Vasopressin attenuates ischemia-reperfusion injury via reduction of oxidative stress and inhibition of mitochondrial permeability transition pore opening in rat hearts

Meldonium, as a potential neuroprotective agent, promotes neuronal survival by protecting mitochondria in cerebral ischemia-reperfusion injury

BACKGROUND

Stroke is a globally dangerous disease capable of causing irreversible neuronal damage with limited therapeutic options. Meldonium, an inhibitor of carnitine-dependent metabolism, is considered an anti-ischemic drug. However, the mechanisms through which meldonium improves ischemic injury and its potential to protect neurons remain largely unknown.

METHODS

A rat model with middle cerebral artery occlusion (MCAO) was used to investigate meldonium's neuroprotective efficacy in vivo. Infarct volume, neurological deficit score, histopathology, neuronal apoptosis, motor function, morphological alteration and antioxidant capacity were explored via 2,3,5-Triphenyltetrazolium chloride staining, Longa scoring method, hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay, rotarod test, transmission electron microscopy and Oxidative stress index related kit. A primary rat hippocampal neuron model subjected to oxygen-glucose deprivation reperfusion was used to study meldonium's protective ability in vitro. Neuronal viability, mitochondrial membrane potential, mitochondrial morphology, respiratory function, ATP production, and its potential mechanism were assayed by MTT cell proliferation and cytotoxicity assay kit, cell-permeant MitoTracker® probes, mitochondrial stress, real-time ATP rate and western blotting.

RESULTS

Meldonium markedly reduced the infarct size, improved neurological function and motor ability, and inhibited neuronal apoptosis in vivo. Meldonium enhanced the morphology, antioxidant capacity, and ATP production of mitochondria and inhibited the opening of the mitochondrial permeability transition pore in the cerebral cortex and hippocampus during cerebral ischemia-reperfusion injury (CIRI) in rats. Additionally, meldonium improved the damaged fusion process and respiratory function of neuronal mitochondria in vitro. Further investigation revealed that meldonium activated the Akt/GSK-3β signaling pathway to inhibit mitochondria-dependent neuronal apoptosis.

CONCLUSION

Our study demonstrated that meldonium shows a neuroprotective function during CIRI by preserving the mitochondrial function, thus prevented neurons from apoptosis.

Cocaine and amphetamine-regulated transcript improves myocardial ischemia-reperfusion injury through PI3K/AKT signalling pathway

Myocardial ischemia-reperfusion injury (MIRI) is a common clinic scenario that occurs in the context of reperfusion therapy for acute myocardial infarction. It has been shown that cocaine and amphetamine-regulated transcript (CART) can ameliorate cerebral ischemia-reperfusion (I/R) injury, but the effect of CART on MIRI has not been studied yet. Here, we revealed that CART protected the heart during I/R process by inhibiting apoptosis and excessive autophagy, indicating that CART would be a potential drug candidate for the treatment of MIRI. Further analysis showed that CART upregulated the activation of phospho-AKT, leading to downregulation of lactate dehydrogenase (LDH) release, apoptosis, oxidative stress and excessive autophagy after I/R, which was inhibited by PI3K inhibitor, LY294002. Collectively, CART attenuated MIRI through inhibition of cardiomyocytes apoptosis and excessive autophagy, and the protective effect was dependent on PI3K/AKT signalling pathway.

Traditional uses, phytochemistry, pharmacology, toxicity and clinical application of traditional Chinese medicine Cynoglossum amabile: a review

Cynoglossum amabile, a member of the Boraginaceae family, is a well-known traditional Chinese medicine and ethnomedicine known as Daotihu. Despite several studies confirming the presence of bioactive pyrrolizidine alkaloids such as amabiline, ambelline, echinatine, europine, and others in C. amabile, there has been no comprehensive review of its traditional uses, phytochemistry, and pharmacology thus far. This review was conducted by thoroughly examining the literature and analyzing network databases. It covers various aspects of C. amabile, including botanical characteristics, geographical distribution, traditional applications, phytochemistry, pharmacological activities, toxicology, and clinical applications. The results have shown that C. amabile has been traditionally used for medicinal, edible, and ornamental purposes in China for many centuries. The whole plant, root, and leaf of C. amabile are used by different ethnic groups, such as Lisu, Bai, Naxi, Yi, Jinuo, and Han, to treat malaria, hepatitis, dysentery, leucorrhea, tuberculosis cough, fracture, joint dislocation, trauma bleeding, and skin carbuncle abscess. A total of 47 chemical components, including alkaloids (pyrrolizidine alkaloids, PAs), sterols, organic acids, and saccharides, were isolated from C. amabile. Pharmacological studies show that the chemical extracts of C. amabile possess various biological activities, such as anti-inflammatory, anti-tumor, anti-microbial, cardiovascular effects, ganglionic action, and acetylcholinesterase inhibition. However, it is important to note that C. amabile exhibits hepatotoxicity, with its toxicity being linked to its primary PAs components. Although preliminary studies suggest potential applications in the treatment of prostate diseases and alopecia, further research is needed to validate these clinical uses. Our review highlights the traditional uses, phytochemistry, biological activity, toxicity, and clinical applications of C. amabile. It emphasizes the essential guiding role of the indigenous medicinal knowledge system in developing new drugs. Previous studies have shown that the phytochemical and pharmacological characteristics of C. amabile are significantly related to its traditional medicinal practices. Cynoglossum amabile has excellent market potential and can be further analyzed in terms of phytochemistry, pharmacology, and toxicology, which are critical for its clinical drug safety, quality evaluation, and resource development.

Effect of Cold Adaptation on the State of Cardiovascular System and Cardiac Tolerance to Ischemia/Reperfusion Injury

Despite the unconditional success achieved in the treatment and prevention of AMI over the past 40 years, mortality in this disease remains high. Hence, it is necessary to develop novel drugs with mechanism of action different from those currently used in clinical practices. Studying the molecular mechanisms involved in the cardioprotective effect of adapting to cold could contribute to the development of drugs that increase cardiac tolerance to the impact of ischemia/reperfusion. An analysis of the published data shows that the long-term human stay in the Far North contributes to the occurrence of cardiovascular diseases. At the same time, chronic and continuous exposure to cold increases tolerance of the rat heart to ischemia/ reperfusion. It has been demonstrated that the cardioprotective effect of cold adaptation depends on the activation of ROS production, stimulation of the β2-adrenergic receptor and protein kinase C, MPT pore closing, and KATP channel.

