H(2)O(2)-mediated modulation of cytosolic signaling and organelle function in rat hippocampus.
Reactive oxygen species (ROS) released from (dys-)functioning mitochondria contribute to normal and pathophysiological cellular signaling by modulating cytosolic redox state and redox-sensitive proteins. To identify putative redox targets involved in such signaling, we exposed hippocampal neurons to hydrogen peroxide (H(2)O(2)). Redox-sensitive dyes indicated that externally applied H(2)O(2) may oxidize intracellular targets in cell cultures and acute tissue slices. In cultured neurons, H(2)O(2) (EC(50) 118 microM) induced an intracellular Ca(2+) rise which could still be evoked upon Ca(2+) withdrawal and mitochondrial uncoupling. It was, however, antagonized by thapsigargin, dantrolene, 2-aminoethoxydiphenyl borate, and high levels of ryanodine, which identifies the endoplasmic reticulum (ER) as the intracellular Ca(2+) store involved. Intracellular accumulation of endogenously generated H(2)O(2)-provoked by inhibiting glutathione peroxidase-also released Ca(2+) from the ER, as did extracellular generation of superoxide. Phospholipase C (PLC)-mediated metabotropic signaling was depressed in the presence of H(2)O(2), but cytosolic cyclic adenosine-5'-monophosphate (cAMP) levels were not affected. H(2)O(2) (0.2-5 mM) moderately depolarized mitochondria, halted their intracellular trafficking in a Ca(2+)- and cAMP-independent manner, and directly oxidized cellular nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH(2)). In part, the mitochondrial depolarization reflects uptake of Ca(2+) previously released from the ER. We conclude that H(2)O(2) releases Ca(2+) from the ER via both ryanodine and inositol trisphosphate receptors. Mitochondrial function is not markedly impaired even by millimolar concentrations of H(2)O(2). Such modulation of Ca(2+) signaling and organelle interaction by ROS affects the efficacy of PLC-mediated metabotropic signaling and may contribute to the adjustment of neuronal function to redox conditions and metabolic supply.
Gerich
Florian J
FJ
DFG Research Center Molecular Physiology of the Brain (CMPB), Zentrum für Physiologie und Pathophysiologie, Abteilung Neuro- und Sinnesphysiologie, Georg-August-Universität Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
Funke
Frank
F
Hildebrandt
Belinda
B
Fasshauer
Martin
M
Müller
Michael
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001370:Axonal Transport / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000037:antagonists & inhibitors; D007700:Kinetics; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009068:Movement / Q000187:drug effects; D009243:NAD / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015388:Organelles / Q000187:drug effects / Q000502:physiology*; D010084:Oxidation-Reduction / Q000187:drug effects; D058910:Purinergic P2 Receptor Agonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12
D002121:Calcium Channel Blockers; D053496:Inositol 1,4,5-Trisphosphate Receptors; C553058:P2ry12 protein, rat; D058910:Purinergic P2 Receptor Agonists; D017382:Reactive Oxygen Species; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide