Rat Model Of Type Research Articles

G protein-coupled receptor kinase 2 inhibition improves erectile function through amelioration of endothelial dysfunction and oxidative stress in a rat model of type 2 diabetes.

Type 2 diabetes mellitus (T2DM) is a common cause of erectile dysfunction (ED). It has been demonstrated that G protein-coupled receptor kinase 2 (GRK2) overexpression contributes to diabetic endothelial dysfunction and oxidative stress, which also underlies ED in T2DM. We hypothesized that GRK2 overexpressed and attenuated endothelial function of the cavernosal tissue in a rat model of T2DM. T2DM rats were established by feeding with a high-fat diet (HFD) for 2 weeks and then administering two intraperitoneal (IP) injections of a low dose of streptozotocin (STZ), followed by continuous feeding with a HFD for 6 weeks. GRK2 was inhibited by IP injection of paroxetine, a selective GRK2 inhibitor, after STZ injection. Insulin challenge tests, intracavernous pressure (ICP), GRK2 expression, the protein kinase B (Akt)/endothelial nitric oxide synthase (eNOS) pathway, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit gp91phox, nitric oxide (NO), reactive oxygen species (ROS) production, and apoptosis in cavernosal tissue were examined. Less response to insulin injection was observed in T2DM rats 2 weeks after HFD. Markedly increased GRK2 expression, along with impaired Akt/eNOS pathway, reduced NO production, increased gp91phox expression and ROS generation, increased apoptosis and impaired erectile function were found in T2DM rats. Inhibition of GRK2 with paroxetine ameliorated Akt/eNOS signaling, restored NO production, downregulated NADPH oxidase, subsequently inhibited ROS generation and apoptosis, and ultimately preserved erectile function. These results indicated that GRK2 upregulation may be an important mechanism underlying T2DM ED, and GRK2 inhibition may be a potential therapeutic strategy for T2DM ED.

O-GlcNAc-modified SNAP29 inhibits autophagy-mediated degradation via the disturbed SNAP29-STX17-VAMP8 complex and exacerbates myocardial injury in type I diabetic rats.

The O-linked β-N-acetylglucosamine (O-GlcNAc) modification and autophagy are associated with diabetic myocardial injury, however, the molecular mechanisms between the two processes remain to be fully elucidated. The purpose of the present study was to elucidate the molecular regulation of autophagy by O-GlcNAc-modified synaptosomal-associated protein 29 (SNAP29) in diabetic myocardial injury. A rat model of type I diabetes was established via intraperitoneal injection of streptozotocin (STZ; 55 mg/kg). Significant increases in the O-GlcNAc modification and accumulation of the autophagy markers microtubule-associated protein 1 light chain 3α II/I and P62, which suggest that autophagic flux is inhibited, were observed in rats 8 weeks following STZ induction. Subsequently, the selective O-GlcNAcase inhibitor, thiamet G, increased the level of O-GlcNAc modification, which further disrupted autophagic flux; deteriorated cardiac diastolic function, as indicated by an increased left ventricular filling peak velocity/atrial contraction flow peak velocity ratio shown by echocardiography; and exacerbated myocardial abnormalities, as characterized by cardiomyocyte disorganization and fat and interstitial fibrosis accumulation. By contrast, 6-diazo-5-oxo-L-norleucine, an inhibitor of glucosamine fructose-6-phosphate aminotransferase isomerizing 1, acted as an O-GlcNAc antagonist and reduced the level of O-GlcNAc modification, which maintained autophagic flux and improved cardiac diastolic function. In vitro, high glucose (25 mM) was used to stimulate primary neonatal rat cardiomyocytes (NRCMs). Consistent with the myocardium of diabetic rats, it was also shown in the NRCMs that O-GlcNAc modification of SNAP29 negatively regulated autophagic flux. The application of the short hairpin RNA interference lysosome-associated membrane protein (LAMP2) and the autophagy inhibitor 3-methyladenine demonstrated that high glucose inhibited autophagy-mediated degradation rather than affected the initial stage of autophagy. Finally, co-immunoprecipitation was used to determine the role of the O-GlcNAc-modified substrate protein SNAP29, which acted as an SNAP29-syntaxin-17 (STX17)-vesicle-associated membrane protein 8 (VAMP8) complex during disease progression. The present study is the first, to the best of our knowledge, to demonstrate that SNAP29 is an O-GlcNAc substrate and that an increase in O-GlcNAc-modified SNAP29 inhibits SNAP29-STX17-VAMP8 complex formation, thereby inhibiting the degradation of autophagy and exacerbating myocardial injury in type I diabetic rats.

