Effect of Novel Antipsychotics on Energy Metabolism - In Vitro Study in Pig Brain Mitochondria.

The identification and quantification of mitochondrial effects of novel antipsychotics (brexpiprazole, cariprazine, loxapine, and lurasidone) were studied in vitro in pig brain mitochondria. Selected parameters of mitochondrial metabolism, electron transport chain (ETC) complexes, citrate synthase (CS), malate dehydrogenase (MDH), monoamine oxidase (MAO), mitochondrial respiration, and total ATP and reactive oxygen species (ROS) production were evaluated and associated with possible adverse effects of drugs. All tested antipsychotics decreased the ETC activities (except for complex IV, which increased in activity after brexpiprazole and loxapine addition). Both complex I- and complex II-linked respiration were dose-dependently inhibited, and significant correlations were found between complex I-linked respiration and both complex I activity (positive correlation) and complex IV activity (negative correlation). All drugs significantly decreased mitochondrial ATP production at higher concentrations. Hydrogen peroxide production was significantly increased at 10 µM brexpiprazole and lurasidone and at 100 µM cariprazine and loxapine. All antipsychotics acted as partial inhibitors of MAO-A, brexpiprazole and loxapine partially inhibited MAO-B. Based on our results, novel antipsychotics probably lacked oxygen uncoupling properties. The mitochondrial effects of novel antipsychotics might contribute on their adverse effects, which are mostly related to decreased ATP production and increased ROS production, while MAO-A inhibition might contribute to their antidepressant effect, and brexpiprazole- and loxapine-induced MAO-B inhibition might likely promote neuroplasticity and neuroprotection. The assessment of drug-induced mitochondrial dysfunctions is important in development of new drugs as well as in the understanding of molecular mechanism of adverse or side drug effects.

Bromodomain-containing protein 4 inhibitor JQ1 promotes melanoma cell apoptosis by regulating mitochondrial dynamics.

Although the role of bromodomain-containing protein 4 (BRD4) in ovarian cancer, pancreatic cancer, lymphoma, and many other diseases is well known, its function in cutaneous melanoma is only partially understood. The results of the present study show that the BRD4 inhibitor JQ1 promotes the apoptosis of B16 melanoma cells by altering mitochondrial dynamics, thereby inducing mitochondrial dysfunction and increasing oxidative stress. We found that treatment of B16 cells with different concentrations of JQ1 (125 nmol/L or 250 nmol/L) significantly downregulated the expression of protein subunits involved in mitochondrial respiratory chain complexes I, III, IV, and V, increased reactive oxygen species, induced energy metabolism dysfunction, significantly enhanced apoptosis, and activated the mitochondrial apoptosis pathway. At the same time, JQ1 inhibited the activation of AMP-activated protein kinase, a metabolic energy sensor. In addition, we found that the mRNA and protein levels of mitochondrial dynamin-related protein 1 increased, whereas the levels of mitochondrial fusion protein 1 and optic atrophy protein 1 decreased. Mechanistically, we determined that JQ1 inhibited the expression of c-Myc and altered mitochondrial dynamics, eventually leading to changes in the mitochondrial function, metabolism, and apoptosis of B16 melanoma cells.

Downregulation of the tyrosine degradation pathway extends Drosophila lifespan.

Aging is characterized by extensive metabolic reprogramming. To identify metabolic pathways associated with aging, we analyzed age-dependent changes in the metabolomes of long-lived Drosophila melanogaster. Among the metabolites that changed, levels of tyrosine were increased with age in long-lived flies. We demonstrate that the levels of enzymes in the tyrosine degradation pathway increase with age in wild-type flies. Whole-body and neuronal-specific downregulation of enzymes in the tyrosine degradation pathway significantly extends Drosophila lifespan, causes alterations of metabolites associated with increased lifespan, and upregulates the levels of tyrosine-derived neuromediators. Moreover, feeding wild-type flies with tyrosine increased their lifespan. Mechanistically, we show that suppression of ETC complex I drives the upregulation of enzymes in the tyrosine degradation pathway, an effect that can be rescued by tigecycline, an FDA-approved drug that specifically suppresses mitochondrial translation. In addition, tyrosine supplementation partially rescued lifespan of flies with ETC complex I suppression. Altogether, our study highlights the tyrosine degradation pathway as a regulator of longevity.

Multiwalled carbon nanotubes inhibit cell migration and invasion by destroying actin cytoskeleton via mitochondrial dysfunction in ovarian cancer cells.

