Injection Of Streptozocin Research Articles

The antioxidant role of agomelatine and gallic acid on oxidative stress in STZ induced type I diabetic rat testes.

Diabetes is a multisystem disorder and its effects are observed on the reproductive system. One of the main causes of testicular tissue damage is diabetes-induced overproduction of reactive oxygen species and glycated end products. The main objectives of this study were to investigate the possible effects of agomelatine (AG) and gallic acid (GA) in suppressing oxidative stress in Type I diabetes induced testicular damage. A total of 28 adult male rats were included in the study. Diabetes was induced by intraperitoneal injection of streptozocin (STZ, 55mg/kg) to 21 rats, which were then randomly assigned to 3 groups; 1mL saline solution was given to the diabetes+saline group by oral gavage, 20mg/kg/day oral AG was given to the diabetes+AG group, and 20mg/kg/day oral GA was given to the diabetes+GA group for 4 weeks. Tumor necrosis factor α (TNFα), nitric oxide synthase 2 (NOS2), fibronectin and vascular endothelial growth factor (VEGF) were used for the investigation of inflammation, fibrosis and vascular structures. The terminal-deoxynucleoitidyl-transferase mediated nick end-labeling assay (TUNEL) was used to detect apoptosis. Testicular tissue total antioxidant capacity values were tested by biochemical analysis. AG treatment showed an improvement on biochemical parameters and histopathological appearance on the rat testes. GA showed dose-related regenerative effects on biochemical parameters. Histologically, a minimal healing effect was determined on the testes damage. In conclusion, it was observed that AG is a potentially beneficial agent for reducing testicular damage by decreasing oxidative stress level. However, GA was seen to have a poor therapeutic effect.

Tang-Luo-Ning Improves Mitochondrial Antioxidase Activity in Dorsal Root Ganglia of Diabetic Rats: A Proteomics Study.

Tang-luo-ning (TLN) is a traditional Chinese herbal recipe for treating diabetic peripheral neuropathy (DPN). In this study, we investigated mitochondrial protein profiles in a diabetic rat model and explored the potential protective effect of TLN. Diabetic rats were established by injection of streptozocin (STZ) and divided into model, alpha lipoic acid (ALA), and TLN groups. Mitochondrial proteins were isolated from dorsal root ganglia and proteomic analysis was used to quantify the differentially expressed proteins. Tang-luo-ning mitigated STZ-induced diabetic symptoms and blood glucose level, including response time to cold or hot stimulation and nerve conductive velocity. As compared to the normal, there were 388 differentially expressed proteins in the TLN group, 445 in ALA group, and 451 in model group. As compared to the model group, there were 275 differential proteins in TLN group and 251 in ALA group. As compared to model group, mitochondrial complex III was significantly decreased, while glutathione peroxidase and peroxidase were increased in TLN group. When compared with ALA group, the mitochondrial complex III was increased, and mitochondrial complex IV was decreased in TLN group. Together, TLN should have a strong antioxidative activity, which appears to be modulated through regulation of respiratory complexes and antioxidases.

Brain-derived neurotrophic factor and retinal ganglion cells in the retina of diabetic rat after intravitreal injection of human umbilical cord mesenchymal stem cells-induced neural stem cells

Objective To investigate the effect of intravitreal injection of neural stem cells (NSC) derived from human umbilical cord mesenchymal stem cells (hUCMSC) on the expression of brain-derived neurotrophic factor (BDNF) and the number of retinal ganglion cells (RGC). Methods Fifty-two adult male Sprague-Dawley rats were randomly divided into normal group (group A) and diabetes mellitus group which received intraperitoneal injection of streptozocin to make diabetic rat models. One month after the diabetic rat models were confirmed successfully, diabetic rats were randomly divided into diabetic group (group B), hUCMSC group (group C) and hUCMSC-induced NSC group (group D). And thirteen diabetic rats were included in each group. Immuno-cytochemistry was applied to observe BDNF and thymosin-1(Thy-1) staining in the retina. Then mean integrated absorbance of the staining region on the retina slices were analyzed by Image-Pro Plus 6.0. The number of Thy-1 labeled RGC was record. Results BDNF and Thy-1 were positive on the retina slices from group A. The staining intensity from group B became weak and the expression of BDNF and Thy-1 gradually decrease with time (P 0.05) at 2 weeks after injection, but were significant different for other time points (P<0.05). Significant positive correlation between the expression of BDNF and the number of RGC were found by the Pearson correlation analysis (r=0.964, P<0.05). Conclusion Intravitreal injection of hUCMSC-derived NSC to diabetic rat may protect the retina by promoting the expression of BDNF and increasing the number of RGC. Key words: Diabetic retinopathy/therapy; Neural stem cells/transplantation; Brain-derived neurotrophic factor; Retinal ganglion cells; Animal experimentation

