Opioid receptors and cardioprotection - 'opioidergic conditioning' of the heart

Morphine timing-dependent modulation of TRPV1 phosphorylation correlates with differential morphine effects on myocardial ischemia/reperfusion injury

Opioids are used for pain relief in patients suffering from acute myocardial ischemia or infarction. Clinical and laboratory studies demonstrate that morphine treated patients or the experimental animal model suffering acute myocardial ischemia and reperfusion, may worsen myocardial viability. As transient receptor potential vanilloid 1 (TRPV1) plays important roles in pain sensation and cardio-protection, we query whether opioids may exacerbate myocardial viability via interaction with TRPV1 activity in the pain relief. We found the co-expressions of TRPV1 and opioid μ, δ and κ receptors in adult rat cardiomyocytes. Intravenous injection of morphine (0.3 mg/kg) at 20 min after induction of myocardial ischemia, in the rat model of acute myocardial ischemia and reperfusion, induced significant reduction of phosphorylated TRPV1 (p-TRPV1) in the ventricular myocardium and increase in serum cardiac troponin I (cTnI), compared with the ischemia/reperfusion controls (all P < 0.05). The effects of morphine were completely reversed by selective opioid μ, δ and κ receptor antagonists. While significant upregulation of p-TRPV1 (P < 0.05) and improvement of ±dP/dt max (all P < 0.05) were detected in the animals giving the same dose of morphine before induction of myocardial ischemia. The changes in p-TRPV1 correlate with the alterations of cTnI (r = -0.5840, P = 0.0283) and ±dP/dt max (r = 0.8084, P = 0.0005 and r = -0.8133, P = 0.0004, respectively). The findings of this study may indicate that potentiation and attenuation of TRPV1 sensitivity correlate with the improvement of the cardiac performance and the aggravation of myocardial viability, respectively, by giving morphine before and during myocardial ischemia and reperfusion.

Novel roles of κ-opioid receptor in myocardial ischemia-reperfusion injury

Acute heart attack is the primary cause of cardiovascular-related death worldwide. A common treatment is reperfusion of ischemic tissue, which can cause irreversible damage to the myocardium. The number of mitochondria in cardiomyocytes is large, which generate adenosine triphosphate (ATP) to sustain proper cardiac contractile function, and mitochondrial dysfunction plays a crucial role in cell death during myocardial ischemia-reperfusion, leading to an increasing number of studies investigating the impact of mitochondria on ischemia-reperfusion injury. The disarray of mitochondrial dynamics, excessive Ca2+ accumulation, activation of mitochondrial permeable transition pores, swelling of mitochondria, ultimately the death of cardiomyocyte are the consequences of ischemia-reperfusion injury. κ-opioid receptors can alleviate mitochondrial dysfunction, regulate mitochondrial dynamics, mitigate myocardial ischemia-reperfusion injury, exert protective effects on myocardium. The mechanism of κ-OR activation during myocardial ischemia-reperfusion to regulate mitochondrial dynamics and reduce myocardial ischemia-reperfusion injury will be discussed, so as to provide theoretical basis for the protection of ischemic myocardium.

Myocardial protection in cardiac surgery: a comprehensive review of current therapies and future cardioprotective strategies

Cardiac surgery with cardiopulmonary bypass results in global myocardial ischemia-reperfusion injury, leading to significant postoperative morbidity and mortality. Although cardioplegia is the cornerstone of intraoperative cardioprotection, a number of additional strategies have been identified. The concept of preconditioning and postconditioning, despite its limited direct clinical application, provided an essential contribution to the understanding of myocardial injury and organ protection. Therefore, physicians can use different tools to limit perioperative myocardial injury. These include the choice of anesthetic agents, remote ischemic preconditioning, tight glycemic control, optimization of respiratory parameters during the aortic unclamping phase to limit reperfusion injury, appropriate choice of monitoring to optimize hemodynamic parameters and limit perioperative use of catecholamines, and early reintroduction of cardioprotective agents in the postoperative period. Appropriate management before, during, and after cardiopulmonary bypass will help to decrease myocardial damage. This review aimed to highlight the current advancements in cardioprotection and their potential applications during cardiac surgery.

Cardiomyocyte-specific overexpression of GPR22 ameliorates cardiac injury in mice with acute myocardial infarction

BACKGROUND

The activation of G protein-coupled receptors (GPCR) signaling by external stimuli has been implicated in inducing cardiac stress and stress responses. GPR22 is an orphan GPCR expressed in brains and hearts, while its expression level is associated with cardiovascular damage in diabetes. Previous studies have suggested a protective role of GPR22 in mechanical cardiac stress, as loss of its expression increases susceptibility to heart failure post-ventricular pressure overload. However, the involvement and underlying signaling of GPR22 in cardiac stress response to ischemic stress remains unexplored.

METHODS

In this study, we used cultured cells and a transgenic mouse model with cardiomyocyte-specific GPR22 overexpression to investigate the impact of ischemic stress on GPR22 expression and to elucidate its role in myocardial ischemic injury. Acute myocardial infarction (AMI) was induced by left coronary artery ligation in eight-week-old male GPR22 transgenic mice, followed by histopathological and biochemical examination four weeks post-AMI induction.

RESULTS

GPR22 expression in H9C2 and RL-14 cells, two cardiomyocyte cell lines, was decreased by cobalt chloride (CoCl2) treatment. Similarly, reduced expression of myocardial GPR22 was observed in mice with AMI. Histopathological examinations revealed a protective effect of GPR22 overexpression in attenuating myocardial infarction in mice with AMI. Furthermore, myocardial levels of Bcl-2 and activation of PI3K-Akt signaling were downregulated by ischemic stress and upregulated by GPR22 overexpression. Conversely, the expression levels of caspase-3 and phosphorylated ERK1/2 in the infarcted myocardium were downregulated with GPR22 overexpression.

CONCLUSION

Myocardial ischemic stress downregulates cardiac expression of GPR22, whereas overexpression of GPR22 in cardiomyocytes upregulates Akt signaling, downregulates ERK activation, and mitigates ischemia-induced myocardial injury.

Long-term administration of morphine specifically alters the level of protein expression in different brain regions and affects the redox state

We investigated the changes in redox state and protein expression in selected parts of the rat brain induced by a 4 week administration of morphine (10 mg/kg/day). We found a significant reduction in lipid peroxidation that mostly persisted for 1 week after morphine withdrawal. Morphine treatment led to a significant increase in complex II in the cerebral cortex (Crt), which was accompanied by increased protein carbonylation, in contrast to the other brain regions studied. Glutathione levels were altered differently in the different brain regions after morphine treatment. Using label-free quantitative proteomic analysis, we found some specific changes in protein expression profiles in the Crt, hippocampus, striatum, and cerebellum on the day after morphine withdrawal and 1 week later. A common feature was the upregulation of anti-apoptotic proteins and dysregulation of the extracellular matrix. Our results indicate that the tested protocol of morphine administration has no significant toxic effect on the rat brain. On the contrary, it led to a decrease in lipid peroxidation and activation of anti-apoptotic proteins. Furthermore, our data suggest that long-term treatment with morphine acts specifically on different brain regions and that a 1 week drug withdrawal is not sufficient to normalize cellular redox state and protein levels.

Evaluating the association between opium abuse, blood lead levels, and the complexity of coronary artery disease

Opium abuse and exposure to heavy metals elevate the risk of coronary artery disease (CAD). Therefore, we aimed to determine the association between opium abuse and blood lead levels (BLLs) and the CAD complexity. We evaluated patients with acute coronary symptoms who underwent coronary angiography, and those with >50% stenosis in at least one of the coronary arteries were included. Furthermore, Synergy between PCI with Taxus and Cardiac Surgery I (SYNTAX I) score and BLLs were measured. Based on the opium abuse, 95 patients were subdivided into opium (45) and control (50) groups. Differences in demographics and CAD risk factors were insignificant between the two groups. The median BLLs were remarkably higher in the opium group than in controls (36 (35.7) and 20.5 μg/dL (11.45), respectively, p = 0.003). We also revealed no significant differences in SYNTAX score between the two groups (15.0 (9.0) and 17.5 (14.0), respectively, p = 0.28). Additionally, we found no significant correlation between BLLs and the SYNTAX scores (p = 0.277 and r = -0.113). Opium abuse was associated with high BLLs. Neither opium abuse nor high BLLs were correlated with the complexity of CAD. Further studies are warranted to establish better the relationship between opium abuse, BLLs, and CAD.

Influence of a chronic beta-blocker therapy on perioperative opioid consumption - a post hoc secondary analysis

BACKGROUND

Beta-blocker (BB) therapy plays a central role in the treatment of cardiovascular diseases. An increasing number of patients with cardiovascular diseases undergoe noncardiac surgery, where opioids are an integral part of the anesthesiological management. There is evidence to suggest that short-term intravenous BB therapy may influence perioperative opioid requirements due to an assumed cross-talk between G-protein coupled beta-adrenergic and opioid receptors. Whether chronic BB therapy could also have an influence on perioperative opioid requirements is unclear.