Interplay of Angiotensin Peptides, Vasopressin, and Insulin in the Heart: Experimental and Clinical Evidence of Altered Interactions in Obesity and Diabetes Mellitus

The present review draws attention to the specific role of angiotensin peptides [angiotensin II (Ang II), angiotensin-(1-7) (Ang-(1-7)], vasopressin (AVP), and insulin in the regulation of the coronary blood flow and cardiac contractions. The interactions of angiotensin peptides, AVP, and insulin in the heart and in the brain are also discussed. The intracardiac production and the supply of angiotensin peptides and AVP from the systemic circulation enable their easy access to the coronary vessels and the cardiomyocytes. Coronary vessels and cardiomyocytes are furnished with AT1 receptors, AT2 receptors, Ang (1-7) receptors, vasopressin V1 receptors, and insulin receptor substrates. The presence of some of these molecules in the same cells creates good conditions for their interaction at the signaling level. The broad spectrum of actions allows for the engagement of angiotensin peptides, AVP, and insulin in the regulation of the most vital cardiac processes, including (1) cardiac tissue oxygenation, energy production, and metabolism; (2) the generation of the other cardiovascular compounds, such as nitric oxide, bradykinin (Bk), and endothelin; and (3) the regulation of cardiac work by the autonomic nervous system and the cardiovascular neurons of the brain. Multiple experimental studies and clinical observations show that the interactions of Ang II, Ang(1-7), AVP, and insulin in the heart and in the brain are markedly altered during heart failure, hypertension, obesity, and diabetes mellitus, especially when these diseases coexist. A survey of the literature presented in the review provides evidence for the belief that very individualized treatment, including interactions of angiotensins and vasopressin with insulin, should be applied in patients suffering from both the cardiovascular and metabolic diseases.

Activation of Autophagic Flux Maintains Mitochondrial Homeostasis during Cardiac Ischemia/Reperfusion Injury

Reperfusion injury after extended ischemia accounts for approximately 50% of myocardial infarct size, and there is no standard therapy. HDAC inhibition reduces infarct size and enhances cardiomyocyte autophagy and PGC1α-mediated mitochondrial biogenesis when administered at the time of reperfusion. Furthermore, a specific autophagy-inducing peptide, Tat-Beclin 1 (TB), reduces infarct size when administered at the time of reperfusion. However, since SAHA affects multiple pathways in addition to inducing autophagy, whether autophagic flux induced by TB maintains mitochondrial homeostasis during ischemia/reperfusion (I/R) injury is unknown. We tested whether the augmentation of autophagic flux by TB has cardioprotection by preserving mitochondrial homeostasis both in vitro and in vivo. Wild-type mice were randomized into two groups: Tat-Scrambled (TS) peptide as the control and TB as the experimental group. Mice were subjected to I/R surgery (45 min coronary ligation, 24 h reperfusion). Autophagic flux, mitochondrial DNA (mtDNA), mitochondrial morphology, and mitochondrial dynamic genes were assayed. Cultured neonatal rat ventricular myocytes (NRVMs) were treated with a simulated I/R injury to verify cardiomyocyte specificity. The essential autophagy gene, ATG7, conditional cardiomyocyte-specific knockout (ATG7 cKO) mice, and isolated adult mouse ventricular myocytes (AMVMs) were used to evaluate the dependency of autophagy in adult cardiomyocytes. In NRVMs subjected to I/R, TB increased autophagic flux, mtDNA content, mitochondrial function, reduced reactive oxygen species (ROS), and mtDNA damage. Similarly, in the infarct border zone of the mouse heart, TB induced autophagy, increased mitochondrial size and mtDNA content, and promoted the expression of PGC1α and mitochondrial dynamic genes. Conversely, loss of ATG7 in AMVMs and in the myocardium of ATG7 cKO mice abolished the beneficial effects of TB on mitochondrial homeostasis. Thus, autophagic flux is a sufficient and essential process to mitigate myocardial reperfusion injury by maintaining mitochondrial homeostasis and partly by inducing PGC1α-mediated mitochondrial biogenesis.

The role of vasopressin V1A and oxytocin OTR receptors in protective effects of arginine vasopressin against H2O2-induced oxidative stress in H9C2 cells

BACKGROUND

Oxidative stress, has been shown to play an important role in the pathophysiology of cardiac remodelling and heart failure. The aim of study is effect of arginine vasopressin (AVP) on apoptosis of cardiomyocyte via its receptors.

MATERIALS AND METHODS

The cell viability effect of AVP in H9C2 cardiomyocytes was assayed using the MTT method. The transcription and translation level of apoptosis genes (Bax, Bcl-2, caspase-3) were discovered with qRT-PCR and western blotting.

RESULTS

The results showed that vasopressin could reduce apoptosis in cardiomyocytes cell line through downregulation of caspase-3, BAX and upregulation of Bcl-2 (p < .001). Also, there was a decrease in anti-apoptosis effect of vasopressin when V1A and OTR receptors were blocked with their antagonists.

DISCUSSION

These results suggest that activation of V1A and OTR receptors in H9C2 cells mediate protective effect of vasopressin via regulating apoptosis marker that lead to cell survival under conditions of stress oxidative.Key pointAVP may contribute to the improvement of heart ischaemia through its actions on V1A and OTR receptors.

Honokiol Provides Cardioprotection from Myocardial Ischemia/Reperfusion Injury (MI/RI) by Inhibiting Mitochondrial Apoptosis via the PI3K/AKT Signaling Pathway

Background

Myocardial injury refers to a major complication that occurs in myocardial ischemia/reperfusion injury (MI/RI). Honokiol is a well-recognized active compound extracted from the traditional Chinese herb known as Magnolia officinalis and is utilized in treating different vascular diseases. This research is aimed at examining whether Honokiol might alleviate myocardial injury in an MI/RI model.

