Targeted ablation of cardiac sympathetic neurons improves ventricular electrical remodelling in a canine model of chronic myocardial infarction

NBQX mediates ventricular fibrillation susceptibility in rat models of anxiety via the Nrf2/HO-1 pathway

Objective

Anxiety disorder (AD) is a common mental disorder related to cardiovascular disease morbidity. Oxidative stress plays a crucial role in the anxiety state and can lead to cardiac remodeling. Over-activation of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) in cardiomyocytes and neurons can cause oxidative stress. Additionally, the AMPAR inhibitor-2,3-dihydroxy-6-nitro-7-sulfamoyl-benzoquinoxaline-2,3-dione (NBQX) plays an important role in ameliorating oxidative stress. This study aimed to explore the anti-arrhythmic effects of NBQX in a rat model of anxiety.

Methods

The AD model was induced using empty bottle stimulation. Male Sprague Dawley rats were randomly divided into four groups: control + saline, control + NBQX, AD + saline, and AD + NBQX. Open field test was conducted to measure anxiety-like behavior. Electrophysiological experiments, histological analysis, biochemical detection and molecular biology were performed to verify the effects of NBQX on the amelioration of electrical remodeling and structural remodeling. Furthermore, the nuclear factor erythroid 2-related factor 2 (Nrf2) inhibitor (ML385) was used in vitro to demonstrate the signaling pathway.

Results

Oxidative stress levels increased with AMPAR over-activation in AD rats, leading to heightened vulnerability to ventricular fibrillation (VF). NBQX reverses anxiety and VF susceptibility. Our results showed that NBQX activated the Nrf2/heme oxygenase-1 (HO-1) pathway, leading to a decline in oxidative stress levels. Connexin 43 and ion channel expression was upregulated. NBQX treatment attenuated fibrosis and apoptosis. This effect was diminished by ML385 treatment in vitro.

Conclusion

NBQX can alleviate VF susceptibility in rat models of anxiety by alleviating electrical remodeling, structural remodeling via regulating the Nrf2/HO-1 pathway to some extent.

Long-Term Stimulation of the Left Dorsal Branch of the Thoracic Nerve Improves Ventricular Electrical Remodeling in a Canine Model of Chronic Myocardial Infarction

PURPOSE

To evaluate the ventricular electrophysiologic effects of long-term stimulation of the left dorsal branch of thoracic nerve (LDTN) derived from the left stellate ganglion (LSG) in a canine model of chronic myocardial infarction (MI).

METHODS

Seventeen adult male beagles were randomly divided into three groups: the sham group (sham operated, n = 6), the MI group (n = 6), and the MI + LDTN group (MI plus LDTN stimulation, n = 5). The canine model of chronic MI was induced by the occlusion of the left anterior descending artery (LADO). The LDTN was separated and intermittently stimulated immediately after LADO for 2 months. The heart rate variability (HRV) analysis, in vivo electrophysiology, the evaluation of LSG function and neural activity, histological staining, and western blotting (WB) assay were performed to evaluate the effect of LDTN stimulation on the heart.

RESULTS

The canine MI model was successfully established by LADO, and the LDTN was separated and stimulated immediately after LADO. The HRV analysis showed that LDTN stimulation reversed the increased LF value and LF/HF ratio of the MI group. LDTN stimulation prolonged the shortening ERP and APD90, decreased the dispersion of ERP and APD90, and increased the VFT. Additionally, LDTN stimulation inhibits the LSG function and neural activity. Furthermore, LDTN stimulation suppressed the activation of Wnt/β-catenin signaling, which contributed to the LSG neuronal apoptosis by upregulation of pro-apoptotic Bax and downregulation of anti-apoptotic Bcl-2.

CONCLUSION

LDTN stimulation could attenuate cardiac sympathetic remodeling and improve ventricular electrical remodeling, which may be mediated by suppressing the activated Wnt/β-catenin signaling pathway and then promoting the LSG neuronal apoptosis.

