Cerebral cortical neuron apoptosis after mild excitotoxic injury in vitro: different roles of mesencephalic and cortical astrocytes.
OBJECTIVE
Increasing evidence supports the presence of neuronal apoptosis after ischemic or excitotoxic brain injury. Astrocytes, which exhibit significant regional differences in function, may exert a protective effect on neurons exposed to ischemic injury. We examined the effects of astrocytes derived from different regions of the central nervous system on neuronal apoptosis after mild excitotoxic injury in tissue culture.


METHODS
Purified astrocyte cultures derived from P4 rat cerebral cortex or mesencephalon showed transient cell swelling but no cell death when exposed to 50 micromol/L glutamate for 5 minutes. When mixed neuronal/glial cocultures were exposed to the same glutamate dose, neuron death was observed. Necrotic and apoptotic cell death during 24 hours was examined using morphological criteria, nuclear staining, triphosphate nick end labeling, and trypan blue exclusion.


RESULTS
We found that cortical neurons that elaborate a more extensive dendritic arbor when grown on homotypic astrocytes are more likely to undergo apoptosis than neurons with a limited dendritic arbor grown on heterotypic astrocytes. By contrast, a similar number of neurons undergo necrotic cell death.


CONCLUSIONS
This finding may be associated with 1) increased vulnerability of neurons with a more elaborate dendrite structure to mild excitotoxic injury, or 2) regional differences in the ability of astrocytes to attenuate apoptosis.
Huang
P P
PP
Department of Neurosurgery, New York University Medical Center, and The New York Veterans Affairs Medical Center, 10016, USA.
Esquenazi
S
S
Le Roux
P D
PD
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000187:drug effects*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000473:pathology; D046508:Culture Techniques; D003712:Dendrites / Q000187:drug effects / Q000473:pathology; D018698:Glutamic Acid / Q000633:toxicity*; D006801:Humans; D008636:Mesencephalon / Q000187:drug effects* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D009474:Neurons / Q000187:drug effects / Q000473:pathology; D051381:Rats
D018698:Glutamic Acid