Effect and possible mechanisms of saponins in Chinese herbal medicine exerts for the treatment of myocardial ischemia-reperfusion injury in experimental animal: a systematic review and meta-analysis

Introduction

Preventing ischemia-reperfusion injury is the main direction of myocardial infarction treatment in the convalescent stage. Some studies have suggested that saponins in Traditional Chinese medicine (TCM) preparations can protect the myocardium by various mechanisms. Our meta-analysis aims to evaluate the efficacy of TCM saponins in treating myocardial ischemia-reperfusion injury (MIRI) and to summarize the potential molecular mechanisms further.

Methods

We conducted a literature search in six electronic databases [Web of Science, PubMed, Embase, Cochrane Library, Sinomed, China National Knowledge Infrastructure (CNKI)] until October 2022.

Results

Seventeen eligible studies included 386 animals (254 received saponins and 132 received vehicles). The random effect model is used to calculate the combined effect. The effect size is expressed as the weighted average difference (WMD) and 95% confidence interval (CI). Compared with placebo, saponins preconditioning reduced infarct size after MIRI significantly (WMD: -3.60,95% CI: -4.45 to -2.74, P < 0.01, I2: 84.7%, P < 0.001), and significantly increased EF (WMD: 3.119, 95% CI: 2.165 to 4.082, P < 0.01, I2: 82.9%, P < 0.0 L) and FS (WMD: 3.157, 95% CI: 2.218 to 4.097, P < 0.001, I2: 81.3%, P < 0.001).

Discussion

The results show that the pre-administration of saponins from TCM has a significant protective effect on MIRI in preclinical studies, which provides an application prospect for developing anti-MIRI drugs with high efficiency and low toxicity.

Roles and mechanisms of natural drugs on sinus node dysfunction

Sinus node dysfunction is a common arrhythmia disorder with a high incidence and significant social and economic burden. Currently, there are no effective drugs for treating chronic sinus node dysfunction. The disease is associated with ion channel disturbances caused by aging, fibrosis, inflammation, oxidative stress, and autonomic dysfunction. Natural active substances and Chinese herbal medicines have been widely used and extensively studied in the medical community for the treatment of arrhythmias. Multiple studies have demonstrated that various active ingredients and Chinese herbal medicines, such as astragaloside IV, quercetin, and ginsenosides, exhibit antioxidant effects, reduce fibrosis, and maintain ion channel stability, providing promising drugs for treating sinus node dysfunction. This article summarizes the research progress on natural active ingredients and Chinese herbal formulas that regulate sick sinoatrial node function, providing valuable references for the treatment of sinus node dysfunction.

Review on the protective mechanism of astragaloside IV against cardiovascular diseases

Cardiovascular disease is a global health problem. Astragaloside IV (AS-IV) is a saponin compound extracted from the roots of the Chinese herb Astragalus. Over the past few decades, AS-IV has been shown to possess various pharmacological properties. It can protect the myocardium through antioxidative stress, anti-inflammatory effects, regulation of calcium homeostasis, improvement of myocardial energy metabolism, anti-apoptosis, anti-cardiomyocyte hypertrophy, anti-myocardial fibrosis, regulation of myocardial autophagy, and improvement of myocardial microcirculation. AS-IV exerts protective effects on blood vessels. For example, it can protect vascular endothelial cells through antioxidative stress and anti-inflammatory pathways, relax blood vessels, stabilize atherosclerotic plaques, and inhibit the proliferation and migration of vascular smooth muscle cells. Thus, the bioavailability of AS-IV is low. Toxicology indicates that AS-IV is safe, but should be used cautiously in pregnant women. In this paper, we review the mechanisms of AS-IV prevention and treatment of cardiovascular diseases in recent years to provide a reference for future research and drug development.

Astragalosides Supplementation Enhances Intrinsic Muscle Repair Capacity Following Eccentric Exercise-Induced Injury

Astragalosides have been shown to enhance endurance exercise capacity in vivo and promote muscular hypertrophy in vitro. However, it remains unknown whether astragalosides supplementation can alter inflammatory response and enhance muscle recovery after damage in humans. We therefore aimed to evaluate the effect of astragalosides supplementation on muscle's intrinsic capacity to regenerate and repair itself after exercise-induced damage. Using a randomized double-blind placebo-controlled cross-over design, eleven male participants underwent 7 days of astragalosides supplementation (in total containing 4 mg of astragalosides per day) or a placebo control, following an eccentric exercise protocol. Serum blood samples and variables related to muscle function were collected prior to and immediately following the muscle damage protocol and also at 2 h, and 1, 2, 3, 5, and 7 days of the recovery period, to assess the pro-inflammatory cytokine response, the secretion of muscle regenerative factors, and muscular strength. Astragalosides supplementation reduced biomarkers of skeletal muscle damage (serum CK, LDH, and Mb), when compared to the placebo, at 1, 2, and 3 days following the muscle damage protocol. Astragalosides supplementation suppressed the secretion of IL-6 and TNF-α, whilst increasing the release of IGF-1 during the initial stages of muscle recovery. Furthermore, following astragaloside supplementation, muscular strength returned to baseline 2 days earlier than the placebo. Astragalosides supplementation shortens the duration of inflammation, enhances the regeneration process and restores muscle strength following eccentric exercise-induced injury.

Astragalus Mongholicus: A review of its anti-fibrosis properties

Background: Fibrosis-related diseases (FRD) include cerebral fibrosis, pulmonary fibrosis, cardiac fibrosis, liver fibrosis, renal fibrosis, peritoneal fibrosis, etc. The effects of fibrosis can be severe, resulting in organ dysfunction, functional decline, and even organ failure, which can cause serious health problems.

Aim: Currently, there is no effective modern medicine for anti-fibrosis in the clinics; however, Chinese medicine has a certain beneficial effect on treating such diseases. Astragalus Mongholicus (AM) has rich medicinal value, and its anti-fibrosis effect has been recently investigated. In recent years, more and more experimental studies have been conducted on the intervention of astragaloside IV (AS-IV), astragalus polysaccharide (APS), astragalus flavone, cycloastragalus alcohol, astragalus water extract and other pharmacological components in fibrosis-related diseases, attracting the interest of researchers. We aim to provide ideas for future research by summarizing recent research advances of AM in treating fibrosis-related diseases.

Methods: A literature search was conducted from the core collections of electronic databases such as Baidu Literature, Sciencen.com, Google Scholar, PubMed, and Science Direct using the above keywords and the pharmacological and phytochemical details of the plant.

Results: AM can be used to intervene in fibrosis-disease progression by regulating inflammation, oxidative stress, the immune system, and metabolism.

Conclusion: AS-IV, APS, and astragalus flavone were studied and discussed in detail. These components have high potential anti-fibrosis activity. Overall, this review aims to gain insight into the AM’s role in treating fibro-related diseases.

Inhibition of miRNA-1-Mediated Inflammation and Autophagy by Astragaloside IV Improves Lipopolysaccharide-Induced Cardiac Dysfunction in Rats

Introduction

Astragaloside IV (AS-IV) is one of the main active components isolated from the traditional Chinese medicinal herb, Astragalus membranaceus. The present study was designed to investigate whether the regulation of microRNA-1 (miR-1)-mediated inflammation and autophagy contributes to the protective effect of AS-IV against cardiac dysfunction in rats treated with lipopolysaccharides (LPS).

Methods

Animal model of cardiac dysfunction in rats or cellular model of injured H9c2 heart cell line was established by using LPS. Echocardiography, electron microscopy, enzyme-linked immunosorbent assay, immunofluorescence, quantitative RT-PCR, and Western blotting were used to determine the cardiac function and expression of inflammation- and autophagy-related proteins at both the mRNA and protein levels.

