Mitochondrial and extramitochondrial apoptotic signaling pathways in cerebrocortical neurons

Proc Natl Acad Sci U S A. 2000 May 23;97(11):6161-6. doi: 10.1073/pnas.100121097.


In cultured cerebrocortical neurons, mild excitotoxic insults or staurosporine result in apoptosis. We show here that N-methyl-d-aspartate (NMDA) receptor-mediated, but not staurosporine-mediated, apoptosis is preceded by depolarization of the mitochondrial membrane potential (Deltapsi(m)) and ATP loss. Both insults, however, release cytochrome c (Cyt c) into the cytoplasm. What prompts mitochondria to release Cyt c and the mechanism of release are as yet unknown. We examined the effect of inhibition of the adenine nucleotide translocator (ANT), a putative component of the mitochondrial permeability transition pore. Inhibition of the mitochondrial ANT with bongkrekic acid (BA) prevented NMDA receptor-mediated apoptosis of cerebrocortical neurons. Concomitantly, BA prevented Deltapsi(m) depolarization, promoted recovery of cellular ATP content, and blocked caspase-3 activation. However, in the presence of BA, Cyt c was still released. Because BA prevented NMDA-induced caspase-3 activation and apoptosis, the presence of Cyt c in the neuronal cytoplasm is not sufficient for the induction of caspase activity or apoptosis. In contrast to these findings, BA was ineffective in preventing staurosporine-induced activation of caspases or apoptosis. Additionally, staurosporine-induced, but not NMDA-induced, apoptosis was associated with activation of caspase-8. These results indicate that, in cerebrocortical cultures, excessive NMDA receptor activation precipitates neuronal apoptosis by means of mitochondrial dysfunction, whereas staurosporine utilizes a distinct pathway.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Bongkrekic Acid / pharmacology
  • Caspase 3
  • Caspase 8
  • Caspase 9
  • Caspases / metabolism
  • Cerebral Cortex / cytology*
  • Cytochrome c Group / physiology
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Intracellular Membranes / metabolism
  • Mitochondria / enzymology
  • Mitochondria / physiology*
  • Mitochondrial ADP, ATP Translocases / antagonists & inhibitors
  • Mitochondrial ADP, ATP Translocases / physiology
  • Nerve Tissue Proteins / antagonists & inhibitors
  • Nerve Tissue Proteins / physiology
  • Neurons / cytology*
  • Neurons / drug effects
  • Permeability
  • Protein Kinase Inhibitors
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Staurosporine / pharmacology


  • Cytochrome c Group
  • Enzyme Inhibitors
  • Nerve Tissue Proteins
  • Protein Kinase Inhibitors
  • Receptors, N-Methyl-D-Aspartate
  • Bongkrekic Acid
  • Adenosine Triphosphate
  • Mitochondrial ADP, ATP Translocases
  • Caspase 3
  • Caspase 8
  • Caspase 9
  • Caspases
  • Staurosporine