Mitochondrial Respiratory Control Research Articles

Captivity affects mitochondrial aerobic respiration and carotenoid metabolism in the house finch (Haemorhous mexicanus).

In many species of animals, red carotenoid-based coloration is produced by metabolizing yellow dietary pigments, and this red ornamentation can be an honest signal of individual quality. However, the physiological basis for associations between organism function and the metabolism of red ornamental carotenoids from yellow dietary carotenoids remains uncertain. A recent hypothesis posits that carotenoid metabolism depends on mitochondrial performance, with diminished red coloration resulting from altered mitochondrial aerobic respiration. To test for an association between mitochondrial respiration and red carotenoids, we held wild-caught, molting male house finches in either small bird cages or large flight cages to create environmental challenges during the period when red ornamental coloration is produced. We predicted that small cages would present a less favorable environment than large flight cages and that captivity itself would decrease both mitochondrial performance and the abundance of red carotenoids compared with free-living birds. We found that captive-held birds circulated fewer red carotenoids, showed increased mitochondrial respiratory rates, and had lower complex II respiratory control ratios - a metric associated with mitochondrial efficiency - compared with free-living birds, though we did not detect a difference in the effects of small cages versus large cages. Among captive individuals, the birds that circulated the highest concentrations of red carotenoids had the highest mitochondrial respiratory control ratio for complex II substrate. These data support the hypothesis that the metabolism of red carotenoid pigments is linked to mitochondrial aerobic respiration in the house finch, but the mechanisms for this association remain to be established.

Hepatic Runx1t1 improves body fat index after endurance exercise in obese mice

Endurance exercise could attenuate obesity induced by high fat diet (HFD). Thus, the purpose of this study was to explore the crucial targets that play key roles in the improvement of body fat index (BFI) in obese mice by endurance exercise. Firstly, we constructed murine obesity models: High fat diet control (HFD) group, HFD exercise (HFE) group, normal chow diet control (NC) group, and normal chow diet exercise (NE) group. Next, we identified the BFI improvement related genes using differential gene analysis, and investigated these genes’ functional pathways using functional enrichment analysis. The qRT-PCR and western blot assays were used to determine the gene expression and protein expression, respectively. Gene set enrichment analysis was used to explore the potential pathways associated with endurance exercise in obese mice and Mitochondrial respiratory control ratio (RCR) assay was applied to determine the RCR in the liver tissues of mice. We discovered that endurance exercise remarkably reduced the body weights and BFI of HFD-induced obese mice. Runx1t1 was related to the improvement of BFI by endurance exercise in HFD-induced obese mice. Runx1t1 mRNA and protein levels in liver tissues were observably decreased in HFD mice compared to mice in HFE, NC and NE groups. Moreover, Glucagon signaling pathway that was associated with mitochondrial function was significantly activated in HFE mice. The Runx1t1 expression exhibited an observable negative correlation with Acaca in HFD mice. Moreover, the mitochondrial RCR level was significantly increased in HFE mice than that in HFD mice. In HFD-induced obese mice, Runx1t1 was implicated in the improvement of BFI via endurance exercise. Endurance exercise could improve mitochondrial dysfunction in obese mice by activating the Runx1t1.

A practical perspective on how to develop, implement, execute, and reproduce high-resolution respirometry experiments: The physiologist's guide to an Oroboros O2k.

The development of high-resolution respirometry (HRR) has greatly expanded the analytical scope to study mitochondrial respiratory control relative to specific tissue/cell types across various metabolic states. Specifically, the Oroboros Oxygraph 2000 (O2k) is a common tool for measuring rates of mitochondrial respiration and is the focus of this perspective. The O2k platform is amenable for answering numerous bioenergetic questions. However, inherent variability with HRR-derived data, both within and amongst users, can impede progress in bioenergetics research. Therefore, we advocate for several vital considerations when planning and conducting O2k experiments to ultimately enhance transparency and reproducibility across laboratories. In this perspective, we offer guidance for best practices of mitochondrial preparation, protocol selection, and measures to increase reproducibility. The goal of this perspective is to propagate the use of the O2k, enhance reliability and validity for both new and experienced O2k users, and provide a reference for peer reviewers.

Aldehyde Dehydrogenase 2 Preserves Mitochondrial Function in the Ischemic Heart: A Redox-dependent Mechanism for AMPK Activation by Thioredoxin-1.

