Mitochondrial Enzyme Activities Research Articles

НЕКОТОРЫЕ МОРФОФУНКЦИОНАЛЬНЫЕ ОСОБЕННОСТИ МИТОХОНДРИЙ, ИХ СВЯЗЬ С РЕПРОДУКТИВНОЙ ФУНКЦИЕЙ ЖЕНЩИН

Introduction. Mitochondrial morphology and metabolism can have a decisive influence on energy metabolism and reproductive function in women. The objective of this study is to characterize the metabolic and energy metabolism processes in women of reproductive age and those in perimenopause. Methods. The study involved 100 women divided into two equal groups: women of reproductive age and women in perimenopause. Results. All participants had regular menstrual cycles. The duration of menopause in the second group was 1-3 years, with an onset age of 45 years. In total, 64% of the women in group 2 had neurohumoral abnormalities and obesity. Moderate to severe menopause symptoms were detected in 56% of women. Group 2 had reduced activity of mitochondrial enzymes in lymphocytes, such as succinate dehydrogenase and α-glycerophosphate dehydrogenase, while protein, glucose, and uric acid were above normal. Conclusion. This finding suggests that mitochondrial enzymes in group 2 become less active with age. At the end of the reproductive age, the intensity of the energy processes decreases. Cell energy metabolism remains an important area as further research, as this process can shift the timing of reproductive aging in women.

Differential manifestation of RONS and antioxidant enzymes in response to singular versus combinatorial stress in Chironomus ramosus

In nature, organisms face multiple abiotic stress concurrently. Our previous study has indicated how threshold level of lethality depends on the type and combination of stressors. Many mechanisms exist by which organisms respond to stressors and maintain homeostasis. We examined the homeostatic pliability in an extremophilic oriental midge Chironomus ramosus larvae under various combinatorial stress conditions of desiccation (DS), heat (HS) and starvation (SS). Exposure to these stressors led to activation of a common response pathway of oxidative stress. Abundance of antioxidant enzymes like superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase along with selective as well as stressor specific increase in total antioxidant capacity were reflected from the corresponding level of reactive oxygen and nitrogen species (RONS) in larvae exposed to various combinatorial stress. Additionally, we found stressor specific increment in lipid peroxidation level, protein carbonyl content and advanced oxidative protein products during the stress regime. Further investigation revealed a sharp decline in the activity of mitochondrial aconitase enzyme activity in response to abiotic stress induced oxidative stress. The combinatorial stressor specific comparative study based on biochemical and fluorescence based redox-endpoint assays confirmed that the generation of oxidative stress is the consequential convergent pathway of DS, HS and SS, but the quantum of RONS decides the redox potential of homeostatic response and survival rate.

Comparative assessment of the effect of titanium dioxide – based nanoparticles on boar germ cells in vitro

Modern titanium dioxide nanomaterials, in particular modified with nanosilver, have antiviral, antibacterial, antifungal activity, cytotoxic effects in vitro experiments and can affect germ cells of warm-blooded laboratory animals. The research aims to study the effect of different types of titanium dioxide nanoparticles on the physiological and biochemical characteristics of wild boar germ cells in vitro. When applying the maximum dose (LD50) of the studied nanopowders in all samples, sperm survival was probably lower than in the control: by 41.9% (р<0.001) ‒ under the action of TiO2 nanoparticles (hereinafter NPs) (Frantsevich Institute for Problems of Materials Science of NAS of Ukraine, hereinafter IPM), by 28.0% (р<0.05) ‒ under the action of TiO2 NPs (Acros Organics), by 53.5% (р<0.001) ‒ under the action of 4% Ag-TiO2 NPs (IPM) and by 55.9% (р<0.001) ‒ are the action of NPs 8% Ag-TiO2 (IPM). Nanopowders of different based on titanium dioxide manufacturers, characterized by similar morphological characteristics and varying degrees of nanosilver addition (Ag content from 0 to 8%), starting from a dose of 1/10 LD50, can have a damaging effect on the germ cells of wild boars, which is manifested by a decrease in the respiratory activity of sperm and cytochrome oxidase activity, by increasing succinate dehydrogenase activity. The most sensitive marker was the sperm survival rate, the value of which significantly decreased under the action of 8% Ag-TiO2 nanoparticles (IPM) at a dose of 1/100 LD50, which is a consequence of disruption of the activity of mitochondrial enzymes and, accordingly, resynthesis of ATP. Our results confirm and extend the data on the nature of the damaging effect of titanium dioxide-based nanoparticles on germ cells of warm-blooded animals due to oxidative stress. The obtained experimental data will be taken into account in the hygienic regulation of the investigated nanopowders.