OBJECTIVE: This study aimed to investigate the effects of multiwalled carbon nanotubes (MWCNTs) on cytotoxicity and tumor metastasis in ovarian cancer cells, and further explored its mechanism. RESULTS: MWCNTs significantly inhibited cell viability and the clone number, increased the cell number of S phage, promoted cell apoptosis, as well as suppressed cell migration and invasion, and damaged the structure of actin cytoskeleton in a dose-dependent manner in SKOV3. Moreover, MWCNTs treatment obviously damaged the structure of actin cytoskeleton of SKOV3, and inhibited the activities of mitochondrial electron transfer chain complexes I-V. CONCLUSIONS: MWCNTs might influence the assembly of actin cytoskeleton by disrupting mitochondrial function, thereby inhibiting migration and invasion of SKOV3. METHODS: The characterization of MWCNTs was analyzed by UV visible light absorption spectroscopy and transmission electron microscopy. SKOV3 cells were exposed to different doses of MWCNTs. Then, in vitro cytotoxicity of MWCNTs was evaluated by MTT assay, colony-forming assay, cell cycle, and cell apoptosis assay. Moreover, the effects of MWCNTs on cell migration and invasion as well as actin cytoskeleton were explored in SKOV3 cells. Furthermore, the mitochondrial membrane potential and the activities of mitochondrial electron transfer chain complexes I-V were measured.

Mitocans Revisited: Mitochondrial Targeting as Efficient Anti-Cancer Therapy.

Mitochondria are essential cellular organelles, controlling multiple signalling pathways critical for cell survival and cell death. Increasing evidence suggests that mitochondrial metabolism and functions are indispensable in tumorigenesis and cancer progression, rendering mitochondria and mitochondrial functions as plausible targets for anti-cancer therapeutics. In this review, we summarised the major strategies of selective targeting of mitochondria and their functions to combat cancer, including targeting mitochondrial metabolism, the electron transport chain and tricarboxylic acid cycle, mitochondrial redox signalling pathways, and ROS homeostasis. We highlight that delivering anti-cancer drugs into mitochondria exhibits enormous potential for future cancer therapeutic strategies, with a great advantage of potentially overcoming drug resistance. Mitocans, exemplified by mitochondrially targeted vitamin E succinate and tamoxifen (MitoTam), selectively target cancer cell mitochondria and efficiently kill multiple types of cancer cells by disrupting mitochondrial function, with MitoTam currently undergoing a clinical trial.

Bioenergetic and proteomic profiling to screen small molecule inhibitors that target cancer metabolisms.

Cancer cells can reprogram their metabolic machinery to survive. This altered metabolism, which is distinct from the metabolism of normal cells, is thought to be a possible target for the development of new cancer therapies. In this study, we constructed a screening system that focuses on bioenergetic profiles (specifically oxygen consumption rate and extracellular acidification rate) and characteristic proteomic changes. Thus, small molecules that target cancer-specific metabolism were investigated. We screened the chemical library of RIKEN Natural Products Depository (NPDepo) and found that unantimycin A, which was recently isolated from the fraction library of microbial metabolites, and NPL40330, which is derived from a chemical library, inhibit mitochondrial respiration. Furthermore, we developed an in vitro reconstitution assay method for mitochondrial electron transport chain using semi-intact cells with specific substrates for each complex of the mitochondrial electron transport chain. Our findings revealed that NPL40330 and unantimycin A target mitochondrial complexes I and III, respectively.

Discovery of novel arylethenesulfonyl fluorides as potential candidates against methicillin-resistant of Staphylococcus aureus (MRSA) for overcoming multidrug resistance of bacterial infections.

The multidrug-resistant Staphylococcus aureus (MRSA) is one of the most prevalent human pathogens involved in many minor to major disease burdens throughout the world. Inhibition of biofilm formation is an attractive strategy to treat diseases associated with MRSA infection. In the present investigation, a series of functional group diverse (hetero)aryl fluorosulfonyl analogs were designed, synthesized and tested as antibacterial agents against Staphylococcal spp., and as anti-biofilm candidates. Compounds 8, 15, and 67 were found to possess potent in vitro antibacterial activity among this class of sulfonyl fluorides (MIC = 0.818 ±â€¯0.42, 0.840 ±â€¯0.37 and 0.811 ±â€¯0.37 µg/mL respectively). The analogs 8, 15, 36, and 67 exhibited outstanding anti-biofilm properties compared to other available synthetic antibiotics. The efficacy of synthetic analogs displayed membrane-damaging effect and they are also validated by cellular content release assay. The insight physiological changes were explored by studying the intracellular redox activities through changing cyclic voltammetric (CV) method. The compounds 8, 15, 22, 32, 36, 51, and 67 were found to participate in the interfering in the electron transport chain (ETC) of MRSA. The analogs 8, 15, and 67 possess great potentiality for discovery and development of anti-staphylococcal drugs to treat the MRSA infections.