Helix B surface peptide attenuates diabetic cardiomyopathy via AMPK-dependent autophagy

BackgroundErythropoietin (EPO) has been reported to exert protective effects on a host of damaged tissues. However, the erythropoietic effect of this hormone can result in high risks of thrombosis, stroke, and hypertension, remarkably limiting the clinical use of EPO. Helix B surface peptide (HBSP) is a small peptide derived from the helix-B domain of EPO. Surprisingly, HBSP retains the tissue protective properties of EPO without altering the hematocrit. Thus, we evaluated the possible role of HBSP on diabetic cardiomyopathy. MethodsDiabetes was induced in mice by intraperitoneal injections of streptozocin (STZ). Mice were randomly treated with normal saline or HBSP. Cardiac function, fibrosis, apoptosis, and myocardial mitochondrial morphology were examined. For in vitro experiments, H9C2 myoblast cells were randomly grouped as normal glucose (NG, 5 mM), NG+HBSP (100 nM), high glucose (HG, 33 mM), HG+HBSP (100 nM), HG+HBSP+3-methyladenine (3-MA, 10 mM), HG+rapamycin (Rapa, 100 nM), and HG+HBSP+Compound C (CC, 10 mM). Autophagosomes, LC3 dots, apoptosis and mitochondria membrane potential (MMP) of H9C2 cells were examined.The expressions of LC3, p62, p-AMPK (Thr172) and p-mTOR (Ser2448) were examined by Western blot. ResultsHBSP markedly improved cardiac function, attenuated cardiac interstitial fibrosis, inhibited myocardial apoptosis, and ameliorated mitochondrial ultrastructure in mice with diabetic cardiomyopathy. HG reduced autophagy in H9C2 cells. HBSP enhanced autophagy in HG-treated H9C2 cells. HBSP reduced the apoptosis index of HG-treated H9C2 cells. HBSP increased the MMP of HG-treated H9C2 cells. HBSP increased the levels of p-AMPK (Thr172), and reduced p-mTOR (Ser2448) in HG-treated H9C2 cells, and the increase of p-AMPK (Thr172) was accompanied by the stimulation of autophagy. Autophagy inhibitor 3-MA and AMPK inhibitor CC mitigated HBSP-induced beneficial effect, whereas autophagy inducer Rapa alleviated the HG-induced cell apoptosis. ConclusionsHBSP attenuates diabetic cardiomyopathy via autophagy mediated by AMPK-dependent pathway. HBSP may be a potential therapeutic intervention for diabetic cardiomyopathy.

Alterations of mTOR pathway and autophagy in early type 2 diabetic cardiomyopathy in rats

Objective: To investigate the alterations of mTOR signaling pathway and autophagy in the development of type 2 diabetes and early diabetic cardiomyopathy and to study their roles in pathogenesis of diabetic myocardium. Methods: A type 2 diabetes rat model was established by injection of streptozocin after five-week of high fat diet. The rats were randomly divided into control group, experiment group of 2 weeks and experiment group of 4 weeks. Alterations of mTOR, p-mTOR, S6K1, Beclin-1 and LC3-Ⅱ expression in myocardium were determined by Western blot and immunohistochemistry. Results: Compared with the control group, the expression of mTOR, p-mTOR, S6K1, Beclin-1 and LC3-Ⅱ level increased significantly in the experiment group of 2 weeks. The expression of p-mTOR and S6K1 increased significantly in the experiment group of 4 weeks compared with those of the experiment group of 2 weeks. Conclusions: mTOR signaling pathway is activated in early diabetic myocardial injury via autophagy. The findings may provide a new therapeutic target for diabetic cardiomyopathy.

Effects of a treatment with Se-rich rice flour high in resistant starch on enteric dysbiosis andchronic inflammation in diabetic ICR mice.

