The relationship of salusins with Parkinson's Disease, Alzheimer's Disease, and acute ischemic stroke: A preliminary study

Neuroinflammation, oxidative stress, and apoptosis play important roles in the pathophysiology of Alzheimer's Disease (AD), Parkinson's Disease (PD), and Acute Ischemic Stroke (AIS). Salusin-α and salusin-β peptides, which were shown to be present in many tissues, including the central nervous system, were also shown to be associated with apoptosis, inflammation, and oxidative stress. In the present study, the relationship between Salusin-α and salusin-β peptides and AD, PD, and AIS were investigated. A total of 179 people were included in the present study, including 46 AD, 44 PD, 42 AIS, and 47 controls. Plasma Salusin-α and salusin-β levels were measured with the ELISA Method. The plasma salusin-β levels of AD, PD, and AIS patients were lower than the control group at significant levels (p < 0.05). It was also found that there were correlations between salusin-α and salusin-β levels and age, triglyceride, LDL-c, total cholesterol, and hemoglobin levels. In this study, we found that salusin- β, an endogenous neuropeptide, was associated with AD, PD and AIS. The low level of salusin-β in these diseases in which neuronal damage occurs may be related to the neuroprotective properties of this endogenous peptide. Further studies are needed to fully understand the relationship between salusin-β and the pathophysiology of these diseases.

Upregulated expression of a TOR2A gene product-salusin-β in the paraventricular nucleus enhances sympathetic activity and cardiac sympathetic afferent reflex in rats with chronic heart failure induced by coronary artery ligation

AIM

Enhanced cardiac sympathetic afferent reflex (CSAR) promotes sympathetic hyperactivation in chronic heart failure (CHF). Salusin-β is a torsin family 2 member A (TOR2A) gene product and a cardiovascular active peptide closely associated with cardiovascular diseases. We aimed to determine the roles of salusin-β in the paraventricular nucleus (PVN) in modulating enhanced CSAR and sympathetic hyperactivation in rats with CHF induced by coronary artery ligation and elucidate the underlying molecular mechanisms.

METHODS

CSAR was evaluated based on the responses of mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) to the epicardial administration of capsaicin in rats under anesthesia.

RESULTS

Salusin-β protein expression was upregulated in the PVN of the CHF compared with sham-operated rats. Salusin-β microinjection into the PVN dose-dependently increased MAP and RSNA and enhanced CSAR, while anti-salusin-β IgG exerted opposite effects. The effect of salusin-β was inhibited by reactive oxygen species (ROS) scavenger or NAD(P)H oxidase inhibitor but promoted by superoxide dismutase inhibitor. The effect of anti-salusin-β IgG was interdicted by nitric oxide (NO) synthase inhibitor. Furthermore, chronic salusin-β gene knockdown in PVN attenuated CSAR, reduced sympathetic output, improved myocardial remodeling and cardiac function, decreased NAD(P)H oxidase activity and ROS levels, and increased NO levels in the CHF rats.

CONCLUSION

Increased salusin-β activity in the PVN contributes to sympathetic hyperactivation and CSAR in CHF by inhibiting NO release and stimulating NAD(P)H oxidase-ROS production. Reducing endogenous central salusin-β expression might be a novel strategy for preventing and treating CHF in the future.

Salusins: advance in cardiovascular disease research

Salusins are discovered in 2003 and divided into salusin-α and salusin-β, which are bioactive peptides with hemodynamic and mitotic activity and mainly distributed in plasma, urine, endocrine glands and kidneys. A large number of studies have shown that salusins can regulate lipid metabolism, inflammatory response and vascular proliferation. Despite the profound and diverse physiological properties of salusins, the exact mechanism of their cardiovascular effects remains to be determined. The potential mechanisms of action of salusins in cardiovascular-related diseases such as atherosclerosis, hypertension, heart failure, myocardial infarction and myocarditis, and their use as biomarkers of cardiovascular disease are discussed. This review aims to provide a new strategy for the diagnosis and prevention of clinical cardiovascular diseases.

Serum salusin-α and salusin-β levels in patients with psoriatic arthritis

INTRODUCTION

Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by skin lesions and joint involvement. Salusin-α and salusin-β are two new bioactive molecules. It is reported that salusins may have role in regulation of the immune system and inflammation. The aim of our study was to evaluate the serum salusin-α and salusin-β levels in PsA patients and to establish the possible relationship with the disease features.

MATERIAL AND METHODS

Our study included 40 PsA patients who fulfilled the CASPAR criteria and 40 healthy volunteers. Demographic, clinical, laboratory and radiological data and disease activity indices (PASI, BASDAI, BASFI, HAQ) were recorded in all patients. The enzyme-linked immunosorbent assay (ELISA) method was used to measure serum salusin-α and salusin-β levels.

RESULTS

The demographic data were as follows: 13 patients (32.5%) were males and 27 (67.5%) were female, mean age was 48.5 years and mean disease duration was 2.4 years. Patients' history was taken and clinical assessment was performed; 20 (50%) patients had a family history, 18 (45%) patients were smoker, 19 (47.5%) patients had HLA-B27 positivity, 33 (82.5%) had sacroiliitis, 36 (90%) had enthesitis, 23 (57.5%) had distal interphalangeal (DIP) joint and nail involvement, 26 (65%) had wrist involvement, and 11 (27.5%) had ankle involvement. Laboratory data of the patients were recorded; 20 (50%) patients had elevated CRP level and 25 (62.5%) patients had an elevated ESR level. The study results showed that PsA patients had an elevated serum salusin-α level when compared with the control group (p = 0.004). The association between serum salusin-α level and ankle arthritis was found (p = 0.04). Serum levels of salusin-β were similar in PsA patients and controls both (p = 0.285).

CONCLUSIONS

We found elevated serum salusin-α in PsA patients while the serum salusin-β levels were normal. Salusin-α may have a possible role in disease pathogenesis and it may be use as a reliable biomarker in PsA patients. Multicenter prospective studies are needed in this regard.

Asprosin in the Paraventricular Nucleus Induces Sympathetic Activation and Pressor Responses via cAMP-Dependent ROS Production

Asprosin is a newly discovered adipokine that is involved in regulating metabolism. Sympathetic overactivity contributes to the pathogenesis of several cardiovascular diseases. The paraventricular nucleus (PVN) of the hypothalamus plays a crucial role in the regulation of sympathetic outflow and blood pressure. This study was designed to determine the roles and underlying mechanisms of asprosin in the PVN in regulating sympathetic outflow and blood pressure. Experiments were carried out in male adult SD rats under anesthesia. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), and heart rate (HR) were recorded, and PVN microinjections were performed bilaterally. Asprosin mRNA and protein expressions were high in the PVN. The high asprosin expression in the PVN was involved in both the parvocellular and magnocellular regions according to immunohistochemical analysis. Microinjection of asprosin into the PVN produced dose-related increases in RSNA, MAP, and HR, which were abolished by superoxide scavenger tempol, antioxidant N-acetylcysteine (NAC), and NADPH oxidase inhibitor apocynin. The asprosin promoted superoxide production and increased NADPH oxidase activity in the PVN. Furthermore, it increased the cAMP level, adenylyl cyclase (AC) activity, and protein kinase A (PKA) activity in the PVN. The roles of asprosin in increasing RSNA, MAP, and HR were prevented by pretreatment with AC inhibitor SQ22536 or PKA inhibitor H89 in the PVN. Microinjection of cAMP analog db-cAMP into the PVN played similar roles with asprosin in increasing the RSNA, MAP, and HR, but failed to further augment the effects of asprosin. Pretreatment with PVN microinjection of SQ22536 or H89 abolished the roles of asprosin in increasing superoxide production and NADPH oxidase activity in the PVN. These results indicated that asprosin in the PVN increased the sympathetic outflow, blood pressure, and heart rate via cAMP–PKA signaling-mediated NADPH oxidase activation and the subsequent superoxide production.