Aldehyde dehydrogenase 2 (ALDH2) protects the ischemic heart by activating adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling. However, the molecular mechanisms linking ALDH2 and AMPK signaling are not fully understood. This study aimed to explore the potential mechanisms linking ALDH2 and AMPK in myocardial ischemic injury. An ischemic model was established by ligating the left anterior descending coronary artery in rats. The overexpression or knockdown of ALDH2 in H9c2 cells treated with oxygen-glucose deprivation was obtained through lentivirus infection. Transferase-mediated dUTP nick-end labeling was used to evaluate apoptosis in an ischemic rat model and oxygen-glucose deprivation cells. ALDH2 activity, mitochondrial oxidative stress markers, adenosine triphosphate, respiratory control ratio, and cell viability in H9c2 cells were evaluated using a biological kit and 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide. Protein expression of ALDH2 , 4-hydroxynonenal, thioredoxin-1 (Trx-1), and AMPK-proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) signaling pathway was detected through Western blotting. ALDH2 activation reduced ischemic-induced myocardial infarct size and apoptosis. ALDH2 protected mitochondrial function by enhancing mitochondrial respiratory control ratio and adenosine triphosphate production, alleviated mitochondrial oxidative stress, and suppressed myocardial apoptosis. Moreover, ALDH2 attenuated ischemia-induced oxidative stress and maintained Trx-1 levels by reducing 4-hydroxynonenal, thereby promoting AMPK-PGC-1α signaling activation. Inhibiting Trx-1 or AMPK abolished the cardioprotective effect of ALDH2 on ischemia. ALDH2 alleviates myocardial injury through increased mitochondrial biogenesis and reduced oxidative stress, and these effects were achieved through Trx1-mediating AMPK-PGC1-α signaling activation.

Dietary apple polyphenols enhance mitochondrial turnover and respiratory chain enzymes.

Previous studies have demonstrated the beneficial effects of apple polyphenol (AP) intake on muscle endurance. Since mitochondria are critical for muscle endurance, we investigated mitochondrial enzyme activity, biogenesis, degradation and protein quality control. Twenty-four Wistar rats were randomly fed a 5% AP diet (5% AP group, n=8), a 0.5% AP diet (0.5% AP group, n=8), or a control diet (control group, n=8). After a 4-week feeding period, the expression level of peroxisome proliferator-activated receptor γ coactivator-1α, a mitochondrial biosynthetic factor, did not increase, whereas that of transcription factor EB, another regulator of mitochondrial synthesis, significantly increased. Moreover, the mitochondrial count did not differ significantly between the groups. In contrast, mitophagy-related protein levels were significantly increased. The enzymatic activities of mitochondrial respiratory chain complexes II, III and IV were significantly higher in the AP intake group than in the control group. We conclude that AP feeding increases the activity of respiratory chain complex enzymes in rat skeletal muscles. Moreover, mitochondrial biosynthesis and degradation may have increased in AP-treated rats. NEW FINDINGS: What is the central question of this study? Does the administration of apple polyphenols (AP) affect mitochondrial respiratory chain complex enzyme activity, biogenesis, degradation and protein quality control in rat skeletal muscles? What is the main finding and its importance? AP feeding increases respiratory chain complex enzyme activity in rat skeletal muscle. Moreover, AP administration increases transcription factor EB activation, and mitophagy may be enhanced to promote degradation of dysfunctional mitochondria, but mitochondrial protein quality control was not affected.

Cardiomyocyte mitochondrial respiration and microviscosity in rats of different ages in heart failure

