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Azevedo RDSD, Falcão KVG, Almeida SMVD, Araújo MC, Silva-Filho RC, Souza Maia MBD, Amaral IPGD, Leite ACR, de Souza Bezerra R. The tissue-specific nature of physiological zebrafish mitochondrial bioenergetics. Mitochondrion 2024; 77:101901. [PMID: 38777222 DOI: 10.1016/j.mito.2024.101901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 04/27/2024] [Accepted: 05/15/2024] [Indexed: 05/25/2024]
Abstract
Zebrafish are a powerful tool to study a myriad of experimental conditions, including mitochondrial bioenergetics. Considering that mitochondria are different in many aspects depending on the tissue evaluated, in the zebrafish model there is still a lack of this investigation. Especially for juvenile zebrafish. In the present study, we examined whether different tissues from zebrafish juveniles show mitochondrial density- and tissue-specificity comparing brain, liver, heart, and skeletal muscle (SM). The liver and brain complex IV showed the highest O2 consumption of all ETC in all tissues (10x when compared to other respiratory complexes). The liver showed a higher potential for ROS generation. In this way, the brain and liver showed more susceptibility to O2- generation when compared to other tissues. Regarding Ca2+ transport, the brain showed greater capacity for Ca2+ uptake and the liver presented low Ca2+ uptake capacity. The liver and brain were more susceptible to producing NO. The enzymes SOD and Catalase showed high activity in the brain, whereas GPx showed higher activity in the liver and CS in the SM. TEM reveals, as expected, a physiological diverse mitochondrial morphology. The essential differences between zebrafish tissues investigated probably reflect how the mitochondria play a diverse role in systemic homeostasis. This feature may not be limited to normal metabolic functions but also to stress conditions. In summary, mitochondrial bioenergetics in zebrafish juvenile permeabilized tissues showed a tissue-specificity and a useful tool to investigate conditions of redox system imbalance, mainly in the liver and brain.
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Affiliation(s)
- Rafael David Souto de Azevedo
- Laboratório de Biologia Celular e Molecular, Universidade de Pernambuco - UPE, Campus Garanhuns, Garanhuns, PE, Brazil.
| | - Kivia Vanessa Gomes Falcão
- Departamento de Bioquímica, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE, Brazil
| | | | - Marlyete Chagas Araújo
- Departamento de Bioquímica, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE, Brazil
| | | | | | | | | | - Ranilson de Souza Bezerra
- Departamento de Bioquímica, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE, Brazil
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Pan J, Pany S, Martinez-Carrasco R, Fini ME. Differential Efficacy of Small Molecules Dynasore and Mdivi-1 for the Treatment of Dry Eye Epitheliopathy or as a Countermeasure for Nitrogen Mustard Exposure of the Ocular Surface. J Pharmacol Exp Ther 2024; 388:506-517. [PMID: 37442618 PMCID: PMC10801785 DOI: 10.1124/jpet.123.001697] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/19/2023] [Accepted: 06/05/2023] [Indexed: 07/15/2023] Open
Abstract
The ocular surface comprises the wet mucosal epithelia of the cornea and conjunctiva, the associated glands, and the overlying tear film. Epitheliopathy is the common pathologic outcome when the ocular surface is subjected to oxidative stress. Whether different stresses act via the same or different mechanisms is not known. Dynasore and dyngo-4a, small molecules developed to inhibit the GTPase activity of classic dynamins DNM1, DNM2, and DNM3, but not mdivi-1, a specific inhibitor of DNM1L, protect corneal epithelial cells exposed to the oxidant tert-butyl hydroperoxide (tBHP). Here we report that, while dyngo-4a is the more potent inhibitor of endocytosis, dynasore is the better cytoprotectant. Dynasore also protects corneal epithelial cells against exposure to high salt in an in vitro model of dysfunctional tears in dry eye. We now validate this finding in vivo, demonstrating that dynasore protects against epitheliopathy in a mouse model of dry eye. Knockdown of classic dynamin DNM2 was also cytoprotective against tBHP exposure, suggesting that dynasore's effect is at least partially on target. Like tBHP and high salt, exposure of corneal epithelial cells to nitrogen mustard upregulated the unfolded protein response and inflammatory markers, but dynasore did not protect against nitrogen mustard exposure. In contrast, mdivi-1 was cytoprotective. Interestingly, mdivi-1 did not inhibit the nitrogen mustard-induced expression of inflammatory cytokines. We conclude that exposure to tBHP or nitrogen mustard, two different oxidative stress agents, cause corneal epitheliopathy via different pathologic pathways. SIGNIFICANCE STATEMENT: Results presented in this paper, for the first time, implicate the dynamin DNM2 in ocular surface epitheliopathy. The findings suggest that dynasore could serve as a new topical treatment for dry eye epitheliopathy and that mdivi-1 could serve as a medical countermeasure for epitheliopathy due to nitrogen mustard exposure, with potentially increased efficacy when combined with anti-inflammatory agents and/or UPR modulators.
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Affiliation(s)
- Jinhong Pan
- New England Eye Center, Tufts Medical Center and Department of Ophthalmology, Tufts University School of Medicine (J.P., S.P., R.M.-C., M.E.F.) and Program in Pharmacology and Drug Development, Tufts Graduate School of Biomedical Sciences (M.E.F.), Tufts University, Boston, Massachusetts
| | - Satyabrata Pany
- New England Eye Center, Tufts Medical Center and Department of Ophthalmology, Tufts University School of Medicine (J.P., S.P., R.M.-C., M.E.F.) and Program in Pharmacology and Drug Development, Tufts Graduate School of Biomedical Sciences (M.E.F.), Tufts University, Boston, Massachusetts
| | - Rafael Martinez-Carrasco
- New England Eye Center, Tufts Medical Center and Department of Ophthalmology, Tufts University School of Medicine (J.P., S.P., R.M.-C., M.E.F.) and Program in Pharmacology and Drug Development, Tufts Graduate School of Biomedical Sciences (M.E.F.), Tufts University, Boston, Massachusetts
| | - M Elizabeth Fini
- New England Eye Center, Tufts Medical Center and Department of Ophthalmology, Tufts University School of Medicine (J.P., S.P., R.M.-C., M.E.F.) and Program in Pharmacology and Drug Development, Tufts Graduate School of Biomedical Sciences (M.E.F.), Tufts University, Boston, Massachusetts
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3
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Yang Y, Zhang Y, Yang C, Fang F, Wang Y, Chang H, Chen Z, Chen P. Differential mitochondrial proteomic analysis of A549 cells infected with avian influenza virus subtypes H5 and H9. Virol J 2021; 18:39. [PMID: 33602268 PMCID: PMC7891018 DOI: 10.1186/s12985-021-01512-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 02/08/2021] [Indexed: 01/14/2023] Open
Abstract
Background Both the highly pathogenic avian influenza (HPAI) H5N1 and low pathogenic avian influenza (LPAI) H9N2 viruses have been reported to cross species barriers to infect humans. H5N1 viruses can cause severe damage and are associated with a high mortality rate, but H9N2 viruses do not cause such outcomes. Our purpose was to use proteomics technology to study the differential expression of mitochondrial-related proteins related to H5N1 and H9N2 virus infections.
Methods According to the determined viral infection titer, A549 cells were infected with 1 multiplicity of infection virus, and the mitochondria were extracted after 24 h of incubation. The protein from lysed mitochondria was analyzed by the BCA method to determine the protein concentration, as well as SDS-PAGE (preliminary analysis), two-dimensional gel electrophoresis, and mass spectrometry. Differential protein spots were selected, and Western blotting was performed to verify the proteomics results. The identified proteins were subjected to GO analysis for subcellular localization, KEGG analysis for functional classification and signaling pathways assessment, and STRING analysis for functional protein association network construction. Results In the 2-D gel electrophoresis analysis, 227 protein spots were detected in the H5N1-infected group, and 169 protein spots were detected in the H9N2-infected group. Protein spots were further subjected to mass spectrometry identification and removal of redundancy, and 32 differentially expressed proteins were identified. Compared with the H9N2 group, the H5N1-infected group had 16 upregulated mitochondrial proteins and 16 downregulated proteins. The differential expression of 70-kDa heat shock protein analogs, short-chain enoyl-CoA hydratase, malate dehydrogenase, and ATP synthase was verified by Western blot, and the results were consistent with the proteomics findings. Functional analysis indicated that these differentially expressed proteins were primarily involved in apoptosis and metabolism. Conclusions Compared with their expression in the H9N2 group, the differential expression of eight mitochondrial proteins in the H5N1 group led to host T cell activation, antigen presentation, stress response, ATP synthesis and cell apoptosis reduction, leading to higher pathogenicity of H5N1 than H9N2. Supplementary Information The online version contains supplementary material available at 10.1186/s12985-021-01512-4.
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Affiliation(s)
- Yuting Yang
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China
| | - Yun Zhang
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China
| | - Changcheng Yang
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China
| | - Fang Fang
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China
| | - Ying Wang
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China
| | - Haiyan Chang
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China.
| | - Ze Chen
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China. .,Shanghai Institute of Biological Products, Shanghai, 200052, China.
| | - Ping Chen
- College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China.