Enteric dysbiosis is associated with chronic inflammation and interacts with obesity and insulin resistance. Obesity and diabetes are induced in ICR (Institute of Cancer Research) mice fed a high-fat diet and administered a streptozocin injection. These mice were treated with normal rice (NR), normal rice with a high resistant starch content (NRRS) or Se-rich rice (selenium-enriched rice) with a high resistant starch content (SRRS). Faecal cell counts of Bifidobacterium, Lactobacillus and Enterococcus were significantly higher in SRRS-treated mice than in diabetic controls, while Enterobacter cloacae were lower. Similar results were also found in NRRS-treated mice. In contrast, no significant difference was found between NR-treated and diabetic control groups. The treatments with SRRS and NRRS reduced the faecal pH values of the diabetic mice. Regarding the inflammatory factor levels, lower levels of serum C-reactive protein (CRP), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), nuclear factor-k-gene binding (NF-κB) and leptin (LEP) and higher adiponutrin (ADPN) levels were found in the SRRS and NRRS-treated mice compared with the diabetic and NR-treated mice. In addition, the CRP, IL-6 and NF-κB levels in the SRRS-treated mice were significantly reduced compared with those observed in the NRRS-treated mice. The reverse transcription-PCR (RT-PCR) results showed that the SRRS and NRRS-treated mice presented higher expression levels of orphan G protein-coupled receptor 41 (GPR41) and orphan G protein-coupled receptor 43 (GPR43) proteins compared with diabetic mice and NR-treated mice. These results indicate that treatments with rice high in RS exert beneficial effects by improving enteric dysbiosis and chronic inflammation. In addition, selenium and RS may exert synergistic effects on chronic inflammation. © 2016 Society of Chemical Industry.

Association of Bactericidal Dysfunction of Paneth Cells in Streptozocin-Induced Diabetic Mice with Insulin Deficiency.

BackgroundType 1 diabetes mellitus (T1DM) is associated with increased risks of enteric infection. Paneth cells constitute the first line of the gut defense. Little is known about the impact of T1DM on the bactericidal function of intestinal Paneth cells.Material/MethodsA T1DM mouse model was induced by intraperitoneal injection of streptozocin. The analysis of intestinal microbiota and the mucosal bactericidal assay were conducted to evaluate intestinal innate defense. Numbers of Paneth cells and their expression of related antimicrobial peptides were analyzed. Expression of total insulin receptor (IR) mRNA and relative levels of IR-A/IR-B were analyzed. The primary mouse small intestinal crypt culture was used to analyze the effect of insulin and glucose on the expression of related antimicrobial peptides of Paneth cells.ResultsIn T1DM mice, bacterial loads were increased and there was an alteration in the composition of the intestinal microflora. Exogenous bacteria had better survival in the small bowel of the T1DM mice. The expression of Paneth cell-derived antimicrobial peptides was significantly decreased in the T1DM mice, although the number of Paneth cells was increased. Relative levels of IR-A/IR-B in Paneth cells of diabetic mice were elevated, but the total IR mRNA did not change. Insulin treatment restored the expression of antimicrobial peptides and normalized the microbiota in the gut of T1DM mice. Subsequently, in vitro culture assay demonstrated that insulin rather than glucose was essential for the optimal expression of Paneth cell-derived antimicrobial peptides.ConclusionsThe bactericidal function of intestinal Paneth cells was impaired in STZ-induced diabetic mice, resulting in the altered intestinal flora, and insulin was essential for the optimal expression of Paneth cell-derived antimicrobial peptides.

Effect of the oral iron chelator deferiprone in diabetic nephropathy rats.

The aim of the present study was to investigate the effects of the iron chelator deferiprone in diabetic nephropathy (DN) rats and the mechanisms involved. Thirty-two male Wistar rats (180-220 g, 6 weeks old) were randomly divided into a control group, a DN group and two DN groups treated with either 50 or 100 mg/kg per day deferiprone. The DN group was established by feeding of a high-carbohydrate-fat diet and injection of 35 mg/kg streptozotocin into the vena caudalis. The duration of deferiprone treatment was 20 weeks. Histopathological changes were detected by hematoxylin-eosin and Masson staining, as well as transmission electron microscopy. Levels of nuclear factor (NF)-κB, monocyte chemotactic protein (MCP)-1, matrix metalloproteinase (MMP)-9, tissue-specific inhibitor of metalloproteinase (TIMP)-1, cyclo-oxygenase (COX)-2, and nitrotyrosine were determined in kidney tissues using reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunohistochemistry. Histopathological observations showed that deferiprone treatment alleviated inflammation infiltrates and collagenous fibrosis in DN rats. Results from RT-PCR and western blotting indicated that deferiprone inhibited the expression of NF-κB, MCP-1, COX-2, and nitrotyrosine, which were overexpressed in DN rats. Immunohistochemistry showed that the mechanism of deferiprone action may involve regulation of MMP-9 and TIMP-1. Decreased MMP-9 expression and increased TIMP-1 expression in DN rats were significantly promoted and inhibited by deferiprone, respectively. Iron chelation by oral deferiprone has a renoprotective effect in DN rats by relieving oxidative stress, inflammation, and fibrosis, which is related to the cytokines NF-κB, MCP-1, MMP-9, TIMP-1, COX-2, and nitrotyrosine.