Effect of hydroalcohol extract of lemon (<i>Citrus limon</i>) peel on a rat model of type 2 diabetes

Purpose : To determine the effect of the hydroalcohol extract of lemon peel (LP) on a rat model of type 2 diabetes (T2D). Method : The rat model of T2D by injection of streptozotocin was established. The effects of a hydroalcoholic extract of LP was characterised on a rat model of type 2 diabetes based on body weight, food intake, fasting blood glucose (FBG), glucose tolerance test, and insulin tolerance test. Antioxidant activity and oxidative stress were analysed by superoxide dismutase (SOD) and malonaldehyde (MDA) assays. Results : In acute toxicity studies, administration of LP extract at 2000 mg/kg orally did not cause any symptoms of poisoning or death after 14 days. The body weight of rats increased after treatment with LP extracts. Food intake in diabetic rats decreased with LP extract treatment. Continual treatment with LP extracts for 35 days significantly reduced blood glucose levels in diabetic rats. Glucose tolerance improved, and insulin resistance was reduced after treatment with LP extracts. SOD and MDA data indicate that treatment with LP extract alleviated the oxidative stress in diabetic rats as well as enhanced the antioxidant activity of liver in a dosage-dependent manner. Conclusion : LP extract decreased food intake and FBG, but increased body weight in rats. The effect of LP on T2D is likely related to improved antioxidant activity and reduced oxidative stress. Thus, LP extract has potentials for the treatment of T2D. Keywords : Lemon peel, Type 2 diabetes, Antioxidant activity, Glucose tolerance, Insulin tolerance

Anti-diabetic activity of aqueous extract of Fructus Ligustri Lucidi in a rat model of type 2 diabetes

Purpose : To determine the anti-diabetic activity of an aqueous extract of Fructus Ligustri Lucidi (FLL) in a rat model of type 2 diabetes (T2D). Method : Body weight (BW), food intake (FI), fasting blood glucose (FBG), glucose tolerance testing and insulin tolerance testing were used to determine the anti-diabetic activity of an aqueous extract of Fructus Ligustri Lucidi (FLL) in a rat model of streptozotocin-induced T2D. Anti-oxidant activity and oxidative stress were assessed by superoxide dismutase (SOD) and malondialdehyde (MDA) analyses, respectively. Results : Following FLL extract treatment, diabetic rat BW increased, while FI and FBG levels decreased. FLL extract increased glucose tolerance and decreased insulin tolerance. Following treatment with 300 and 600 mg/kg FLL extract, MDA levels reached 13.5 ± 0.9 nmol/ml and 13.8 ± 1.1 nmol/ml, respectively. Compared to MDA levels of 19.5 ± 1.1 nmol/ml in diabetic control group, MDA levels was decreased by 30.8 % and 29.0 % after the treatment with 300 and 600 mg/kg FLL extract, respectively, indicating alleviated oxidative stress. Conclusion : The results show that aqueous FLL extract has the potential to alleviate T2D, resulting in reduced FI and FBG, and increased BW. The anti-diabetic activity of FLL extract on T2D may be relevant to reduced oxidative stress burden. Keywords : Fructus Ligustri Lucidi, Type 2 diabetes, Anti-oxidant activity, Glucose tolerance, Insulin tolerance, Anxiety-like behaviour

The Hepatoprotective Effect of Jaboticaba Peel Powder in a Rat Model of Type 2 Diabetes Mellitus Involves the Modulation of Thiol/Disulfide Redox State through the Upregulation of Glutathione Synthesis.

Jaboticaba peel powder (JPP) is rich in bioactive compounds, mainly soluble and insoluble polyphenols with great antioxidant properties. The aim of this study is to evaluate the effects of JPP supplementation on the oxidative stress and hepatic damage in a rat model of type 2 diabetes mellitus (T2DM). Diabetic rats received vehicle or JPP at 2.7 (JPP-I), 5.4 (JPP-II), or 10.8 (JPP-III) g/L in drinking water during 8 weeks. JPP-III attenuated hyperglycaemia and dyslipidemia increased by 86% the liver content of nonprotein thiol groups and by 90% the GSH/GSSG ratio by activating glutathione synthesis. Accordingly, JPP supplementation prevented the loss of activity of the sulfhydryl-dependent enzyme δ-aminolaevulinic acid dehydratase and attenuated hepatic injury assessed by the reduction of serum aspartate aminotransferase activity and liver hypertrophy. Our results support that JPP supplementation to T2DM rats decreases hepatic damage most likely by increasing glutathione synthesis and modulating the thiol/disulfide redox balance.

