Chronic Administration of Red Yeast Rice Mitigates Endothelial Dysfunction in Spontaneously Hypertensive Rats by Inhibiting Oxidative Stress and Endothelial Nitric Oxide Synthase Uncoupling.

BACKGROUND: Hypertension is associated with endothelial dysfunction. An imbalance in the production of Nitric Oxide (NO) and Reactive Oxygen Species (ROS), leading to impaired NO-cyclic Guanosine Monophosphate (cGMP) pathway, contributes to this disorder. Red Yeast Rice (RYR), produced from the fermentation of rice with Monascus purpureus, is a traditional functional food originating from China. Although recognized for its anti-dyslipidemia properties, there has been growing evidence regarding the anti-hypertensive effects of RYR. However, these studies only focused on its direct and short-term effects. AIM: This study aims to investigate the vasoprotective effects of chronic oral RYR administration using Spontaneously Hypertensive Rats (SHR). MATERIALS AND METHODS: SHR were randomly divided into 3 groups: SHR - Control; SHR - RYR extract (100 mg/kg/day); SHR - lovastatin (10 mg/kg/day). Wistar-Kyoto Rats (WKY) were used as normotensive controls. All animals were treated for 12 weeks by oral gavage. Systolic Blood Pressure (SBP) was measured weekly (tail-cuff method). Vascular reactivity was determined using isolated rat aortic rings in an organ bath. Aortic ROS, NO, tetrahydrobiopterin (BH4 ), and cGMP levels were evaluated. RESULTS: Administration of RYR attenuated SBP elevation and enhanced endothelium-dependent vasodilation in aortic rings. In addition, RYR decreased ROS production and significantly improved the level of vascular NO, BH4, and cGMP. CONCLUSION: In an SHR model, treatment with RYR for 12 weeks exerts an SBP lowering effect that can be attributed to improved vascular function via reduction of oxidative stress, decreased endothelial NO Synthase (eNOS) uncoupling and enhanced NO-cGMP pathway.

Exploring the perspectives of pharmaceutical experts and healthcare practitioners on senolytic drugs for vascular aging-related disorder: a qualitative study.

Objective: The field of targeting cellular senescence with drug candidates to address age-related comorbidities has witnessed a notable surge of interest and research and development. This study aimed to gather valuable insights from pharmaceutical experts and healthcare practitioners regarding the potential and challenges of translating senolytic drugs for treatment of vascular aging-related disorders. Methods: This study employed a qualitative approach by conducting in-depth interviews with healthcare practitioners and pharmaceutical experts. Participants were selected through purposeful sampling. Thematic analysis was used to identify themes from the interview transcripts. Results: A total of six individuals were interviewed, with three being pharmaceutical experts and the remaining three healthcare practitioners. The significant global burden of cardiovascular diseases presents a potentially large market size that offer an opportunity for the development and marketability of novel senolytic drugs. The pharmaceutical sector demonstrates a positive inclination towards the commercialization of new senolytic drugs targeting vascular aging-related disorders. However potential important concerns have been raised, and these include increasing specificity toward senescent cells to prevent off-site targeting, thus ensuring the safety and efficacy of these drugs. In addition, novel senolytic therapy for vascular aging-related disorders may encounter competition from existing drugs that treat or manage risk factors of cardiovascular diseases. Healthcare practitioners are also in favor of recommending the novel senolytic drugs for vascular aging-related disorders but cautioned that its high cost may hinder its acceptance among patients. Besides sharing the same outcome-related concerns as with the pharmaceutical experts, healthcare practitioners anticipated a lack of awareness among the general public regarding the concept of targeting cellular senescence to delay vascular aging-related disorders, and this knowledge gap extends to healthcare practitioner themselves as well. Conclusion: Senolytic therapy for vascular aging-related disorders holds great promise, provided that crucial concerns surrounding its outcomes and commercial hurdles are effectively addressed.

Natural Bioactive Compounds Targeting NADPH Oxidase Pathway in Cardiovascular Diseases.