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Herminghaus A, Buitenhuis AJ, Schulz J, Truse R, Vollmer C, Relja B, Bauer I, Picker O. Indomethacin Increases the Efficacy of Oxygen Utilization of Colonic Mitochondria and Uncouples Hepatic Mitochondria in Tissue Homogenates From Healthy Rats. Front Med (Lausanne) 2020; 7:463. [PMID: 32974368 PMCID: PMC7472952 DOI: 10.3389/fmed.2020.00463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/10/2020] [Indexed: 11/13/2022] Open
Affiliation(s)
- Anna Herminghaus
- Department of Anaesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
- *Correspondence: Anna Herminghaus
| | - Albert J. Buitenhuis
- Department of Anaesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Jan Schulz
- Department of Anaesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Richard Truse
- Department of Anaesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Christian Vollmer
- Department of Anaesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Borna Relja
- Experimental Radiology, Department of Radiology and Nuclear Medicine, Otto von Guericke University, Magdeburg, Germany
| | - Inge Bauer
- Department of Anaesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Olaf Picker
- Department of Anaesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
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5
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Soutar MPM, Kempthorne L, Annuario E, Luft C, Wray S, Ketteler R, Ludtmann MHR, Plun-Favreau H. FBS/BSA media concentration determines CCCP's ability to depolarize mitochondria and activate PINK1-PRKN mitophagy. Autophagy 2019; 15:2002-2011. [PMID: 31060423 PMCID: PMC6844515 DOI: 10.1080/15548627.2019.1603549] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 02/22/2019] [Accepted: 02/23/2019] [Indexed: 01/06/2023] Open
Abstract
Mitochondrial quality control is essential for maintaining a healthy population of mitochondria. Two proteins associated with Parkinson disease, the kinase PINK1 and the E3 ubiquitin ligase PRKN, play a central role in the selective degradation of heavily damaged mitochondria (mitophagy), thus avoiding their toxic accumulation. Most of the knowledge on PINK1-PRKN mitophagy comes from in vitro experiments involving the treatment of mammalian cells with high concentrations of mitochondrial uncouplers, such as CCCP. These chemicals have been shown to mediate off target effects, other than mitochondrial depolarization. A matter of controversy between mitochondrial physiologists and cell biologists is the discrepancy between concentrations of CCCP needed to activate mitophagy (usually >10 μM), when compared to the much lower concentrations used to depolarize mitochondria (<1 μM). Thus, there is an urgent need for optimizing the current methods to assess PINK1-PRKN mitophagy in vitro. In this study, we address the utilization of high CCCP concentrations commonly used to activate mitophagy. Combining live fluorescence microscopy and biochemistry, we show that the FBS/BSA in the cell culture medium reduces the ability of CCCP to induce PINK1 accumulation at depolarized mitochondria, subsequent PRKN recruitment and ubiquitin phosphorylation, and ultimately mitochondrial clearance. As a result, high concentrations of CCCP are required to induce mitophagy in FBS/BSA containing media. These data unite mitochondrial physiology and mitophagy studies and are a first step toward a consensus on optimal experimental conditions for PINK1-PRKN mitophagy and mitochondrial physiology investigations to be carried out in parallel. Abbreviations: BSA: bovine serum albumin; CCCP: carbonyl cyanide m-chlorophenylhydrazone; DMEM: dulbecco's Modified Eagle's Medium; DNP: 2,4-dinitrophenol; FBS: fetal bovine serum; FCCP: carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone; GSH: glutathione; HBSS: Hanks' balanced salt solution; mtKeima: mitochondria-targeted monomeric keima-red; PBS: phosphate buffered saline; PD: Parkinson disease; PINK1: PTEN induced kinase 1; POE SHSY5Ys: FLAG-PRKN over-expressing SHSY5Y cells; SDS-PAGE: sodium dodecyl sulfate polyacrylamide gel electrophoresis; TMRM: tetramethylrhodamine methyl ester; WB: western blot; WT: wild-type; ΔΨm: mitochondrial membrane potential.
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Affiliation(s)
| | - Liam Kempthorne
- Neurodegenerative Disease, UCL Institute of Neurology, London, UK
| | - Emily Annuario
- Neurodegenerative Disease, UCL Institute of Neurology, London, UK
| | - Christin Luft
- MRC Laboratory for Molecular Cell Biology, UCL, London, UK
| | - Selina Wray
- Neurodegenerative Disease, UCL Institute of Neurology, London, UK
| | - Robin Ketteler
- MRC Laboratory for Molecular Cell Biology, UCL, London, UK
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Komlódi T, Geibl FF, Sassani M, Ambrus A, Tretter L. Membrane potential and delta pH dependency of reverse electron transport-associated hydrogen peroxide production in brain and heart mitochondria. J Bioenerg Biomembr 2018; 50:355-365. [PMID: 30116920 PMCID: PMC6209044 DOI: 10.1007/s10863-018-9766-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/30/2018] [Indexed: 12/19/2022]
Abstract
Succinate-driven reverse electron transport (RET) is one of the main sources of mitochondrial reactive oxygen species (mtROS) in ischemia-reperfusion injury. RET is dependent on mitochondrial membrane potential (Δψm) and transmembrane pH difference (ΔpH), components of the proton motive force (pmf); a decrease in Δψm and/or ΔpH inhibits RET. In this study we aimed to determine which component of the pmf displays the more dominant effect on RET-provoked ROS generation in isolated guinea pig brain and heart mitochondria respiring on succinate or α-glycerophosphate (α-GP). Δψm was detected via safranin fluorescence and a TPP+ electrode, the rate of H2O2 formation was measured by Amplex UltraRed, the intramitochondrial pH (pHin) was assessed via BCECF fluorescence. Ionophores were used to dissect the effects of the two components of pmf. The K+/H+ exchanger, nigericin lowered pHin and ΔpH, followed by a compensatory increase in Δψm that led to an augmented H2O2 production. Valinomycin, a K+ ionophore, at low [K+] increased ΔpH and pHin, decreased Δψm, which resulted in a decline in H2O2 formation. It was concluded that Δψm is dominant over ∆pH in modulating the succinate- and α-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H2O2 release and a decreased ∆pH. This phenomenon reveals that from the pH component not ∆pH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of Δψm might be applied as a therapeutic strategy to attenuate RET-driven ROS generation in ischemia-reperfusion injury.
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Affiliation(s)
- Tímea Komlódi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary
| | - Fanni F Geibl
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary.,Department of Neurology, Philipps University Marburg, 35043, Marburg, Germany
| | - Matilde Sassani
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary.,Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary
| | - László Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tűzoltó St, Budapest, 1094, Hungary.
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7
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Lau GY, Richards JG. Interspecific variation in brain mitochondrial complex I and II capacity and ROS emission in marine sculpins. J Exp Biol 2018; 222:jeb.189407. [DOI: 10.1242/jeb.189407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 11/29/2018] [Indexed: 12/29/2022]
Abstract
Environmental hypoxia presents a metabolic challenge for animals because it inhibits mitochondrial respiration and can lead to the generation of reactive oxygen species (ROS). We investigated the interplay between O2 use for aerobic respiration and ROS generation among sculpin fishes (Cottidae, Actinopterygii) that are known to vary in whole-animal hypoxia tolerance. We hypothesized that mitochondria from hypoxia tolerant sculpins would show more efficient O2 use with a higher phosphorylation efficiency and lower ROS emission. We showed that brain mitochondria from more hypoxia tolerant sculpins had lower complex I and higher complex II flux capacities compared with less hypoxia tolerant sculpins, but these differences were not related to variation in phosphorylation efficiency (ADP/O) or mitochondrial coupling (respiratory control ratio). The hypoxia tolerant sculpin had higher mitochondrial H2O2 emission per O2 consumed (H2O2/O2) under oligomycin-induced state 4 conditions compared to less hypoxia tolerant sculpin. An in vitro redox challenge experiment revealed species differences in how well mitochondria defend their glutathione redox status when challenged with high levels of reduced glutathione, but the redox challenge elicited the same H2O2/O2 in all species. Furthermore, in vitro anoxia-recovery lowered absolute H2O2 emission (H2O2/mg mitochondrial protein) in all species and negatively impacted state 3 respiration rates in some species, but the responses were not related to hypoxia tolerance. Overall, we clearly demonstrate a relationship between hypoxia tolerance and complex I and II flux capacities in sculpins, but the differences in complex flux capacity do not appear to be directly related to variation in ROS metabolism.
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Affiliation(s)
- Gigi Y. Lau
- Department of Zoology, The University of British Columbia, 6270 University Boulevard, Vancouver, B.C., Canada, V6T 1Z4
| | - Jeffrey G. Richards
- Department of Zoology, The University of British Columbia, 6270 University Boulevard, Vancouver, B.C., Canada, V6T 1Z4
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8
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Bordt EA, Clerc P, Roelofs BA, Saladino AJ, Tretter L, Adam-Vizi V, Cherok E, Khalil A, Yadava N, Ge SX, Francis TC, Kennedy NW, Picton LK, Kumar T, Uppuluri S, Miller AM, Itoh K, Karbowski M, Sesaki H, Hill RB, Polster BM. The Putative Drp1 Inhibitor mdivi-1 Is a Reversible Mitochondrial Complex I Inhibitor that Modulates Reactive Oxygen Species. Dev Cell 2017; 40:583-594.e6. [PMID: 28350990 PMCID: PMC5398851 DOI: 10.1016/j.devcel.2017.02.020] [Citation(s) in RCA: 362] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 01/19/2017] [Accepted: 02/24/2017] [Indexed: 11/15/2022]
Abstract
Mitochondrial fission mediated by the GTPase dynamin-related protein 1 (Drp1) is an attractive drug target in numerous maladies that range from heart disease to neurodegenerative disorders. The compound mdivi-1 is widely reported to inhibit Drp1-dependent fission, elongate mitochondria, and mitigate brain injury. Here, we show that mdivi-1 reversibly inhibits mitochondrial complex I-dependent O2 consumption and reverse electron transfer-mediated reactive oxygen species (ROS) production at concentrations (e.g., 50 μM) used to target mitochondrial fission. Respiratory inhibition is rescued by bypassing complex I using yeast NADH dehydrogenase Ndi1. Unexpectedly, respiratory impairment by mdivi-1 occurs without mitochondrial elongation, is not mimicked by Drp1 deletion, and is observed in Drp1-deficient fibroblasts. In addition, mdivi-1 poorly inhibits recombinant Drp1 GTPase activity (Ki > 1.2 mM). Overall, these results suggest that mdivi-1 is not a specific Drp1 inhibitor. The ability of mdivi-1 to reversibly inhibit complex I and modify mitochondrial ROS production may contribute to effects observed in disease models.
