Degeneration of cultured cortical neurons following prolonged inactivation: molecular mechanisms.
Networks of neurons express persistent spontaneous network activity when maintained in dissociated cultures. Prolonged blockade of the spontaneous activity with tetrodotoxin (TTX) causes the eventual death of the neurons. In this study, we investigated some molecular mechanisms that may underlie the activity-suppressed slow degeneration of cortical neurons in culture. Already after 3-4 days of exposure to TTX, well before the neurons die, they began to express markers that lead to their eventual death, 7-10 days later. There was a reduction in glutamate receptor (GluR2) expression, a persistent increase in intracellular calcium concentration, activation of calpain, and an increase in spectrin breakdown products. At this point, blockade of GluR2-lacking GluR1 or calpain (either with a selective antagonist or through the natural regulator of calpain, calpastatin), protected cells from the toxic action of TTX. Subsequently, mitochondria lost their normal elongated shape as well as their membrane potential. Eventually, neurons activated caspase 3 and PUMA (p53 up-regulated modulator of apoptosis), hallmarks of neuronal apoptosis, and died. These experiments will lead to a better understanding of slow neuronal death, typical of neurodegenerative diseases.
Schonfeld-Dado
Eldi
E
Department of Neurobiology, The Weizmann Institute, Rehovot, Israel.
Fishbein
Ianai
I
Segal
Menahem
M
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002154:Calpain / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000378:metabolism* / Q000503:physiopathology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D028361:Mitochondrial Diseases / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D009410:Nerve Degeneration / Q000378:metabolism* / Q000503:physiopathology; D009415:Nerve Net / Q000378:metabolism / Q000503:physiopathology; D009434:Neural Pathways / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D026941:Sodium Channel Blockers / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D026941:Sodium Channel Blockers; D013779:Tetrodotoxin; D002154:Calpain; D002118:Calcium