1
|
Laafi J, Homedan C, Jacques C, Gueguen N, Schmitt C, Puy H, Reynier P, Carmen Martinez M, Malthièry Y. Pro-oxidant effect of ALA is implicated in mitochondrial dysfunction of HepG2 cells. Biochimie 2014; 106:157-66. [PMID: 25220386 DOI: 10.1016/j.biochi.2014.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 08/22/2014] [Indexed: 12/16/2022]
Abstract
Heme biosynthesis begins in the mitochondrion with the formation of delta-aminolevulinic acid (ALA). In acute intermittent porphyria, hereditary tyrosinemia type I and lead poisoning patients, ALA is accumulated in plasma and in organs, especially the liver. These diseases are also associated with neuromuscular dysfunction and increased incidence of hepatocellular carcinoma. Many studies suggest that this damage may originate from ALA-induced oxidative stress following its accumulation. Using the MnSOD as an oxidative stress marker, we showed here that ALA treatment of cultured cells induced ROS production, increasing with ALA concentration. The mitochondrial energetic function of ALA-treated HepG2 cells was further explored. Mitochondrial respiration and ATP content were reduced compared to control cells. For the 300 μM treatment, ALA induced a mitochondrial mass decrease and a mitochondrial network imbalance although neither necrosis nor apoptosis were observed. The up regulation of PGC-1, Tfam and ND5 genes was also found; these genes encode mitochondrial proteins involved in mitochondrial biogenesis activation and OXPHOS function. We propose that ALA may constitute an internal bioenergetic signal, which initiates a coordinated upregulation of respiratory genes, which ultimately drives mitochondrial metabolic adaptation within cells. The addition of an antioxidant, Manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), resulted in improvement of maximal respiratory chain capacity with 300 μM ALA. Our results suggest that mitochondria, an ALA-production site, are more sensitive to pro-oxidant effect of ALA, and may be directly involved in pathophysiology of patients with inherited or acquired porphyria.
Collapse
Affiliation(s)
- Jihane Laafi
- LUNAM Université, INSERM UMR 1063, IBIS, IRIS, rue des capucins, 49100 Angers, France.
| | - Chadi Homedan
- LUNAM Université, INSERM UMR 1063, IBIS, IRIS, rue des capucins, 49100 Angers, France; Centre Hospitalier Universitaire, Département de Biochimie et Génétique, IBIS, IRIS, rue des capucins, 49100 Angers, France.
| | - Caroline Jacques
- LUNAM Université, INSERM UMR 1063, IBIS, IRIS, rue des capucins, 49100 Angers, France.
| | - Naig Gueguen
- Centre Hospitalier Universitaire, Département de Biochimie et Génétique, IBIS, IRIS, rue des capucins, 49100 Angers, France; CNRS UMR 6214 - INSERM 1083, IBIS, IRIS, rue des capucins, 49100 Angers, France.
| | - Caroline Schmitt
- Assistance Publique Hôpitaux de Paris, Centre Français des Porphyries, Hôpital Louis Mourier, Université Paris Diderot, 178 rue des Renouillers, 92700 Colombes, France; INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France; Université Paris Diderot, 5 Rue Thomas Mann, 75013 Paris, France.
| | - Hervé Puy
- Assistance Publique Hôpitaux de Paris, Centre Français des Porphyries, Hôpital Louis Mourier, Université Paris Diderot, 178 rue des Renouillers, 92700 Colombes, France; INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France; Université Paris Diderot, 5 Rue Thomas Mann, 75013 Paris, France.
| | - Pascal Reynier
- Centre Hospitalier Universitaire, Département de Biochimie et Génétique, IBIS, IRIS, rue des capucins, 49100 Angers, France; CNRS UMR 6214 - INSERM 1083, IBIS, IRIS, rue des capucins, 49100 Angers, France.
| | - Maria Carmen Martinez
- LUNAM Université, INSERM UMR 1063, IBIS, IRIS, rue des capucins, 49100 Angers, France.
| | - Yves Malthièry
- LUNAM Université, INSERM UMR 1063, IBIS, IRIS, rue des capucins, 49100 Angers, France; Centre Hospitalier Universitaire, Département de Biochimie et Génétique, IBIS, IRIS, rue des capucins, 49100 Angers, France.