METHODS

A post hoc analysis of prospectively collected data from a multicenter observational (BioCog) study was performed. Inclusion criteria consisted of elderly patients (≥ 65 years) undergoing elective noncardiac surgery as well as total intravenous general anesthesia without the use of regional anesthesia and duration of anesthesia ≥ 60 min. Two groups were defined: patients with and without BB in their regular preopreative medication. The administered opioids were converted to their respective morphine equivalent doses. Multiple regression analysis was performed using the morphine-index to identify independent predictors.

RESULTS

A total of 747 patients were included in the BioCog study in the study center Berlin. 106 patients fulfilled the inclusion criteria. Of these, 37 were on chronic BB. The latter were preoperatively significantly more likely to have arterial hypertension (94.6%), chronic renal failure (27%) and hyperlipoproteinemia (51.4%) compared to patients without BB. Both groups did not differ in terms of cumulative perioperative morphine equivalent dose (230.9 (BB group) vs. 214.8 mg (Non-BB group)). Predictive factors for increased morphine-index were older age, male sex, longer duration of anesthesia and surgery of the trunk. In a model with logarithmised morphine index, only gender (female) and duration of anesthesia remained predictive factors.

CONCLUSIONS

Chronic BB therapy was not associated with a reduced perioperative opioid consumption.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov ( NCT02265263 ) on the 15.10.2014 with the principal investigator being Univ.-Prof. Dr. med. Claudia Spies.

The Role of Opioid Receptor Antagonists in Regulation of Blood Pressure and T-Cell Activation in Mice Selected for High Analgesia Induced by Swim Stress

Opioid peptides and their G protein-coupled receptors are important regulators within the cardiovascular system, implicated in the modulation of both heart and vascular functions. It is known that naloxone-an opioid antagonist-may exert a hypertensive effect. Recent experimental and clinical evidence supports the important role of inflammatory mechanisms in hypertension. Since opioids may play a role in the regulation of both blood pressure and immune response, we studied these two processes in our model. We aimed to evaluate the effect of selective and non-selective opioid receptor antagonists on blood pressure and T-cell activation in a mouse model of high swim stress-induced analgesia. Blood pressure was measured before and during the infusion of opioid receptor antagonists using a non-invasive tail-cuff measurement system. To assess the activation of T-cells, flow cytometry was used. We discovered that the non-selective antagonism of the opioid system by naloxone caused a significant elevation of blood pressure. The selective antagonism of μ and κ but not δ opioid receptors significantly increased systolic blood pressure. Subsequently, a brief characterization of T-cell subsets was performed. We found that the blockade of μ and δ receptors is associated with the increased expression of CD69 on CD4 T-cells. Moreover, we observed an increase in the central memory CD4 and central memory CD8 T-cell populations after the δ opioid receptor blockade. The antagonism of the μ opioid receptor increased the CD8 effector and central memory T-cell populations.

The Role of Endogenous Opioids in Cardioprotection

The opioid system involves opioid receptors (OPRs) and endogenous opioid peptides.This chapter will focus on the distribution of OPRs in the cardiovascular system, the expression pattern in the heart, the activation by opioid peptides, and the effects of OPRs activation with potential relevance in cardiovascular performance. In the heart, OPRs are co-expressed with beta adrenergic receptors (β-ARs) in the G-protein-coupled receptor (GPCR) superfamily, functionally cross-talk with β-Ars and modify catecholamine-induced effects. They are involved in cardiac contractility, energy metabolism, myocyte survival or death, vascular resistance. The effects of the opioid system in the regulation of systemic circulation at both the central and peripheral level are presented. The pathways are discussed under physiological (i.e., aging) and pathological conditions (atherosclerosis, heart failure, essential hypertension, ischemic stress). Stimulation of OPRs not only inhibits cardiac excitation-contraction coupling, but also protects the heart against hypoxic and ischemic injury. An enhanced sensitivity to opioids of endocrine organs and neuronal systems is operative in hypertensive patients. The opioid system can be pharmacologically engaged to selectively mimic these responses via cardiac and nervous signaling. The clinical opportunities for the use of cardioprotective effects of opioids require future investigations to provide more specific details of the impact on cardiac performance and electrophysiological properties.

Circular RNA circSMAD4 regulates cardiac fibrosis by targeting miR-671-5p and FGFR2 in cardiac fibroblasts

Heart failure is a leading cause of death and is often accompanied by activation of quiescent cardiac myofibroblasts, which results in cardiac fibrosis. In this study, we aimed to identify novel circular RNAs that regulate cardiac fibrosis. We applied transverse aortic constriction (TAC) for 1, 4, and 8 weeks in mice. RNA sequencing datasets were obtained from cardiac fibroblasts isolated by use of a Langendorff apparatus and then further processed by use of selection criteria such as differential expression and conservation in species. CircSMAD4 was upregulated by TAC in mice or by transforming growth factor (TGF)-β1 in primarily cultured human cardiac fibroblasts. Delivery of si-circSMAD4 attenuated myofibroblast activation and cardiac fibrosis in mice treated with isoproterenol (ISP). si-circSmad4 significantly reduced cardiac fibrosis and remodeling at 8 weeks. Mechanistically, circSMAD4 acted as a sponge against the microRNA miR-671-5p in a sequence-specific manner. miR-671-5p was downregulated during myofibroblast activation and its mimic form attenuated cardiac fibrosis. miR-671-5p mimic destabilized fibroblast growth factor receptor 2 (FGFR2) mRNA in a sequence-specific manner and interfered with the fibrotic action of FGFR2. The circSMAD4-miR-671-5p-FGFR2 pathway is involved in the differentiation of cardiac myofibroblasts and thereby the development of cardiac fibrosis.

Targeting the opioid remifentanil: Protective effects and molecular mechanisms against organ ischemia-reperfusion injury

Opioids are widely used in clinical practice by activating opioid receptors (OPRs), but their clinical application is limited by a series of side effects. Researchers have been making tremendous efforts to promote the development and application of opioids. Fortunately, recent studies have identified the additional effects of opioids in addition to anesthesia and analgesia, particularly in terms of organ protection against ischemia-reperfusion (I/R) injury, with unique advantages. I/R injury in vital organs not only leads to cell dysfunction and structural damage but also induces acute and chronic organ failure, even death. Early prevention and appropriate therapeutic targets for I/R injury are crucial for organ protection. Opioids have shown cardioprotective effects for over 20 years, especially remifentanil, a derivative of fentanyl, which is a new ultra-short-acting opioid analgesic widely used in clinical anesthesia induction and maintenance. In this review, we provide current knowledge about the physiological effects related to OPR-mediated organ protection, focusing on the protective effect and mechanism of remifentanil on I/R injury in the heart and other vital organs. Herein, we also explored the potential application of remifentanil in clinical I/R injury. These findings provide a theoretical basis for the use of remifentanil to inhibit or alleviate organ I/R injury during the perioperative period and provide insights for opioid-induced human organ protection and drug development.

Proenkephalin Levels and Its Determinants in Patients with End-Stage Kidney Disease Treated with Hemodialysis and Peritoneal Dialysis

Recently, proenkephalin A (PENK A) has been shown to reflect glomerular dysfunction and to predict new-onset acute kidney injury and heart failure. While previous studies have investigated PENK A as a biomarker in individuals with preserved renal function, PENK A concentration in patients with end-stage kidney disease (ESKD) was not investigated. Plasma PENK A concentration was assessed in 88 patients with ESKD treated with hemodialysis (HD) or peritoneal dialysis (PD), and its associations with kidney function and heart failure indicators were investigated. In HD patients, the difference in PENK A levels before and after hemodialysis, was measured and further assessed for an association with the type of HD membrane used. PENK A levels did not differ significantly between HD and PD patients. In HD patients, the median PENK A concentration was significantly higher before than after hemodialysis (1.368 vs. 2.061, p = 0.003). No correlation was found between PENK A level and urea (p = 0.192), eGFR (p = 0.922), dialysis vintage (p = 0.637), and residual urine output (p = 0.784). Heart failure (p = 0.961), EF (p = 0.361), and NT-proBNP (p = 0.949) were not associated with increased PENK A concentration. PENK A does not reflect renal function and cardiac status in patients with ESKD. Further research is required to establish the clinical utility of the new biomarker in patients with impaired kidney function.

Causal association between major depressive disorder and coronary heart disease: a two-sample bidirectional mendelian randomization study

BACKGROUND

Major depressive disorder (MDD) is a highly heterogeneous mental illness and a major public health problem worldwide. A large number of observational studies have demonstrated a clear association between MDD and coronary heart disease (CHD), and some studies have even suggested that the relationship is bidirectional. However, it was unknown whether any causal relationship existed between them and whether causality was bidirectional in such an instance. Thus, we aimed to determine whether there is a bidirectional causal relationship between major depressive disorders and coronary heart disease.

METHODS

Our two-sample Bidirectional Mendelian Randomization Study consisted of two parts: forward MR analysis regarded MDD as exposure and CHD as the outcome, and reverse MR analysis considered CHD as exposure and MDD as the outcome. Summary data on MDD and CHD were obtained from the IEU Open GWAS database. After screening criteria(P < [Formula: see text]), 47 MDD-associated SNPs and 39 CHD-associated SNPs were identified. The inverse-variance weighted (IVW) method, ME-Egger regression, and weighted median method were used to estimate causality. In addition, sensitivity methods, including the heterogeneity test, horizontal pleiotropy test, and leave-one-out method, were applied to ensure the robustness of causal estimation.