Results

LPS caused cardiac dysfunction in rats or injury in H9c2 cells and induced inflammation and autophagy. Compared with LPS treatment, AS-IV treatment attenuated cardiac dysfunction or cell injury, accompanied by inhibition of inflammation and autophagy. However, the miR-1 mimics partly abolished the effects of AS-IV. In addition, the effect of the miR-1 inhibitor was similar to that of AS-IV in the LPS model. Further analyses showed that AS-IV treatment decreased the mRNA expression of miR-1 in the heart tissue of rats and H9c2 cells treated with LPS.

Conclusion

These results suggest that AS-IV attenuated cardiac dysfunction caused by LPS by inhibiting miR-1-mediated inflammation and autophagy, thereby providing a novel mechanism for the protection against cardiac diseases.

Astragaloside IV Alleviates Infarction Induced Cardiomyocyte Injury by Improving Mitochondrial Morphology and Function

The protective effect of astragaloside IV (AS-IV) on myocardial injury after myocardial infarction has been reported. However, the underlying mechanism is still largely unknown. We established a myocardial infarction model in C57BL/6 mice and injected intraperitoneally with 10 mg/kg/d AS-IV for 4 weeks. The cardiac function, myocardial fibrosis, and angiogenesis were investigated by echocardiography, Masson's trichrome staining, and CD31 and smooth muscle actin staining, respectively. Cardiac mitochondrial morphology was visualized by transmission electron microscopy. Cardiac function, infarct size, vascular distribution, and mitochondrial morphology were significantly better in AS-IV-treated mice than in the myocardial infarction model mice. In vitro, a hypoxia-induced H9c2 cell model was established to observe cellular apoptosis and mitochondrial function. H9c2 cells transfected with silent information regulator 3 (Sirt3) targeting siRNA were assayed for Sirt3 expression and activity. Sirt3 silencing eliminated the beneficial effects of AS-IV and abrogated the inhibitory effect of AS-IV on mitochondrial division. These results suggest that AS-IV protects cardiomyocytes from hypoxic injury by maintaining mitochondrial homeostasis in a Sirt3-dependent manner.

A Single, Acute Astragaloside IV Therapy Protects Cardiomyocyte Through Attenuating Superoxide Anion-Mediated Accumulation of Autophagosomes in Myocardial Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion (I/R) injury, characterized by myocardial cell death (e.g., apoptosis) and generation of reactive oxygen species (ROS) such as superoxide (O₂ ^·-) and hydrogen peroxide (H₂O₂), is a serious threat to human health and property. Saponin astragaloside IV (ASIV), extracted from Chinese herbal medicine astragalus, is effective in resolving multiple pathological issues including myocardial I/R injury. Recent studies have shown that autophagy is regulated by ROS and plays an important role in myocardial I/R injury. However, regulation of autophagy by ASIV during myocardial I/R injury and the role of specific ROS involved in the process have been rarely reported. In the present study, we found that SOD2 was downregulated and O₂ ^·- was upregulated in H₂O₂-induced H9C2 cardiac myocyte injury in vitro and myocardial I/R injury in vivo, while such alterations were reversed by ASIV. ASIV possessed the ability to alleviate myocardial I/R injury via attenuating I/R-caused autophagosome accumulation. Upregulate of O₂ ^·- by 2-methoxyestradiol (2-ME) reversed the effect of ASIV-mediated autophagy regulation, which suggested that O₂ ^·- was vital in this process. In conclusion, our results contribute to understanding the mechanism of ASIV-induced cardioprotective effect.

Astragalus species: Insights on its chemical composition toward pharmacological applications

Astragalus L. is widely distributed throughout the temperate regions of Europe, Asia, and North America. The genus is widely used in folk medicine and in dietary supplements, as well as in cosmetics, teas, coffee, vegetable gums, and as forage for animals. The major phytoconstituents of Astragalus species with beneficial properties are saponins, flavonoids, and polysaccharides. Astragalus extracts and their isolated components exhibited promising in vitro and in vivo biological activities, including antiaging, antiinfective, cytoprotective, antiinflammatory, antioxidant, antitumor, antidiabesity, and immune-enhancing properties. Considering their proven therapeutic potential, the aim of this work is to give a comprehensive summary of the Astragalus spp. and their active components, in an attempt to provide new insight for further clinical development of these xenobiotics. This is the first review that briefly describes their ethnopharmacology, composition, biological, and toxicological properties.

Astragaloside IV-targeting miRNA-1 attenuates lipopolysaccharide-induced cardiac dysfunction in rats through inhibition of apoptosis and autophagy

Astragaloside IV (AS-IV), the major active constituent purified from Astragalus membranaceus, was previously reported to have protective effects against cardiac dysfunction. However, the underlying mechanism remains unknown. In the present study, we investigated the protective effect of AS-IV on lipopolysaccharide (LPS)-induced cardiac dysfunction and explored the potential mechanism by focusing on miRNA-1 (miR-1) at the animal and cellular levels. A series of methods were used, including echocardiography, flow cytometry, ELISA, immunofluorescence, transmission electron microscopy, RT-PCR, and western blotting. The results showed that both AS-IV and the miR-1 inhibitor improved cardiac dysfunction, reduced heart injury, inhibited apoptosis and autophagy, and regulated the expression of calcium- and mitochondrial energy metabolism-related proteins in the heart tissue of rats treated with LPS. Importantly, AS-IV downregulated the expression of miR-1 mRNA in heart tissue. All effects of AS-IV were at least partly abolished by miR-1 mimics. In the in vitro study, both AS-IV and the miR-1 inhibitor inhibited apoptosis and autophagy and regulated the expression of calcium- and mitochondrial energy metabolism-related proteins in heart cells treated with LPS. Similarly, AS-IV downregulated the expression of miR-1 mRNA in heart cells. All effects of AS-IV on cells were at least partly abolished by miR-1 mimics. Furthermore, miR-1 mimics exhibited effects similar to LPS both in animal and cellular studies. Taken together, these results suggest that AS-IV protects against LPS-induced cardiac dysfunction by inhibiting calcium-mediated apoptosis and autophagy by targeting miR-1, highlighting a new mechanism for the therapeutic effect of AS-IV on cardiac dysfunction.

Phytochemistry and cardiovascular protective effects of Huang-Qi (Astragali Radix)

Huang-Qi (Astragali Radix) is an herbal tonic widely used in China and many other countries. It is derived from the roots of Astragalus membranaceus and A. membranaceus var. mongholicus and shows potent cardiovascular protective effects. In this article, we comprehensively reviewed 189 small molecules isolated from the two Astragalus species and discussed the interspecies chemical differences. Moreover, we summarized the pharmacological activities and mechanisms of action of Huang-Qi and its major bioactive compounds for the treatment of cardiovascular diseases. This review covers 171 references published between February 1983 and March 2020.