Histological and functional assessment of a Takotsubo cardiomyopathy model established by immobilization stress

INTRODUCTION

Takotsubo cardiomyopathy (TTC), also known as stress-induced cardiomyopathy, resembles acute heart failure syndrome but lacks disease-specific diagnosis and treatment strategies. TTC accounts for approximately 5-6% of all suspected cases of acute coronary syndrome in women. At present, animal models of TTC are often created by large amounts of exogenous catecholamines such as isoproterenol. However, isoproterenol injection cannot fully simulate the onset of stress-induced cardiomyopathy in humans since stress is not an instantaneous event.

METHODS

Rats were immobilized for 6 h per day for 1-14 days. To examine whether the TTC model was successful, echocardiography was employed; Elisa detected serum sympathetic activation markers; and the Open-Field test (OFT) was used to analyze behavioral changes in rats after stress. Western blot and histology were used to assess sympathetic remodeling, inflammation levels, and fibrosis; qRT-PCR was used to explore the levels of fibrosis and myocardial hypertrophy. The electrical stability of ventricular was determined by electrophysiological testing.

RESULTS

The rats showed severe stress behavior and local sympathetic remodeling of the heart after only 1 day of stress. After 3 days of stress, the induction of ventricular tachyarrhythmia increased prominently. The highest incidence of TTC in rats was at 5 days of immobilization stress. The pathological left ventricular remodeling caused by immobilization (IMO) stress includes inflammatory infiltration, fibrosis, and myocardial hypertrophy.

CONCLUSIONS

Our study confirms the hypothesis that IMO stress can mimic Takotsubo cardiomyopathy, and the various effects on the heart depending on the duration of IMO stress. We observed the highest incidence of TTC occurred after 5 days of stress. Furthermore, there is a gradual occurrence of electrical and structural remodeling as the stress duration prolongs.

Chronic Expression of Interleukin-10 Transgene Modulates Cardiac Sympathetic Ganglion Resulting in Reduced Ventricular Arrhythmia

The cardiac autonomic nervous system (CANS) is intimately connected to the regulation of electrophysiology and arrhythmogenesis in cardiac systems. This work aimed at investigating whether interleukin-10 (IL-10) could effectively modulate CANS and suppress ischemia-induced ventricular arrhythmia (VA) through chronically acting on the cardiac sympathetic ganglion (CSG). Using an adeno-associated virus (AAV), we achieved local chronic overproduction of IL-10 in the CSG, left stellate ganglion (LSG). As a result, in the IL-10 group, we observed a decreased number of tyrosine hydroxylase-positive (TH+) cells in the LSG. IL-10 markedly downregulated the nerve growth factor, synaptophysin, as well as growth-associated protein 43 expression. In vivo, results from ambulatory electrocardiography showed that IL-10 overexpression significantly inhibited the cardiac sympathetic nervous system activity and improved heart rate variability. Meanwhile, we observed decreased LSG function as well as prolonged ventricular effective refractory period and suppressed VA after myocardial infarction (MI) in the IL-10 group. In addition, IL-10 overexpression attenuated inflammation and decreased norepinephrine levels in the myocardium after acute MI. In conclusion, our data suggest that chronic IL-10 overexpression modulates cardiac sympathetic nerve remodeling and suppresses VA induced by MI. Neuromodulation through AAV-mediated IL-10 overexpression may have the characteristics of and advantages as a potential neuroimmunotherapy for preventing MI-induced VAs.

Low-intensity pulsed ultrasound treatment mitigates ventricular arrhythmias via inhibiting microglia-mediated neuroinflammation in heart failure rat model

BACKGROUND

Sympathetic overactivation plays an important role in heart failure (HF)-induced ventricular arrhythmias (VAs). Microglia-mediated neuroinflammation could contribute to sympathetic overactivation. A previous study demonstrated that low-intensity pulsed ultrasound (LIPUS) could inhibit neuroinflammation. However, whether LIPUS could attenuate HF-induced VAs via inhibiting microglia-mediated neuroinflammation remains largely unknown.

METHODS

Forth Sprague-Dawley male rats were averagely randomized into four groups: CTL (control) group, CTL + LIPUS group, HF group and HF + LIPUS. Surgical ligation of the coronary artery was used for induction of HF. In vivo electrophysiological study was performed to check VAs susceptibility. Left stellate ganglion (LSG) neural activity and heart rate variability (HRV) were used to test sympathetic nerve activity.

