miR-432 exerts a protective effect against myocardial ischemia/reperfusion injury by activating the ß-catenin/HIF-1α pathway and augmenting NRF2-mediated anti-oxidative stress.

OBJECTIVE: MicroRNAs (miRNAs) have been shown to play an important role in myocardial ischemia/reperfusion (MI/R) injury. This study aimed to determine the role of miR-432 in MI/R injury. METHODS: We established a MI/R injury model by ligation/untying of the left anterior descending coronary artery, and used viral infection to regulate gene expression, such as that of miR-432 in vitro and in vivo, and used RT-qPCR to detect the expression of the gene at mRNA level. Finally, western blotting and immunochemistry analyses were used to determine the protein level. RESULTS: The results of this study show that miR-432 is upregulated in the heart following MI/R injury and that miR-432 overexpression showed a significant decrease, while miR-432 knockdown showed a significant increase in the ratio of the infarct area (IA) to the area at risk (AAR) and levels of serum creating phosphokinase (CPK). Moreover, miR-432 augmented the activation of the ß-catenin pathway and decreased the rate of apoptosis in the mice heart at 24 hours after MI/R injury by targeting RBM5. At the same time, miR-432 overexpression enhanced HIF-1α activation, while ß-catenin deletion attenuated HIF-1α activation induced by miR-432 overexpression. Importantly, ß-catenin and HIF-1α knockdown significantly increased the rate of apoptosis and the ratio of IA to AAR and levels of serum CPK induced by miR-432 overexpression at 24 hours after MI/R injury. miR-432 overexpression strongly decreased levels of SOD and GSH-PX activity, and increased levels of MDA activity and the expression of the gp91phox protein in the mice hearts at 24 hours after MI/R injury, while miR-432 knockdown exerted an opposite effect. miR-432 was also found to have increased NRF2 protein levels by targeting KEAP1 protein expression. NRF2 knockdown reversed the downregulation of the levels of gp91phox protein and MDA, while it also reversed the upregulation of the levels of SOD and GSH-PX induced by miR-432 overexpression in the heart of the mice at 24 hours after MI/R injury. CONCLUSION: miR-432 protects against MI/R injury by activating the ß-catenin/HIF-1α pathway and augmenting NRF2-mediated anti-oxidative stress.

Nesfatin-1 inhibits myocardial ischaemia/reperfusion injury through activating Akt/ERK pathway-dependent attenuation of endoplasmic reticulum stress.

Nesfatin-1 (encoded by NUCB2) is a cardiac peptide possessing protective activities against myocardial ischaemia/reperfusion (MI/R) injury. However, the regulation of NUCB2/nesfatin-1 and the molecular mechanisms underlying its roles in MI/R injury are not clear. Here, by investigating a mouse MI/R injury model developed with transient myocardial ischaemia followed by reperfusion, we found that the levels of NUCB2 transcript and nesfatin-1 amount in the heart were both decreased, suggesting a transcriptional repression of NUCB2/nesfatin-1 in response to MI/R injury. Moreover, cardiac nesfatin-1 restoration reduced infarct size, troponin T (cTnT) level and myocardial apoptosis, supporting its cardioprotection against MI/R injury in vivo. Mechanistically, the Akt/ERK pathway was activated, and in contrast, endoplasmic reticulum (ER) stress was attenuated by nesfatin-1 following MI/R injury. In an in vitro system, similar results were obtained in nesfatin-1-treated H9c2 cardiomyocytes with hypoxia/reoxygenation (H/R) injury. More importantly, the treatment of wortmannin, an inhibitor of Akt/ERK pathway, abrogated nesfatin-1 effects on attenuating ER stress and H/R injury in H9c2 cells. Furthermore, nesfatin-1-mediated protection against H/R injury also vanished in the presence of tunicamycin (TM), an ER stress inducer. Lastly, Akt/ERK inhibition reversed nesfatin-1 effects on mouse ER stress and MI/R injury in vivo. Taken together, these findings demonstrate that NUCB2/nesfatin-1 inhibits MI/R injury through attenuating ER stress, which relies on Akt/ERK pathway activation. Hence, our study provides a molecular basis for understanding how NUCB2/nesfatin-1 reduces MI/R injury.

Arctigenin Attenuates Ischemia/Reperfusion Induced Ventricular Arrhythmias by Decreasing Oxidative Stress in Rats.