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Affiliation(s)
- Evan A Bordt
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Pascaline Clerc
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Brian A Roelofs
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Andrew J Saladino
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Pathology and Laboratory Medicine Service, Department of Veterans Affairs Medical Center, Baltimore, MD 21201, USA
| | - László Tretter
- MTA-SE Laboratory for Neurobiochemistry, Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary
| | - Vera Adam-Vizi
- MTA-SE Laboratory for Neurobiochemistry, Department of Medical Biochemistry, Semmelweis University, Budapest 1094, Hungary
| | - Edward Cherok
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ahmed Khalil
- Pioneer Valley Life Sciences Institute, Springfield, MA 01109, USA; Baystate Medical Center, Springfield, MA 01109, USA
| | - Nagendra Yadava
- Pioneer Valley Life Sciences Institute, Springfield, MA 01109, USA; Baystate Medical Center, Springfield, MA 01109, USA; Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Shealinna X Ge
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - T Chase Francis
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Nolan W Kennedy
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Lora K Picton
- Department of Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Tanya Kumar
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sruti Uppuluri
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Alexandrea M Miller
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kie Itoh
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Mariusz Karbowski
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Hiromi Sesaki
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Brian M Polster
- Department of Anesthesiology, The Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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9
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Ambrus A, Nemeria NS, Torocsik B, Tretter L, Nilsson M, Jordan F, Adam-Vizi V. Formation of reactive oxygen species by human and bacterial pyruvate and 2-oxoglutarate dehydrogenase multienzyme complexes reconstituted from recombinant components. Free Radic Biol Med 2015; 89:642-50. [PMID: 26456061 PMCID: PMC4684775 DOI: 10.1016/j.freeradbiomed.2015.10.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 09/18/2015] [Accepted: 10/03/2015] [Indexed: 01/25/2023]
Abstract
Individual recombinant components of pyruvate and 2-oxoglutarate dehydrogenase multienzyme complexes (PDHc, OGDHc) of human and Escherichia coli (E. coli) origin were expressed and purified from E. coli with optimized protocols. The four multienzyme complexes were each reconstituted under optimal conditions at different stoichiometric ratios. Binding stoichiometries for the highest catalytic efficiency were determined from the rate of NADH generation by the complexes at physiological pH. Since some of these complexes were shown to possess 'moonlighting' activities under pathological conditions often accompanied by acidosis, activities were also determined at pH 6.3. As reactive oxygen species (ROS) generation by the E3 component of hOGDHc is a pathologically relevant feature, superoxide generation by the complexes with optimal stoichiometry was measured by the acetylated cytochrome c reduction method in both the forward and the reverse catalytic directions. Various known affectors of physiological activity and ROS production, including Ca(2+), ADP, lipoylation status or pH, were investigated. The human complexes were also reconstituted with the most prevalent human pathological mutant of the E3 component, G194C and characterized; isolated human E3 with the G194C substitution was previously reported to have an enhanced ROS generating capacity. It is demonstrated that: i. PDHc, similarly to OGDHc, is able to generate ROS and this feature is displayed by both the E. coli and human complexes, ii. Reconstituted hPDHc generates ROS at a significantly higher rate as compared to hOGDHc in both the forward and the reverse reactions when ROS generation is calculated for unit mass of their common E3 component, iii. The E1 component or E1-E2 subcomplex generates significant amount of ROS only in hOGDHc; iv. Incorporation of the G194C variant of hE3, the result of a disease-causing mutation, into reconstituted hOGDHc and hPDHc indeed leads to a decreased activity of both complexes and higher ROS generation by only hOGDHc and only in its reverse reaction.
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Affiliation(s)
- Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Natalia S Nemeria
- Department of Chemistry, Rutgers, the State University, Newark, NJ 07102, USA
| | - Beata Torocsik
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Laszlo Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Mattias Nilsson
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Frank Jordan
- Department of Chemistry, Rutgers, the State University, Newark, NJ 07102, USA
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary.
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Ferreira GK, Cardoso MR, Jeremias IC, Gonçalves CL, Freitas KV, Antonini R, Scaini G, Rezin GT, Quevedo J, Streck EL. Fluvoxamine alters the activity of energy metabolism enzymes in the brain. ACTA ACUST UNITED AC 2014; 36:220-6. [PMID: 24676049 DOI: 10.1590/1516-4446-2013-1202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 10/23/2013] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Several studies support the hypothesis that metabolism impairment is involved in the pathophysiology of depression and that some antidepressants act by modulating brain energy metabolism. Thus, we evaluated the activity of Krebs cycle enzymes, the mitochondrial respiratory chain, and creatine kinase in the brain of rats subjected to prolonged administration of fluvoxamine. METHODS Wistar rats received daily administration of fluvoxamine in saline (10, 30, and 60 mg/kg) for 14 days. Twelve hours after the last administration, rats were killed by decapitation and the prefrontal cortex, cerebral cortex, hippocampus, striatum, and cerebellum were rapidly isolated. RESULTS The activities of citrate synthase, malate dehydrogenase, and complexes I, II-III, and IV were decreased after prolonged administration of fluvoxamine in rats. However, the activities of complex II, succinate dehydrogenase, and creatine kinase were increased. CONCLUSIONS Alterations in activity of energy metabolism enzymes were observed in most brain areas analyzed. Thus, we suggest that the decrease in citrate synthase, malate dehydrogenase, and complexes I, II-III, and IV can be related to adverse effects of pharmacotherapy, but long-term molecular adaptations cannot be ruled out. In addition, we demonstrated that these changes varied according to brain structure or biochemical analysis and were not dose-dependent.
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Affiliation(s)
- Gabriela K Ferreira
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
| | - Mariane R Cardoso
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
| | - Isabela C Jeremias
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
| | - Cinara L Gonçalves
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
| | - Karolina V Freitas
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
| | - Rafaela Antonini
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
| | - Giselli Scaini
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
| | - Gislaine T Rezin
- Clinical and Experimental Pathophysiology Laboratory, Graduate Program in Health Sciences, Universidade do Sul de Santa Catarina (UNISUL), Tubarão, SC, Brazil
| | - João Quevedo
- National Science and Technology Institute for Translational Medicine (INCT-TM), Porto Alegre, RS, Brazil
| | - Emilio L Streck
- Bioenergetics Laboratory, Center of Excellence in Applied Neurosciences of Santa Catarina (NENASC), Graduate Program in Health Sciences, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, Brazil
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Gong P, Hua R, Zhang Y, Zhao H, Tang Z, Mei X, Zhang M, Cui J, Li C. Hypothermia-induced neuroprotection is associated with reduced mitochondrial membrane permeability in a swine model of cardiac arrest. J Cereb Blood Flow Metab 2013; 33:928-34. [PMID: 23486294 PMCID: PMC3677114 DOI: 10.1038/jcbfm.2013.33] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Increasing evidence has shown that mild hypothermia is neuroprotective for comatose patients resuscitated from cardiac arrest, but the mechanism of this protection is not fully understood. The aim of this study was to determine whether prolonged whole-body mild hypothermia inhibits mitochondrial membrane permeability (MMP) in the cerebral cortex after return of spontaneous circulation (ROSC). Thirty-seven inbred Chinese Wuzhishan minipigs were successfully resuscitated after 8 minutes of untreated ventricular fibrillation (VF) and underwent recovery under normothermic (NT) or prolonged whole-body mild hypothermic (HT; 33°C) conditions for 24 or 72 hours. Cerebral samples from the frontal cortex were collected at 24 and 72 hours after ROSC. Mitochondria were isolated by differential centrifugation. At 24 hours, relative to NT, HT was associated with reductions in opening of the mitochondrial permeability transition pore, release of pro-apoptotic substances from mitochondria, caspase 3 cleavage, apoptosis, and neurologic deficit scores, as well as increases in mitochondrial membrane potential and mitochondrial respiration. Together, these findings suggest that mild hypothermia inhibits ischemia-induced increases in MMP, which may provide neuroprotection against cerebral injury after cardiac arrest.
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Affiliation(s)
- Ping Gong
- Department of Emergency, First Hospital affiliated to Dalian Medical University, Dalian, China
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Aldakkak M, Stowe DF, Dash RK, Camara AK. Mitochondrial handling of excess Ca2+ is substrate-dependent with implications for reactive oxygen species generation. Free Radic Biol Med 2013; 56:193-203. [PMID: 23010495 PMCID: PMC3542420 DOI: 10.1016/j.freeradbiomed.2012.09.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/13/2012] [Accepted: 09/16/2012] [Indexed: 10/27/2022]
Abstract
The mitochondrial electron transport chain is the major source of reactive oxygen species (ROS) during cardiac ischemia. Several mechanisms modulate ROS production; one is mitochondrial Ca(2+) uptake. Here we sought to elucidate the effects of extramitochondrial Ca(2+) (e[Ca(2+)]) on ROS production (measured as H(2)O(2) release) from complexes I and III. Mitochondria isolated from guinea pig hearts were preincubated with increasing concentrations of CaCl(2) and then energized with the complex I substrate Na(+) pyruvate or the complex II substrate Na(+) succinate. Mitochondrial H(2)O(2) release rates were assessed after giving either rotenone or antimycin A to inhibit complex I or III, respectively. After pyruvate, mitochondria maintained a fully polarized membrane potential (ΔΨ; assessed using rhodamine 123) and were able to generate NADH (assessed using autofluorescence) even with excess e[Ca(2+)] (assessed using CaGreen-5N), whereas they remained partially depolarized and did not generate NADH after succinate. This partial ΔΨ depolarization with succinate was accompanied by a large release in H(2)O(2) (assessed using Amplex red/horseradish peroxidase) with later addition of antimycin A. In the presence of excess e[Ca(2+)], adding cyclosporin A to inhibit mitochondrial permeability transition pore opening restored ΔΨ and significantly decreased antimycin A-induced H(2)O(2) release. Succinate accumulates during ischemia to become the major substrate utilized by cardiac mitochondria. The inability of mitochondria to maintain a fully polarized ΔΨ under excess e[Ca(2+)] when succinate, but not pyruvate, is the substrate may indicate a permeabilization of the mitochondrial membrane, which enhances H(2)O(2) emission from complex III during ischemia.