Cardiovascular disease (CVD) is the leading cause of death worldwide, in both developed and developing countries. According to the WHO report, the morbidity and mortality caused by CVD will continue to rise with the estimation of death going up to 22.2 million in 2030. NADPH oxidase (NOX)-derived reactive oxygen species (ROS) production induces endothelial nitric oxide synthase (eNOS) uncoupling and mitochondrial dysfunction, resulting in sustained oxidative stress and the development of cardiovascular diseases. Seven distinct members of the family have been identified of which four (namely, NOX1, 2, 4 and 5) may have cardiovascular functions. Currently, the treatment and management plan for patients with CVDs mainly depends on the drugs. However, prolonged use of prescribed drugs may cause adverse drug reactions. Therefore, it is crucial to find alternative treatment options with lesser adverse effects. Natural products have been gaining interest as complementary therapy for CVDs over the past decade due to their wide range of medicinal properties, including antioxidants. These might be due to their potent active ingredients, such as flavonoid and phenolic compounds. Numerous natural compounds have been demonstrated to have advantageous effects on cardiovascular disease via NADPH cascade. This review highlights the potential of natural products targeting NOX-derived ROS generation in treating CVDs. Emphasis is put on the activation of the oxidases, including upstream or downstream signalling events.

Epigallocatechin gallate (EGCG) alleviates vascular dysfunction in angiotensin II-infused hypertensive mice by modulating oxidative stress and eNOS.

Epigallocatechin gallate (EGCG) has been shown to have antihypertensive activity. However, the role of epigallocatechin gallate (EGCG) in improving vascular function via modulation of endothelial nitric oxide synthase (eNOS) in hypertensive subjects is not well researched. Angiotensin II-infused hypertensive mice (8-10 weeks old) received EGCG (50 mg/kg/day) for 14 days via oral gavage. The arterial systolic blood pressure (SBP) was measured using the tail-cuff method every three days. At the end of the treatment, the vascular reactivity of the isolated aortae was studied using wire myographs. The level of nitric oxide (NO), cyclic guanosine monophosphate (cGMP) and tetrahydrobiopterine (BH4) were determined using assay kits while the presence of proteins (NOS, p-eNOS and NOx-2) were determined using by Western blotting. In vivo treatment with EGCG for 14 days significantly attenuated the increase in SBP, alleviated the vascular dysfunction, increased the vascular cGMP and BH4 level as well as the expression of p-eNOS and decreased elevated ROS level and NOx-2 protein in angiotensin II-infused hypertensive mice. Collectively, treatment with EGCG in hypertensive mice exerts a blood pressure lowering effect which is partly attributed to the improvement in the vascular function due to its ability to reduce vascular oxidative stress in the aortic tissue leading to a decrease in eNOS uncoupling thus increasing NO bioavailability.

Renal Nano-drug delivery for acute kidney Injury: Current status and future perspectives.

Acute kidney injury (AKI) causes considerable morbidity and mortality, particularly in the case of post-cardiac infarction or kidney transplantation; however, the site-specific accumulation of small molecule reno-protective agents for AKI has often proved ineffective due to dynamic fluid and solute excretion and non-selectivity, which impedes therapeutic efficacy. This article reviews the current status and future trajectories of renal nanomedicine research for AKI management from pharmacological and clinical perspectives, with a particular focus on appraising nanosized drug carrier (NDC) use for the delivery of reno-protective agents of different pharmacological classes and the effectiveness of NDCs in improving renal tissue targeting selectivity and efficacy of said agents. This review reveals the critical shift in the role of the small molecule reno-protective agents in AKI pharmacotherapy - from prophylaxis to treatment - when using NDCs for delivery to the kidney. We also highlight the need to identify the accumulation sites of NDCs carrying reno-protective agents in renal tissues during in vivo assessments and detail the less-explored pharmacological classes of reno-protective agents whose efficacies may be improved via NDC-based delivery. We conclude the paper by outlining the challenges and future perspectives of NDC-based reno-protective agent delivery for better clinical management of AKI.

Roles and Therapeutic Implications of Endoplasmic Reticulum Stress and Oxidative Stress in Cardiovascular Diseases.

