Dysfunction In Diabetic Rats Research Articles

Effect of capsaicin on cardiac dysfunction in diabetic rats: an in vitro experiment

Objective To evaluate the effect of capsaicin on cardiac dysfunction in diabetic rats using an in vitro experiment. Methods Healthy male Sprague-Dawley rats, weighing 240-260 g, in which type 1 diabetes mellitus was induced by intraperitoneal streptozotocin 50 mg/kg, were studied.Eighteen diabetic rats were selected at 8 weeks after successful establishment of the model and divided into 3 groups (n=6 each) using a random number table: diabetes mellitus group (DM group), capsaicin group (CAP group) and capsaicin plus capsazepine group (CPZ group). Another 8 rats with normal blood glucose served as control group (C group). Rat hearts were quickly removed under deep anesthesia and retrogradely perfused with an oxygen-saturated K-H solution (at 37 ℃) using a Langendorff apparatus.Cardiac function was maintained stable for 10 min.The hearts were continuously perfused with K-H solution for 30 min in C and DM groups.The hearts were perfused with K-H solution for 20 min, and capsaicin (1.4×10-9 g/L) was then infused for 10 min via the branch of aortic cannula using micro pump in CAP group.The hearts were perfused with K-H solution for 10 min, and capsaicin receptor-transient receptor potential vanilloid type 1 antagonist capsazepine (1.4×10-7 g/L) was then infused for 10 min followed by infusion of capsaicin (1.4×10-9 g/L) at 0.5 ml/min for 10 min via the branch of aortic cannula using a micro-pump in CPZ group.Left ventricular systolic pressure (LVSP), left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), heart rate, the maximum rate of increase or decrease in left ventricular pressure (±dp/dtmax) were recorded at 10, 20 and 30 min of continuous infusion (T1-3). Results There was no significant difference in LVEDP and ±dp/dtmax at each time point among the four groups (P>0.05). Compared with C group, LVSP and LVDP were significantly decreased at T1-3 in DM and CPZ groups and at T1-2 in CAP group, and heart rate was significantly decreased at T1-3 in DM, CPZ and CAP groups (P 0.05). LVSP and LVDP were significantly lower at T3 in CPZ group than in CAP group (P<0.05). Conclusion Capsaicin can mitigate cardiac dysfunction in diabetic rats, and the mechanism is related to activating transient receptor potential vanilloid type 1. Key words: Capsaicin; Diabetes mellitus; Heart function tests

Grape seed proanthocyanidin extract alleviates urethral dysfunction in diabetic rats through modulating the NO-cGMP pathway.

Oxidative stress is closely associated with the onset of diabetes mellitus (DM). Diabetic urethropathy is one of the most common complications of DM, but few studies have been conducted to investigate the role of oxidative stress in diabetic urethropathy. Grape seed proanthocyanidin extract (GSPE) has been previously reported to reduce oxidative injury. The present study aimed to investigate the role of oxidative stress and the protective effects of GSPE on urethral dysfunction using a streptozotocin-induced DM rat model. Female Wistar rats were divided into a control group (n=36), a DM group (n=36) and a DM + GSPE group (n=36). Urodynamic testing was performed using a PowerLab data acquisition device. The expression of neuronal nitric oxide synthase (nNOS), 3-nitrotyrosine and nuclear factor erythroid 2-related factor 2 (Nrf2) was determined using western blot analysis. The expression of 3-nitrotyrosine was also determined using immunohistochemistry. Nitric oxide (NO), cyclic guanosine monophosphate (cGMP), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) were measured using commercial ELISA kits. A significant increase was observed in the intravesical pressure thresholds for inducing urethral relaxation and the urethral perfusion pressure nadir in DM rats compared with the control group. GSPE was observed to reverse the increase of these parameters compared with the DM group. In addition, GSPE could reverse the downregulation of nNOS, NO and cGMP expression, and the decreased activities of antioxidant enzymes (SOD and GSH-Px). GSPE reversed the upregulation of 3-nitrotyrosine and MDA in DM rats. GSPE also activated Nrf2, which is a key antioxidative transcription factor. The findings of the present study demonstrated that GSPE protects urethra function in DM rats through modulating the NO-cGMP signaling pathway. The protective roles of GSPE may be associated with activation of the Nrf2 defense pathway.