Methods

Seventy-eight male C57BL/6 mice were categorized randomly into three cohorts including the Sham operation (Sham) cohort, the MI/RI cohort (Con), and the Honokiol cohort (n = 26 for each cohort). The mice in the Honokiol cohort were treated with Honokiol before MI/RI surgery (0.2 mg/kg/day for 14 days, intraperitoneal), while the mice in the Con cohort were given an intraperitoneal injection with an equivalent volume of vehicle (DMSO) daily in 14 days prior to exposure to MI/RI. After the surgery, creatine kinase- (CK-) MB and cardiac troponin T (cTnT) levels, as well as the infarct area, were measured to assess the degree of myocardial damage. Apoptotic levels were detected using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. Electron microscopy was utilized to identify mitochondrial damage. Lastly, the expression levels of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), cleaved caspase-9, cytochrome C (Cyt-C), B cell lymphoma/leukemia-2 (Bcl-2), B cell lymphoma/leukemia-2 associated X (Bax), AKT, p-AKT, PI3K, and p-PI3K were analyzed utilizing western blotting.

Results

Honokiol can reduce the MI/RI-induced cTnT and CK-MB levels, apoptosis index, and mitochondrial swelling in cardiomyocytes via activating the PI3K/AKT signaling pathway.

Conclusion

Honokiol provides cardiac protection from MI/RI by suppressing mitochondrial apoptosis through the PI3K/AKT signaling pathway.

Clozapine attenuates mitochondrial dysfunction, inflammatory gene expression, and behavioral abnormalities in an animal model of schizophrenia

Beyond abnormalities in the neurotransmitter hypothesis, recent evidence suggests that mitochondrial dysfunction and immune-inflammatory responses contribute to the pathophysiology of schizophrenia. The prefrontal cortex (PFC) undergoes maturation and development during adolescence, which is a critical time window in life that is vulnerable to environmental adversities and the development of psychiatric disorders such as schizophrenia. Applying eight weeks of post-weaning social isolation stress (PWSI) to rats, as an animal model of schizophrenia, we decided to investigate the effects of PWSI on the mitochondrial function and expression of immune-inflammatory genes in the PFC of normal and stressed rats. To do this, control and PWSI rats were divided into treatment (clozapine; CLZ, 2.5 mg/kg/day for 28 days) and non-treatment sub-groups. Our results showed PWSI caused schizophrenic-like behaviors in rats and induced mitochondrial dysfunction as well as upregulation of genes associated with innate immunity in the PFC. Chronic treatment with CLZ attenuated the effects of PWSI on behavioral abnormalities, mitochondrial dysfunction, and immune-inflammatory responses in the PFC of rats. These results may advance our understanding about the mechanism of action of CLZ that targets mitochondrial dysfunction and immune-inflammatory responses as factors involved in the pathophysiology of schizophrenia.

Oxytocin Receptor Signaling in Vascular Function and Stroke

The oxytocin receptor (OXTR) is a G protein-coupled receptor with a diverse repertoire of intracellular signaling pathways, which are activated in response to binding oxytocin (OXT) and a similar nonapeptide, vasopressin. This review summarizes the cell and molecular biology of the OXTR and its downstream signaling cascades, particularly focusing on the vasoactive functions of OXTR signaling in humans and animal models, as well as the clinical applications of OXTR targeting cerebrovascular accidents.

Curculigoside attenuates myocardial ischemia‑reperfusion injury by inhibiting the opening of the mitochondrial permeability transition pore

The aim of the present study was to determine whether curculigoside protects against myocardial ischemia-reperfusion injury (MIRI) and to investigate the underlying mechanisms. An in vitro model of hypoxia/reoxygenation (H/R) was established by culturing H9c2 cells under hypoxic conditions for 12 h, followed by reoxygenation for 1 h. Cell Counting kit-8 and lactate dehydrogenase (LDH) assays were subsequently used to examine cell viability and the degree of cell injury. In addition, isolated rat hearts were subjected to 30 min of ischemia followed by 1 h of reperfusion to establish a MIRI model. Triphenyltetrazolium chloride (TTC) staining was performed to measure the infarct size. Furthermore, TUNEL staining and flow cytometry were employed to evaluate cell apoptosis. The opening of the mitochondrial permeability transition pore (MPTP) and changes in the mitochondrial membrane potential (ΔΨm) were assessed. Reverse transcription-quantitative PCR and western blot analysis were performed to investigate the expression levels of mitochondrial apoptosis-related proteins. Curculigoside pre-treatment significantly improved cell viability, decreased cell apoptosis and LDH activity, and reduced the infarct size and myocardial apoptosis in vitro and ex vivo, respectively. Moreover, curculigoside markedly inhibited MPTP opening and preserved the ΔΨm. In addition, curculigoside significantly decreased the expression of cytochrome c, apoptotic protease activating factor-1, cleaved caspase-9 and cleaved caspase-3. Notably, atractyloside, a known MPTP opener, abrogated the protective effects of curculigoside. On the whole, the present study demonstrated that curculigoside protected against MIRI, potentially by decreasing the levels of mitochondria-mediated apoptosis via the inhibition of MPTP opening. Therefore, the results obtained in the present study may provide the theoretical basis for the future clinical application of curculigoside.

The role of DNA damage as a therapeutic target in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic kidney disease and is caused by heterozygous germ-line mutations in either PKD1 (85%) or PKD2 (15%). It is characterised by the formation of numerous fluid-filled renal cysts and leads to adult-onset kidney failure in ~50% of patients by 60 years. Kidney cysts in ADPKD are focal and sporadic, arising from the clonal proliferation of collecting-duct principal cells, but in only 1-2% of nephrons for reasons that are not clear. Previous studies have demonstrated that further postnatal reductions in PKD1 (or PKD2) dose are required for kidney cyst formation, but the exact triggering factors are not clear. A growing body of evidence suggests that DNA damage, and activation of the DNA damage response pathway, are altered in ciliopathies. The aims of this review are to: (i) analyse the evidence linking DNA damage and renal cyst formation in ADPKD; (ii) evaluate the advantages and disadvantages of biomarkers to assess DNA damage in ADPKD and finally, (iii) evaluate the potential effects of current clinical treatments on modifying DNA damage in ADPKD. These studies will address the significance of DNA damage and may lead to a new therapeutic approach in ADPKD.