Intracerebroventricular salusin-β infusion to rats increases hypothalamus-pituitary-testicular axis hormones

Salusin-β (Sal-β), which originates from preprosalusin, is a multifunctional hormone with a peptide structure. Sal-β exists in the hypothalamus and can stimulate the pituitary gland. The present study was conducted to determine the effects of Sal-β on hormones that play roles in the male reproductive system. Forty male Wistar Albino rats were used in the study. No infusions were performed on the control group, and infusions were applied to the infusion groups (artificial cerebrospinal fluid to the sham group, 2 and 20 nM Sal-β to the experimental group) through intracerebroventricular infusion for 7 days at 10 μl/hour rate. The animals were decapitated after 7 days of infusion; and the hypothalamus, testicles, and blood tissue samples were collected. The gonadotropin-releasing hormone (GnRH) mRNA levels were determined from the hypothalamus tissues by using the Real Time-PCR Method, and the serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone levels were determined using the ELISA method. Also, Hematoxylin-Eosin Staining Method was used for histopathological evaluations in the testicle tissues. As a result, Sal-β infusion increased GnRH mRNA levels in hypothalamus tissues (p < 0.05) besides, serum LH, FSH, and testosterone levels of the rats were higher at significant levels following Sal-β infusion compared to the control and sham group (p < 0.05). In the histological examination of the testicle tissues, Sal-β application was found to decrease the seminiferous tubule diameter and germinal epithelial thickness (p < 0.05). This evidence is the first, indicating that Sal-β, which is administered to male rats with central infusion, stimulates hypothalamus and pituitary tissues, and causes increased secretion of male reproductive hormones.

Salusin-β in Intermediate Dorsal Motor Nucleus of the Vagus Regulates Sympathetic-Parasympathetic Balance and Blood Pressure

The dorsal motor nucleus of the vagus (DMV) is known to control vagal activity. It is unknown whether the DMV regulates sympathetic activity and whether salusin-β in the DMV contributes to autonomic nervous activity. We investigated the roles of salusin-β in DMV in regulating sympathetic-parasympathetic balance and its underline mechanisms. Microinjections were carried out in the DMV and hypothalamic paraventricular nucleus (PVN) in male adult anesthetized rats. Renal sympathetic nerve activity (RSNA), blood pressure and heart rate were recorded. Immunohistochemistry for salusin-β and reactive oxidative species (ROS) production in the DMV were examined. Salusin-β was expressed in the intermediate DMV (iDMV). Salusin-β in the iDMV not only inhibited RSNA but also enhanced vagal activity and thereby reduced blood pressure and heart rate. The roles of salusin-β in causing vagal activation were mediated by NAD(P)H oxidase-dependent superoxide anion production in the iDMV. The roles of salusin-β in inhibiting RSNA were mediated by not only the NAD(P)H oxidase-originated superoxide anion production in the iDMV but also the γ-aminobutyric acid (GABA)_A receptor activation in PVN. Moreover, endogenous salusin-β and ROS production in the iDMV play a tonic role in inhibiting RSNA. These results indicate that salusin-β in the iDMV inhibits sympathetic activity and enhances vagal activity, and thereby reduces blood pressure and heart rate, which are mediated by NAD(P)H oxidase-dependent ROS production in the iDMV. Moreover, GABA_A receptor in the PVN mediates the effect of salusin-β on sympathetic inhibition. Endogenous salusin-β and ROS production in the iDMV play a tonic role in inhibiting sympathetic activity.

Knockdown of Salusin-β Improves Cardiovascular Function in Myocardial Infarction-Induced Chronic Heart Failure Rats

Salusin-β is a biologically active peptide with 20 amino acids that exerts several cardiovascular activity-regulating effects, such as regulating vascular endothelial function and the proliferation of vascular smooth muscle cells. However, the regulatory effects of salusin-β in myocardial infarction-induced chronic heart failure (CHF) are still unknown. The current study is aimed at investigating the effects of silencing salusin-β on endothelial function, cardiac function, vascular and myocardial remodeling, and its underlying signaling pathways in CHF rats induced by coronary artery ligation. CHF and sham-operated (Sham) rats were subjected to tail vein injection of adenoviral vectors encoding salusin-β shRNA or a control-shRNA. The coronary artery (CA), pulmonary artery (PA), and mesenteric artery (MA) were isolated from rats, and isometric tension measurements of arteries were performed. Compared with Sham rats, the plasma salusin-β, leptin and visfatin levels and the salusin-β protein expression levels of CA, PA, and MA were increased, while the acetylcholine- (ACh-) induced endothelium-dependent vascular relaxation of CA, PA, and MA was attenuated significantly in CHF rats and was improved significantly by salusin-β gene knockdown. Salusin-β knockdown also improved cardiac function and vascular and myocardial remodeling, increased endothelial nitric oxide synthase (eNOS) activity and nitric oxide (NO) levels, and decreased NAD(P)H oxidase activity, NOX-2 and NOX-4 expression, and reactive oxygen species (ROS) levels in arteries in CHF rats. The effects of salusin-β knockdown in CHF rats were attenuated significantly by pretreatment with the NOS inhibitor L-NAME. These results indicate that silencing salusin-β contributes to the improvement of endothelial function, cardiac function, and cardiovascular remodeling in CHF by inhibiting NAD(P)H oxidase-ROS generation and activating eNOS-NO production.

Relaxin increased blood pressure and sympathetic activity in paraventricular nucleus of hypertensive rats via enhancing oxidative stress

Relaxin, an ovarian polypeptide hormone, is found in the hypothalamic paraventricular nucleus (PVN) which is an important central integrative site for the control of blood pressure and sympathetic outflow. The aim of this study was to determine if superoxide anions modulate the effects of relaxin in the PVN. Experiments were performed in normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Relaxin mRNA and protein, and its receptor, relaxin family peptide receptor 1 (RXFP1) levels in PVN were 3.24, 3.17, and 3.64 times higher in SHRs than in WKY rats, respectively. Microinjection of relaxin-2 into the PVN dose-dependently increased mean arterial pressure (MAP), renal sympathetic nerve activity (RSNA) and heart rate (HR) in both WKY rats and SHRs, although the effects on MAP (16.87 ± 1.99 vs. 8.97 ± 1.48 mm Hg in 100 nmol), RSNA (22.60 ± 2.15 vs. 11.77 ± 1.43 % in 100 nmol) and HR (22.85 ± 3.13 vs. 12.62 ± 2.83 beats/min in 100 nmol) were greater in SHRs. Oxidative stress level was enhanced after relaxin-2 microinjection into the PVN. Pretreatment with superoxide anion scavengers or NADPH oxidase inhibitor blocked, and superoxide dismutase inhibitor potentiated the effects of relaxin-2 on MAP, RSNA and HR. RXFP1 knockdown significantly attenuated the blood pressure of SHRs, and inhibited the increases of atrial natriuretic peptide, brain natriuretic peptide, collagen I, collagen III and fibronectin in the heart of SHRs. These results demonstrated that relaxin is expressed in the PVN, and contributes to hypertension and sympathetic overdrive via oxidative stress. Down-regulation of RXFP1 in the PVN could attenuate hypertension and cardiac remodeling.

Improvement of Vascular Function by Knockdown of Salusin-β in Hypertensive Rats via Nitric Oxide and Reactive Oxygen Species Signaling Pathway

Purpose

Salusin-β, a multifunctional vasoactive peptide, has a potentially important function in the pathological development of hypertension. However, the exact functional role of salusin-β and the underlying mechanism in this process are still not fully understood. The current study aimed to investigate the effects of silencing salusin-β on vascular function and vascular remodeling, as well as its signaling pathways in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY).

Methods

Silencing salusin-β was performed by caudal vein injection of adenovirus expressing salusin-β short hairpin RNA (shRNA). Acetylcholine (ACh)-induced endothelium-dependent relaxation was used to evaluate vasodilator function, and high K⁺ solution-induced constriction was used to evaluate vasoconstriction function.

Results

Salusin-β levels in plasma and its protein expression in mesenteric artery (MA), coronary artery (CA), and pulmonary artery (PA) of SHR were higher than those in WKY. The salusin-β level and expression were decreased effectively by salusin-β shRNA. Knockdown of salusin-β decreased arterial blood pressure (ABP) and high K⁺ solution-induced vascular constrictions, and improved the endothelium-dependent relaxation and vascular remodeling in SHR. The improved effect of silencing salusin-β on ACh-induced relaxation in SHR was almost blocked by the nitric oxide synthase (NOS) inhibitor L-NAME. Compared to WKY, the endothelial NOS (eNOS) activity and level, and nitric oxide (NO) level were decreased, while NAD(P)H oxidase activity and reactive oxygen species (ROS) levels in MA, CA, and PA of SHR were increased, which were all redressed by salusin-β knockdown.