EFFECT OF α-LIPOIC ACID IN INHIBITING OXIDATIVE STRESS AND PROMOTING DIABETIC WOUND HEALING BY SUPPRESSING EXPRESSION OF miR-29b IN MICE

To investigate the effect of α-lipoic acid on the oxidative stress of wound tissues and diabetic wound healing in mice with diabetic feet. Sixty male C57BL/6J mice weighting 200-300 g were randomly divided into model group (control group, n=15), α-lipoic acid-treated model group (n=15), miR-29b mimic group (n=15), and miR-29b mimic negative control group (NC group, n=15). All animals received intraperitoneal injection of streptozocin to establish the diabetic model. Then, a full thickness wound of 5 mm×2 mm in size was created at 4 weeks after modeling. All mice were administrated with high-sugar-fat-diet. At the same day after modeling, α-lipoic acid-treated model group was continuously given intravenous injection of 100 mg/(kg·d) α-lipoic acid for 14 days; miR-29b mimic group and NC group received the tail intravenous injection of lentiviral vector for miR-29b mimic and miR-29b mimic negative control (a total of 2×107 TU), respectively, with the treatment of α-lipoic acid. The wound healing was observed and wound area was measured at 7 and 14 days. The wound tissues were harvested to detect the levels of superoxide dismutase (SOD) and glutathione (GSH) using xanthine oxidase method and 5, 5-dithiobis-2-nitrobenzoic acid staining method at 14 days. At the same day, 7, and 14 days after modeling, the relative miR-29b expression in wound tissues from control and α-lipoic acid-treated model groups was detected by real-time fluorescence quantitative PCR. All mice survived to the experiment end. The wound healing was faster in α-lipoic acid-treated group than control group. At 7 and 14 days, the relative wound area and miR-29b expression level were significantly lower, while the contents of SOD and GSH were significantly higher in α-lipoic acid-treated group than control group (P<0.05). In addition, miR-29b mimic group had significantly increased relative wound area and significantly decreased the contents of SOD and GSH when compared with NC group at 7 and 14 days (P<0.05). α-lipoic acid could inhibit oxidative stress and promote diabetic wound healing by suppressing expression of miR-29b in mice.

Abstract 305: Carvacrol Attenuates Diabetic Cardiomyopathy by Enhancing PI3K/AKT Pathway in STZ-induced Type 1 Diabetic C57BL/6J Mice

Background: Carvacrol (CAR), a monoterpenic phenol that occurs in many essential oils of the family Labiatae including Origanum , Satureja , Thymbra , Thymus , and Corydothymus species, possess a wide variety of pharmacological properties including antioxidant and anti-inflammatory potential. This present study was designed to investigate the cardiac protective effect of CAR on diabetic cardiomyopathy in STZ-induced type 1 diabetic mice and explore its potential molecular mechanism. Methods: Type 1 diabetes was induced by the intraperitoneal injection of streptozocin (STZ) to male mice at dose of 45 mg/kg body weight (BW). The diabetic animals were divided into three groups containing eight in each: Group I diabetes, Group II and II injected with CAR at 10 and 20 mg/kg BW respectively once daily for 6 weeks. Age matched male C57 mice were used as normal controls. The plasma concentrations of glucose, total cholesterol (TC) and triglycerides (TG) levels were enzymatically determined using commercial kits. The cardiac function was measured by echocardiography. Protein levels of p-PDK1/t-PDK1, p-AKT/t-AKT, p-GSKα/β/t-GSKα/β were detected by Western blotting. Results: STZ-induced C57BL/6J diabetic mice showed an elevation in serum glucose, TG and TC level. Compared to diabetic mice, administration of CAR resulted in significant decrease ( P &lt;0.05) in plasma glucose level in a dose dependent manner, but did not attenuate elevation in TG and TC levels. The abnormal diastolic function in type 1 diabetic mice was significantly reversed by CAR administration. Furthermore, western blotting showed that the expression of p-PDK1, p-AKT and p-GSKα/β were lower in diabetic hearts than C57 hearts while total PDK1, AKT and GSK α/β protein levels were no difference among groups. CAR administration attenuated these decreases in protein phosphorylation. These findings indicate that the impaired PI3K/AKT pathway induced by STZ in diabetic heart can be restored by CAR. Conclusion: Carvacrol has antidiabetic property and can be potentially used to prevent hyperglycemia and diabetic cardiomyopathy.