Saponins in Chinese Herbal Medicine Exerts Protection in Myocardial Ischemia-Reperfusion Injury: Possible Mechanism and Target Analysis

Myocardial ischemia is a high-risk disease among middle-aged and senior individuals. After thrombolytic therapy, heart tissue can potentially suffer further damage, which is called myocardial ischemia-reperfusion injury (MIRI). At present, the treatment methods and drugs for MIRI are scarce and cannot meet the current clinical needs. The mechanism of MIRI involves the interaction of multiple factors, and the current research hotspots mainly include oxidative stress, inflammation, calcium overload, energy metabolism disorders, pyroptosis, and ferroptosis. Traditional Chinese medicine (TCM) has multiple targets and few toxic side effects; clinical preparations containing Panax ginseng C. A. Mey., Panax notoginseng (Burk.) F. H. Chen, Aralia chinensis L., cardioprotection, and other Chinese herbal medicines have been used to treat patients with coronary heart disease, angina pectoris, and other cardiovascular diseases. Studies have shown that saponins are the main active substances in TCMs containing Panax ginseng C. A. Mey., Panax notoginseng (Burk.) F. H. Chen, Aralia chinensis L., and Radix astragali. In the present review, we sorted the saponin components with anti-MIRI effects and their regulatory mechanisms. Each saponin can play a cardioprotective role via multiple mechanisms, and the signaling pathways involved in different saponins are not the same. We found that more active saponins in Panax ginseng C. A. Mey. are mainly dammar-type structures and have a strong regulatory effect on energy metabolism. The highly active saponin components of Aralia chinensis L. are oleanolic acid structures, which have significant regulatory effects on calcium homeostasis. Therefore, saponins in Chinese herbal medicine provide a broad application prospect for the development of highly effective and low-toxicity anti-MIRI drugs.

The regulatory role of dietary factors in skeletal muscle development, regeneration and function

Skeletal muscle plays a crucial role in motor function, respiration, and whole-body energy homeostasis. How to regulate the development and function of skeletal muscle has become a hot research topic for improving lifestyle and extending life span. Numerous transcription factors and nutritional factors have been clarified are closely associated with the regulation of skeletal muscle development, regeneration and function. In this article, the roles of different dietary factors including green tea, quercetin, curcumin (CUR), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and resveratrol (RES) in regulating skeletal muscle development, muscle mass, muscle function, and muscle recovery have been summarized and discussed. We also reviewed the potential regulatory molecular mechanism of these factors. Based on the current findings, dietary factors may be used as a potential therapeutic agent to treat skeletal muscle dysfunction as well as its related diseases.

Astragaloside IV: An Effective Drug for the Treatment of Cardiovascular Diseases

Cardiovascular disease (CVD), the number one cause of death worldwide, has always been the focus of clinical and scientific research. Due to the high number of deaths each year, it is essential to find alternative therapies that are safe and effective with minimal side effects. Traditional Chinese medicine (TCM) has a long history of significant impact on the treatment of CVDs. The mode of action of natural active ingredients of drugs and the development of new drugs are currently hot topics in research on TCM. Astragalus membranaceus is a commonly used Chinese medicinal herb. Previous studies have shown that Astragalus membranaceus has anti-tumor properties and can regulate metabolism, enhance immunity, and strengthen the heart. Astragaloside IV (AS-IV) is the active ingredient of Astragalus membranaceus, which has a prominent role in cardiovascular diseases. AS-IV can protect against ischemic and hypoxic myocardial cell injury, inhibit myocardial hypertrophy and myocardial fibrosis, enhance myocardial contractility, improve diastolic dysfunction, alleviate vascular endothelial dysfunction, and promote angiogenesis. It can also regulate blood glucose and blood lipid levels and reduce the risk of cardiovascular diseases. In this paper, the mechanism of AS-IV intervention in cardiovascular diseases in recent years is reviewed in order to provide a reference for future research and new drug development.

Discovery of chemical markers for identifying species, growth mode and production area of Astragali Radix by using ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry

BACKGROUND

Astragali Radix (AR) is a well-known Chinese herbal medicine. The quality of AR can be affected by many factors such as species, growth mode and production area, but there are still no chemical markers to distinguish it.

PURPOSE

To explore chemical markers for improving the quality assessment of AR and discover chemical markers for identifying species, growth mode and production area of AR.

METHODS

A highly sensitive, efficient and accurate method based on ultra-high performance liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-QQQ-MS/MS) for simultaneous quantitative determination of 14 major chemical components (five flavonoids and nine triterpene saponins) in 94 batches of AR from China, Republic of Korea and Germany was developed for the first time. To explore chemical markers and assess changes in the contents of 14 compounds in the 94 batches of AR samples from different regions, hierarchical clustering analysis (HCA) and principal component analysis (PCA) were performed.

RESULTS

Astragaloside III was not only an important chemical marker for distinguishing two species of AR, i.e.: Astragalus mongholicus and A. membranaceus, but also a potential chemical marker for the classification of cultivated and semi-wild AR. In addition, in the batches of cultivated AR, the content of isoastragaloside II and cyclocephaloside II were greater in batches from the region of Shaanxi Province than that of other Provinces in China, but the content of calycosin-7-O-β-D-glucoside and astragaloside IV, which are the quality control markers of AR required by the Chinese Pharmacopoeia, were higher than that of other Provinces in China. In addition, the content of calycosin-7-O-β-D-glucoside, ononin, calycosin and astragaloside I could be used to identify samples of AR collected from China, Republic of Korea and Germany.

CONCLUSION

This UHPLC-QQQ-MS/MS method could be applied to the quantitative evaluation of AR and could be an important and meaningful reference to develop chemical markers for quality control of AR.

Astragaloside IV attenuates myocardial ischemia/reperfusion injury in rats via inhibition of calcium-sensing receptor-mediated apoptotic signaling pathways

Astragaloside IV (AsIV) is an active saponin extracted from Astragalus membranaceus, which has shown cardioprotective effects in a number of experimental animals. In this study we investigated the molecular mechanisms by which AsIV attenuated the myocardial ischemia reperfusion (MI/R)-induced injury in vitro and in vivo by focusing on calcium-sensing receptor (CaSR) and extracellular signal-regulated kinase 1/2 (ERK1/2). Rat neonatal cardiac myocytes were subjected to a hypoxia/reoxygenation (H/R) procedure in vitro, which significantly decreased the cell viability, increased lactate dehydrogenase (LDH) release, induced cardiomyocyte apoptosis, and increased [Ca²⁺]_i. H/R also increased the expression of CaSR and decreased ERK1/2 phosphorylation levels in H/R-exposed myocytes. Pretreatment with AsIV (60 μmol/L) significantly improved the cell viability and decreased LDH release, attenuated myocyte apoptosis, decreased [Ca²⁺]_i and CaSR expression, and increased the ERK1/2 phosphorylation levels. The protective effects of AsIV against H/R injury were partially inhibited by co-treatment with a CaSR agonist, gadolinium chloride (GdCl₃) or with a specific ERK1/2 inhibitor U0126. For in vivo studies, a rat MI/R model was established. Pre-administration of AsIV (80 mg/kg every day, ig) significantly decreased the myocardium infarct size, creatine kinase-MB (CK-MB) production, serum cardiac troponin (cTnI) levels, and cardiomyocyte apoptosis in the rats with MI/R injury. The therapeutic effects of AsIV were associated with the downregulation of CaSR expression and upregulation of ERK1/2 phosphorylation in myocardial tissues. In summary, astragaloside IV attenuates myocardial I/R injury via inhibition of CaSR/ERK1/2 and the related apoptotic signaling pathways.