Conclusion

These results indicate that knockdown of salusin-β improves endothelium-dependent vascular relaxation and vascular remodeling and decreases ABP and vasoconstriction in SHR, which might be accomplished by increasing eNOS activation and NO release while inhibiting NAD(P)H oxidase derived-ROS generation. Scavenging salusin-β improves vascular function and then prevents the development and progression of vasculopathy of hypertension.

Influence of irisin on diet-induced metabolic syndrome in experimental rat model

OBJECTIVE

To evaluate the influence of irisin on the experimental paradigm of non-alcoholic fatty liver (NAFL) as a part of MetS cluster.

METHODS

Forty male albino rats were divided into four groups; normal control, standard diet + irisin, high carbohydrate and fat diet (HCHF), and HCHF + irisin. After the experimental period, levels of fasting blood sugar (FBS), insulin, lipid profile, kidney functions, salusin-alpha (Sal-α), adropin, and retinol-binding protein-4 (RBP-4) were evaluated. Peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1α) expression in skeletal muscle was evaluated by quantitative real-time PCR. Aorta, liver, pancreas, and skeletal muscle tissue samples were prepared for histopathological examination.

RESULTS

Rats administrated HCHF showed elevated levels of FBS, lipid profile, kidney functions, RBP-4, and downregulation of PGC-1α expression along with a decline in levels of insulin, Sal-α, and adropin while administration of irisin significantly attenuated these levels.

CONCLUSIONS

Irisin as based therapy could emerge as a new line of treatment against MetS and its related diseases.

Assessment of salusin alpha and salusin beta levels in patients with newly diagnosed dipper and non-dipper hypertension

OBJECTIVE

The pathophysiology of non-dipper hypertension has not been clarified. The relationship between salusins with atherosclerosis and hypertension has gained attention in recent years. The aim of this paper is to investigate whether salusins are associated with circadian blood pressure, left ventricular mass index, and diastolic functions in newly diagnosed hypertensives.

METHODS

The study included 88 newly diagnosed hypertensive individuals. Twenty-four-hour ambulatory blood pressure monitoring and echocardiographic examinations were performed. The patients were assigned to dipper hypertension (n = 41) and non-dipper hypertension (n = 47) groups based on the ambulatory blood pressure monitoring results according to the presence of ≥ a 10% decrease in nighttime blood pressure values or not. Serum salusin α and β levels were determined by electrochemiluminescence immunological test method.

RESULTS

Compared to dipper hypertension, non-dipper hypertension group demonstrated lower salusin α levels (1818.71 ± 221.67 vs 1963 ± 200.75 pg/mL, p = .002), mitral E/A, septal E'/A' and higher salusin β levels (576.24 ± 68.15 vs 516.13 ± 90.7 pg/ml, p = .001) and left ventricular mass index. Multivariate logistic regression analysis revealed salusin-α (OR 0.474, 95% CI 0.262 to 0.986, p = .001), salusin-β (OR 2.550, 95% CI 2.123 to 2.991, p = .018), and left ventricular mass index (OR 2.620, 95% CI 2.124 to 2.860, p = .011) as independent predictors of non-dipper hypertension. As candidate markers to predict non-dipper hypertension, decreased salusin α, and increased salusin β levels may mediate crosstalk between sympathetic and parasympathetic systems and indicate poor cardiovascular prognosis in hypertension.

A TOR2A Gene Product: Salusin-β Contributes to Attenuated Vasodilatation of Spontaneously Hypertensive Rats

PURPOSE

Attenuated vasodilatation of small arteries is a hallmark feature of hypertension. Salusin-β, which is a TOR2A gene product and an important vasoactive peptide, has a close relationship with cardiovascular disease. This study aimed to determinate the roles of salusin-β in vasodilatation, and its signal pathways in Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR).

METHODS

Isometric tension experiments were performed. Vasodilatation was induced by acetylcholine (ACh) or sodium nitroprusside (SNP).

RESULTS

Plasma salusin-β levels and their protein expressions in coronary artery (CA), mesenteric artery (MA), and pulmonary artery (PA) of SHR were much higher than that of WKY. Intravenous injection of salusin-β increased arterial blood pressure in SHR, while anti-salusin-β IgG decreased it. Salusin-β further deteriorated, while anti-salusin-β IgG improved, the attenuated ACh-induced relaxation, the decreased nitric oxide (NO) level, and endothelial nitric oxide synthase (eNOS) activity in arteries of SHR, and salusin-β had no significant effect on SNP-induced relaxation. The NAD(P)H oxidase activity and reactive oxygen species (ROS) level in arteries of SHR were much higher than that of WKY, which was further increased by salusin-β but reduced by anti-salusin-β IgG. ROS scavenger NAC or antioxidant apocynin significantly inhibited, while SOD inhibitor DETC aggravated, the effects of salusin-β, and the eNOS inhibitor L-NAME inhibited the effects of anti-salusin-β IgG.

CONCLUSIONS

These results indicated that enhanced salusin-β activity is involved in attenuated endothelium-dependent vasodilatation pathogenesis in SHR by activating NAD(P)H oxidase derived ROS generation and inhibiting eNOS activation and NO release.

Salusin-β mediates tubular cell apoptosis in acute kidney injury: Involvement of the PKC/ROS signaling pathway

Salusin-β is abundantly expressed in many organs and tissues including heart, blood vessels, brain and kidneys. Recent studies have identified salusin-β as a bioactive peptide that contributes to various diseases, such as atherosclerosis, hypertension, diabetes and metabolic syndrome. However, the role of salusin-β in the pathogenesis of acute kidney injury (AKI) is largely unclear. In the present study, we investigated the roles of salusin-β in cisplatin or lipopolysaccharide (LPS)-induced renal injury. Herein, we found that salusin-β expression was upregulated in both renal tubular cells and kidney tissues induced by both cisplatin and LPS. In vitro, silencing of salusin-β diminished, whereas overexpression of salusin-β exaggerated the increased PKC phosphorylation, oxidative stress, histone γH2AX expression, p53 activation and apoptosis in either cisplatin or LPS-challenged renal tubular cells. More importantly, salusin-β overexpression-induced tubular cell apoptosis were abolished by using the PKC inhibitor Go 6976, reactive oxygen species (ROS) scavenger NAC, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin (Apo) or p53 inhibitor Pifithrin-α. In animals, blockade of salusin-β alleviated PKC phosphorylation, ROS accumulation, DNA damage, and p53 activation as well as renal dysfunction in mice after administration of cisplatin or LPS. Taken together, these results suggest that overexpressed salusin-β is deleterious in AKI by activation of the PKC/ROS signaling pathway, thereby priming renal tubular cells for apoptosis and death.

Exacerbated pressor and sympathoexcitatory effects of central Elabela in spontaneously hypertensive rats

Elabela (ELA) is a newly discovered peptide that acts as a novel endogenous ligand of angiotensin receptor-like 1 (APJ) receptor. This study was designed to evaluate the effects of ELA-21 in paraventricular nucleus (PVN) on blood pressure and sympathetic nerve activity in spontaneously hypertensive rats (SHR). Experiments were performed in male Wistar-Kyoto rats (WKY) and SHR. ELA expression was upregulated in PVN of SHR. PVN microinjection of ELA-21 increased renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), plasma norepinephrine, and arginine vasopressin (AVP) levels in SHR. Intravenous injection of ELA-21 significantly decreased MAP and HR in both WKY and SHR, but only induced a slight decrease in RSNA. APJ antagonist F13A in PVN abolished the effects of ELA-21 on RSNA, MAP and HR. Intravenous infusion of both ganglionic blocker hexamethonium and AVP V1a receptor antagonist SR49059 caused significant reduction in the effects of ELA-21 on RSNA, MAP and HR in SHR, while combined administration of hexamethonium and SR49059 abolished the effects of ELA-21. ELA-21 microinjection stimulated Akt and p85α subunit of phosphatidylinositol 3-kinase (PI3K) phosphorylation in PVN, whereas PI3K inhibitor LY294002 or Akt inhibitor MK-2206 almost abolished the effects of ELA-21 on RSNA, MAP, and HR. Chronic PVN infusion of ELA-21 induced sympathetic activation, hypertension, and AVP release accompanied with cardiovascular remodeling in normotensive WKY. In conclusion, ELA-21 in PVN induces exacerbated pressor and sympathoexcitatory effects in hypertensive rats via PI3K-Akt pathway.NEW & NOTEWORTHY We demonstrated that PVN microinjection of ELA-21 increases sympathetic nerve activity and blood pressure, which can be abolished by pretreatment of APJ antagonist. This is the first demonstration that central ELA can induce hypertension. The pressor effects in PVN are mediated by both sympathetic activation and vasopressin release via PI3K-Akt pathway. Our data confirm that ELA is upregulated in the PVN of SHR and so may be involved in the pressor and sympathoexcitatory effects in hypertension.

