Organic nitrates and nitrate resistance in diabetes: the role of vascular dysfunction and oxidative stress with emphasis on antioxidant properties of pentaerithrityl tetranitrate

Prescription pattern analysis of Type 2 Diabetes Mellitus: a cross-sectional study in Isfahan, Iran

BACKGROUND

Patients with Type 2 Diabetes Mellitus (T2DM) are at a higher risk of polypharmacy and more susceptible to irrational prescriptions; therefore, pharmacological therapy patterns are important to be monitored. The primary objective of this study was to highlight current prescription patterns in T2DM patients and compare them with existing Standards of Medical Care in Diabetes. The second objective was to analyze whether age and gender affect prescription patterns.

METHOD

This cross-sectional study was conducted using the Iran Health Insurance Organization (IHIO) prescription database. It was mined by an Association Rule Mining (ARM) technique, FP-Growth, in order to find co-prescribed drugs with anti-diabetic medications. The algorithm was implemented at different levels of the Anatomical Therapeutic Chemical (ATC) classification system, which assigns different codes to drugs based on their anatomy, pharmacological, therapeutic, and chemical properties to provide an in-depth analysis of co-prescription patterns.

RESULTS

Altogether, the prescriptions of 914,652 patients were analyzed, of whom 91,505 were found to have diabetes. According to our results, prescribing Lipid Modifying Agents (C10) (56.3%), Agents Acting on The Renin-Angiotensin System (C09) (48.9%), Antithrombotic Agents (B01) (35.7%), and Beta Blocking Agents (C07) (30.1%) were meaningfully associated with the prescription of Drugs Used in Diabetes. Our study also revealed that female diabetic patients have a higher lift for taking Thyroid Preparations, and the older the patients were, the more they were prone to take neuropathy-related medications. Additionally, the results suggest that there are gender differences in the association between aspirin and diabetes drugs, with the differences becoming less pronounced in old age.

CONCLUSIONS

Almost all of the association rules found in this research were clinically meaningful, proving the potential of ARM for co-prescription pattern discovery. Moreover, implementing level-based ARM was effective in detecting difficult-to-spot rules. Additionally, the majority of drugs prescribed by physicians were consistent with the Standards of Medical Care in Diabetes.

MiR-770-5p, miR-661 and miR-571 expression level in serum and tissue samples of foot ulcer caused by diabetes mellitus type II in Iranian population

BACKGROUND

Microvascular complications related to diabetes mellitus type II such as foot ulcers are the reason of many mortalities among T2DM patients. The role of microRNAs (miRNAs, miRs) as potent regulators of gene expression is studied in different diseases such as diabetes mellitus and primary studies revealed their importance as early detecting biomarkers. Therefore, in this study it is tried to evaluate the expression level of some miRNAs (miR-770-5p, miR-661 and miR-571) in serum and tissue samples of T2DM related foot ulcer among Iranian patients.

METHODS

30 samples of blood and 30 muscle tissue were collected from T2DM patients suffering foot ulcer (T2DM + FU), 30 blood samples collected from T2DM patients without foot ulcer (T2DM-FU). 30 tissue samples collected from patients with trauma and 30 blood samples were selected as healthy controls.

RESULTS

The three studied miRNAs were statistically significant in all groups in comparison to control blood group. Also, comparison between other groups showed a significant increase of all studied miRNAs especially in the blood and tissues of T2DM + FU patients. The only significant correlation detected between the FBS level and miR-571 expression pattern in blood samples of T2DM + FU group. Finally, the results showed that miR-571, -661, and -770 has a statistically significant discriminative character for differentiating T2DM + FU patients from T2DM-FU both in tissue and blood samples.

CONCLUSION

Although more studies are essential for certifying these findings, our results showed that miR-770-5p, miR-661 and miR-571 are correlated with the microvascular complications related with T2DM such as foot ulcer.

miRNA-770-5p expression is upregulated in patients with type 2 diabetes and miRNA-770-5p knockdown protects pancreatic β-cell function via targeting BAG5 expression