Highlights. Heart failure in older age groups is an urgent medical and social issue. Mitochondrial dysfunction is a key link in the pathogenesis of heart failure. In this study we have demonstrated a decrease in mitochondrial respiratory function in old rats. In this age group, the development of heart failure is accompanied by a further decrease in respiratory control. An increase in the mitochondrial microviscosity in older animals may affect the activity of respiratory chain enzymes in heart failure.Aim. To study the respiratory activity and mitochondrial membrane microviscosity of cardiomyocyte of rats of different ages with heart failure.Methods. The study involved 22 2- and 15-month-old male Wistar rats. The animals were divided into 4 groups: 2 groups of intact animals of both ages (n = 12) and 2 groups of rats with isadrine model of heart failure (HF) (n = 10). HF was modeled by two subcutaneous injections of isoproterenol hydrochloride (170 mg/kg) at interval of 24 hours. Mitochondrial respiratory activity was assessed using respiratory control coefficient. The microviscosity of mitochondrial membranes was evaluated by eximerization coefficients of pyrene-based fluorescent probe in areas of protein-lipid and lipid-lipid contact. Comparative statistical analysis of independent groups was performed using the nonparametric Mann-Whitney test.Results. A decrease in mitochondrial respiratory control in older rats was shown in comparison with young animals. In the HF model, inter-age difference increases, but at the same time, in younger rats, the development of HF is not accompanied by significant changes in mitochondrial respiratory control. An age dependent decrease in the microviscosity of mitochondrial membranes in the area of protein-lipid and lipid-lipid interaction was revealed. In younger rats, the development of HF is characterized by a significant increase in microviscosity in the area of protein-lipid and lipid-lipid contact. In older rats, the development of the pathology is characterized by a significant decrease in microviscosity in the area of protein-lipid interaction.Conclusion. Multidirectional age-related changes in cardiomyocyte mitochondria of rats with heart failure were revealed. It was shown that mitochondria in younger rats retain their functional activity in the HF model unlike older rats.

Effects of Subnormothermic Regulated Hepatic Reperfusion on Mitochondrial and Transcriptomic Profiles in a Porcine Model.

We sought to investigate the biological effects of pre-reperfusion treatments of the liver after warm and cold ischemic injuries in a porcine donation after circulatory death model. Donation after circulatory death represents a severe form of liver ischemia and reperfusion injury that has a profound impact on graft function after liver transplantation. Twenty donor pig livers underwent 60 minutes of in situ warm ischemia after circulatory arrest and 120 minutes of cold static preservation prior to simulated transplantation using an ex vivo perfusion machine. Four reperfusion treatments were compared: Control-Normothermic (N), Control- Subnormothermic (S), regulated hepatic reperfusion (RHR)-N, and RHR-S (n = 5 each). The biochemical, metabolic, and transcriptomic profiles, as well as mitochondrial function were analyzed. Compared to the other groups, RHR-S treated group showed significantly lower post-reperfusion aspartate aminotransferase levels in the reperfusion effluent and histologic findings of hepatocyte viability and lesser degree of congestion and necrosis. RHR-S resulted in a significantly higher mitochondrial respiratory control index and calcium retention capacity. Transcriptomic profile analysis showed that treatment with RHR-S activated cell survival and viability, cellular homeostasis as well as other biological functions involved in tissue repair such as cytoskeleton or cytoplasm organization, cell migration, transcription, and microtubule dynamics. Furthermore, RHR-S inhibited organismal death, morbidity and mortality, necrosis, and apoptosis. Subnormothermic RHR mitigates IRI and preserves hepatic mitochondrial function after warm and cold hepatic ischemia. This organ resuscitative therapy may also trigger the activation of protective genes against IRI. Sub- normothermic RHR has potential applicability to clinical liver transplantation.

Polyphenols as bioactive food components in relation to autism spectrum disorders: An overview of the literature

Autism spectrum disorder (ASD) known as a set of behavioral and neurocognitive problems that are identified by challenges in difficulties interacting and communicating with others, as well as heightened repetitive and/or restrictive behaviors. Elevated immune reaction and enhancements in pro-inflammatory cytokines have been discovered in the brains of those who have ASD. A recent article associated autism with abnormalities in mitochondrial respiratory control. Based on various studies, mitochondrial dysfunction is caused by oxidative stress, inadequate nutrition, insufficiency of vitamins, compromised immune system, contact with harmful environmental substances, and modified calcium signaling. Polyphenols found in our diet are active compounds that have the potential to prevent and treat various chronic illnesses including, neurodegenerative and neurodevelopmental problems. This is mainly due to their ability to regulate crucial pathways that cause inflammation and oxidation in the body. The application of polyphenols may result in a reduction of neuroinflammation, facilitating an improvement in the manifestations of ASD. This review focused on the preclinical and clinical studies that documented the beneficial impacts of diet related for the modulation of ASD.

Caffeine improves mitochondrial function in PINK1B9-null mutant Drosophila melanogaster.