Silencing salusin β ameliorates heart failure in aged spontaneously hypertensive rats by ROS-relative MAPK/NF-κB pathways in the paraventricular nucleus

OBJECTIVE

Sustained hypertension is a major cause of heart failure in aging hypertensive patients. Salusin β, a novel bioactive peptide of 20 amino acids, has been reported to participate in various cardiovascular diseases, including hypertension. We therefore hypothesized that central knockdown of salusin β might be effective for hypertension-induced heart failure treatment.

METHODS AND RESULTS

Eighteen-month-old male aged spontaneously hypertensive rats (SHR) with heart failure and WKY rats were microinjected with either a specific adenoviral vector encoding salusin β shRNA (Ad-Sal-shRNA) or a scramble shRNA (Ad-Scr-shRNA) in the hypothalamic paraventricular nucleus (PVN) for 4 weeks. Radiotelemetry and echocardiography were used for measuring blood pressure and cardiac function, respectively. Blood samples and heart were harvested for evaluating plasma norepinephrine, tyrosine hydroxylase, and cardiac morphology, respectively. The mesenteric arteries were separated for measurement of vascular responses. The PVN was analyzed for salusin β, proinflammatory cytokines (PICs), mitogen-activated protein kinase (MAPK), NF-κB, and reactive oxygen species (ROS) levels. Compared with normotensive rats, aging SHR with heart failure had dramatically increased salusin β expression. Silencing salusin β with Ad-Sal-shRNA attenuated arterial pressure and improved autonomic function, cardiac and vascular dysfunction in aging SHR with heart failure, but not in aging WKY rats. Knockdown of salusin β significantly reduced paraventricular nucleus PICs levels, MAPK and NF-κB activity, and ROS levels in aging SHR with heart failure.

CONCLUSION

These data demonstrate that in aging SHR, the heart failure that was developed during the end stage of hypertension could be ameliorated by silencing salusin β.

Relationship of salusin-alpha and salusin-beta levels with atherosclerosis in patients undergoing haemodialysis

INTRODUCTION

In patients undergoing haemodialysis, cardiovascular mortality and morbidity, characterised by accelerated atherosclerosis and increased inflammation, are elevated. Salusins are newly defined molecules in the atherosclerotic processes, and while salusin-alpha (Sal-α) acts as an antiatherogenic factor, salusin-beta (Sal-β) has a proatherogenic role. Their roles are as yet undefined in patients undergoing haemodialysis.

METHODS

In this cross-sectional study, salusin levels, carotid intima-media thickness (CIMT) from the common carotid artery and pulse wave velocity (PWV) were measured for 180 patients undergoing haemodialysis and 90 healthy controls.

RESULTS

Mean Sal-α and Sal-β levels in patients undergoing haemodialysis (Sal-α: 726.4 ± 578.7 pg/mL; Sal-β: 1,080.4 ± 757.1 pg/mL) and healthy controls (Sal-α: 325.8 ± 303.7 pg/mL; Sal-β: 268.1 ± 409.0 pg/mL) were determined. Negative correlation was observed between Sal-α levels and CIMT (patients undergoing haemodialysis: r = -0.330, p < 0.0001; healthy controls: r = -0.223, p = 0.035) and PWV (patients undergoing haemodialysis: r = -0.210, p = 0.005; healthy controls: r = -0.378, p < 0.0001) in both groups. In patients undergoing haemodialysis, positive correlation was observed between Sal-β/Sal-α ratio and CIMT (r = 0.190, p = 0.012) and PWV (r = 0.155, p = 0.041). On subgroup analysis, Sal-α levels were found to be low in patients with diabetes mellitus.

CONCLUSION

Patients undergoing haemodialysis have higher Sal-β and Sal-α levels, and their higher Sal-β/Sal-α ratio, in comparison with healthy controls, might have cardiovascular risk implications.

Exogenous Pancreatic Kallikrein Improves Diabetic Cardiomyopathy in Streptozotocin-Induced Diabetes

Aims: To evaluate the protective effects of exogenous pancreatic kallikrein (PKK) treatment on diabetic cardiomyopathy (DCM) and explore the underlying mechanisms. Methods and Results: Streptozotocin (STZ)-induced diabetic rats, a type 1 diabetic model, were treated with either PKK or saline for 12 weeks. Non-diabetic rats were used as controls. PKK administration attenuated the mitochondria swelling, Z line misalignments, myofibrosis and interstitial collagen accumulation in diabetic myocardial tissue. The oxidative stress imbalance including increased nitrotyrosine, decreased anti-oxidative components such as nuclear receptor nuclear factor like 2 (Nrf2), glutathione peroxidase 1(GPx-1), catalase (CAT) and superoxide dismutase (SOD), were recovered in the heart of PKK-treated diabetic rats. In diabetic rats, protein expression of TGF-β1 and accumulation of collagen I in the heart tissues was decreased after PKK administration. Markers for inflammation were decreased in diabetic rats by PKK treatment. Compared to diabetic rats, PKK reversed the degradation of IκB-α, an inhibitive element of heterotrimer nuclear factor kappa B (NF-κB). The endothelial nitric oxide synthase (eNOS) protein and myocardial nitrate/nitrite were impaired in the heart of diabetic rats, which, however, were restored after PKK treatment. The sarcoplasmic reticulum Ca²⁺-ATPase 2 (SERCA2) and phospholamban (PLN) were mishandled in diabetic rats, while were rectified in PKK-treated diabetic rats. The plasma NT-proBNP level was increased in diabetic rats while was reduced with PKK treatment. Conclusion: PKK protects against DCM via reducing fibrosis, inflammation, and oxidative stress, promoting nitric oxide production, as well as restoring the function of the calcium channel.

Alamandine injected into the paraventricular nucleus increases blood pressure and sympathetic activation in spontaneously hypertensive rats

Alamandine is a newly discovered new component of the renin-angiotensin (Ang) system (RAS) that has been shown to exert vasoactive effects in some areas of the nervous system. The present study investigated whether administration of alamandine to the hypothalamic paraventricular nucleus (PVN) modulates blood pressure and sympathetic activity. Mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were recorded in anaesthetized rats. PVN microinjection of alamandine increased MAP and RSNA both in Wistar-Kyoto (WKY) rats and in spontaneously hypertensive rats (SHRs), but to a greater extent in SHRs. Moreover, these effects were blocked by pretreatment with alamandine receptor Mas-related G-protein-coupled receptor, member D (MrgD) antagonist D-Pro⁷-Ang-(1-7), adenylyl cyclase (AC) inhibitor SQ22536, and protein kinase A (PKA) inhibitor rp-adenosine-3',5'-cyclic monophosphorothionate (Rp-cAMP). Treatment with D-Pro⁷-Ang-(1-7), SQ22536, or Rp-cAMP alone in PVN decreased MAP and RSNA in the SHRs. Conversely cAMP alone increased MAP and RSNA, and pretreatment with cAMP enhanced alamandine's effects. These results indicate that microinjection of alamandine into the PVN increases blood pressure and sympathetic outflow via MrgD and the cAMP-PKA pathway.