Effect of incubation with L-citrulline ex vivo on relaxation dysfunction of corpus cavernosum from type 2 diabetic rats

Objective To explore the role of the changes in endogenous L-citrulline levels and arginases expression in erectile dysfunction of diabetic rats, and investigate the effect of L-citrulline incubation ex vivo on the erectile dysfunction. Methods Type 2 diabetic rats were induced by high fat diet plus a single intraperitoneal injection of small dose streptozotocin (30 mg/kg), followed by high fat diet for 8 weeks. The erectile function of rats was reflected by the relaxation response to acetylcholine (ACh) of corpus cavernosum detected by isometric tension measurement. Levels of endogenous nitric oxide inhibitor asymmetric dimethylarginine (ADMA) and cyclic guanosine monophosphate (cGMP) were measured by enzyme-linked immunosorbent assay (ELISA). The content of L-citrulline, nitric oxide (NO) and the activity of nitric oxide synthase (NOS) were determined with colorimetric method. Western blotting was applied to detect the protein expression of NOS, arginases and phosphodiesterase 5 (PED5). Results The relaxation response to ACh of corpus cavernosum from diabetic rats was significantly lower than that of control rats (P<0.01), indicating the erectile dysfunction of diabetic rats. This erectile dysfunction was companied by the decreases of L-citrulline levels in serum and corpus cavernosum as well as up-regulation of arginaseⅠ& Ⅱ expression in the corpus cavernosum of diabetic rats. Incubation with L-citrulline (3 mmol/L) for 45 min ex vivo im-proved the relaxation function of corpus cavernosum from diabetic rats (P<0.05), while incubation with PED5 inhibitor silaenafil (3 μmol/L) had no significant effect. Furthermore, the ADMA level was increased, while the NOS activity, cGMP and NO contents were decreased in corpus cavernosum of diabetic rats compared to control rats. Down-regulation of endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS) protein expression as well as up-regulation of inducible nitric oxide synthase (iNOS) and PDE5 protein expression were also observed in the corpus cavernosum of diabetic rats. Conclusions The decreased endogenous L-citrulline levels and upregulated arginases expression was closely related to erectile dysfunction of diabetic rats, and the mechanism is associated to the up-regulation of arginase activity and decrease of NO synthesis in corpus cavernosum. L-citrulline incubation ex vivo exerted therapeutic effect on the relaxation dysfunction of corpus cavernosum from diabetic rats. Key words: L-citrulline; Diabetes mellitus; Erectile dysfunction; Arginase; Nitric oxide

Chinese Olive (Canarium album L.) Fruit Extract Attenuates Metabolic Dysfunction in Diabetic Rats.

Hyperglycemia and dysregulation of lipid metabolism play a crucial role in metabolic dysfunction. The aims of present study were to evaluate the ameliorative effect of the ethyl acetate fraction of Chinese olive fruit extract (CO-EtOAc) on high-fat diet (HFD) and streptozotocin (STZ)-induced diabetic rats. CO-EtOAc, rich in gallic acid and ellagic acid, could markedly decreased the body weight and epididymal adipose mass. In addition, CO-EtOAc increased serum HDL-C levels, hepatic GSH levels, and antioxidant enzyme activities; lowered blood glucose, serum levels of total cholesterol (TC), triglycerides (TG), bile acid, and tumor necrosis factor alpha (TNFα); and reduced TC and TG in liver. We further demonstrated that CO-EtOAc mildly suppressed hepatic levels of phosphorylated IRS-1, TNF-α, and IL-6, but enhanced Akt phosphorylation. The possible mechanisms of cholesterol metabolism were assessed by determining the expression of genes involved in cholesterol transportation, biosynthesis, and degradation. It was found that CO-EtOAc not only inhibited mRNA levels of SREBP-2, HMG-CoAR, SR-B1, and CYP7A1 but also increased the expression of genes, such as ABCA1 and LDLR that governed cholesterol efflux and cholesterol uptake. Moreover, the protein expressions of ABCA1 and LDLR were also significantly increased in the liver of rats supplemented with CO-EtOAc. We suggest that Chinese olive fruit may ameliorate metabolic dysfunction in diabetic rats under HFD challenge.

Oleanolic acid alleviates diabetic rat carotid artery injury through the inhibition of NLRP3 inflammasome signaling pathways.