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Affiliation(s)
- Mohammed Aldakkak
- Department of Anesthesiology, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - David F. Stowe
- Department of Anesthesiology, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Department of Physiology, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Cardiovascular Research Center, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Department of Anesthesiology, VA Medical Center Research Service, 5000 W. National Ave., Milwaukee, WI 53295, USA
- Department of Biomedical Engineering, Marquette University, 615 N 11th St, Milwaukee, WI 53233, USA
| | - Ranjan K. Dash
- Department of Physiology, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Biotechnology and Bioengineering Center, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Amadou K.S. Camara
- Department of Anesthesiology, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Cardiovascular Research Center, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Corresponding author: Amadou K.S. Camara Ph.D., M4280, The Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA. Tel: 001-414-456-5624, Fax: 001-414-456-6507,
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Polster BM. AIF, reactive oxygen species, and neurodegeneration: a "complex" problem. Neurochem Int 2012; 62:695-702. [PMID: 23246553 DOI: 10.1016/j.neuint.2012.12.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 11/26/2012] [Accepted: 12/05/2012] [Indexed: 12/21/2022]
Abstract
Apoptosis-inducing factor (AIF) is a flavin-binding mitochondrial intermembrane space protein that is implicated in diverse but intertwined processes that include maintenance of electron transport chain function, reactive oxygen species regulation, cell death, and neurodegeneration. In acute brain injury, AIF acquires a pro-death role upon translocation from the mitochondria to the nucleus, where it initiates chromatin condensation and large-scale DNA fragmentation. Although harlequin mice exhibiting an 80-90% global reduction in AIF protein are resistant to numerous forms of acute brain injury, they paradoxically undergo slow, progressive neurodegeneration beginning at three months of age. Brain deterioration, accompanied by markers of oxidative stress, is most pronounced in the cerebellum and retina, although it also occurs in the cortex, striatum, and thalamus. Loss of an AIF pro-survival function linked to assembly or stabilization of electron transport chain complex I underlies chronic neurodegeneration. To date, most studies of neurodegeneration have failed to adequately separate the relative importance of the mitochondrial and nuclear functions of AIF in determining the extent of injury, or whether oxidative stress plays a causative role. This review explores the complicated relationship among AIF, complex I, and the regulation of mitochondrial reactive oxygen species levels. It also discusses the controversial role of complex I deficiency in Parkinson's disease, and what can be learned from the AIF- and complex I-depleted harlequin mouse.
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Affiliation(s)
- Brian M Polster
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, 685 W. Baltimore St., MSTF 5-34, Baltimore, MD 21201, USA.
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Tretter L, Adam-Vizi V. High Ca2+ load promotes hydrogen peroxide generation via activation of α-glycerophosphate dehydrogenase in brain mitochondria. Free Radic Biol Med 2012; 53:2119-30. [PMID: 23022874 DOI: 10.1016/j.freeradbiomed.2012.09.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Revised: 09/03/2012] [Accepted: 09/20/2012] [Indexed: 12/22/2022]
Abstract
H(2)O(2) generation associated with α-glycerophosphate (α-GP) oxidation was addressed in guinea pig brain mitochondria challenged with high Ca(2+) load (10 μM). Exposure to 10 μM Ca(2+) induced an abrupt 2.5-fold increase in H(2)O(2) release compared to that measured in the presence of a physiological cytosolic Ca(2+) concentration (100 nM) from mitochondria respiring on 5 mM α-GP in the presence of ADP (2 mM). The Ca(2+)-induced stimulation of H(2)O(2) generation was reversible and unaltered by the uniporter blocker Ru 360, indicating that it did not require Ca(2+) uptake into mitochondria. Enhanced H(2)O(2) generation by Ca(2+) was also observed in the absence of ADP when mitochondria exhibited permeability transition pore opening with a decrease in the NAD(P)H level, dissipation of membrane potential, and mitochondrial swelling. Furthermore, mitochondria treated with the pore-forming peptide alamethicin also responded with an elevated H(2)O(2) generation to a challenge with 10 μM Ca(2+). Ca(2+)-induced promotion of H(2)O(2) formation was further enhanced by the complex III inhibitor myxothiazol. With 20 mM α-GP concentration, stimulation of H(2)O(2) formation by Ca(2+) was detected only in the presence, not in the absence, of ADP. It is concluded that α-glycerophosphate dehydrogenase, which is accessible to and could be activated by a rise in the level of cytosolic Ca(2+), makes a major contribution to Ca(2+)-stimulated H(2)O(2) generation. This work highlights a unique high-Ca(2+)-stimulated reactive oxygen species-forming mechanism in association with oxidation of α-GP, which is largely independent of the bioenergetic state and can proceed even in damaged, functionally incompetent mitochondria.
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Affiliation(s)
- Laszlo Tretter
- Department of Medical Biochemistry, Semmelweis University, Budapest H-1444, Hungary
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15
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Zhuravliova E, Barbakadze T, Jojua N, Zaalishvili E, Shanshiashvili L, Natsvlishvili N, Kalandadze I, Narmania N, Chogovadze I, Mikeladze D. Synaptic and Non-Synaptic Mitochondria in Hippocampus of Adult Rats Differ in Their Sensitivity to Hypothyroidism. Cell Mol Neurobiol 2012; 32:1311-21. [DOI: 10.1007/s10571-012-9857-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 05/31/2012] [Indexed: 11/28/2022]
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16
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Gonçalves CL, Rezin GT, Ferreira GK, Jeremias IC, Cardoso MR, Carvalho-Silva M, Zugno AI, Quevedo J, Streck EL. Differential effects of escitalopram administration on metabolic parameters of cortical and subcortical brain regions of Wistar rats. Acta Neuropsychiatr 2012; 24:147-54. [PMID: 26953007 DOI: 10.1111/j.1601-5215.2011.00592.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Considering that mitochondria may be drug targets and some characteristics of drug-mitochondria interactions may still be misjudged because of the difficulty in foreseeing and understanding all possible implications of the complex pathophysiology of mitochondria, our study aimed to investigate the effect of escitalopram on the activity of enzymes of mitochondrial energy metabolism. METHODS Animals received daily administration of escitalopram dissolved in saline [10 mg/kg, intraperitoneal (IP)] at 1.0 ml/kg volume for 14 days. Control rats received an equivalent volume of saline, 1.0 ml/kg (IP), for the same treatment period. Twelve hours after last injection, rats were killed by decapitation and brain areas were rapidly isolated. The samples were homogenised and the activities of mitochondrial respiratory chain complexes, some enzymes of Krebs cycle (citrate synthase, malate dehydrogenase and succinate dehydrogenase) and creatine kinase were measured. RESULTS We verified that chronic administration of escitalopram decreased the activities of complexes I and II-III in cerebellum, hippocampus, striatum and posterior cortex whereas prefrontal cortex was not affected. Complex II activity was decreased only in striatum without affecting prefrontal cortex, hippocampus, cerebellum and posterior cortex. However, chronic administration of escitalopram did not affect complex IV and enzymes of Krebs cycle activities as well as creatine kinase. CONCLUSION In this study we showed a decrease in the activities of complexes I and II-III in most of the brain structures analysed and complex II activity was decreased only in striatum. However, it remains to be determined if mitochondrial dysfunction is rather a causal or a consequential event of abnormal signalling.
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Affiliation(s)
- Cinara L Gonçalves
- Laboratório de Bioenergética, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Gislaine T Rezin
- Laboratório de Bioenergética, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Gabriela K Ferreira
- Laboratório de Bioenergética, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Isabela C Jeremias
- Laboratório de Bioenergética, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Mariane R Cardoso
- Laboratório de Bioenergética, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Milena Carvalho-Silva
- Laboratório de Bioenergética, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Alexandra I Zugno
- Instituto Nacional de Ciência e Tecnologia Translacional em Medicina, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - João Quevedo
- Instituto Nacional de Ciência e Tecnologia Translacional em Medicina, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Emilio L Streck
- Laboratório de Bioenergética, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
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Abelaira HM, Réus GZ, Ribeiro KF, Zappellini G, Ferreira GK, Gomes LM, Carvalho-Silva M, Luciano TF, Marques SO, Streck EL, Souza CT, Quevedo J. Effects of acute and chronic treatment elicited by lamotrigine on behavior, energy metabolism, neurotrophins and signaling cascades in rats. Neurochem Int 2011; 59:1163-74. [DOI: 10.1016/j.neuint.2011.10.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 10/13/2011] [Accepted: 10/15/2011] [Indexed: 12/29/2022]
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18
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Scaini G, Maggi DD, De-Nês BT, Gonçalves CL, Ferreira GK, Teodorak BP, Bez GD, Ferreira GC, Schuck PF, Quevedo J, Streck EL. Activity of mitochondrial respiratory chain is increased by chronic administration of antidepressants. Acta Neuropsychiatr 2011; 23:112-8. [PMID: 26952897 DOI: 10.1111/j.1601-5215.2011.00548.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Depressive disorders, including major depression, are serious and disabling for affected patients. Although the neurobiological understanding of major depressive disorder focuses mainly on the monoamine hypothesis, the exact pathophysiology of depression is not fully understood. METHODS Animals received daily intra-peritoneal injections of paroxetine (10 mg/kg), nortriptyline (15 mg/kg) or venlafaxine (10 mg/kg) in 1.0 ml/kg volume for 15 days. Twelve hours after the last injection, the rats were killed by decapitation, where the brain was removed and homogenised. The activities of mitochondrial respiratory chain complexes in different brain structures were measured. RESULTS We first verified that chronic administration of paroxetine increased complex I activity in prefrontal cortex, hippocampus, striatum and cerebral cortex. In addition, complex II activity was increased by the same drug in hippocampus, striatum and cerebral cortex and complex IV activity in prefrontal cortex. Furthermore, chronic administration of nortriptyline increased complex II activity in hippocampus and striatum and complex IV activity in prefrontal cortex, striatum and cerebral cortex. Finally, chronic administration of venlafaxine increased complex II activity in hippocampus, striatum and cerebral cortex and complex IV activity in prefrontal cortex. CONCLUSION On the basis of the present findings, it is tempting to speculate that an increase in brain energy metabolism by the antidepressant paroxetine, nortriptyline and venlafaxine could play a role in the mechanism of action of these drugs. These data corroborate with other studies suggesting that some antidepressants modulate brain energy metabolism.