The unbroken Krebs cycle. Hormonal-like regulation and mitochondrial signaling to control mitophagy and prevent cell death.

The tricarboxylic acid (TCA) or Krebs cycle, which takes place in prokaryotic cells and in the mitochondria of eukaryotic cells, is central to life on Earth and participates in key events such as energy production and anabolic processes. Despite its relevance, it is not perceived as tightly regulated compared to other key metabolisms such as glycolysis/gluconeogenesis. A better understanding of the functioning of the TCA cycle is crucial due to mitochondrial function impairment in several diseases, especially those that occur with neurodegeneration. This article revisits what is known about the regulation of the Krebs cycle and hypothesizes the need for large-scale, rapid regulation of TCA cycle enzyme activity. Evidence of mitochondrial enzyme activity regulation by activation/deactivation of protein kinases and phosphatases exists in the literature. Apart from indirect regulation via G protein-coupled receptors (GPCRs) at the cell surface, signaling upon activation of GPCRs in mitochondrial membranes may lead to a direct regulation of the enzymes of the Krebs cycle. Hormonal-like regulation by posttranscriptional events mediated by activable kinases and phosphatases deserve proper assessment using isolated mitochondria. Also see the video abstract here: https://youtu.be/aBpDSWiMQyI.

Effects of glutathione on mitochondrial DNA and antioxidant enzyme activities in Drosophila melanogaster

The free radical theory in aging assumes that the accumulation of macromolecular damage induced by toxic reactive oxygen species plays a central role in the aging process. The intake of nutritional antioxidants can prevent this damage by neutralizing reactive oxygen derivatives. Glutathione (GSH; en-L-Glutamyl-L-cysteinyl glycine) is the lowest molecular weight thiol in the cells and as a cofactor of many enzymes and a potent antioxidant plays an important role in maintaining normal cell functions by destroying toxic oxygen radicals. In this study, the effects of GSH on SOD, GST and catalase enzymes and mtDNA damage were investigated at various time intervals by giving reduced glutathione to Drosophila. It was observed that 3-week GSH administration did not have a statistically significant effect on SOD and GST activities whereas GSH application decreased the catalase enzyme activities significantly. Although the decrease in antioxidant capacity with age was observed in SOD and catalase enzymes, such a situation was not observed in GST enzyme activities. There was no statistically significant difference between the control and GSH groups in mtDNA copy number values, while in the GSH group, oxidative mtDNA damage was high. These results may be due to the prooxidant effect of GSH at the dose used in this study.

Effects of blueberry anthocyanins on perfluorooctane sulfonate-induced oxidative stress and mitochondrial dysfunction in dugesia japonica

The effects of blueberry anthocyanins against perfluorooctane sulfonate on antioxidant-related gene expression levels, antioxidase activities, malondialdehyde content, glutathione/oxidized glutathione ratios, mitochondrial metabolic enzyme activities, and mitochondrial permeability transition pore opening rates were examined in the planarian Dugesia japonica. Glutathione reductase, glutathione peroxidase, and glutathione S-transferase gene expression levels were up-regulated on day 1 and then down-regulated following exposure to 5 mg/L perfluorooctane sulfonate with those of the control. The activities of the three corresponding enzymes were inhibited by perfluorooctane sulfonate and activated by anthocyanins. Malondialdehyde contents and mitochondrial permeability transition pore opening rates as well as the activities of mitochondrial metabolic enzymes, also increased and the glutathione/oxidized glutathione ratio decreased. Anthocyanin treatments have an alleviating effect on the disorder caused by perfluorooctane sulfonate.

EGFR-targeted bacteriophage lambda penetrates model stromal and colorectal carcinoma tissues, is taken up into carcinoma cells, and interferes with 3-dimensional tumor formation.