The effect of Liuwei Dihuang decoction on PI3K/Akt signaling pathway in liver of type 2 diabetes mellitus (T2DM) rats with insulin resistance

Ethnopharmacological relevanceLiuwei Dihaung decoction (LWDHT) is a well-known classic traditional Chinese medicine formula, consists of six herbs including Rehmannia glutinosa Libosch.(family: Scrophulariaceae), Cornus officinalis Sieb.(family: Cornaceae), Dioscorea opposite Thunb.(family: Dioscoreaceae), Alisma orientale(G. Samuelsson) Juz (family: Alismataceae), Poria cocos (Schw.) Wolf (family: Polyporaceae) and Paeonia suffruticosa Andrews (family: Paeoniaceae). It has been used in the treatment of many types of diseases with signs of deficiency of Yin in the kidneys in China clinically. This study is aimed at investigating the effect of Liuwei dihuang decoction on PI3K/Akt signaling pathway in liver of T2DM rats with insulin resistance. Materials and methodsT2DM model was induced in male Sprague-Dawley (SD) rats by high sugar and high fat diets combined with small dose of streptozocin (STZ) injection. The successful T2DM rats were randomly allocated three group--vehicle group, positive control group and Liuwei Dihuang decoction group. After 12-weeks treatment with distilled water, rosiglitazone and LWDHT by intragastric administration respectively, the rats were put to death in batches. The variance of fasting blood glucose (FBG) and fasting insulin (FINS) in serum were determined, the pathological changes of each rats’ liver were observed by hematoxylin-eosin (HE) staining, the expression of insulin receptor substrate 2(IRS2), phosphatidylinositol 3-kinase (PI3K) and protein kinas B (Akt) involving the canonical PI3K/Akt signaling pathway were detected by Real-time fluorescent quantitative PCR (RT-PCR), and the expression level of IRS2, PI3K, Akt protein and phosphorylated IRS2, PI3K, Akt protein were evaluated by Western Blot. All the data were analyzed by SPSS 17.0. ResultsFour weeks of treatment with LWDHT could significantly decrease the level of FBG and FINS in serum, improve the cellular morphology of liver, kidney, pancreas tissue, and the expression of IRS2, PI3K, Akt mRNA and phosphorylated IRS2, PI3K, Akt protein involved in the canonical PI3K/Akt signaling pathway of T2DM rats in liver were significantly up-regulated, while the total IRS2, PI3K, and Akt protein had no obvious changes. ConclusionsThe results suggest that Liuwei Dihuang decoction could intervene insulin resistance of T2DM, in part, through regulation of canonical PI3K/Akt signaling pathway of T2DM rats in liver.

Involvement of the NF-κB signaling pathway in the renoprotective effects of isorhamnetin in a type 2 diabetic rat model.

The aim of the present study was to investigate the renoprotective effects of isorhamnetin (ISO) in type 2 diabetic rats and its effects on the nuclear factor-κB (NF-κB) signaling pathway, which is associated with diabetic nephropathy. The type 2 diabetic rat model was established by a high-fat diet plus streptozocin injection and the rats were subsequently treated with two dosages of ISO, respectively. The levels of blood glucose were determined. Urinary osteopontin, kidney injury molecule-1 (KIM-1) and albumin were measured to evaluate the renal function of the rats. Renal NF-κB signaling activity was assessed by measuring the levels of NF-κB p65, phospho-NF-κB p65, inhibitor of NF-κB (IκBα) and phospho-IκBα, and the NF-κB p65 DNA-binding activity. Downstream inflammatory mediators [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-β1 (TGF-β1)] of the NF-κB signaling pathway were investigated to evaluate the renal inflammatory response. Renal levels of malondialdehyde and total superoxide dismutase were detected to access the oxidative stress. Furthermore, glomerular mesangial cells (GMCs) were treated with lipopolysaccharide and ISO. In the cellular experiment, the NF-κB signaling activity, levels of TNF-α, IL-1β, IL-6, ICAM-1 and TGF-β1, and oxidative stress were also investigated. The results showed that ISO decreased the levels of urinary osteopontin, KIM-1 and albumin. ISO also inhibited the NF-κB signaling activity, decreased the production of inflammatory mediators and attenuated oxidative stress in diabetic rats and GMCs. The present investigations revealed that ISO had ameliorative effects on diabetes-induced renal damage and the activity may be associated with the negative regulation of NF-κB signaling pathway.