In Vitro Neuroprotection of Rat Hippocampal Neurons by Manninotriose and Astragaloside IV Against Corticosterone-Induced Toxicity

A chronically elevated glucocorticoid level impairs memory and cognition. Manninotriose is the main oligosaccharide of Prepared Radix Rehmanniae, and Astragaloside IV (AS-IV) is the primary ingredient of Astragali Radix; they have been reported to possess neuroprotective effects. The aim of the present study was to investigate the protective effects of Manninotriose and AS-IV on corticosterone (CORT) induced neurotoxicity and the underlying mechanisms. Primary cultured hippocampal neurons from newborn Sprague Dawley rats were treated with CORT in the absence or presence of Manninotriose and AS-IV. Cell Counting Kit-8 experiments and fluorescein diacetate (FDA)/propidium iodide (PI) double staining were conducted to assess the activity and survival rate of neurons. Quantitative Real-time PCR (qRT-PCR) and western blot analysis were performed to detect the expression of glucocorticoid receptor (GR), zinc finger protein (Zif268) and synapsin 1 (SYN1). DNA methylation of the gene promoter was assessed by bisulfite sequencing (BSP) analysis. The results demonstrated that pre-treatment with Manninotriose and AS-IV significantly improved cell viability and survival rate, and ameliorated the downregulation of GR, Zif268 and SYN1 genes in CORT injured neurons. BSP analysis revealed that CORT was able to improve the CpG island methylation rate of SYN1. AS-IV was observed to decrease the hypermethylation of the SYN1 gene induced by CORT. The results of the present study indicated that Manninotriose and AS-IV may have a protective effect against CORT-induced damage and the downregulation of learning and memory associated genes in hippocampal neurons. Regulation of DNA methylation may be important in the pharmaceutical activities of AS-IV. Thus, Manninotriose and AS-IV may be effective agents against learning and memory impairment.

RETRACTED: Matrine inhibits hypoxia/reoxygenation-induced apoptosis of cardiac microvascular endothelial cells in rats via the JAK2/STAT3 signaling pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. An Expression of Concern for this article was previously published while an investigation was conducted (see related editorial: https://doi.org/10.1016/j.biopha.2022.113812). This retraction notice supersedes the Expression of Concern published earlier. Concerns were raised about the provenance of the flow cytometry data shown in Figure 5A, as detailed here: https://pubpeer.com/publications/46C8B5439C5C617A60494BA4C15479; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. Independent analysis also identified additional suspected image duplications between the Bax and Bcl-2 Western blots in Figure 6A. The journal requested the corresponding author comment on these concerns and provide the associated raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Astragalus Granule Prevents Ca2+ Current Remodeling in Heart Failure by the Downregulation of CaMKII

BACKGROUND

Astragalus was broadly used for treating heart failure (HF) and arrhythmias in East Asia for thousands of years. Astragalus granule (AG), extracted from Astragalus, shows beneficial effect on the treatment of HF in clinical research. We hypothesized that administration of AG prevents the remodeling of L-type Ca2+ current (ICa-L) in HF mice by the downregulation of Ca2+/calmodulin-dependent protein kinase II (CaMKII).

METHODS

HF mice were induced by thoracic aortic constriction (TAC). After 4 weeks of AG treatment, cardiac function and QT interval were evaluated. Single cardiac ventricular myocyte was then isolated and whole-cell patch clamp was used to record action potential (AP) and ICa-L. The expressions of L-type calcium channel alpha 1C subunit (Cav1.2), CaMKII, and phosphorylated protein kinase A (p-PKA) were examined by western blot.

RESULTS

The failing heart manifested distinct electrical remodeling including prolonged repolarization time and altered ICa-L kinetics. AG treatment attenuated this electrical remodeling, supported by AG-related shortened repolarization time, decreased peak ICa-L, accelerated ICa-L inactivation, and positive frequency-dependent ICa-L facilitation. In addition, AG treatment suppressed the overexpression of CaMKII, but not p-PKA, in the failing heart.

CONCLUSION

AG treatment protected the failing heart against electrical remodeling and ICa-L remodeling by downregulating CaMKII.

AstragalosideⅣ against cardiac fibrosis by inhibiting TRPM7 channel

BACKGROUND

Astragaloside Ⅳ (ASG-Ⅳ, (Fig. 1) is the most active component of Chinese sp. Astragalus membranaceus Bunge (Fabaceae) that has showed antioxidant, antiapoptotic and antiviral activities among others. It is reported to play an important role in cardiac fibrosis (CF), but the mechanism remains unclear.

PURPOSE

To investigate the mechanism of ASG-Ⅳ on inhibiting myocardial fibrosis induced by hypoxia.

STUDY DESIGN

We studied the relationship between anti-fibrotic effect of ASG-Ⅳ and transient receptor potential cation channel, subfamily M, member 7 (TRPM7) by in vivo and in vitro experiments.

METHODS

In vivo, CF was induced by subcutaneous isoproterenol (ISO) for 10 days. Rat hearts were resected for histological experiment and reverse transcription real-time quantitative poly merase chain reaction (RT-qPCR). In vitro, molecular and cellular biology technologies were used to confirm the anti-fibrosis effect underlying mechanism of ASG-Ⅳ.

RESULTS

Histological findings and the collagen volume fraction showed that ASG-Ⅳ decreased fibrosis in heart tissues. Hypoxia could stimulate the proliferation and differentiation of cardiac fibroblast which indicated that the degree of fibrosis was increased significantly. Anoxic treatment could also obviously up-regulate the expression of TRPM7 protein and current. ASG-Ⅳ groups showed the opposite results. Knock-down TRPM7 experiment further confirmed the role of TRPM7 channel in hypoxia-induced cardiac fibrosis.

CONCLUSION

Our results suggest that the inhibition of hypoxia-induced CF in vivo and in vitro by ASG-IV is associated with reduction of the expression of TRPM7. The moderate inhibition of the TRPM7 channel may be a new strategy for treating cardiac fibrosis.

The modified Yi qi decoction protects cardiac ischemia-reperfusion induced injury in rats

BACKGROUND

To investigate the effects and involved mechanisms of the modified Yi Qi decoction (MYQ) in cardiac ischemia-reperfusion (IR) induced injury.

METHODS

Male Sprague-Dawley rats were subjected to a 30-min coronary arterial occlusion followed by reperfusion, low or high dose decoction of MYQ was administrated orally for 1 week or 1 month.

RESULTS

Both in 1 week and 1 month IR rat groups, cardiac function indexes were significantly impaired compared with sham group rats, accompanied with higher ratio of infarct size to risk size, decreased expressions of sodium calcium exchanger (NCX1) and sarcoplasmic reticulum Ca2+-ATPase (Serca2a), and different expressions of autophagic proteins, Beclin-1 and LC3. Treatment with MYQ (low or high dose) for 1 week showed no marked beneficial effects on cardiac function and cardiac injury (ratio of infarct size to risk size), although expressions of anti-apoptotic protein, Bcl-2, NCX1 and Serca2a were increased. Treatment with MYQ (low or high dose) for 1 month showed significantly improved effects on cardiac function and cardiac injury (ratio of infarct size to risk size), accompanied with increase of Bcl-2, NCX1 and Serca2a expressions, and decrease of Bax (a pro-apoptotic protein) and Beclin-1 expressions.

CONCLUSIONS

The results show that MYQ have potential therapeutic effects on IR-induced cardiac injury, which may be through regulation of apoptotic proteins, cytosolic Ca2+ handling proteins and autophagic proteins signal pathways.