Morphological, Stability, and Hypoglycemic Effects of New Gliclazide-Bile Acid Microcapsules for Type 1 Diabetes Treatment: the Microencapsulation of Anti-diabetics Using a Microcapsule-Stabilizing Bile Acid

When we administered orally a mixture of the anti-diabetic drug, gliclazide (G) and a primary bile acid, they exerted a hypoglycemic effect in a rat model of type 1 diabetes (T1D), but stability of mixture was limited. We aimed to develop and characterize microcapsules incorporating G with a microcapsule-stabilizing bile acid, ursodeoxycholic acid (UDCA). Sodium alginate (SA)-based microcapsules were prepared with either G or G with UDCA and analyzed in terms of morphological, physico-chemical, and electro-chemical characteristics at different pH and temperatures. The microcapsules' effects on viability on muscle cell line (C2C12) and on diabetic rats' blood glucose levels and inflammatory profiles were also examined. Bile acid-based microcapsules maintained their morphology, showed good stability, and compatibility profiles, and the incorporation of UDCA resulted in less G content per microcapsule (p < 0.01) and production of stronger microcapsules that were more resistant to mechanical pressure (p < 0.01). G-UDCA-SA microcapsules enhanced muscle cell viability at higher glucose concentrations compared with control (G-SA and UDCA-SA), and they had strong anti-inflammatory effects on diabetic rats. In addition, the incorporation of UDCA into G microcapsules enhanced the physical characteristics of the microcapsules and optimized G delivery after oral administration.

Islet transplantation improved penile tissue fibrosis in a rat model of type 1 diabetes

BackgroundGlycaemic control is one of the most effective strategies for the treatment of diabetes-related erectile dysfunction (DMED). Compared to conventional anti-diabetic drugs and insulin, islet transplantation is more effective in the treatment of diabetic complications. The aim of this study was to investigate the efficacy of islet transplantation for reversing advanced-stage DMED in rats and to observe its influence on corpus cavernosum fibrosis.MethodsWistar rats were intraperitoneally injected with streptozotocin to establish a diabetes model. After 12 weeks, the rats were divided into 4 groups: diabetic, insulin, islet transplantation, and normal control. Following supplementation, the changes in blood glucose and weight were determined sequentially. Penile erectile function was evaluated by apomorphine experiments in the fourth week, and the penile corpus cavernosum was also collected for assessment by Masson staining, immunohistochemistry and Western blot to observe the spongy tissue and the related cellular changes at the molecular level.ResultsIslet transplantation significantly ameliorated penile erectile function in advanced-stage diabetic rats. The ratio of corpus cavernosum smooth muscle cells to fibroblasts and the expression level of α-SMA in the islet transplantation group were significantly higher than those in the diabetic and insulin groups. In addition, the expression levels of TGF-β1, p-Samd2, and connective tissue growth factor (CTGF) in the islet transplantation and insulin groups were much lower than those in the diabetic group, while those in the islet transplantation group were significantly lower than those in the insulin group.ConclusionsOur findings strongly suggest that islet transplantation can promote the regeneration of smooth muscle cells and ameliorate corpus cavernosum fibrosis to restore its normal structure in advanced-stage diabetic rats. The possible mechanism of ameliorating corpus cavernosum fibrosis by islet transplantation may be associated with improvement of the hyperglycaemic status in diabetic rats, thereby inhibiting the TGF-β1/Samd2/CTGF pathway.