MicroRNA (miR)-770-5p expression is increased in patients with type 2 diabetes mellitus (T2DM) compared with healthy controls; however, the roles and molecular mechanism underlying miR-770-5p in T2DM are not completely understood. In the present study, the reverse transcription-quantitative PCR (RT-qPCR) results indicated that miR-770-5p expression was significantly increased and Bcl-2 associated athanogene 5 (BAG5) expression was significantly decreased in the serum of patients with T2DM compared with healthy volunteers. TargetScan and a dual luciferase reporter gene system were used to predict and verify BAG5 as a target gene of miR-770-5p. Additionally, the RT-qPCR results demonstrated that miR-770-5p expression was significantly increased and BAG5 expression was significantly decreased in uric acid (UA)-treated Min6 cells compared with control cells. Min6 cells were transfected with miR-770-5p inhibitor and BAG5-small interfering (si)RNA to alter expression levels. The results indicated that miR-770-5p negatively regulated BAG5. The effect of miR-770-5p knockdown on UA-induced pancreatic β-cell damage and dysfunction was subsequently assessed. Min6 cells were transfected with miR-770-5p inhibitor or miR-770-5p inhibitor + BAG5-siRNA for 48 h, followed by treatment with or without 5 mg/dl UA for 24 h. Cell viability, apoptosis, apoptosis-related factor expression levels and insulin secretion were assessed. The results demonstrated that UA treatment significantly reduced cell viability, increased cell apoptosis and reduced insulin secretion in Min6 cells compared with the control group. miR-770-5p inhibitor significantly attenuated UA-induced injury and dysfunction of Min6 cells, whereas BAG5 knockdown abolished the protective effects of miR-770-5p inhibitor on UA-damaged Min6 cells. In conclusion, miR-770-5p was highly expressed in the serum of patients with T2DM compared with healthy volunteers. In UA-treated pancreatic β-cells, compared with the inhibitor control group, miR-770-5p knockdown regulated the expression of apoptosis-related genes, increased cell viability, inhibited cell apoptosis and increased insulin secretion by targeting BAG5. Therefore, the present study suggested that miR-770-5p inhibitor may serve a protective role in T2DM.

miR-124-3p Down-Regulation Influences Pancreatic-β-Cell Function by Targeting Secreted Frizzled-Related Protein 5 (SFRP5) in Diabetes Mellitus

Diabetes mellitus (DM) is a complex metabolic disease characterized by hyperglycemia, insulin resistance and pancreatic β-cell dysfunction. There are evidences showed that microRNAs (miRNAs) play important roles in DM. The purpose of our study was to determine the role of miR-124-3p in DM. Quantitative reverse transcription PCR (qRT-PCR) was applied to measure the level of miR- 124-3p in peripheral blood from healthy control patients and DM patients. Then we explored the effects of miR-124-3p inhibitor on the secretion of insulin of pancreatic β-cells. Moreover, we determined the effects of miR-124-3p inhibitor on the apoptosis and viability of pancreatic β-cells through flow cytometry and MTT assay. And we also used western blotting to detect the protein expression of cleaved-caspase3/pro-caspase3, and the activity of caspase3 was detected. In addition, we confirmed the direct target of miR-124-3p using Dual luciferase reporter assay. Our data showed that in the blood of DM patients, SFRP5 was significantly reduced, while miR-124-3p was increased significantly. Furthermore, we found that down-regulation of miR-124-3p increased total insulin content in INS-1 cells, enhanced insulin secretion in INS-1 cells. Furthermore, we revealed that miR-124-3p inhibitor enhanced INS-1 cell viability, decreased apoptosis of INS-1 cells, increased pro-caspase3 expression, decreased cleaved-caspase3 expression and caspase3 activity. In addition, we proved SFRP5 was a direct target of miR-124-3p in pancreatic β-cells. Moreover, SFRP5-siRNA reversed all the effects of miR-124-3p knockdown on pancreatic β-cells.

Regulation of Vascular Function and Inflammation via Cross Talk of Reactive Oxygen and Nitrogen Species from Mitochondria or NADPH Oxidase-Implications for Diabetes Progression

Oxidative stress plays a key role for the development of cardiovascular, metabolic, and neurodegenerative disease. This concept has been proven by using the approach of genetic deletion of reactive oxygen and nitrogen species (RONS) producing, pro-oxidant enzymes as well as by the overexpression of RONS detoxifying, antioxidant enzymes leading to an amelioration of the severity of diseases. Vice versa, the development and progression of cardiovascular diseases is aggravated by overexpression of RONS producing enzymes as well as deletion of RONS detoxifying enzymes. We have previously identified cross talk mechanisms between different sources of RONS, which can amplify the oxidative stress-mediated damage. Here, the pathways and potential mechanisms leading to this cross talk are analyzed in detail and highlighted by selected examples from the current literature and own data including hypoxia, angiotensin II (AT-II)-induced hypertension, nitrate tolerance, aging, and others. The general concept of redox-based activation of RONS sources via “kindling radicals” and enzyme-specific “redox switches” as well as the interaction with redox-sensitive inflammatory pathways are discussed. Here, we present evidence for the existence of such cross talk mechanisms in the setting of diabetes and critically assess their contribution to the severity of diabetic complications.