Colorectal cancer and other adult solid cancers pose a significant challenge for successful treatment because the tumor microenvironment both hinders the action of conventional therapeutics and suppresses the immune activities of infiltrating leukocytes. The immune suppression is largely the effect of enhanced local mediators such as purine nucleosides and eicosanoids. Genetic approaches have the promise of interfering with these mechanisms of local immunosuppression to allow both intrinsic and therapeutic immunological anticancer processes. Bacterial phages offer a novel means of enabling access into tissues for therapeutic genetic manipulations. We generated spheroids of fibroblastic and CRC cancer cells to model the 3-dimensional stromal and parenchymal components of colorectal tumours. We used these to examine the access and effects of both wildtype (WT) and epidermal growth factor (EGF)-presenting bacteriophage λ (WT- λ and EGF-λ) as a means of delivery of targeted genetic interventions in solid cancers. We used both confocal microscopy of spheroids exposed to AF488-tagged phages, and the recovery of viable phages as measured by plaque-forming assays to evaluate access; and measures of mitochondrial enzyme activity and cellular ATP to evaluate the outcome on the constituent cells. Using flourescence-tagged derivatives of these bacteriophages (AF488-WT-λ and AF488-EGF-λ) we showed that phage entry into these tumour microenvironments was possible and that the EGF ligand enabled efficient and persistent uptake into the cancer cell mass. EGF-λ became localized in the intracellular portion of cancer cells and was subjected to subsequent cellular processing. The targeted λ phage had no independent effect upon mature tumour spheroids, but interfered with the early formation and growth of cancer tissues without the need for addition of a toxic payload, suggesting that it might have beneficial effects by itself in addition to any genetic intervention delivered to the tumour. Interference with spheroid formation persisted over the duration of culture. We conclude that targeted phage technology is a feasible strategy to facilitate delivery into colorectal cancer tumour tissue (and by extension other solid carcinomas) and provides an appropriate delivery vehicle for a gene therapeutic that can reduce local immunosuppression and/or deliver an additional direct anticancer activity.

Low-frequency electrical stimulation of bilateral hind legs by belt electrodes is effective for preventing denervation-induced atrophies in multiple skeletal muscle groups in rats.

Belt electrode skeletal muscle electrical stimulation (B-SES) can simultaneously contract multiple muscle groups. Although the beneficial effects of B-SES in clinical situations have been elucidated, its molecular mechanism remains unknown. In this study, we developed a novel rodent B-SES ankle stimulation system to test whether low-frequency stimulation prevents denervation-induced muscle atrophy. Electrical stimulations (7‒8Hz, 30min) with ankle belt electrodes were applied to Sprague-Dawley rats daily for one week. All animals were assigned to the control (CONT), denervation-induced atrophy (DEN), and DEN + electrical stimulation (ES) groups. The tibialis anterior (TA) and gastrocnemius (GAS) muscles were used to examine the effect of ES treatment. After seven daily sessions of continuous stimulation, muscle wet weight (n = 8-11), and muscle fiber cross-sectional area (CSA, n = 4-6) of TA and GAS muscles were lower in DEN and DEN + ES than in CON. However, it was significantly higher in DEN than DEN + ES, showing that ES partially prevented muscle atrophy. PGC-1α, COX-IV, and citrate synthase activities (n = 6) were significantly higher in DEN + ES than in DEN. The mRNA levels of muscle proteolytic molecules, Atrogin-1 and Murf1, were significantly higher in DEN than in CONT, while B-SES significantly suppressed their expression (p < 0.05). In conclusion, low-frequency electrical stimulation of the bilateral ankles using belt electrodes (but not the pad electrodes) is effective in preventing denervation-induced atrophy in multiple muscles, which has not been observed with pad electrodes. Maintaining the mitochondrial quantity and enzyme activity by low-frequency electrical stimulation is key to suppressing muscle protein degradation.

In Skeletal Muscle Fibers, Protein Kinase Subunit CSNK2A1/CK2α Is Required for Proper Muscle Homeostasis and Structure and Function of Neuromuscular Junctions.

