allopurinol and Muscular-Atrophy

Exercise intolerance in patients with heart failure (HF) is partly attributed to skeletal muscle abnormalities. We have shown that reactive oxygen species (ROS) play a crucial role in skeletal muscle abnormalities, but the pathogenic mechanism remains unclear. Xanthine oxidase (XO) is reported to be an important mediator of ROS overproduction in ischaemic tissue. Here, we tested the hypothesis that skeletal muscle abnormalities in HF are initially caused by XO-derived ROS and are prevented by the inhibition of their production.. Myocardial infarction (MI) was induced in male C57BL/6J mice, which eventually led to HF, and a sham operation was performed in control mice. The time course of XO-derived ROS production in mouse skeletal muscle post-MI was first analysed. XO-derived ROS production was significantly increased in MI mice from Days 1 to 3 post-surgery (acute phase), whereas it did not differ between the MI and sham groups from 7 to 28 days (chronic phase). Second, mice were divided into three groups: sham + vehicle (Sham + Veh), MI + vehicle (MI + Veh), and MI + febuxostat (an XO inhibitor, 5 mg/kg body weight/day; MI + Feb). Febuxostat or vehicle was administered at 1 and 24 h before surgery, and once-daily on Days 1-7 post-surgery. On Day 28 post-surgery, exercise capacity and mitochondrial respiration in skeletal muscle fibres were significantly decreased in MI + Veh compared with Sham + Veh mice. An increase in damaged mitochondria in MI + Veh compared with Sham + Veh mice was also observed. The wet weight and cross-sectional area of slow muscle fibres (higher XO-derived ROS) was reduced via the down-regulation of protein synthesis-associated mTOR-p70S6K signalling in MI + Veh compared with Sham + Veh mice. These impairments were ameliorated in MI + Feb mice, in association with a reduction of XO-derived ROS production, without affecting cardiac function.. XO inhibition during the acute phase post-MI can prevent skeletal muscle abnormalities and exercise intolerance in mice with HF.

Topics: Animals; Cell Hypoxia; Cell Line; Disease Models, Animal; Enzyme Inhibitors; Exercise Tolerance; Febuxostat; Male; Mice, Inbred C57BL; Mitochondria, Muscle; Muscle Fibers, Skeletal; Muscle Strength; Muscle, Skeletal; Muscular Atrophy; Myocardial Infarction; Reactive Oxygen Species; Ribosomal Protein S6 Kinases, 70-kDa; Time Factors; TOR Serine-Threonine Kinases; Xanthine Oxidase

Reactive oxygen species (ROS) metabolism is regulated by the oxygen-mediated enzyme reaction and antioxidant mechanism within cells under physiological conditions. Xanthine oxidoreductase (XOR) exhibits two inter-convertible forms (xanthine oxidase (XO) and xanthine dehydrogenase (XDH)), depending on the substrates. XO uses oxygen as a substrate and generates superoxide (O

Topics: Acetophenones; Aging; Allopurinol; Anemia; Animals; Fatty Liver; Mice, Mutant Strains; Muscular Atrophy; NADPH Oxidases; Superoxide Dismutase-1; Superoxides; Xanthine Dehydrogenase

Disuse muscle wasting will likely affect everyone in his or her lifetime in response to pathologies such as joint immobilization, inactivity or bed rest. There are no good therapies to treat it. We previously found that allopurinol, a drug widely used to treat gout, protects muscle damage after exhaustive exercise and results in functional gains in old individuals. Thus, we decided to test its effect in the prevention of soleus muscle atrophy after two weeks of hindlimb unloading in mice, and lower leg immobilization following ankle sprain in humans (EudraCT: 2011-003541-17). Our results show that allopurinol partially protects against muscle atrophy in both mice and humans. The protective effect of allopurinol is similar to that of resistance exercise which is the best-known way to prevent muscle mass loss in disuse human models. We report that allopurinol protects against the loss of muscle mass by inhibiting the expression of ubiquitin ligases. Our results suggest that the ubiquitin-proteasome pathway is an appropriate therapeutic target to inhibit muscle wasting and emphasizes the role of allopurinol as a non-hormonal intervention to treat disuse muscle atrophy.

Topics: Allopurinol; Animals; Ankle Injuries; Hindlimb Suspension; Humans; Mice; Muscle, Skeletal; Muscular Atrophy; Muscular Disorders, Atrophic; Physical Conditioning, Animal; Proteasome Endopeptidase Complex; Ubiquitin