Salusin-β Is Involved in Diabetes Mellitus-Induced Endothelial Dysfunction via Degradation of Peroxisome Proliferator-Activated Receptor Gamma

The pathophysiological mechanisms for vascular lesions in diabetes mellitus (DM) are complex, among which endothelial dysfunction plays a vital role. Therapeutic target against endothelial injury may provide critical venues for treatment of diabetic vascular diseases. We recently identified that salusin-β contributed to high glucose-induced endothelial cell apoptosis. However, the roles of salusin-β in DM-induced endothelial dysfunction remain largely elusive. Male C57BL/6J mice were used to induce type 2 diabetes mellitus (T2DM) model. Human umbilical vein endothelial cells (HUVECs) were cultured in high glucose/high fat (HG/HF) medium. We demonstrated increased expression of salusin-β in diabetic aortic tissues and high-glucose/high-fat- (HG/HF-) incubated HUVECs. Disruption of salusin-β by shRNA abrogated the reactive oxygen species (ROS) production, inflammation, and nitrotyrosine content of HUVECs cultured in HG/HF medium. The HG/HF-mediated decrease in peroxisome proliferator-activated receptor γ (PPARγ) expression was restored by salusin-β shRNA, and PPARγ inhibitor T0070907 abolished the protective actions of salusin-β shRNA on endothelial injury in HG/HF-treated HUVECs. Salusin-β silencing obviously improved endothelium-dependent vasorelaxation, oxidative stress, inflammatory response, and nitrative stress in diabetic aorta. Taken together, our results highlighted the essential role of salusin-β in pathological endothelial dysfunction, and salusin-β may be a promising target in treatment of vascular complications of DM.

Vaccarin alleviates hypertension and nephropathy in renovascular hypertensive rats

The kidney is an important organ in the regulation of blood pressure, and it is also one of the primary target organs of hypertension. Kidney damage in response to hypertension eventually leads to renal insufficiency. The authors previously demonstrated that vaccarin exhibits a protective role in endothelial injury. However, the effects of vaccarin on the two-kidney, one clip (2K1C) renovascular hypertension model and subsequent kidney injury have yet to be fully elucidated. The present study was designed to investigate the roles and mechanisms of vaccarin in attenuating hypertension and whether vaccarin had beneficial effects on kidney injury. The 2K1C rats had greater fibrosis, apoptosis, reactive oxygen species production, inflammation, angiotensin II (Ang II) and angiotensin type 1 (AT1) receptors in the right kidney compared with normotensive rats, which were alleviated by a high dose of vaccarin and captopril. Vaccarin treatment attenuated hypertension, reduced fibrosis markers, NADPH oxidase (NOX)-2, NOX-4, 3-nitrotyrosine, tumor necrosis factor-α, interleukin 1β (IL-1β), and IL-6 protein levels and altered pro-apoptotic protein levels including caspase-3, anti-apoptosis protein B cell lymphoma (Bcl)-2 and Bcl-2 associated X, apoptosis regulator in the right kidney of 2K1C rats. These findings suggest that the protective effects of vaccarin on the right kidney in renovascular hypertension are possibly due to downregulation of fibrosis, inflammatory molecules, oxidative stress, Ang II, and AT1 receptor levels.

Vaccarin administration ameliorates hypertension and cardiovascular remodeling in renovascular hypertensive rats

Sympathetic overdrive, activation of renin angiotensin systems (RAS), and oxidative stress are vitally involved in the pathogenesis of hypertension and cardiovascular remodeling. We recently identified that vaccarin protected endothelial cell function from oxidative stress or high glucose. In this study, we aimed to investigate whether vaccarin attenuated hypertension and cardiovascular remodeling. Two-kidney one-clip (2K1C) model rats were used, and low dose of vaccarin (10 mg/kg), high dose of vaccarin (30 mg/kg), captopril (30 mg/kg) were intraperitoneally administrated. Herein, we showed that 2K1C rats exhibited higher systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), left ventricular mass/body weight ratio, myocardial hypertrophy or fibrosis, media thickness, and media thickness to lumen diameter, which were obviously alleviated by vaccarin and captopril. In addition, both vaccarin and captopril abrogated the increased plasma renin, angiotensin II (Ang II), norepinephrine (NE), and the basal sympathetic activity. The AT1R protein expressions, NADPH oxidase subunit NOX-2 protein levels and malondialdehyde (MDA) content were significantly increased, whereas superoxide dismutase (SOD) and catalase (CAT) activities were decreased in myocardium, aorta, and mesenteric artery of 2K1C rats, both vaccarin and captopril treatment counteracted these changes in renovascular hypertensive rats. Collectively, we concluded that vaccarin may be a novel complementary therapeutic medicine for the prevention and treatment of hypertension. The mechanisms for antihypertensive effects of vaccarin may be associated with inhibition of sympathetic activity, RAS, and oxidative stress.

The Frequency-Dependent Aerobic Exercise Effects of Hypothalamic GABAergic Expression and Cardiovascular Functions in Aged Rats

A decline in cardiovascular modulation is a feature of the normal aging process and associated with cardiovascular diseases (CVDs) such as hypertension and stroke. Exercise training is known to promote cardiovascular adaptation in young animals and positive effects on motor and cognitive capabilities, as well as on brain plasticity for all ages in mice. Here, we examine the question of whether aerobic exercise interventions may impact the GABAergic neurons of the paraventricular nucleus (PVN) in aged rats which have been observed to have a decline in cardiovascular integration function. In the present study, young (2 months) and old (24 months) male Wistar rats were divided into young control (YC), old sedentary, old low frequency exercise (20 m/min, 60 min/day, 3 days/week, 12 weeks) and old high frequency exercise (20 m/min, 60 min/day, 5 days/week, 12 weeks). Exercise training indexes were obtained, including resting heart rate (HR), blood pressure (BP), plasma norepinephrine (NE), and heart weight (HW)-to-body weight (BW) ratios. The brain was removed and processed according to the immunofluorescence staining and western blot used to analyze the GABAergic terminal density, the proteins of GAD67, GABA_A receptor and gephyrin in the PVN. There were significant changes in aged rats compared with those in the YC. Twelve weeks aerobic exercise training has volume-dependent ameliorated effects on cardiovascular parameters, autonomic nervous activities and GABAergic system functions. These data suggest that the density of GABAergic declines in the PVN is associated with imbalance in autonomic nervous activities in normal aging. Additionally, aerobic exercise can rescue aging-related an overactivity of the sympathetic nervous system and induces modifications the resting BP and HR to lower values via improving the GABAergic system in the PVN.

Silencing salusin-β attenuates cardiovascular remodeling and hypertension in spontaneously hypertensive rats

Salusin-β is a bioactive peptide involved in vascular smooth muscle cell proliferation, vascular fibrosis and hypertension. The present study was designed to determine the effects of silencing salusin-β on hypertension and cardiovascular remodeling in spontaneously hypertensive rats (SHR). Thirteen-week-old male SHR and normotensive Wistar-Kyoto rats (WKY) were subjected to intravenous injection of PBS, adenoviral vectors encoding salusin-β shRNA (Ad-Sal-shRNA) or a scramble shRNA. Salusin-β levels in plasma, myocardium and mesenteric artery were increased in SHR. Silencing salusin-β had no significant effect on blood pressure in WKY, but reduced blood pressure in SHR. It reduced the ratio of left ventricle weight to body weight, cross-sectional areas of cardiocytes and perivascular fibrosis, and decreased the media thickness and the media/lumen ratio of arteries in SHR. Silencing salusin-β almost normalized plasma norepinephrine and angiotensin II levels in SHR. It prevented the upregulation of angiotensin II and AT₁ receptors, and reduced the NAD(P)H oxidase activity and superoxide anion levels in myocardium and mesenteric artery of SHR. Knockdown of salusin-β attenuated cell proliferation and fibrosis in vascular smooth muscle cells from SHR. These results indicate that silencing salusin-β attenuates hypertension and cardiovascular remodeling in SHR.