Astragaloside IV Attenuates Podocyte Apoptosis Mediated by Endoplasmic Reticulum Stress through Upregulating Sarco/Endoplasmic Reticulum Ca2+-ATPase 2 Expression in Diabetic Nephropathy

Sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) plays a central role in the pathogenesis of diabetes. This protein has been recognized as a potential target for diabetic therapy. In this study, we identified astragaloside IV (AS-IV) as a potent modulator of SERCA inhibiting renal injury in diabetic status. Increasing doses of AS-IV (2, 6, and 18 mg kg^-1 day^-1) were administered intragastrically to db/db mice for 8 weeks. Biochemical and histopathological approaches were conducted to evaluate the therapeutic effects of AS-IV. Cultured mouse podocytes were used to further explore the underlying mechanism in vitro. AS-IV dose-dependently increased SERCA activity and SERCA2 expression, and suppressed ER stress-mediated and mitochondria-mediated apoptosis in db/db mouse kidney. AS-IV also normalized glucose tolerance and insulin sensitivity, improved renal function, and ameliorated glomerulosclerosis and renal inflammation in db/db mice. In palmitate stimulated podocytes, AS-IV markedly improved inhibitions of SERCA activity and SERCA2 expression, restored intracellular Ca²⁺ homeostasis, and attenuated podocyte apoptosis in a dose-dependent manner with a concomitant abrogation of ER stress as evidenced by the downregulation of GRP78, cleaved ATF6, phospho-IRE1α and phospho-PERK, and the inactivation of both ER stress-mediated and mitochondria-mediated apoptotic pathways. Furthermore, SERCA2b knockdown eliminated the effect of AS-IV on ER stress and ER stress-mediated apoptotic pathway, whereas its overexpression exhibited an anti-apoptotic effect. Our data obtained from in vivo and in vitro studies demonstrate that AS-IV attenuates renal injury in diabetes subsequent to inhibiting ER stress-induced podocyte apoptosis through restoring SERCA activity and SERCA2 expression.

Targeted killing of myofibroblasts by biosurfactant di-rhamnolipid suggests a therapy against scar formation

Pathological myofibroblasts are often involved in skin scarring via generating contractile force and over-expressing collagen fibers, but no compound has been found to inhibit the myofibroblasts without showing severe toxicity to surrounding physiological cells. Here we report that di-rhamnolipid, a biosurfactant secreted by Pseudomonas aeruginosa, showed potent effects on scar therapy via a unique mechanism of targeted killing the myofibroblasts. In cell culture, the fibroblasts-derived myofibroblasts were more sensitive to di-rhamnolipid toxicity than fibroblasts at a concentration-dependent manner, and could be completely inhibited of their specific functions including α-SMA expression and collagen secretion/contraction. The anti-fibrotic function of di-rhamnolipid was further verified in rabbit ear hypertrophic scar models by presenting the significant reduction of scar elevation index, type I collagen fibers and α-SMA expression. In this regard, di-rhamnolipid treatment could be suggested as a therapy against skin scarring.

Research review on the pharmacological effects of astragaloside IV

Astragalus membranaceus Bunge has been used to treat numerous diseases for thousands of years. As the main active substance of Astragalus membranaceus Bunge, astragaloside IV (AS-IV) also demonstrates the potent protective effect on focal cerebral ischemia/reperfusion, cardiovascular disease, pulmonary disease, liver fibrosis, and diabetic nephropathy. Based on studies published during the past several decades, the current state of AS-IV research and the pharmacological effects are detailed, elucidated, and summarized. This review systematically summarizes the pharmacological effects, metabolism mechanism, and the toxicity of AS-IV. AS-IV has multiple pharmacologic effects, including anti-inflammatory, antifibrotic, antioxidative stress, anti-asthma, antidiabetes, immunoregulation, and cardioprotective effect via numerous signaling pathways. According to the existing studies and clinical practices, AS-IV possesses potential for broad application in many diseases.

Protective Effects of Danlou Tablet () against Murine Myocardial Ischemia and Reperfusion Injury In Vivo

OBJECTIVE

To observe the in vivo effect of Danlou Tablet (, DLT) on myocardial ischemia and reperfusion (I/R) injury.

METHODS

DLT effects were evaluated in mouse heart preparation using 30-min coronary occlusion followed by 24-h reperfusion and compared among sham group (n=6), I/R group (n=8), IPC group (ischemia preconditioning, n=6) and DLT group (I/R with DLT pretreatment for 3 days, 750 mg•kg^-1•day^-1, n=8). The effects of DLT were characterized in infarction size (IS) compared with risk region (RR) and left ventricle using the Evans blue/triphenyltetrazolium chloride double dye staining method in vivo. Furthermore, the dose-dependent effect of DLT on I/R injury was evaluated by double staining method. Five different concentrations of DLT (0.625, 1.25, 2.5, 5 and 10 g•kg^-1•day^-1) were chosen in this study, and dose-response curve of DLT was obtained on these data.

RESULTS

The ratio of IS to left ventricle was significantly smaller in the DLT and IPC groups than the I/R group (P<0.05 or P<0.01), the ratio of IS to RR was also reduced in the DLT and IPC groups (P<0.01), while there were no differences in RR among the four groups (P>0.05). Experiments showed incidence of arrhythmias was reduced in the DLT group (P<0.01). Furthermore, DLT produced a dose-dependent inhibitory effect with a half maximal inhibitory concentration of 1.225 g•kg^-1•day^-1.

CONCLUSIONS

Our research concluded that DLT was effective in reducing I/R injury in mice, and provided experimental supports for the clinical use of DLT.

YiXin-Shu, a ShengMai-San-based traditional Chinese medicine formula, attenuates myocardial ischemia/reperfusion injury by suppressing mitochondrial mediated apoptosis and upregulating liver-X-receptor α

Positive evidence from clinical trials has fueled growing acceptance of traditional Chinese medicine (TCM) for the treatment of cardiac diseases; however, little is known about the underlying mechanisms. Here, we investigated the nature and underlying mechanisms of the effects of YiXin-Shu (YXS), an antioxidant-enriched TCM formula, on myocardial ischemia/reperfusion (MI/R) injury. YXS pretreatment significantly reduced infarct size and improved viable myocardium metabolism and cardiac function in hypercholesterolemic mice. Mechanistically, YXS attenuated myocardial apoptosis by inhibiting the mitochondrial mediated apoptosis pathway (as reflected by inhibition of mitochondrial swelling, cytochrome c release and caspase-9 activity, and normalization of Bcl-2 and Bax levels) without altering the death receptor and endoplasmic reticulum-stress death pathways. Moreover, YXS reduced oxidative/nitrative stress (as reflected by decreased superoxide and nitrotyrosine content and normalized pro- and anti-oxidant enzyme levels). Interestingly, YXS upregulated endogenous nuclear receptors including LXRα, PPARα, PPARβ and ERα, and in-vivo knockdown of cardiac-specific LXRα significantly blunted the cardio-protective effects of YXS. Collectively, these data show that YXS is effective in mitigating MI/R injury by suppressing mitochondrial mediated apoptosis and oxidative stress and by upregulating LXRα, thereby providing a rationale for future clinical trials and clinical applications.

Total glycosides of Ranunculus japonius prevent hypertrophy in cardiomyocytes via alleviating chronic Ca(2+) overload

OBJECTIVE

To evaluate the in vitro anti-hypertrophic effect of total Glycosides of Ranunculus Japonius (TGRJ).

METHODS

Neonatal rat cardiomyocytes were cultured and hypertrophy was induced by administrating isoproterenol (ISO, 10 µmol/L) or angiotensin 2 (Ang 2, 1 µmol/L) for 48 hours. In the treatment groups, cells were pretreated with TGRJ (0.3 g/L) for 30 minutes prior to hypertrophic stimuli. The anti-hypertrophic effects of TGRJ were examined by measuring cell size, total protein content, and protein synthesis. Intracellular free Ca(2+) concentration ([Ca(2+)]i) was evaluated using fluorescence dye Fura-2/AM. Sacroplasmic/endoplasmic reticulum Ca(2+) ATPase 2a (SERCA2a), atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and beta-myosin heavy chain (β-MHC) protein expression levels were measured by Western blotting . SERCA2a activity was assayed by p-nitrophenal phosphate disodium salt hexahydrate method.