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Affiliation(s)
- Giselli Scaini
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Débora D Maggi
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Bruna T De-Nês
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Cinara L Gonçalves
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Gabriela K Ferreira
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Brena P Teodorak
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Gisele D Bez
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - Gustavo C Ferreira
- Programa de Pós-graduação em Ciências da Saúde, Universidade do Sul de Santa Catarina, Tubarão, SC, Brazil
| | - Patricia F Schuck
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
| | - João Quevedo
- Instituto Nacional de Ciência e Tecnologia Translacional em Medicina
| | - Emilio L Streck
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
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Tretter L, Biagioni Angeli E, Ardestani MR, Goracci G, Adam-Vizi V. Reversible inhibition of hydrogen peroxide elimination by calcium in brain mitochondria. J Neurosci Res 2011; 89:1965-72. [PMID: 21541982 DOI: 10.1002/jnr.22658] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/03/2011] [Accepted: 03/14/2011] [Indexed: 11/07/2022]
Abstract
In the present work, the Ca(2+) dependence of mitochondrial H(2) O(2) elimination was investigated. Mitochondria isolated from guinea pig brain were energized by glutamate and malate and incubated with micromolar concentrations of Ca(2+) in the presence of ADP, preventing permeability transition pore formation. After the completion of Ca(2+) uptake, mitochondria were challenged with H(2) O(2) (5 μM), then at various time points residual H(2) O(2) was determined using the Amplex red method and compared with that in mitochondria incubated with H(2) O(2) without Ca(2+) addition. Dose-dependent inhibition of H(2) O(2) elimination by Ca(2+) was detected, which was prevented by the Ca(2+) -uptake inhibitor Ru 360. Stimulation of Ca(2+) release from Ca(2+) -loaded mitochondria by a combined addition of Ru 360 and Na(+) decreased the Ca(2+) -evoked inhibition of H(2) O(2) removal. After Ca(2+) uptake (50 μM), mitochondrial aconitase activity was found to be decreased, which was partially attributable to the impaired elimination of endogenously produced reactive oxygen species. We found that the effects of Ca(2+) and H(2) O(2) on the activity of aconitase were additive. These results confirm that Ca(2+) inhibits elimination of H(2) O(2) in mitochondria and demonstrate that this effect is concentration dependent and reversible. The phenomenon described here can play a role in the modulation of ROS handling under conditions involving excessive cellular Ca(2+) load.
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Affiliation(s)
- Laszlo Tretter
- Department of Medical Biochemistry, Semmelweis University, and Laboratory of Neurobiochemistry and Molecular Physiology, Hungarian Academy of Sciences, Budapest, Hungary
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Panov AV, Vavilin VA, Lyakhovich VV, Brooks BR, Bonkovsky HL. Effect of bovine serum albumin on mitochondrial respiration in the brain and liver of mice and rats. Bull Exp Biol Med 2011; 149:187-90. [PMID: 21113488 DOI: 10.1007/s10517-010-0904-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We studied the effect of BSA (in the isolation medium) on the oxidation rate of succinate, glutamate, pyruvate, and α-ketoglutarate by mitochondria of the brain and liver from C57Bl/6g mice and Taconic Sprague Dawley rats. BSA had no effect on liver mitochondrial respiration, but increased oxidation of substrates (particularly of succinate) in brain mitochondria. Therefore, the major effect of BSA on brain mitochondria is manifested in activation of SDH. The improvement of mitochondrial properties in the brain after treatment with BSA is associated with antioxidant activity of this agent. Our results confirm the hypothesis that inhibition of SDH in brain mitochondria is not the artifact. This process serves as a mechanism protecting neurons from free oxygen radicals during succinate oxidation.
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Affiliation(s)
- A V Panov
- Cannon Research Center, Carolinas Medical Center, Charlotte, North Carolina, USA.
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Adam-Vizi V, Starkov AA. Calcium and mitochondrial reactive oxygen species generation: how to read the facts. J Alzheimers Dis 2010; 20 Suppl 2:S413-26. [PMID: 20421693 DOI: 10.3233/jad-2010-100465] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A number of recent discoveries indicate that abnormal Ca2+ signaling, oxidative stress, and mitochondrial dysfunction are involved in the neuronal damage in Alzheimer's disease. However, the literature on the interactions between these factors is controversial especially in the interpretation of the cause-effect relationship between mitochondrial damage induced by Ca2+ overload and the production of reactive oxygen species (ROS). In this review, we survey the experimental observations on the Ca2+-induced mitochondrial ROS production, explain the sources of controversy in interpreting these results, and discuss the different molecular mechanisms underlying the effect of Ca2+ on the ROS emission by brain mitochondria.
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Affiliation(s)
- Vera Adam-Vizi
- Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group of Hungarian Academy of Sciences, Budapest, Hungary.
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Scaini G, Santos PM, Benedet J, Rochi N, Gomes LM, Borges LS, Rezin GT, Pezente DP, Quevedo J, Streck EL. Evaluation of Krebs cycle enzymes in the brain of rats after chronic administration of antidepressants. Brain Res Bull 2010; 82:224-7. [DOI: 10.1016/j.brainresbull.2010.03.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 03/22/2010] [Indexed: 11/29/2022]
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Komary Z, Tretter L, Adam-Vizi V. Membrane potential-related effect of calcium on reactive oxygen species generation in isolated brain mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:922-8. [PMID: 20230776 DOI: 10.1016/j.bbabio.2010.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/04/2010] [Accepted: 03/06/2010] [Indexed: 01/29/2023]
Abstract
The effect of Ca2+ applied in high concentrations (50 and 300 microM) was addressed on the generation of reactive oxygen species in isolated mitochondria from guinea-pig brain. The experiments were performed in the presence of ADP, a very effective inhibitor of mitochondrial permeability transition. Moderate increase in H2O2 release from mitochondria was induced by Ca2+ applied in 50 microM, but not in 300 microM concentration as measured with Amplex red fluorescent assay starting with a delay of 100-150 sec after exposure to Ca2+. Parallel measurements of membrane potential (DeltaPsim) by safranine fluorescence showed a transient depolarization by Ca2+ followed by the recovery of DeltaPsim to a value, which was more negative than that observed before addition of Ca2+ indicating a relative hyperpolarization. NAD(P)H fluorescence was also increased by Ca2+ given in 50 microM concentration. In mitochondria having high DeltaPsim in the presence of oligomycin or ATP, the basal rate of release of H2O2 was significantly higher than that observed in a medium containing ADP and Ca2+ no longer increased but rather decreased the rate of H2O2 release. With 300 microM Ca2+ only a loss but no tendency of a recovery of DeltaPsim was detected and H2O2 release was unchanged. It is suggested that in the presence of nucleotides the effect of Ca2+ on mitochondrial ROS release is related to changes in DeltaPsim; in depolarized mitochondria, in the presence of ADP, moderate increase in H2O2 release is induced by calcium, but only in <or=100 microM concentration, when after a transient Ca2+-induced depolarization mitochondria became more polarized. In highly polarized mitochondria, in the presence of ATP or oligomycin, where no hyperpolarization follows the Ca2+-induced depolarization, Ca2+ fails to stimulate mitochondrial ROS generation. These effects of calcium (<or=300 microM) are unrelated to mitochondrial permeability transition.
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Affiliation(s)
- Zsofia Komary
- Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group, Hungarian Academy of Sciences, Hungary
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Sarafian TA, Montes C, Imura T, Qi J, Coppola G, Geschwind DH, Sofroniew MV. Disruption of astrocyte STAT3 signaling decreases mitochondrial function and increases oxidative stress in vitro. PLoS One 2010; 5:e9532. [PMID: 20224768 PMCID: PMC2835741 DOI: 10.1371/journal.pone.0009532] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 02/08/2010] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Astrocytes exert a wide variety of functions in health and disease and respond to a wide range of signaling pathways, including members of the Janus-kinase signal transducers and activators of transcription (Jak-STAT) family. We have recently shown that STAT3 is an important regulator of astrocyte reactivity after spinal cord injury in vivo[1]. METHODOLOGY/PRINCIPAL FINDINGS Here, we used both a conditional gene deletion strategy that targets the deletion of STAT3 selectively to astrocytes (STAT3-CKO), and a pharmacological inhibitor of JAK-2, AG490, in cultured astrocytes in vitro, to investigate potential functions and molecules influenced by STAT3 signaling in relation to mitochondrial function and oxidative stress. Our findings show that the absence of STAT3 signaling in astrocytes leads to (i) increased production of superoxide anion and other reactive oxygen species and decreased level of glutathione, (ii) decreased mitochondrial membrane potential and decreased ATP production, and (iii) decreased rate of cell proliferation. Many of the differences observed in STAT3-CKO astrocytes were distinctly altered by exposure to rotenone, suggesting a role for complex I of the mitochondrial electron transport chain. Gene expression microarray studies identified numerous changes in STAT3-CKO cells that may have contributed to the identified deficits in cell function. CONCLUSIONS/SIGNIFICANCE Taken together, these STAT3-dependent alterations in cell function and gene expression have relevance to both reactive gliosis and to the support and protection of surrounding cells in neural tissue.