Renal sympathetic denervation attenuates hypertension and vascular remodeling in renovascular hypertensive rats

Li P, Huang P, Yang Y, Liu C, Lu Y, Wang F, Sun W, Kong X. Renal sympathetic denervation attenuates hypertension and vascular remodeling in renovascular hypertensive rats. J Appl Physiol 122: 121–129, 2017. First published October 14, 2016; doi: 10.1152/japplphysiol.01019.2015 .—Sympathetic activity is enhanced in patients with essential or secondary hypertension, as well as in various hypertensive animal models. Therapeutic targeting of sympathetic activation is considered an effective antihypertensive strategy. We hypothesized that renal sympathetic denervation (RSD) attenuates hypertension and improves vascular remodeling and renal disease in the 2-kidney, 1-clip (2K1C) rat model. Rats underwent 2K1C modeling or sham surgery; then rats underwent RSD or sham surgery 4 wk later, thus resulting in four groups (normotensive-sham, normotensive-RSD, 2K1C-sham, and 2K1C-RSD). Norepinephrine was measured by ELISA. Echocardiography was used to assess heart function. Fibrosis and apoptosis were assessed by Masson and TUNEL staining. Changes in mean arterial blood pressure in response to hexamethonium and plasma norepinephrine levels were used to evaluate basal sympathetic nerve activity. The 2K1C modeling success rate was 86.8%. RSD reversed the elevated systolic blood pressure induced by 2K1C, but had no effect on body weight. Compared with rats in the 2K1C-sham group, rats in the 2K1C-RSD group showed lower left ventricular mass/body weight ratio, interventricular septal thickness in diastole, left ventricular end-systolic diameter, and left ventricular posterior wall thickness in systole, whereas fractional shortening and ejection fraction were higher. Right kidney apoptosis and left kidney hypertrophy were not changed by RSD. Arterial fibrosis was lower in animals in the 2K1C-RSD group compared with those in the 2K1C-sham group. RSD reduced plasma norepinephrine and basal sympathetic activity in rats in the 2K1C-RSD group compared with rats in the 2K1C-sham group. These results suggest a possible clinical efficacy of RSD for renovascular hypertension.

NEW & NOTEWORTHY The effects of renal sympathetic denervation (RSD) on hypertension, cardiac function, vascular fibrosis, and renal apoptosis were studied in the 2K1C rat model. Results showed that RSD attenuated hypertension, improved vascular remodeling, and reduced vascular fibrosis through decreased sympathetic activity in the 2K1C rat model, but it did not change the kidney size, renal apoptosis, or renal caspase-3 expression. These results could suggest possible clinical efficacy of RSD for renovascular hypertension.

Exercise training attenuates renovascular hypertension partly via RAS- ROS- glutamate pathway in the hypothalamic paraventricular nucleus

Exercise training (ExT) has been reported to benefit hypertension; however, the exact mechanisms involved are unclear. We hypothesized that ExT attenuates hypertension, in part, through the renin-angiotensin system (RAS), reactive oxygen species (ROS), and glutamate in the paraventricular nucleus (PVN). Two-kidney, one-clip (2K1C) renovascular hypertensive rats were assigned to sedentary (Sed) or treadmill running groups for eight weeks. Dizocilpine (MK801), a glutamate receptor blocker, or losartan (Los), an angiotensin II type1 receptor (AT1-R) blocker, were microinjected into the PVN at the end of the experiment. We found that 2K1C rats had higher mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). These rats also had excessive oxidative stress and overactivated RAS in PVN. Eight weeks of ExT significantly decreased MAP and RSNA in 2K1C hypertensive rats. ExT inhibited angiotensin-converting enzyme (ACE), AT1-R, and glutamate in the PVN, and angiotensin II (ANG II) in the plasma. Moreover, ExT attenuated ROS by augmenting copper/zinc superoxide dismutase (Cu/Zn-SOD) and decreasing p^47phox and gp^91phox in the PVN. MK801or Los significantly decreased blood pressure in rats. Together, these findings suggest that the beneficial effects of ExT on renovascular hypertension may be, in part, through the RAS-ROS-glutamate pathway in the PVN.

Acupuncture Decreases Blood Pressure Related to Hypothalamus Functional Connectivity with Frontal Lobe, Cerebellum, and Insula: A Study of Instantaneous and Short-Term Acupuncture Treatment in Essential Hypertension

The therapeutic effects of acupuncture in decreasing blood pressure are ambiguous and underlying acupuncture in hypertension treatment has not been investigated. Our objective was to observe the change of quality of life and compare the differences in brain functional connectivity by investigating instantaneous and short-term acupuncture treatment in essential hypertension patients. A total of 30 patients were randomly divided into the LR3 group and sham acupoint group. Subjects received resting-state fMRI among preacupuncture, postinstantaneous, and short-term acupuncture treatment in two groups. Hypothalamus was selected as the seed point to analyze the changes in connectivity. We found three kinds of results: (1) There was statistical difference in systolic blood pressure in LR3 group after the short-term treatment and before acupuncture. (2) Compared with sham acupoint, acupuncture at LR3 instantaneous effects in the functional connectivity with seed points was more concentrated in the frontal lobe. (3) Compared with instantaneous effects, acupuncture LR3 short-term effects in the functional connectivity with seed points had more regions in frontal lobe, cerebellum, and insula. These brain areas constituted a neural network structure with specific functions that could explain the mechanism of therapy in hypertension patients by LR3 acupoint.

Salusin-β Promotes Vascular Smooth Muscle Cell Migration and Intimal Hyperplasia After Vascular Injury via ROS/NFκB/MMP-9 Pathway

AIMS

Media-to-intima migration of vascular smooth muscle cells (VSMCs) is critical to intimal thickening in atherosclerosis and restenosis after coronary angioplasty. The aim of this study is to determine the effects of salusin-β on VSMC migration and intimal hyperplasia after vascular injury and the underlying mechanism.

RESULTS

In vitro, salusin-β promoted VSMC migration, which was attenuated by matrix metalloproteinase (MMP)-9 inhibition. Inhibition or knockdown of p65-nuclear factor kappa beta (NFκB) in VSMCs suppressed salusin-β-induced MMP-9 expression and VSMC migration. Salusin-β increased NADPH oxidase 2 (NOX2) expression and reactive oxygen species (ROS) production, which were prevented by NOX2-small interfering RNA (siRNA) transfection. Salusin-β-induced p65-NFκB translocation, MMP-9 expression, and VSMC migration were inhibited by ROS scavenger, NADPH oxidase inhibitor, or NOX2-siRNA. In vivo, carotid artery ligation-induced vascular injury resulted in intimal hyperplasia in injured artery in rats. Salusin-β was upregulated in the injured carotid arteries of rats, which was attributed to reduced miR-133a-3p expression. Knockdown of salusin-β with siRNA attenuated the vascular injury-induced intimal thickening, p65-NFκB nuclear translocation, and NOX2 and MMP-9 expressions in rats.

INNOVATION

Salusin-β is a critical modulator in VSMC migration and neointima formation in response to vascular injury.

CONCLUSIONS

Salusin-β promotes VSMC migration and vascular injury-induced intimal hyperplasia via MMP-9 accumulation due to NOX2 activation, followed by ROS production, IκBα phosphorylation and degradation, and p65-NFκB translocation. We propose that salusin-β may be important in the VSMC migration and neointima of some vascular diseases. Antioxid. Redox Signal. 24, 1045-1057.

Salusin-β induces foam cell formation and monocyte adhesion in human vascular smooth muscle cells via miR155/NOX2/NFκB pathway

Vascular smooth muscle cells (VSMCs) are indispensible components in foam cell formation. Salusin-β is a stimulator in the progression of atherosclerosis. Here, we showed that salusin-β increased foam cell formation evidenced by accumulation of lipid droplets and intracellular cholesterol content, and promoted monocyte adhesion in human VSMCs. Salusin-β increased the expressions and activity of acyl coenzyme A:cholesterol acyltransferase-1 (ACAT-1) and vascular cell adhesion molecule-1 (VCAM-1) in VSMCs. Silencing of ACAT-1 abolished the salusin-β-induced lipid accumulation, and silencing of VCAM-1 prevented the salusin-β-induced monocyte adhesion in VSMCs. Salusin-β caused p65-NFκB nuclear translocation and increased p65 occupancy at the ACAT-1 and VCAM-1 promoter. Inhibition of NFκB with Bay 11-7082 prevented the salusin-β-induced ACAT-1 and VCAM-1 upregulation, foam cell formation and monocyte adhesion in VSMCs. Scavenging ROS, inhibiting NADPH oxidase or knockdown of NOX2 abolished the effects of salusin-β on ACAT-1 and VCAM-1 expressions, p65-NFκB nuclear translocation, lipid accumulation and monocyte adhesion in VSMCs. Salusin-β increased miR155 expression, and knockdown of miR155 prevented the effects of salusin-β on ACAT-1 and VCAM-1 expressions, p65-NFκB nuclear translocation, lipid accumulation, monocyte adhesion and ROS production in VSMCs. These results indicate that salusin-β induces foam formation and monocyte adhesion via miR155/NOX2/NFκB-mediated ACAT-1 and VCAM-1 expressions in VSMCs.