Gossypol ameliorates liver fibrosis in diabetic rats induced by high-fat diet and streptozocin

11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) inhibitors have been shown to treat type 2 diabetes (T2D). Since gossypol is an 11β-HSD1 inhibitor, the objective of the present study was to treat T2D and T2D-related liver fibrosis in rat model using low-dose gossypol. T2D was induced by feeding with high fat diet plus injection of streptozocin (30mg/kg). Diabetic rats were treated with either vehicle control or racemic gossypol with a dose of 15mg/kg/day for 4weeks followed by 15mg/kg/week for additional 8weeks. Blood glucose, cholesterol, LDL, and triglycerides were measured. Messenger mRNA levels of glucocorticoid receptor (Nr3c1), phosphoenolpyruvate carboxykinase (Pck1), glucose-6-phosphatase (G6pc), collagen I (Col1a1), collagen III (Col3a1), fibronectin (Fn1), tissue inhibitor of metalloproteinase 1 (Timp1), and 2 (Timp2) were measured. T2D rats had higher serum glucose, cholesterol, LDL, and triglyceride levels compared to control. Liver Nr3c1, Col1a1, Col3a1, Fn1, Timp1, and Timp2 were increased in T2D rats. T2D liver showed significant fibrosis with the increases of α-smooth muscle actin and fibronectin. After gossypol treatment, serum glucose level was lowered by 64%. Liver fibrosis was significantly ameliorated. Nr3c1, Col1a1, Col3a1, Fn1, Timp1, Timp2, Pck1 as well as G6pc levels were significantly reduced. In conclusion, low dose gossypol is effective for the treatment of T2D and T2D-related fibrosis.

Resveratrol ameliorates myocardial fibrosis by inhibiting ROS/ERK/TGF-β/periostin pathway in STZ-induced diabetic mice.

BackgroundMyocardial fibrosis is an essential hallmark of diabetic cardiomyopathy (DCM) contributing to cardiac dysfunctions. Resveratrol, an antioxidant, exerts its anti-fibrotic effect via inhibition of oxidative stress, while the underlying molecular mechanism remains largely elusive. Periostin, a fibrogenesis matricellular protein, has been shown to be associated with oxidative stress. In the present study, we investigated the role of periostin in anti-fibrotic effect of resveratrol in streptozocin (STZ)-induced diabetic heart and the underlying mechanisms.MethodsDiabetic mice were induced by STZ injection. After treatment with resveratrol (5 or 25 mg/kg/day i.g) or Saline containing 0.5 % carboxymethyl cellulose (CMC) for 2 months, the hearts were detected for oxidative stress and cardiac fibrosis using western blot, Masson’s trichrome staining and Dihydroethidium (DHE) staining. In in vitro experiments, proliferation and differentiation of fibroblasts under different conditions were investigated through western blot, 3-(4,5)-dimethylthiahiazo (−z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay and immunofluorescence staining.ResultsAdministration of resveratrol significantly mitigated oxidative level, interstitial fibrosis and expressions of related proteins in STZ-induced diabetic hearts. In in vitro experiments, resveratrol exhibited anti-proliferative effect on primary mouse cardiac fibroblasts via inhibiting reactive oxygen species (ROS)/extracellular regulated kinase (ERK) pathway and ameliorated myofibroblast differentiation via suppressing ROS/ERK/ transforming growth factor β (TGF-β)/periostin pathway.ConclusionIncreased ROS production, activation of ERK/TGF-β/periostin pathway and myocardial fibrosis are important events in DCM. Alleviated ROS genesis by resveratrol prevents myocardial fibrosis by regulating periostin related signaling pathway. Thus, inhibition of ROS/periostin may represent a novel approach for resveratrol to reverse fibrosis in DCM.