Myocardial Adaptation in Pseudohypoxia: Signaling and Regulation of mPTP via Mitochondrial Connexin 43 and Cardiolipin

Therapies intended to mitigate cardiovascular complications cannot be applied in practice without detailed knowledge of molecular mechanisms. Mitochondria, as the end-effector of cardioprotection, represent one of the possible therapeutic approaches. The present review provides an overview of factors affecting the regulation processes of mitochondria at the level of mitochondrial permeability transition pores (mPTP) resulting in comprehensive myocardial protection. The regulation of mPTP seems to be an important part of the mechanisms for maintaining the energy equilibrium of the heart under pathological conditions. Mitochondrial connexin 43 is involved in the regulation process by inhibition of mPTP opening. These individual cardioprotective mechanisms can be interconnected in the process of mitochondrial oxidative phosphorylation resulting in the maintenance of adenosine triphosphate (ATP) production. In this context, the degree of mitochondrial membrane fluidity appears to be a key factor in the preservation of ATP synthase rotation required for ATP formation. Moreover, changes in the composition of the cardiolipin’s structure in the mitochondrial membrane can significantly affect the energy system under unfavorable conditions. This review aims to elucidate functional and structural changes of cardiac mitochondria subjected to preconditioning, with an emphasis on signaling pathways leading to mitochondrial energy maintenance during partial oxygen deprivation.

Coping facilitated troponin T increases and hypo-responsivity in the copeptin-HPA-axis during acute mental stress in a black cohort: The SABPA study

BACKGROUND

Defensive coping (DefS) was associated with a vulnerable cardiovascular profile in blacks. The copeptin/vasopressin system is a manifestation of hypothalamic-pituitary-adrenal-axis activity and may act as an acute compensatory mechanism when there is a disruption in volume-loading homeostasis, i.e. when cardiac stress is evident. Whether DefS will influence associations between copeptin and cardiac stress markers, remains unclear. Here we aimed to determine associations between acute mental stress responses of copeptin, vascular responsiveness and biomarkers of cardiomyocyte injury [cardiac troponin T (cTnT)] and cardiac wall-stress [N-terminal pro-brain natriuretic peptide (NT-proBNP)] in DefS race groups.

METHODS

South African black and white teachers (n = 378) of both sexes, participated in this target population study. Cases with a history of myocardial infarction, stroke and atrial fibrillation were excluded. We obtained coping scores (Coping Strategy Indicator), beat-to-beat blood pressure and fasting blood samples at rest and after 1-min exposure to the Stroop-Colour-Word-Conflict-test.

RESULTS

Interaction effects (p < .05) for copeptin percentage change (%) during the Stroop-Colour-Word-Conflict-test determined stratification of participants into race and DefS (≥26, above-median score) groups. In DefS blacks, Stroop-Colour-Word-Conflict-test exposure elicited increases in cTnT%, NT-proBNP% and diastolic-blood pressure%. Again, in these individuals, multiple regression analyses showed positive associations between copeptin% and total peripheral resistance%; with inverse associations between copeptin% and cTnT% (p < .05). None of these associations were found in DefS whites.

CONCLUSIONS

Utilisation of DefS in blacks provoked vascular hyper-responsiveness and cardiac wall stress (elevated cTnT and NT-proBNP); possibly mediated via the copeptin/vasopressin system. However, a presumably hypo-responsive hypothalamic-pituitary-adrenal-axis during stress exposure could not counteract coronary perfusion deficits via additional copeptin/vasopressin release. The presence of defensiveness may have clinical implications in preventive cardiology.

Neuroendocrine drivers of risk and resilience: The influence of metabolism & mitochondria

The manifestation of risk versus resilience has been considered from varying perspectives including genetics, epigenetics, early life experiences, and type and intensity of the challenge with which the organism is faced. Although all of these factors are central to determining risk and resilience, the current review focuses on what may be a final common pathway: metabolism. When an organism is faced with a perturbation to the environment, whether internal or external, appropriate energy allocation is essential to resolving the divergence from equilibrium. This review examines the potential role of metabolism in the manifestation of stress-induced neural compromise. In addition, this review details the current state of knowledge on neuroendocrine factors which are poised to set the tone of the metabolic response to a systemic challenge. The goal is to provide an essential framework for understanding stress in a metabolic context and appreciation for key neuroendocrine signals.

Hyper-methylation of AVPR1A and PKCΒ gene associated with insensitivity to arginine vasopressin in human pre-eclamptic placental vasculature

Background

Pre-eclampsia is a leading cause of maternal mortality and morbidity. Although the exact mechanisms that cause pre-eclampsia remain unclear, it is undeniable that abnormal placental function and circulation are a center for initiation pre-eclampsia. As a potent vasoconstrictor, arginine vasopressin (AVP) has long been implicated in controlling placental vascular tone and circulation; its secretion is grossly elevated in pre-eclamptic circulation. However, little is known about the reactivity of AVP in pre-eclamptic placental vasculature.

Methods

To reveal the special features of placental vascular regulations with placental pathophysiological changes, as well as the corresponding molecular mechanisms under pre-eclamptic conditions, vascular function and molecular assays were conducted with placental vessel samples from normal and pre-eclamptic pregnancies.

Findings

The present study found that vasoconstriction responses of placental vessels to AVP were attenuated in pre-eclampsia as compared to in normal pregnancy. The insensitivity of AVP was correlated with the down-regulated AVP receptor 1a (AVPR1A, AVPR1A gene) and protein kinase C isoform β (PKCβ, PKCΒ gene), particularly the hyper-methylation-mediated AVPR1A and PKCΒ gene down-regulation, respectively.

Interpretation

The findings collectively revealed that aberrant DNA methylation-mediated gene expressions are correlated with vascular dysfunction in pre-eclamptic placental circulation.