Renal Sympathetic Denervation Improves Cardiac Dysfunction in Rats With Chronic Pressure Overload

Varied causative and risk factors can lead to cardiac dysfunction. Cardiac dysfunction often evolves into heart failure by cardiac remodeling due to autonomic nervous system disturbance and neurohumoral abnormalities, even if the detriment factors are removed. Renal sympathetic nerve activity plays a pivotal regulatory role in neurohumoral mechanisms. The present study was designed to determine the therapeutic effects of renal sympathetic denervation (RSD) on cardiac dysfunction, fibrosis, and neurohumoral response in transverse aortic constriction (TAC) rats with chronic pressure overload. The present study demonstrated that RSD attenuated myocardial fibrosis and hypertrophy, and structural remodeling of the left atrium and ventricle, up-regulated cardiac β adrenoceptor (β-AR, including β1AR and β2AR) and sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) while down-regulated angiotensin II type 1 receptor (AT1R), and decreased plasma B-type natriuretic peptide (BNP), norepinephrine (NE), angiotensin II (Ang II), and arginine vasopressin (AVP) levels in TAC rats with chronic pressure overload. We conclude that RSD attenuates myocardial fibrosis, the left atrial enlargement, and the left ventricular wall hypertrophy; inhibits the overdrive of the sympathetic nervous system (SNS), renin-angiotensin-aldosterone system (RAAS), and AVP system in TAC rats with chronic pressure overload. RSD could be a promising non-pharmacological approach to control the progression of cardiac dysfunction.

Blockade of Salusin-β in Hypothalamic Paraventricular Nucleus Attenuates Hypertension and Cardiac Hypertrophy in Salt-induced Hypertensive Rats

Salusin-β, a multifunctional bioactive peptide, is considered as a promising candidate biomarker for predicting cardiovascular diseases. This study was designed to determine whether inhibition of salusin-β in the hypothalamic paraventricular nucleus (PVN) delays the progression of hypertension and attenuates cardiac hypertrophy by restoring neurotransmitters and cytokines. Male Sprague Dawley rats were fed with a normal salt diet (NS, 0.3%) or a high salt diet (HS, 8%) for 8 weeks to induce hypertension. Then, these rats received bilateral PVN infusion of a specific salusin-β blocker, antisalusin-β IgG (SIgG), or control IgG (CIgG) for 2 weeks. HS rats exhibited higher mean arterial pressure and cardiac hypertrophy as indicated by increased whole heart weight/bodyweight ratio, whole heart weight/tibia length ratio, left ventricular weight/tibia length ratio, and messenger RNA levels of cardiac atrial natriuretic peptide (ANP), and β-myosin heavy chain. Compared with NS rats, HS rats had higher levels of glutamate, norepinephrine, tyrosine hydroxylase, proinflammatory cytokines, and lower levels of gamma-aminobutyric acid, interleukin 10, and the 67-kDa isoform of glutamate decarboxylase (GAD67) in the PVN, and higher plasma levels of proinflammatory cytokines. Chronic PVN infusion of SIgG attenuated all these changes in HS rats. Our findings suggest that HS rats have an imbalance between excitatory and inhibitory neurotransmitters, as well as an imbalance between proinflammatory and anti-inflammatory cytokines in the PVN; and chronic inhibition of salusin-β in the PVN restores neurotransmitters and cytokines in the PVN, thereby attenuating hypertensive responses and cardiac hypertrophy.

Central blockade of salusin β attenuates hypertension and hypothalamic inflammation in spontaneously hypertensive rats

Salusin β is a multifunctional bioactive peptide and is considered as a promising candidate biomarker for predicting atherosclerotic cardiovascular diseases. The present study was designed to investigate the roles and mechanisms of salusin β in the paraventricular nucleus (PVN) in attenuating hypertension and hypothalamic inflammation and whether central salusin β blockade has protective effects in essential hypertension. Normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were used in this study. The rats were chronic PVN infusion either specific salusin β blocker, antisalusin β IgG (SIgG), or control IgG (CIgG) for 2 weeks. Hypertensive rats had significantly increased salusin β expression compared with normotensive rats. Central blockade of salusin β attenuated hypertension, reduced circulating norepinephrine (NE) levels, and improved cardiac hypertrophy and function in hypertensive rats. Salusin β blockade significantly reduced proinflammatory cytokines (PICs), nuclear factor-kappa B (NF-κB) activity, reactive oxygen species (ROS) levels, and altered renin-angiotensin system (RAS) components in the PVN of hypertensive rats. These findings suggest that the beneficial effects of salusin β blockade in essential hypertension are possibly due to down-regulate of inflammatory molecules and ROS in the PVN.

Salusin-β contributes to vascular remodeling associated with hypertension via promoting vascular smooth muscle cell proliferation and vascular fibrosis

Vascular smooth muscle cell (VSMC) proliferation and vascular fibrosis are closely linked with hypertension and atherosclerosis. Salusin-β is a bioactive peptide involved in the pathogenesis of atherosclerosis. However, it is still largely undefined whether salusin-β is a potential candidate in the VSMC proliferation and vascular fibrosis. Experiments were carried out in human vascular smooth muscle cells (VSMCs) and in rats with intravenous injection of lentivirus expressing salusin-β. In vitro, salusin-β promoted VSMCs proliferation, which was attenuated by adenylate cyclase inhibitor SQ22536, PKA inhibitor Rp-cAMP, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478, ERK inhibitor U0126 or cAMP response element binding protein (CREB) inhibitor KG501. It promoted the phosphorylation of ERK1/2, CREB and EGFR, which were abolished by SQ22536 or Rp-cAMP. Furthermore, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478 diminished the salusin-β-evoked ERK1/2 and CREB phosphorylation. On the other hand, salusin-β increased collagen-I, collagen-III, fibronectin and connective tissue growth factor (CTGF) mRNA and phosphorylation of Smad2/3, which were prevented by ALK5 inhibitor A83-01. In vivo, salusin-β overexpression increased the media thickness, media/lumen ratio coupled with ERK1/2, CREB, EGFR and Smad2/3 phosphorylation, as well as the mRNA of collagen-I, collagen-III, fibronectin, transforming growth factor-β1 (TGF-β1) and CTGF in arteries. Moreover, salusin-β overexpression in rats caused severe hypertension. Intravenous injection of salusin-β dose-relatedly increased blood pressure, but excessive salusin-β decreased blood pressure and heart rate. These results indicate that salusin-β promotes VSMC proliferation via cAMP-PKA-EGFR-CREB/ERK pathway and vascular fibrosis via TGF-β1-Smad pathway. Increased salusin-β contributes to vascular remodeling and hypertension.

Is the serum level of salusin-β associated with hypertension and atherosclerosis in the pediatric population?

BACKGROUND

Salusins are recently identified endogenous bioactive peptides that have hypotensive and bradycardiac effects. Salusin-β is involved in the pathogenesis of human atherosclerosis.

METHODS

This was a prospective cohort study of a young patient population with hypertension (HTN). Based on ambulatory blood pressure monitoring (ABPM), the adolescents were categorized into two groups, namely, a hypertensive group consisting of patients with essential (primary) HTN (HTN group) and a group consisting of patients with white-coat HTN [reference (R) group]. Correlations between serum salusin-β level and clinical, laboratory and ambulatory blood pressure (BP) variables were assessed.

RESULTS

The median salusin-β concentration was significantly higher in patients with essential HTN than in those with white-coat HTN (R group). Salusin-β was positively correlated with the body mass index Z-score, systolic and diastolic blood pressure (BP) from three independent measurements, mean systolic BP during the daytime, triglyceride (TG) level, and atherogenic index (TG/high-density lipoprotein-cholesterol ratio).

CONCLUSIONS

The results of this preliminary study suggest that salusin-β may play an important role in the pathogenesis of HTN in a young population. Further research should focus on the role of salusin-β in the mechanism of essential HTN and the assessment of possible correlations between salusin-β and other well-known markers of atherosclerosis in both teenagers and adults. This research should serve as a base for future studies in this field.

Superoxide anions in the paraventricular nucleus mediate cardiac sympathetic afferent reflex in insulin resistance rats

AIM

Cardiac sympathetic afferent reflex (CSAR) participates in sympathetic over-excitation. Superoxide anions and angiotensin II (Ang II) mechanisms are associated with sympathetic outflow and CSAR in the paraventricular nucleus (PVN). This study was designed to investigate whether PVN superoxide anions mediate CSAR and Ang II-induced CSAR enhancement response in fructose-induced insulin resistance (IR) rats.