Evaluation of the effects of new peptide compounds in experimental animals with a toxic model of Alzheimer’s disease

Development of new approaches to the treatment of Alzheimer’s disease (AD) is an actual problem of modern neurology owing to high prevalence of AD in the population and severe irreversible disability resulting from this disease. We investigated the effects of new peptide compounds, β-casomorphin-7 and colostrinin, in two complementary AD models in rats (with injection of β-amyloid into the nucleus basalis of Meynert and injection of streptozocin in the ventricles of the brain). Peptides were injected intranasally within 10 days after the onset of AD symptoms induced by neurotoxins. Injection of β-casomorphin-7 and colostrinin had similar effect on the behavior and cognitive function of rats with both amyloid and streptozocin AD model: there was statistically significant increase in locomotor activity and orienting responses, as well as improvement of animals’ cognitive functions. Colostrinin had stronger positive effect on the behavior of rats with induced AD, whereas β-casomorphin-7 had an effect on both sham-operated and model animals, which is indicative of the general neurotropic potential of this peptide. The proposed experimental approaches improve the capabilitiesof investigation of novel biologically active compounds aimed at prevention and treatment of neurodegenerative diseases.

Effects of crocin on experimental obesity and type-2 diabetes.

The aim of this study is to scrutinize the effects of crocin on obesity and type-2 diabetes, with an approach that takes oxidative stress and inflammatory parameters into account. The experimental obesity model was created by utilizing a 10-week-long high-fat diet (HFD). An experimental type-2 diabetes model was created by injecting multiple low-dose streptozocin (STZ) injections into rats that were fed with the HFD. The treatment groups were administered a daily crocin dose of 150 mg/kg for 6 weeks via gavage. Findings of the study demonstrated that crocin could be effective in relieving the symptoms of obesity and diabetes (hyperinsulinemia, hyperleptinemia, insulin resistance, and weight gain). It was determined that crocin lowered the plasma TNF-α and IL-1β levels and the pancreas tissue TNF-α and IFN-γ levels, which were increased due to diabetes, and reduced the inflammation in diabetic rats. Similarly, it was found that oxidative stress, which increased due to the progress of diabetes, was reduced in crocin treatment group. Crocin could contribute to the development of phytotherapeutic approaches in the treatment of obesity, diabetes, and diabesity (obesity-induced diabetes), which is promising as the abovementioned incidences have increased considerably in today's world.

GSK-3beta Inhibitor Induces Expression of Nrf2/TrxR2 Signaling Pathway to Protect against Renal Ischemia/Reperfusion Injury in Diabetic Rats

Background/Aims: Diabetes mellitus (DM) can lead to renal damage and dysfunction, and exacerbate renal ischemia/reperfusion injury (RI/RI). The aim of this study was to investigate the protective effect of GSK-3β inhibitor TDZD-8 against RI/RI through Nrf2/TrxR2 signaling pathway in a rat DM model. Methods: A DM rat model was established by a single injection of streptozocin. Diabetic rats were pretreated with TDZD-8 (1 mg/kg bw) or TDZD-8+auranofin (10 nmol/L, 5ml/kg bw), and then subjected to 45-min ischemia and 24-h reperfusion. Rats were equally randomized into four groups: a Sham-operated group, a RI/RI group, a TDZD-8 group, and a TDZD-8+auranofin group. Serum levels of BUN and Scr were measured. SOD activity, MDA content, and Nrf2, TrxR2 and caspase-3 expressions in rat kidney tissues were determined. Results: Renal function was improved, oxidative stress and cell apoptosis were reduced, and the expression of Nrf2 and TrxR2 was up-regulated in TDZD-8 treated rats as compared with those in auranofin treated rats. Conclusion: TDZD-8 may exert its protective effect against RI/RI by regulating the Nrf2/TrxR2 signaling pathway in the kidney tissue in DM.

Attenuation of Endoplasmic Reticulum Stress-Mediated Liver Damage by Mulberry Leaf Diet in Streptozotocin-Induced Diabetic Rats.