| |
Collapse
|
2
|
Fratz EJ, Hunter GA, Ferreira GC. Expression of murine 5-aminolevulinate synthase variants causes protoporphyrin IX accumulation and light-induced mammalian cell death. PLoS One 2014; 9:e93078. [PMID: 24718052 PMCID: PMC3981678 DOI: 10.1371/journal.pone.0093078] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 03/02/2014] [Indexed: 01/11/2023] Open
Abstract
5-Aminolevulinate synthase (ALAS; EC 2.3.1.37) catalyzes the first committed step of heme biosynthesis in animals. The erythroid-specific ALAS isozyme (ALAS2) is negatively regulated by heme at the level of mitochondrial import and, in its mature form, certain mutations of the murine ALAS2 active site loop result in increased production of protoporphyrin IX (PPIX), the precursor for heme. Importantly, generation of PPIX is a crucial component in the widely used photodynamic therapies (PDT) of cancer and other dysplasias. ALAS2 variants that cause high levels of PPIX accumulation provide a new means of targeted, and potentially enhanced, photosensitization. In order to assess the prospective utility of ALAS2 variants in PPIX production for PDT, K562 human erythroleukemia cells and HeLa human cervical carcinoma cells were transfected with expression plasmids for ALAS2 variants with greater enzymatic activity than the wild-type enzyme. The levels of accumulated PPIX in ALAS2-expressing cells were analyzed using flow cytometry with fluorescence detection. Further, cells expressing ALAS2 variants were subjected to white light treatments (21–22 kLux) for 10 minutes after which cell viability was determined. Transfection of HeLa cells with expression plasmids for murine ALAS2 variants, specifically for those with mutated mitochondrial presequences and a mutation in the active site loop, caused significant cellular accumulation of PPIX, particularly in the membrane. Light treatments revealed that ALAS2 expression results in an increase in cell death in comparison to aminolevulinic acid (ALA) treatment producing a similar amount of PPIX. The delivery of stable and highly active ALAS2 variants has the potential to expand and improve upon current PDT regimes.
Collapse
Affiliation(s)
- Erica J. Fratz
- Department of Molecular Medicine, Morsani College of Medicine, Tampa, Florida, United States of America
| | - Gregory A. Hunter
- Department of Molecular Medicine, Morsani College of Medicine, Tampa, Florida, United States of America
| | - Gloria C. Ferreira
- Department of Molecular Medicine, Morsani College of Medicine, Tampa, Florida, United States of America
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
| |
Collapse
|
3
|
McHugh D, Hu SSJ, Rimmerman N, Juknat A, Vogel Z, Walker JM, Bradshaw HB. N-arachidonoyl glycine, an abundant endogenous lipid, potently drives directed cellular migration through GPR18, the putative abnormal cannabidiol receptor. BMC Neurosci 2010; 11:44. [PMID: 20346144 PMCID: PMC2865488 DOI: 10.1186/1471-2202-11-44] [Citation(s) in RCA: 234] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 03/26/2010] [Indexed: 01/10/2023] Open
Abstract
Background Microglia provide continuous immune surveillance of the CNS and upon activation rapidly change phenotype to express receptors that respond to chemoattractants during CNS damage or infection. These activated microglia undergo directed migration towards affected tissue. Importantly, the molecular species of chemoattractant encountered determines if microglia respond with pro- or anti-inflammatory behaviour, yet the signaling molecules that trigger migration remain poorly understood. The endogenous cannabinoid system regulates microglial migration via CB2 receptors and an as yet unidentified GPCR termed the 'abnormal cannabidiol' (Abn-CBD) receptor. Abn-CBD is a synthetic isomer of the phytocannabinoid cannabidiol (CBD) and is inactive at CB1 or CB2 receptors, but functions as a selective agonist at this Gi/o-coupled GPCR. N-arachidonoyl glycine (NAGly) is an endogenous metabolite of the endocannabinoid anandamide and acts as an efficacious agonist at GPR18. Here, we investigate the relationship between NAGly, Abn-CBD, the unidentified 'Abn-CBD' receptor, GPR18, and BV-2 microglial migration. Results Using Boyden chamber migration experiments, yellow tetrazolium (MTT) conversion, In-cell Western, qPCR and immunocytochemistry we show that NAGly, at sub-nanomolar concentrations, and Abn-CBD potently drive cellular migration in both BV-2 microglia and HEK293-GPR18 transfected cells, but neither induce migration in HEK-GPR55 or non-transfected HEK293 wildtype cells. Migration effects are blocked or attenuated in both systems by the 'Abn-CBD' receptor antagonist O-1918, and low efficacy agonists N-arachidonoyl-serine and cannabidiol. NAGly promotes proliferation and activation of MAP kinases in BV-2 microglia and HEK293-GPR18 cells at low nanomolar concentrations - cellular responses correlated with microglial migration. Additionally, BV-2 cells show GPR18 immunocytochemical staining and abundant GPR18 mRNA. qPCR demonstrates that primary microglia, likewise, express abundant amounts of GPR18 mRNA. Conclusions NAGly is the most effective lipid recruiter of BV-2 microglia currently reported and its effects mimic those of Abn-CBD. The data generated from this study supports the hypothesis that GPR18 is the previously unidentified 'Abn-CBD' receptor. The marked potency of NAGly acting on GPR18 to elicit directed migration, proliferation and perhaps other MAPK-dependent phenomena advances our understanding of the lipid-based signaling mechanisms employed by the CNS to actively recruit microglia to sites of interest. It offers a novel research avenue for developing therapeutics to elicit a self-renewing population of neuroregenerative microglia, or alternatively, to prevent the accumulation of misdirected, pro-inflammatory microglia which contribute to and exacerbate neurodegenerative disease.