Combinations of Respiratory Chain Inhibitors Have Enhanced Bactericidal Activity against Mycobacterium tuberculosis.

As an obligate aerobe, Mycobacterium tuberculosis uses its electron transport chain (ETC) to produce energy via oxidative phosphorylation. This pathway has recently garnered a lot of attention and is a target for several new antimycobacterials. We tested the respiratory adaptation of M. tuberculosis to phenoxyalkylbenzimidazoles (PABs), compounds proposed to target QcrB, a component of the cytochrome bc1 complex. We show that M. tuberculosis is able to reroute its ETC to provide temporary resistance to PABs. However, combination treatment of PAB with agents targeting other components of the electron transport chain overcomes this respiratory flexibility. PAB in combination with clofazimine resulted in synergistic killing of M. tuberculosis under both replicating and nonreplicating conditions. PABs in combination with bedaquiline demonstrated antagonism at early time points, particularly under nonreplicating conditions. However, this antagonistic effect disappeared within 3 weeks, when PAB-BDQ combinations became highly bactericidal; in some cases, they were better than either drug alone. This study highlights the potential for combination treatment targeting the ETC and supports the development of PABs as part of a novel drug regimen against M. tuberculosis.

Lifelong quercetin enrichment and cardioprotection in Mdx/Utrn+/- mice.

Duchenne Muscular Dystrophy (DMD) is associated with progressive cardiac pathology; however, the SIRT1/PGC1-α activator quercetin may cardioprotect dystrophic hearts. We tested the extent to which long-term 0.2% dietary quercetin enrichment attenuates dystrophic cardiopathology in Mdx/Utrn+/- mice. At 2 mo, Mdx/Utrn+/- mice were fed quercetin-enriched (Mdx/Utrn+/--Q) or control diet (Mdx/Utrn+/-) for 8 mo. Control C57BL/10 (C57) animals were fed a control diet for 10 mo. Cardiac function was quantified by MRI at 2 and 10 mo. Spontaneous physical activity was quantified during the last week of treatment. At 10 mo hearts were excised for histological and biochemical analysis. Quercetin feeding improved various physiological indexes of cardiac function in diseased animals. Mdx/Utrn+/--Q also engaged in more high-intensity physical activity than controls. Histological analyses of heart tissues revealed higher expression and colocalization of utrophin and α-sarcoglycan. Lower abundance of fibronectin, cardiac damage (Hematoxylin Eosin-Y), and MMP9 were observed in quercetin-fed vs. control Mdx/Utrn+/- mice. Quercetin evoked higher protein abundance of PGC-1α, cytochrome c, ETC complexes I-V, citrate synthase, SOD2, and GPX compared with control-fed Mdx/Utrn+/- Quercetin decreased abundance of inflammatory markers including NFκB, TGF-ß1, and F4/80 compared with Mdx/Utrn+/-; however, P-NFκB, P-IKBα, IKBα, CD64, and COX2 were similar between groups. Dietary quercetin enrichment improves cardiac function in aged Mdx/Utrn+/- mice and increases mitochondrial protein content and dystrophin glycoprotein complex formation. Histological analyses indicate a marked attenuation in pathological cardiac remodeling and indicate that long-term quercetin consumption benefits the dystrophic heart. NEW & NOTEWORTHY: The current investigation provides first-time evidence that quercetin provides physiological cardioprotection against dystrophic pathology and is associated with improved spontaneous physical activity. Secondary findings suggest that quercetin-dependent outcomes are in part due to PGC-1α pathway activation.

A Biophysical Systems Approach to Identifying the Pathways of Acute and Chronic Doxorubicin Mitochondrial Cardiotoxicity.

