis through SOCS3. Deregulation of miR-203a-3p/SOCS3/JNK/c-Jun cascade thus may serve as an important contributor to RPEs apoptosis in DR.

Restoration of ß-Adrenergic Signaling and Activity of Akt-Kinase and AMP-Activated Protein Kinase with Metformin in the Myocardium of Diabetic Rats.

We studied the effect of metformin (100 and 200 mg/kg/day, 4 weeks) on the adenylyl cyclasestimulating effects of ß-agonists and relaxin in the myocardial membranes and on activities of Akt-kinase, an effector component of insulin signaling, and AMP-activated protein kinase (AMPK), a cellular energy sensor, in the myocardium of rats with type 2 diabetes mellitus induced by high-fat diet and streptozotocin. Metformin normalized the ratio of adenylyl cyclase effects of ß1/2- and ß3-agonists in the myocardial membranes, that is reduced in DM2, and restored phosphorylation of Akt-kinase by Ser473 and AMPK by Thr172 in the myocardium of diabetic rats. The effect of metformin in a dose of 200 mg/kg/day was more pronounced. Thus, the cardioprotective effect of metformin is due to its ability to restore the adrenergic and insulin regulation in cardiomyocytes and their energy status.

DhHP-6 ameliorates hepatic oxidative stress and insulin resistance in type 2 diabetes mellitus through the PI3K/AKT and AMPK pathway.

Insulin resistance is one major features of type 2 diabetes mellitus (T2DM). Deuterohemin-ßAla-His-Thr-Val-Glu-Lys (DhHP-6), a novel microperoxidase mimetic designed and synthesized based on microperoxidase 11 (MP-11), can scavenge reactive oxygen species (ROS) in vivo. In our previous studies, we showed that oral DhHP-6 could reduce blood glucose and improve insulin resistance. To investigate the mechanisms of how DhHP-6 ameliorates oxidative stress and insulin resistance, we established T2DM mouse models and glucosamine-induced HepG2 cell insulin resistance models. The results suggested that DhHP-6 decreased blood glucose, increased antioxidant enzyme activity, and inhibited glycogen synthesis in T2DM mice. In addition, DhHP-6 improved insulin resistance by activating phosphatidylinositol 3-kinase (PI3K)/AKT, and AMP-activated protein kinase (AMPK) pathway in T2DM mice. Furthermore, DhHP-6 also activated PI3K/AKT and AMPK pathway in glucosamine-induced HepG2 cells. However, LY294002 did not completely inhibit AKT phosphorylation, and partially inhibited AMPK phosphorylation, whilst compound C only partially reduced AMPK phosphorylation, and also partially inhibited AKT phosphorylation, suggesting that AKT and AMPK interact to improve insulin resistance. Thus, these data suggest that DhHP-6 attenuates insulin resistance via the PI3K/AKT and AMPK pathway.