Effects of trimetazidine, a partial inhibitor of fatty acid oxidation, on ventricular function and survival after myocardial infarction and reperfusion in the rat

Regulatory effects of trimetazidine in cardiac ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a tissue damage during reperfusion after an ischemic condition. I/R injury is induced by pathological cases including stroke, myocardial infarction, circulatory arrest, sickle cell disease, acute kidney injury, trauma, and sleep apnea. It can lead to increased morbidity and mortality in the context of these processes. Mitochondrial dysfunction is one of the hallmarks of I/R insult, which is induced via reactive oxygen species (ROS) production, apoptosis, and autophagy. MicroRNAs (miRNAs, miRs) are non-coding RNAs that play a main regulatory role in gene expression. Recently, there are evidence, which miRNAs are the major modulators of cardiovascular diseases, especially myocardial I/R injury. Cardiovascular miRNAs, specifically miR-21, and probably miR-24 and miR-126 have protective effects on myocardial I/R injury. Trimetazidine (TMZ) is a new class of metabolic agents with an anti-ischemic activity. It has beneficial effects on chronic stable angina by suppressing mitochondrial permeability transition pore (mPTP) opening. The present review study addressed the different mechanistic effects of TMZ on cardiac I/R injury. Online databases including Scopus, PubMed, Web of Science, and Cochrane library were assessed for published studies between 1986 and 2021. TMZ, an antioxidant and metabolic agent, prevents the cardiac reperfusion injury by regulating AMP-activated protein kinase (AMPK), cystathionine-γ-lyase enzyme (CSE)/hydrogen sulfide (H2S), and miR-21. Therefore, TMZ protects the heart against I/R injury by inducing key regulators such as AMPK, CSE/H2S, and miR-21.

Trimetazidine alleviates hypoxia/reoxygenation-induced apoptosis in neonatal mice cardiomyocytes via up-regulating HMGB1 expression to promote autophagy

Previous studies demonstrated the effect of Trimetazidine (TMZ) on alleviating cardiomyocytes Hypoxia/Reoxygenation (H/R) injuries and the protective effect of autophagy on Ischemia-Reperfusion (I/R) cell injuries. However, whether the protection mechanism of TMZ was also involved in autophagy remained unclear. Our study introduces the role of HMGB1 to examine the regulation of TMZ on autophagy against cardiomyocytes H/R injuries. After cell extraction and identification through anti-α-actin staining, the cardiomyocytes were made hypoxic and reoxygenated, each for 3 h, and then treated with various concentrations of TMZ and transfected with siHMGB1. Cell viability and apoptosis were measured by the MTS method and flow cytometry, respectively. The expressions of autophagy-related factors (LC3-I, LC3-II, Beclin-1) and HMGB1 were detected by Western blot and qPCR. Lactate dehydrogenase (LDH) release was assessed by ELISA kit. The cardiomyocytes were extracted. H/R decreased the cell viability and increased the LDH level and apoptosis of cardiomyocytes. TMZ had no effect on untreated cardiomyocytes, but it reversed the adverse impact of H/R on cardiomyocytes. The expressions of LC3-II, Beclin-1, and HMGB1 and the ratio of LC3-II/LC3-I were increased in H/R-processed cardiomyocytes and further raised by TMZ pretreatment. However, siHMGB1 transfection aggravated the impact of H/R on cardiomyocytes and suppressed the protective effects of TMZ on H/R damaged cardiomyocytes by increasing the LDH level and apoptosis and reducing the viability of cardiomyocytes. Autophagy was inhibited by siHMGB1 in TMZ-pretreated and H/R-processed cardiomyocytes. TMZ protected cardiomyocytes against H/R injuries may through regulating HMGB1 to increase the impact of autophagy.