CSNK2 tetrameric holoenzyme is composed of two subunits with catalytic activity (CSNK2A1 and/or CSNK2A2) and two regulatory subunits (CSNK2B) and is involved in skeletal muscle homeostasis. Up-to-date, constitutive Csnk2a2 knockout mice demonstrated mild regenerative impairments in skeletal muscles, while conditional Csnk2b mice were linked to muscle weakness, impaired neuromuscular transmission, and metabolic and autophagic compromises. Here, for the first time, skeletal muscle-specific conditional Csnk2a1 mice were generated and characterized. The ablation of Csnk2a1 expression was ensured using a human skeletal actin-driven Cre reporter. In comparison with control mice, first, conditional knockout of CSNK2A1 resulted in age-dependent reduced grip strength. Muscle weakness was accompanied by impaired neuromuscular transmission. Second, the protein amount of other CSNK2 subunits was aberrantly changed. Third, the number of central nuclei in muscle fibers indicative of regeneration increased. Fourth, oxidative metabolism was impaired, reflected by an increase in cytochrome oxidase and accumulation of mitochondrial enzyme activity underneath the sarcolemma. Fifth, autophagic processes were stimulated. Sixth, NMJs were fragmented and accompanied by increased synaptic gene expression levels. Altogether, knockout of Csnk2a1 or Csnk2b results in diverse impairments of skeletal muscle biology.

Bivalves Transmissible Neoplasia: Biochemical Aspects of Contagious Cancer in a Clam Macoma Balthica.

Occurring in marine invertebrates infectious haemic neoplasia (bivalves transmissible neoplasia, BTN) arises from genome instabilities leading to multilevel malfunctions and unregulated cell division of presumably haemocyte precursors. As its biochemical characterisation remains unknown, we here present the first data describing selected aspects of the physiology and biochemistry of the disease a in model clam Macoma balthica. We chose free amino acids (FAA) composition, mitochondrial respiration and enzymatic activity, oxidative stress enzymes activities and corticosteroids profile as markers of this contagious cancer. Selected markers were measured in neoplastic and healthy clams and two tissue types, haemolymph and solid tissue. FAA composition was assessed in the haemolymph samples using high performance liquid chromatography-mass spectrometry (LC/MS). Mitochondrial respiration analysis was performed on haemocytes using oxygen electrodes integrated system Seahorse XFp. Mitochondrial enzymes activities were measured using spectrophotometry (cytochrome oxidase, COX) and commercial kit (succinate dehydrogenase, SDH). Total Antioxidant Capacity (TAC), Acetylocholinesterase (AChE), Protein Carbonyl Content (CBO) and Malondialdehyde (MDA) levels were measured in the solid tissue using analytical kits, and glutathione (GSH) was measured spectrophotometrically. Corticosteroids profile, measured in the solid tissue, was obtained with Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (HPLC-ESI-MS/MS) technique. In both clam groups nine FAAs were detected with Asp, Glu, Pro, Ser constituting over 90% of total FAA content. Significantly higher Gln level was detected in BTN positive clams. In neoplastic clams, an impairment of mitochondrial metabolism was observed as a decrease in mitochondrial oxygen consumption and lower cytochrome c oxidase activity. In the neoplastic clams significantly higher concentration of low molecular weight antioxidants was found. Finally, we report high level of corticosterone and lower levels of dehydrocorticosterone, cortisol and cortisone in healthy clams and elevated cortisol level in BTN individuals. Neoplastic clams are characterized by altered mitochondrial metabolism, with a potential key role of glutamine (Gln) in cancer cells energy production. Despite low aerobic respiration, BTN cells have efficient antioxidative response to elevated concentration of ROS. Elevated cortisol level in BTN-positive clams may indicate an important role of this corticosteroid in cancer biochemistry. Thus, we here provide the first results of selected physiological and biochemical aspects of BTN, making an important step in studying cancer epidemiology in wildlife.

Branched-chain amino acid supplementation suppresses the detraining-induced reduction of mitochondrial content in mouse skeletal muscle.