The overexpression of inflammasome components is correlated with diabetes‑associated complications. Oleanolic acid is a triterpenoid compound which is important in arterial injury. The present study evaluated whether oleanolic acid improved diabetic rat carotid artery injury through the inhibition of nucleotide‑binding domain, leucine‑rich‑containing family, pyrin domain‑containing‑3 (NLRP3) inflammasomes signaling pathways. A diabetic rat model was induced using streptozotocin (60mg/kg) and underwent carotid artery injury. Morphometric analysis was performed using hematoxylin and eosin staining. The mRNA and protein levels were assayed by reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. It was found that oleanolic acid (100mg/kg/day) improved body weight, glucose metabolic disorders, neointimal hyperplasia and endothelial dysfunction in diabetic rats with carotid artery injury. In addition, oleanolic acid administration significantly downregulated the mRNA and protein expression levels of endothelin1 in diabetic rats. Oleanolic acid decreased the intimal area and the ratio of neointima to media in diabetic rats. Serum levels of tumor necrosis factor‑α, interleukin(IL)‑1β, IL‑6 and IL‑18 in the oleanolic acid‑treated diabetic rats were downregulated. Consistent with the serum results, it was demonstrated that oleanolic acid administration caused a significant decrease in the levels of NLRP3, caspase‑1 and IL‑1β in the carotid arteries of diabetic rats. Taken together, these observations suggested that oleanolic acid attenuated carotid artery injury in diabetic rats and the underlying mechanism was mediated, at least partially, through the suppression of NLRP3 inflammasome signaling pathways.

Administration of Selenium Decreases Lipid Peroxidation and Increases Vascular Endothelial Growth Factor in Streptozotocin Induced Diabetes Mellitus.

The imbalance in oxidant/antioxidant status plays a pivotal role in diabetes mellitus (DM). Selenium is a integral component of the antioxidant enzyme glutathione peroxidase. Se treatment induces angiogenesis and improves endothelial function through increased expression of vascular endothelial growth factor (VEGF). The aim of this study is to investigate the effect of selenium on oxidative stress, VEGF, and endothelin 1 (ET1) in a DM rat model. We performed an experimental animal study with 64 adult male Wistar-Albino rats. Rats were divided into the following groups (n=8): control (C)7, C21, C+sodium selenite (Se)7, and C+Se21 (control rats), and DM7, DM21, DM+Se7, and DM+Se21 (diabetic rats). Diabetes was induced by 2-deoxy-2-(3-methyl-3-nitrosoureido)- D-glucopyranose [streptozotocin (STZ)]. Three weeks after STZ, DM+Se7 rats received intraperitoneal (i.p.) injections of 0.4 mg/kg Se for 7 days. The DM+Se21 rats received these injections for 21 days. The same dose/duration of Se was administered to the C+Se7 and C+Se21 groups. The remaining rats (C7, C21, DM7, DM21) received physiologic saline injections for 7 or 21 days. Ferric reducing antioxidant power (FRAP), malondialdehyde (MDA), advanced oxidation protein products (AOPP), and endothelial function markers (VEGF and ET1) in plasma samples were measured. Diabetic rats (DM7 and DM21) had significantly increased plasma FRAP (P=0.002, P=0.001), AOPP (P=0.024, P=0.01), MDA (P=0.004, P=0.001), and ET1 (P=0.028, P=0.003) levels compared with C7 and C21 control rats. VEGF (P=0.02, P=0.01) significantly decreased in DM7 and DM21 diabetic rats compared with their controls (C7, C21). Se administration reversed the increased MDA and decreased VEGF levels, and lowered plasma glucose levels in the DM+Se7 and DM+Se21 diabetic groups compared with diabetic rats (DM7, DM21). We observed positive correlations between FRAP-AOPP (r=0.460), FRAP-ET1 (r=0.510), AOPP-MDA (r=0.270), and AOPP-ET1 (r=0.407), and a negative correlation between MDA-VEGF (r=-0.314). We observed accentuated oxidative stress and impaired endothelial function in diabetes. Se treatment reduced lipid peroxidation and hyperglycemia. Se probably improved endothelial dysfunction in diabetic rats because of the increased VEGF levels.

Tadalafil, a phosphodiesterase type 5 inhibitor, improves bladder blood supply and restores the initial phase of lower urinary tract dysfunction in diabetic rats.