RESULTS

Increased cell size, total protein content, and protein synthesis following ISO or Ang 2 stimulation were significantly inhibited by pretreatment with TGRJ (all P<0.05). This anti-hypertrophic effect of TGRJ was confirmed by its suppressing effect on elevated expression of the three hypertrophic related genetic markers, ANP, BNP, and β-MHC. In addition, TGRJ inhibited ISO or Ang 2 induced up-regulation of [Ca(2+)]i under chronic but not acute conditions. And ISO or Ang 2 induced down-regulation of SERCA2a expression and activity was also effectively rectified by TGRJ pretreatment.

CONCLUSIONS

The results of present study suggested that TGRJ could prevent ISO or Ang 2 induced cardiac hypertrophy through improving chronic [Ca(2+)]i disorder, might via normalizing SERCA2a expression and activity.

Effect of astragaloside IV against rat myocardial cell apoptosis induced by oxidative stress via mitochondrial ATP-sensitive potassium channels

Astragaloside is one of the most common traditional Chinese medicines and is derived from Astragalus membranaceus. Astragaloside IV (AsIV) is a monomer located in an extract of astragaloside. The current study investigated the protective effects of AsIV against hydrogen peroxide (H2O2)-induced injury in cardiocytes and elucidated the mechanisms responsible for this protective effect. Cultured neonatal rat cardiocytes were divided into five experimental groups as follows: i) Dimethyl sulfoxide; ii) H2O2; iii) AsIV+H2O2; iv) AsIV+H2O2+5-hydroxydecanoate (5-HD); and v) nicorandil+H2O2. Cardiocyte survival was analyzed using an MTT assay. Lactate dehydrogenase (LDH) release was also assessed to evaluate the viability of the cells. Intracellular reactive oxygen species (ROS) were measured by 2,7-dichlorodihydrofluorescein diacetate staining. The apoptotic rate was measured by flow cytometry. Mitochondrial membrane potential (ΔΨm) and intracellular calcium were observed using a laser confocal microscopy system. The results indicated that AsIV promoted the survival of cardiocytes (P<0.05), attenuated LDH release (P<0.05), ROS production (P<0.01) and apoptosis (P<0.01), stabilized the ΔΨm and reduced intracellular calcium overload (P<0.01) compared with the H2O2 group. The mitochondrial adenosine triphosphate-sensitive potassium channel (mitoKATP) inhibitor 5-HD was observed to partially reverse the protective effect of AsIV. Following treatment with 5-HD, the survival of cardiocytes was reduced (P<0.05), LDH release (P<0.01) and ROS production (P<0.05) were stimulated, ΔΨm and intracellular calcium change were increased (P<0.01) and apoptosis was increased (P<0.01) compared with the AsIV+H2O2 group. Thus, AsIV has potential for use in the suppression of apoptosis resulting from H2O2 exposure, and mitoKATP activation may underlie this protective mechanism.

Astragaloside IV attenuates injury caused by myocardial ischemia/reperfusion in rats via regulation of toll-like receptor 4/nuclear factor-κB signaling pathway

Myocardial ischemia/reperfusion (MI/R) injury, in which inflammatory response and cell apoptosis play a vital role, is frequently encountered in clinical practice. Astragaloside IV (AsIV), a small molecular saponin of Astragalus membranaceus, has been shown to confer protective effects against many cardiovascular diseases. The present study was aimed to investigate the antiinflammatory and antiapoptotic effects and the possible mechanism of AsIV on MI/R injury in rats. Rats were randomly divided into sham operation group, MI/R group and groups with combinations of MI/R and different doses of AsIV. The results showed that the expressions of myocardial toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) were significantly increased, and apoptosis of cardiomyocytes was induced in MI/R group compared with that in sham operation group. Administration of AsIV attenuated MI/R injury, downregulated the expressions of TLR4 and NF-κB and inhibited cell apoptosis as evidenced by decreased terminal deoxynucleotidyl transferase dUTP nick end labeling positive cells, B-cell lymphoma-2 associated X protein and caspase-3 expressions and increased B-cell lymphoma-2 expression compared with that in MI/R group. In addition, AsIV treatment reduced levels of inflammatory cytokines induced by MI/R injury. In conclusion, our results demonstrated that AsIV downregulates TLR4/NF-κB signaling pathway and inhibits cell apoptosis, subsequently attenuating MI/R injury in rats.

Relationships between chemical structures and functions of triterpene glycosides isolated from sea cucumbers

Many marine triterpene glycosides have in vitro and in vivo activities with very low toxicity, suggesting that they are suitable agents for the prevention and treatment of different diseases, particularly cancer. However, the molecular mechanisms of action of natural marine compounds in cancer, immune, and other various cells are not fully known. This review focuses on the structural characteristics of marine triterpene glycosides and how these affect their biological activities and molecular mechanisms. In particular, the membranotropic and membranolytic activities of frondoside A and cucumariosides from sea cucumbers and their ability to induce cytotoxicity and apoptosis have been discussed, with a focus on structure-activity relationships. In addition, the structural characteristics and antitumor effects of stichoposide C and stichoposide D have been reviewed along with underlying their molecular mechanisms.

SPRC protects hypoxia and re-oxygenation injury by improving rat cardiac contractile function and intracellular calcium handling

S-Propargyl-L-cysteine (SPRC, also named as ZYZ-802) is a new compound synthesized in our lab. We investigated whether SPRC has exerted protective effects against cardiac hypoxia/re-oxygenation (H/R) and also explored its mechanisms. In our study, isolated ventricular myocytes were subject to a simulated hypoxia solution for 30 min to induce cell injury. Intracellular concentration of Ca(2+) ([Ca(2+)]i) was measured using specific dyes and detected by digital imaging apparatus. Apoptotic cells were evaluated by TUNEL assay. Intervention with SPRC (10 μM) 30 min before hypoxia, can significantly attenuate the apoptosis of isolated papillary muscles resulting from the H/R injury and protect morphology of the muscles. In isolated ventricular myocytes, SPRC considerably improved left ventricular functional recovery. SPRC also suppressed the increase of ([Ca(2+)]i) during hypoxia stage. By measuring the calcium transient of the cell we concluded that SPRC can preserve the RyR and SERCA activities and improve Ca(2+) handling during the H/R. Furthermore, the protective effect of SPRC can be partly blocked by CSE inhibitor PAG.

Astragalus membranaceus improves exercise performance and ameliorates exercise-induced fatigue in trained mice

Astragalus membranaceus (AM) is a popular "Qi-tonifying" herb with a long history of use as a Traditional Chinese Medicine with multiple biological functions. However, evidence for the effects of AM on exercise performance and physical fatigue is limited. We evaluated the potential beneficial effects of AM on ergogenic and anti-fatigue functions following physiological challenge. Male ICR strain mice were randomly assigned to four groups (n = 10 per group) for treatment: (1) sedentary control and vehicle treatment (vehicle control); (2) exercise training with vehicle treatment (exercise control); and (3) exercise training with AM treatment at 0.615 g/kg/day (Ex-AM1) or (4) 3.075 g/kg/day (Ex-AM5). Both the vehicle and AM were orally administered for 6 weeks. Exercise performance and anti-fatigue function were evaluated by forelimb grip strength, exhaustive swimming time, and levels of serum lactate, ammonia, glucose, and creatine kinase after 15-min swimming exercise. Exercise training combined with AM supplementation increased endurance exercise capacity and increased hepatic and muscle glycogen content. AM reduced exercise-induced accumulation of the byproducts blood lactate and ammonia with acute exercise challenge. Moreover, we found no deleterious effects from AM treatment. Therefore, AM supplementation improved exercise performance and had anti-fatigue effects in mice. It may be an effective ergogenic aid in exercise training.