RESULTS

Compared to the HF group, LIPUS treatment significantly ameliorated HF-induced cardiac hypertrophy, fibrosis, and dysfunction. In addition, LIPUS treatment markedly inhibited HF-induced VAs susceptibility and reversed gap junction remodeling. LIPUS treatment obviously inhibited microglial activation and neuroinflammation in PVN, sympathetic hyperactivity in the LSG and proinflammatory cytokines releases in the ventricle. P2X7/NLRP3 signaling pathway may be involved in the anti-arrhythmic effect of LIPUS treatment following HF.

CONCLUSIONS

Our data demonstrated that LIPUS treatment protected against HF-induced VAs via alleviating microglia-mediated neuroinflammation, sympathetic overactivation and proinflammatory cytokines releases through inhibiting P2X7/NLRP3 signaling. This study provides novel insight into the therapeutic potential of LIPUS.

25 years of basic and translational science in EP Europace: novel insights into arrhythmia mechanisms and therapeutic strategies

In the last 25 years, EP Europace has published more than 300 basic and translational science articles covering different arrhythmia types (ranging from atrial fibrillation to ventricular tachyarrhythmias), different diseases predisposing to arrhythmia formation (such as genetic arrhythmia disorders and heart failure), and different interventional and pharmacological anti-arrhythmic treatment strategies (ranging from pacing and defibrillation to different ablation approaches and novel drug-therapies). These studies have been conducted in cellular models, small and large animal models, and in the last couple of years increasingly in silico using computational approaches. In sum, these articles have contributed substantially to our pathophysiological understanding of arrhythmia mechanisms and treatment options; many of which have made their way into clinical applications. This review discusses a representative selection of EP Europace manuscripts covering the topics of pacing and ablation, atrial fibrillation, heart failure and pro-arrhythmic ventricular remodelling, ion channel (dys)function and pharmacology, inherited arrhythmia syndromes, and arrhythmogenic cardiomyopathies, highlighting some of the advances of the past 25 years. Given the increasingly recognized complexity and multidisciplinary nature of arrhythmogenesis and continued technological developments, basic and translational electrophysiological research is key advancing the field. EP Europace aims to further increase its contribution to the discovery of arrhythmia mechanisms and the implementation of mechanism-based precision therapy approaches in arrhythmia management.

Mechanistic insights into spontaneous transition from cellular alternans to ventricular fibrillation

T-wave alternans (TWA) has been used for predicting the risk of malignant cardiac arrhythmias and sudden cardiac death (SCD) in multiple clinical settings; however, possible mechanism(s) underlying the spontaneous transition from cellular alternans reflected by TWA to arrhythmias in impaired repolarization remains unclear. The healthy guinea pig ventricular myocytes under E-4031 blocking IKr (0.1 μM, N = 12; 0.3 μM, N = 10; 1 μM, N = 10) were evaluated using whole-cell patch-clamp. The electrophysiological properties of isolated perfused guinea pig hearts under E-4031 (0.1 μM, N = 5; 0.3 μM, N = 5; 1 μM, N = 5) were evaluated using dual- optical mapping. The amplitude/threshold/restitution curves of action potential duration (APD) alternans and potential mechanism(s) underlying the spontaneous transition of cellular alternans to ventricular fibrillation (VF) were examined. There were longer APD80 and increased amplitude and threshold of APD alternans in E-4031 group compared with baseline group, which was reflected by more pronounced arrhythmogenesis at the tissue level, and were associated with steep restitution curves of the APD and the conduction velocity (CV). Conduction of AP alternans augmented tissue's functional spatiotemporal heterogeneity of regional AP/Ca alternans, as well as the AP/Ca dispersion, leading to localized uni-directional conduction block that spontaneous facilitated the formation of reentrant excitation waves without the need for additional premature stimulus. Our results provide a possible mechanism for the spontaneous transition from cardiac electrical alternans in cellular action potentials and intercellular conduction without the involvement of premature excitations, and explain the increased susceptibility to ventricular arrhythmias in impaired repolarization. In this study, we implemented voltage-clamp and dual-optical mapping approaches to investigate the underlying mechanism(s) for the arrhythmogenesis of cardiac alternans in the guinea pig heart at cellular and tissue levels. Our results demonstrated a spontaneous development of reentry from cellular alternans, arising from a combined actions of restitution properties of action potential duration, conduction velocity of excitation wave and interplay between alternants of action potential and the intracellular Ca handling. We believe this study provides new insights into underlying the mechanism, by which cellular cardiac alternans spontaneously evolves into cardiac arrhythmias.