To investigate the effect of tadalafil on bladder blood flow and lower urinary tract function in a rat model of diabetes. We studied female Sprague-Dawley rats and induced diabetes in some using a single intraperitoneal injection of streptozotocin. We divided the rats into nondiabetes (ND), diabetes (D), and diabetes with tadalafil (DT) groups. The rats were raised for an additional 7 weeks after diabetes induction. The DT group received oral tadalafil (2 mg/kg/day) for 7 days before the experiments. At 7 weeks after diabetes induction, we performed cystometry, resected the bladders for immunohistochemistry (hypoxia-inducible factor-1α [HIF-1α] and 8-oxo-2'-deoxyguanosine [8-OHdG] staining), and measured bladder blood supply using a laser blood flow meter. The opening pressure, when the urethra opens and urine flow starts, was significantly lower in the DT group than in the D group (24.9 ± 5.9 vs 43.6 ± 12.3 cmH2 O). The inter-contraction interval was significantly longer in the D group than in the ND and DT groups (1566.2 ± 168.7 vs 702.9 ± 165.2 and 787.4 ± 148.8 s). Immunohistochemistry showed positive staining of the urothelial layer for both HIF-1α and 8-OHdG in the D group, but not in the ND or DT groups. Bladder blood flow was significantly lower in the D group than in the ND or DT groups. Tadalafil improves bladder blood supply and lower urinary tract function in diabetic rats. Tadalafil may be a promising drug that restores lower urinary tract dysfunction in the early phase of diabetes.

Erythropoietin Attenuates Cardiac Dysfunction in Rats by Inhibiting Endoplasmic Reticulum Stress-Induced Diabetic Cardiomyopathy.

Enhanced endoplasmic reticulum (ER) stress and down-regulated SERCA2a expression play crucial roles in diabetes. We aimed to verify whether erythropoietin (EPO) attenuates cardiac dysfunction by suppressing ER stress in diabetic rats. Forty male SD rats were randomly divided into four groups: control, EPO-treated control, vehicle-treated diabetic, and EPO-treated diabetic groups. The animals in the EPO-treated control and diabetic groups were administered recombinant human EPO (1000U/kg body weight) once per week for 12weeks. RT-PCR and Western blotting assays were performed to detect the expression of 78-kDa glucose-regulated protein precursor (GRP78) and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA2a). We cultured neonatal rat cardiomyocytes and investigated the protective effects of EPO against high glucose (HG)-induced apoptosis. Intracellular calcium levels were measured through confocal microscopy. We observed increased myocardial GRP78 expression and decreased myocardial SERCA2a expression in diabetic rats. EPO prevented the changes in GRP78, SERCA2a expression and cardiac dysfunction in diabetic rats. The levels of GRP78 protein were significantly reduced in EPO-treated diabetic rats compared with vehicle-treated diabetic rats (GRP78 protein 0.09±0.03 vs. 0.54±0.04, P<0.01). The levels of the SERCA2a proteins were significantly increased in EPO-treated diabetic rats compared with vehicle-treated diabetic rats (SERCA2a protein 0.60±0.05 vs. 0.13±0.04, P<0.01). A reduction in apoptosis was observed in the cardiomyocytes treated with 20U/mL EPO compared with the cardiomyocytes cultured under HG conditions (apoptosis rate 18.9±1.94 vs. 37.9±1.59%, P<0.01). This study demonstrates that EPO treatment improved the parameters of cardiac function following HG-induced injury by suppressing ER stress and inducing SERCA2a expression.

Atorvastatin reduces β-Adrenergic dysfunction in rats with diabetic cardiomyopathy.

BackgroundIn the diabetic heart the β-adrenergic response is altered partly by down-regulation of the β1-adrenoceptor, reducing its positive inotropic effect and up-regulation of the β3-adrenoceptor, increasing its negative inotropic effect. Statins have clinical benefits on morbidity and mortality in diabetic patients which are attributed to their “pleiotropic” effects. The objective of our study was to investigate the role of statin treatment on β-adrenergic dysfunction in diabetic rat cardiomyocytes.Methodsβ-adrenergic responses were investigated in vivo (echocardiography) and ex vivo (left ventricular papillary muscles) in healthy and streptozotocin-induced diabetic rats, who were pre-treated or not by oral atorvastatin over 15 days (50 mg.kg-1.day-1). Micro-array analysis and immunoblotting were performed in left ventricular homogenates. Data are presented as mean percentage of baseline ± SD.ResultsAtorvastatin restored the impaired positive inotropic effect of β-adrenergic stimulation in diabetic hearts compared with healthy hearts both in vivo and ex vivo but did not suppress the diastolic dysfunction of diabetes. Atorvastatin changed the RNA expression of 9 genes in the β-adrenergic pathway and corrected the protein expression of β1-adrenoceptor and β1/β3-adrenoceptor ratio, and multidrug resistance protein 4 (MRP4). Nitric oxide synthase (NOS) inhibition abolished the beneficial effects of atorvastatin on the β-adrenoceptor response.ConclusionsAtorvastatin restored the positive inotropic effect of the β-adrenoceptor stimulation in diabetic cardiomyopathy. This effect is mediated by multiple modifications in expression of proteins in the β-adrenergic signaling pathway, particularly through the NOS pathway.