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Affiliation(s)
- Theodore A Sarafian
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
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Lambert AJ, Buckingham JA, Boysen HM, Brand MD. Low complex I content explains the low hydrogen peroxide production rate of heart mitochondria from the long-lived pigeon, Columba livia. Aging Cell 2010; 9:78-91. [PMID: 19968628 DOI: 10.1111/j.1474-9726.2009.00538.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Across a range of vertebrate species, it is known that there is a negative association between maximum lifespan and mitochondrial hydrogen peroxide production. In this report, we investigate the underlying biochemical basis of the low hydrogen peroxide production rate of heart mitochondria from a long-lived species (pigeon) compared with a short-lived species with similar body mass (rat). The difference in hydrogen peroxide efflux rate was not explained by differences in either superoxide dismutase activity or hydrogen peroxide removal capacity. During succinate oxidation, the difference in hydrogen peroxide production rate between the species was localized to the DeltapH-sensitive superoxide producing site within complex I. Mitochondrial DeltapH was significantly lower in pigeon mitochondria compared with rat, but this difference in DeltapH was not great enough to explain the lower hydrogen peroxide production rate. As judged by mitochondrial flavin mononucleotide content and blue native polyacrylamide gel electrophoresis, pigeon mitochondria contained less complex I than rat mitochondria. Recalculation revealed that the rates of hydrogen peroxide production per molecule of complex I were the same in rat and pigeon. We conclude that mitochondria from the long-lived pigeon display low rates of hydrogen peroxide production because they have low levels of complex I.
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Affiliation(s)
- Adrian J Lambert
- Medical Research Council Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY, UK
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Santos PM, Scaini G, Rezin GT, Benedet J, Rochi N, Jeremias GC, Carvalho-Silva M, Quevedo J, Streck EL. Brain creatine kinase activity is increased by chronic administration of paroxetine. Brain Res Bull 2009; 80:327-30. [PMID: 19772902 DOI: 10.1016/j.brainresbull.2009.09.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 09/12/2009] [Accepted: 09/14/2009] [Indexed: 01/09/2023]
Abstract
Major depression is a serious and recurrent disorder often manifested with symptoms at the psychological, behavioral, and physiological levels. In addition, several works also suggest brain metabolism impairment as a mechanism underlying depression. Creatine kinase (CK) plays a central role in the metabolism of high-energy consuming tissues such as brain, where it functions as an effective buffering system of cellular ATP levels. Considering that CK plays an important role in brain energy homeostasis and that some antidepressants may modulate energy metabolism, we decided to investigate CK activity from rat brain after chronic administration of paroxetine (selective serotonin reuptake inhibitor), nortriptiline (tricyclic antidepressant) and venlafaxine (selective serotonin-norepinephrine reuptake inhibitor). Adult male Wistar rats received daily injections of paroxetine (10 mg/kg), nortriptiline (15 mg/kg), venlafaxine (10 mg/kg) or saline in 1.0 mL/kg volume for 15 days. Twelve hours after the last administration, the rats were killed by decapitation, the hippocampus, striatum and prefrontal cortex were immediately removed, and activity of CK was measured. Our results demonstrated that chronic administration of paroxetine increased CK activity in the prefrontal cortex, hippocampus and striatum of adult rats. On the other hand, nortriptiline and venlafaxine chronic administration did not affect CK activity in these brain areas. In order to verify whether the effect of paroxetine on CK is direct or indirect, we also measured the in vitro effect of this drug on the activity of the enzyme. We verified that paroxetine did not affect CK activity in vitro. Considering that metabolism impairment is probably involved in the pathophysiology of depressive disorders, an increase in CK activity by antidepressants may be an important mechanism of action of these drugs.
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Affiliation(s)
- Patricia M Santos
- Laboratório de Fisiopatologia Experimental, Programa de Pós-graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, SC, Brazil
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27
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Rezin GT, Gonçalves CL, Daufenbach JF, Fraga DB, Santos PM, Ferreira GK, Hermani FV, Comim CM, Quevedo J, Streck EL. Acute administration of ketamine reverses the inhibition of mitochondrial respiratory chain induced by chronic mild stress. Brain Res Bull 2009; 79:418-21. [DOI: 10.1016/j.brainresbull.2009.03.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 03/18/2009] [Accepted: 03/23/2009] [Indexed: 12/21/2022]
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Ambivalent effects of diazoxide on mitochondrial ROS production at respiratory chain complexes I and III. Biochim Biophys Acta Gen Subj 2009; 1790:558-65. [DOI: 10.1016/j.bbagen.2009.01.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 01/27/2009] [Accepted: 01/30/2009] [Indexed: 12/31/2022]
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Mishra MK, Ghosh D, Duseja R, Basu A. Antioxidant potential of Minocycline in Japanese Encephalitis Virus infection in murine neuroblastoma cells: Correlation with membrane fluidity and cell death. Neurochem Int 2009; 54:464-70. [DOI: 10.1016/j.neuint.2009.01.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Accepted: 01/30/2009] [Indexed: 12/27/2022]
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A novel kinetic assay of mitochondrial ATP-ADP exchange rate mediated by the ANT. Biophys J 2009; 96:2490-504. [PMID: 19289073 DOI: 10.1016/j.bpj.2008.12.3915] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 12/08/2008] [Accepted: 12/17/2008] [Indexed: 11/23/2022] Open
Abstract
A novel method exploiting the differential affinity of ADP and ATP to Mg(2+) was developed to measure mitochondrial ADP-ATP exchange rate. The rate of ATP appearing in the medium after addition of ADP to energized mitochondria, is calculated from the measured rate of change in free extramitochondrial [Mg(2+)] reported by the membrane-impermeable 5K(+) salt of the Mg(2+)-sensitive fluorescent indicator, Magnesium Green, using standard binding equations. The assay is designed such that the adenine nucleotide translocase (ANT) is the sole mediator of changes in [Mg(2+)] in the extramitochondrial volume, as a result of ADP-ATP exchange. We also provide data on the dependence of ATP efflux rate within the 6.8-7.8 matrix pH range as a function of membrane potential. Finally, by comparing the ATP-ADP steady-state exchange rate to the amount of the ANT in rat brain synaptic, brain nonsynaptic, heart and liver mitochondria, we provide molecular turnover numbers for the known ANT isotypes.
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31
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Ambrus A, Tretter L, Adam-Vizi V. Inhibition of the alpha-ketoglutarate dehydrogenase-mediated reactive oxygen species generation by lipoic acid. J Neurochem 2009; 109 Suppl 1:222-9. [PMID: 19393031 DOI: 10.1111/j.1471-4159.2009.05942.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Dihydrolipoamide dehydrogenase (LADH) is a flavo-enzyme that serves as a subunit of alpha-ketoglutarate dehydrogenase complex (alpha-KGDHC). Reactive oxygen species (ROS) generation by alpha-KGDHC has been assigned to LADH (E3 subunit) and explained by the diaphorase activity of E3. Dysfunctions of alpha-KGDHC and concurrent ROS production have been implicated in neurodegeneration, ischemia-reperfusion, and other pathological conditions. In this work we investigated the in-depth details of ROS generation by isolated LADH and alpha-KGDHC. We found a parallel generation of superoxide and hydrogen peroxide by the E3 subunit of alpha-KGDHC which could be blocked by lipoic acid (LA) acting on a site upstream of the E3 subunit. The pathologically relevant ROS generation (at high NADH/NAD+ ratio and low pH) in the reverse mode of alpha-KGDHC could also be inhibited by LA. Our results contradict the previously proposed mechanism for pH-dependent ROS generation by LADH, showing no disassembling of the E3 functional homodimer at acidic pH using a physiologically relevant method for the examination. It is also suggested that LA could be beneficial in reducing the cell damage related to excessive ROS generation under pathological conditions.
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Affiliation(s)
- Attila Ambrus
- Department of Medical Biochemistry, Neurobiochemical Research Group, Hungarian Academy of Sciences and Szentagothai Janos Knowledge Center, Semmelweis University, Budapest, Hungary
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Chinta SJ, Rane A, Yadava N, Andersen JK, Nicholls DG, Polster BM. Reactive oxygen species regulation by AIF- and complex I-depleted brain mitochondria. Free Radic Biol Med 2009; 46:939-47. [PMID: 19280713 PMCID: PMC2775507 DOI: 10.1016/j.freeradbiomed.2009.01.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Apoptosis-inducing factor (AIF)-deficient harlequin (Hq) mice undergo neurodegeneration associated with a 40-50% reduction in complex I level and activity. We tested the hypothesis that AIF and complex I regulate reactive oxygen species (ROS) production by brain mitochondria. Isolated Hq brain mitochondria oxidizing complex I substrates displayed no difference compared to wild type (WT) in basal ROS production, H2O2 removal, or ROS production stimulated by complex I inhibitors rotenone or 1-methyl-4-phenylpyridinium. In contrast, ROS production caused by reverse electron transfer to complex I was attenuated by approximately 50% in Hq mitochondria oxidizing the complex II substrate succinate. Basal and rotenone-stimulated rates of H2O2 release from in situ mitochondria did not differ between Hq and WT synaptosomes metabolizing glucose, nor did the level of in vivo oxidative protein carbonyl modifications detected in synaptosomes, brain mitochondria, or homogenates. Our results suggest that AIF does not directly modulate ROS release from brain mitochondria. In addition, they demonstrate that in contrast to ROS produced by mitochondria oxidizing succinate, ROS release from in situ synaptosomal mitochondria or from isolated brain mitochondria oxidizing complex I substrates is not proportional to the amount of complex I. These findings raise the important possibility that complex I contributes less to physiological ROS production by brain mitochondria than previously suggested.