Environmental aircraft noise aggravates oxidative DNA damage, granulocyte oxidative burst and nitrate resistance in Ogg1-/- mice

Background: Large epidemiological studies point towards a link between the incidence of arterial hypertension, ischaemic heart disease, metabolic disease and exposure to traffic noise, supporting the role of noise exposure as an independent cardiovascular risk factor. We characterised the underlying molecular mechanisms leading to noise-dependent adverse effects on the vasculature and myocardium in an animal model of aircraft noise exposure and identified oxidative stress and inflammation as central players in mediating vascular and cardiac dysfunction. Here, we studied the impact of noise-induced oxidative DNA damage on vascular function in DNA-repair deficient 8-oxoguanine glycosylase knockout (Ogg1^-/-) mice.Methods and results: Noise exposure (peak sound levels of 85 and mean sound level of 72 dB(A) applied for 4d) caused oxidative DNA damage (8-oxoguanine) and enhanced NOX-2 expression in C57BL/6 mice with synergistic increases in Ogg1^-/- mice (shown by immunohistochemistry). A similar pattern was found for oxidative burst of blood leukocytes and other markers of oxidative stress (4-hydroxynonenal, 3-nitrotyrosine) and inflammation (cyclooxygenase-2). We observed additive impairment of noise exposure and genetic Ogg1 deficiency on endothelium-independent relaxation (nitroglycerine), which may be due to exacerbated oxidative DNA damage leading to leukocyte activation and oxidative aldehyde dehydrogenase inhibition.Conclusions: The finding that chronic noise exposure causes oxidative DNA damage in mice is worrisome since these potential mutagenic lesions could contribute to cancer progression. Human field studies have to demonstrate whether oxidative DNA damage is also found in urban populations with high levels of noise exposure as recently shown for workers with high occupational noise exposure.

Effects of synbiotic supplementation on gut microbiome, serum level of TNF-α, and expression of microRNA-126 and microRNA-146a in patients with type 2 diabetes mellitus: study protocol for a double-blind controlled randomized clinical trial

BACKGROUND

The dramatic increase in the prevalence of type 2 diabetes mellitus (T2DM) is a global major challenge to health. Circulating microRNAs have been suggested as promising biomarkers for different disorders such as diabetes. Imbalances in the gut microbiome have been revealed to contribute to the progression of multiple diseases including T2DM. Recently, the consumption of probiotics and synbiotics in the treatment of various diseases has shown a substantial growth. The anti-diabetes and anti-inflammatory effects of synbiotics have been indicated, which may be due to their beneficial effects on the gut microbiome. However, further research is needed to assess the effects of synbiotics on the microbiota and their impacts on expression of microRNAs relating to T2DM. Thus, we will aim to assess the effects of synbiotics on microbiota, serum level of tumor necrosis factor-α (TNF-α), and expression of microRNA-126 and microRNA-146a in patients with T2DM.

METHODS

Seventy-two patients with T2DM will be recruited in this double-blind randomized parallel placebo-controlled clinical trial. After block matching based on age and sex, participants will be randomly assigned to receive 1000 mg/day synbiotic (Familact) or placebo for 12 weeks. The microRNA-126 and microRNA-146a expression levels will be measured by real-time polymerase chain reaction and serum TNF-α level will be assessed by enzyme-linked immunosorbent assay kit at the beginning and at the end of the study. Determination of the gut microbiota will be done by quantitative polymerase chain reaction methods at baseline and at the end of the trial. Biochemical assessments (glycemic and lipid profiles) will also be conducted at onset and end of the study.

DISCUSSION

This is the first randomized controlled trial that will determine the effect of synbiotic supplementation on the gut microbiota and its probable impacts on serum levels of TNF-α and expression of related microRNAs in patients with T2DM.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials: IRCT20180624040228N2. Registered on 27 March 2019. http://www.irct.ir/trial/38371.