Simvastatin attenuates the aberrant expression of angiogenic factors induced by glucose variability

AimOver the last few years, studies have indicated that fluctuant hyperglycemia is very likely to increase the risk of cardiovascular complications of diabetes. Statins are widely used in diabetes for the prevention of cardiovascular complications, but it is still not clear whether simvastatin could also prevent glycaemic variability – induced aberrant angiogenesis which plays a significant role in the development of atherosclerosis. MethodsWistar rats were divided into four groups: (1) simvastatin-treated (20 mg/kg for 8 consecutive weeks) type 2 diabetes rat model with daily glucose excursions, (2) placebo-treated type 2 diabetes rat model with daily glucose excursions, (3) placebo-treated stable well-controlled type 2 diabetes rat model and (4) placebo-treated non-diabetic rats. Daily glucose fluctuations and several angiogenic factors: cVEGF, mRNA VEGF, VEGF-R1, VEGF-R2, TGF-beta expression, circulating endothelial and progenitor endothelial cells were measured in all groups. ResultsSimvastatin decreased several factors enhanced by glucose excursions: circulating VEGF, mRNA TGF-beta expression in the myocardium and mRNA VEGFR-2 expression in the aorta. Simvastatin increased some factors attenuated by glucose fluctuations: mRNA VEGF expression and mRNA VEGFR-1 expression in the myocardium and in the aorta. In the simvastatin-treated group with glycaemic variability, the percentage of circulating endothelial cells was lower and the percentage of progenitor endothelial cells in peripheral blood was higher than in the placebo-treated rats with glucose-fluctuations. ConclusionsSimvastatin used in the rat model of type 2 diabetes with glucose variability reduces glucose variability and limits glucose fluctuations-induced changes in the expression of angiogenic factors in the cardiovascular system.

A novel dual PPAR-γ agonist/sEH inhibitor treats diabetic complications in a rat model of type 2 diabetes.

The metabolic syndrome is a cluster of risk correlates that can progress to type 2 diabetes. The present study aims to evaluate a novel molecule with a dual action against the metabolic syndrome and type 2 diabetes. We developed and tested a novel dual modulator, RB394, which acts as a soluble epoxide hydrolase (sEH) inhibitor and a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist in rat models of the metabolic syndrome-the obese spontaneously hypertensive (SHROB) rat and the obese diabetic Zucker fatty/spontaneously hypertensive heart failure F1 hybrid (ZSF1) rat. In SHROB rats we studied the ability of RB394 to prevent metabolic syndrome phenotypes, while in ZSF1 obese diabetic rats we compared RB394 with the ACE inhibitor enalapril in the treatment of type 2 diabetes and associated comorbid conditions. RB394 (10mg/kg daily) and enalapril (10mg/kg daily) were administered orally for 8weeks. RB394 blunted the development of hypertension, insulin resistance, hyperlipidaemia and kidney injury in SHROB rats and reduced fasting blood glucose and HbA1c, improved glucose tolerance, reduced blood pressure and improved lipid profiles in obese ZSF1 rats. A reduction in liver fibrosis and hepatosteatosis was evident in RB394-treated obese ZSF1 rats. Unlike RB394, enalapril did not demonstrate any positive effects in relation to diabetes, hyperlipidaemia or liver dysfunction in obese ZSF1 rats. RB394 ameliorated diabetic nephropathy by reducing renal interstitial fibrosis and renal tubular and glomerular injury in obese diabetic ZSF1 rats. Intriguingly, enalapril demonstrated a weaker action against diabetic nephropathy in obese ZSF1 rats. These findings demonstrate that a novel sHE inhibitor/PPAR-γ agonist molecule targets multiple risk factors of the metabolic syndrome and is a glucose-lowering agent with a strong ability to treat diabetic complications.

276 Adipose-derived stem cell-derived exosomes ameliorate erectile dysfunction in a rat model of type 2 diabetes

The efficacy of adipose-derived stem cells (ADSCs) in alleviating erectile dysfunction (ED) of diabetic rats has been demonstrated mainly through a paracrine effect. This study aimed to investigate the effect of ADSC-derived Exosomes (EXOs) on erectile function in a type 2 diabetic ED rat model. EXOs were isolated from the supernatants of cultured ADSCs by ultracentrifugation. In total, 24 type 2 diabetic rats were randomly assigned to three groups and were treated with an intracavernous injection of ADSC-derived EXOs, ADSCs, or phosphate buffered saline. Another eight age-matched rats underwent sham operation and composed the normal control group. Intracavernous pressure and mean arterial pressure testing and histologic and western blot analyses were performed 4 weeks after the intracavernous injection. ADSC-derived EXOs and ADSCs administered led to an increase in the ratio of intracavernous pressure to mean arterial pressure compared with that for phosphate buffered saline treatment. Histologic and western blot analyses demonstrated an increased ratio of smooth muscle to collagen, increased expression of an endothelial marker (CD31), a smooth muscle marker (a-smooth muscle actin), and antiapoptotic protein Bcl-2 and decreased the expression of the apoptotic protein cleaved caspase-3 and apoptosis of endothelial and smooth muscle cells in the corpus cavernosum tissue after EXO or ADSC injection compared with values for the phosphate buffered saline treatment.