Trimetazidine Protects Cardiomyocytes Against Hypoxia/Reoxygenation Injury by Promoting AMP-activated Protein Kinase-dependent Autophagic Flux

Trimetazidine (TMZ), a metabolic agent, may protect against myocardial ischemia/reperfusion injury. Because of the critical role of autophagy in cardioprotection, we aimed to evaluate whether autophagy was involved in TMZ-induced protection during hypoxia/reoxygenation (H/R). Neonatal rat cardiomyocytes were subjected to H/R injury, and they were divided into 7 groups: control, control+TMZ, control+chloroquine (Cq)/compound C (com C), H/R, H/R+TMZ, H/R+Cq/com C, and H/R+TMZ+Cq/com C. Autophagic flux was primarily assessed by Western blot and tandem fluorescent mRFP-GFP-LC3. Assays for MTS, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, and lactate dehydrogenase release were performed to assess cell injury. Our results showed that TMZ pretreatment had a cardioprotective effect against H/R injury. The H/R+TMZ group had an increased ratio of LC3-II to LC3-I and increased autophagic flux (degradation of p62 and increases in autophagosomes and autolysosomes). TMZ also reduced apoptosis and enhanced cell survival while inducing autophagy. Correspondingly, autophagy inhibition with Cq blocked this protective effect. Furthermore, TMZ-induced enhancement of autophagy could be related to increased AMP-activated protein kinase (AMPK) phosphorylation and decreased Mammalian target of rapamycin (mTOR) phosphorylation, which was abolished by an AMPK-specific inhibitor (com C). Our data provide evidence that TMZ pretreatment protects against H/R injury by promoting autophagic flux through the AMPK signaling pathway.

Effect of Ginkgo biloba extract on experimental cardiac remodeling

Background

To investigate the ameliorated effects of an extract of Ginkgo biloba extract (GBE) on experimental cardiac remodeling in rats induced by acute cardiac infarction, and further explore the mechanism concentrated on myocardial type I collagen, transforming growth factor beta 1 (TGF-β1), matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9), and provide the experimentaldata for clinical application of GBE.

Methods

Rats were divided into five groups (n = 20) as following: sham operation group (group A), acute myocardial infarction model group (group B), acute myocardial infarction model + aspirin (10 mg/kg) treatment group (group C), acute myocardial infarction model + captopril (20 mg/kg) treatment group (group D) and acute myocardial infarction model + Ginkgo biloba extract (100 mg/kg) treatment group (group E). The rat acute myocardial infarction model was reproduced by ligaturing the left anterior descending artery excluding the sham operation group which did not ligation only completed the operational process. Each group was further subdivided into treatment regimens lasting 4 weeks and 8 weeks. Immunohistochemistry and real-time polymerase chain reaction (PCR) methods were used to detect the protein expression and mRNA transcriptional levels of rat myocardial TGF-β1, type I collagen, MMP-2 and MMP-9.

Results

Compared with group B, regardless of the length of treatment (4 or 8 weeks), the TGF-β1, MMP-2 and MMP-9 mRNA transcriptional levels, and the protein expression levels of type I collagen, MMP-2 and MMP-9 in groups D, C and E were significantly decreased (P < 0.01). Furthermore, the mRNA expression levels of TGF-β1 in groups D, C and E were significantly lower after 8 weeks compared to after 4 weeks (P < 0.01), as were the expression levels of type I collagen in groups D, C and E (P < 0.05). There was no statistically significant difference in the protein expression levels of MMP-2 and MMP-9 between groups E and C.

Conclusions

GBE could inhibit experimental rat myocardial remodeling after acute myocardial infarction via reduced transcription of TGF-β1, MMP-2 and MMP-9 genes and by the decreased expression of type I collagen, MMP-2 and MMP-9 proteins in myocardial cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-015-0719-z) contains supplementary material, which is available to authorized users.

