Ammonia prevents glutamate-induced but not low K(+)-induced apoptosis in cerebellar neurons in culture.
Cultured rat cerebellar granule neurons are widely used as a model system for studying neuronal apoptosis. Either low K(+) (5 mM) or low concentrations of glutamate (1-10 microM) induce apoptosis in cerebellar neurons in culture. However, the molecular mechanism(s) involved remain unclear. We show that long-term treatment with ammonia prevents glutamate-induced but not low K(+)-induced apoptosis in cerebellar neurons, as assessed by measuring DNA fragmentation and activation of caspase 3. Ammonia prevented glutamate-induced increase of intracellular calcium, depolarization of the inner mitochondrial membrane, release of cytochrome c to the cytosol, activation of caspase 3 and fragmentation of DNA. However, ammonia did not prevent low K(+)-induced activation of caspase 3 and fragmentation of DNA. These results indicate that the initial steps involved in the induction of apoptosis by low K(+) or by glutamate are different and that ammonia prevents glutamate-induced apoptosis by reducing glutamate-induced rise of intracellular Ca(2+), thus avoiding the activation of subsequent events of the apoptotic process.
Llansola
M
M
Laboratorio de Neurobiología, Instituto de Investigaciones Citológicas de la FVIB, Amadeo de Saboya, 4 46010, Valencia, Spain.
Boscá
L
L
Felipo
V
V
Hortelano
S
S
D000641:Ammonia / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D053148:Caspase 3; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002525:Cerebellar Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003574:Cytochrome c Group / Q000378:metabolism; D004334:Drug Administration Schedule; D004347:Drug Interactions / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D022124:Hyperammonemia / Q000378:metabolism / Q000503:physiopathology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011191:Potassium Deficiency / Q000378:metabolism* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D003574:Cytochrome c Group; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D000641:Ammonia; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D002118:Calcium