title: Antioxidant Protection of NADPH-Depleted Oligodendrocyte Precursor Cells Is Dependent on Supply of Reduced Glutathione.
abstract: The pentose phosphate pathway is the main source of NADPH, which by reducing oxidized glutathione, contributes to antioxidant defenses. Although oxidative stress plays a major role in white matter injury, significance of NADPH for oligodendrocyte survival has not been yet investigated. It is reported here that the NADPH antimetabolite 6-amino-NADP (6AN) was cytotoxic to cultured adult rat spinal cord oligodendrocyte precursor cells (OPCs) as well as OPC-derived oligodendrocytes. The 6AN-induced necrosis was preceded by increased production of superoxide, NADPH depletion, and lower supply of reduced glutathione. Moreover, survival of NADPH-depleted OPCs was improved by the antioxidant drug trolox. Such cells were also protected by physiological concentrations of the neurosteroid dehydroepiandrosterone (10(-8) M). The protection by dehydroepiandrosterone was associated with restoration of reduced glutathione, but not NADPH, and was sensitive to inhibition of glutathione synthesis. A similar protective mechanism was engaged by the cAMP activator forskolin or the G protein-coupled estrogen receptor (GPER/GPR30) ligand G1. Finally, treatment with the glutathione precursor N-acetyl cysteine reduced cytotoxicity of 6AN. Taken together, NADPH is critical for survival of OPCs by supporting their antioxidant defenses. Consequently, injury-associated inhibition of the pentose phosphate pathway may be detrimental for the myelination or remyelination potential of the white matter. Conversely, steroid hormones and cAMP activators may promote survival of NADPH-deprived OPCs by increasing a NADPH-independent supply of reduced glutathione. Therefore, maintenance of glutathione homeostasis appears as a critical effector mechanism for OPC protection against NADPH depletion and preservation of the regenerative potential of the injured white matter.
authors.affiliation: Kentucky Spinal Cord Injury Research Center, University of Louisville, KY, USA Department of Neurological Surgery, University of Louisville, KY, USA.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kilanczyk
authors.affiliation: Kentucky Spinal Cord Injury Research Center, University of Louisville, KY, USA Department of Neurological Surgery, University of Louisville, KY, USA.
authors.forename: Sujata
authors.initials: S
authors.lastname: Saraswat Ohri
authors.affiliation: Kentucky Spinal Cord Injury Research Center, University of Louisville, KY, USA Department of Neurological Surgery, University of Louisville, KY, USA Department of Anatomical Sciences and Neurobiology, University of Louisville, KY, USA.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Whittemore
authors.affiliation: Kentucky Spinal Cord Injury Research Center, University of Louisville, KY, USA Department of Neurological Surgery, University of Louisville, KY, USA Department of Pharmacology and Toxicology, University of Louisville, KY, USA michal.hetman@louisville.edu.
authors.forename: Michal
authors.initials: M
authors.lastname: Hetman
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000633:toxicity; D000975:Antioxidants / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003687:Dehydroepiandrosterone / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009243:NAD / Q000031:analogs & derivatives / Q000633:toxicity; D009249:NADP / Q000276:immunology / Q000378:metabolism*; D009836:Oligodendroglia / Q000187:drug effects*; D051381:Rats; D013116:Spinal Cord / Q000166:cytology; D013234:Stem Cells / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors
chemical_list: D000276:Adjuvants, Immunologic; D000906:Antibodies; D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; D009243:NAD; D013481:Superoxides; D003687:Dehydroepiandrosterone; D009249:NADP; C011646:6-amino-NAD; D007770:L-Lactate Dehydrogenase; D053148:Caspase 3; D005978:Glutathione
keywords: demyelination; metabolism; oligodendrocytes; oxidative stress; pentose phosphate pathway; white matter