In different pathological states that cause endoplasmic reticulum (ER) calcium depletion, altered glycosylation, nutrient deprivation, oxidative stress, DNA damage or energy perturbation/fluctuations, the protein folding process is disrupted and the ER becomes stressed. Studies in the past decade have demonstrated that ER stress is closely associated with pathogenesis of obesity, insulin resistance and type 2 diabetes. Excess nutrients and inflammatory cytokines associated with metabolic diseases can trigger or worsen ER stress. ER stress plays a critical role in the induction of endothelial dysfunction and atherosclerosis. Signaling pathways including AMP-activated protein kinase and peroxisome proliferator-activated receptor have been identified to regulate ER stress, whilst ER stress contributes to the imbalanced production between nitric oxide (NO) and reactive oxygen species (ROS) causing oxidative stress. Several drugs or herbs have been proved to protect against cardiovascular diseases (CVD) through inhibition of ER stress and oxidative stress. The present article reviews the involvement of ER stress and oxidative stress in cardiovascular dysfunction and the potential therapeutic implications.

Biological Activities of Paeonol in Cardiovascular Diseases: A Review.

Paeonol is a naturally existing bioactive compound found in the root bark of Paeonia suffruticosa and it is traditionally used in Chinese medicine for the prevention and management of cardiovascular diseases. To date, a great deal of studies has been reported on the pharmacological effects of paeonol and its mechanisms of action in various diseases and conditions. In this review, the underlying mechanism of action of paeonol in cardiovascular disease has been elucidated. Recent studies have revealed that paeonol treatment improved endothelium injury, demoted inflammation, ameliorated oxidative stress, suppressed vascular smooth muscle cell proliferation, and repressed platelet activation. Paeonol has been reported to effectively protect the cardiovascular system either employed alone or in combination with other traditional medicines, thus, signifying it could be a hypothetically alternative or complementary atherosclerosis treatment. This review summarizes the biological and pharmacological activities of paeonol in the treatment of cardiovascular diseases and its associated underlying mechanisms for a better insight for future clinical practices.

Adipogenesis and therapeutic potentials of antiobesogenic phytochemicals: Insights from preclinical studies.

Obesity is one of the most serious public health problems in both developed and developing countries in recent years. While lifestyle and diet modifications are the most important management strategies of obesity, these may be insufficient to ensure long-term weight reduction in certain individuals and alternative strategies including pharmacotherapy need to be considered. However, drugs option remains limited due to low efficacy and adverse effects associated with their use. Hence, identification of safe and effective alternative therapeutic agents remains warranted to combat obesity. In recent years, bioactive phytochemicals are considered as valuable sources for the discovery of new pharmacological agents for the treatment of obesity. Adipocyte hypertrophy and hyperplasia increases with obesity and undergo molecular and cellular alterations that can affect systemic metabolism giving rise to metabolic syndrome and comorbidities such as type 2 diabetes and cardiovascular diseases. Many phytochemicals have been reported to target adipocytes by inhibiting adipogenesis, inducing lipolysis, suppressing the differentiation of preadipocytes to mature adipocytes, reducing energy intake, and boosting energy expenditure mainly in vitro and in animal studies. Nevertheless, further high-quality studies are needed to firmly establish the clinical efficacy of these phytochemicals. This review outlines common pathways involved in adipogenesis and phytochemicals targeting effector molecules of these pathways, the challenges faced and the way forward for the development of phytochemicals as antiobesity agents.

Effect of Hydrolyzed Bird's Nest on ß-Cell Function and Insulin Signaling in Type 2 Diabetic Mice.