Monotropein attenuates doxorubicin-induced oxidative stress, inflammation, and arrhythmia via the AKT signal pathway

As a glycoside iridoid, monotropein (MON) has a wide range of pharmacological properties, including anti-inflammatory, antioxidant, and anti-apoptotic effects. However, few studies have investigated MON's cardiovascular protective effects. Therefore, this study aimed to explore the role of MON in doxorubicin (DOX)-induced cardiotoxicity. To establish the myocardial toxicity model, mice were intraperitoneally injected with DOX. After admimistration of DOX, myocardial injury markers were increased, cardiac function was reduced, and pathological changes were observed in the myocardium, indicating successful construction of the myocardial injury model. Our study showed that MON treatment mitigated DOX-induced myocardial damage and improved cardiac dysfunction. In addition, DOX-treated mice displayed higher levels of inflammation and oxidative stress, while MON treatment also reversed these pathological changes. Moreover, DOX-treated mice were more susceptible to ventricular fibrillation, whereas MON reduced ventricular fibrillation incidence. Further studies have shown that MON could reverse DOX-induced inhibition of the AKT signaling pathway. Besides, the application of AKT inhibitor could partially abolish MON's cardioprotective effects. To conclude, this study demonstrated the ability of MON to reduce DOX-induced myocardial damage, cardiac dysfunction, inflammation, and oxidative stress, as well as ventricular fibrillation risk. These may attributable to the activation of the AKT pathway.

Effects and mechanism of renal denervation on ventricular arrhythmia after acute myocardial infarction in rats

BACKGROUND

Renal denervation (RDN) can reduce ventricular arrhythmia after acute myocardial infarction (AMI), but the mechanism is not clear. The purpose of this study is to study its mechanism.

METHODS

Thirty-two Sprague-Dawley rats were divided into four groups: control group, AMI group, RDN-1d + AMI group, RDN-2w + AMI group. The AMI model was established 1 day after RDN in the RDN-1d + AMI group and 2 weeks after RDN in the RDN-2w + AMI group. At the same time, 8 normal rats were subjected to AMI modelling (the AMI group). The control group consisted of 8 rats without RDN intervention or AMI modelling.

RESULTS

The study confirmed that RDN can reduce the occurrence of ventricular tachycardia in AMI rats, reduce renal sympathetic nerve discharge, and inhibit the activity of local sympathetic nerves and cell growth factor (NGF) protein expression in the heart after AMI. In addition, RDN decreased the expression of norepinephrine (NE) and glutamate in the hypothalamus,and NE in cerebrospinal fluid, and increased the expression level of γ aminobutyric acid (GABA) in the hypothalamus after AMI.

CONCLUSION

RDN can effectively reduce the occurrence of ventricular arrhythmia after AMI, and its main mechanism may be via the inhibition of central sympathetic nerve discharge.

Colchicine prevents ventricular arrhythmias vulnerability in diet-induced obesity rats

AIMS

This study aimed to assess the role of colchicine in ventricular arrhythmias (VAs) induced by high fat diet (HFD)-fed rats.

METHODS AND RESULTS

Male rats were divided into four groups: CTL, normal diet plus saline; CTC, normal diet plus colchicine; HFD, HFD plus saline; HFC: HFD plus colchicine. Metabolic parameters, ECG parameters, ventricular electrophysiological parameters, ventricular histology, Western blot and RT-qPCR were measured. Compared with the HFD group, colchicine treatment significantly improved metabolic parameters, reduced ventricular fibrosis, increased the expression of Cav1.2, Kv4.2, Nav1.5, and Cx43, reduced CaMKII, p-CaMKII, p-RyR2 (S2808), and p-RyR2 (S2814) expression in LV. Furthermore, colchicine inhibited the inflammatory responses, prolonged ventricular effective refractory period (ERP), reduced corrected QT interval (QTc) and Tpeak-Tend interval, so as to reduce the susceptibility to VAs in obesity rats.