RESULTS

Based on the MR-Egger regression intercept test results, there did not appear to be any horizontal pleiotropy in this study (MDD: intercept = -0.0000376, P = 0.9996; CHD: intercept = -0.0002698, P = 0.920). Accordingly, IVW results suggested consistent estimates of causal effect values. The results showed that people with MDD increased the risk of CHD by 14.7% compared with those without MDD (OR = 1.147, 95%CI: 1.045-1.249, P = 0.009). But there was no direct evidence that CHD would increase the risk of MDD(OR = 1.008, 95%CI: 0.985-1.031, P = 0.490). The heterogeneity test and funnel plot showed no heterogeneity in 47 SNPs of MDD (Q = 42.28, [Formula: see text]=0, P = 0.629), but there was heterogeneity in 39 SNPs of CHD (Q = 62.48, [Formula: see text]=39.18%, P = 0.007). The leave-one-out method failed to identify instances where a single SNP was either biased toward or dependent on the causation.

CONCLUSION

Our study supports a one-way causal relationship between MDD and CHD, but there is no bidirectional causal relationship. MDD increases the risk of CHD, but there is no evidence that CHD increases the risk of MDD. Therefore, the influence of psychological factors should also be considered in the prevention and treatment of CHD. For MDD patients, it is necessary to prevent cardiovascular diseases.

Role of G-protein coupled receptors in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death globally, with CVDs accounting for nearly 30% of deaths worldwide each year. G-protein-coupled receptors (GPCRs) are the most prominent family of receptors on the cell surface, and play an essential regulating cellular physiology and pathology. Some GPCR antagonists, such as β-blockers, are standard therapy for the treatment of CVDs. In addition, nearly one-third of the drugs used to treat CVDs target GPCRs. All the evidence demonstrates the crucial role of GPCRs in CVDs. Over the past decades, studies on the structure and function of GPCRs have identified many targets for the treatment of CVDs. In this review, we summarize and discuss the role of GPCRs in the function of the cardiovascular system from both vascular and heart perspectives, then analyze the complex ways in which multiple GPCRs exert regulatory functions in vascular and heart diseases. We hope to provide new ideas for the treatment of CVDs and the development of novel drugs.

Outcomes of Patients with Opioid-Related Diagnoses in Acute Coronary Syndrome: a National Inpatient Sample-Based Analysis

BACKGROUND

Acute coronary syndrome (ACS) and opioid use are both major causes of morbidity and mortality globally. Although epidemiological studies point to increased risk of ACS in opioid users, in-hospital management and outcomes are unknown for this population when presenting with ACS. We sought to determine whether there are differences for in-hospital outcomes and management of ACS for those with and without opioid-related diagnoses (ORD).

METHODS AND RESULTS

From the National Inpatient Sample database, we extracted patients hospitalized between 2012 and 2016 for ACS. The primary independent variable was ORD by International Classification of Diseases, 9th and 10th Revision, codes. The primary outcome was in-hospital mortality; secondary outcomes were cardiac arrest, receipt of angiogram, and percutaneous coronary intervention (PCI). Statistical comparisons were performed using χ2 test and Student's t test. Multivariable logistic regression was performed to determine the independent association between ORD and outcomes of interest. Among the estimated 5.8 million admissions for ACS, the proportion of patients with ORD increased over the study period (p for trend < 0.01). Compared to patients without ORD presenting with ACS, patients with ORD were younger with fewer cardiovascular risk factors. Yet, in-hospital mortality was higher in patients with ORD presenting with ACS (AOR 1.36, 95% CI 1.26-1.48). Patients with ORD were more likely to experience in-hospital cardiac arrest (AOR 1.42, 95% CI 1.23-1.63) and less likely to undergo angiogram (AOR 0.42, 95% CI 0.38-0.45) or PCI (AOR 0.30, 95% CI 0.28-0.32).

CONCLUSION

Despite evidence of increased risk of mortality and cardiac arrest, patients with ORD admitted for ACS are less likely to receive ACS management.

Interaction of Cardiovascular Nonmodifiable Risk Factors, Comorbidities and Comedications With Ischemia/Reperfusion Injury and Cardioprotection by Pharmacological Treatments and Ischemic Conditioning

Preconditioning, postconditioning, and remote conditioning of the myocardium enhance the ability of the heart to withstand a prolonged ischemia/reperfusion insult and the potential to provide novel therapeutic paradigms for cardioprotection. While many signaling pathways leading to endogenous cardioprotection have been elucidated in experimental studies over the past 30 years, no cardioprotective drug is on the market yet for that indication. One likely major reason for this failure to translate cardioprotection into patient benefit is the lack of rigorous and systematic preclinical evaluation of promising cardioprotective therapies prior to their clinical evaluation, since ischemic heart disease in humans is a complex disorder caused by or associated with cardiovascular risk factors and comorbidities. These risk factors and comorbidities induce fundamental alterations in cellular signaling cascades that affect the development of ischemia/reperfusion injury and responses to cardioprotective interventions. Moreover, some of the medications used to treat these comorbidities may impact on cardioprotection by again modifying cellular signaling pathways. The aim of this article is to review the recent evidence that cardiovascular risk factors as well as comorbidities and their medications may modify the response to cardioprotective interventions. We emphasize the critical need for taking into account the presence of cardiovascular risk factors as well as comorbidities and their concomitant medications when designing preclinical studies for the identification and validation of cardioprotective drug targets and clinical studies. This will hopefully maximize the success rate of developing rational approaches to effective cardioprotective therapies for the majority of patients with multiple comorbidities. SIGNIFICANCE STATEMENT: Ischemic heart disease is a major cause of mortality; however, there are still no cardioprotective drugs on the market. Most studies on cardioprotection have been undertaken in animal models of ischemia/reperfusion in the absence of comorbidities; however, ischemic heart disease develops with other systemic disorders (e.g., hypertension, hyperlipidemia, diabetes, atherosclerosis). Here we focus on the preclinical and clinical evidence showing how these comorbidities and their routine medications affect ischemia/reperfusion injury and interfere with cardioprotective strategies.

Clinical outcomes of opioid administration in acute and chronic heart failure: A meta-analysis

BACKGROUND AND AIMS

Opioid use in heart failure (HF) management is controversial, and whether rapid symptomatic relief outweighs the risks of opioid use in HF remains unknown. This study aimed to explore the clinical outcomes of opioid administration in patients with acute or chronic HF.

METHODS

A systematic search for eligible studies was conducted in databases (MEDLINE, Scopus, Web of Science, EBSCO) and registries (ClinicalTrials.gov, WHO Clinical Trial Registry) until June 8, 2022. Odds ratios (ORs) or adjusted OR (aORs) and mean difference (MD) or standardized MD were quantified for binary and continuous outcomes, respectively. Meta-regression was performed using the restricted maximum likelihood method.

RESULTS

A total of 20 studies (154,736 participants) were included. In acute HF, opioid use presented a high risk for in-hospital mortality (OR = 2.35; 95% confidence interval (CI): 1.03-5.38; I² = 97%), invasive (OR = 2.78; 95%CI: 1.17-6.61; I² = 93%) and noninvasive (OR = 2.97; 95%CI: 1.06-8.28; I² = 95%) ventilations, intensive care unit admission (OR = 3.62; 95%CI: 3.11-4.21; I² = 6%), and inotrope use (OR = 2.54; 95%CI: 1.94-3.32; I² = 63%). In chronic HF New York Heart Association (NYHA) Class II/III, opioid use improved ventilatory efficiency (MD = -3.16; 95%CI: (-4.78)-(-1.54); I² = 0%), and exercise test duration (MD = 69.24; 95%CI: 10.11-128.37; I² = 89%).

CONCLUSIONS

Opioids are not recommended for acute HF management; however, they showed an advantage in exercise testing by improving ventilatory efficiency, chemosensitivity, and exercise test duration in stable patients with chronic HF NYHA Class II/III. Nonetheless, larger randomized controlled trials and individual patient-level data meta-analyses are warranted.

Induction of JAK2/STAT3 pathway contributes to protective effects of different therapeutics against myocardial ischemia/reperfusion

Insufficiency in coronary blood supply results in myocardial ischemia and consequently, various clinical syndromes and irreversible injuries. Myocardial damage occurs as a result of two processes during acute myocardial infarction (MI): ischemia and subsequent reperfusion. According to the available evidence, oxidative stress, excessive inflammation reaction, reactive oxygen species (ROS) generation, and apoptosis are crucial players in the pathogenesis of myocardial ischemia/reperfusion (IR) injury. There is emerging evidence that Janus tyrosine kinase 2 (JAK2) signal transducer and activator of the transcription 3 (STAT3) pathway offers cardioprotection against myocardial IR injury. This article reviews therapeutics that exert cardioprotective effects against myocardial IR injury through induction of JAK2/STAT3 pathway.