Exercise training enhances oxidative capacity whereas detraining reduces mitochondrial content in skeletal muscle. The strategy to suppress the detraining-induced reduction of mitochondrial content has not been fully elucidated. As previous studies reported that branched-chain amino acid (BCAA) ingestion increased mitochondrial content in skeletal muscle, we evaluated whether BCAA supplementation could suppress the detraining-induced reduction of mitochondrial content. Six-week-old male Institute of Cancer Research (ICR) mice were randomly divided into four groups as follows: control (Con), endurance training (Tr), detraining (DeTr), and detraining with BCAA supplementation (DeTr + BCAA). Mice in Tr, DeTr, and DeTr + BCAA performed treadmill running exercises [20-30 m/min, 60 min, 5 times/week, 4 weeks]. Then, mice in DeTr and DeTr + BCAA were administered with water or BCAA [0.6mg/g of body weight, twice daily] for 2 weeks of detraining. In whole skeletal muscle, mitochondrial enzyme activities and protein content were decreased after 2 weeks of detraining, but the reduction was suppressed by BCAA supplementation. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) protein content, a master regulator of mitochondrial biogenesis, was decreased by detraining irrespective of BCAA ingestion. Regarding mitochondrial degradation, BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), a mitophagy-related protein, was significantly higher in the Tr group than in the DeTr + BCAA group, but not different from in the DeTr group. With respect to mitochondrial quality, BCAA ingestion did not affect oxygen consumption rate (OCR) and reactive oxygen species (ROS) production in isolated mitochondria. Our findings suggest that BCAA ingestion suppresses the detraining-induced reduction of mitochondrial content partly through inhibiting mitophagy.

Effects of PBMC mitochondrial autophagy on exercise energy consumption and mitochondrial respiratory chain complex enzyme activity in high altitude migrants

目的: 探究高原移居中青年男性走、跑状态运动能耗及外周血单个核细胞(PBMC)线粒体自噬标志物变化特征。方法: 招募152名受试者,根据移居高原年限分为高原移居Ⅰ组(HM1)、高原移居Ⅱ组(HM2)、高原移居Ⅲ组(HM3)、世居高原组(Con)。检测受试者3.0 km/h 、4.5 km/h、6.0 km/h及7.5 km/h条件下运动能耗;ELISA检测受试者PBMC线粒体NADH-Q氧化还原酶、琥珀酸-Q氧化还原酶、UQ-细胞色素C氧化还原酶、细胞色素C氧化酶水平;RT-PCR和Western blot检测受试者PBMC线粒体Parkin、PINK3、LC3A、LC3B mRNA及蛋白表达水平。结果: 与Con组比较,HM1、HM2组3 km/h步行能耗显著上升(P＜ 0.05);与HM1组比较,HM2组显著降低(P＜0.05) 。与Con组比较,HM1组4.5 km/h、6 km/h及7.5 km/h走、跑能耗均显著上升(P＜0.05) 。与Con组比较,HM1、HM2和HM3组复合物Ⅰ、复合物Ⅱ及复合物Ⅲ水平均显著降低(P＜0.05) ;与HM1组和HM2组比较,HM3组显著上升(P＜0.05) ;与HM1组比较,HM2组显著上升(P＜0.05) 。与Con组比较,HM1、HM2组复合物Ⅳ水平显著降低(P＜0.05) ;与HM1组和HM2组比较,HM3组显著上升(P＜0.05) 。与Con组比较,HM1、HM2和HM3组Parkin mRNA表达显著上升(P＜0.05) ,HM1、HM2组高于HM3组(P＜0.05) ;与Con组比较,HM1、HM2和HM3组PINK3 mRNA表达显著降低(P＜0.05) ,HM1组显著低于HM2、HM3组(P＜0.05) ;与Con组比较,HM1、HM2和HM3组LC3A mRNA表达显著降低(P＜0.05) ,HM1组和HM2组显著低于HM3组,HM1组显著低于HM2组(P＜0.05) ;与Con组比较,HM1、HM2和HM3组LC3B mRNA和LC3B蛋白表达显著上升(P＜0.05) ,HM1组和HM2组显著高于HM3组,HM1组显著低于HM2组(P＜0.05) 。与Con组比较,HM1、HM2组Parkin蛋白表达显著上升(P＜0.05) ,HM1组、HM2组显著高于HM3组(P＜0.05) ;与Con组比较,HM1、HM2组PINK3和LC3A蛋白表达显著降低(P＜0.05) ,HM1组、HM2组显著低于HM3组(P＜0.05) 。结论: 高原移居者随高原移居时间延长,PBMC线粒体自噬水平逐步下降,PBMC线粒体呼吸酶活性逐渐增殖;高原定量负荷运动能量消耗逐渐降低。.