The clinical use of the anthracycline doxorubicin is limited by its cardiotoxicity which is associated with mitochondrial dysfunction. Redox cycling, mitochondrial DNA damage and electron transport chain inhibition have been identified as potential mechanisms of toxicity. However, the relative roles of each of these proposed mechanisms are still not fully understood. The purpose of this study is to identify which of these pathways independently or in combination are responsible for doxorubicin toxicity. A state of the art mathematical model of the mitochondria including the citric acid cycle, electron transport chain and ROS production and scavenging systems was extended by incorporating a novel representation for mitochondrial DNA damage and repair. In silico experiments were performed to quantify the contributions of each of the toxicity mechanisms to mitochondrial dysfunction during the acute and chronic stages of toxicity. Simulations predict that redox cycling has a minor role in doxorubicin cardiotoxicity. Electron transport chain inhibition is the main pathway for acute toxicity for supratherapeutic doses, being lethal at mitochondrial concentrations higher than 200µM. Direct mitochondrial DNA damage is the principal pathway of chronic cardiotoxicity for therapeutic doses, leading to a progressive and irreversible long term mitochondrial dysfunction.

Mitochondrial Dysfunction in the Liver and Antiphospholipid Antibody Production Precede Disease Onset and Respond to Rapamycin in Lupus-Prone Mice.

OBJECTIVE: Antiphospholipid antibodies (aPL) constitute a diagnostic criterion of systemic lupus erythematosus (SLE), and aPL have been functionally linked to liver disease in patients with SLE. Since the mechanistic target of rapamycin (mTOR) is a regulator of oxidative stress, a pathophysiologic process that contributes to the development of aPL, this study was undertaken in a mouse model of SLE to examine the involvement of liver mitochondria in lupus pathogenesis. METHODS: Mitochondria were isolated from lupus-prone MRL/lpr, C57BL/6.lpr, and MRL mice, age-matched autoimmunity-resistant C57BL/6 mice as negative controls, and transaldolase-deficient mice, a strain that exhibits oxidative stress in the liver. Electron transport chain (ETC) activity was assessed using measurements of oxygen consumption. ETC proteins, which are regulators of mitochondrial homeostasis, and the mTOR complexes mTORC1 and mTORC2 were examined by Western blotting. Anticardiolipin (aCL) and anti-ß2 -glycoprotein I (anti-ß2 GPI) autoantibodies were measured by enzyme-linked immunosorbent assay in mice treated with rapamycin or mice treated with a solvent control. RESULTS: Mitochondrial oxygen consumption was increased in the livers of 4-week-old, disease-free MRL/lpr mice relative to age-matched controls. Levels of the mitophagy initiator dynamin-related protein 1 (Drp1) were depleted while the activity of mTORC1 was increased in MRL/lpr mice. In turn, mTORC2 activity was decreased in MRL and MRL/lpr mice. In addition, levels of aCL and anti-ß2 GPI were elevated preceding the development of nephritis in 4-week-old MRL, C57BL/6.lpr, and MRL/lpr mice. Transaldolase-deficient mice showed increased oxygen consumption, depletion of Drp1, activation of mTORC1, and elevated expression of NADH:ubiquinone oxidoreductase core subunit S3 (NDUFS3), a pro-oxidant subunit of ETC complex I, as well as increased production of aCL and anti-ß2 GPI autoantibodies. Treatment with rapamycin selectively blocked mTORC1 activation, NDUFS3 expression, and aPL production both in transaldolase-deficient mice and in lupus-prone mice. CONCLUSION: In lupus-prone mice, mTORC1-dependent mitochondrial dysfunction contributes to the generation of aPL, suggesting that such mechanisms may represent a treatment target in patients with SLE.

The purine analogues abacavir and didanosine increase acetaminophen-induced hepatotoxicity by enhancing mitochondrial dysfunction.

BACKGROUND: NRTIs are essential components of HIV therapy with well-documented, long-term mitochondrial toxicity in hepatic cells, but whose acute effects on mitochondria are unclear. As acetaminophen-induced hepatotoxicity also involves mitochondrial interference, we hypothesized that it would be exacerbated in the context of ART. METHODS: We evaluated the acute effects of clinically relevant concentrations of the most widely used NRTIs, alone or combined with acetaminophen, on mitochondrial function and cellular viability. RESULTS: The purine analogues abacavir and didanosine produced an immediate and concentration-dependent inhibition of oxygen consumption and complex I and III activity. This inhibition was accompanied by an undermining of mitochondrial function, with increased production of reactive oxygen species and reduction of mitochondrial membrane potential and intracellular ATP levels. However, this interference did not compromise cell survival. Co-administration with concentrations of acetaminophen below those considered hepatotoxic exacerbated the deleterious effects of both compounds on mitochondrial function and compromised cellular viability, showing a clear correlation with diminished glutathione levels. CONCLUSIONS: The simultaneous presence of purine analogues and low concentrations of acetaminophen significantly potentiates mitochondrial dysfunction, increasing the risk of liver injury. This new mechanism is relevant given the liver's susceptibility to mitochondrial dysfunction-related toxicity and the tendency of the HIV infection to increase oxidative stress.