Impacts of opium addiction on patterns of angiographic findings in patients with acute coronary syndrome

Opium is one of the most abused substances in the Middle East. The effects of opium use on coronary artery disease (CAD) are a matter of debate. This study aimed to assess the association between opium use and angiographic findings as well as the complexity of CAD in patients with acute coronary syndrome (ACS) diagnosis. In this case–control study, all patients admitted for coronary angiography from 2019 to 2020 were evaluated. After applying the eligibility criteria, they were categorized into two groups opium and non-opium based on their history of opium use. Both groups were matched regarding the demographic features. The prevalence, location, and severity of obstruction of the vessels were compared between the non-opium and opium groups. The SYNTAX score was also calculated and compared between the two groups. The scores ≤ 22 are considered low risk and the higher scores are a non-low risk. P value < 0.05 is considered significant. A total of 170 patients with a mean age of 61.59 ± 9.07 years were finally enrolled in our study. Regarding the severity of vascular involvement, there was a significant difference between the non-opium and opium groups in LAD (P = 0.025), and PLV (P = 0.018) vessels. From the location points of view of obstructive coronary artery involved segments, only in the PDA (P = 0.006), and LCX (P = 0.004) vessels, a significant difference was observed. Moreover, 47.1% of opium and 30.6% of non-opium use group were in the non-low risk SYNTAX score classification which is a statistically significant difference between these two groups (P value = 0.048). Opium, as an independent risk factor for cardiovascular diseases, can have specific effects on angiographic findings in patients with acute coronary syndrome. Likewise, the complexity of CAD in opium users who undergo percutaneous coronary intervention is significantly higher.

Nociception monitors vs. standard practice for titration of opioid administration in general anesthesia: A meta-analysis of randomized controlled trials

Background

Nociception monitors are being increasingly used during surgery, but their effectiveness in guiding intraoperative opioid administration is still uncertain. This meta-analysis of randomized controlled trials (RCTs) aimed to compare the effectiveness of nociception monitors vs. standard practice for opioid administration titration during general anesthesia.

Methods

We searched the electronic databases of PubMed, EMBASE, Cochrane Library, Clinical Trial, and Web of Science from inception up to August 1, 2021, to identify relevant articles, and extracted the relevant data. Intraoperative opioid administration, extubation time, postoperative pain score, postoperative opioid consumption and postoperative nausea and vomiting (PONV) were compared between patients receiving nociception monitoring guidance and patients receiving standard management. The standardized mean difference (SMD), with 95% confidence interval (CI), was used to assess the significance of differences. The risk ratio (RR), with 95% CI, was used to assess the difference in incidence of PONV. Heterogeneity among the included trials was evaluated by the I² test. RevMan 5.3 software was used for statistical analysis.

Results

A total of 21 RCTs (with 1957 patients) were included in the meta-analysis. Intraoperative opioid administration was significantly lower in patients receiving nociception monitor-guided analgesia than in patients receiving standard management (SMD, −0.71; 95% CI, −1.07 to −0.36; P < 0.001). However, pain scores and postoperative opioid consumption were not significantly higher in the former group. Considerable heterogeneity was found among the studies (92%). Extubation time was significantly shorter (SMD, −0.22; 95% CI, −0.41 to −0.03; P = 0.02) and the incidence of PONV significantly lower (RR, 0.78; 95% CI, 0.61 to 1.00; P = 0.05) in patients receiving nociception monitoring guidance.

Conclusions

Intraoperative nociception monitoring guidance may reduce intraoperative opioid administration and appears to be a viable strategy for intraoperative titration of opioids.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=273619, identifier: CRD42019129776.

Inhibiting Succinate Release Worsens Cardiac Reperfusion Injury by Enhancing Mitochondrial Reactive Oxygen Species Generation

Background

The metabolite succinate accumulates during cardiac ischemia. Within 5 minutes of reperfusion, succinate returns to baseline levels via both its release from cells and oxidation by mitochondrial complex II. The latter drives reactive oxygen species (ROS) generation and subsequent opening of the mitochondrial permeability transition (PT) pore, leading to cell death. Targeting succinate dynamics (accumulation/oxidation/release) may be therapeutically beneficial in cardiac ischemia–reperfusion (IR) injury. It has been proposed that blocking MCT1 (monocarboxylate transporter 1) may be beneficial in IR injury, by preventing succinate release and subsequent engagement of downstream inflammatory signaling pathways. In contrast, herein we hypothesized that blocking MCT1 would retain succinate in cells, exacerbating ROS generation and IR injury.

Methods and Results

Using the mitochondrial ROS probe mitoSOX and a custom‐built murine heart perfusion rig built into a spectrofluorometer, we measured ROS generation in situ during the first moments of reperfusion. We found that acute MCT1 inhibition enhanced mitochondrial ROS generation at reperfusion and worsened IR injury (recovery of function and infarct size). Both of these effects were abrogated by tandem inhibition of mitochondrial complex II, suggesting that succinate retention worsens IR because it drives more mitochondrial ROS generation. Furthermore, using the PT pore inhibitor cyclosporin A, along with monitoring of PT pore opening via the mitochondrial membrane potential indicator tetramethylrhodamine ethyl ester, we herein provide evidence that ROS generation during early reperfusion is upstream of the PT pore, not downstream as proposed by others. In addition, pore opening was exacerbated by MCT1 inhibition.

Conclusions

Together, these findings highlight the importance of succinate dynamics and mitochondrial ROS generation as key determinants of PT pore opening and IR injury outcomes.

Genetic liability for prescription opioid use and risk of cardiovascular diseases: a multivariable Mendelian randomization study

BACKGROUND AND AIMS

Observational studies have yielded conflicting results on the association of prescription opioid use (POU) with the risk of cardiovascular diseases (CVD). Residual confounding and potential reverse causality are inevitable in such conventional observational studies. This study used Mendelian randomization (MR) design to estimate the causal effect of POU on the risk of CVD, including coronary heart disease (CHD), myocardial infarction (MI) and ischemic stroke (IS), as well as their common risk factors.

DESIGN

We estimated the causal effect of genetic liability for POU on CVD in a two-sample MR framework. Complementary sensitivity analyses were conducted to test the robustness of our results.

SETTING

Genome-wide association studies (GWAS) that were based on predominantly European ancestry.

PARTICIPANTS

The sample sizes of the GWAS used in this study ranged from 69 033 to 757 601 participants.

MEASUREMENTS

Genetic variants predictive of the POU and their corresponding summary-level information in the outcomes were retrieved and extracted from the respective GWAS.

FINDINGS

Using univariable MR, we found evidence for a causal effect of genetic liability for POU on an increased risk of CHD [odds ratio (OR) = 1.09; 95% confidence interval (CI) = 1.02-1.16; P = 0.008] and MI (OR = 1.13; 95% CI = 1.04-1.22; P = 0.002). In multivariable MR, the association remained after accounting for comorbid pain conditions, but was attenuated with adjustment for potential mediators, including body mass index (BMI), waist circumference (WC) and type 2 diabetes (T2D).

CONCLUSION

Mendelian randomization estimates provide robust evidence for the causal effects of genetic liability for prescription opioid use on an increased risk of coronary heart disease and myocardial infarction, which might be mediated by obesity-related traits.

Naltrexone alters cardiovascular function following acute forced swimming in mice

Purpose

Naltrexone (NTX) is an opioid antagonist that can reverse the physiological effects of opioid receptors when bound. Opioid receptors have been found to play a role in cardiovascular (CV) function, and thus, binding of NTX may alter CV activity at rest and in response to acute and chronic exercise (EX). We hypothesized that opioid receptor blockade will alter the typical CV responses following acute EX.

Methods

We assessed the effects of opioid receptor blockade on CV function via echocardiography in mice following an acute bout of forced swimming (FSw), a model of rodent EX. We administered opioid receptor antagonist, NTX, or saline in mice before FSw and in the absence of an FSw perturbation. Furthermore, we assessed how NTX can influence maximal EX capacity on a rodent treadmill.

Results

Our data shows that NTX administration does not decrease maximal EX capacity in mice (P > 0.05). However, NTX attenuated cardiac output following FSw (FSw = 52.5 ± 2.5 ml/min vs. FSw + NTX = 32.7 ± 5.2 ml/min; P < 0.05) when compared with saline control (33.5 ± 3.8 ml/min). Further, the administration of NTX in the non-EX condition significantly (P < 0.05) reduced ejection fraction.

Conclusion

These data suggest that normal opioid receptor activation is necessary for typical CV function following FSw.

Effects of nalbuphine on the cardiotoxicity of ropivacaine in rats

When combined with nalbuphine, local anesthetics show a longer duration of nerve block without increasing complications. However, no evidence is available concerning the effect of nalbuphine on the cardiotoxicity of local anesthetics. The objective of this work is to investigate whether nalbuphine pretreatment can increase the lethal dose threshold of ropivacaine in rats. Anesthetized Sprague Dawley rats were pretreated with different doses of nalbuphine (0.4, 0.8, 1.5, 3.0, 5.0 mg/kg) or NS (normal saline, negative control) or 30% LE (lipid emulsion, positive control) 2 ml/kg/min for 5 min (n = 6). Then 0.5% ropivacaine was infused at a rate of 2.5 mg/kg/min until asystole occurs. Time of arrhythmia, 50% mean arterial pressure- and 50% heart rate-reduction, and asystole were recorded, and ropivacaine doses were calculated. Nalbuphine (0.4-5.0 mg/kg) did not affect ropivacaine-induced arrhythmia, 50% mean arterial pressure-reduction and 50% heart rate-reduction, and asystole in rats compared with NS pre-treatment. The asystole dose threshold (in milligrams per kilogram) of group LE was higher than that of group NS (NS 28.25(6.32) vs. LE, 41.58(10.65); P = 0.04; 95% confidence interval 0.23 to 26.45), while thresholds of arrhythmia, 50% mean arterial pressure-reduction, and 50% heart rate-reduction were not affected by LE. Nalbuphine doses of 0.4-5.0 mg/kg pretreatment did not increase the threshold of ropivacaine cardiotoxicity compared with NS control; 30% LE increases the lethal dose threshold of ropivacaine in rats.