CONCLUSIONS

Colchicine could mitigate ventricular fibrosis, ventricular electrical remodeling, as well as the expression of ion channels, and inhibit obesity-induced inflammatory responses, which provides a new idea for colchicine to prevent VAs in obese individuals.

17β-Oestradiol facilitates M2 macrophage skewing and ameliorates arrhythmias in ovariectomized female infarcted rats

Epidemiological studies have suggested a lower incidence of arrhythmia‐induced sudden cardiac death in women than in men. 17β‐oestradiol (E2) has been reported to have a post‐myocardial infarction antiarrhythmic effect, although the mechanisms have yet to be elucidated. We investigated whether E2‐mediated antioxidation regulates macrophage polarization and affects cardiac sympathetic reinnervation in rats after MI. Ovariectomized Wistar rats were randomly assigned to placebo pellets, E2 treatment, or E2 treatment +3‐morpholinosydnonimine (a peroxynitrite generator) and followed for 4 weeks. The infarct sizes were similar among the infarcted groups. At Day 3 after infarction, post‐infarction was associated with increased superoxide levels, which were inhibited by administering E2. E2 significantly increased myocardial IL‐10 levels and the percentage of regulatory M2 macrophages compared with the ovariectomized infarcted alone group as assessed by immunohistochemical staining, Western blot and RT‐PCR. Nerve growth factor colocalized with both M1 and M2 macrophages at the magnitude significantly higher in M1 compared with M2. At Day 28 after infarction, E2 was associated with attenuated myocardial norepinephrine levels and sympathetic hyperinnervation. These effects of E2 were functionally translated in inhibiting fatal arrhythmias. The beneficial effect of E2 on macrophage polarization and sympathetic hyperinnervation was abolished by 3‐morpholinosydnonimine. Our results indicated that E2 polarized macrophages into the M2 phenotype by inhibiting the superoxide pathway, leading to attenuated nerve growth factor‐induced sympathetic hyperinnervation after myocardial infarction.

Proteomic Sequencing of Stellate Ganglions in Rabbits With Myocardial Infarction

The stellate ganglion (SG) of the autonomic nervous system plays important role in cardiovascular diseases (CDs). Myocardial infarction (MI) is associated with sustained increasing cardiac sympathetic nerve activity. Expressions and functions of proteins in SG tissue after MI are remaining unclear. This study is to explore the expression characteristics of proteins in SGs associated with MI. Japanese big-ear white rabbits (n = 22) were randomly assigned to the control group and MI group. The MI model was established by left anterior descending coronary artery ligation and confirmed by serum myocardial enzymes increasing 2,3,5-triphenyltetrazolium (TTC) staining and echocardiography. The expressions of proteins in rabbit SGs after MI were detected using tandem mass tags (TMT) quantitative proteomic sequencing. There were 3,043 credible proteins were predicted in rabbit SG tissues and 383 differentially expressed proteins (DEPs) including 143 upregulated and 240 downregulated proteins. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the DEPs involved in adrenergic signaling in cardiomyocytes, positive regulation of ERK1 and ERK2 cascade, and other biological processes. Three kinds of proteins directly correlated to CDs were selected to be validated by the subsequent western blot experiment. This study first identified the characterization of proteins in rabbit SG after MI, which laid a solid foundation for revealing the mechanism of roles of SG on the MI process.

Pinocembrin ameliorates arrhythmias in rats with chronic ischaemic heart failure

OBJECTIVE

Ventricular arrhythmias (VAs) are a common complication of chronic ischaemic heart failure (CIHF). The purpose of this study is to investigate the efficacy of pinocembrin in a rat model of VAs induced by CIHF and further examine the possible mechanism.