Mitochondrial dysfunction plays a central role in Parkinson's disease (PD) and can be triggered by xenobiotics and mutations in mitochondrial quality control genes, such as the PINK1 gene. Caffeine has been proposed as a secondary treatment to relieve PD symptoms mainly by its antagonistic effects on adenosine receptors (ARs). Nonetheless, the potential protective effects of caffeine on mitochondrial dysfunction could be a strategy in PD treatment but need further investigation. In this study, we used high-resolution respirometry (HRR) to test caffeine's effects on mitochondrial dysfunction in PINK1B9-null mutants of Drosophila melanogaster. PINK1 loss-of-function induced mitochondrial dysfunction in PINK1B9-null flies observed by a decrease in O2 flux related to oxidative phosphorylation (OXPHOS) and electron transfer system (ETS), respiratory control ratio (RCR) and ATP synthesis compared to control flies. Caffeine treatment improved OXPHOS and ETS in PINKB9-null mutant flies, increasing the mitochondrial O2 flux compared to untreated PINKB9-null mutant flies. Moreover, caffeine treatment increased O2 flux coupled to ATP synthesis and mitochondrial respiratory control ratio (RCR) in PINK 1B9-null mutant flies. The effects of caffeine on respiratory parameters were abolished by rotenone co-treatment, suggesting that caffeine exerts its beneficial effects mainly by stimulating the mitochondrial complex I (CI). In conclusion, we demonstrate that caffeine may improve mitochondrial function by increasing mitochondrial OXPHOS and ETS respiration in the PD model using PINK1 loss-of-function mutant flies.

Kinin B1 receptor modulates mitochondrial activity responsivity in fasting and voluntary exercise

The Kallikrein-Kinin System (KKS) plays an important role in energy metabolism. We have previously described the importance of the kinin B1 receptor (B1R) in metabolism regulation. Considering that the liver manages the different energy demands of different body tissues, we combined two stressful conditions – fasting and voluntary exercise – to address how B1R may affect liver metabolism, focusing on mitochondrial function. AimsTo investigate how the kinin B1 receptor (B1R) modulates mitochondrial activity under stress conditions, focusing on the rate of energy expenditure and shift in metabolism. Main methodsWild-type and B1R-knockout (B1KO) male mice remained in a calorimetric cage with a wheel for 7 days; 48 h before euthanasia, half of the animals from both groups were submitted to fasting conditions. Mitochondrial activity, ketone bodies, and gene expression involving mitochondrial activity were evaluated. Key findingsB1R modulates the mitochondrial activity under fasting and voluntary exercise, reducing the VO2 expenditure and HEAT. B1KO animals who exercised and underwent fasting did not have increased glucose levels, suggesting a preference for lipids as an energy source. Moreover, these animals displayed RER around 0.8, which indicates a β-oxidation increment. Interestingly, the lack of B1R did not induce mitochondrial activity and biogenesis, suggesting interference in metabolism responsivity, a condition modulated by sirtuins under PGC-1α control. SignificanceB1R modulates mitochondrial respiratory control ratios, which suggests metabolic suppression, influencing hepatic metabolism and, consequently, energy homeostasis.

Hyperbaric oxygen rapidly improves tissue-specific insulin sensitivity and mitochondrial capacity in humans with type 2 diabetes: a randomised placebo-controlled crossover trial