INTERRELATION BETWEEN MITOCHONDRIAL ENZYME ACTIVITY AND ANTIOXIDANT ACTIVITY OF SECONDARY POLYPHENOL NATURE METABOLITES IN HEMIPARASITE VISCUM ALBUM L. LEAVES

Antioxidants are widely used in practical medicine. Not only the search for new plant antioxidants, but also the study of the factors affecting their accumulation in plants, are relevant.The aim is to study the interrelation between the activity of mitochondrial enzymes and the antioxidant activity of the secondary polyphenolic nature metabolites in hemiparasite Viscum Album L. leaves.Materials and methods. The sampling material was Viscum album L. leaves, collected in winter from a host tree, Malus domestica Borkh. The extraction of biologically active substances was carried out with ethyl alcohol of various concentrations (90%, 70% and 50%), or purified water. The amount of total antioxidants was estimated by the amperometric method. The amount of total phenols was evaluated in the reaction with the Folin-Ciocalteu reagent. The concentration of total flavonoids was estimated by the change in the optical density of the rutin with aluminum (III) chloride complex. The antioxidant properties of the analyzed extracts were determined in vitro in the induced lipid peroxidation test. The activity of aconitase was assessed by a conjugated aconitase-isocitrate dehydrogenase reaction, citrate synthase – by changing the color intensity of the Ellman reagent solution, succinate dehydrogenase were determined in the reaction of succinate-dependent oxidation of 2,6-dichlorophenolindophenol.Results. The carried out study showed that the maximum amount of total phenols (2.39±0.05%) is observed in a 50% ethanol extract from Viscum album L. leaves, with the content of total flavonoids equal to 1.83±0.04%, and the antioxidants equal to 0.503±0.007 mg/g (a quercetin equivalent) and 0.322±0.006 mg/g (a gallic acid equivalent). A 50% ethanol extract suppressed lipid peroxidation in the model mixture with IC50=106.3±1.09 µg/ml. In Viscum album L. leaves, a high activity of aconitase which strongly correlated (r=0.88416) with changes in the concentration of flavonoids, has been notified.Conclusion. The optimal extractant for obtaining extracts with a high antioxidant activity is 50% ethyl alcohol. The analysis of the mitochondrial enzymes activity showed that in Viscum album L. leaves collected in winter, a high activity of aconitase strongly correlated with changes in the concentration of flavonoids (r=0.88416).

Myocytic androgen receptor overexpression does not affect sex differences in adaptation to chronic endurance exercise

Muscle-specific androgen receptor (AR) overexpression (HSAAR transgene) in sedentary male rats results in reduced adiposity, increased mitochondrial enzyme activity, and selective increase in Type 2b myofiber size. Here, we tested chronic endurance exercise interactions with this phenotype in both sexes. Across 9 weeks, rats ran 5×/week on motorized running wheels at increasing speeds and durations. Exercise reduced fat mass in all groups, but sex affected endurance exercise outcomes such that absolute lean mass increased only in females and total body mass decreased only in males. Expected sex differences were observed with males exhibiting greater total body and lean mass; absolute and relative fat mass; bone mineral density; extensor digitorum longus (EDL) myofiber size and glycolytic proportion; but lesser Type 2a and Type 1 myosin expression in tibialis anterior. Observed HSAAR outcomes were not altered by sex, with transgenic rats having greater lean mass, Type 2a myosin expression in soleus, and glycolytic myofiber size in EDL. Tibialis AR content was independently affected by sex, HSAAR, and exercise. No sex differences were observed in tibialis AR expression in wild-type rats, although HSAAR males had greater AR content than HSAAR females. We identified a moderate correlation between AR expression and glycolytic myofiber size, but not whole-body composition. Overall, results suggest myocytic AR overexpression and chronic exercise, despite sharing a similar phenotype to adaptation, are mediated by distinct mechanisms. Further, this study illustrates sex differences in adaptation to chronic endurance exercise, and suggests sex-similarity in the relationship between muscle AR and exercise response.

