Mitochondrial permeability transition and calcium dynamics in striatal neurons upon intense NMDA receptor activation.
Deregulation of the intracellular Ca2+ homeostasis by NMDA receptor activation leads to neuronal cell death. Induction of the mitochondrial permeability transition pore (MPT) by Ca2+ is a critical event in mediating cell death. In this study, we used fluorescent Ca2+ indicators to investigate the effect of high concentrations of NMDA on cytosolic and mitochondrial Ca2+ concentrations ([Ca2+]c and [Ca2+]m, respectively) in cultured striatal neurons. Exposure to NMDA resulted in an immediate, sustained increase in [Ca2+]c followed by a secondary increase in [Ca2+]c. This second increase of [Ca2+]c was prevented by pretreatment with N-methyl-valine-4-cyclosporin (NMV-Cys). Exposure of neurons to NMDA also resulted in an increase in [Ca2+]m that was followed by a precipitous decrease in the rhod-2 signal. This decrease followed the time frame of the secondary increase in [Ca2+]c. Preincubation of the neurons with NMV-Cys prevented the decrease in rhod-2 fluorescence. These dynamic changes in the rhod-2 signal and [Ca2+]m in response to NMDA were confirmed by using confocal microscopy. The presented results indicate that MPT can be detected in living neurons using fluorescent Ca2+ indicators, which would allow the study of the physiological role of MPT in cell death.
Alano
Conrad C
CC
Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, New York 14642, USA.
Beutner
Gisela
G
Dirksen
Robert T
RT
Gross
Robert A
RA
Sheu
Shey-Shing
SS
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000166:cytology*; D016572:Cyclosporine / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D016194:Receptors, N-Methyl-D-Aspartate; C101294:N-methyl-valyl-4-cyclosporin A; D016202:N-Methylaspartate; D016572:Cyclosporine; D002118:Calcium