Effect of Sacubitril/Valsartan vs. Valsartan on Vascular and Neural Complications in Type 2 Diabetic Rats

Previously we had shown that a vasopeptidase inhibitor, combination drug containing angiotensin converting enzyme and neprilysin inhibitors, was an effective treatment for diabetes vascular and neural complications. However, once in clinical trials, side effects prevented further development of this class of drugs. This lead to development of sacubitril/valsartan, combination drug similar to vasopeptidase inhibitors containing angiotensin II receptor blocker and neprilysin inhibitor that we hypothesized would be also an effective treatment for diabetic peripheral neuropathy. Using a rat model of type 2 diabetes, early and late intervention protocols, 4 and 12 weeks post hyperglycemia, respectively, rats were treated daily by gavage with valsartan or sacubitril/valsartan for 12 weeks followed by an extensive evaluation of vascular and neural endpoints. The results demonstrated that efficacy of sacubitril/valsartan in improving vascular and neural function was superior to valsartan alone. In the late intervention protocol, treatment of the diabetic rats was initiated well after the appearance of vascular and neural complications. Sacubitril/valsartan treatment was found to not only slow progression of vascular and neural deficits but also stimulate restoration of vascular reactivity, motor and sensory nerve conduction velocities and sensitivity/regeneration of sensory nerves of the skin and cornea. These studies suggest that sacubitril/valsartan may be an effective treatment for diabetic peripheral neuropathy and since it already has FDA approval for treatment of heart failure advancing this drug to clinical trials could proceed quickly. Disclosure M.A. Yorek: None.

Food restriction promotes damage reduction in rat models of type 2 diabetes mellitus.

There are several animal models of type 2 diabetes mellitus induction but the comparison between models is scarce. Food restriction generates benefits, such as reducing oxidative stress, but there are few studies on its effects on diabetes. The objective of this study is to evaluate the differences in physiological and biochemical parameters between diabetes models and their responses to food restriction. For this, 30 male Wistar rats were distributed in 3 groups (n = 10/group): control (C); diabetes with streptozotocin and cafeteria-style diet (DE); and diabetes with streptozotocin and nicotinamide (DN), all treated for two months (pre-food restriction period). Then, the 3 groups were subdivided into 6, generating the groups CC (control), CCR (control+food restriction), DEC (diabetic+standard diet), DER (diabetic+food restriction), DNC (diabetic+standard diet) and DNR (diabetic+food restriction), treated for an additional two months (food restriction period). The food restriction (FR) used was 50% of the average daily dietary intake of group C. Throughout the treatment, physiological and biochemical parameters were evaluated. At the end of the treatment, serum biochemical parameters, oxidative stress and insulin were evaluated. Both diabetic models produced hyperglycemia, polyphagia, polydipsia, insulin resistance, high fructosamine, hepatic damage and reduced insulin, although only DE presented human diabetes-like alterations, such as dyslipidemia and neuropathy symptoms. Both DEC and DNC diabetic groups presented higher levels of protein carbonyl groups associated to lower antioxidant capacity in the plasma. FR promoted improvement of glycemia in DNR, lipid profile in DER, and insulin resistance and hepatic damage in both diabetes models. FR also reduced the protein carbonyl groups of both DER and DNR diabetic groups, but the antioxidant capacity was improved only in the plasma of DER group. It is concluded that FR is beneficial for diabetes but should be used in conjunction with other therapies.

The possible antidiabetic effects of vitamin D receptors agonist in rat model of type 2 diabetes.