Modification of Ischemia/Reperfusion-Induced Alterations in Subcellular Organelles by Ischemic Preconditioning

It is now well established that ischemia/reperfusion (I/R) injury is associated with the compromised recovery of cardiac contractile function. Such an adverse effect of I/R injury in the heart is attributed to the development of oxidative stress and intracellular Ca²⁺-overload, which are known to induce remodeling of subcellular organelles such as sarcolemma, sarcoplasmic reticulum, mitochondria and myofibrils. However, repeated episodes of brief periods of ischemia followed by reperfusion or ischemic preconditioning (IP) have been shown to improve cardiac function and exert cardioprotective actions against the adverse effects of prolonged I/R injury. This protective action of IP in attenuating myocardial damage and subcellular remodeling is likely to be due to marked reductions in the occurrence of oxidative stress and intracellular Ca²⁺-overload in cardiomyocytes. In addition, the beneficial actions of IP have been attributed to the depression of proteolytic activities and inflammatory levels of cytokines as well as the activation of the nuclear factor erythroid factor 2-mediated signal transduction pathway. Accordingly, this review is intended to describe some of the changes in subcellular organelles, which are induced in cardiomyocytes by I/R for the occurrence of oxidative stress and intracellular Ca²⁺-overload and highlight some of the mechanisms for explaining the cardioprotective effects of IP.

Multi-Omics Characterization of a Human Stem Cell-Based Model of Cardiac Hypertrophy

Cardiac hypertrophy is an important and independent risk factor for the development of cardiac myopathy that may lead to heart failure. The mechanisms underlying the development of cardiac hypertrophy are yet not well understood. To increase the knowledge about mechanisms and regulatory pathways involved in the progression of cardiac hypertrophy, we have developed a human induced pluripotent stem cell (hiPSC)-based in vitro model of cardiac hypertrophy and performed extensive characterization using a multi-omics approach. In a series of experiments, hiPSC-derived cardiomyocytes were stimulated with Endothelin-1 for 8, 24, 48, and 72 h, and their transcriptome and secreted proteome were analyzed. The transcriptomic data show many enriched canonical pathways related to cardiac hypertrophy already at the earliest time point, e.g., cardiac hypertrophy signaling. An integrated transcriptome–secretome analysis enabled the identification of multimodal biomarkers that may prove highly relevant for monitoring early cardiac hypertrophy progression. Taken together, the results from this study demonstrate that our in vitro model displays a hypertrophic response on both transcriptomic- and secreted-proteomic levels. The results also shed novel insights into the underlying mechanisms of cardiac hypertrophy, and novel putative early cardiac hypertrophy biomarkers have been identified that warrant further investigation to assess their potential clinical relevance.

CARDIOPROTECTIVE EFFECT OF ENKEPHALINS UNDER IMMOBILIZATION STRESS

Objective: The aim of this study was to investigate the cardioprotective effect of dalargin, a synthetic leu-enkephalin. Methods: The induction of myocardial infarction in rats, which were kept on a diet with excess fat and calcium/sodium salts for two months, by the use of immobilization stress. The experimental results indicated that the applied model allowed to induce the development of myocardial infarction within one three days, which was confirmed by electrocardiography, enzyme-linked immunosorbent assay and histological examination. Results: Pre-treatment of rats with dalargin had no prevented myocardial infarction, however, it increased the resistance to immobilization stress and reduced infarction-induced myocardial lesions. Simultaneous administration of naloxone, an opiate receptor antagonist, together with dalargin eliminated its cardioprotective effect in experimental animals. Conclusion: The use of synthetic leu-enkephalin dalargin significantly reduced the risk of myocardial infarction caused by excessive neuromuscular stress. The dalargin effect on the myocardium was mediated by opiate receptors.

Knock-In Mouse Models to Investigate the Functions of Opioid Receptors in vivo

Due to their low expression levels, complex multi-pass transmembrane structure, and the current lack of highly specific antibodies, the assessment of endogenous G protein-coupled receptors (GPCRs) remains challenging. While most of the research regarding their functions was performed in heterologous systems overexpressing the receptor, recent advances in genetic engineering methods have allowed the generation of several unique mouse models. These animals proved to be useful to investigate numerous aspects underlying the physiological functions of GPCRs, including their endogenous expression, distribution, interactome, and trafficking processes. Given their significant pharmacological importance and central roles in the nervous system, opioid peptide receptors (OPr) are often referred to as prototypical receptors for the study of GPCR regulatory mechanisms. Although only a few GPCR knock-in mouse lines have thus far been generated, OPr are strikingly well represented with over 20 different knock-in models, more than half of which were developed within the last 5 years. In this review, we describe the arsenal of OPr (mu-, delta-, and kappa-opioid), as well as the opioid-related nociceptin/orphanin FQ (NOP) receptor knock-in mouse models that have been generated over the past years. We further highlight the invaluable contribution of such models to our understanding of the in vivo mechanisms underlying the regulation of OPr, which could be conceivably transposed to any other GPCR, as well as the limitations, future perspectives, and possibilities enabled by such tools.

Comparison of effects of sevoflurane versus propofol on left ventricular longitudinal global and regional strain in patients undergoing on-pump coronary artery bypass grafting

Background:

Assessment of myocardial deformation by quantifying peak systolic longitudinal strain (PSLS) is a sensitive and robust index to detect subclinical myocardial dysfunction. We hypothesize that sevoflurane by virtue of anesthetic preconditioning preserves myocardial function better than propofol.

Aims:

The authors have assessed the effects of sevoflurane and propofol on global longitudinal strain (GLS) as a primary outcome in patients undergoing on-pump coronary artery bypass grafting. Our secondary aim was to assess the pattern of regional distribution of segmental PSLS between the groups.

Materials and Methods:

Fifty patients with normal left ventricular function undergoing coronary artery bypass grafting were analyzed in this prospective observational study. Consecutive patients received either propofol (P) or sevoflurane (S) anesthesia.

Measurements:

Trans-esophageal echocardiographic images (mid-esophageal four-chamber, two-chamber, and three-chamber (long-axis)) were recorded during the precardiopulmonary bypass (CPB) and post-CPB period. Strain analysis (GLS/segmental PSLS) was done offline by investigators blinded to the study. The inotropic score, duration of inotropic support, and mechanical ventilation required were recorded.

Results:

Following cardiopulmonary bypass and coronary revascularization, GLS reduced significantly in both the groups (P < 0.05). In the S-group, significant reduction in segmental strain was observed only in apical segments including apex, whereas in P-group significant reduction in segmental strain was seen in mid- and apical segments. The postoperative VIS, duration of inotropes/vasopressor required, and mechanical ventilation were similar in both the groups.

Conclusions:

There are no significant differences in global left ventricular function as assessed by GLS between patients anesthetized with sevoflurane or propofol. However, regional PSLS was better preserved in the S-group compared to P-group.

New targets of morphine postconditioning protection of the myocardium in ischemia/reperfusion injury: Involvement of HSP90/Akt and C5a/NF-κB

Background

Activation of the complement component 5a (C5a) and nuclear factor κB (NF-κB) signaling is an important feature of myocardial ischemia/reperfusion (I/R) injury and recent studies show that morphine postconditioning (MP) attenuates the myocardial injury. However, the mediating cardioprotective mechanisms remain unclear. The present study explores the role and interaction of heat shock protein 90 (HSP90), Akt, C5a, and NF-κB in MP-induced cardioprotection.

Methods

Male Sprague Dawley rats (n = 160) were randomized into eight groups (n = 20 per group). Rats in the sham group underwent thoracotomy, passing the ligature through the heart but without tying it (150 min), and the other seven groups were subjected to 30 min of anterior descending coronary artery occlusion followed by 2 h of reperfusion and the following treatments: I/R (30 min of ischemia and followed by 2 h of reperfusion); ischemic postconditioning (IPostC, 30 s of ischemia altered with 30 s of reperfusion, repeated for three cycles, and followed by reperfusion for 2 h); MP (0.3 mg/kg morphine administration 10 min before reperfusion); MP combined with the HSP90 inhibitor geldanamycin (GA, 1 mg/kg); MP combined with the Akt inhibitor GSK-690693 (GSK, 20 mg/kg); and MP combined with the C5a inhibitor PMX205 (PMX, 1 mg/kg/day, administration via drinking water for 28 days) and MP combined with the NF-κB inhibitor EVP4593 (QNZ, 1 mg/kg). All inhibitors were administered 10 min before morphine and followed by 2 h reperfusion.