Aims/hypothesisHyperbaric oxygen (HBO) therapy may improve hyperglycaemia in humans with type 2 diabetes, but underlying mechanisms are unclear. Our objective was to examine the glucometabolic effects of HBO on whole-body glucose disposal in humans with type 2 diabetes.MethodsIn a randomised placebo-controlled crossover trial located at the German Diabetes Center, 12 male individuals with type 2 diabetes (age 18–75 years, BMI <35 kg/m2, HbA1c 42–75 mmol/mol [6–9%]), randomly allocated by one person, underwent 2-h HBO, once with 100% (240 kPa; HBO) and once with 21% oxygen (240 kPa; control, CON). Insulin sensitivity was assessed by hyperinsulinaemic–euglycaemic clamps with d-[6,6-2H2]glucose, hepatic and skeletal muscle energy metabolism were assessed by 1H/31P-magnetic resonance spectroscopy, while high-resolution respirometry measured skeletal muscle and white adipose tissue (WAT) mitochondrial capacity. All participants and people assessing the outcomes were blinded.ResultsHBO decreased fasting blood glucose by 19% and increased whole-body, hepatic and WAT insulin sensitivity about one-third (p<0.05 vs CON). Upon HBO, hepatic γ-ATP concentrations doubled, mitochondrial respiratory control doubled in skeletal muscle and tripled in WAT (p<0.05 vs CON). HBO increased myocellular insulin-stimulated serine-473/threonine-308 phosphorylation of Akt but decreased basal inhibitory serine-1101 phosphorylation of IRS-1 and endoplasmic reticulum stress (p<0.05 vs CON).Conclusions/interpretationHBO-mediated improvement of insulin sensitivity likely results from decreased endoplasmic reticulum stress and increased mitochondrial capacity, possibly leading to low-dose reactive oxygen species-mediated mitohormesis in humans with type 2 diabetes.Trial registrationClinicalTrials.gov NCT04219215FundingGerman Federal Ministry of Health, German Federal Ministry of Education and Research, North-Rhine Westfalia Ministry of Culture and Science, European-Regional-Development-Fund, German-Research-Foundation (DFG), Schmutzler StiftungGraphical abstract

Protective effect of low-dose radiation on doxorubicin-induced brain injury in mice

BackgroundTo investigate the protective effect of low-dose radiation (LDR) on brain injury in mice induced by doxorubicin (DOX). MethodsSixty female BALB/C mice were randomly divided into the control (CTR) group, low-dose radiation (LDR) group, doxorubicin treatment (DOX) group and low-dose radiation before doxorubicin treatment (COM) group. After 72 h of exposure to 75 mGy, the mice were intraperitoneally injected with 7.5 mg/kg of doxorubicin and sacrificed 5 days later. Neuron-specific enolase (NSE), lactate dehydrogenase (LDH), adenosine triphosphate (ATP), neurotransmitters, inflammatory mediators, apoptosis- and oxidative stress-related mediators as well as mitochondrial dysfunction were examined. ResultsCompared to the DOX group, the concentrations of DA, 5-HT, EPI and GABA in the COM group were significantly decreased, and the number of TUNEL-positive cells was decreased. In addition, the expression of proapoptotic proteins was downregulated in the COM group compared to the DOX group. Low-dose radiation in advance reduced reactive oxygen species and activated the SOD antioxidant defense system as indicated by significantly reduced GSH expression, increased GSSG expression, increased GPx expression and activation of the Nrf2 redox pathway. After low-dose radiation, the expression levels of ATP5f1, NDUFV1 and CYC1 were close to normal, and the mitochondrial respiratory control rate (RCR) and activity of respiratory chain complex enzymes also tended to be normal. Low-dose radiation upregulated the expression levels of IL-2 and IL-4 but downregulated the expression levels of IL-10 and TGF-β. ConclusionLDR has a protective effect on brain injury in mice treated with DOX. The mechanism is related to LDR alleviating mitochondrial dysfunction and oxidative stress, which promotes the production of antioxidant damage proteins, thus exerting an adaptive protective effect on cells.

Standardization and validation of novel ex-vivo method for mitochondrial bioenergetics using mitochondrial modulators

Mitochondria is an essential organelle; it produces 95% of the adenine triphosphate (ATP) of cells, their dysfunction is related to the pathogenesis of multiple diseases, such as diabetes mellitus, cardiovascular and neurological disorders. Various pharmacologic agents are known to target mitochondrial function. Moreover, the toxic side effects of multiple drugs used to treat diseases are related to the impairment of mitochondrial function. Thus, there is a need to develop a method to evaluate the effect of pharmacologic agents for their potential and side effects to identify effective mitochondrial-modulating agents. Therefore, the objective of this study was to develop and validate an ex-vivo method for studying the effect of pharmacologic agents on mitochondrial function and rescue of dysfunction. Dimethyl sulfoxide (DMSO) concentrations that drugs were soluble in and maintained mitochondrial function were determined. Metformin (MET) is a known mitochondrial complex-1 inhibitor tested for its ability to compromise mitochondrion function. Coenzyme Q10 (Q10) and Resveratrol (RSV), which are known to enhance mitochondrial function, were added alone and dose-dependent, tested for the ability to rescue metformin-induced mitochondrial dysfunction. Ex-vivo liver and brain mitochondrial function was assessed using an oxytherm Clark-type oxygen electrode. DMSO was found to be toxic above 10% and drugs insoluble below 5%. The addition of 0.5 mg/ml MET decreased liver and brain mitochondrial respiratory control rate (RCR). At the same time, Q10 improved RCR in normal mitochondria and a concentration-dependent manner in MET-induced dysfunctional mitochondria. RSV was added in the last step of the experiment to confirm that compromised function is due to MET. Hence this method can be used to screen pharmacological agents for their potential therapeutics or toxic effect on mitochondria.