Vitamin C Improves Gastroparesis in Diabetic Rats: Effects on Gastric Contractile Responses and Oxidative Stress.

Diabetic gastroparesis is a common complication of diabetes mellitus, which mainly affects women. Previous studies have demonstrated that oxidative stress is involved in its onset and development. This study evaluated the role of vitamin C on diabetes-associated gastric dysmotility. Female rats with streptozotocin-induced diabetes were treated with vehicle (water, 1mL/kg, p.o.), vitamin C (300mg/kg/day, p.o.), or insulin (6IU/day, s.c.). Gastric emptying, in vitro gastric contractility, and biochemistry parameters were analyzed at the end of the treatment (i.e. 8weeks after the diabetes induction). Vitamin C reversed the delayed gastric emptying of diabetic rats to normal levels, and avoided the changes in the contractile responses to acetylcholine (0.1nM-1µM), but not to 5-hydroxytryptamine (0.1nM-1µM), in the pylorus and fundus from diabetic rats. Moreover, the contraction evoked by KCl (40mM) in the fundus, but not in the pylorus, was intensely increased in diabetic rats treated with vitamin C. Notably, the vitamin C reestablished the reduced glutathione levels by 77% and decreased the reactive oxygen species content by 60% in the gastric tissue from diabetic rats. Despite the effects on gastric motility, vitamin C treatment did not change the fasting glycaemia or the glycated hemoglobin of diabetic rats. Unsurprisingly, insulin treatment normalized all parameters evaluated. Vitamin C exhibited a remarkable beneficial effect on gastric emptying dysfunction in diabetic rats, which was mediated by attenuation of oxidative stress and maintenance of the cholinergic contractile responses in fundus and pylorus.

Ameliorative potential of Blighia sapida K.D. Koenig bark against pancreatic β-cell dysfunction in alloxan-induced diabetic rats.

Background In West Africa, the fruit, seed, leaf and stem of Blighia sapida K.D. Koenig are commonly used as remedy against a variety of diseases, including diabetes mellitus. This study investigated the ameliorative potential of B. sapida K.D. Koenig stem bark ethanol extract against pancreatic β-cell dysfunction in diabetic rats. Methods Diabetes was induced by intraperitoneal injection of alloxan (65 mg/kg body weight) for 21 days, and orally administered with glibenclamide (5 mg/kg body weight), 50-150 mg/kg body weight of B. sapida stem bark ethanol extract once daily for 21 days. Results The blood glucose levels of rats induced with alloxan were significantly and gradually reduced (p<0.05) in B. sapida stem bark ethanol extract treated animals at the dose of 50-150 mg/kg body weight, and in glibenclamide-treated animals. The significant increase in the lipid peroxidation (malonaldehyde), homeostasis model assessment-insulin resistance scores (HOMA-IR) and decrease in serum insulin, pancreatic β-cell scores as well as antioxidant marker enzymes in untreated diabetic rats compared to normal control rats were reversed by the B. sapida stem bark ethanol extract and glibenclamide. Similarly, histopathological changes in the pancreas were also reversed by the extract and glibenclamide. However, these effects were most prominent in the animals treated with 150 mg/kg body weight of B. sapida bark. Conclusions These findings indicate that B. sapida stem bark possess anti-hyperglycemic activity and exhibits ameliorative potential in managing diabetes.

Salusin-\u03b2 contributes to oxidative stress and inflammation in diabetic cardiomyopathy

Salusin-β accelerates inflammatory responses in vascular endothelial cells, and increases oxidative stress in vascular smooth muscle cells. Plasma salusin-β levels were increased in diabetic patients. This study was designed to determine whether salusin-β is involved in the pathogenesis of diabetic cardiomyopathy (DCM), and whether knockdown of salusin-β attenuates cardiac inflammation and oxidative stress in rats with DCM. H9c2 or neonatal rat cardiomyocytes were incubated with 33.3 mM of glucose to mimic the high glucose (HG) in diabetes. Streptozotocin and high-fat diet were used to induce type 2 diabetes in rats. HG induced salusin-β expression in H9c2 cells. Salusin-β caused greater responses of oxidative stress, NFκB activation and inflammation in HG-treated H9c2 cells than these in control H9c2 cells. Diphenyleneiodonium (a NAD(P)H oxidase inhibitor) or N-acetylcysteine (an antioxidant) inhibited the salusin-β-induced NFκB activation and inflammation. Bay11-7082 (a NFκB inhibitor) attenuated salusin-β-induced inflammation but not oxidative stress. Knockdown of salusin-β prevented the HG-induced oxidative stress, NFκB activation and inflammation in neonatal rat cardiomyocytes. Silencing salusin-β with adenoviruse-mediated shRNA had no significant effects on blood glucose and insulin resistance, but attenuated ventricular dysfunction in diabetic rats. Oxidative stress, NFκB activation, inflammation, salusin-β upregulation in myocardium of diabetic rats were prevented by knockdown of salusin-β. These results indicate that salusin-β contributes to inflammation in DCM via NOX2/ROS/NFκB signaling, and that knockdown of salusin-β attenuates cardiac dysfunction, oxidative stress and inflammation in DCM.