Neonatal ketone body elevation regulates postnatal heart development by promoting cardiomyocyte mitochondrial maturation and metabolic reprogramming

Neonatal heart undergoes metabolic conversion and cell cycle arrest preparing for the increased workload during adulthood. Herein, we report that neonatal ketone body elevation is a critical regulatory factor for postnatal heart development. Through multiomics screening, we found that the expression of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), the rate-limiting enzyme of ketogenesis, was transiently induced by colostrum in the neonatal heart. Hmgcs2 knockout caused mitochondrial maturation defects. Meanwhile, postnatal heart development was compromised and cardiomyocytes reacquired proliferation capacity in Hmgcs2 knockout mice. Consequently, over 40% of newborn Hmgcs2 knockout mice died before weaning. The heart function of surviving Hmgcs2 knockout mice was also impaired, which could be rescued by ketone body supplementation during the suckling stage. Mechanistically, ketone body deficiency inhibited β-hydroxybutyrylation but enhanced acetylation of mitochondrial proteins, which might be responsible for the inhibition of the enzyme activity in mitochondria. These observations suggest that ketone body is critical for postnatal heart development through regulating mitochondrial maturation and metabolic reprogramming.

Effect of caffeine on mitochondrial biogenesis in the skeletal muscle - A narrative review.

Caffeine is one of the most widely used substances as recreational drug for performance-enhancement in sport, underpinned by a strong evidence base. Although the effects of caffeine are widely investigated within the scope of performance physiology, the molecular effects of caffeine within skeletal muscle remain unclear. Evidence from invitro and invivo models suggest that caffeine regulates the glucose metabolism in the skeletal muscle. Moreover, caffeine seems to stimulate CaMKII, PPARδ/β, AMPK and PGC1α, classical markers of exercise-adaptations, including mitochondrial biogenesis and mitochondrial content. This review summarizes evidence to suggest caffeine-effects within skeletal muscle fibers, focusing on the putative role of caffeine on mitochondrial biogenesis to explore whether caffeine supplementation might be a strategy to enhance mitochondrial biogenesis.

Neuroprotective Effect of Polyphenol Extracts from Terminalia chebula Retz. against Cerebral Ischemia-Reperfusion Injury.

Current therapies for ischemic stroke are insufficient due to the lack of specific drugs. This study aimed to investigate the protective activity of polyphenol extracts from Terminalia chebula against cerebral ischemia-reperfusion induced damage. Polyphenols of ethyl acetate and n-butanol fractions were extracted from T. chebula. BV2 microglial cells exposed to oxygen-glucose deprivation/reoxygenation and mice subjected to middle cerebral artery occlusion/reperfusion were treated by TPE and TPB. Cell viability, cell morphology, apoptosis, mitochondrial membrane potential, enzyme activity and signaling pathway related to oxidative stress were observed. We found that TPE and TPB showed strong antioxidant activity in vitro. The protective effects of TPE and TPB on cerebral ischemia-reperfusion injury were demonstrated by enhanced antioxidant enzyme activities, elevated level of the nucleus transportation of nuclear factor erythroid 2-related factor 2 and expressions of antioxidant proteins, with a simultaneous reduction in cell apoptosis and reactive oxygen species level. In conclusion, TPE and TPB exert neuroprotective effects by stimulating the Nrf2 signaling pathway, thereby inhibiting apoptosis.

Effects of Endurance Training on Metabolic Enzyme Activity and Transporter Proteins in Skeletal Muscle of Ovariectomized Mice.