METHODS

Rats were subjected to ligation of left anterior descending coronary artery to mimic CIHF and then received pinocembrin treatment daily for 2 months. The vivo electrophysiology were performed to determine the effect of pinocembrin on ventricular electrical activity. The expression of Cav1.2, Kv4.2, and NGF was determined by Western blot. The structural change of ventricle was tested by the Echocardiography, Masson staining, and HE staining. The effect of pinocembrin on sympathetic nerve-related markers was detected by the immunostaining and the ELISA was used to test for biomarkers associated with heart failure.

RESULTS

Pinocembrin increased the expression of ion channel protein Cav1.2 and Kv4.3, ameliorated the shortening of action potential duration (APD) and reduced the incidence and duration of ventricular fibrillation (VF). Pinocembrin also reduced the expression of nerve growth factor (NGF) and improved the autonomic nerve remodelling. In addition, pinocembrin reduced the area of infarct area and myocardial fibrosis, accompanied by increasing the expression of connexin protein 43 (C_X43).

CONCLUSION

We demonstrate that pinocembrin reduces cardiac nerve remodelling and protects against Vas induced by CIHF. The findings suggest that pinocembrin can be a promising candidate for the treatment of VAs.

Sympatho-adrenergic mechanisms in heart failure: new insights into pathophysiology

The sympathetic nervous system is activated in the setting of heart failure (HF) to compensate for hemodynamic instability. However, acute sympathetic surge or sustained high neuronal firing rates activates β-adrenergic receptor (βAR) signaling contributing to myocardial remodeling, dysfunction and electrical instability. Thus, sympatho-βAR activation is regarded as a hallmark of HF and forms pathophysiological basis for β-blocking therapy. Building upon earlier research findings, studies conducted in the recent decades have significantly advanced our understanding on the sympatho-adrenergic mechanism in HF, which forms the focus of this article. This review notes recent research progress regarding the roles of cardiac β2AR or α1AR in the failing heart, significance of β1AR-autoantibodies, and βAR signaling through G-protein independent signaling pathways. Sympatho-βAR regulation of immune cells or fibroblasts is specifically discussed. On the neuronal aspects, knowledge is assembled on the remodeling of sympathetic nerves of the failing heart, regulation by presynaptic α2AR of NE release, and findings on device-based neuromodulation of the sympathetic nervous system. The review ends with highlighting areas where significant knowledge gaps exist but hold promise for new breakthroughs.

Electrophysiological Mechanisms Underlying T-Wave Alternans and Their Role in Arrhythmogenesis

T-wave alternans (TWA) reflects every-other-beat alterations in the morphology of the electrocardiogram ST segment or T wave in the setting of a constant heart rate, hence, in the absence of heart rate variability. It is believed to be associated with the dispersion of repolarization and has been used as a non-invasive marker for predicting the risk of malignant cardiac arrhythmias and sudden cardiac death as numerous studies have shown. This review aims to provide up-to-date review on both experimental and simulation studies in elucidating possible mechanisms underlying the genesis of TWA at the cellular level, as well as the genesis of spatially concordant/discordant alternans at the tissue level, and their transition to cardiac arrhythmia. Recent progress and future perspectives in antiarrhythmic therapies associated with TWA are also discussed.

Effects of ticagrelor pretreatment on electrophysiological properties of stellate ganglion neurons following myocardial infarction

Higher sympathetic activity predisposes to malignant ventricular arrhythmias in the context of myocardial infarction (MI). This is, in part, mediated by the electrical activity of the stellate ganglion (SG). The aim of this study is to examine the effects of ticagrelor pretreatment on the electrophysiological properties of SG neurons following MI in rabbits. MI was induced by isoproterenol (ISO) of 150 mg kg-1 d-1 (twice at an interval of 24 hours). Ticagrelor pretreatment was administered at low- (10 mg kg-1 d-1) or high-dose (20 mg kg-1 d-1). Protein and RNA expression were determined by immunohistochemical analysis and real-time PCR, respectively. The activity of sodium channel current (INa), delayed rectifier potassium current (IKDR), M-type potassium current (IKM) as well as action potentials (APs) from SG neurons were measured by whole-cell patch-clamp. Intracellular calcium concentrations were measured by confocal microscopy. Compared with the control group, the MI group exhibited a greater amplitude of INa, IKDR and IKM, significantly altered activation and inactivation characteristics of INa, no significant alterations in protein or mRNA expression of sodium and M-type potassium channels, along with higher AP amplitude and frequency and intracellular calcium concentrations. Most of these abnormalities were prevented by pretreatment with low- or high-dose ticagrelor. Our data suggest that ticagrelor exerts cardioprotective effects, potentially through modulating the activity of different ion channels in SG neurons.