Severe Hyperhomocysteinemia Decreases Respiratory Enzyme and Na(+)-K(+) ATPase Activities, and Leads to Mitochondrial Alterations in Rat Amygdala.

Severe hyperhomocysteinemia is caused by increased plasma levels of homocysteine (Hcy), a methionine derivative, and is associated with cerebral disorders. Creatine supplementation has emerged as an adjuvant to protect against neurodegenerative diseases, due to its potential antioxidant role. Here, we examined the effects of severe hyperhomocysteinemia on brain metabolism, and evaluated a possible neuroprotective role of creatine in hyperhomocysteinemia, by concomitant treatment with Hcy and creatine (50 mg/Kg body weight). Hyperhomocysteinemia was induced in young rats (6-day-old) by treatment with homocysteine (0.3-0.6 µmol/g body weight) for 23 days, and then the following parameters of rat amygdala were evaluated: (1) the activity of the respiratory chain complexes succinate dehydrogenase, complex II and cytochrome c oxidase; (2) mitochondrial mass and membrane potential; (3) the levels of necrosis and apoptosis; and (4) the activity and immunocontent of Na(+),K(+)-ATPase. Hcy treatment decreased the activities of succinate dehydrogenase and cytochrome c oxidase, but did not alter complex II activity. Hcy treatment also increased the number of cells with high mitochondrial mass, high mitochondrial membrane potential, and in late apoptosis. Importantly, creatine administration prevented some of the key effects of Hcy administration on the amygdala. We also observed a decrease in the activity and immunocontent of the α1 subunit of the Na(+),K(+)-ATPase in amygdala after Hcy- treatment. Our findings support the notion that Hcy modulates mitochondrial function and bioenergetics in the brain, as well as Na(+),K(+)-ATPase activity, and suggest that creatine might represent an effective adjuvant to protect against the effects of high Hcy plasma levels.

The characterization of neuroenergetic effects of chronic L-tyrosine administration in young rats: evidence for striatal susceptibility.

Tyrosinemia type II is an inborn error of metabolism caused by a deficiency in hepatic cytosolic aminotransferase. Affected patients usually present a variable degree of mental retardation, which may be related to the level of plasma tyrosine. In the present study we evaluated effect of chronic administration of L-tyrosine on the activities of citrate synthase, malate dehydrogenase, succinate dehydrogenase and complexes I, II, II-III and IV in cerebral cortex, hippocampus and striatum of rats in development. Chronic administration consisted of L-tyrosine (500 mg/kg) or saline injections 12 h apart for 24 days in Wistar rats (7 days old); rats were killed 12 h after last injection. Our results demonstrated that L-tyrosine inhibited the activity of citrate synthase in the hippocampus and striatum, malate dehydrogenase activity was increased in striatum and succinate dehydrogenase, complexes I and II-III activities were inhibited in striatum. However, complex IV activity was increased in hippocampus and inhibited in striatum. By these findings, we suggest that repeated administrations of L-tyrosine cause alterations in energy metabolism, which may be similar to the acute administration in brain of infant rats. Taking together the present findings and evidence from the literature, we hypothesize that energy metabolism impairment could be considered an important pathophysiological mechanism underlying the brain damage observed in patients with tyrosinemia type II.

Measuring interference of drug-like molecules with the respiratory chain: toward the early identification of mitochondrial uncouplers in lead finding.

The electron transport chain (ETC) couples electron transfer between donors and acceptors with proton transport across the inner mitochondrial membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate (ATP). Proton transfer is based on the activity of complex I-V proteins in the ETC. The overall electrical activity of these proteins can be measured by proton transfer using Solid Supported Membrane technology. We tested the activity of complexes I, III, and V in a combined assay, called oxidative phosphorylation assay (oxphos assay), by activating each complex with the corresponding substrate. The oxphos assay was used to test in-house substances from different projects and several drugs currently available on the market that have reported effects on mitochondrial functions. The resulting data were compared to the influence of the respective compounds on mitochondria as determined by oxygen consumption and to data generated with an ATP depletion assay. The comparison shows that the oxidative phosphorylation assay provides both a rapid approach for detecting interaction of compounds with respiratory chain proteins and information on their mode of interaction. Therefore, the oxphos assay is a useful tool to support structure activity relationship studies by allowing early identification of mitotoxicity and for analyzing the outcome of phenotypic screens that are susceptible to the generation of mitotoxicity-related artifacts.