Results

MP significantly reduced the I/R-induced infarct size, the apoptosis, and the release of cardiac troponin I, lactate dehydrogenase (LDH), and creatine kinase-MB. These beneficial effects were accompanied by increased expression of HSP90 and p-Akt, and decreased expression of C5a, NF-κB, tumor necrosis factor α, interleukin-1β, and intercellular cell adhesion molecule 1. However, HSP90 inhibitor GA or Akt inhibitor GSK increased the expression of C5a and NF-κB and prevented MP-induced cardioprotection. Furthermore, GA inhibited the MP-induced upregulation of p-Akt, while GSK did not affect HSP90, indicating that p-Akt acts downstream of HSP90 in MP-induced cardioprotection. In addition, C5a inhibitor PMX enhanced the MP-induced downregulation of NF-κB, while NF-κB inhibitor QNZ had no effect on C5a, indicating that the C5a/NF-κB signaling pathway is involved in MP-induced cardioprotection.

Conclusion

HSP90 is critical for MP-mediated cardioprotection possibly by promoting the phosphorylation of Akt and inhibiting the activation of C5a and NF-κB signaling and the subsequent myocardial inflammation, ultimately attenuating the infarct size and cardiomyocyte apoptosis.

Differential barcoding of opioid receptors trafficking

Over the past several years, studies have highlighted the δ-opioid receptor (DOPr) as a promising therapeutic target for chronic pain management. While exhibiting milder undesired effects than most currently prescribed opioids, its specific agonists elicit effective analgesic responses in numerous animal models of chronic pain, including inflammatory, neuropathic, diabetic, and cancer-related pain. However, as compared with the extensively studied μ-opioid receptor, the molecular mechanisms governing its trafficking remain elusive. Recent advances have denoted several significant particularities in the regulation of DOPr intracellular routing, setting it apart from the other members of the opioid receptor family. Although they share high homology, each opioid receptor subtype displays specific amino acid patterns potentially involved in the regulation of its trafficking. These precise motifs or "barcodes" are selectively recognized by regulatory proteins and therefore dictate several aspects of the itinerary of a receptor, including its anterograde transport, internalization, recycling, and degradation. With a specific focus on the regulation of DOPr trafficking, this review will discuss previously reported, as well as potential novel trafficking barcodes within the opioid and nociceptin/orphanin FQ opioid peptide receptors, and their impact in determining distinct interactomes and physiological responses.

Pharmacological Conditioning of the Heart: An Update on Experimental Developments and Clinical Implications

The aim of pharmacological conditioning is to protect the heart against myocardial ischemia-reperfusion (I/R) injury and its consequences. There is extensive literature that reports a multitude of different cardioprotective signaling molecules and mechanisms in diverse experimental protocols. Several pharmacological agents have been evaluated in terms of myocardial I/R injury. While results from experimental studies are immensely encouraging, translation into the clinical setting remains unsatisfactory. This narrative review wants to focus on two aspects: (1) give a comprehensive update on new developments of pharmacological conditioning in the experimental setting concentrating on recent literature of the last two years and (2) briefly summarize clinical evidence of these cardioprotective substances in the perioperative setting highlighting their clinical implications. By directly opposing each pharmacological agent regarding its recent experimental knowledge and most important available clinical data, a clear overview is given demonstrating the remaining gap between basic research and clinical practice. Finally, future perspectives are given on how we might overcome the limited translatability in the field of pharmacological conditioning.

Activation of the δ opioid receptor relieves cerebral ischemic injury in rats via EGFR transactivation

Delta opioids are thought to relieve ischemic injury and have tissue-protective properties. However, the detailed mechanisms of delta opioids have not been well identified. Receptor tyrosine kinases (RTKs), such as epidermal growth factor receptor (EGFR), have been shown to mediate downstream signals of δ opioid receptor (δOR) activation through the metalloproteinase (MMP)-dependent EGF-like growth factor (HB-EGF) excretion pathway, which is called transactivation. In this study, to investigate the role of EGFR in δOR-induced anti-ischemic effects in the brain, we applied the middle cerebral artery occlusion (MCAO) model followed by reperfusion to mimic ischemic stroke injury in rats. Pre-treatment with the δOR agonist [D-ala², D-leu⁵] enkephalin (DADLE) improved the neurologic deficits and the decreased infarct volume caused by cerebral ischemia/reperfusion injury, which were blocked by the EGFR inhibitor AG1478 and the MMP inhibitor GM6001, respectively. Further results indicated that DADLE activated EGFR, Akt and ERK1/2 and upregulated EGFR expression in the hippocampus in a time-dependent manner, which were inhibited by AG1478 and GM6001. The enzyme-linked immunosorbent assay (ELISA) results showed that δOR activation led to an increase in HB-EGF release, but HB-EGF in tissue was downregulated at the mRNA and protein levels. Moreover, this protective action caused by δOR agonists may involve attenuated hippocampal cellular apoptosis. Overall, these results demonstrate that MMP-mediated transactivation of EGFR is essential for δOR agonist-induced MCAO/reperfusion injury relief. These findings provide a potential molecular mechanism for the neuroprotective property of δOR and may add new insight into mitigating or preventing injury.

Chronic Naltrexone Therapy Is Associated with Improved Cardiac Function in Volume Overloaded Rats

PURPOSE

Myocardial opioid receptors were demonstrated in animals and humans and seem to colocalize with membranous and sarcolemmal calcium channels of the excitation-contraction coupling in the left ventricle (LV). Therefore, this study investigated whether blockade of the cardiac opioid system by naltrexone would affect cardiac function and neurohumoral parameters in Wistar rats with volume overload-induced heart failure.

METHODS

Volume overload in Wistar rats was induced by an aortocaval fistula (ACF). Left ventricular cardiac opioid receptors were identified by immunohistochemistry and their messenger ribonucleic acid (mRNA) as well as their endogenous ligand mRNA quantified by real-time polymerase chain reaction (RT-PCR). Following continuous delivery of either the opioid receptor antagonist naltrexone or vehicle via minipumps (n = 5 rats each), hemodynamic and humoral parameters were assessed 28 days after ACF induction. Sham-operated animals served as controls.

RESULTS

In ACF rats mu-, delta-, and kappa-opioid receptors colocalized with voltage-gated L-type Ca2+ channels in left ventricular cardiomyocytes. Chronic naltrexone treatment of ACF rats reduced central venous pressure (CVP) and left ventricular end-diastolic pressure (LVEDP), and improved systolic and diastolic left ventricular functions. Concomitantly, rat brain natriuretic peptide (rBNP-45) and angiotensin-2 plasma concentrations which were elevated during ACF were significantly diminished following naltrexone treatment. In parallel, chronic naltrexone significantly reduced mu-, delta-, and kappa-opioid receptor mRNA, while it increased the endogenous opioid peptide mRNA compared to controls.

CONCLUSION

Opioid receptor blockade by naltrexone leads to improved LV function and decreases in rBNP-45 and angiotensin-2 plasma levels. In parallel, naltrexone resulted in opioid receptor mRNA downregulation and an elevated intrinsic tone of endogenous opioid peptides possibly reflecting a potentially cardiodepressant effect of the cardiac opioid system during volume overload.

[Perioperative cardioprotection - From bench to bedside : Current experimental evidence and possible reasons for the limited translation into the clinical setting]

Hintergrund

Ziel der perioperativen Kardioprotektion ist es, die Auswirkungen eines Ischämie- und Reperfusionsschadens zu minimieren. Aus anästhesiologischer Sicht spielt dieser Aspekt insbesondere in der Herzchirurgie bei Patienten mit Einsatz der Herz-Lungen-Maschine, aber auch allgemein bei längerfristigen hypotensiven Phasen oder perioperativen ischämischen Ereignissen im nichtkardiochirurgischen Setting eine wichtige Rolle. Im Laufe der letzten Jahre konnten diverse pharmakologische sowie nichtpharmakologische Strategien der Kardioprotektion identifiziert werden. Die Ergebnisse von Studien an isoliertem Gewebe sowie von tierexperimentellen In-vivo-Studien sind vielversprechend. Eine Translation dieser kardioprotektiven Strategien in die klinische Praxis ist bislang jedoch nicht gelungen. Große klinische Studien konnten keine signifikante Verbesserung des Outcome der Patienten zeigen.

Ziel der Arbeit

Dieser Übersichtsartikel gibt einen Überblick über die aktuelle experimentelle Evidenz pharmakologischer und nichtpharmakologischer Kardioprotektion. Außerdem sollen mögliche Gründe für die limitierte Translation diskutiert werden. Schließlich werden Möglichkeiten aufgezeigt, wie der Schritt „from bench to bedside“ in Zukunft doch noch gelingen könnte.

Material und Methoden

Narrative Übersichtsarbeit.