Long-Lasting Impairments in Quadriceps Mitochondrial Health, Muscle Size, and Phenotypic Composition Are Present After Non-invasive Anterior Cruciate Ligament Injury.

IntroductionDespite rigorous rehabilitation aimed at restoring muscle health, anterior cruciate ligament (ACL) injury is often hallmarked by significant long-term quadriceps muscle weakness. Derangements in mitochondrial function are a common feature of various atrophying conditions, yet it is unclear to what extent mitochondria are involved in the detrimental sequela of quadriceps dysfunction after ACL injury. Using a preclinical, non-invasive ACL injury rodent model, our objective was to explore the direct effect of an isolated ACL injury on mitochondrial function, muscle atrophy, and muscle phenotypic transitions.MethodsA total of 40 male and female, Long Evans rats (16-week-old) were exposed to non-invasive ACL injury, while 8 additional rats served as controls. Rats were euthanized at 3, 7, 14, 28, and 56 days after ACL injury, and vastus lateralis muscles were extracted to measure the mitochondrial respiratory control ratio (RCR; state 3 respiration/state 4 respiration), mitochondrial reactive oxygen species (ROS) production, fiber cross sectional area (CSA), and fiber phenotyping. Alterations in mitochondrial function and ROS production were detected using two-way (sex:group) analyses of variance. To determine if mitochondrial characteristics were related to fiber atrophy, individual linear mixed effect models were run by sex.ResultsMitochondria-derived ROS increased from days 7 to 56 after ACL injury (30–100%, P < 0.05), concomitant with a twofold reduction in RCR (P < 0.05). Post-injury, male rats displayed decreases in fiber CSA (days 7, 14, 56; P < 0.05), loss of IIa fibers (day 7; P < 0.05), and an increase in IIb fibers (day 7; P < 0.05), while females displayed no changes in CSA or phenotyping (P > 0.05). Males displayed a positive relationship between state 3 respiration and CSA at days 14 and 56 (P < 0.05), while females only displayed a similar trend at day 14 (P = 0.05).ConclusionLong-lasting impairments in quadriceps mitochondrial health are present after ACL injury and play a key role in the dysregulation of quadriceps muscle size and composition. Our preclinical data indicate that using mitoprotective therapies may be a potential therapeutic strategy to mitigate alterations in muscle size and characteristic after ACL injury.

Calorie restriction changes lipidomic profiles and maintains mitochondrial function and redox balance during isoproterenol-induced cardiac hypertrophy.

Typically, healthy cardiac tissue utilizes more fat than any other organ. Cardiac hypertrophy induces a metabolic shift leading to a preferential consumption of glucose over fatty acids to support the high energetic demand. Calorie restriction is a dietary procedure that induces health benefits and lifespan extension in many organisms. Given the beneficial effects of calorie restriction, we hypothesized that calorie restriction prevents cardiac hypertrophy, lipid content changes, mitochondrial and redox dysregulation. Strikingly, calorie restriction reversed isoproterenol-induced cardiac hypertrophy. Isolated mitochondria from hypertrophic hearts produced significantly higher levels of succinate-driven H2O2 production, which was blocked by calorie restriction. Cardiac hypertrophy lowered mitochondrial respiratory control ratios, and decreased superoxide dismutase and glutathione peroxidase levels. These effects were also prevented by calorie restriction. We performed lipidomic profiling to gain insights into how calorie restriction could interfere with the metabolic changes induced by cardiac hypertrophy. Calorie restriction protected against the consumption of several triglycerides (TGs) linked to unsaturated fatty acids. Also, this dietary procedure protected against the accumulation of TGs containing saturated fatty acids observed in hypertrophic samples. Cardiac hypertrophy induced an increase in ceramides, phosphoethanolamines, and acylcarnitines (12:0, 14:0, 16:0, and 18:0). These were all reversed by calorie restriction. Altogether, our data demonstrate that hypertrophy changes the cardiac lipidome, causes mitochondrial disturbances, and oxidative stress. These changes are prevented (at least partially) by calorie restriction intervention in vivo. This study uncovers the potential for calorie restriction to become a new therapeutic intervention against cardiac hypertrophy, and mechanisms in which it acts.