Therapeutic Implications of Nitrite in Hypertension

Nitrite, an anion produced from the oxidative breakdown of nitric oxide (NO), has traditionally been viewed as an inert molecule. However, this dogma has been challenged with the findings that nitrite can be readily reduced to NO under pathological conditions, hence representing a physiologically relevant storage reservoir of NO either in the blood or tissues. Nitrite administration has been demonstrated to improve myocardial function in subjects with heart failure and to lower the blood pressure in hypertensive subjects. Thus, extensive amount of work has since been carried out to investigate the therapeutic potential of nitrite in treating cardiovascular diseases, especially hypertension. Studies done on several animal models of hypertension have demonstrated the efficacy of nitrite in preventing and ameliorating the pathological changes associated with the disease. This brief review of the current findings aims to re-evaluate the use of nitrite for the treatment of hypertension and in particular to highlight its role in improving endothelial function.

Vascular Inflammation and Oxidative Stress: Major Triggers for Cardiovascular Disease

Cardiovascular disease is a leading cause of death and reduced quality of life, proven by the latest data of the Global Burden of Disease Study, and is only gaining in prevalence worldwide. Clinical trials have identified chronic inflammatory disorders as cardiovascular risks, and recent research has revealed a contribution by various inflammatory cells to vascular oxidative stress. Atherosclerosis and cardiovascular disease are closely associated with inflammation, probably due to the close interaction of inflammation with oxidative stress. Classical therapies for inflammatory disorders have demonstrated protective effects in various models of cardiovascular disease; especially established drugs with pleiotropic immunomodulatory properties have proven beneficial cardiovascular effects; normalization of oxidative stress seems to be a common feature of these therapies. The close link between inflammation and redox balance was also supported by reports on aggravated inflammatory phenotype in the absence of antioxidant defense proteins (e.g., superoxide dismutases, heme oxygenase-1, and glutathione peroxidases) or overexpression of reactive oxygen species producing enzymes (e.g., NADPH oxidases). The value of immunomodulation for the treatment of cardiovascular disease was recently supported by large-scale clinical trials demonstrating reduced cardiovascular mortality in patients with established atherosclerotic disease when treated by highly specific anti-inflammatory therapies (e.g., using monoclonal antibodies against cytokines). Modern antidiabetic cardiovascular drugs (e.g., SGLT2 inhibitors, DPP-4 inhibitors, and GLP-1 analogs) seem to share these immunomodulatory properties and display potent antioxidant effects, all of which may explain their successful lowering of cardiovascular risk.

DJ‑1 alleviates high glucose‑induced endothelial cells injury via PI3K/Akt‑eNOS signaling pathway

Hyperglycemia mediated endothelial cells (ECs) injury is closely associated with diabetic vascular complications. It was revealed that DJ‑1 possesses cellular protective effects by suppressing oxidative stress. The present study aimed to investigate the beneficial effects of DJ‑1 on high glucose (HG)‑induced human umbilical vein endothelial cell (HUVEC) injury and to elucidate its underlying mechanisms. HUVECs were incubated under 5.5 mM (control group) or 25 mM D‑glucose (HG group) and then transfected with recombinant adenoviral vectors to overexpression of DJ‑1. Cell proliferation and apoptosis were measured using the EdU incorporation assay and flow cytometry with Annexin V-FITC/propidium iodide double staining, respectively. Apoptotic‑related proteins were determined using western blot analysis. Reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) and nitric oxide (NO) levels, the content of malondialdehyde (MDA), and the activities of superoxide dismutase (SOD) were measured. Results demonstrated that overexpression of DJ‑1 promoted cell proliferation and inhibited HUVECs apoptosis stimulated by HG. DJ‑1 also suppressed the HG‑induced reduction in the Bcl‑2/Bax ratio and HG activated ROS generation in HUVECs. Furthermore, HG significantly increased the levels of LDH and MDA, and reduced the level of SOD; however, these effects were reversed by Ad‑DJ‑1 transfection. Furthermore, the cellular protective effect of overexpression of DJ‑1 enhanced p‑Akt/Akt ratio, eNOS activation and NO production, and these trends were partially reversed by a phosphatidylinositol‑4,5‑bisphosphate 3‑kinase (PI3K) inhibitor (LY294002). Taken together, the present study highlighted the involvement of DJ‑1 in HG‑related EC injury and identified that DJ‑1 exerts a cellular protective effect in HUVECs exposed to HG induced oxidative stress via activation of the PI3K/Akt‑eNOS signaling pathway.