Vitamin D3 deficiency was found to be tightly linked to many health problems including metabolic syndrome, cancer, cardiovascular diseases, and type 2 diabetes mellitus. In our study, we tested the possible antidiabetic effects of one of vitamin D3 analogs, alfacalcidol, solely or in a combination with metformin on type 2 diabetic rats. Type 2 diabetic model rats were induced by feeding high-fat diet for 4weeks followed by intraperitoneal injection of streptozotocin. In addition to the control group, the diabetic rats were divided into four groups: untreated, metformin-treated, alfacalcidol-treated, and combination-treated group (metformin + alfacalcidol) for 4weeks. The level of fasting blood glucose, fasting serum insulin, homeostatic model of insulin resistance, serum lipid profile, liver enzymes, calcium, phosphorus, and 25-hydroxyvitamin D3 were also determined. Besides, sterol regulatory element binding protein-1c (SREBP-1c) and vitamin D receptors (VDR) gene expression at mRNA and protein levels were evaluated. The level of significance was fixed at P ≤ 0.05 for all statistical tests. Alfacalcidol, solely or combined with metformin, significantly ameliorated glucose homeostasis and lipid profile parameters (P < 0.001) with a neutral effect on calcium and phosphorus levels. Significant downregulation of mRNA expression of SREBP-1c in the liver, white as well as brown adipose tissues (P < 0.001) and different patterns of mRNA expression of VDR gene in pancreas and white adipose tissue were observed in rats treated with alfacalcidol solely or in combination with metformin. Vitamin D3 analogs can modulate glucose parameters and lipid metabolism in a diabetic rat model and it provides additional protective effects when combined with metformin.

Empagliflozin normalizes the size and number of mitochondria and prevents reduction in mitochondrial size after myocardial infarction in diabetic hearts.

To explore mechanisms by which SGLT2 inhibitors protect diabetic hearts from heart failure, we examined the effect of empagliflozin (Empa) on the ultrastructure of cardiomyocytes in the noninfarcted region of the diabetic heart after myocardial infarction (MI). OLETF, a rat model of type 2 diabetes, and its nondiabetic control, LETO, received a sham operation or left coronary artery ligation 12 h before tissue sampling. Tissues were sampled from the posterior ventricle (i.e., the remote noninfarcted region in rats with MI). The number of mitochondria was larger and small mitochondria were more prevalent in OLETF than in LETO. Fis1 expression level was higher in OLETF than in LETO, while phospho‐Ser637‐Drp1, total Drp1, Mfn1/2, and OPA1 levels were comparable. MI further reduced the size of mitochondria with increased Drp1‐Ser616 phosphorylation in OLETF. The number of autophagic vacuoles was unchanged after MI in LETO but was decreased in OLETF. Lipid droplets in cardiomyocytes and tissue triglycerides were increased in OLETF. Empa administration (10 mg/kg per day) reduced blood glucose and triglycerides and paradoxically increased lipid droplets in cardiomyocytes in OLETF. Empa suppressed Fis1 upregulation, increased Bnip3 expression, and prevented reduction in both mitochondrial size and autophagic vacuole number after MI in OLETF. Together with the results of our parallel study showing upregulation of SOD2 and catalase by Empa, the results indicate that Empa normalizes the size and number of mitochondria in diabetic hearts and that diabetes‐induced excessive reduction in mitochondrial size after MI was prevented by Empa via suppression of ROS and restoration of autophagy.

WITHDRAWN: The ameliorative effect of p-coumaric acid and gallic acid on oxidative stress and hematological abnormalities in a rat model of type 2 diabetes

WITHDRAWN: The ameliorative effect of p-coumaric acid and gallic acid on oxidative stress and hematological abnormalities in a rat model of type 2 diabetes

Transcriptome analysis of dorsal root ganglia's diabetic neuropathy reveals mechanisms involved in pain and regeneration

Peripheral diabetic neuropathy (DN) manifests in nearly 60% of diabetic patients, being pain its most debilitating symptom. Although electrophysiological and morphological aspects are well described, little is known about its development and progression, undermining effective therapies. Hyperglycemia and insulin signaling impairment are considered the triggering events of oxidative stress observed in the dying nerves, however there are still many gaps in the knowledge of intracellular plastic changes it generates. AimsIn this study we aimed to evaluate the early transcriptome changes in DN when the first symptoms of the disease start to appear. Main methodsNext-Generation Sequencing of messenger RNA (RNA-Seq) of L4 and L5 dorsal root ganglia (DRG) four weeks post-diabetes induction in a rat model for type 1 diabetes. Key findingsRNA sequencing found 66 transcripts differentially expressed between diabetic and control groups, related mainly to the following biological processes: inflammation, hyperalgesia/analgesia, cell growth and cell survival. Given their roles, the differentially expressed genes suggest an attempt to switch to a survival/regenerative program. SignificanceOur results show that changes in the transcriptome profile start to appear early in the course of DN and might be related to secure cell homeostasis. Hence, the present data may indicate how DRG cells are responding to hyperglycemia in its early stages and which mechanisms first fail to respond, further leading to cell damage and cell death. Early screening of cell alterations in DN might lead to more concrete targets for pharmaceutical interventions, which could more efficiently delay cell damage.