Integrated compound profiling screens identify the mitochondrial electron transport chain as the molecular target of the natural products manassantin, sesquicillin, and arctigenin.

Phenotypic compound screens can be used to identify novel targets in signaling pathways and disease processes, but the usefulness of these screens depends on the ability to quickly determine the target and mechanism of action of the molecules identified as hits. One fast route to discovering the mechanism of action of a compound is to profile its properties and to match this profile with those of compounds of known mechanism of action. In this work, the Novartis collection of over 12,000 pure natural products was screened for effects on early zebrafish development. The largest phenotypic class of hits, which caused developmental arrest without necrosis, contained known electron transport chain inhibitors and many compounds of unknown mechanism of action. High-throughput transcriptional profiling revealed that these compounds are mechanistically related to one another. Metabolic and biochemical assays confirmed that all of the molecules that induced developmental arrest without necrosis inhibited the electron transport chain. These experiments demonstrate that the electron transport chain is the target of the natural products manassantin, sesquicillin, and arctigenin. The overlap between the zebrafish and transcriptional profiling screens was not perfect, indicating that multiple profiling screens are necessary to fully characterize molecules of unknown function. Together, zebrafish screening and transcriptional profiling represent sensitive and scalable approaches for identifying bioactive compounds and elucidating their mechanism of action.

Opposing effects of nitric oxide and prostaglandin inhibition on muscle mitochondrial Vo(2) during exercise.

Nitric oxide (NO) and prostaglandins (PG) together play a role in regulating blood flow during exercise. NO also regulates mitochondrial oxygen consumption through competitive binding to cytochrome-c oxidase. Indomethacin uncouples and inhibits the electron transport chain in a concentration-dependent manner, and thus, inhibition of NO and PG synthesis may regulate both muscle oxygen delivery and utilization. The purpose of this study was to examine the independent and combined effects of NO and PG synthesis blockade (L-NMMA and indomethacin, respectively) on mitochondrial respiration in human muscle following knee extension exercise (KEE). Specifically, this study examined the physiological effect of NO, and the pharmacological effect of indomethacin, on muscle mitochondrial function. Consistent with their mechanism of action, we hypothesized that inhibition of nitric oxide synthase (NOS) and PG synthesis would have opposite effects on muscle mitochondrial respiration. Mitochondrial respiration was measured ex vivo by high-resolution respirometry in saponin-permeabilized fibers following 6 min KEE in control (CON; n = 8), arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA; n = 4) and Indo (n = 4) followed by combined inhibition of NOS and PG synthesis (L-NMMA + Indo, n = 8). ADP-stimulated state 3 respiration (OXPHOS) with substrates for complex I (glutamate, malate) was reduced 50% by Indo. State 3 O(2) flux with complex I and II substrates was reduced less with both Indo (20%) and L-NMMA + Indo (15%) compared with CON. The results indicate that indomethacin reduces state 3 mitochondrial respiration primarily at complex I of the respiratory chain, while blockade of NOS by L-NMMA counteracts the inhibition by Indo. This effect on muscle mitochondria, in concert with a reduction of blood flow accounts for in vivo changes in muscle O(2) consumption during combined blockade of NOS and PG synthesis.

Behavioral improvement after chronic administration of coenzyme Q10 in P301S transgenic mice.

Coenzyme Q10 is a key component of the electron transport chain which plays an essential role in ATP production and also has antioxidant effects. Neuroprotective effects of coenzyme Q10 have been reported in both in vitro and in vivo models of neurodegenerative diseases. However, its effects have not been studied in cells or in animals with tau induced pathology. In this report, we administered coenzyme Q10 to transgenic mice with the P301S tau mutation, which causes fronto-temporal dementia in man. These mice develop tau hyperphosphorylation and neurofibrillary tangles in the brain. Coenzyme Q10 improved survival and behavioral deficits in the P301S mice. There was a modest reduction in phosphorylated tau in the cortex of P301S mice. We also examined the effects of coenzyme Q10 treatment on the electron transport chain enzymes, the mitochondrial antioxidant enzymes, and the tricarboxylic acid cycle. There was a significant increase in complex I activity and protein levels, and a reduction in lipid peroxidation. Our data show that coenzyme Q10 significantly improved behavioral deficits and survival in transgenic mice with the P301S tau mutation, upregulated key enzymes of the electron transport chain, and reduced oxidative stress.