Effects of salvianolic acid and notoginseng triterpenes on angiogenesis in EA-hy926 cells in vitro

AIM

To investigate the different effects of salvianolic acid and notoginseng triterpenes on proliferation, angiogenesis and expression of vascular endothelial growth factor in EA-hy926 cells in vitro.

METHODS

EA-hy926 cells were cultured in vitro. Salvianolic acid and notoginseng triterpenes at concentrations of 0.4, 0.8 and 1.2 mg·L(-1) were used to culture EA-hy926 cells. EA-hy926 cells in a blank control group were grown in culture solution only. Viability of cells was assessed by CCK-8, and after treated for 12 h, capillary-like structures were examined. After 24 h culture, the expression of VEGF was detected by real-time PCR.

RESULTS

Salvianolic acid at 0.4, 0.8 mg·L(-1), the same as notoginseng triterpenes, increased VEGF content in EA-hy926 cells. Expression of VEGF protein in the salvianolic acid at 1.2 mg·L(-1) group, was up-regulated as compared with notoginseng triterpenes group (P < 0.05).

CONCLUSION

Salvianolic acid and notoginseng triterpenes can promote EA-hy926 cell proliferation, angiogenesis and expression of VEGF protein. This analysis also provided evidence that salvianolic acid had the better effects as compared with notoginseng triterpenes.

Effects of astragaloside IV on action potentials and ionic currents in guinea-pig ventricular myocytes

Astragaloside IV (AS-IV) is one of the main active constituents of Astragalus membranaceus, which has various actions on the cardiovascular system. However, its electrophysiological mechanisms are not clear. In the present study, we investigated the effects of AS-IV on action potentials and membrane currents using the whole-cell patch clamp technique in isolated guinea-pig ventricular myocytes. AS-IV prolonged the action potential duration (APD) at all three tested concentrations. The peak effect was achieved with 1×10(-6) M, at which concentration AS-IV significantly prolonged the APD at 95% repolarization from 313.1±38.9 to 785.3±83.7 ms. AS-IV at 1×10(-6) M also enhanced the inward rectifier K(+) currents (I(K1)) and inhibited the delayed rectifier K(+) currents (I(K)). AS-IV (1×10(-6) M) strongly depressed the peak of voltage-dependent Ca(2+) channel current (I(CaL)) from -607.3±37.5 to -321.1±38.3 pA. However, AS-IV was not found to affect the Na(+) currents. Taken together, AS-IV prolonged APD of guinea-pig ventricular myocytes, which might be explained by its inhibition of I(K). AS-IV also influences Ca(2+) signaling through suppressing ICaL.

Tongguan Capsule Protects against Myocardial Ischemia and Reperfusion Injury in Mice

Myocardial ischemia/reperfusion (I/R) can induce lethal ventricular arrhythmia and myocardial infarction. One of the clinical strategies for managing patients with high risk of myocardial I/R is to prevent the occurrence of arrhythmias and limit the size of infarction following a coronary episode. Tongguan Capsule (TGC) is one of the popular herbal remedies in treating coronary artery disease in the clinics of Chinese medicine. However, the potential roles and mechanisms of TGC in reducing I/R injury are still unclear. The present study statistically assessed the effectiveness of TGC in reducing I/R injury by comparing the infarct size (IS), risk region (RR), and arrhythmia (in electrocardiogram) among four groups of surgically created mice models of myocardial I/R: SHAM, I/R, VER (I/R with verapamil 20 mg/kg pretreatment), and TGC (I/R with TGC 5 g/kg/d pretreatment). We found that IS was significantly smaller in the TGC and VER groups than I/R group, and the incidence of arrhythmias was reduced in the TGC group compared with I/R group, although there were no differences in RR among the four groups. We conclude that TGC is effective in reducing I/R injury in mice. These results provided an experimental basis for clinical application of TGC in reducing I/R injury.

Growth hormone secretagogues preserve the electrophysiological properties of mouse cardiomyocytes isolated from in vitro ischemia/reperfusion heart

Ischemic heart diseases often induce cardiac arrhythmia with irregular cardiac action potential (AP). This study aims to demonstrate that GH secretagogues (GHS) ghrelin and its synthetic analog hexarelin can preserve the electrophysiological properties of cardiomyocytes experiencing ischemia/reperfusion (I/R). Isolated hearts from adult male mice underwent 20 min global ischemia followed by 30 min reperfusion using a Langendorff apparatus. Ghrelin (10 nM) or hexarelin (1 nM) was administered in the perfusion solution either 10 min before or after ischemia, termed pre- or posttreatments. Cardiomyocytes isolated from these hearts were used for whole-cell patch clamping to measure AP, voltage-gated L-type calcium current (I(CaL)), transient outward potassium current (I(to)), and sodium current (I(Na)). AP amplitude and duration were significantly decreased by I/R, but GHS treatments maintained their normality. GHS treatments prevented the decrease in I(CaL) and I(Na) after I/R, thereby maintaining AP amplitude. Although the significant increase in I(to) after I/R partially explained the shortened AP duration, the normalization of it by GHS treatments might contribute to the preservation of AP duration. Phosphorylated p38 and c-Jun NH(2)-terminal kinase and the downstream active caspase-9 in the cellular apoptosis pathway were significantly increased after I/R but not when GHS treatments were included, whereas phosphorylation of ERK1/2 associated with cell survival showed increase after I/R and a further increase after GHS treatments by binding to its receptor GHS receptor type 1a. These results suggest GHS can not only preserve the electrophysiological properties of cardiomyocytes after I/R but also inhibit cardiomyocyte apoptosis and promote cell survival by modification of MAPK pathways through activating GHS receptor type 1a.

Astragaloside IV inhibits oxidative stress-induced mitochondrial permeability transition pore opening by inactivating GSK-3β via nitric oxide in H9c2 cardiac cells

Objective. This study aimed to investigate whether astragaloside IV modulates the mitochondrial permeability transition pore (mPTP) opening through glycogen synthase kinase 3β (GSK-3β) in H9c2 cells. Methods. H9c2 cells were exposed to astragaloside IV for 20 min. GSK-3β (Ser⁹), Akt (Ser⁴⁷³), and VASP (Ser²³⁹) activities were determined with western blot. The mPTP opening was evaluated by measuring mitochondrial membrane potential (ΔΨ_m). Nitric oxide (NO) generation was measured by 4-amino-5-methylamino-2′, 7′-difluorofluorescein (DAF-FM) diacetate. Fluorescence images were obtained with confocal microscopy. Results. Astragaloside IV significantly enhanced GSK-3β phosphorylation and prevented H₂O₂-induced loss of ΔΨ_m. These effects of astragaloside IV were reversed by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002, the NO sensitive guanylyl cyclase selective inhibitor ODQ, and the PKG inhibitor KT5823. Astragaloside IV activated Akt and PKG. Astragaloside IV was also shown to increase NO production, an effect that was reversed by L-NAME and LY294002. Astragaloside IV applied at reperfusion reduced cell death caused by simulated ischemia/reperfusion, indicating that astragaloside IV can prevent reperfusion injury. Conclusions. These data suggest that astragaloside IV prevents the mPTP opening and reperfusion injury by inactivating GSK-3β through the NO/cGMP/PKG signaling pathway. NOS is responsible for NO generation and is activated by the PI3K/Akt pathway.

