Calpain activation and Na+/Ca2+ exchanger degradation occur downstream of calcium deregulation in hippocampal neurons exposed to excitotoxic glutamate

Tatiana Brustovetsky, Alexey Bolshakov, Nickolay Brustovetsky

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Delayed calcium deregulation (DCD) plays an essential role in glutamate excitotoxicity, a major detrimental factor in stroke, traumatic brain injury, and various neurodegenerations. In the present study, we examined the role of calpain activation and Na+/Ca2+ exchanger (NCX) degradation in DCD and excitotoxic cell death in cultured hippocampal neurons. Exposure of neurons to glutamate caused DCD accompanied by secondary mitochondrial depolarization. Activation of calpain was evidenced by detecting NCX isoform 3 (NCX3) degradation products. Degradation of NCX isoform 1 (NCX1) was below the detection limit of Western blotting. Degradation of NCX3 was detected only after 1 hr of incubation with glutamate, whereas DCD occurred on average within 15 min after glutamate application. Calpeptin, an inhibitor of calpain, significantly attenuated NCX3 degradation but failed to inhibit DCD and excitotoxic neuronal death. Calpain inhibitors I, III, and VI also failed to influence DCD and glutamate-induced neuronal death. On the other hand, MK801, an inhibitor of the NMDA subtype of glutamate receptors, added shortly after the initial glutamate-induced jump in cytosolic Ca2+, completely prevented DCD and activation of calpain and strongly protected neurons against excitotoxicity. Taken together, our results suggest that, in glutamate-treated hippocampal neurons, the initial increase in cytosolic Ca2+ that precedes DCD is insuffi-cient for sustained calpain activation, which most likely occurs downstream of DCD.

Original languageEnglish (US)
Pages (from-to)1317-1328
Number of pages12
JournalJournal of Neuroscience Research
Volume88
Issue number6
DOIs
StatePublished - May 1 2010

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Keywords

  • Calcium
  • Calpain
  • Calpeptin
  • Excitotoxicity
  • Glutamate
  • Neuron

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience

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