Pinocembrin Decreases Ventricular Fibrillation Susceptibility in a Rat Model of Depression

Background: Depression is associated with the increased risk of mortality and morbidity and is an independent risk factor for many cardiovascular diseases. Depression may promote cardiac arrhythmias, but little is known about the mechanisms. Pinocembrin mitigated depressive-like behaviors and exhibited cardioprotective effects in several models; however, whether pinocembrin benefits ventricular arrhythmias in depression models has not been elucidated. Thus, this study was to evaluate the effects of pinocembrin on ventricular fibrillation susceptibility in rat models of depression.

Methods: Male Sprague-Dawley rats were randomly assigned into control, control + pinocembrin, MDD (major depressive disorder), and MDP (MDD + pinocembrin) groups, respectively. Depressive-like behaviors, ventricular electrophysiological parameters, electrocardiogram parameters, heart rate variability, ventricular histology, serum norepinephrine, tumor necrosis factor-α, and interleukin-1β were detected. Protein levels in left ventricle were measured by Western blot assays.

Results: Compared with the MDD group, pinocembrin significantly mitigated depressive-like behaviors, prolonged ventricular effective refractory period, action potential duration, QT, and corrected QT (QTc) interval, improved heart rate variability, decreased Tpeak–Tend interval, ventricular fibrillation inducibility rate, ventricular fibrosis, ventricular positive nerve densities, and protein expression of tyrosine hydroxylase and growth associated protein-43, reduced serum norepinephrine, tumor necrosis factor-α, interleukin-1β concentrations, and the expression levels of p-IκBα and p-p65, and increased the protein expression of Cx43, Cav1.2, and Kv.4.2 in the MDP group.

Conclusion: Pinocembrin attenuates ventricular electrical remodeling, autonomic remodeling, and ion-channel remodeling, lowers ventricular fibrosis, and suppresses depression-induced inflammatory responses, providing new insights in pinocembrin and ventricular arrhythmias in depressed patients.

Pinocembrin attenuates autonomic dysfunction and atrial fibrillation susceptibility via inhibition of the NF-κB/TNF-α pathway in a rat model of myocardial infarction

Previous studies indicate that myocardial infarction (MI) may contribute to atrial fibrillation (AF). Emerging evidence has shown that pinocembrin protects myocardial ischemic injury (I/R)-induced cardiac fibrosis and arrhythmias in animals via its anti-inflammatory or antioxidant activities. However, the effects of pinocembrin on MI-induced atrial arrhythmias remain unknown. Thus, this study aimed to investigate the effects of pinocembrin on autonomic dysfunction and AF susceptibility in MI rats and the possible mechanism. In a standard experimental MI model, Sprague-Dawley rats received permanent ligation of the left anterior descending (LAD) coronary artery and were treated with pinocembrin or saline for 6 days. Our results demonstrated that pinocembrin treatment significantly decreased sympathetic activity, augmented parasympathetic activity, improved heart rate variability (HRV), prolonged the atrial effective refractory period (ERP) and action potential duration (APD), shortened activation latency (AL), lowered the indicibility rate of AF, attenuated atrial fibrosis, and decreased concentrations of norepinephrine (NE), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 in the serum and the left atrial (LA). Furthermore, pinocembrin treatment significantly increased the expression levels of Cx43 and Cav1.2 and suppressed the phosphorylation of inhibitor-κBα (IκBα) and the activation of nuclear factor-kappa B (NF-κB)subunit p65. In conclusion, the findings indicate that pinocembrin treatment decreases autonomic remodeling, lowers atrial fibrosis, ameliorates atrial electrical remodeling, and suppresses MI-induced inflammatory responses, which suggests a potential novel strategy for atrial arrhythmias.