Fund

This work was supported by National Nature & Science Foundation of China. “333 Project”, “Six one project”, “Shuang Chuang Tuan Dui” and Key Discipline “Fetal medicine” of Jiangsu Province, and the Suzhou city “Wei Sheng Ren Cai” program.

Ca2+/Calmodulin-Dependent Protein Kinase II Regulation by Inhibitor 1 of Protein Phosphatase 1 Protects Against Myocardial Ischemia-Reperfusion Injury

Ca²⁺/calmodulin-dependent protein kinase IIδ (CaMKIIδ) plays a vital role in cardiovascular system. However, the potential protective role of inhibitor 1 of protein phosphatase 1 (I1PP1), which can regulate CaMKII, on myocardial ischemia-reperfusion (I/R) injury remains unknown. In the present study, expression of CaMKIIδ variants was detected by quantitative real-time polymerase chain reaction. I1PP1 was overexpressed by pericardial injection of recombinant adenovirus. Two weeks later, rats were subjected to left anterior descending ligation for 30 minutes followed by reperfusion. Myocardial infarct size was assessed by Evans blue/triphenyl tetrazolium chloride staining. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activity as well as myocardial pathological structure were detected. CaMKII activity was evaluated by phosphorylation of phospholamban (PLB) and oxidation of CaMKII. Expression of dynamin-related protein 1 (DRP1) and optic atrophy 1 (OPA1) in the mitochondria was measured by Western blot. We found that CaMKIIδA and CaMKIIδB expression decreased, while the expression of CaMKIIδC increased after myocardial I/R. Moreover, after 30-minute ischemia followed by 6 hours of reperfusion, I1PP1 overexpression reduced myocardial infarct size, decreased serum CK and LDH activity, ameliorated myocardial pathological structure, inhibited PLB phosphorylation at Thr17, suppressed CaMKII oxidation, elevated CaMKIIδA and CaMKIIδB variants but reduced CaMKIIδC variants, attenuated myocardial oxidative stress, improved myocardial mitochondrial ultrastructure, increased mitochondrial number and mitochondrial DNA copy number, and decreased DRP1 but increased OPA1 protein expression from the mitochondria in rats. Thus, I1PP1 regulated CaMKII, protected mitochondrial function, reduced oxidative stress, and attenuated myocardial I/R injury.

HDAC inhibition induces autophagy and mitochondrial biogenesis to maintain mitochondrial homeostasis during cardiac ischemia/reperfusion injury

AIMS

The FDA-approved histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA, Vorinostat) has been shown to induce cardiomyocyte autophagy and blunt ischemia/reperfusion (I/R) injury when administered at the time of reperfusion. However, the precise mechanisms underlying the cardioprotective activity of SAHA are unknown. Mitochondrial dysfunction and oxidative damage are major contributors to myocardial apoptosis during I/R injury. We hypothesize that SAHA protects the myocardium by maintaining mitochondrial homeostasis and reducing reactive oxygen species (ROS) production during I/R injury.

METHODS

Mouse and cultured cardiomyocytes (neonatal rat ventricular myocytes and human embryonic stem cell-derived cardiomyocytes) I/R models were used to investigate the effects of SAHA on mitochondria. ATG7 knockout mice, ATG7 knockdown by siRNA and PGC-1α knockdown by adenovirus in cardiomyocytes were used to test the dependency of autophagy and PGC-1α-mediated mitochondrial biogenesis respectively.

RESULTS

Intact and total mitochondrial DNA (mtDNA) content and mitochondrial mass were significantly increased in cardiomyocytes by SAHA pretreatment before simulated I/R. In vivo, I/R induced >50% loss of mtDNA content in the border zones of mouse hearts, but SAHA pretreatment and reperfusion treatment alone reverted mtDNA content and mitochondrial mass to control levels. Moreover, pretreatment of cardiomyocytes with SAHA resulted in a 4-fold decrease in I/R-induced loss of mitochondrial membrane potential and a 25%-40% reduction in cytosolic ROS levels. However, loss-of-function of ATG7 in cardiomyocytes or mouse myocardium abolished the protective effects of SAHA on ROS levels, mitochondrial membrane potential, mtDNA levels, and mitochondrial mass. Lastly, PGC-1α gene expression was induced by SAHA in NRVMs and mouse heart subjected to I/R, and loss of PGC-1α abrogated SAHA's mitochondrial protective effects in cardiomyocytes.

CONCLUSIONS

SAHA prevents I/R induced-mitochondrial dysfunction and loss, and reduces myocardial ROS production when given before or after the ischemia. The protective effects of SAHA on mitochondria are dependent on autophagy and PGC-1α-mediated mitochondrial biogenesis.

High doses of sodium tungstate can promote mitochondrial dysfunction and oxidative stress in isolated mitochondria

Tungstate (W) is recognized as an agent of environmental pollution and a substitute to depleted uranium. According to some preliminary studies, tungstate toxicity is related to the formation of reactive oxygen species (ROS) under abnormal pathological conditions. The kidneys and liver are the main tungstate accumulation sites and important targets of tungstate toxicity. Since the mitochondrion is the main ROS production site, we evaluated the mechanistic toxicity of tungstate in isolated mitochondria for the first time, following a two-step ultracentrifugation method. Our findings demonstrated that tungstate-induced mitochondrial dysfunction is related to the increased formation of ROS, lipid peroxidation, and potential membrane collapse, correlated with the amelioration of adenosine triphosphate and glutathione contents. The present study indicated that mitochondrial dysfunction was associated with disruptive effects on the mitochondrial respiratory chain and opening of mitochondrial permeability transition (MPT) pores, which is correlated with cytochrome c release. Our findings suggest that high concentrations of tungstate (2 mM)-favored MPT pore opening in the inner membranes of liver and kidney mitochondria of rats. Besides, the results indicated higher tungstate susceptibility in the kidneys, compared with the liver.