Collapse
Affiliation(s)
- Douglas McHugh
- The Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
| | | | | | | | | | | | | |
Collapse
|
4
|
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.
Collapse
Affiliation(s)
- Laura E Gonzalez
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina
| | | | | | | | | |
Collapse
|
5
|
Felitsyn N, McLeod C, Shroads AL, Stacpoole PW, Notterpek L. The heme precursor delta-aminolevulinate blocks peripheral myelin formation. J Neurochem 2008; 106:2068-79. [PMID: 18665889 DOI: 10.1111/j.1471-4159.2008.05552.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Delta-aminolevulinic acid (delta-ALA) is a heme precursor implicated in neurological complications associated with porphyria and tyrosinemia type I. Delta-ALA is also elevated in the urine of animals and patients treated with the investigational drug dichloroacetate (DCA). We postulated that delta-ALA may be responsible, in part, for the peripheral neuropathy observed in subjects receiving DCA. To test this hypothesis, myelinating cocultures of Schwann cells and sensory neurons were exposed to delta-ALA (0.1-1 mM) and analyzed for the expression of neural proteins and lipids and markers of oxidative stress. Exposure of myelinating samples to delta-ALA is associated with a pronounced reduction in the levels of myelin-associated lipids and proteins, including myelin protein zero and peripheral myelin protein 22. We also observed an increase in protein carbonylation and the formation of hydroxynonenal and malondialdehyde after treatment with delta-ALA. Studies of isolated Schwann cells and neurons indicate that glial cells are more vulnerable to this pro-oxidant than neurons, based on a selective decrease in the expression of mitochondrial respiratory chain proteins in glial, but not in neuronal, cells. These results suggest that the neuropathic effects of delta-ALA are attributable, at least in part, to its pro-oxidant properties which damage myelinating Schwann cells.
Collapse
Affiliation(s)
- Natalia Felitsyn
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610-0244, USA
| | | | | | | | | |
Collapse
|
6
|
Andreeva N, Nyamaa A, Haupt H, Gross J, Mazurek B. Recombinant human erythropoietin prevents ischemia-induced apoptosis and necrosis in explant cultures of the rat organ of Corti. Neurosci Lett 2006; 396:86-90. [PMID: 16332412 DOI: 10.1016/j.neulet.2005.11.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Revised: 08/19/2005] [Accepted: 11/07/2005] [Indexed: 01/22/2023]
Abstract
This study was designed to evaluate the effect of recombinant human erythropoietin (rhEPO), insulin-like growth factor-1 (rhIGF-1) and epidermal growth factor (rhEGF) on ischemia-induced hair cell loss in an organotypic cochlea culture. The apical, middle and basal parts of the organs of Corti (newborn rat, postnatal days 3-5) were exposed to ischemia (3.5 h) in glucose-free artificial perilymph (pO2 10-20 mmHg) with or without growth factors. Controls were exposed to normoxia. Twenty-four hours after the onset of ischemia, the cultures were stained using tetramethyl rhodamine isothiocyanate (TRITC) phalloidin (hair cells), propidium iodide (membrane integrity) and apoptosis detection kit (DNA-fragmentation). Ischemia (3.5 h) induced a hair cell loss of 20 and 40% in the middle and basal cochlear parts, respectively, and an increase of the numbers of PI-stained and DNA-fragmented nuclei (controls 0-1, ischemia 4-7 nuclei/100 microm). The basal part was more affected than the apical one. rhEPO and rhIGF-1 significantly attenuated the ischemia-induced hair cell loss by reducing processes involved in apoptosis and necrosis. rhEPO has been in clinical use for more than a decade and found to be well tolerated. Therefore, rhEPO could be an effective drug for the prevention of hearing loss via a hair cell protective mechanism.