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Panov A, Schonfeld P, Dikalov S, Hemendinger R, Bonkovsky HL, Brooks BR. The neuromediator glutamate, through specific substrate interactions, enhances mitochondrial ATP production and reactive oxygen species generation in nonsynaptic brain mitochondria. J Biol Chem 2009; 284:14448-56. [PMID: 19304986 DOI: 10.1074/jbc.m900985200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The finding that upon neuronal activation glutamate is transported postsynaptically from synaptic clefts and increased lactate availability for neurons suggest that brain mitochondria (BM) utilize a mixture of substrates, namely pyruvate, glutamate, and the tricarboxylic acid cycle metabolites. We studied how glutamate affected oxidative phosphorylation and reactive oxygen species (ROS) production in rat BM oxidizing pyruvate + malate or succinate. Simultaneous oxidation of glutamate + pyruvate + malate increased state 3 and uncoupled respiration by 52 and 71%, respectively. The state 4 ROS generation increased 100% over BM oxidizing pyruvate + malate and 900% over that of BM oxidizing glutamate + malate. Up to 70% of ROS generation was associated with reverse electron transport. These effects of pyruvate + glutamate + malate were observed only with BM and not with liver or heart mitochondria. The effects of glutamate + pyruvate on succinate-supported respiration and ROS generation were not organ-specific and depended only on whether mitochondria were isolated with or without bovine serum albumin. With the non-bovine serum albumin brain and heart mitochondria oxidizing succinate, the addition of pyruvate and glutamate abrogated inhibition of Complex II by oxaloacetate. We conclude that (i) during neuronal activation, simultaneous oxidation of glutamate + pyruvate temporarily enhances neuronal mitochondrial ATP production, and (ii) intrinsic inhibition of Complex II by oxaloacetate is an inherent mechanism that protects against ROS generation during reverse electron transport.
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Affiliation(s)
- Alexander Panov
- Cannon Research Center, Carolinas Medical Center, Charlotte, NC 28203, USA.
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Rezin GT, Cardoso MR, Gonçalves CL, Scaini G, Fraga DB, Riegel RE, Comim CM, Quevedo J, Streck EL. Inhibition of mitochondrial respiratory chain in brain of rats subjected to an experimental model of depression. Neurochem Int 2008; 53:395-400. [DOI: 10.1016/j.neuint.2008.09.012] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2008] [Revised: 09/19/2008] [Accepted: 09/22/2008] [Indexed: 12/27/2022]
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Gonzalez LE, Juknat AA, Venosa AJ, Verrengia N, Kotler ML. Manganese activates the mitochondrial apoptotic pathway in rat astrocytes by modulating the expression of proteins of the Bcl-2 family. Neurochem Int 2008; 53:408-15. [PMID: 18930091 DOI: 10.1016/j.neuint.2008.09.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 09/03/2008] [Accepted: 09/05/2008] [Indexed: 01/05/2023]
Abstract
Manganese induces the central nervous system injury leading to manganism, by mechanisms not completely understood. Chronic exposure to manganese generates oxidative stress and induces the mitochondrial permeability transition. In the present study, we characterized apoptotic cell death mechanisms associated with manganese toxicity in rat cortical astrocytes and demonstrated that (i) Mn treatment targets the mitochondria and induces mitochondrial membrane depolarization followed by cytochrome c release to the cytoplasm, (ii) Mn induces both effector caspases 3/7 and 6 as well as PARP-1 cleavage and (iii) Mn shifts the balance of cell death/survival of Bcl-2 family proteins to favor the apoptotic demise of astrocytes. Our model system using cortical rat astrocytes treated with Mn would emerge as a good tool for investigations aimed to elucidate the role of apoptosis in manganism.
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Affiliation(s)
- Laura E Gonzalez
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina
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Zoccarato F, Cappellotto M, Alexandre A. Clorgyline and other propargylamine derivatives as inhibitors of succinate-dependent H(2)O(2) release at NADH:UBIQUINONE oxidoreductase (Complex I) in brain mitochondria. J Bioenerg Biomembr 2008; 40:289-96. [PMID: 18763029 DOI: 10.1007/s10863-008-9160-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 07/16/2008] [Indexed: 02/07/2023]
Abstract
Complex I is the main O(2)(-) producer of the mitochondrial respiratory chain. O(2)(-) release is low with NAD-linked substrates and increases strongly during succinate oxidation, which increases the QH(2)/Q ratio and is rotenone sensitive. We show that the succinate dependent O(2)(-) production (measured as H(2)O(2) release) is inhibited by propargylamine containing compounds (clorgyline, CGP 3466B, rasagiline and TVP-1012). The inhibition does not affect membrane potential and is unaffected by DeltapH modifications. Mitochondrial respiration is similarly unaffected. The propargylamines inhibition of O(2)(-)/H(2)O(2) production is monitored also in the presence of the Parkinson's disease toxin dopaminochrome which stimulates O(2)(-) release. Propargylamine-containing compounds are the first pharmacological inhibitors described for O(2)(-) release at Complex I.
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Affiliation(s)
- Franco Zoccarato
- Dipartimento di Chimica Biologica and Istituto di Neuroscienze, Sezione di Biomembrane (Consiglio Nazionale delle Ricerche), Università di Padova, Padova, Italy
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Komary Z, Tretter L, Adam-Vizi V. H2O2 generation is decreased by calcium in isolated brain mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:800-7. [PMID: 18522799 DOI: 10.1016/j.bbabio.2008.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 04/30/2008] [Accepted: 05/08/2008] [Indexed: 10/22/2022]
Abstract
Release of H(2)O(2) in response to Ca(2+) loads (1-100 microM) was investigated using Amplex red fluorescent assay in isolated guinea-pig brain mitochondria respiring on glutamate plus malate or succinate. In mitochondria challenged with Ca(2+) (10 microM), in the absence of adenine nucleotides and inhibitors of the respiratory chain, the rate of H(2)O(2) release, taken as an indication of H(2)O(2) production, was decreased by 21.8+/-1.6% in the presence of NADH-linked substrates and by 86.5+/-1.8% with succinate. Parallel with this, a Ca(2+)-induced loss in NAD(P)H fluorescence, sustained depolarization, decrease in fluorescent light scattering signal and in calcein fluorescence were detected indicating an increased permeability and swelling of mitochondria, which were prevented by ADP (2 mM). In the presence of ADP H(2)O(2) release from mitochondria was decreased, but Ca(2+) no longer influenced the generation of H(2)O(2). We suggest that the decreased H(2)O(2) generation induced by Ca(2+) is related to depolarization and NAD(P)H loss resulting from a non-specific permeability increase of the mitochondrial inner membrane.
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Affiliation(s)
- Zsofia Komary
- Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group, Hungarian Academy of Sciences, Szentagothai Knowledge Center, Hungary
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Caspersen CS, Sosunov A, Utkina-Sosunova I, Ratner VI, Starkov AA, Ten VS. An isolation method for assessment of brain mitochondria function in neonatal mice with hypoxic-ischemic brain injury. Dev Neurosci 2008; 30:319-24. [PMID: 18349523 DOI: 10.1159/000121416] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 11/28/2007] [Indexed: 11/19/2022] Open
Abstract
This work was undertaken to develop a method for the isolation of mitochondria from a single cerebral hemisphere in neonatal mice. Mitochondria from the normal mouse brain hemisphere isolated by the proposed method exhibited a good respiratory control ratio of 6.39 +/- 0.53 during glutamate-malate-induced phosphorylating respiration. Electron microscopy showed intact mitochondria. The applicability of this method was tested on mitochondria isolated from naïve mice and their littermates subjected to hypoxic-ischemic insult. Hypoxic-ischemic insult prior to reperfusion resulted in a significant (p < 0.01) inhibition of phosphorylating respiration compared to naïve littermates. This was associated with a profound depletion of the ATP content in the ischemic hemisphere. The expression for Mn superoxide dismutase and cytochrome C (markers for the integrity of the mitochondrial matrix and outer membrane) was determined by Western blot to control for mitochondrial integrity and quantity in the compared samples. Thus, we have developed a method for the isolation of the cerebral mitochondria from a single hemisphere adapted to neonatal mice. This method may serve as a valuable tool to study mitochondrial function in a mouse model of immature brain injury. In addition, the suggested method enables us to examine the mitochondrial functional phenotype in immature mice with a targeted genetic alteration.
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High rates of superoxide production in skeletal-muscle mitochondria respiring on both complex I- and complex II-linked substrates. Biochem J 2008; 409:491-9. [PMID: 17916065 DOI: 10.1042/bj20071162] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Despite the considerable interest in superoxide as a potential cause of pathology, the mechanisms of its deleterious production by mitochondria remain poorly understood. Previous studies in purified mitochondria have found that the highest rates of superoxide production are observed with succinate-driven reverse-electron transfer through complex I, although the physiological importance of this pathway is disputed because it necessitates high concentrations of succinate and is thought not to occur when NAD is in the reduced state. However, very few studies have examined the rates of superoxide production with mitochondria respiring on both NADH-linked (e.g. glutamate) and complex II-linked substrates. In the present study, we find that the rates of superoxide production (measured indirectly as H2O2) with glutamate+succinate (approximately 1100 pmol of H2O2 x min(-1) x mg(-1)) were unexpectedly much higher than with succinate (approximately 400 pmol of H2O2 x min(-1) x mg(-1)) or glutamate (approximately 80 pmol of H2O2 x min(-1) x mg(-1)) alone. Superoxide production with glutamate+succinate remained high even at low substrate concentrations (<1 mM), was decreased by rotenone and was completely eliminated by FCCP (carbonyl cyanide p-trifluoromethoxyphenylhydrazone), indicating that it must in large part originate from reverse-electron transfer through complex I. Similar results were obtained when glutamate was replaced with pyruvate, alpha-ketoglutarate or palmitoyl carnitine. In contrast, superoxide production was consistently lowered by the addition of malate (malate+succinate approximately 30 pmol of H2O2 x min(-1) x mg(-1)). We propose that the inhibitory action of malate on superoxide production can be explained by oxaloacetate inhibition of complex II. In summary, the present results indicate that reverse-electron transfer-mediated superoxide production can occur under physiologically realistic substrate conditions and suggest that oxaloacetate inhibition of complex II may be an adaptive mechanism to minimize this.
