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AICAR-cardioprotection in doxorubicin-induced heart failure in rats

ABSTRACT: Doxorubicin (DOX) is a widely used chemotherapeutic agent that can cause serious cardiotoxic side effects, leading to functional cardiac decline and ultimately, congestive heart failure (HF). Impaired mitochondrial function and energetics are thought to be key factors driving progression into HF. We have previously shown in a rat model of chronic intravenous DOX-administration that heart failure with reduced ejection fraction correlates with mitochondrial loss and dysfunction. Adenosine monophosphate-dependent kinase (AMPK) is a cellular energy sensor, regulating mitochondrial biogenesis and oxidative metabolism, including fatty acid oxidation. We hypothesized that AMPK activation could restore mitochondrial number and function and therefore be a novel cardioprotective strategy for the prevention of DOX-HF. Consequently, we set out to assess whether 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR), an activator of AMPK, could prevent cardiac functional decline in this clinically relevant rat model of DOX-HF. In line with our hypothesis, AICAR improved cardiac systolic function. This was associated with normalisation of substrate supply to the heart, as AICAR prevented DOX-induced dyslipidaemia. AICAR furthermore improved cardiac mitochondrial fatty acid oxidation, independent of mitochondrial number. In addition, we found that AICAR reduced the degree of myocardial atrophy, and RNAseq analysis showed that this was driven by normalisation of protein synthesis pathways, which are impaired in DOX-treated rat hearts. Taken together, these results show promise for the use of AICAR as a cardioprotective agent in DOX-HF to both preserve cardiac function and mass.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE218397 | GEO | 2024/11/01

REPOSITORIES: GEO

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Project description:OBJECTIVE: To explore the cardioprotective effects of exercise-derived β-aminoisobutyric (BAIBA) on cardiomyocyte apoptosis and energy metabolism in a rat model of heart failure (HF).METHODS: In male Sprague-Dawley rats (8-week-old), myocardial infarction (MI) was used to induce HF by ligating the left anterior descending branch of the coronary artery. In the Sham group, the coronary artery was threaded but not ligated. After HF development, Sham and HF rats were exercised 60 min daily, 5 days per week on a treadmill for 8 weeks (50-60% maximal intensity) and exercise-induced cardiac remodeling after MI were assessed using echocardiography, hematoxylin and eosin (H&E), Masson’s Trichrome and TUNEL staining for the detection of apoptosis-associated factors in cardiac tissue. High-throughput sequencing and mass spectrometry were used to measure BAIBA production and to explore its cardioprotective effects and molecular actions. To further characterize the cardioprotective effects of BAIBA, an in vitro model of apoptosis was generated by applying H2O2 to H9C2 cells to induce mitochondrial dysfunction. In addition, cells were transfected with either a miR-208b analogue or a miR-208b inhibitor. Apoptosis-related proteins were detected by Western Blotting (WB). ATP production was also assessed by luminometry. After administration of BAIBA and Compound C, the expression of proteins related to apoptosis, mitochondrial function, lipid uptake and β-oxidative were determined. Changes in the levels of reactive oxygen species (ROS) were assessed by fluorescence microscopy. In addition, alterations in membrane potential (δψm) were obtained by confocal microscopy.RESULTS: Rats with HF after MI are accompanied by mitochondrial dysfunction, metabolic stress and apoptosis. Reduced expression of apoptosis-related proteins was observed, together with increased ATP production and reduced mitochondrial dysfunction in the exercised compared with the Sham (non-exercised) HF group. Importantly, exercise increased the production of BAIBA, irrespective of the presence of HF. To assess whether BAIBA had similar effects to exercise in ameliorating HF-induced adverse cardiac remodeling, rats were treated with 75 mg/kg/day of BAIBA and we found BAIBA had a similar cardioprotective effect. Transcriptomic analyses found that the expression of miR-208b was increased after BAIBA administration, and subsequent transfection with an miR-208b analogue ameliorated both the expression of apoptosis-related proteins and energy metabolism in H2O2-treated H9C2 cells. In combining transcriptomic with metabolomic analyses, we identified AMPK as a downstream target for BAIBA in attenuating metabolic stress in HF. Further cell experiments confirmed that BAIBA increased AMPK phosphorylation and had a cardioprotective effect on downstream fatty acid uptake, oxidative efficiency and mitochondrial function, which was prevented by the AMPK inhibitor Compound C.CONCLUSION: Exercise-generated BAIBA can reduce cardiomyocyte metabolic stress and apoptosis induced by mitochondrial dysfunction through the miR-208b/AMPK pathway.