Endoplasmic reticulum stress (ERS) plays a crucial role in the development of insulin resistance and diabetes mellitus. Although antidiabetic use of mulberry leaves (MLs) has been popular due to their many anti-oxidative flavonoid compounds and free radical scavenging effects, ML's effects on ERS in experimental diabetic hepatocyte injury remain unknown. To investigate how ML affect ERS in diabetic liver, Sprague-Dawley (SD) rats were assigned to induce diabetes by a single intraperitoneal injection of streptozocin (STZ; 55 mg/kg) and fed with either normal chow or a diet containing 25% mulberry leaf powder diet (MLD) and examined for 56 days. We observed that MLD improved the rats' morphological and histopathological changes. Levels of ERS markers such as phosphorylated double-stranded RNA-dependent protein kinase-like endoplasmic reticulum kinase (PERK) and X-box binding protein 1 (XBP1) and the protein expression of glucose regulated protein 78 (GRP78) were significantly higher in the diabetic liver compared to normal liver. MLD for 8 weeks significantly reduced all of these markers. MLD also significantly decreased hepatocyte apoptosis, hepatic macrophage recruitment, cellular infiltration, and CCAAT/enhancer-binding protein homologous protein (CHOP), tumor necrosis factor receptor associated factor 2 (TRAF2), interleukin 1[Formula: see text] (IL-1[Formula: see text]) and sterol regulatory element binding protein isoform 1c (SREBP 1c) levels in diabetic liver. These results may suggest that MLs can preserve hepatic function in experimental diabetes by modulating ERS mediated apoptosis and liver damage.

Dynamic Changes of Betatrophin and Its Potential Effect on β-cells in Spontaneously Developed or Streptozocin-induced Diabetes Monkeys

Effects of betatrophin on β-cell proliferation and insulin secretion have been reported controversially in rodent studies. This study was to investigate the dynamic changes of betatrophin and its potential effect on β-cell function in non-human primates (NHPs). Blood betatrophin levels in naturally developed diabetes cynomolgus monkeys (n=65) significantly correlated with their body weights and blood glucose levels in the females (n=20) and with insulin and C-peptide levels in the males (n=45). Liver expression of betatrophin mRNA was markedly higher in spontaneously developed diabetes monkeys than in normoglycemic ones. Its liver expression correlated well with islet size and insulin content in normoglycemic cynomolgus monkeys and also well in spontaneously hyperglycemic (>200 mg/ dL) cynomolgus monkeys with high blood insulin level, but not well in those with very low blood insulin content. Both blood glucose and betatrophin increased dramatically in normoglycemic rhesus monkeys (n=7) after streptozocin (STZ) administration. Blood insulin initially increased on day 1 after STZ dosing and then decreased dramatically. Two NHPs with blood glucose back to ~80 mg/mL on day 14 after STZ injection showed recovery of insulin secretion. In another two STZ-treated NHPs with blood glucose >250 mg/dL, apparent proliferation of both β-cells and non-β- cells was observed in their islets. The rest NHPs with more completed β-cell destruction after STZ dosing showed much higher blood glucose (>300 mg/dL) with very low insulin and no obvious β-cell proliferation. Our results indicate that NHP liver expresses abundant betatrophin mRNA. As its levels correlated well with islet size and insulin content in some diabetic NHPs, it might play a role in β-cell proliferation. Our data are consistent with the clinical finding of the elevation of circulating betatrophin in patients with type 2 diabetes. In addition, betatrophin-enhanced β-cell proliferation seems requiring a minimal base level of pancreatic β-cells and islets.

The skin remodeling in type 1 diabetes and insulin resistance animal models.

The skin matrix metalloproteinase 3, tissue inhibitors of matrix metalloproteinase 2 and collagen III content changes in type 1 diabetes and insulin resistance treated with insulin and metformin were studied. Healthy adult male Wistar rats were obtained from experimental animal house, Department of Experimental Pharmacology, Medical University in Bialystok. The rats were divided randomly into five groups of 8 rats each. Control rats were injected intraperitoneally by NaCl. Type IDDM was induced by a single injection of Streptozocin. Insulin resistance was induced by a high-fat diet. The chosen groups of rats were also treated with insulin or metformin. ELISA Kits (USCN Life Science, China) were used to measure content of matrix metallo-proteinase 3 (ELISA Kit for Matrix Metalloproteinase 3 - MMP3), tissue inhibitor of matrix metalloproteinase 2 (ELISA Kit for Tissue Inhibitors of Metalloproteinase 2 - TIMP2) and content of collagen type 3 (ELISA Kit for Collagen Type III - COL3). The results were reported as a median. The statistical significance was defined as p<0.05. Type 1 diabetes and insulin resistance have significantly reduced the quality of the skin, shown by the increase in content of matrix metalloproteinase 3 and the decrease in content of tissue inhibitors of matrix metalloproteinase 2. Type 1 diabetes and insulin resistance have reduced the quality of the skin expressed by type III collagen content decrease but for future studies it is recommend to determine rat interstitial collagenase, MMP-13, as well. Insulin and metformin treatment improved the quality of the diabetic skin, demonstrated by the type III collagen content increase.