Estrogen deficiency or insufficiency can occur under several conditions, leading to negative health outcomes. To establish an effective countermeasure against estrogen loss, we investigated the effects of endurance training on ovariectomy (OVX)-induced metabolic disturbances. Female Institute of Cancer Research mice underwent OVX or sham operations. On day 7 of recovery, the mice were randomized to remain either sedentary or undergo 5 wk of treadmill running (15-20 m·min -1 , 60 min, 5 d·wk -1 ). During week 5 of the training, all animals performed a treadmill running test (15 m·min -1 , 60 min). After the experimental period, OVX resulted in greater gains in body mass, fat mass, and triglyceride content in the gastrocnemius muscle. OVX enhanced phosphofructokinase activity in the plantaris muscle and decreased lactate dehydrogenase activity in the plantaris and soleus muscles. OVX decreased the protein content of NDUFB8, a mitochondrial respiratory chain subunit, but did not decrease other mitochondrial proteins or enzyme activities. Endurance training significantly enhanced mitochondrial enzyme activity and protein content in the skeletal muscles. Although OVX increased the respiratory exchange ratio during the treadmill running test, and postexercise blood lactate levels, endurance training normalized these parameters. The present findings suggest that endurance training is a viable strategy to counteract the negative metabolic consequences in hypoestrogenism.

277 Live Animal Mitochondrial Markers During the Feedlot Phase are Related to Meat Quality in Angus but not Brahman Steers

Abstract Mitochondrial activity correlates with meat product quality post-harvest but little is known about the relationships between live animal mitochondria and product quality at slaughter. To test the hypothesis that live animal skeletal muscle mitochondrial markers would be correlated with longissimus Warner-Bratzler shear force (WBSF) post-harvest, longissimus thoracis (LT) and trapezius (TRAP) samples were collected from Brahman and Angus steers (n = 36 per breed) during the grazing growth phase (GP) and after 120 days on feed (FP). Samples were analyzed for mitochondrial enzyme activities via colorimetry and for oxidative phosphorylation (P) and electron transfer (E) capacities via high-resolution respirometry. Relationships between mitochondrial variables and WBSF were determined using PROC CORR in SAS (v9.4). Within Angus in GP, LT mitochondrial volume density as measured by citrate synthase activity (CS) was positively correlated with WBSF (P=0.009). In FP, Angus LT intrinsic (relative to CS) P with complex I (PCI) and maximal E with complexes I and II (ECI+II) were positively correlated with WBSF (P≤0.05), while the contribution of maximal P with complexes I and II (PCI+II) to maximal E (flux control ratio, FCRPCI+II) was negatively correlated with WBSF (P=0.03). Also in FP, Angus TRAP integrative (relative to mg tissue) PCI, PCI+II, and ECI+II and FCRPCI were negatively correlated with WBSF (P≤0.02), while the FCR for electron transfer through complex II only (FCRECII) was positively correlated with WBSF (P=0.007). In Brahman, no mitochondrial markers correlated with WBSF during either GP or FP. Post-harvest meat tenderness is related to live animal skeletal muscle mitochondrial markers when evaluated close to slaughter in Angus but not in Brahman steers.

Influence of cerebral infarction on both bladder and urethral activities and changes after tramadol administration in rats.

We investigated the changes in bladder and urethral function after cerebral infarction (CI) and the influence of tramadol on these functions. Twenty-eight female Sprague Dawley rats were divided into normal and CI groups. In the awake condition, metabolic cage study and blood pressure were evaluated. Under urethane anesthesia, the intravenous effect of tramadol (0.01-1 mg/kg), which has both µ-opioid receptor stimulation and inhibition of norepinephrine and serotonin reuptake, on continuous cystometry, and simultaneous measurements of bladder and urethral perfusion pressure (UPP) were recorded. Infarcted lesions were examined by staining with triphenyltetrazolium chloride, a marker of mitochondrial enzyme activity. CI rats showed impaired sympathetic activity with Horner's syndrome and lower blood pressure. In metabolic cage study, urinary frequency during the dark phase was increased in CI rats. On bladder activity, in CI rats, the baseline pressure threshold for inducing bladder contractions was significantly lower (p &lt; 0.01), and the intercontraction interval was prolonged after tramadol administration. On urethral activity, the baseline UPP was significantly lower in CI rats than in normal rats and it did not change after tramadol administration. Residual urine rate was significantly increased in normal rats, but not in CI rats. CI rats showed brain infarction including the cortex and hypothalamus, which is a center of the autonomic nervous system. CI-induced ischemic brain damage results in impairment of both bladder and urethral functions, in addition to decreased sympathetic activity. Bladder overactivity after CI can be improved by tramadol; however, urethral activity cannot be improved by it.