Project description:Objective: To explore the protective effects of exercise-derived β-aminoisobutyric (BAIBA) on apoptosis and energy metabolism in rats with heart failure. Methods: A rat model of heart failure after myocardial infarction (MI) was started by ligating the left anterior descending branch of the coronary artery, the anterior descending branch of the rats in the SHAM group was only threaded and not ligated. Exercise intervention was given to rats with heart failure. The possible mechanisms by which exercise affected cardiac remodeling after MI were investigated using color ultrasound, HE, Masson, and TUNEL staining, and the detection of apoptosis-associated factors in cardiac tissue. High-throughput sequencing and mass spectrometry were used to measure the production of BAIBA and to explore its protective effects and molecular mechanisms. An in vitro model of apoptosis was created by the application of H2O2 to induce mitochondrial dysfunction. This was then transfected with miR-208b analogue and miR-208b-inhibitor. Apoptosis-related proteins were detected by Western blotting (WB), and ATP production was also assessed. After intervention with BAIBA and compound C, assessments were made of apoptosis, mitochondrial function, lipid uptake, utilization of related proteins, ATP changes, alterations in membrane potential (δψm), and changes in reactive oxygen species (ROS). Results: Compared with the control heart failure (HF) group, exercise improved the function of mitochondria, reversed the expression of apoptosis-related proteins, and increased ATP production. In both the normal and heart failure groups, exercise significantly increased the production of BAIBA. It was shown that BAIBA played a similar role to exercise in ameliorating heart failure. Transcriptome analysis confirmed that the expression of miR-208b was increased after BAIBA intervention, and transfection with miR-208b analogue increased both the expression of apoptosis-related proteins and energy metabolism in H9C2 cells induced by H2O2. Combined analysis of the transcriptome and metabolome identified AMPK as a target for BAIBA to improve metabolic stress. Cell experiments further confirmed that BAIBA increased AMPK phosphorylation and had a protective effect on downstream fatty acid uptake, oxidative efficiency, and mitochondrial function, which could be counteracted by the AMPK inhibitor compound C. Conclusion: Exercise-induced BAIBA can reduce the metabolic stress and apoptosis induced by mitochondrial dysfunction through the miR-208b/AMPK pathway.

Project description:Compelling evidence suggests that mitochondrial dysfunction contributes to the pathogenesis of heart failure, including defects in the substrate oxidation, and the electron transport chain (ETC) and oxidative phosphorylation (OXPHOS). However, whether such changes occur early in the development of heart failure, and are potentially involved in the pathologic events that lead to cardiac dysfunction is unknown. To address this question, we conducted transcriptomic/metabolomics profiling in hearts of mice with two progressive stages of pressure overload-induced cardiac hypetrophy: i) cardiac hypertrophy with preserved ventricular function achieved via transverse aortic constriction for 4 weeks (TAC) and ii) decompensated cardiac hypertrophy or heart failure (HF) caused by combining 4 wk TAC with a small apical myocardial infarction. Transcriptomic analyses revealed, as shown previously, downregulated expression of genes involved in mitochondrial fatty acid oxidation in both TAC and HF hearts compared to sham-operated control hearts. Surprisingly, however, there were very few changes in expression of genes involved in other mitochondrial energy transduction pathways, ETC, or OXPHOS. Metabolomic analyses demonstrated significant alterations in pathway metabolite levels in HF (but not in TAC), including elevations in acylcarnitines, a subset of amino acids, and the lactate/pyruvate ratio. In contrast, the majority of organic acids were lower than controls. This metabolite profile suggests “bottlenecks” in the carbon substrate input to the TCA cycle. This transcriptomic/metabolomic profile was markedly different from that of mice PGC-1a/b deficiency in which a global downregulation of genes involved in mitochondrial ETC and OXPHOS was noted. In addition, the transcriptomic/metabolomic signatures of HF differed markedly from that of the exercise-trained mouse heart. We conclude that in contrast to current dogma, alterations in mitochondrial metabolism that occur early in the development of heart failure reflect largely post-transcriptional mechanisms resulting in impedance to substrate flux into the TCA cycle, reflected by alterations in the metabolome. Microarray gene expression profiling was performed with bi-ventricle RNA isolated from (1) 3 month-old female C57Bl6/J mice with transverse aortic constriction (CH), vs sham-operated control (Sham-CH), (2) 3 month-old female C57Bl6/J mice with heart failure (HF), vs. sham-operated control (Sham-HF); (3) 2 month-old female C57Bl6/J mice with voluntary wheel training for 2 months (Run), vs. Sedentary control (Sed). Five biological replicates are included for each group.

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AICAR-cardioprotection in doxorubicin-induced heart failure in rats

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