Protective effect of morin on myocardial ischemia‑reperfusion injury in rats

Morin, a natural flavonol, exhibits antioxidative, anti-inflammatory and anti-apoptotic effects in various pathological and physiological processes. However, whether morin exerts a protective effect on myocardial ischemia-reperfusion injury (MIRI) is unknown. The present study aimed to determine the effect of morin on MIRI in cultured cardiomyocytes and isolated rat hearts, and to additionally explore the underlying mechanism. The effect of morin on the viability, lactate dehydrogenase (LDH) activity and apoptosis of H9c2 cardiomyocytes subjected to hypoxia/reoxygenation, and cardiac function and infarct size of rat hearts following ischemia/reperfusion in an animal model were measured. Furthermore, the mitochondrial permeability transition pore (MPTP) opening, mitochondrial membrane potential (ΔΨm), and the change in the expression levels of B-cell lymphoma 2 (Bcl2)-associated X protein (Bax), Bcl-2 and mitochondrial apoptosis-associated proteins following MPTP opening were also detected. The results indicated that morin treatment significantly increased cell viability, decreased LDH activity and cell apoptosis, improved the recovery of cardiac function and decreased the myocardial infarct size. Furthermore, morin treatment markedly inhibited MPTP opening, prevented the decrease of ΔΨm, and decreased the expression of cytochrome c, apoptotic protease activating factor-1, caspase-9, caspase-3 and the Bax/Bcl-2 ratio. However, these beneficial effects were reversed by treatment with atractyloside, an MPTP opener. The present study demonstrated that morin may prevent MIRI by inhibiting MPTP opening and revealed the possible mechanism of the cardioprotection of morin and its acting target. It also provided an important theoretical basis for the research on drug interventions for MIRI in clinical applications.

Protective effects of Ziziphora tenuior extract against chlorpyrifos induced liver and lung toxicity in rat: Mechanistic approaches in subchronic study

Chlorpyrifos (CPF) is one of the most widely used organophosphorus, which has spurred renewed interest. This study was conducted to investigate the protective effect of ziziphora tenuior extract against CPF-induced liver and lung toxicity. This study conducted 8-week rat sub-chronic toxicity study and then the effect of ziziphora tenuior extract in 3 different doses (40, 80, 160 mg/kg) was determined. We administrated maximum tolerated dose of CPF (6.75 mg/kg) by gavage for 8 weeks (5 times in week) to male rats. Rats were sacrificed 24 h after last dose and the biochemical analysis, which confirms involvement of oxidative stress in the pathogenesis of CPF toxicity in liver including increased in lipid peroxidation, protein carbonyl content, and ROS formation, glutathione depletion, decreased of antioxidant effect via frap oxidation and cytochrome c expulsion. In addition, pathological lesions confirm the dysfunction of the organs (liver and lung). In addition, using of ziziphora extract as an antioxidant is resulted in amelioration of oxidative stress marker in liver and lung damage. In conclusion, the current study revealed that CPF toxicity is related to oxidative stress and induction of cell death signaling and cotreatment with ziziphora extract is recommended in the routine therapy for the protection against CPF induced liver and lung tissue damage.

Terlipressin protects intestinal epithelial cells against oxygen-glucose deprivation/re-oxygenation injury via the phosphatidylinositol 3-kinase pathway

Intestinal ischemia/reperfusion (I/R) injury is associated with a high morbidity and mortality. Vasopressin is administered to critically ill patients with potential intestinal I/R. However, the impacts of vasopressin on intestinal epithelia under ischemic/anoxic conditions remain unclear. The aim of the present study was to evaluate the effects of terlipressin, a highly selective vasopressin V1 receptor agonist, on oxygen and glucose deprivation/re-oxygenation (OGD/R)-induced damage in intestinal epithelial cells (IEC-6). IEC-6 cells were subjected to OGD for 4 h, followed by 4 h re-oxygenation. Terlipressin was incubated with cells for 4 h following OGD. Following OGD/R, IEC-6 cell viability, proliferation and apoptosis, as well as cell cycle dynamics, were assessed and the levels of tumor necrosis factor (TNF)-α and 15-F2t-isoprostane in the culture medium were measured. In addition, wortmannin, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, was administrated to investigate the mechanism of terlipressin action. The results demonstrated that IEC-6 cell viability and proliferation decreased, and cell apoptosis increased, following OGD/R. However, IEC-6 cell cycle dynamics did not significantly change 4 h after OGD. Incubation with 25 nM terlipressin significantly improved cell viability, proliferation and apoptosis. Furthermore, terlipressin inhibited the secretion of TNF-α and 15-F2t-isoprostane from IEC-6 cells following OGD/R. The aforementioned effects of terlipressin were completely abolished following the application of 2 µM wortmannin. Therefore, the current study demonstrated that terlipressin administration following OGD attenuates OGD/R-induced cell damage via the PI3K signaling pathway. These results may help physicians to better understand and more effectively use terlipressin in a clinical setting.

Protective roles of bioactive peptides during ischemia-reperfusion injury: From bench to bedside

Ischemia-reperfusion (I/R) is a well-known pathological condition which may lead to disability and mortality. I/R injury remains an unresolved and complicated situation in a number of clinical conditions, such as cardiac arrest with successful reanimation, as well as ischemic events in brain and heart. Peptides have many attractive advantages which make them suitable candidate drugs in treating I/R injury, such as low toxicity and immunogenicity, good solubility property, distinct tissue distribution pattern, and favorable pharmacokinetic profile. An increasing number of studies indicate that peptides could protect against I/R injury in many different organs and tissues. Peptides also face several therapeutic challenges that limit their clinical application. In this review, we present the mechanisms of action of peptides in reducing I/R injury, as well as further discuss modification strategies to improve the functional properties of bioactive peptides.