Type 2 diabetes mellitus is characterized by both resistance to the action of insulin and defects in insulin secretion. Bird's nest, which is derived from the saliva of swiftlets are well known to possess multiple health benefits dating back to Imperial China. However, it's effect on diabetes mellitus and influence on the actions of insulin action remains to be investigated. In the present study, the effect of standardized aqueous extract of hydrolyzed edible bird nest (HBN) on metabolic characteristics and insulin signaling pathway in pancreas, liver and skeletal muscle of db/db, a type 2 diabetic mice model was investigated. Male db/db diabetic and its euglycemic control, C57BL/6J mice were administered HBN (75 and 150 mg/kg) or glibenclamide (1 mg/kg) orally for 28 days. Metabolic parameters were evaluated by measuring fasting blood glucose, serum insulin and oral glucose tolerance test (OGTT). Insulin signaling and activation of inflammatory pathways in liver, adipose, pancreas and muscle tissue were evaluated by Western blotting and immunohistochemistry. Pro-inflammatory cytokines were measured in the serum at the end of the treatment. The results showed that db/db mice treated with HBN significantly reversed the elevated fasting blood glucose, serum insulin, serum pro-inflammatory cytokines levels and the impaired OGTT without affecting the body weight of the mice in all groups. Furthermore, HBN treatment significantly ameliorated pathological changes and increased the protein expression of insulin, and glucose transporters in the pancreatic islets (GLUT-2), liver and skeletal muscle (GLUT-4). Likewise, the Western blots analysis denotes improved insulin signaling and antioxidant enzyme, decreased reactive oxygen species producing enzymes and inflammatory molecules in the liver and adipose tissues of HBN treated diabetic mice. These results suggest that HBN improves ß-cell function and insulin signaling by attenuation of oxidative stress mediated chronic inflammation in the type 2 diabetic mice.

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.

Flavonoids as Natural Anti-Inflammatory Agents Targeting Nuclear Factor-Kappa B (NFκB) Signaling in Cardiovascular Diseases: A Mini Review.

Cardiovascular diseases (CVDs) such as angina, hypertension, myocardial ischemia, and heart failure are the leading causes of morbidity and mortality worldwide. One of the major transcription factors widely associated with CVDs is nuclear factor-kappa B (NFκB). NFκB activation initiates the canonical and non-conical pathways that promotes activation of transcription factors leading to inflammation, such as leukocyte adhesion molecules, cytokines, and chemokines. Flavonoids are bioactive polyphenolic compounds found abundantly in various fruits, vegetables, beverages (tea, coffee), nuts, and cereal products with cardiovascular protective properties. Flavonoids can be classified into six subgroups based on their chemical structures: flavanones, flavones, flavonols, flavan-3-ols, isoflavones, and anthocyanidins. As NFκB inhibitors, these flavonoids may modulate the expression of pro-inflammatory genes leading to the attenuation of the inflammatory responses underlying various cardiovascular pathology. This review presents an update on the anti-inflammatory actions of flavonoids via inhibition of NFκB mechanism supporting the therapeutic potential of these natural compounds in various CVDs.

Methanolic extract of Mitragyna speciosa Korth leaf inhibits ethanol seeking behaviour in mice: involvement of antidopaminergic mechanism.

In the current study, the effect of methanolic extract of Mitragyna speciosa leaf (MMS) against the rewarding and reinforcing properties of ethanol using a mouse model of conditioned place preference (CPP) and runway model of drug self-administration was studied. Subsequently, the effect of MMS on dopamine level in the nucleus accumbens (NAc) of the mouse brain was further investigated. From the data obtained, MMS (50 and 75 mg/kg, p.o.) significantly reversed the ethanol-place preference in mice, which is similar to the effect observed in the reference drugs acamprosate (300 mg/kg, p.o.) and clozapine (1 mg/kg, p.o.) treatment groups in CPP test. Likewise, the escalating doses of ethanol-conditioned mice reduced the runtime to reach goal box, infers the positive reinforcing effects of alcohol. Interestingly, MMS (50, 75 and 100 mg/kg, p.o.) significantly prolonged the runtime in ethanol-conditioned mice. Besides, MMS (50 and 75 mg/kg, p.o.) and reference drugs; acamprosate (300 mg/kg, p.o.) and clozapine (1 mg/kg, p.o.) treated mice significantly decreased the alcohol-induced elevated dopamine level in the NAc region of the brain. Overall, this study provides first evidence that MMS inhibits ethanol seeking behaviour in mice. Based on these findings, we suggest that Mitragyna speciosa may well be utilized for novel drug development to combat alcohol dependence.