Ginkgo biloba extract EGB761 protects against aging-associated diastolic dysfunction in cardiomyocytes of D-galactose-induced aging rat

The aim of the present study was to make use of the artificially induced aging model cardiomyocytes to further investigate potential anti-aging-associated cellular diastolic dysfunction effects of EGB761 and explore underlying molecular mechanisms. Cultured rat primary cardiomyocytes were treated with either D-galactose or D-galactose combined with EGB761 for 48 h. After treatment, the percentage of cells positive for SA-β-gal, AGEs production, cardiac sarcoplasmic reticulum calcium pump (SERCA) activity, the myocardial sarcoplasmic reticulum calcium uptake, and relative protein levels were measured. Our results demonstrated that in vitro stimulation with D-galactose induced AGEs production. The addition of EGB761 significantly decreased the number of cells positive for SA-β-gal. Furthermore, decreased diastolic [Ca²⁺]_i, curtailment of the time from the maximum concentration of Ca²⁺ to the baseline level and increased reuptake of Ca²⁺ stores in the SR were also observed. In addition, the level of p-Ser16-PLN protein as well as SERCA was markedly increased. The study indicated that EGb761 alleviates formation of AGEs products on SERCA2a in order to mitigate myocardial stiffness on one hand; on other hand, improve SERCA2a function through increase the amount of Ser16 sites PLN phosphorylation, which two hands finally led to ameliorate diastolic dysfunction of aging cardiomyocytes.

Mesencephalic astrocyte-derived neurotrophic factor protects the heart from ischemic damage and is selectively secreted upon sarco/endoplasmic reticulum calcium depletion

The endoplasmic reticulum (ER) stress protein mesencephalic astrocyte-derived neurotrophic factor (MANF) has been reported to protect cells from stress-induced cell death before and after its secretion; however, the conditions under which it is secreted are not known. Accordingly, we examined the mechanism of MANF release from cultured ventricular myocytes and HeLa cells, both of which secrete proteins via the constitutive pathway. Although the secretion of proteins via the constitutive pathway is not known to increase upon changes in intracellular calcium, MANF secretion was increased within 30 min of treating cells with compounds that deplete sarcoplasmic reticulum (SR)/ER calcium. In contrast, secretion of atrial natriuretic factor from ventricular myocytes was not increased by SR/ER calcium depletion, suggesting that not all secreted proteins exhibit the same characteristics as MANF. We postulated that SR/ER calcium depletion triggered MANF secretion by decreasing its retention. Consistent with this were co-immunoprecipitation and live cell, zero distance, photo affinity cross-linking, demonstrating that, in part, MANF was retained in the SR/ER via its calcium-dependent interaction with the SR/ER-resident protein, GRP78 (glucose-regulated protein 78 kDa). This unusual mechanism of regulating secretion from the constitutive secretory pathway provides a potentially missing link in the mechanism by which extracellular MANF protects cells from stresses that deplete SR/ER calcium. Consistent with this was our finding that administration of recombinant MANF to mice decreased tissue damage in an in vivo model of myocardial infarction, a condition during which ER calcium is known to be dysregulated, and MANF expression is induced.

Growth hormone secretagogues protect mouse cardiomyocytes from in vitro ischemia/reperfusion injury through regulation of intracellular calcium

Background

Ischemic heart disease is a leading cause of mortality. To study this disease, ischemia/reperfusion (I/R) models are widely used to mimic the process of transient blockage and subsequent recovery of cardiac coronary blood supply. We aimed to determine whether the presence of the growth hormone secretagogues, ghrelin and hexarelin, would protect/improve the function of heart from I/R injury and to examine the underlying mechanisms.

Methodology/Principal Findings

Isolated hearts from adult male mice underwent 20 min global ischemia and 30 min reperfusion using a Langendorff apparatus. Ghrelin (10 nM) or hexarelin (1 nM) was introduced into the perfusion system either 10 min before or after ischemia, termed pre- and post-treatments. In freshly isolated cardiomyocytes from these hearts, single cell shortening, intracellular calcium ([Ca²⁺]_i) transients and caffeine-releasable sarcoplasmic reticulum (SR) Ca²⁺ were measured. In addition, RT-PCR and Western blots were used to examine the expression level of GHS receptor type 1a (GHS-R1a), and phosphorylated phospholamban (p-PLB), respectively. Ghrelin and hexarelin pre- or post-treatments prevented the significant reduction in the cell shortening, [Ca²⁺]_i transient amplitude and caffeine-releasable SR Ca²⁺ content after I/R through recovery of p-PLB. GHS-R1a antagonists, [D-Lys3]-GHRP-6 (200 nM) and BIM28163 (100 nM), completely blocked the effects of GHS on both cell shortening and [Ca²⁺]_i transients.

Conclusion/Significance

Through activation of GHS-R1a, ghrelin and hexarelin produced a positive inotropic effect on ischemic cardiomyocytes and protected them from I/R injury probably by protecting or recovering p-PLB (and therefore SR Ca²⁺ content) to allow the maintenance or recovery of normal cardiac contractility. These observations provide supporting evidence for the potential therapeutic application of ghrelin and hexarelin in patients with cardiac I/R injury.

Determination of astragalin and astragaloside content in Radix Astragali using high-performance liquid chromatography coupled with pulsed amperometric detection

Astragalin and astragalosides were measured in Radix Astragali using reversed-phase chromatography coupled with pulsed amperometric detection. Because the target compounds showed poor stability in aqueous solutions, they were extracted in 100% methanol under reflux. All compounds were detected with high sensitivity under highly alkaline conditions using sodium hydroxide as a post-column eluent. The limits of detection and quantification of target compounds were 0.02-0.36 μg/mL and 0.06-1.09 μg/mL, respectively, and the linear regression coefficients were 0.9982-1.0000. The intra- and inter-day precisions were <0.92% in retention time and <4.78% in calculated contents. Average recoveries were >91.33%. Astragalin and astragaloside contents between Radix Astragali at different ages and in different parts were successfully determined without sample purification or concentration.

Astragaloside IV synergizes with ferulic acid to inhibit renal tubulointerstitial fibrosis in rats with obstructive nephropathy

BACKGROUND AND PURPOSE

The combination of Chinese herbs, Astragali Radix and Angelicae Sinensis Radix, could alleviate renal interstitial fibrosis. Astragaloside IV (AS-IV) and ferulic acid (FA) are the two major active constituents in this combination. In this study, we employed rats with unilateral ureteral obstruction to determine whether AS-IV and FA have the same renoprotective effects and investigated the mechanisms of this action.

EXPERIMENTAL APPROACH

Renal pathological changes were evaluated after treatment with AS-IV, FA or AS-IV + FA (AF) for 10 days. Meanwhile, the expression of transforming growth factor β₁ (TGF-β₁), fibronectin, α-smooth muscle actin (α-SMA), phosphorylation of c-Jun NH₂-terminal kinase (p-JNK) and nitric oxide (NO) production in kidney were determined. The expressions of fibronectin, α-SMA, mitogen-activated protein kinases [JNK, extracellular signal-regulated kinases (ERK), P38] in TGF-β₁-treated NRK-49F cells or interleukin-1-treated HK-2 cells after AS-IV, FA or AF were assessed.

KEY RESULTS

AF alleviated the infiltration of mononuclear cells, tubular atrophy and interstitial fibrosis; reduced the expression of fibronectin, α-SMA, TGF-β₁ and p-JNK; and dramatically increased the production of NO in obstructed kidneys. Neither AS-IV nor FA alone improved renal damage, but both increased NO production. AF inhibited α-SMA and fibronectin expression in NRK-49F or HK-2 cells. Furthermore, AF significantly inhibited IL-1β-induced JNK phosphorylation, without affecting ERK or P38 phosphorylation. Neither AS-IV nor FA alone had any effect on the cells.

CONCLUSIONS AND IMPLICATIONS

AS-IV synergizes with FA to alleviate renal tubulointerstitial fibrosis; this was associated with inhibition of tubular epithelial–mesenchymal transdifferentiation (EMT) and fibroblast activation, as well as an increase in NO production in the kidney.