Myocardial substrate metabolism in obesity

Obesity is linked to a wide variety of cardiac changes, from subclinical diastolic dysfunction to end-stage systolic heart failure. Obesity causes changes in cardiac metabolism, which make ATP production and utilization less efficient, producing functional consequences that are linked to the increased rate of heart failure in this population. As a result of the increases in circulating fatty acids and insulin resistance that accompanies excess fat storage, several of the proteins and genes that are responsible for fatty acid uptake and metabolism are upregulated, and the metabolic machinery responsible for glucose utilization and oxidation are inhibited. The resultant increase in fatty acid metabolism, and the inherent alterations in the proteins of the electron transport chain used to create the gradient needed to drive mitochondrial ATP production, results in a decrease in efficiency of cardiac work and a relative increase in oxygen usage. These changes in cardiac mitochondrial metabolism are potential therapeutic targets for the treatment and prevention of obesity-related heart failure.

Diabetes, perioperative ischaemia and volatile anaesthetics: consequences of derangements in myocardial substrate metabolism

Volatile anaesthetics exert protective effects on the heart against perioperative ischaemic injury. However, there is growing evidence that these cardioprotective properties are reduced in case of type 2 diabetes mellitus. A strong predictor of postoperative cardiac function is myocardial substrate metabolism. In the type 2 diabetic heart, substrate metabolism is shifted from glucose utilisation to fatty acid oxidation, resulting in metabolic inflexibility and cardiac dysfunction. The ischaemic heart also loses its metabolic flexibility and can switch to glucose or fatty acid oxidation as its preferential state, which may deteriorate cardiac function even further in case of type 2 diabetes mellitus.Recent experimental studies suggest that the cardioprotective properties of volatile anaesthetics partly rely on changing myocardial substrate metabolism. Interventions that target at restoration of metabolic derangements, like lifestyle and pharmacological interventions, may therefore be an interesting candidate to reduce perioperative complications. This review will focus on the current knowledge regarding myocardial substrate metabolism during volatile anaesthesia in the obese and type 2 diabetic heart during perioperative ischaemia.

Mitochondria as a drug target in ischemic heart disease and cardiomyopathy

Ischemic heart disease is a significant cause of morbidity and mortality in Western society. Although interventions, such as thrombolysis and percutaneous coronary intervention, have proven efficacious in ischemia and reperfusion injury, the underlying pathological process of ischemic heart disease, laboratory studies suggest further protection is possible, and an expansive research effort is aimed at bringing new therapeutic options to the clinic. Mitochondrial dysfunction plays a key role in the pathogenesis of ischemia and reperfusion injury and cardiomyopathy. However, despite promising mitochondria-targeted drugs emerging from the laboratory, very few have successfully completed clinical trials. As such, the mitochondrion is a potential untapped target for new ischemic heart disease and cardiomyopathy therapies. Notably, there are a number of overlapping therapies for both these diseases, and as such novel therapeutic options for one condition may find use in the other. This review summarizes efforts to date in targeting mitochondria for ischemic heart disease and cardiomyopathy therapy and outlines emerging drug targets in this field.

Modulating fatty acid oxidation in heart failure

In the advanced stages of heart failure, many key enzymes involved in myocardial energy substrate metabolism display various degrees of down-regulation. The net effect of the altered metabolic phenotype consists of reduced cardiac fatty oxidation, increased glycolysis and glucose oxidation, and rigidity of the metabolic response to changes in workload. Is this metabolic shift an adaptive mechanism that protects the heart or a maladaptive process that accelerates structural and functional derangement? The question remains open; however, the metabolic remodelling of the failing heart has induced a number of investigators to test the hypothesis that pharmacological modulation of myocardial substrate utilization might prove therapeutically advantageous. The present review addresses the effects of indirect and direct modulators of fatty acid (FA) oxidation, which are the best pharmacological agents available to date for 'metabolic therapy' of failing hearts. Evidence for the efficacy of therapeutic strategies based on modulators of FA metabolism is mixed, pointing to the possibility that the molecular/biochemical alterations induced by these pharmacological agents are more complex than originally thought. Much remains to be understood; however, the beneficial effects of molecules such as perhexiline and trimetazidine in small clinical trials indicate that this promising therapeutic strategy is worthy of further pursuit.