Withaferin A inhibits adipogenesis in 3T3-F442A cell line, improves insulin sensitivity and promotes weight loss in high fat diet-induced obese mice.

The increased prevalence of obesity and associated insulin resistance calls for effective therapeutic treatment of metabolic diseases. The current PPARγ-targeting antidiabetic drugs have undesirable side effects. The present study investigated the anti-diabetic and anti-obesity effects of withaferin A (WFA) in diet-induced obese (DIO) C57BL/6J mice and also the anti-adipogenic effect of WFA in differentiating 3T3- F442A cells. DIO mice were treated with WFA (6 mg/kg) or rosiglitazone (10 mg/kg) for 8 weeks. At the end of the treatment period, metabolic profile, liver function and inflammatory parameters were obtained. Expression of selective genes controlling insulin signaling, inflammation, adipogenesis, energy expenditure and PPARγ phosphorylation-regulated genes in epididymal fats were analyzed. Furthermore, the anti-adipogenic effect of WFA was evaluated in 3T3- F442A cell line. WFA treatment prevented weight gain without affecting food or caloric intake in DIO mice. WFA-treated group also exhibited lower epididymal and mesenteric fat pad mass, an improvement in lipid profile and hepatic steatosis and a reduction in serum inflammatory cytokines. Insulin resistance was reduced as shown by an improvement in glucose and insulin tolerance and serum adiponectin. WFA treatment upregulated selective insulin signaling (insr, irs1, slc2a4 and pi3k) and PPARγ phosphorylation-regulated (car3, selenbp1, aplp2, txnip, and adipoq) genes, downregulated inflammatory (tnf-α and il-6) genes and altered energy expenditure controlling (tph2 and adrb3) genes. In 3T3- F442A cell line, withaferin A inhibited adipogenesis as indicated by a decrease in lipid accumulation in differentiating adipocytes and protein expression of PPARγ and C/EBPα. The effect of rosiglitazone on physiological and lipid profiles, insulin resistance, some genes expression and differentiating adipocytes were markedly different. Our data suggest that WFA is a promising therapeutic agent for both diabetes and obesity.

Differential effects of dietary flavonoids on adipogenesis.

PROPOSE: Obesity is a fast growing epidemic worldwide. During obesity, the increase in adipose tissue mass arise from two different mechanisms, namely, hyperplasia and hypertrophy. Hyperplasia which is the increase in adipocyte number is characteristic of severe obese patients. Recently, there has been much interest in targeting adipogenesis as therapeutic strategy against obesity. Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development. METHODS: Presently, we provide a review of key studies evaluating the effects of dietary flavonoids in different stages of adipocyte development with a particular emphasis on the investigations that explore the underlying mechanisms of action of these compounds in human or animal cell lines as well as animal models. RESULTS: Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development. Although most of the studies reveal anti-adipogenic effect of flavonoids, some flavonoids demonstrated proadipogenic effect in mesenchymal stem cells or preadipocytes. CONCLUSION: The anti-adipogenic effect of flavonoids is mainly via their effect on regulation of several pathways such as induction of apoptosis, suppression of key adipogenic transcription factors, activation of AMPK and Wnt pathways, inhibition of clonal expansion, and cell-cycle arrest.

Edible Bird's Nest Protects Against Hyperglycemia-Induced Oxidative Stress and Endothelial Dysfunction.