Crosstalk of mitochondria with NADPH oxidase via reactive oxygen and nitrogen species signalling and its role for vascular function

Cardiovascular diseases are associated with and/or caused by oxidative stress. This concept has been proven by using the approach of genetic deletion of reactive species producing (pro-oxidant) enzymes as well as by the overexpression of reactive species detoxifying (antioxidant) enzymes leading to a marked reduction of reactive oxygen and nitrogen species (RONS) and in parallel to an amelioration of the severity of diseases. Likewise, the development and progression of cardiovascular diseases is aggravated by overexpression of RONS producing enzymes as well as deletion of antioxidant RONS detoxifying enzymes. Thus, the consequences of the interaction (redox crosstalk) of superoxide/hydrogen peroxide produced by mitochondria with other ROS producing enzymes such as NADPH oxidases (Nox) are of outstanding importance and will be discussed including the consequences for endothelial nitric oxide synthase (eNOS) uncoupling as well as the redox regulation of the vascular function/tone in general (soluble guanylyl cyclase, endothelin-1, prostanoid synthesis). Pathways and potential mechanisms leading to this crosstalk will be analysed in detail and highlighted by selected examples from the current literature including hypoxia, angiotensin II-induced hypertension, nitrate tolerance, aging and others. The general concept of redox-based activation of RONS sources via "kindling radicals" and enzyme-specific "redox switches" will be discussed providing evidence that mitochondria represent key players and amplifiers of the burden of oxidative stress.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Increased serum microRNAs are closely associated with the presence of microvascular complications in type 2 diabetes mellitus

Circulating microRNAs (miRNAs) are emerging biomarkers for type 2 diabetes mellitus (T2DM). However, a comprehensive characterization of the serum miRNA profile in patients with T2DM-associated microvascular disease (T2DMC) has rarely been reported. In this study, we obtained serum samples from 184 T2DM patients (92 with microvascular complications and 92 free of complications) and 92 age/gender-matched controls. The levels of 754 miRNAs were initially analyzed using a TaqMan Low Density Array (TLDA) in three pooled samples from 24 T2DM patients, 24 T2DMC patients and 24 controls. Markedly upregulated miRNAs in the patients' groups were subsequently validated individually by quantitative reverse-transcription PCR (RT-qPCR) in the same samples used for TLDA and further confirmed in another larger cohort consisting of 68 patients with T2DM, 68 patients with T2DMC and 68 controls. Five miRNAs were significantly upregulated in T2DM patients (p < 0.05) including miR-661, miR-571, miR-770-5p, miR-892b and miR-1303. Moreover, the levels of the five miRNAs were higher in patients with complications than in those without complications. Regression analyses revealed the five miRNAs were significantly correlated with microvascular complications (p < 0.05). The five serum miRNAs identified in our study hold potential as auxiliary biomarkers and novel risk factors for T2DM-associated microvascular complications.

Redox implications in adipose tissue (dys)function--A new look at old acquaintances

Obesity is an energy balance disorder associated with dyslipidemia, insulin resistance and diabetes type 2, also summarized with the term metabolic syndrome or syndrome X. Increasing evidence points to “adipocyte dysfunction”, rather than fat mass accretion per se, as the key pathophysiological factor for metabolic complications in obesity. The dysfunctional fat tissue in obesity characterizes a failure to safely store metabolic substrates into existing hypertrophied adipocytes and/or into new preadipocytes recruited for differentiation. In this review we briefly summarize the potential of redox imbalance in fat tissue as an instigator of adipocyte dysfunction in obesity. We reveal the challenge of the adipose redox changes, insights in the regulation of healthy expansion of adipose tissue and its reduction, leading to glucose and lipids overflow.

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Adipose tissue (AT) buffers nutrient excess determining overall metabolic health.

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Redox insight in lipid storage and adipogenesis of AT is reviewed.

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Redox modulation of AT as therapeutic target in obesity/syndrome X is considered.

Beneficial effects of inorganic nitrate/nitrite in type 2 diabetes and its complications

Background and aim

The ability of inorganic nitrate and nitrite to convert to nitric oxide (NO), and some of its properties e.g. regulation of glucose metabolism, vascular homeostasis, and insulin signaling pathway, have recently raised the hypothesis that inorganic nitrate and nitrite could be potential therapeutic agents in type 2 diabetes. In this review, we reviewed experimental and clinical studies investigating the effect of nitrate/nitrite administration on various aspects of type 2 diabetes.

