Peroxynitrite and nitric oxide donors induce neuronal apoptosis by eliciting autocrine excitotoxicity.
Endogenous generation of nitric oxide and its congeners, including peroxynitrite (ONOO-), has been implicated in the mechanism of neuron loss in neurodegenerative diseases. Accordingly, nitric oxide donors and ONOO- can elicit both apoptosis and necrosis in neuron cultures. Here we show that nitric oxide donors and ONOO- are each able to trigger apoptosis of mouse cerebellar granule cells by an excitotoxic mechanism requiring exocytosis and NMDA receptor-mediated intracellular Ca2+ overload. This conclusion is supported by the following findings. Apoptosis was induced by various nitric oxide donors or by direct addition of ONOO- to differentiated cerebellar granule cell cultures that were sensitive to NMDA toxicity, but not in cerebellar granule cells that did not display NMDA-induced cell death (i.e. early days in culture) or in various glial cell populations. Donors of ONOO- or nitric oxide stimulated a sustained increase in intracellular Ca2+, which was prevented by inhibitors of NMDA receptors, such as MK-801 and 5-phospho-aminovaleric acid, or by dampening neuronal electrical activity with high concentrations of extracellular Mg2+. Moreover, these treatments and the exposure of cerebellar granule cells in nominally Ca2+-free media prevented apoptotic cell death. Both the intracellular Ca2+ increase and apoptosis elicited by ONOO- or the nitric oxide donors were prevented by blocking exocytosis with tetanus toxin or botulinum neurotoxin C.
Leist
M
M
Faculty of Biology, University of Konstanz, Germany.
Fava
E
E
Montecucco
C
C
Nicotera
P
P
D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D006728:Hormones / Q000502:physiology*; D007425:Intracellular Membranes / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009498:Neurotoxins / Q000378:metabolism*; D009566:Nitrates / Q000494:pharmacology*; D009569:Nitric Oxide / Q000494:pharmacology*; D009994:Osmolar Concentration; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D026403:S-Nitrosothiols
D006728:Hormones; D009498:Neurotoxins; D009566:Nitrates; D016194:Receptors, N-Methyl-D-Aspartate; D026403:S-Nitrosothiols; C039642:peroxynitric acid; D009569:Nitric Oxide; C021315:S-nitrosocysteine; D003545:Cysteine; D002118:Calcium