BACKGROUND/AIMS: Arctigenin (ATG) has been shown to possess anti-inflammatory, immunemodulatory, anti-viral, anti-microbial, anti-carcinogenic, vasodilatory and anti-platelet aggregation properties. However, the protective role of ATG in prevention of arrhythmias induced by myocardial ischemia/reperfusion is unknown. The aim of this study was to investigate the anti-arrhythmia effect of ATG in an ischemia/reperfusion injured rat heart model and explore the related mechanisms. METHODS: Rats were randomly exposed to sham operation, myocardial ischemia/ reperfusion (MI/R) alone, ATG+ MI/R, pretreated with ATG in low (12.5 mg/kg/day), medium (50 mg/kg/day) and high dose (200 mg/kg/day), respectively. Ventricular arrhythmias were assessed. The activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the level of malondialdehyde (MDA) in myocardial tissue were determined by chemical analysis. RESULTS: Compared to MI/R, rats pretreated with ATG in doses of 50 mg/kg/day and 200 mg/kg/day showed significantly reduced incidence and duration of ventricular fibrillation, ventricular tachycardia and ventricular ectopic beat (VEB), and decreased the arrhythmia score during the 30-min ischemia. Incidence and duration of ventricular tachycardia, infarction size and arrhythmia scores in these groups were significantly decreased during the 120-min reperfusion. No ventricular fibrillation occurred during the period of reperfusion. Rats pretreated with ATG in doses of 50 mg/kg/day and 200 mg/kg/ day markedly enhanced the activities of antioxidant enzymes SOD and GSH-Px, reduced the level of MDA. No differences were observed between the group pretreated with a low dose of ATG and the sham group. Administration of ATG significantly increased the expression of antioxidant stress protein Nrf2, Trx1 and Nox1. CONCLUSION: Our data suggested that ATG plays anti-arrhythmia role in ischemia/reperfusion injury, which is probably associated with attenuating oxidative stress by Nrf2 signaling pathway.

Nicotine-induced ICAM-1 and VCAM-1 expression in mouse cardiac vascular endothelial cell via p38 MAPK signaling pathway.

OBJECTIVE: To explore the link between cigarette smoking and thromboembolic events and to investigate cigarette smoking as a major risk factor in the etiology of atherosclerosis. STUDY DESIGN: We determined the effect of nicotine on the expression of adhesion molecules, intercellular adhesion molecule (ICAM-1), and vascular cell adhesion molecule (VCAM-1) in mouse cardiac vascular endothelial cells and the involvement of important known intermediaries, namely p38 mitogen-activated protein kinase (MAPK) signaling pathway. RESULTS: Our results indicate that nicotine can enhance the expression of ICAM-1 and VCAM-1 on mouse cardiac vascular endothelial cell via p38 MAPK signaling pathway, resulting in increased expression of the cellular adhesion molecules ICAM-1 and VCAM-1. CONCLUSION: We demonstrate that 10(-6) M nicotine maximally enhances mouse cardiac vascular endothelial cell expression of ICAM-1 and VCAM-1 at 8 hours. Our results provide a putative mechanism by which nicotine stimulates expression of these adhesion molecules via p38 MAPK signaling pathway.

Application of low dose of FK506 in pancreas transplantation model in Wistar-SD rats.

OBJECTIVE: To probe into application of low dose of FK506(Tacrolimus) in pancreas transplantation. METHODS: Effects of low-dose FK506 (Tacrolimus) in pancreas transplantation with examination of ELISA Electron microscopy and TUNEL by method of random control were studied. RESULTS: Blood glucose concentration in control group is higher than that in treated group A (FK506) and treated group B (CsA) 7 days after transplantation (p < 0.05). Serum C-peptide and insulin concentrations in control group are less than that in treated group A (FK506) and treated group B (CsA) 7 days after transplantation (p < 0.05). Blood glucose, serum C-peptide and insulin concentrations are same as that in control group, group A (FK506) and group B (CsA) (p > 0.05).There are more apoptotic nuclei in control group than that in treated group A (FK506) and treated group B (CsA) (p < 0.05). There is no significant difference between group A (FK506) and treated group B (CsA) in sum of apoptotic nuclei (p > 0.05). There is no significant difference among treated group A (FK506) and treated group B (CsA) in electron microscopy fields. CONCLUSION: Low-dose FK506 applied in pancreas transplantation could not only be effective for immunosuppressive, but also be safe for islet cells of pancreas.

Mechanisms of diabetes mellitus induced with FK506 in SD rats models.

BACKGROUND: Tacrolimus causes post-transplant diabetes mellitus, however the pathogenetic mechanisms remain controversial. In this study we probed into the mechanisms of tacrolimus-induced diabetes mellitus in rats. METHODS: Glucose levels were determined on whole blood samples using a glucose oxidase method. Levels of serum insulin and C-peptide were measured with ELISA. Histological damage of ultra-structure and apoptosis of beta cells of the pancreas were assayed with electric microscope and tunnel methods respectively.--Ultra-structure were assayed with electric microscope and apoptosis of beta cells of the pancreas were assayed with tunnel methods. Immunohistochemistry was utilized to detect the sum of insulin receptors of hepatic cells. RESULTS: Compared to control group, insulin and C peptide levels in serum decreased in rats of diabetes mellitus models induced with FK506(P<0.05). Compared to the control group, the sum of apoptosis body in pancreatic islets increased in rats of diabetes mellitus models induced with FK506 (P<0.05). Compared to the control group, electron microscopy showed cytoplasm swelling and vacuolization, and marked decrease or absence of dense-core secretory granules in beta cells in rats with diabetes mellitus induced with FK506.Compared to the control group, expression of insulin receptor of hepatic cell decreased in rats of diabetes mellitus models induced with FK506 (P<0.05). CONCLUSION: Pathogenetic mechanisms of rats of diabetes mellitus models induced with FK506 including reduction of secretion of insulin in beta cells of pancreatic islets, damages of ultra-structure of beta cells of pancreatic islets, increasing of apoptosis of beta cells of pancreatic islets and decreasing of expression of insulin receptors in hepatic cells.