Findings

Studies showed that an altered metabolism of nitrate/nitrite and impaired NO pathway occurs in diabetes which could contribute to its complications. Some important beneficial properties, including regulation of glucose homeostasis and insulin signaling pathway, improvement of insulin resistance and vascular function, hypotensive, hypolipidemic as well as anti-inflammatory and anti-oxidative effects have been observed following administration of inorganic nitrate/nitrite.

Conclusion

It seems that dietary nitrate/nitrite could be a compensatory fuel for a disrupted nitrate/nitrite/NO pathway and related disorders in diabetes. Although some beneficial properties of nitrate/nitrite have been reported by experimental investigations, long-term clinical studies with various doses of inorganic nitrate/nitrite supplementation, are recommended to confirm these effects.

miRNA-130b is required for the ERK/FOXM1 pathway activation-mediated protective effects of isosorbide dinitrate against mesenchymal stem cell senescence induced by high glucose

The present study was carried out to investigate the hypothesis that organic nitrates can attenuate the senescence of mesenchymal stem cells (MSCs), a superior cell source involved in the regeneration and repair of damaged tissue. MSCs were treated with high glucose (HG) in order to induce senescence, which was markedly attenuated by pre-treatment with isosorbide dinitrate (ISDN), a commonly used nitrate, as indicated by senescence-associated galactosidase (SA-β-gal) activity, p21 expression, as well as by the mRNA levels of DNA methyltransferase 1 (DNMT1) and differentiated embryo chondrocyte expressed gene 1 (DEC1), which are senescence-related biomarkers. It was also found that the senescent MSCs (induced by HG glucose) exhibited a marked downregulation in ERK activity and forkhead box M1 (FOXM1) expression, which was reversed by ISDN preconditioning. Of note, the inhibition of ERK phosphorylation or the downregulation of FOXM1 statistically abolished the favourable effects of ISDN. In addition, the investigation of the senescence-associated miR-130 family suggested that miR-130b mediates the beneficial effects of ISDN; it was found that the protective effects of ISDN against the senescence of MSCs were prominently reversed by the knockdown of miR-130b. Furthermore, the downregulation of ERK phosphorylation or FOXM1 expression decreased the miR-130b expression level; however, the suppression of miR-130b demonstrated no significant impact on ERK phosphorylation or FOXM1 expression. Taken together, to the best of our knowledge, the present study is the first to demonstrate the favourable effects of ISDN against HG-induced MSC senescence, which are mediated through the activation of the ERK/FOXM1 pathway and the upregulation of miR-130b.

Effect of rosuvastatin on hyperuricemic rats and the protective effect on endothelial dysfunction

Endothelial dysfunction plays a key role in the development of cardiovascular diseases, renal injuries and hypertension induced by hyperuricemia. Therapies targeting uric acid (UA) may be beneficial in cardiovascular diseases. In the present study, the effect of rosuvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, was investigated to determine whether rosuvastatin improves endothelial dysfunction via the endothelial nitric oxide (NO) pathway and delays the pathogenesis of endothelial dysfunction in hyperuricemic rats. A total of 72 Sprague-Dawley rats (age, 8 weeks) were randomly divided into six groups (12 rats per group), including the control, model, 2.5 mg/kg/day rosuvastatin, 5 mg/kg/day rosuvastatin, 10 mg/kg/day rosuvastatin and 53.57 mg/kg/day allopurinol groups. The model, rosuvastatin and allopurinol rats were subjected to hyperuricemia, induced by the administration of yeast extract powder (21 g/kg/day) and oxonic acid potassium salt (200 mg/kg/day). The hyperuricemic rats were treated with 2.5, 5.0 or 10.0 mg/kg/day rosuvastatin orally for six weeks, while rats treated with allopurinol (53.57 mg/kg/day) were used as a positive control. The serum levels of NO and the gene expression levels of endothelial NO synthase in the aortic tissue increased, whereas the serum levels of UA, endothelin-1 and angiotensin II decreased in the hyperuricemic rats treated with rosuvastatin, particularly at a high rosuvastatin dose (10 mg/kg/day). In addition, the curative effect of the 10 mg/kg/day rosuvastatin group was evidently higher compared with the allopurinol group. Therefore, rosuvastatin may be a novel drug candidate for the treatment of hyperuricemia due to its endothelial protective properties.

