Glutamate mobilizes [Zn2+] through Ca2+ -dependent reactive oxygen species accumulation.
Liberation of zinc from intracellular stores contributes to oxidant-induced neuronal injury. However, little is known regarding how endogenous oxidant systems regulate intracellular free zinc ([Zn(2+)](i)). Here we simultaneously imaged [Ca(2+)](i) and [Zn(2+)](i) to study acute [Zn(2+)](i) changes in cultured rat forebrain neurons after glutamate receptor activation. Neurons were loaded with fura-2FF and FluoZin-3 to follow [Ca(2+)](i) and [Zn(2+)](i), respectively. Neurons treated with glutamate (100 microM) for 10 min gave large Ca(2+) responses that did not recover after termination of the glutamate stimulus. Glutamate also increased [Zn(2+)](i), however glutamate-induced [Zn(2+)](i) changes were completely dependent on Ca(2+) entry, appeared to arise entirely from internal stores, and were substantially reduced by co-application of the membrane-permeant chelator TPEN during the glutamate treatment. Pharmacological maneuvers revealed that a number of endogenous oxidant producing systems, including nitric oxide synthase, phospholipase A(2), and mitochondria all contributed to glutamate-induced [Zn(2+)](i) changes. We found no evidence that mitochondria buffered [Zn(2+)](i) during acute glutamate receptor activation. We conclude that glutamate-induced [Zn(2+)](i) transients are caused in part by [Ca(2+)](i)-induced reactive oxygen species that arises from both cytosolic and mitochondrial sources.
Dineley
Kirk E
KE
Department of Biology, Francis Marion University, Florence, SC, USA.
Devinney
Michael J
MJ
Zeak
Jennifer A
JA
Rintoul
Gordon L
GL
Reynolds
Ian J
IJ
D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes; D016257:Fura-2; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009410:Nerve Degeneration / Q000378:metabolism* / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D016877:Oxidants / Q000096:biosynthesis; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D011083:Polycyclic Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000187:drug effects / Q000378:metabolism; D015032:Zinc / Q000378:metabolism* / Q000494:pharmacology
D002614:Chelating Agents; C451182:FluoZin-3; D005456:Fluorescent Dyes; D016877:Oxidants; D011083:Polycyclic Compounds; D017382:Reactive Oxygen Species; D017470:Receptors, Glutamate; D018698:Glutamic Acid; D015032:Zinc; D002118:Calcium; D016257:Fura-2