A Link between Mitochondrial Dysregulation and Idiopathic Autism Spectrum Disorder (ASD): Alterations in Mitochondrial Respiratory Capacity and Membrane Potential.

Autism spectrum disorder (ASD) is a neurological disorder triggered by various factors through complex mechanisms. Research has been done to elucidate the potential etiologic mechanisms in ASD, but no single cause has been confirmed. The involvement of oxidative stress is correlated with ASD and possibly affects mitochondrial function. This study aimed to elucidate the link between mitochondrial dysregulation and idiopathic ASD by focusing on mitochondrial respiratory capacity and membrane potential. Our findings showed that mitochondrial function in the energy metabolism pathway was significantly dysregulated in a lymphoblastoid cell line (LCL) derived from an autistic child (ALCL). Respiratory capacities of oxidative phosphorylation (OXPHOS), electron transfer of the Complex I and Complex II linked pathways, membrane potential, and Complex IV activity of the ALCL were analyzed and compared with control cell lines derived from a developmentally normal non-autistic sibling (NALCL). All experiments were performed using high-resolution respirometry. Respiratory capacities of OXPHOS, electron transfer of the Complex I- and Complex II-linked pathways, and Complex IV activity of the ALCL were significantly higher compared to healthy controls. Mitochondrial membrane potential was also significantly higher, measured in the Complex II-linked pathway during LEAK respiration and OXPHOS. These results indicate the abnormalities in mitochondrial respiratory control linking mitochondrial function with autism. Correlating mitochondrial dysfunction and autism is important for a better understanding of ASD pathogenesis in order to produce effective interventions.

Abstract 11067: ABCB10 Overexpression Prevents Acute Doxorubicin-Induced Cardiac Dysfunction

Introduction: Doxorubicin (DOX) is a highly effective chemotherapy agent used to treat solid tumor cancers and hematological malignancies. However, DOX treatment can cause adverse cardiac events, which can negatively affect patient outcomes by limiting cancer treatment and reducing overall survival. DOX-induced cardiotoxicity occurs due to its off-target accumulation within cardiomyocytes following administration. Within the heart, DOX predominantly localizes within the mitochondria where it promotes cellular injury via the production of reactive oxygen species (ROS). Currently, there is no clinically approved therapy to prevent this debilitating condition. Therefore, work is needed to identify therapeutic countermeasures to prevent DOX cardiotoxicity. In this regard, ABCB10 is a mitochondria-localized ATP-binding cassette transporter that is hypothesized to play a role in the maintenance of mitochondrial redox balance and iron homeostasis. Hypothesis: We hypothesize that cardiac overexpression of ABCB10 would reduce DOX-induced oxidative damage and preserve cardiac function. Methods: Cause and effect were determined by overexpressing ABCB10 in the heart using an AAV9-MHCK7-ABCB10 construct. Acute effects of DOX (20 mg/kg i.p.) on the heart were assessed by echocardiography. Results: Our findings confirm that DOX treatment results in detriments to both cardiac and mitochondrial function 48-hours following administration. Importantly, cardiac overexpression of ABCB10 was sufficient to prevent the DOX-induced reduction in mitochondrial respiratory control ratio. In addition, both left ventricular fractional shortening percentage and myocardial performance index were preserved in ABCB10 overexpressing animals treated acutely with DOX. Conclusions: ABCB10 overexpression in the heart is an effective intervention to prevent cardiotoxicity and mitochondrial dysfunction acutely following DOX chemotherapy treatment.

Ketone Ester D-β-Hydroxybutyrate-(R)-1,3 Butanediol Prevents Decline in Cardiac Function in Type 2 Diabetic Mice.