Cancer cachexia is a wasting condition, driven by systemic inflammation and oxidative stress. This study investigated eicosapentaenoic acid (EPA) in combination with oxypurinol as a treatment in a mouse model of cancer cachexia. Mice with cancer cachexia were randomized into 4 treatment groups (EPA (0.4 g/kg/day), oxypurinol (1 mmol/L ad-lib), combination, or control), and euthanized after 29 days. Analysis of oxidative damage to DNA, mRNA analysis of pro-oxidant, antioxidant and proteolytic pathway components, along with enzyme activity of pro- and antioxidants were completed on gastrocnemius muscle. The control group displayed earlier onset of tumor compared to EPA and oxypurinol groups (P<0.001). The EPA group maintained body weight for an extended duration (20 days) compared to the oxypurinol (5 days) and combination (8 days) groups (P<0.05). EPA (18.2±3.2 pg/ml) and combination (18.4±3.7 pg/ml) groups had significantly higher 8-OH-dG levels than the control group (12.9±1.4 pg/ml, P≤0.05) indicating increased oxidative damage to DNA. mRNA levels of GPx1, MURF1 and MAFbx were higher following EPA treatment compared to control (P≤0.05). Whereas oxypurinol was associated with higher GPx1, MnSOD, CAT, XDH, MURF1, MAFbx and UbB mRNA compared to control (P≤0.05). Activity of total SOD was higher in the oxypurinol group (32.2±1.5 U/ml) compared to control (27.0±1.3 U/ml, P<0.01), GPx activity was lower in the EPA group (8.76±2.0 U/ml) compared to control (14.0±1.9 U/ml, P<0.05), and catalase activity was lower in the combination group (14.4±2.8 U/ml) compared to control (20.9±2.0 U/ml, P<0.01). There was no change in XO activity. The increased rate of weight decline in mice treated with oxypurinol indicates that XO may play a protective role during the progression of cancer cachexia, and its inhibition is detrimental to outcomes. In combination with EPA, there was little significant improvement from control, indicating oxypurinol is unlikely to be a viable treatment compound in cancer cachexia.

Topics: Adenocarcinoma; Animals; Cachexia; Catalase; Cell Line, Tumor; Drug Evaluation, Preclinical; Drug Therapy, Combination; Eicosapentaenoic Acid; Enzyme Inhibitors; Female; Gene Expression; Mice; Mice, Inbred BALB C; Mice, Nude; Muscle, Skeletal; Muscular Atrophy; Neoplasm Transplantation; Neoplasms, Experimental; Organ Size; Oxidative Stress; Oxypurinol; Superoxide Dismutase; Tumor Burden; Weight Loss; Xanthine Oxidase

Alterations in muscle play an important role in common diseases and conditions. Reactive oxygen species (ROS) are generated during hindlimb unloading due, at least in part, to the activation of xanthine oxidase (XO). The major aim of this study was to determine the mechanism by which XO activation causes unloading-induced muscle atrophy in rats, and its possible prevention by allopurinol, a well-known inhibitor of this enzyme. For this purpose we studied one of the main redox sensitive signalling cascades involved in skeletal muscle atrophy i.e. p38 MAPKinase, and the expression of two well known muscle specific E3 ubiquitin ligases involved in proteolysis, the Muscle atrophy F-Box (MAFbx; also known as atrogin-1) and Muscle RING (Really Interesting New Gene) Finger-1 (MuRF-1). We found that hindlimb unloading induced a significant increase in XO activity and in the protein expression of the antioxidant enzymes CuZnSOD and Catalase in skeletal muscle. The most relevant new fact reported in this paper is that inhibition of XO with allopurinol, a drug widely used in clinical practice, prevents soleus muscle atrophy by ~20% after hindlimb unloading. This was associated with the inhibition of the p38 MAPK-MAFbx pathway. Our data suggest that XO was involved in the loss of muscle mass via the activation of the p38MAPK-MAFbx pathway in unloaded muscle atrophy. Thus, allopurinol may have clinical benefits to combat skeletal muscle atrophy in bedridden, astronauts, sarcopenic, and cachexic patients.

Topics: Allopurinol; Animals; Enzyme Activation; Hindlimb Suspension; Male; Muscle Proteins; Muscle, Skeletal; Muscular Atrophy; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Rats; Rats, Wistar; SKP Cullin F-Box Protein Ligases; Superoxide Dismutase; Tripartite Motif Proteins; Ubiquitin-Protein Ligases; Xanthine Oxidase

Respiratory muscle weakness resulting from both diaphragmatic contractile dysfunction and atrophy has been hypothesized to contribute to the weaning difficulties associated with prolonged mechanical ventilation (MV). While it is clear that oxidative injury contributes to MV-induced diaphragmatic weakness, the source(s) of oxidants in the diaphragm during MV remain unknown. These experiments tested the hypothesis that xanthine oxidase (XO) contributes to MV-induced oxidant production in the rat diaphragm and that oxypurinol, a XO inhibitor, would attenuate MV-induced diaphragmatic oxidative stress, contractile dysfunction, and atrophy. Adult female Sprague-Dawley rats were randomly assigned to one of six experimental groups: 1) control, 2) control with oxypurinol, 3) 12 h of MV, 4) 12 h of MV with oxypurinol, 5) 18 h of MV, or 6) 18 h of MV with oxypurinol. XO activity was significantly elevated in the diaphragm after MV, and oxypurinol administration inhibited this activity and provided protection against MV-induced oxidative stress and contractile dysfunction. Specifically, oxypurinol treatment partially attenuated both protein oxidation and lipid peroxidation in the diaphragm during MV. Further, XO inhibition retarded MV-induced diaphragmatic contractile dysfunction at stimulation frequencies >60 Hz. Collectively, these results suggest that oxidant production by XO contributes to MV-induced oxidative injury and contractile dysfunction in the diaphragm. Nonetheless, the failure of XO inhibition to completely prevent MV-induced diaphragmatic oxidative damage suggests that other sources of oxidant production are active in the diaphragm during prolonged MV.