Increased oxidative stress by hyperglycemia is a major cause of vascular complications in diabetes. Bird's nest, which is made from the saliva of swiftlets has both medicinal and nutritional values dated back to ancient China. However, its role in improving endothelial dysfunction due to diabetes is yet to be elucidated. The present study examined the protective effect and mechanism of action of the aqueous extract of hydrolyzed edible bird nest (HBN) on endothelium in models of diabetes, in vitro and in vivo. Male db/m+ and db/db mice were orally administered with or without HBN and glibenclamide for 28 days, followed by vascular reactivity studies in mouse aortas. Human umbilical vein endothelial cells (HUVECs) and isolated mouse aorta from C57BL/6J were treated with high glucose (HG), HBN, sialic acid (SA), glibenclamide, and apocynin, respectively. The effects of HBN on reactive oxygen species (ROS) production and nitric oxide (NO) bioavailability were assessed by Western blot, 2',7'-dichlorofluorescin-diacetate (DCF-DA), and 4-amino-5-methylamino-2',7' difluorofluorescein (DAF-FM DA) in HUVECs, isolated mouse aorta, and db/db diabetic mice. HBN significantly reversed the endothelial dysfunction in diabetic mice and isolated mouse aorta. HBN normalized ROS over-production of NOX2 and nitrotyrosine, reversed the reduction of anti-oxidant marker, SOD-1 as well as restored NO bioavailability in both HUVECs challenged with HG and in db/db diabetic mice. Similarly, HG-induced elevation of oxidative stress in HUVECs were reversed by SA, glibenclamide, and apocynin. This attests that HBN restores endothelial function and protects endothelial cells against oxidative damage induced by HG in HUVECs, isolated mouse aorta, and db/db diabetic mice via modulating ROS mechanism, which subsequently increases NO bioavailability. This result demonstrates the potential role of HBN in preserving endothelial function and management of micro- or macrovascular complications in diabetes.

Natural products targeting ER stress pathway for the treatment of cardiovascular diseases.

Endoplasmic reticulum (ER) is the main organelle for the synthesis, folding, and processing of secretory and transmembrane proteins. Pathological stimuli including hypoxia, ischaemia, inflammation and oxidative stress interrupt the homeostatic function of ER, leading to accumulation of unfolded proteins, a condition referred to as ER stress. ER stress triggers a complex signalling network referred as the unfolded protein response (UPR). Extensive studies have demonstrated that ER stress plays an important role in the pathogenesis of various cardiovascular diseases such as heart failure, ischemic heart disease and atherosclerosis. The importance of natural products in modern medicine are well recognized and continues to be of interests as a source of novel lead compounds. Natural products targeting components of UPR and reducing ER stress offers an innovative strategic approach to treat cardiovascular diseases. In this review, we discussed several therapeutic interventions using natural products with potential cardiovascular protective properties targeting ER stress signalling pathways.

Paeonol Attenuates LPS-Induced Endothelial Dysfunction and Apoptosis by Inhibiting BMP4 and TLR4 Signaling Simultaneously but Independently.

Inflammatory injury of the endothelium leads to apoptosis and endothelial dysfunction. The current study explored the effect and mechanisms of paeonol in inflammation-induced apoptosis and endothelial dysfunction induced by lipopolysaccharides (LPSs). The effects of paeonol on LPS-induced inflammatory injury were assessed by Western blotting, flow cytometry and reactive oxygen species (ROS) measurement in human umbilical vein endothelial cells (HUVECs) and C57BL/6J mice. Vascular reactivity of isolated mouse aortae was examined using wire myographs. The exposure of HUVECs to LPS increased the protein presence of Toll-like receptor 4 (TLR4), bone morphogenic protein 4 (BMP4), BMP receptor type 1A, nicotinamide adenine dinucleotide phosphate oxidase subunit 2, mitogen-activated protein kinase (MAPK), inducible nitric oxide synthase (iNOS), and cleaved caspase 3, as well as decreased it in phosphorylated endothelial nitric oxide synthase; these effects were prevented by treatment with paeonol. Similarly, cotreatment with paeonol reversed BMP4-induced apoptosis in HUVECs. Relaxation in response to the endothelium-dependent vasodilator acetylcholine were impaired in mouse aortae after exposure to LPSs; this endothelial dysfunction was reversed by cotreatment with paeonol, noggin (a BMP4 inhibitor), TAK242 (TLR4 antagonist), apocynin (an ROS scavenger), MAPK inhibitors, and AG (an iNOS inhibitor). BMP4 small interfering RNAs (siRNAs) abolished LPS-induced upregulation of BMP4 and cleaved caspase 3 protein, but not in cells treated with TLR4 siRNA and vice versa. The silencing of TLR4 and BMP4 abolished the inhibitory effects of paeonol on LPS-induced activation of cleaved caspase 3. The present results demonstrate that paeonol reduces LPS-induced endothelial dysfunction and apoptosis by inhibiting TLR4 and BMP4 signaling independently.