Spironolactone improves endothelial dysfunction in streptozotocin-induced diabetic rats

Endothelial dysfunction is a critical initiator for developing diabetic vascular complications. Substantial clinical and experimental evidence suggests that aldosterone plays a crucial role in its pathogenesis. The present study aimed to investigate the effect of the mineralocorticoid receptor (MR) blocker, spironolactone, on diabetes-associated endothelial dysfunction and address the underlying mechanism(s) involved in this setting. Diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ) to rats and spironolactone was orally administered (50 mg/kg/day). Our results showed a marked increase in aortic malondialdehyde (MDA) level and upregulation of the catalytic NADPH oxidase subunit, NOX2 gene expression alongside reducing catalase enzyme capacity, and the serum nitric oxide (NO) bioavailability in diabetic rats. This was associated with a significant reduction in endothelial nitric oxide synthase (eNOS) immunoreactivity and gene expression in diabetic aorta. The transforming growth factor-β (TGF-β) protein and the MR gene expression levels were significantly increased in the diabetic rat aorta. Moreover, the diabetic aorta showed a marked impairment in acetylcholine-mediated endothelium-dependent relaxation. Additionally, spironolactone significantly inhibited the elevated MDA, TGF-β, NOX2, and MR levels alongside correcting the dysregulated eNOS expression and the defective antioxidant function as well as NO bioavailability. Spironolactone markedly reversed the impaired endothelial function in the diabetic aorta. Collectively, our study demonstrates that spironolactone ameliorated the vascular dysfunction of diabetic aorta, at least partially via its anti-inflammatory and anti-oxidative effects alongside correcting the dysregulated eNOS and TGF-β expression. Thus, blockade of MR may represent a useful therapeutic approach against diabetic vasculopathy.

In vitro and in vivo characterization of a new organic nitrate hybrid drug covalently bound to pioglitazone

BACKGROUND/AIMS

Organic nitrates represent a group of nitrovasodilators that are clinically used for the treatment of ischemic heart disease. The new compound CLC-3000 is an aminoethyl nitrate (AEN) derivative of pioglitazone, a thiazolidinedione antidiabetic agent combining the peroxisome proliferator-activated receptor γ agonist activity of pioglitazone with the NO-donating activity of the nitrate moiety.

METHODS

In vitro and in vivo characterization was performed by isometric tension recording, platelet function, bleeding time and detection of oxidative stress.

RESULTS

In vitro, CLC-3000 displayed more potent vasodilation than pioglitazone alone or classical nitrates. In vitro, some effects on oxidative stress parameters were observed. Authentic AEN or the AEN-containing linker CLC-1275 displayed antiaggregatory effects. In vivo treatment with CLC-3000 for 7 days did neither induce endothelial dysfunction nor nitrate tolerance nor oxidative stress. Acute or chronic administration of AEN increased the tail vein bleeding time in mice.

CONCLUSION

In summary, the results of these studies demonstrate that CLC-3000 contains a vasodilative and antithrombotic activity that is not evident with pioglitazone alone, and that 7 days of exposure in vivo showed no typical signs of nitrate tolerance, endothelial dysfunction or other safety concerns in Wistar rats.

Mitochondria as a drug target in ischemic heart disease and cardiomyopathy

Ischemic heart disease is a significant cause of morbidity and mortality in Western society. Although interventions, such as thrombolysis and percutaneous coronary intervention, have proven efficacious in ischemia and reperfusion injury, the underlying pathological process of ischemic heart disease, laboratory studies suggest further protection is possible, and an expansive research effort is aimed at bringing new therapeutic options to the clinic. Mitochondrial dysfunction plays a key role in the pathogenesis of ischemia and reperfusion injury and cardiomyopathy. However, despite promising mitochondria-targeted drugs emerging from the laboratory, very few have successfully completed clinical trials. As such, the mitochondrion is a potential untapped target for new ischemic heart disease and cardiomyopathy therapies. Notably, there are a number of overlapping therapies for both these diseases, and as such novel therapeutic options for one condition may find use in the other. This review summarizes efforts to date in targeting mitochondria for ischemic heart disease and cardiomyopathy therapy and outlines emerging drug targets in this field.