The impact of exogenous estrogens on biochemical markers of endothelial dysfunction in diabetic rats with hypoestrogenia

It was investigated the impact of selective estrogen receptor modulator PE0607 comparing to 17β-estradiol on the biochemical markers of endothelial dysfunction in ovariectomized rats with type 2 diabetes. It was established that injection of PE0607 as well as 17β-estradiol decreases lipid peroxidation first products in serum and increases serum whole antioxidant activity and NO-synthase activity in vessels of experimental rats. These results justify the perspectives of compound PE0607 use as a potential gender-specific agent for prevention and treatment of diabetic cardiovascular disorders in women with hypoestrogenia.

385 Losartan Preserves Erectile Function by Suppression of Cavernosal Fibrosis and Corporal Veno-Occlusive Dysfunction in Diabetic Rats

385 Losartan Preserves Erectile Function by Suppression of Cavernosal Fibrosis and Corporal Veno-Occlusive Dysfunction in Diabetic Rats

Down-regulation of fibroblast growth factor 2 and its co-receptors heparan sulfate proteoglycans by resveratrol underlies the improvement of cardiac dysfunction in experimental diabetes

Cardiac remodeling in diabetes involves cardiac hypertrophy and fibrosis, and fibroblast growth factor 2 (FGF2) is an important mediator of this process. Resveratrol, a polyphenolic antioxidant, reportedly promotes the improvement of cardiac dysfunction in diabetic rats. However, little information exists linking the amelioration of the cardiac function promoted by resveratrol and the expression of FGF2 and its co-receptors, heparan sulfate proteoglycans (HSPGs: Glypican-1 and Syndecan-4), in cardiac muscle of Type 2 diabetic rats. Diabetes was induced experimentally by the injection of streptozotocin and nicotinamide, and the rats were treated with resveratrol for 6 weeks. According to our results, there is an up-regulation of the expression of genes and/or proteins of Glypican-1, Syndecan-4, FGF2, peroxisome proliferator-activated receptor gamma and AMP-activated protein kinase in diabetic rats. On the other hand, resveratrol treatment promoted the attenuation of left ventricular diastolic dysfunction and the down-regulation of the expression of all proteins under study. The trigger for the changes in gene expression and protein synthesis promoted by resveratrol was the presence of diabetes. The negative modulation conducted by resveratrol on FGF2 and HSPGs expression, which are involved in cardiac remodeling, underlies the amelioration of cardiac function.

N-acetylcysteine attenuates myocardial dysfunction and postischemic injury by restoring caveolin-3/eNOS signaling in diabetic rats.

BackgroundPatients with diabetes are prone to develop cardiac hypertrophy and more susceptible to myocardial ischemia–reperfusion (I/R) injury, which are concomitant with hyperglycemia-induced oxidative stress and impaired endothelial nitric oxide (NO) synthase (eNOS)/NO signaling. Caveolae are critical in the transduction of eNOS/NO signaling in cardiovascular system. Caveolin (Cav)-3, the cardiomyocytes-specific caveolae structural protein, is decreased in the diabetic heart in which production of reactive oxygen species are increased. We hypothesized that treatment with antioxidant N-acetylcysteine (NAC) could enhance cardiac Cav-3 expression and attenuate caveolae dysfunction and the accompanying eNOS/NO signaling abnormalities in diabetes.MethodsControl or streptozotocin-induced diabetic rats were either untreated or treated with NAC (1.5 g/kg/day, NAC) by oral gavage for 4 weeks. Rats in subgroup were randomly assigned to receive 30 min of left anterior descending artery ligation followed by 2 h of reperfusion. Isolated rat cardiomyocytes or H9C2 cells were exposed to low glucose (LG, 5.5 mmol/L) or high glucose (HG, 25 mmol/L) for 36 h before being subjected to 4 h of hypoxia followed by 4 h of reoxygenation (H/R).ResultsNAC treatment ameliorated myocardial dysfunction and cardiac hypertrophy, and attenuated myocardial I/R injury and post-ischemic cardiac dysfunction in diabetic rats. NAC attenuated the reductions of NO, Cav-3 and phosphorylated eNOS and mitigated the augmentation of O2 −, nitrotyrosine and 15-F2t-isoprostane in diabetic myocardium. Immunofluorescence analysis demonstrated the colocalization of Cav-3 and eNOS in isolated cardiomyocytes. Immunoprecipitation analysis revealed that diabetic conditions decreased the association of Cav-3 and eNOS in isolated cardiomyocytes, which was enhanced by treatment with NAC. Disruption of caveolae by methyl-β-cyclodextrin or Cav-3 siRNA transfection reduced eNOS phosphorylation. NAC treatment attenuated the reductions of Cav-3 expression and eNOS phosphorylation in HG-treated cardiomyocytes or H9C2 cells. NAC treatment attenuated HG and H/R induced cell injury, which was abolished during concomitant treatment with Cav-3 siRNA or eNOS siRNA.ConclusionsHyperglycemia-induced inhibition of eNOS activity might be consequences of caveolae dysfunction and reduced Cav-3 expression. Antioxidant NAC attenuated myocardial dysfunction and myocardial I/R injury by improving Cav-3/eNOS signaling.