METHODS

CSAR was evaluated with the changes of renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses to the epicardial application of capsaicin (CAP) in anaesthetized rats.

RESULTS

Compared with Control rats, IR rats showed that CSAR, PVN NAD(P)H oxidase activity, superoxide anions, malondialdehyde (MDA), Ang II and AT1 receptor levels were significantly increased, whereas PVN superoxide dismutase (SOD) and catalase (CAT) activities were decreased. In Control and IR rats, PVN microinjection of superoxide anions scavengers tempol, tiron and PEG-SOD (an analogue of endogenous superoxide dismutase) or inhibition of PVN NAD(P)H oxidase with apocynin caused significant reduction of CSAR, respectively, but DETC (a superoxide dismutase inhibitor) strengthened the CSAR. PVN pre-treatment with tempol abolished, whereas DETC potentiated, Ang II-induced CSAR enhancement response. Moreover, PVN pre-treatment with tempol or losartan prevented superoxide anions increase caused by Ang II in IR rats.

CONCLUSION

PVN superoxide anions mediate CSAR and Ang II-induced CSAR response in IR rats. In IR state, increased NAD(P)H oxidase activity and decreased SOD and CAT activities in the PVN promote superoxide anions increase to involve in CSAR enhancement. Ang II may increase NAD(P)H oxidase activity via AT1 receptor to induce superoxide anion production.

Apelin-13 and APJ in paraventricular nucleus contribute to hypertension via sympathetic activation and vasopressin release in spontaneously hypertensive rats

AIMS

Apelin is a specific endogenous ligand of orphan G protein-coupled receptor APJ. This study was designed to determine the roles and mechanisms of apelin-13 and APJ in paraventricular nucleus (PVN) in renal sympathetic nerve activity (RSNA), arginine vasopressin (AVP) release and mean arterial pressure (MAP) in spontaneously hypertensive rats (SHR).

METHOD

Acute experiment was carried out in 13-week-old male SHR and Wistar-Kyoto rats (WKY) under anaesthesia. RSNA and MAP responses to the PVN microinjection were determined. Apelin and APJ expressions were examined with quantitative real-time PCR and Western blot. AVP and noradrenaline were determined with ELISA. Osmotic minipumps were used for chronic PVN infusion in conscious WKY.

RESULTS

Apelin and APJ in the PVN were up-regulated in SHR. The PVN microinjection of apelin-13 increased, but APJ antagonist F13A decreased the RSNA, MAP, plasma noradrenaline and AVP levels in SHR. N-methyl-D-aspartate receptor (NMDAR) antagonist plus non-NMDAR antagonist abolished the apelin-13-induced sympathetic activation rather than AVP release. NMDAR antagonist or non-NMDAR antagonist alone attenuated the apelin-13-induced sympathetic activation. Chronic infusion of apelin-13 into the PVN in normotensive rats induced hypertension, increased plasma noradrenaline and AVP levels and promoted myocardial atrial natriuretic peptide and beta-myosin heavy chain mRNA expressions, two indicative markers of cardiac hypertrophy.

CONCLUSION

Apelin-13 and APJ in the PVN contribute to hypertension via sympathetic activation and AVP release in SHR. The sympatho-excitatory effect of apeline-13 is mediated by both NMDAR and non-NMDAR in the PVN. Persistent activation of APJ in the PVN induces hypertension.

Brain, liver, and serum salusin-alpha and -beta alterations in Sprague-Dawley rats with or without metabolic syndrome

BACKGROUND

This metabolic syndrome (MetS) study was designed to investigate changes in expression of the neuropeptides salusin-α (Sal-α) and salusin-β (Sal-β) in brain and liver tissue in response to obesity and related changes induced by high-fructose diet and explored how these changes were reflected in the circulating levels of Sal-α and Sal-b, as well as revealing how the lipid profile and concentrations of glucose and uric acid were altered.

MATERIAL/METHODS

The study included 14 Sprague-Dawley rats. The control group was fed ad libitum on standard rat pellets, while the intervention group was given water with 10% fructose in addition to the standard rat pellet for 3 months. Sal-α and Sal-β concentrations in the serum and tissue supernatants were measured by ELISA, and immunohistochemical staining was used to demonstrate expression of the hormones in brain and liver.

RESULTS

Sal-α and Sal-β levels in both the serum and the brain and liver tissue supernatants were lower in the MetS group than the control group. Sal-α and Sal-β were shown by immunohistochemistry to be produced in the brain epithelium, the supraoptic nucleus of the hypothalamus, and the liver hepatocytes.

CONCLUSIONS

The decrease in Sal-α and Sal-β might be involved in the etiopathology of the metabolic syndrome induced by fructose.

Superoxide anions involved in sympathoexcitation and pressor effects of salusin-β in paraventricular nucleus in hypertensive rats

AIMS

Salusin-β in paraventricular nucleus (PVN) increases renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR) and arginine vasopressin (AVP) release in hypertensive rats but not in normal rats. The present study was designed to investigate the downstream molecular mechanism of salusin-β in the PVN in hypertension.

METHOD

Renovascular hypertension was induced by two-kidney, one-clip (2K1C) in male SD rats. Acute experiments were carried out 4 weeks after 2K1C or sham operation under anaesthesia.

RESULTS

MrgA1 mRNA expression and salusin-β level in the PVN as well as plasma salusin-β level were increased in 2K1C rats. Bilateral PVN microinjection of salusin-β increased the RSNA, MAP and HR in 2K1C rats, which were abolished by the pre-treatment with polyethylene glycol-superoxide dismutase (PEG-SOD), the superoxide anion scavenger tempol, the NAD(P)H oxidase inhibitor apocynin or the protein kinase C (PKC) inhibitor chelerythrine chloride (CLC), but not affected by the AT1 receptor antagonist losartan, the Mas receptor antagonist A-779, the NOS inhibitor L-NAME or the GABAA and GABAB receptor antagonists gabazine+CGP-35348. Salusin-β-induced increases in superoxide anion level and NAD(P)H oxidase activity in the PVN were abolished by the PVN pre-treatment with CLC. Salusin-β increased AVP levels in rostral ventrolateral medulla and plasma, which were prevented by the pre-treatment with PEG-SOD, apocynin or CLC in 2K1C rats. Salusin-β augmented the enhanced activity of PKC in the PVN in 2K1C rats.

CONCLUSION

Protein kinase C-NAD(P)H oxidase-superoxide anions pathway in the PVN is involved in salusin-β-induced sympathetic activation, pressor response and AVP release in renovascular hypertension.

Salusins: potential use as a biomarker for atherosclerotic cardiovascular diseases

Human salusin- α and salusin- β are related peptides produced from prosalusin. Bolus injection of salusin- β into rats induces more profound hypotension and bradycardia than salusin- α . Central administration of salusin- β increases blood pressure via release of norepinephrine and arginine-vasopressin. Circulating levels of salusin- α and salusin- β are lower in patients with essential hypertension. Salusin- β exerts more potent mitogenic effects on human vascular smooth muscle cells (VSMCs) and fibroblasts than salusin- α . Salusin- β accelerates inflammatory responses in human endothelial cells and monocyte-endothelial adhesion. Human macrophage foam cell formation is stimulated by salusin- β but suppressed by salusin- α . Chronic salusin- β infusion into apolipoprotein E-deficient mice enhances atherosclerotic lesions; salusin- α infusion reduces lesions. Salusin- β is expressed in proliferative neointimal lesions of porcine coronary arteries after stenting. Salusin- α and salusin- β immunoreactivity have been detected in human coronary atherosclerotic plaques, with dominance of salusin- β in macrophage foam cells, VSMCs, and fibroblasts. Circulating salusin- β levels increase and salusin- α levels decrease in patients with coronary artery disease. These findings suggest that salusin- β and salusin- α may contribute to proatherogenesis and antiatherogenesis, respectively. Increased salusin- β and/or decreased salusin- α levels in circulating blood and vascular tissue are closely linked with atherosclerosis. Salusin- α and salusin- β could be candidate biomarkers and therapeutic targets for atherosclerotic cardiovascular diseases.