P-386 - Contribution of perivascular adipose tissue to vascular dysfunction in type 2 diabetes

Perivascular adipose tissue (PVAT) surrounds most large blood vessels and plays an important role in vascular homeostasis. The present study was conducted to investigate the contribution of PVATto vascular dysfunction in a rat model of type 2 diabetes (GK) fed with a high-fat diet (HFD). Aortic vascular reactivity was performed in GK, GK fed with HFD and compared with Wistar rats in the absence (PVAT−) or in the presence (PVAT+) of thoracic PVAT. We also measured vascular oxidative stress Endothelium-dependent relaxation to acetylcholine, assessed by wire myography, was impaired in GK and GKHFD rats, not affected by NG-nitro-L-arginine methyl ester, inhibitor of endothelial nitric oxide (NO) synthase, and improved by the antioxidant tempol, suggesting reduced NO bioavailability and increased oxidative stress. Furthermore, vascular superoxide and peroxynitrite production was increased in the vascular wall of diabetic rats. The presence of PVAThad an anti-contractile effect in response to phenylephrine in Wistar rats. In GK rats, the anti-contractile effects of PVAT were lost. Our data suggest that this rat model of type 2 diabetes is associated with perivascular adipose dysfunction, oxidative stress and endothelial dysfunction.

Effects of Apelin-13 on expression levels of glucose and lipid metabolism-related genes in the liver and skeletal muscle of diabetic rats

Objective To investigate the effects of exogenous Apelin-13 on the expression of glucose and fatty acid metabolism-related genes in the liver and skeletal muscle of diabetic rats. Methods Forty male Wister rats were randomly divided into a control group (n=8) and an experimental group (n=32). In the experimental group, a rat model of type 2 diabetes mellitus was established by a high-glucose and high-fat diet and intraperitoneal injection of streptozotocin (STZ). The diabetic rats were randomized into a diabetic model group and an Apelin-13 treatment group with 14 rats in each group.Rats in the Apelin-13 treatment group were intraperitoneally injected with 0.1 μmol·kg·d-1 Apelin-13 for 10 weeks, while the control group and the diabetic model group were injected with an equal volume of 0.9% NaCl solution for 10 weeks.At the end of the 10 week treatment, fasting blood glucose values in each group were measured.Levels of mRNA expression of glucose-6-phosphate (G-6-P), phosphoenolpyruvate carboxykinase (PEPCK), peroxisome proliferator-activated receptor alpha (PPAR-α), acy1-CoA synthetase long-chain family member1 (ACSL1), and carnitine palmitoyltransferase1 (CPT1) in the liver and levels of mRNA expression of PPAR-α and glucose transporter type 4 (GLUT4) in skeletal muscle were detected by real-time fluorescence quantitative polymerase chain reaction (PCR). Results Levels of mRNA expression of liver PPAR-α, liver ACSL1, liver CPT1, and GLUT4 in skeletal muscle were lower in the diabetic model group (0.309±0.073, 0.508±0.056, 0.389±0.118 and 0.289±0.066, respectively) than in the control group (0.971±0.028, 0.990±0.015, 0.987±0.015 and 0.994±0.009, respectively) (all P 0.05). Conclusions Apelin-13 increases the expression of the PPAR, ACSL1, and CPT1 genes in the liver and, to a certain extent, improves fatty acid oxidation metabolism in the liver in type 2 diabetic rats.It also increases the expression of the G-6-P and PEPCK genes, promotes gluconeogenesis in the liver, and may be related to the development of type 2 diabetes.In skeletal muscle, Apelin-13 increases GLUT4 gene expression, moderately improves skeletal muscle metabolism and may play a role in the regulation of oxidative stress. Key words: Diabetes mellitus; Carbohydrate metabolism; Lipid metabolism; Apelin-13