Topics: Animals; Diaphragm; Disease Models, Animal; Electric Stimulation; Enzyme Inhibitors; Female; Hypoxanthine; Lipid Peroxidation; Muscle Contraction; Muscle Weakness; Muscular Atrophy; Oxidative Stress; Oxypurinol; Protein Carbonylation; Rats; Rats, Sprague-Dawley; Time Factors; Uric Acid; Ventilator-Induced Lung Injury; Xanthine; Xanthine Dehydrogenase; Xanthine Oxidase

Topics: Animals; Antioxidants; Critical Illness; Diaphragm; Enzyme Inhibitors; Humans; Muscle Contraction; Muscle Weakness; Muscular Atrophy; Oxidative Stress; Ventilator-Induced Lung Injury; Xanthine Dehydrogenase; Xanthine Oxidase

Muscle atrophy with aging or disuse is associated with deregulated iron homeostasis and increased oxidative stress likely inflicting damage to nucleic acids. Therefore, we investigated RNA and DNA oxidation, and iron homeostasis in gastrocnemius muscles. Disuse atrophy was induced in 6- and 32-month old male Fischer 344/Brown Norway rats by 14 days of hind limb suspension (HS). We show that RNA, but not DNA, oxidative damage increased 85% with age and 36% with HS in aged muscle. Additionally, non-heme iron levels increased 233% with aging and 83% with HS at old age, while staining for free iron was strongest in the smallest fibers. Simultaneously, the mRNA abundance of transferrin receptor-1 decreased by 80% with age and 48% with HS for young animals, while that of the hepcidin regulator hemojuvelin decreased 37% with age, but increased about 44% with disuse, indicating a dysregulation of iron homeostasis favoring increased intracellular free iron in atrophied muscles. RNA and DNA concentrations increased with age and were negatively correlated with muscle mass, whereas protein concentrations decreased with aging, indicating a preferential loss of protein compared to nucleic acids. Furthermore, xanthine oxidase activity increased with age, but not with HS, while mRNA abundance of the Y box-binding protein-1, which has been suggested to bind oxidized RNA, did not change with age or HS. These results suggest that RNA oxidation, possibly mediated by increased non-heme iron, might contribute to muscle atrophy due to disuse particularly in aged muscle.

Topics: Aging; Animals; Biomarkers; Chromatography, High Pressure Liquid; DNA; Hindlimb; Hindlimb Suspension; Homeostasis; Iron; Male; Models, Animal; Muscle, Skeletal; Muscular Atrophy; Muscular Disorders, Atrophic; Oxidative Stress; Peroxidase; Polymerase Chain Reaction; Rats; Rats, Inbred BN; RNA; Xanthine Oxidase

Prolonged mechanical unloading induces skeletal muscle weakness, a major problem following extended bed rest or spaceflight. Antioxidants are reported to partially inhibit the weakness caused by limb immobilization. The current study tested allopurinol, a xanthine oxidase inhibitor with antioxidant properties, for its capacity to protect the function of unloaded antigravity muscles.. Adult mice conditioned by 12 d of hindlimb suspension, with or without allopurinol 50 mg x kg(-1) x d(-1), were compared with freely ambulating controls. Animals were anesthetized and soleus muscles were isolated for ex vivo analyses.. Relative to control muscles, unloading decreased soleus weight (-44%; p < 0.05) and cross-sectional area (-38%; p < 0.05), increased cytosolic oxidant activity (-46%; p < 0.01), decreased absolute tetanic force (e.g., -64% at 250 Hz; p < 0.001 ) and force/area (-35%; p < 0.01), and increased passive compliance of the unstimulated muscle (p < 0.05). Allopurinol administration blunted the effects of unloading, partially inhibiting losses of absolute force (p < 0.05) and force/area (p < 0.05) without affecting muscle atrophy. The drug also blunted compliance changes in the passive muscle (p < 0.05).. Allopurinol does not inhibit atrophy of skeletal muscle caused by prolonged unloading. However, allopurinol does lessen the contractile dysfunction caused by unloading, an action that may have potential benefit for astronauts and bedridden individuals.

Topics: Allopurinol; Animals; Antioxidants; Enzyme Inhibitors; Free Radical Scavengers; Hindlimb Suspension; Male; Mice; Mice, Inbred ICR; Muscle Contraction; Muscle, Skeletal; Muscular Atrophy; Xanthine Oxidase

Topics: Adolescent; Adult; Allopurinol; Electromyography; Fatigue; Female; Humans; Kidney; Kidney Failure, Chronic; Knee; Male; Median Nerve; Methods; Middle Aged; Muscle Contraction; Muscle Denervation; Muscles; Muscular Atrophy; Muscular Diseases; Neural Conduction; Neurologic Manifestations; Tracheotomy; Uremia