Ergebnisse und Diskussion

Trotz der vielversprechenden präklinischen experimentellen Ansätze zum Thema Kardioprotektion besteht nach wie vor eine große Diskrepanz zu den Ergebnissen aus großen klinischen Studien in der perioperativen Phase. Mögliche Gründe für die limitierte Translation könnten insbesondere Komorbiditäten und Komedikationen, die Wahl des Anästhesieverfahrens, aber auch die Wahl des Studiendesigns sein. Eine sorgfältige Studienplanung mit Berücksichtigung der genannten Probleme sowie ein simultaner Einsatz mehrerer kardioprotektiver Strategien mit dem Ziel eines additiven bzw. synergistischen Effekts stellen mögliche Ansätze für die Zukunft dar.

Fentanyl impairs but ketamine preserves the microcirculatory response to hemorrhage

BACKGROUND

Peripheral vasoconstriction is the most critical compensating mechanism following hemorrhage to maintain blood pressure. On the battlefield, ketamine rather than opioids is recommended for pain management in case of hemorrhage, but effects of analgesics on compensatory vasoconstriction are not defined. We hypothesized that fentanyl impairs but ketamine preserves the peripheral vasoconstriction and blood pressure compensation following hemorrhage.

METHOD

Sprague-Dawley rats (11-13 weeks) were randomly assigned to control (saline vehicle), fentanyl, or ketamine-treated groups with or without hemorrhage (n = 8 or 9 for each group). Rats were anesthetized with Inactin (i.p. 10 mg/100 g), and the spinotrapezius muscles were prepared for microcirculatory observation. Arteriolar arcades were observed with a Nikon microscope, and vessel images and arteriolar diameters were recorded by using Nikon NIS Elements Imaging Software (Nikon Instruments Inc. NY). After baseline perimeters were recorded, the arterioles were topically challenged with saline, fentanyl, or ketamine at concentrations relevant to intravenous analgesic doses to determine direct vasoactive effects. After arteriolar diameters returned to baseline, 30% of total blood volume was removed in 25 minutes. Ten minutes after hemorrhage, rats were intravenously injected with an analgesic dose of fentanyl (0.6 μg/100 g), ketamine (0.3 mg/100 g), or a comparable volume of saline. For each drug or vehicle administration, the total volume injected was 0.1 mL/100 g. Blood pressure, heart rate, and arteriolar responses were monitored for 40 minutes.

RESULTS

Topical fentanyl-induced vasodilation (17 ± 2%), but ketamine caused vasoconstriction (-15 ± 4%, p < 0.01). Following hemorrhage, intravenous ketamine did not affect blood pressure or respiratory rate, while fentanyl induced a slight and transient (<5 minutes, p = 0.03 vs. saline group) decrease in blood pressure, with a profound and prolonged suppression in respiratory rate (>10 minutes, with a peak inhibition of 57 ± 8% of baseline, p < 0.01). The compensatory vasoconstriction observed after hemorrhage was not affected by ketamine treatment. However, after fentanyl injection, although changes in blood pressure were transiently present, arteriolar constriction to hemorrhage was absent and replaced with a sustained vasodilation (78 ± 25% to 36 ± 22% of baseline during the 40 minutes after injection, p < 0.01).

CONCLUSION

Ketamine affects neither systemic nor microcirculatory compensatory responses to hemorrhage, providing preclinical evidence that ketamine may help attenuate adverse physiological consequences associated with opioids following traumatic hemorrhage. Microcirculatory responses are more sensitive than systemic response for evaluation of hemodynamic stability during procedures associated with pain management.

Perioperative Cardioprotection: General Mechanisms and Pharmacological Approaches

Cardioprotection encompasses a variety of strategies protecting the heart against myocardial injury that occurs during and after inadequate blood supply to the heart during myocardial infarction. While restoring reperfusion is crucial for salvaging myocardium from further damage, paradoxically, it itself accounts for additional cell death-a phenomenon named ischemia/reperfusion injury. Therefore, therapeutic strategies are necessary to render the heart protected against myocardial infarction. Ischemic pre- and postconditioning, by short periods of sublethal cardiac ischemia and reperfusion, are still the strongest mechanisms to achieve cardioprotection. However, it is highly impractical and far too invasive for clinical use. Fortunately, it can be mimicked pharmacologically, for example, by volatile anesthetics, noble gases, opioids, propofol, dexmedetomidine, and phosphodiesterase inhibitors. These substances are all routinely used in the clinical setting and seem promising candidates for successful translation of cardioprotection from experimental protocols to clinical trials. This review presents the fundamental mechanisms of conditioning strategies and provides an overview of the most recent and relevant findings on different concepts achieving cardioprotection in the experimental setting, specifically emphasizing pharmacological approaches in the perioperative context.

Pupillometry pain index decreases intraoperative sufentanyl administration in cardiac surgery: a prospective randomized study

Pupillometry has proven effective for the monitoring of intraoperative analgesia in non-cardiac surgery. We performed a prospective randomized study to evaluate the impact of an analgesia-guided pupillometry algorithm on the consumption of sufentanyl during cardiac surgery. Fifty patients were included prior to surgery. General anesthesia was standardized with propofol and target-controlled infusions of sufentanyl. The standard group consisted of sufentanyl target infusion left to the discretion of the anesthesiologist. The intervention group consisted of sufentanyl target infusion based on the pupillary pain index. The primary outcome was the total intraoperative sufentanyl dose. The total dose of sufentanyl was lower in the intervention group than in the control group and (55.8 µg [39.7–95.2] vs 83.9 µg [64.1–107.0], p = 0.04). During the postoperative course, the cumulative doses of morphine (mg) were not significantly different between groups (23 mg [15–53] vs 24 mg [17–46]; p = 0.95). We found no significant differences in chronic pain at 3 months between the 2 groups (0 (0%) vs 2 (9.5%) p = 0.49). Overall, the algorithm based on the pupillometry pain index decreased the dose of sufentanyl infused during cardiac surgery.

Clinical trial number: NCT03864016.

Morphine and myocardial ischaemia-reperfusion

Coronary heart disease (CHD) is a cardiovascular disease with high mortality and disability worldwide. The main pathological manifestation of CHD is myocardial injury due to ischaemia-reperfusion, resulting in the death of cardiomyocytes (apoptosis and necrosis) and the occurrence of cardiac failure. Morphine is a nonselective opioid receptor agonist that has been commonly used for analgesia and to treat ischaemic heart disease. The present review focused on morphine-induced protection in an animal model of myocardial ischaemia-reperfusion and chronic heart failure and the effects of morphine on ST segment elevation myocardial infarction (STEMI) patients who underwent pre-primary percutaneous coronary intervention (pre-PPCI) or PPCI. The signalling pathways involved are also briefly described.

Post-infarct morphine treatment reduces apoptosis and myofibroblast density in a rat model of cardiac ischemia-reperfusion

Following myocardial ischemia, the cardiac tissue undergoes both, physiological and pathological changes to compensate the initial loss of function. Long-term continuous adjustments often take a drastic picture indicated by deteriorated ventricular function. Morphine is commonly used for rescuing patients suffering a heart attack. Recent results from our laboratory showed the anti-remodeling potential of morphine. Here, we explored the effect of morphine treatment on gelatinolytic activity, apoptosis and myofibroblast density. The male Sprague - Dawley rats underwent ischemia via ligation of left anterior descending coronary artery and received morphine (3 mg/kg; i.p.) for five consecutive days. Seven days post-MI, morphine led to significant reduction in MMP - 2 activity, apoptotic cell death and fibroblast density. Morphine also reduced MI-induced rise in serum pro-oxidant antioxidant balance and nitrite levels on day 28th following the surgery. These results provide mechanistic insight for morphine - induced anti-remodeling effects.

Effects of the Delta Opioid Receptor Agonist DADLE in a Novel Hypoxia-Reoxygenation Model on Human and Rat-Engineered Heart Tissue: A Pilot Study

Intermittent hypoxia and various pharmacological compounds protect the heart from ischemia reperfusion injury in experimental approaches, but the translation into clinical trials has largely failed. One reason may lie in species differences and the lack of suitable human in vitro models to test for ischemia/reperfusion. We aimed to develop a novel hypoxia-reoxygenation model based on three-dimensional, spontaneously beating and work performing engineered heart tissue (EHT) from rat and human cardiomyocytes. Contractile force, the most important cardiac performance parameter, served as an integrated outcome measure. EHTs from neonatal rat cardiomyocytes were subjected to 90 min of hypoxia which led to cardiomyocyte apoptosis as revealed by caspase 3-staining, increased troponin I release (time control vs. 24 h after hypoxia: cTnI 2.7 vs. 6.3 ng/mL, ** p = 0.002) and decreased contractile force (64 ± 6% of baseline) in the long-term follow-up. The detrimental effects were attenuated by preceding the long-term hypoxia with three cycles of 10 min hypoxia (i.e., hypoxic preconditioning). Similarly, [d-Ala2, d-Leu5]-enkephalin (DADLE) reduced the effect of hypoxia on force (recovery to 78 ± 5% of baseline with DADLE preconditioning vs. 57 ± 5% without, p = 0.012), apoptosis and cardiomyocyte stress. Human EHTs presented a comparable hypoxia-induced reduction in force (55 ± 5% of baseline), but DADLE failed to precondition them, likely due to the absence of δ-opioid receptors. In summary, this hypoxia-reoxygenation in vitro model displays cellular damage and the decline of contractile function after hypoxia allows the investigation of preconditioning strategies and will therefore help us to understand the discrepancy between successful conditioning in vitro experiments and its failure in clinical trials.