A low-protein diet exerts a beneficial effect on diabetic status and prevents diabetic nephropathy in Wistar fatty rats, an animal model of type 2 diabetes and obesity

BackgroundThe objective of this study is to investigate the effects of a low-protein diet (LPD) starting from a young age on diabetic status and renal injury in a rat model of type 2 diabetes and obesity.MethodsDiabetic male Wistar fatty (fa/fa) rats (WFRs) were fed a standard diet (23.84% protein) or an LPD (5.77% protein) for 24 weeks beginning at 6 weeks of age. We investigated the effects of the LPD on total body weight (BW); fat weight (FW); lower-limb muscle weight (MW); several measures of diabetic status, including fasting/random glucose levels, HOMA-IR and the IPITT; and renal injuries, including renal hypertrophy, albuminuria and histological changes. Additionally, autophagy and activation of mTORC1 were evaluated in the diabetic renal cortex. Furthermore, plasma FGF21 and high-molecular-weight (HMW) adiponectin levels, as well as UCP1 expression levels in brown adipose tissue (BAT), were evaluated.ResultsIncreases in BW and FW in WFRs were significantly reduced by the LPD, and the LPD resulted in a significant reduction of lower-limb MW in WFRs. The LPD suppressed the elevation of glucose levels in WFRs through improvement of insulin resistance. The LPD also elevated the plasma FGF21 and HMW adiponectin of WFRs, as well as UCP1 expression in the BAT of the animals. Renal hypertrophy, albuminuria, renal histological changes, and increased expression of p62 and phospho-S6 ribosomal protein (p-S6RP) were observed in WFRs compared with the values from WLRs. The LPD clearly prevented the diabetic kidneys from sustaining any damage.ConclusionsThe LPD prevented the progression of diabetic status; this effect may have been associated with the reduction of FW and the elevation of plasma FGF21 and HMW adiponectin, as well as UCP1 expression in BAT, resulting in suppression of diabetic nephropathy. However, MW was decreased in rats by the consumption of an LPD from a young age; therefore, further research is needed to resolve the nutritional issue of LPD on decreasing in MW.

Activation of spinal dorsal horn P2Y13 receptors can promote the expression of IL-1β and IL-6 in rats with diabetic neuropathic pain.

ObjectiveThe dorsal horn P2Y13 receptor is involved in the development of pain behavior induced by peripheral nerve injury. It is unclear whether the expression of proinflammatory cytokines interleukin (IL)-1β and IL-6 at the spinal dorsal horn are influenced after the activation of P2Y13 receptor in rats with diabetic neuropathic pain (DNP).MethodsA rat model of type 1 DNP was induced by intraperitoneal injection of streptozotocin (STZ). We examined the expression of P2Y13 receptor, Iba-1, IL-1β, IL-6, JAK2, STAT3, pTyr1336, and pTyr1472 NR2B in rat spinal dorsal horn.ResultsCompared with normal rats, STZ-diabetic rats displayed obvious mechanical allodynia and the increased expression of P2Y13 receptor, Iba-1, IL-1β, and IL-6 in the dorsal spinal cord that was continued for 6 weeks in DNP rats. The data obtained indicated that, in DNP rats, administration of MRS2211 significantly attenuated mechanical allodynia. Compared with DNP rats, after MRS2211 treatment, expression of the P2Y13 receptor, Iba-1, IL-1β, and IL-6 were reduced 4 weeks after the STZ injection. However, MRS2211 treatment did not attenuate the expression of the P2Y13 receptor, Iba-1, IL-1β, and IL-6 at 6 weeks after the STZ injection. MRS2211 suppressed JAK2 and STAT3 expression in the early stage, but not in the later stage. Moreover, pTyr1336 NR2B was significantly decreased, whereas pTyr1472 NR2B was unaffected in the dorsal spinal cord of MRS2211-treated DNP rats.ConclusionIntrathecal MRS2211 produces an anti-nociceptive effect in early-stage DNP. A possible mechanism involved in MRS2211-induced analgesia is that blocking the P2Y13 receptor downregulates levels of IL-1β and IL-6, which subsequently inhibit the activation of the JAK2/STAT3 signaling pathway. Furthermore, blocking the activation of the P2Y13 receptor can decrease NR2B-containing NMDAR phosphorylation in dorsal spinal cord neurons, thereby attenuating central sensitization in STZ-induced DNP rats.