Collapse
Affiliation(s)
- Nadezhda Andreeva
- Brain Research Institute, Academy of Medical Sciences, Odukha 5, 105064 Moscow, Russia
| | | | | | | | | |
Collapse
|
7
|
Vyas PM, Roychowdhury S, Woster PM, Svensson CK. Reactive oxygen species generation and its role in the differential cytotoxicity of the arylhydroxylamine metabolites of sulfamethoxazole and dapsone in normal human epidermal keratinocytes. Biochem Pharmacol 2005; 70:275-86. [PMID: 15894292 DOI: 10.1016/j.bcp.2005.04.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2005] [Revised: 04/20/2005] [Accepted: 04/20/2005] [Indexed: 11/17/2022]
Abstract
Cutaneous drug reactions (CDR) are responsible for numerous minor to life-threatening complications. Though the exact mechanism for CDR is not completely understood, evidence suggests that bioactivation of drugs to reactive oxygen or nitrogen species is an important factor in the initiation of these reactions. Several CDR-inducing drugs having an arylamine functional group, such as sulfamethoxazole (SMX) and dapsone (DDS), undergo bioactivation to reactive arylhydroxylamine metabolites. These metabolites can generate cellular oxidative stress by forming reactive oxygen species (ROS). Several studies have demonstrated a higher cytotoxicity with DDS hydroxylamine (DDS-NOH) compared to SMX hydroxylamine (SMX-NOH). To investigate the role of differential ROS generation in the higher cytotoxicity of DDS-NOH, hydroxylamine metabolites of SMX and DDS were synthesized and ROS formation by these metabolites determined. DDS-NOH and its analogues/metabolites consistently resulted in higher ROS formation as compared to SMX-NOH. However, comparison of the ROS generation and cytotoxicity of a series of arylhydroxylamine analogues of DDS did not support a simple correlation between ROS generation and cell death. Numerous ROS scavengers were found to reduce metabolite-induced ROS formation, with differences in the potency between the agents. The decrease in DDS-NOH-induced ROS generation in NHEK with ascorbic acid, N-acetylcysteine, Trolox, and melatonin was 87, 86, 44, and 16%, respectively. Similarly, the cytotoxicity and adduct formation of DDS-NOH in NHEK was reduced in the presence of ascorbic acid. In summary, these studies show that arylhydroxylamine metabolites of SMX/DDS induce ROS generation in NHEK, though such generation is not directly related to cytotoxicity.
Collapse
Affiliation(s)
- Piyush M Vyas
- Division of Pharmaceutics, College of Pharmacy, The University of Iowa, 115 S. Grand Avenue, S213 PHAR, Iowa City, IA 52242, USA
| | | | | | | |
Collapse
|
8
|
Hunter GA, Rivera E, Ferreira GC. Supraphysiological concentrations of 5-aminolevulinic acid dimerize in solution to produce superoxide radical anions via a protonated dihydropyrazine intermediate. Arch Biochem Biophys 2005; 437:128-37. [PMID: 15850552 DOI: 10.1016/j.abb.2005.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 03/09/2005] [Accepted: 03/10/2005] [Indexed: 12/01/2022]
Abstract
5-aminolevulinic acid (ALA) is the committed biological precursor to porphyrins. At supraphysiological concentrations ALA can dimerize to form 3,6-dihydropyrazine-2,5-dipropanoic acid (DHPY), which transfers electrons to XTT in a reaction that does not require metal ions and is specifically inhibited by superoxide dismutase. The formation of DHPY from ALA follows dimerization kinetics with a pK of 7.8+/-0.1. At pH 11.2, DHPY is relatively stable, but when the pH is dropped to 6.0 rapid conversion to 2,5-(beta-carboxyethyl)pyrazine occurs via an intermediate with an absorption maximum of 370 nm. Formation of this intermediate is pH-dependent with a pK of 6.0+/-0.1. These data indicate that ALA dimerizes to produce superoxide from a protonated form of DHPY. The significance of these results with respect to the concentrations of ALA used in photodynamic therapy, and the increased incidence of liver cancer in acute intermittent porphyria, is discussed.