Preconditioning in cardiac anesthesia…… where are we?

Preconditioning, a milestone concept in the cardiovascular sciences introduced 32 years back by Murry. This concept opened a new era in the field of organ protection. To start with extensive studies done on ischemic preconditioning for myocardial protection, ischemic preconditioning is an endogenous science of cellular kinetics. Several components in signal transduction cascade have been identified but still some mechanisms not yet revealed. Anesthetic preconditioning also contributed a lot for myocardial protection and concreted the concept of preconditioning. We, with an inquisitive brain meticulously persuing newer methods of cardioprotection. Remote ischemic preconditioning (RIPC) is a brilliant example of it. RIPC can be future of cardioprotection, clinical trials and studies proved the benefits but yet to conclude the superiority of RIPC over myocardial ischemic cardioprotection. This review is an attempt to reveal this extraordinary concept with its basic cellular kinetics, methods, and recent trends.

Remifentanil preconditioning protects against hypoxia-induced senescence and necroptosis in human cardiac myocytes in vitro

Remifentanil and other opioids are suggested to be protective against ischemia-reperfusion injury in animal models and coronary artery bypass surgery patients, however the molecular basis of such protection is far from being understood. In the present study, we have used a model of human cardiomyocytes treated with the hypoxia-mimetic agent cobalt chloride to investigate remifentanil preconditioning-based adaptive responses and underlying mechanisms. Hypoxic conditions promoted oxidative and nitrosative stress, p21-mediated cellular senescence and the activation of necroptotic pathway that was accompanied by a 2.2-, 9.6- and 8.2-fold increase in phosphorylation status of mixed lineage kinase domain-like pseudokinase (MLKL) and release of pro-inflammatory cytokine IL-8 and cardiac troponin I, a marker of myocardial damage, respectively. Remifentanil preconditioning was able to lower hypoxia-mediated protein carbonylation and limit MLKL-based signaling and pro-inflammatory response to almost normoxic control levels, and decrease hypoxia-induced pro-senescent activity of about 21% compared to control hypoxic conditions. In summary, we have shown for the first time that remifentanil can protect human cardiomyocytes against hypoxia-induced cellular senescence and necroptosis that may have importance with respect to the use of remifentanil to diminish myocardial ischemia and reperfusion injury in patients undergoing cardiac surgery.

Agonist-induced phosphorylation bar code and differential post-activation signaling of the delta opioid receptor revealed by phosphosite-specific antibodies

The δ-opioid receptor (DOP) is an attractive pharmacological target due to its potent analgesic, anxiolytic and anti-depressant activity in chronic pain models. However, some but not all selective DOP agonists also produce severe adverse effects such as seizures. Thus, the development of novel agonists requires a profound understanding of their effects on DOP phosphorylation, post-activation signaling and dephosphorylation. Here we show that agonist-induced DOP phosphorylation at threonine 361 (T361) and serine 363 (S363) proceeds with a temporal hierarchy, with S363 as primary site of phosphorylation. This phosphorylation is mediated by G protein-coupled receptor kinases 2 and 3 (GRK2/3) followed by DOP endocytosis and desensitization. DOP dephosphorylation occurs within minutes and is predominantly mediated by protein phosphatases (PP) 1α and 1β. A comparison of structurally diverse DOP agonists and clinically used opioids demonstrated high correlation between G protein-dependent signaling efficacies and receptor internalization. In vivo, DOP agonists induce receptor phosphorylation in a dose-dependent and agonist-selective manner that could be blocked by naltrexone in DOP-eGFP mice. Together, our studies provide novel tools and insights for ligand-activated DOP signaling in vitro and in vivo and suggest that DOP agonist efficacies may determine receptor post-activation signaling.

Mechanisms Involved in Cardioprotection Induced by Physical Exercise

Significance: Regular exercise training can reduce myocardial damage caused by acute ischemia/reperfusion (I/R). Exercise can reproduce the phenomenon of ischemic preconditioning, due to the capacity of brief periods of ischemia to reduce myocardial damage caused by acute I/R. In addition, exercise may also activate the multiple kinase cascade responsible for cardioprotection even in the absence of ischemia. Recent Advances: Animal and human studies highlighted the fact that, besides to reduce risk factors related to cardiovascular disease, the beneficial effects of exercise are also due to its ability to induce conditioning of the heart. Exercise behaves as a physiological stress that triggers beneficial adaptive cellular responses, inducing a protective phenotype in the heart. The factors contributing to the exercise-induced heart preconditioning include stimulation of the anti-radical defense system and nitric oxide production, opioids, myokines, and adenosine-5'-triphosphate (ATP) dependent potassium channels. They appear to be also involved in the protective effect exerted by exercise against cardiotoxicity related to chemotherapy. Critical Issues and Future Directions: Although several experimental evidences on the protective effect of exercise have been obtained, the mechanisms underlying this phenomenon have not yet been fully clarified. Further studies are warranted to define precise exercise prescriptions in patients at risk of myocardial infarction or undergoing chemotherapy.

LncRNA 1700020I14Rik/miR-297a/CGRP axis suppresses myocardial cell apoptosis in myocardial ischemia-reperfusion injury

BACKGROUND

Long non-coding RNAs (lncRNAs) are closely related to various human diseases, but their role in myocardial injury has not been fully elucidated. In the current study, we found that the expression of lncRNA 1700020I14Rik was significantly down-regulated in myocardial injury tissues and the underlying mechanism by which lncRNA 1700020I14Rik regulated myocardial cell injury was investigated.

METHODS

The model of myocardial ischemia-reperfusion (I/R) injury and myocardial cells hypoxia/reoxygenation (H/R) injury were established and the expression of 1700020I14Rik, miR-297a or CGRP was analyzed by qRT-PCR or Western blot. Moreover, myocardial cell apoptosis was assessed by TUNEL staining and the concentration of LDH in the mouse plasma sample or myocardial cell culture supernatant was measured by the LDH cytotoxicity test kit. Furthermore, the differences of myocardial cell survival rate after H/R treatment were assessed by MTT assay and the observation of CGRP expression was performed in HL-1 cells overexpressed or silenced with 1700020I14Rik or miR-297a. In addition, the regulating function of miR-297a on 1700020I14Rik and CGRP expression was analyzed by a dual luciferase reporter assay.

RESULTS

The expressions of 1700020I14Rik and CGRP were abnormally down-regulated in a model of myocardial I/R injury and myocardial cells H/R injury, while miR-297a was up-regulated. By TUNEL staining, the apoptotic rate of myocardial cells in the model of myocardial I/R injury was significantly increased. Furthermore, the concentrations of LDH in the mouse plasma sample or myocardial cell culture supernatant were significantly increased after myocardial cell injury. By MTT assay, the survival rate of cells was decreased after myocardial cells were treated with H/R. In addition, overexpression of 1700020I14Rik or knockdown of miR-297a could up-regulate CGRP protein level, while interference with 1700020I14Rik or overexpression of miR-297a produced the opposite result. Further study confirmed that lncRNA 1700020I14Rik/miR-297a/CGRP axis suppressed myocardial cell apoptosis in myocardial I/R injury.

CONCLUSION

Our results indicated that 1700020I14Rik was abnormally down-regulated in myocardial injury tissues. In-depth studies manifested that 1700020I14Rik/miR-297a/CGRP axis suppressed myocardial cell apoptosis in myocardial I/R injury.

κ-opioid receptor activation promotes mitochondrial fusion and enhances myocardial resistance to ischemia and reperfusion injury via STAT3-OPA1 pathway

Mitochondrial dynamics, determining mitochondrial morphology, quality and abundance, have recently been implicated in myocardial ischemia and reperfusion (MI/R) injury. The roles of κ-opioid receptor activation in cardioprotection have been confirmed in our previous studies, while the underlying mechanism associated with mitochondrial dynamics remains unclear. This study aims to investigate the effect of κ-opioid receptor activation on the pathogenesis of MI/R and its underlying mechanisms. MI/R mouse model and hypoxia-reoxygenation cardiomyocyte model were established in this study. Mitochondrial dynamics were analyzed with transmission electron microscopy in vivo and confocal microscopy in vitro. STAT3 phosphorylation and OPA1 expression were detected by Western blotting. We show here that κ-opioid receptor activation with its selective receptor agonist U50,488H promoted mitochondrial fusion and enhanced myocardial resistance to MI/R injury, while these protective effects were blockaded by nor-BNI, a selective κ-opioid receptor antagonist. In addition, κ-opioid receptor activation increased STAT3 phosphorylation and OPA1 expression, which were blockaded by nor-BNI. Furthermore, inhibition of STAT3 phosphorylation by stattic, a specific STAT3 inhibitor, repressed the effects of κ-opioid receptor activation on promoting OPA1 expression and mitochondrial fusion, as well as inhibiting cell apoptosis and oxidative stress both in vivo and in vitro during MI/R injury. Overall, our data for the first time provide evidence that κ-opioid receptor activation promotes mitochondrial fusion and enhances myocardial resistance to MI/R injury via STAT3-OPA1 pathway. Targeting the pathway regulated by κ-opioid receptor activation may be a potential therapeutic strategy for MI/R injury.