BackgroundHeart failure is responsible for approximately 65% of deaths in patients with type 2 diabetes mellitus. However, existing therapeutics for type 2 diabetes mellitus have limited success on the prevention of diabetic cardiomyopathy. The aim of this study was to determine whether moderate elevation in D‐β‐hydroxybutyrate improves cardiac function in animals with type 2 diabetes mellitus.Methods and ResultsType 2 diabetic (db/db) and their corresponding wild‐type mice were fed a control diet or a diet where carbohydrates were equicalorically replaced by D‐β‐hydroxybutyrate‐(R)‐1,3 butanediol monoester (ketone ester [KE]). After 4 weeks, echocardiography demonstrated that a KE diet improved systolic and diastolic function in db/db mice. A KE diet increased expression of mitochondrial succinyl‐CoA:3‐oxoacid‐CoA transferase and restored decreased expression of mitochondrial β‐hydroxybutyrate dehydrogenase, key enzymes in cardiac ketone metabolism. A KE diet significantly enhanced both basal and ADP‐mediated oxygen consumption in cardiac mitochondria from both wild‐type and db/db animals; however, it did not result in the increased mitochondrial respiratory control ratio. Additionally, db/db mice on a KE diet had increased resistance to oxidative and redox stress, with evidence of restoration of decreased expression of thioredoxin and glutathione peroxidase 4 and less permeability transition pore activity in mitochondria. Mitochondrial biogenesis, quality control, and elimination of dysfunctional mitochondria via mitophagy were significantly increased in cardiomyocytes from db/db mice on a KE diet. The increase in mitophagy was correlated with restoration of mitofusin 2 expression, which contributed to improved coupling between cytosolic E3 ubiquitin ligase translocation into mitochondria and microtubule‐associated protein 1 light chain 3–mediated autophagosome formation.ConclusionsModerate elevation in circulating D‐β‐hydroxybutyrate levels via KE supplementation enhances mitochondrial biogenesis, quality control, and oxygen consumption and increases resistance to oxidative/redox stress and mPTP opening, thus resulting in improvement of cardiac function in animals with type 2 diabetes mellitus.

Hypoxic acclimation improves mitochondrial bioenergetic function in large yellow croaker Larimichthys crocea under Cu stress

The purpose of this study was to investigate how pre-hypoxia exposure affected the mitochondrial structure and bioenergetic function of large yellow croaker in responding to Cu stress. Fish were acclimated to normoxia and 3.0 mg DO L−1 for 48 h, then subjected to 0 and 120 μg Cu L−1 for another 48 h. Hypoxic acclimation did not affect mitochondrial ultrastructure and reactive oxygen species (ROS), but reduced oxidative phosphorylation (OXPHOS) efficiency. Cu exposure impaired mitochondrial ultrastructure, increased ROS generation and inhibited OXPHOS efficiency. Compared with Cu exposure alone, hypoxic acclimation plus Cu exposure reduced ROS production and improved OXPHOS efficiency by enhancing mitochondrial respiratory control ratio, mitochondrial membrane potential, and activities and gene expressions of electron transport chain enzymes. In conclusion, hypoxic acclimation improved the mitochondrial energy metabolism of large yellow croaker under Cu stress, facilitating our understanding of the molecular mechanisms regarding adaptive responses of hypoxia-acclimated fish under Cu stress.

Human Platelet Mitochondrial Function Reflects Systemic Mitochondrial Alterations: A Protocol for Application in Field Studies.

Human blood cells may offer a minimally invasive strategy to study systemic alterations of mitochondrial function. Here we tested the reliability of a protocol designed to study mitochondrial respiratory control in human platelets (PLTs) in field studies, using high-resolution respirometry (HRR). Several factors may trigger PLT aggregation during the assay, altering the homogeneity of the cell suspension and distorting the number of cells added to the two chambers (A, B) of the Oroboros Oxygraph-2k (O2k). Thus, inter-chamber variability (∆ab) was calculated by normalizing oxygen consumption to chamber volume (JO2) or to a specific respiratory control state (flux control ratio, FCR) as a reliable parameter of experimental quality. The method’s reliability was tested by comparing the ∆ab of laboratory-performed experiments (LAB, N = 9) to those of an ultramarathon field study (three sampling time-points: before competition (PRE, N = 7), immediately after (POST, N = 10) and 24 h after competition (REC; N = 10)). Our results show that ∆ab JO2 changed PRE-POST, but also for LAB-POST and LAB-REC, while all ∆ab FCR remained unchanged. Thus, we conclude that our method is reliable for assessing PLT mitochondrial function in LAB and field studies and after systemic stress conditions.