Fish oil and wheat-germ oil supplementation restores ovarian function in streptozotocin-diabetic rats

Diabetes is a chronic metabolic disorder and has a profound impact on women's reproductive health. This study aimed to investigate the protective effect of a mixture of fish oil (FO) and wheat-germ oil (WGO) on ovarian dysfunction in diabetic rats. Female Albino rats were divided into control, diabetic and FO-WGO-diabetic groups. Diabetes was induced by intraperitoneal injection of 65mgkg-1 streptozotocin (STZ). Three weeks later, rats were given oral supplement of 0.4gkg-1 oil mix (1000mg FO+100mg WGO) daily for 3 weeks. Antioxidant activity was assessed by measuring malondialdehyde (MDA) and reduced glutathione (GSH) levels, the GSH:oxidised glutathione (GSSG) ratio and superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities. Ovary function was indicated by serum concentrations of FSH, oestradiol (E2), LH, anti-Müllerian hormone (AMH), ovary histopathology and follicle counts. Anti-inflammatory properties were detected by measuring nuclear factor (NF)-κB in follicular cells by immunohistochemistry. FO-WGO supplementation enhanced CAT, SOD and GPx activities and raised GSH levels and the GSH:GSSG ratio. Supplementation also increased FSH, E2, LH and AMH levels and follicle counts. Moreover, NF-kB expression and MDA were reduced. These findings indicate that FO-WGO supplementation preserved ovarian function in STZ-induced diabetic rats.

Preservation of CGRP in myocardium attenuates development of cardiac dysfunction in diabetic rats

BackgroundCalcitonin gene-related peptide (CGRP) plays an important role in cardiovascular regulation, which was found reduced in serum of diabetic patients. To test the hypothesis that lack of CGRP in myocardium is associated with diabetic cardiac dysfunction, which may be improved by preservation of CGRP in diabetic rats. Methods and resultsDiabetes was induced in male Sprague–Dawley rats by streptozotocin (50mg/kg). Two groups of the diabetic rats, one fed with standard laboratory chew and another with the laboratory food plus hot pepper (containing 0.0174% of capsaicin), to stimulate production and release of CGRP. Cardiac functions were evaluated by measurements of intraventricular pressures after 8weeks of development of diabetes. Transient receptor potential vanilloid type 1 (TRPV1), CGRP, β1-adreneregic receptor and norepinephrine were analyzed. Significantly lower levels of TRPV1 and CGRP were detected in the thoracic dorsal root ganglia (DRG) and myocardium of the diabetic animals, along with significant decline in left ventricular systolic pressure (by 24%) and heart rate (by 25%) and increase of the end-diastolic pressure (by 83%) with obvious reduction of CGRP in the DRG, by 41%, the myocardium (by 30%) and the serum (by 20%). The cardiac performance, the TRPV1 and the CGRP in the diabetic animals fed with hot pepper were well preserved. No any significant change in β1-adreneregic receptor and norepinephrine was detected. ConclusionThe findings may suggest a novel mechanism underlying diabetic cardiac dysfunctions via impairing TRPV1-CGRP pathway in myocardium. Preservation of the TRPV1-CGRP mechanism may prevent the development of cardiac dysfunction in diabetes.