Collapse
Affiliation(s)
- Gregory A Hunter
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
| | | | | |
Collapse
|
9
|
Onuki J, Almeida EA, Medeiros MHG, Di Mascio P. Inhibition of 5-aminolevulinic acid-induced DNA damage by melatonin, N1-acetyl-N2-formyl-5-methoxykynuramine, quercetin or resveratrol. J Pineal Res 2005; 38:107-15. [PMID: 15683465 DOI: 10.1111/j.1600-079x.2004.00180.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Porphyrias are defined as either inborn or acquired diseases related to enzymatic deficiencies in the heme biosynthetic pathway. Lead poisoning, hereditary tyrosinemia, and acute intermittent porphyria (AIP) are characterized by the absence of photosensitivity and the accumulation of 5-aminolevulinic acid (ALA) together with its increased urinary excretion. The main clinical manifestations of AIP are intermittent attacks of abdominal pain, neuromuscular weaknesses and neuropsychiatry alterations, and also an association with primary liver cancer, in which may be involved the oxidative potential of ALA which is able to cause DNA damage. The use of antioxidants in the treatment of ALA-induced oxidative stress is not well established. In the current work, we show the antioxidant efficacy of several compounds including melatonin, quercetin, resveratrol and N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), a melatonin oxidation product, in terms of their ability to limit DNA damage induced by ALA/Fe2+ in an in vitro system. Damage was measured by plasmid DNA strand breaks and detection of 8-oxo, 7-8-dihydro,2'-deoxyguanosine (8-oxodGuo) by high-performance liquid chromatography coupled with electrochemical detection. All compounds tested showed a dose-dependent protective action against free radical damage. These results could be the first step toward studies of the possible use of these antioxidants in oxidative stress promoted by ALA or other pro-oxidants.
Collapse
Affiliation(s)
- Janice Onuki
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | | | | | | |
Collapse
|
10
|
Juknat AA, Méndez MDVA, Quaglino A, Fameli CI, Mena M, Kotler ML. Melatonin prevents hydrogen peroxide-induced Bax expression in cultured rat astrocytes. J Pineal Res 2005; 38:84-92. [PMID: 15683462 DOI: 10.1111/j.1600-079x.2004.00166.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
During oxidative stress, cell apoptosis is promoted through the mitochondrial death pathway. Increased reactive oxygen species (ROS) are linked to excess cell loss and mediate the induction of apoptosis in various cell types. However, the role of ROS in the apoptotic pathway has not been clearly established. The aims of this study were to investigate the biochemical and morphological responses of rat astrocytes to hydrogen peroxide-mediated cell death and to define the role that melatonin might play in the apoptotic cascade. Hydrogen peroxide (H2O2; 0.1-1.0 mM) significantly reduced cell viability. Astrocyte death was associated with enhanced ROS production in a dose-dependent manner, as measured by 2',7'-dichloro-fluorescein fluorescence. H2O2-induced cell death was found to be mediated through an apoptotic pathway as treated cells exhibited cell shrinkage, nuclear condensation and marked DNA fragmentation. H2O2 also triggered caspase-3 activation and Bax expression. The ability of different antioxidants to prevent H2O2-induced apoptosis was examined by pre-incubating rat astrocytes with N-acetylcysteine (10 mM), glutathione (0.5 mM) or melatonin (0.1 mM and 10 nM). Results showed that N-acetylcysteine and glutathion can protect astrocytes against ROS accumulation and caspase-3 activation, whereas 0.1 mM melatonin can inhibit H2O2-induced apoptosis by regulating Bax expression and by inhibiting caspase-3 activation. Antiapoptotic effect of 10 nM melatonin associated to inhibition of Bax expression, give rise to new therapeutic approaches.
Collapse
Affiliation(s)
- Adela Ana Juknat
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
| | | | | | | | | | | |
Collapse
|
11
|
Abstract
The hepatic porphyrias are a group of rare metabolic disorders characterized by enzymatic defects in the biosynthesis of heme, a metalloporphyrin that is the principal product of porphyrin metabolism. The hepatic porphyrias are genetically transmitted as autosomal-dominant disorders with variable expression that produce a particularly severe form of neuropathy. Most medical students readily recognize acute attacks of porphyria when the classic triad of abdominal pain, psychosis, and neuropathy is present. Yet, porphyric neuropathy is a source of confusion in practice, and patients with porphyria rarely receive the correct diagnosis early in the course of the illness. Porphyric neuropathy is manifest by symptoms, signs, and cerebrospinal fluid abnormalities resembling acute Guillain-Barré syndrome. However, accompanying psychological features, a proximal predilection of asymmetric weakness, and electrodiagnostic findings indicative of an axonal polyradiculopathy or neuronopathy all suggest the diagnosis of porphyria. Confirmation of the diagnosis depends on use of appropriate laboratory studies. The underlying pathophysiology of porphyric neuropathy has not been established, but it may be related to direct neurotoxicity of elevated levels of delta-aminolevulinic acid. The severity of the neuropathy and the availability of potential treatments, including avoidance of provocative factors, make identification important.
Collapse
Affiliation(s)
- James W Albers
- Department of Neurology, 1C325/0032 University Hospital, University of Michigan Health System, 1500 East Medical Center Drive, Ann Arbor 48109-0032, USA.
| | | |
Collapse
|