Chronic administration of sodium nitrite prevents hypertension and protects arterial endothelial function by reducing oxidative stress in angiotensin II-infused mice.

AIM: Endothelial dysfunction accompanied by an increase in oxidative stress is a key event leading to hypertension. As dietary nitrite has been reported to exert antihypertensive effect, the present study investigated whether chronic oral administration of sodium nitrite improves vascular function in conduit and resistance arteries of hypertensive animals with elevated oxidative stress. METHODS: Sodium nitrite (50mg/L) was given to angiotensin II-infused hypertensive C57BL/6J (eight to ten weeks old) mice for two weeks in the drinking water. Arterial systolic blood pressure was measured using the tail-cuff method. Vascular responsiveness of isolated aortae and renal arteries was studied in wire myographs. The level of nitrite in the plasma and the cyclic guanosine monophosphate (cGMP) content in the arterial wall were determined using commercially available kits. The production of reactive oxygen species (ROS) and the presence of proteins (nitrotyrosine, NOx-2 and NOx-4) involved in ROS generation were evaluated with dihydroethidium (DHE) fluorescence and by Western blotting, respectively. RESULTS: Chronic administration of sodium nitrite for two weeks to mice with angiotensin II-induced hypertension decreased systolic arterial blood pressure, reversed endothelial dysfunction, increased plasma nitrite level as well as vascular cGMP content. In addition, sodium nitrite treatment also decreased the elevated nitrotyrosine and NOx-4 protein level in angiotensin II-infused hypertensive mice. CONCLUSIONS: The present study demonstrates that chronic treatment of hypertensive mice with sodium nitrite improves impaired endothelium function in conduit and resistance vessels in addition to its antihypertensive effect, partly through inhibition of ROS production.

Chronic treatment with paeonol improves endothelial function in mice through inhibition of endoplasmic reticulum stress-mediated oxidative stress.

Endoplasmic reticulum (ER) stress leads to endothelial dysfunction which is commonly associated in the pathogenesis of several cardiovascular diseases. We explored the vascular protective effects of chronic treatment with paeonol (2'-hydroxy-4'-methoxyacetophenone), the major compound from the root bark of Paeonia suffruticosa on ER stress-induced endothelial dysfunction in mice. Male C57BL/6J mice were injected intraperitoneally with ER stress inducer, tunicamycin (1 mg/kg/week) for 2 weeks to induce ER stress. The animals were co-administered with or without paeonol (20 mg/kg/oral gavage), reactive oxygen species (ROS) scavenger, tempol (20 mg/kg/day) or ER stress inhibitor, tauroursodeoxycholic acid (TUDCA, 150 mg/kg/day) respectively. Blood pressure and body weight were monitored weekly and at the end of treatment, the aorta was isolated for isometric force measurement. Protein associated with ER stress (GRP78, ATF6 and p-eIF2α) and oxidative stress (NOX2 and nitrotyrosine) were evaluated using Western blotting. Nitric oxide (NO) bioavailability were determined using total nitrate/nitrite assay and western blotting (phosphorylation of eNOS protein). ROS production was assessed by en face dihydroethidium staining and lucigenin-enhanced chemiluminescence assay, respectively. Our results revealed that mice treated with tunicamycin showed an increased blood pressure, reduction in body weight and impairment of endothelium-dependent relaxations (EDRs) of aorta, which were ameliorated by co-treatment with either paeonol, TUDCA and tempol. Furthermore, paeonol reduced the ROS level in the mouse aorta and improved NO bioavailability in tunicamycin treated mice. These beneficial effects of paeonol observed were comparable to those produced by TUDCA and tempol, suggesting that the actions of paeonol may involve inhibition of ER stress-mediated oxidative stress pathway. Taken together, the present results suggest that chronic treatment with paeonol preserved endothelial function and normalized blood pressure in mice induced by tunicamycin in vivo through the inhibition of ER stress-associated ROS.