Extracellular Cl--free-induced cardioprotection against hypoxia/reoxygenation is associated with attenuation of mitochondrial permeability transition pore

The isotonic substitution of extracellular chloride by gluconate (extracellular Cl^--free) has been demonstrated to elicit cardioprotection by attenuating ischaemia/reperfusion-induced elevation of intracellular chloride ion concentration ([Cl^-]_i). However, the downstream mechanism underlying the cardioprotective effect of extracellular Cl^--free is not fully established. Here, it was investigated whether extracellular Cl^--free attenuates mitochondrial dysfunction after hypoxia/reoxygenation (H/R) and whether mitochondrial permeability transition pore (mPTP) plays a key role in the extracellular Cl^--free cardioprotection. H9c2 cells were incubated with or without Cl^--free solution, in which Cl^- was replaced with equimolar gluconate, during H/R. The involvement of mPTP was determined with atractyloside (Atr), a specific mPTP opener. The results showed that extracellular Cl^--free attenuated H/R-induced the elevation of [Cl^-]_i, accompanied by increase of cell viability and reduction of lactate dehydrogenase release. Moreover, extracellular Cl^--free inhibited mPTP opening, and improved mitochondria function, as indicated by preserved mitochondrial membrane potential and respiratory chain complex activities, decreased mitochondrial reactive oxygen species generation, and increased ATP content. Intriguingly, pharmacologically opening of the mPTP with Atr attenuated all the protective effects caused by extracellular Cl^--free, including suppression of mPTP opening, maintenance of mitochondrial membrane potential, and subsequent improvement of mitochondrial function. These results indicated that extracellular Cl^--free protects mitochondria from H/R injury in H9c2 cells and inhibition of mPTP opening is a crucial step in mediating the cardioprotection of extracellular Cl^--free.

New mechanistic approach of inorganic palladium toxicity: impairment in mitochondrial electron transfer

Human activities have increased the levels of palladium (Pd) that are progressively accumulating in the environment. The growing evidence of Pd toxicity has become the focus of serious concern for the environment, organisms and humans, with little data on the mechanism of Pd toxicity. Recent studies have suggested that mitochondria have a key role in Pd toxicity via mitochondrial membrane potential collapse and depletion of the cellular glutathione (GSH) level. Therefore, it was decided to determine the mechanistic toxicity of Pd towards isolated mitochondria via new and reliable methods. Isolated liver and kidney mitochondria were obtained by differential ultracentrifugation and incubated with different concentrations of Pd (100-400 μM). Our results showed that Pd induced mitochondrial dysfunction via an increase in mitochondrial ROS production and membrane potential collapse, which correlated to cytochrome c release. Also, increased disturbance in oxidative phosphorylation was also shown by the increase in ADP/ATP ratio in Pd-treated mitochondria, which indicates mitochondrial dysfunction in isolated liver and kidney mitochondria. Our results suggest that Pd-induced toxicity is the result of a disruptive effect on the mitochondrial respiratory chain, increasing the chance of cell death signaling. In addition, it is supposed that kidney tissue is more susceptible to Pd exposure than liver tissue.

Sasanquasaponin-induced cardioprotection involves inhibition of mPTP opening via attenuating intracellular chloride accumulation

Sasanquasaponin (SQS) has been reported to elicit cardioprotection by suppressing hypoxia/reoxygenation (H/R)-induced elevation of intracellular chloride ion concentration ([Cl^-]_i). Given that the increased [Cl^-]_i is involved to modulate the mitochondrial permeability transition pore (mPTP), we herein sought to further investigate the role of mPTP in the cardioprotective effect of SQS on H/R injury. H9c2 cells were incubated for 24h with or without 10μM SQS followed by H/R. The involvement of mPTP was determined with a specific mPTP agonist atractyloside (ATR). The results showed that SQS attenuated H/R-induced the elevation of [Cl^-]_i, accompanied by reduction of lactate dehydrogenase release and increase of cell viability. Moreover, SQS suppressed mPTP opening, and protected mitochondria, as indicated by preserved mitochondrial membrane potential and respiratory chain complex activities, decreased mitochondrial reactive oxygen species generation, and increased ATP content. Interestingly, extracellular Cl^--free condition created by replacing Cl^- with equimolar gluconate resulted in a decrease in [Cl^-]_i and induced protective effects similar to SQS preconditioning, whereas pharmacologically opening of the mPTP with ATR abolished all the protective effects induced by SQS or Cl^--free, including suppression of mPTP opening, maintenance of mitochondrial membrane potential, and subsequent improvement of mitochondrial function. The above results allow us to conclude that SQS-induced cardioprotection may be mediated by preserving the mitochondrial function through preventing mPTP opening via inhibition of H/R-induced elevation of [Cl^-]_i.

Changes in the metabolic profile and body weight of pre-pubertal gilts during prolonged monotonic exposure to low doses of zearalenone and deoxynivalenol

The aim of this study was to determine whether exposure to low doses of ZEN + DON induces changes in serum biochemical and hematological parameters in pre-pubertal gilts. In the evaluated groups, minor but statistically significant changes were noted in selected serum biochemical parameters, including glucose, total cholesterol, ALT, AST, AP, total bilirubin, P_in, Fe, K and Cl, and in hematological parameters, including WBC, eosinophils, basophils, monocytes, Ht, Hb, MCHC, HDW and PLT. A statistical analysis of the results revealed significant differences between groups in the values of WBC, eosinophils, basophils, Hb, Ht, PLT, glucose, ALT, AP, total bilirubin, Fe and K. Change trends were noted mainly in weeks II and V-VI. An analysis of the metabolic profile of pre-pubertal gilts exposed to ZEN + DON indicates that homeostasis and biotransformation of ZEN + DON can be toned down at the expense of the animals' energy reserves. Body weight gains were lower in group E, and BW gains were not observed in weeks II and VI. The activity levels of gilts decreased in the first weeks of exposure (I and II), but the drop was minimized by a compensatory effect, or in the last two weeks of exposure due to nutrient deficiency or insufficient supply of protein and energy with feed and feed additives, which decreased BW gains. Low doses of mycotoxins induce completely different changes in the metabolic test than higher doses. The above can probably be attributed to: (i) a negative compensatory effect, (ii) initiation of adaptive mechanisms and stimulation of the immune system, probably due to the allergizing properties of mycotoxins, (iii) excessive loss of energy and protein due to more effective feed utilization, or (iv) involvement in detoxification processes which leads to fatigue. Depending on the body's energy stores, the above processes tend to tone down the biotransformation of low doses of the examined mycotoxins but in the present study, the BW of gilts did not increase under exposure to a combination of ZEN + DON.