Analysis of Effect of Schisandra in the Treatment of Myocardial Infarction Based on Three-Mode Gene Ontology Network

Schisandra chinensis is a commonly used traditional Chinese medicine, which has been widely used in the treatment of acute myocardial infarction in China. However, it has been difficult to systematically clarify the major pharmacological effect of Schisandra, due to its multi-component complex mechanism. In order to solve this problem, a comprehensive network analysis method was established based-on “component–gene ontology–effect” interactions. Through the network analysis, reduction of cardiac preload and myocardial contractility was shown to be the major effect of Schisandra components, which was further experimentally validated. In addition, the expression of NCOR2 and NFAT in myocyte were experimentally confirmed to be associated with Schisandra in the treatment of AMI, which may be responsible for the preservation effect of myocardial contractility. In conclusion, the three-mode gene ontology network can be an effective network analysis workflow to evaluate the pharmacological effects of a multi-drug complex system.

Cardiac Sympathetic Afferent Denervation Protects Against Ventricular Arrhythmias by Modulating Cardiac Sympathetic Nerve Activity During Acute Myocardial Infarction

Background

Augmented cardiac sympathetic afferent reflex (CSAR) plays a role in enhanced sympathetic activity. Given that a strategy for abolishing augmented CSAR-induced sympathetic activation may be beneficial for protecting against ventricular arrhythmias (VAs) triggered by acute myocardial infarction (AMI), we investigated whether cardiac sympathetic afferent denervation (CSAD) could protect against VAs by modulating cardiac sympathetic nerve activity in an AMI dog model.

Material/Methods

Twenty-two anesthetized dogs were assigned to the CSAD group (n=9) and the sham group (n=13) randomly. CSAD was produced by epicardial application of resiniferatoxin. Heart rate variability (HRV), ventricular action potential duration (APD), APD dispersion, beat-to-beat variability of repolarization (BVR), effective refractory period (ERP) of ventricles, ERP dispersion, plasma norepinephrine (NE) concentration, and left stellate ganglion (LSG) neural activity were determined at baseline and after CSAD. We designed an AMI model by occluding the left anterior coronary artery, and performed analysis of VAs for 60 minutes using electrocardiography. Then, levels of c-fos and nerve growth factor (NGF) were determined.

Results

Relative to baseline values, CSAD prolonged ERP and APD of ventricles, increased HRV, decreased APD dispersion, BVR, ERP dispersion and serum NE concentration, and attenuated LSG activity in the CSAD group. AMI triggered a remarkable increase in LSG activity and function but decreased the HRV of the sham group animals relative to the CSAD group. Moreover, the CSAD group had higher levels of VAs relative to the sham group. This was accompanied by a corresponding decrease in proteins quantities of NGF and c-fos in the CSAD group in the LSG after AMI compared to the sham group.

Conclusions

CSAD can suppress LSG neural activity, hence enhance the electrophysiological stability and protect the heart from AMI-triggered VAs.

Multiplex Detection of Five Canine Viral Pathogens for Dogs as Laboratory Animals by the Luminex xTAG Assay

More and more dogs have been used as a disease model for medical research and drug safety evaluation. Therefore, it is important to make sure that the dogs and their living houses are special pathogen free. In this study, the development and evaluation of a Luminex xTAG assay for simultaneous detection of five canine viruses was carried out, including canine distemper virus, canine parvovirus, canine parainfluenza virus, canine adenovirus, and rabies virus. Assay specificity was accomplished by targeting conserved genomic regions for each virus. Hybridization between multiplexed PCR products and the labeled fluorescence microspheres was detected in a high throughput format using a Luminex fluorescence reader. The Luminex xTAG assay showed high sensitivity with limits of detection for the five viruses was 100 copies/μL. Specificity of the xTAG assay showed no amplification of canine coronavirus, pseudorabies virus and canine influenza virus indicating that the xTAG assay was specific. Seventy-five clinical samples were tested to evaluate the xTAG assay. The results showed 100% coincidence with the conventional PCR method. This is the first report of a specific and sensitive multiplex Luminex xTAG assay for simultaneous detection of five major canine viral pathogens. This assay will be a useful tool for quality control and environmental monitoring for dogs used as laboratory animals, may even be applied in laboratory epidemiological investigations.