Comparison of adipose tissue- and bone marrow- derived mesenchymal stem cells for alleviating doxorubicin-induced cardiac dysfunction in diabetic rats.

IntroductionDoxorubicin (DOX) is a well-known anticancer drug. However its clinical use has been limited due to cardiotoxic effects. One of the major concerns with DOX therapy is its toxicity in patients who are frail, particularly diabetics. Several studies suggest that mesenchymal stem cells (MSCs) have the potential to restore cardiac function after DOX-induced injury. However, limited data are available on the effects of MSC therapy on DOX-induced cardiac dysfunction in diabetics. Our objective was to test the efficacy of bone marrow-derived (BM-MSCs) and adipose-derived MSCs (AT-MSCs) from age-matched humans in a non-immune compromised rat model.MethodsDiabetes mellitus was induced in rats by streptozotocin injection (STZ, 65 mg/kg b.w, i.p.). Diabetic rats were treated with DOX (doxorubicin hydrochloride, 2.5 mg/kg b.w, i.p) 3 times/wk for 2 weeks (DOX group); or with DOX+ GFP labelled BM-MSCs (2x106cells, i.v.) or with DOX + GFP labelled AT-MSCs (2x106cells, i.v.). Echocardiography and Langendorff perfusion analyses were carried out to determine the heart function. Immunostaining and western blot analysis of the heart tissue was carried out for CD31 and to assess inflammation and fibrosis. Statistical analysis was carried out using SPSS and data are expressed as mean ± SD.ResultsGlucose levels in the STZ treated groups were significantly greater than control group. After 4 weeks of intravenous injection, the presence of injected MSCs in the heart was confirmed through fluorescent microscopy and real time PCR for ALU transcripts. Both BM-MSCs and AT-MSCs injection prevented DOX-induced deterioration of %FS, LVDP, dp/dt max and rate pressure product. Staining for CD31 showed a significant increase in the number of capillaries in BM-MSCs and AT-MSCs treated animals in comparison to DOX treated group. Assessment of the inflammation and fibrosis revealed a marked reduction in the DOX-induced increase in immune cell infiltration, collagen deposition and αSMA in the BM-MSCs and AT-MSCs groups.ConclusionsIn conclusion BM-MSCs and AT-MSCs were equally effective in mitigating DOX-induced cardiac damage by promoting angiogenesis, decreasing the infiltration of immune cells and collagen deposition.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-015-0142-x) contains supplementary material, which is available to authorized users.

Alteration in amyloid β42, phosphorylated tau protein, interleukin 6, and acetylcholine during diabetes-accelerated memory dysfunction in diabetic rats: correlation of amyloid β42 with changes in glucose metabolism.

BackgroundDiabetes accelerates memory dysfunction in a continuous, slowly pathological process. Studies suggest that the time course of certain biomarkers can characterize the pathological course of the disease to provide information for early intervention. Thus, there is an urgent need for validated biomarkers to characterize the cognitive impairment induced by DM. We aimed to detect changes in cerebrospinal fluid biomarkers such as amyloid β42, phosphorylated tau protein, interleukin 6, and acetylcholine in diabetic rats over time, and to analyse the relationship between diabetes and cognitive impairment.MethodsRats were injected once intraperitoneally with 1% of streptozotocin to establish a diabetic model. Index changes were investigated longitudinally and all were measured at the end of the experiment at day 75. Aβ42, P-tau, IL-6, and ACh levels in CSF, insulin levels in plasma, and Aβ42 levels in plasma and brain tissue were measured by ELISA.ResultsCompared with control, the diabetic model showed ACh in CSF to be decreased by day 15, continuing lower out to day 75. Aβ42 changes in brain and blood showed the same trends but exhibited minima at different time points: day 30 in CSF and day 15 in plasma. After the minimum, Aβ42 in cerebrospinal fluid rose and levelled off lower than in the control group, whereas Aβ42 in plasma rose and went above the controls at day 30, slowly trending upwards for the remainder of the experiment. P-tau protein in CSF in diabetic rats showed an increasing trend, becoming significantly different from the controls at day 60 and day 75. Aβ42 in CSF was strongly negatively correlated with blood glucose at day 15 and was negatively correlated with insulin in serum, particularly at day 45.ConclusionOur longitudinal research model suggest that changes in the measured biomarkers appear before learning and memory impairments do. Aβ42 and ACh in the diabetes model group clearly changed from day 0 to day 45, and then P-tau and IL-6 varied significantly from day 45 to day 75. The reduced ACh levels observed possibly correlated with the factors common to changes in Aβ42, P-tau, and IL-6.