Morphine Attenuated the Cytotoxicity Induced by Arsenic Trioxide in H9c2 Cardiomyocytes

Arsenic trioxide (ATO) is an efficient drug for the treatment of the patients with acute promyelocytic leukemia (APL). Inhibition of proliferation as well as apoptosis, attenuation of migration, and induction of differentiation in tumor cells are the main mechanisms through which ATO acts against APL. Despite advantages of ATO in treatment of some malignancies, certain harmful side effects, such as cardiotoxicity, have been reported. It has been well documented that morphine has antioxidant, anti-apoptotic, and cytoprotective properties and is able to attenuate cytotoxicity. Therefore, in this study, we aimed to investigate the protective effects of morphine against ATO toxicity in H9c2 myocytes using multi-parametric assay including thiazolyl blue tetrazolium bromide (MTT) assay, reactive oxygen species (ROS) generation, caspase 3 activity, nuclear factor kappa B (NF-κB) phosphorylation assay, and expression of apoptotic markers. Our results showed that morphine (1 μM) attenuated cytotoxicity induced by ATO in H9c2 cells. Results of this study suggest that morphine may have protective properties in management of cardiac toxicity in patients who receive ATO as an anti-cancer treatment.

Cardioprotection provided by Echinatin against ischemia/reperfusion in isolated rat hearts

Background

This study evaluated the protective effect of Echinatin against myocardial ischemia/reperfusion (I/R) injury in rats.

Methods

The effect of Echinatin on cardiac function in rats subjected to I/R was demonstrated through improved Langendorff retrograde perfusion technology. Adult Sprague–Dawley rats were randomly divided into five groups, and myocardial infarct size was macroscopically estimated through 2,3,5-triphenyltetrazolium chloride staining. The coronary effluent was analyzed for the release of lactate dehydrogenase (LDH) and creatine kinase (CK) to assess the degree of cardiac injury. The concentrations of malondialdehyde (MDA), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were determined along with superoxide dismutase (SOD) activity using ELISA. Finally, cardiomyocyte apoptosis analysis was conducted with POD, an in situ cell death detection kit.

Results

Echinatin (0.5 and 2.5 μg/mL) pretreatment enhanced the maximum up/down rate of the left ventricular pressure (±dp/dtmax), improved the heart rate, increased the left ventricular developed pressure (LVDP), enhanced the coronary flow, and reduced the CK and LDH levels in the coronary flow of the treated group compared with the I/R group. Echinatin limited the contents of CK and LDH, improved the LVDP, reduced the contents of MDA, IL-6, and TNF-α, and increased the SOD activity. The infarct size and cell apoptosis in the hearts of the rats in the Echinatin-treated group were smaller and lower, respectively, than those in the hearts of the rats in the I/R control group.

Conclusion

Echinatin exerts a protective effect against I/R-induced myocardial injury on hearts. This effect may be attributed to the antioxidant and anti-inflammatory activities of this compound.

Less increase of copeptin and MR-proADM due to intervention with selenium and coenzyme Q10 combined: Results from a 4-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens

Intervention with selenium and coenzyme Q10 have recently been found to reduce mortality and increase cardiac function. The mechanisms behind these effects are unclear. As selenium and coenzyme Q10 is involved in the anti-oxidative defence, the present study aimed to evaluate effects of selenium and coenzyme Q10 on copeptin and adrenomedullin as oxidative stress biomarkers. Therefore 437 elderly individuals were included and given intervention for 4 years. Clinical examination and blood samples were undertaken at start and after 18 and 48 months. Evaluations of copeptin and MR-proADM changes were performed using repeated measures of variance. Cardiovascular mortality was evaluated using a 10-year-period of follow-up, and presented in Kaplan-Meier plots. A significant increase in copeptin level could be seen in the placebo group during the intervention period (from 9.4 pmol/L to 15.3 pmol/L), compared to the active treatment group. The difference between the groups was confirmed in the repeated measurement of variance analyses (P = 0.031) with less copeptin increase in the active treatment group. Furthermore, active treatment appeared to protect against cardiovascular death both in those with high and with low copeptin levels at inclusion. Less increase of MR-proADM could also be seen during the intervention in the active treatment group compared to controls (P = 0.026). Both in those having an MR-proADM level above or below median level, significantly less cardiovascular mortality could be seen in the active treatment group (P = 0.0001, and P = 0.04 respectively). In conclusion supplementation with selenium and coenzyme Q10 during four years resulted in less concentration of both copeptin and MR-proADM. A cardioprotective effect of the supplementation was registered, irrespective of the initial levels of these biomarkers, and this protection was recognized also after 10 years of observation.

Epigallocatechin-3-gallate induces human liver cancer HepG2 cell apoptosis and growth inhibition by suppressing phosphatidylinositol 3 kinase/protein kinase B signaling

AIM: To investigate the effect of epigallocatechin-3-gallate (EGCG) on cell apoptosis and proliferation in the human liver cancer cell line HepG2 and to explore the underlying mechanism.

METHODS: HepG2 cells in logarithmic growth phase were treated with different concentrations of EGCG (0, 10, 20, 40 µg/mL) for 48 h. MTT and flow cytometric analysis were used to evaluate the proliferation, membrane potential and apoptosis of HepG2 cells. The expression of phosphatidylinositol 3 kinase (PI3K), p-protein kinase B (p-AKT), AKT, BCL-2, Bax, pro-Caspase3, cleaved Caspase3, poly(ADP-ribose) polymerase (PARP), cleaved PARP and cytochrome C (CytC) in HepG2 cells was detected by Western blot.

RESULTS: EGCG treatment significantly decreased the cell proliferation, membrane potential and the expression of PI3K, p-AKT, cleaved PARP, cleaved Caspase3 and Bcl-2 in HepG2 cells, and increased cell apoptosis and the expression of pro-Caspase3, PARP, CytC and Bax. However, EGCG treatment had no significant influence on the expression of AKT.

CONCLUSION: EGCG induces cell apoptosis and growth inhibition in the human liver cancer cell line HepG2 possibly by suppressing PI3K/AKT signaling