Ammonia prevents glutamate-induced but not low K(+)-induced apoptosis in cerebellar neurons in culture

Neuroscience. 2003;117(4):899-907. doi: 10.1016/s0306-4522(02)00957-0.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonia / metabolism*
  • Ammonia / pharmacology
  • Animals
  • Animals, Newborn
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Calcium / metabolism
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology
  • Caspase 3
  • Caspases / drug effects
  • Caspases / metabolism
  • Cells, Cultured
  • Cerebellar Cortex / cytology
  • Cerebellar Cortex / drug effects
  • Cerebellar Cortex / metabolism*
  • Cytochrome c Group / metabolism
  • Drug Administration Schedule
  • Drug Interactions / physiology
  • Glutamic Acid / metabolism*
  • Glutamic Acid / pharmacology
  • Hyperammonemia / metabolism
  • Hyperammonemia / physiopathology
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Neurons / drug effects
  • Neurons / metabolism*
  • Potassium Deficiency / metabolism*
  • Potassium Deficiency / physiopathology
  • Rats
  • Rats, Wistar
  • Receptors, N-Methyl-D-Aspartate / drug effects
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Up-Regulation / drug effects
  • Up-Regulation / physiology

Substances

  • Cytochrome c Group
  • Receptors, N-Methyl-D-Aspartate
  • Glutamic Acid
  • Ammonia
  • Casp3 protein, rat
  • Caspase 3
  • Caspases
  • Calcium