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Chipana C, García-Ratés S, Camarasa J, Pubill D, Escubedo E. Different oxidative profile and nicotinic receptor interaction of amphetamine and 3,4-methylenedioxy-methamphetamine. Neurochem Int 2008; 52:401-10. [PMID: 17716785 DOI: 10.1016/j.neuint.2007.07.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Revised: 07/10/2007] [Accepted: 07/18/2007] [Indexed: 11/20/2022]
Abstract
d-Amphetamine (AMPH) and MDMA increased intracellular production of reactive oxygen species (ROS) in isolated mouse striatal synaptosomes. MDMA showed a maximal oxidative effect at 50-100 microM. However, for AMPH a double maximum was obtained, the first between 0.1 and 1 microM and the second at 1mM. No oxidative effect was present in synaptosomes from reserpinized mice. Cocaine and l-deprenyl inhibited MDMA and AMPH (0.1 microM) ROS production but not that of AMPH at a higher concentration (1mM). When this high concentration was used, its oxidative effect was abolished by a phospholipase A(2) inhibitor. Delta(9)-Tetrahydrocannabinol fully prevented the oxidative effect of AMPH and MDMA, by a CB(1) receptor-independent mechanism, as did it NPC 15437 and genistein. The pro-oxidative effect induced by AMPH and MDMA showed a strong dependence on calcium (extracellular and from internal stores) and also was inhibited by nicotinic receptor (nAChR) antagonists dihydro-beta-erythroidine, methyllycaconitine (MLA) and alpha-bungarotoxin. MDMA displaced [(3)H]epibatidine and [(3)H]MLA binding with higher affinity than AMPH. Both amphetamines competitively displaced [(3)H]epibatidine from heteromeric receptors but results obtained from [(3)H]MLA binding demonstrated a non-competitive profile. Preincubation of PC12 cells with AMPH or MDMA reduced [(3)H]dopamine uptake. For MDMA, this effect was prevented by MLA. To summarize, comparing AMPH and MDMA we have demonstrated that these drugs induce an oxidative effect dependent on drug concentration and also reduce dopamine uptake. Processes that are known to affect dopamine transporter functionality also seem to modulate amphetamine derivatives-induced ROS production. For MDMA, acute effects tested are blocked by nAChR antagonists, which points to the possibility that these antagonists could be used to treat some of the adverse effects described in MDMA abusers. Conversely, no implication of nicotinic receptors has been proved for AMPH-induced effects at concentrations achievable in CNS after its administration.
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Affiliation(s)
- C Chipana
- Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia, Nucli Universitari de Pedralbes, Universitat de Barcelona, 08028 Barcelona, Spain
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Long chain fatty acyl-CoA modulation of H(2)O (2) release at mitochondrial complex I. J Bioenerg Biomembr 2008; 40:9-18. [PMID: 18214656 DOI: 10.1007/s10863-008-9126-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Accepted: 11/27/2007] [Indexed: 10/22/2022]
Abstract
Complex I is responsible for most of the mitochondrial H(2)O(2) release, low during the oxidation of the NAD linked substrates and high during succinate oxidation, via reverse electron flow. This H(2)O(2) production appear physiological since it occurs at submillimolar concentrations of succinate also in the presence of NAD substrates in heart (present work) and rat brain mitochondria (Zoccarato et al., Biochem J, 406:125-129, 2007). Long chain fatty acyl-CoAs, but not fatty acids, act as strong inhibitors of succinate dependent H(2)O(2) release. The inhibitory effect of acyl-CoAs is independent of their oxidation, being relieved by carnitine and unaffected or potentiated by malonyl-CoA. The inhibition appears to depend on the unbound form since the acyl-CoA effect decreases at BSA concentrations higher than 2 mg/ml; it is not dependent on DeltapH or Deltap and could depend on the inhibition of reverse electron transfer at complex I, since palmitoyl-CoA inhibits the succinate dependent NAD(P) or acetoacetate reduction.
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Tretter L, Takacs K, Kövér K, Adam-Vizi V. Stimulation of H2O2 generation by calcium in brain mitochondria respiring on α-glycerophosphate. J Neurosci Res 2007; 85:3471-9. [PMID: 17600838 DOI: 10.1002/jnr.21405] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
It has been reported recently (Tretter et al., 2007b) that in isolated guinea pig brain mitochondria supported by alpha-glycerophosphate (alpha-GP) reactive oxygen species (ROS) are produced through the reverse electron transport (RET) in the respiratory chain and by alpha-glycerophosphate dehydrogenase (alpha-GPDH). We studied the effect of calcium on the generation of H(2)O(2) as measured by the Amplex Red fluorescent assay in this model. H(2)O(2) production in alpha-GP-supported mitochondria was increased significantly in the presence of 100, 250, and 500 nM Ca(2+), respectively. In addition, Ca(2+) enhanced the membrane potential, the rate of oxygen consumption, and the NAD(P)H autofluorescence in these mitochondria. Direct measurement of alpha-GPDH activity showed that Ca(2+) stimulated the enzyme by decreasing the Km for alpha-GP. In those mitochondria where RET was eliminated by the Complex I inhibitor rotenone (2 microM) or due to depolarization by ADP (1 mM), the rate of H(2)O(2) formation was smaller and the stimulation of H(2)O(2) generation by Ca(2+) was prevented partly, but the stimulatory effect of Ca(2+) was still significant. These data indicate that in alpha-GP-supported mitochondria activation of alpha-GPDH by Ca(2+) leads to an accelerated RET-mediated ROS generation as well as to a stimulated ROS production by alpha-GPDH.
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Affiliation(s)
- Laszlo Tretter
- Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group, Hungarian Academy of Sciences and Szentagothai Janos Knowledge Center, Budapest, Hungary
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Tretter L, Adam-Vizi V. Uncoupling is without an effect on the production of reactive oxygen species by in situ synaptic mitochondria. J Neurochem 2007; 103:1864-71. [PMID: 17854347 DOI: 10.1111/j.1471-4159.2007.04891.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Earlier reports that generation of reactive oxygen species (ROS) by isolated mitochondria supported by succinate was sensitive to small changes in the mitochondrial membrane potential (DeltaPsim) served as a basis for the concept of 'mild uncoupling' suggesting that a few millivolts decrease in DeltaPsim would be beneficial in neuroprotection because of reducing the production of ROS by mitochondria. In this study, we tested whether ROS generation by in situ mitochondria, which function in a normal cytosolic environment and oxidize glucose-derived physiological substrates, is also dependent on changes in DeltaPsim. The release of H(2)O(2) was measured by the Amplex red fluorescence assay in freshly prepared isolated nerve terminals, synaptosomes incubated in a glucose-containing medium. DeltaPsim was decreased by the uncoupler carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazon (FCCP) (10-200 nmol/L), which accelerated the oxygen consumption, decreased the NADH level and induced depolarization, as shown by the fluorescence indicator JC-1, in in situ mitochondria. These changes were detected at already the smallest FCCP concentration. H(2)O(2) generation, however, was found to be unaltered by FCCP at any of the applied concentration. Depolarization of mitochondria was also induced by veratridine (40 mumol/L), which enhances the cytosolic Na(+) concentration and imposes an ATP demand in synaptosomes. The accelerated oxygen consumption and the small depolarization of in situ mitochondria by veratridine were not paralleled by any significant alteration in the ROS generation. These findings indicate that a basal ROS generation by in situ mitochondria is not sensitive to changes in DeltaPsim challenging the rational of the 'mild uncoupling' theory for neuroprotection and suggest that the DeltaPsim-dependent characteristics of ROS generation is limited mainly to well-coupled succinate-supported isolated mitochondria.
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Affiliation(s)
- Laszlo Tretter
- Department of Medical Biochemistry, Szentagothai Knowledge Center, Semmelweis University; Neurobiochemical Group, Hungarian Academy of Sciences, Budapest, Hungary
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Tretter L, Adam-Vizi V. Moderate dependence of ROS formation on DeltaPsim in isolated brain mitochondria supported by NADH-linked substrates. Neurochem Res 2006; 32:569-75. [PMID: 16933091 DOI: 10.1007/s11064-006-9130-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2006] [Indexed: 11/29/2022]
Abstract
The membrane potential (DeltaPsim) dependence of the generation of reactive oxygen species (ROS) in isolated guinea-pig brain mitochondria respiring on NADH-linked substrates (glutamate plus malate) was addressed. Depolarization by FCCP was without effect on H(2)O(2) formation in the absence of bovine serum albumin (BSA). Addition of BSA (0.025%) to the assay medium hyperpolarized mitochondria by 6.1 +/- 0.9 mV (from 169 +/- 3 to 175.1 +/- 2.1 mV) and increased the rate of H(2)O(2) formation from 207 +/- 4.5 to 312 +/- 12 pmol/min/mg protein. Depolarization by FCCP (5-250 nM) in the presence of BSA decreased H(2)O(2) formation but only to the level observed in the absence of BSA. Rotenone stimulated the formation of H(2)O(2) both in the absence and presence of BSA. It is suggested that H(2)O(2) formation in mitochondria supported by NADH-linked substrates is sensitive to changes in DeltaPsim only when mitochondria are highly polarized and even then, 60% of ROS generation is independent of DeltaPsim. This is in contrast to earlier reports on the highly DeltaPsim sensitive ROS formation related to reverse electron flow observed in well-coupled succinate-supported mitochondria.
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Affiliation(s)
- Laszlo Tretter
- Department of Medical Biochemistry, Semmelweis University, P.O. Box 262, Budapest H-1444, Hungary
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