TY - JOUR
T1 - Glia modulate the response of murine cortical neurons to excitotoxicity
T2 - Glia exacerbate AMPA neurotoxicity
AU - Dugan, L. L.
AU - Bruno, V. M G
AU - Amagasu, S. M.
AU - Giffard, R. G.
PY - 1995
Y1 - 1995
N2 - We have developed 'pure' neuronal cultures (<1% astrocytes) from mouse neocortex to study the effect of glial cells on the response of neurons to injury. Cortical neurons were found to require glial-conditioned medium to survive. Immature neurons, 2-4 d in vitro, deprived of glial-conditioned medium, underwent apoptosis over 48 hr, as suggested by condensed nuclear morphology, DNA fragmentation, and protection by inhibition of macromolecular synthesis. Apoptosis induced by trophic factor deprivation has been described for other neuronal populations, such as superior cervical ganglion and dorsal root ganglion cells. Cortical neurons in pure culture provide another neuronal population for the study of apoptosis induced by trophic factor deprivation. We then studied the interaction of neurons and glia under excitotoxic conditions, Experiments on mature cultures showed that pure neuronal cultures were at least 10-fold more sensitive to acute glutamate exposure than were neuronal-glial ('mixed') cocultures. The difference in sensitivity between pure neurons and mixed cultures was reduced when mixed cultures were treated with the glutamate uptake inhibitor, L-trans- pyrrolidine-2,4-dicarboxylic acid (trans-PDC). In 24 hr exposure to N- methyl-D-aspartate (NMDA), or oxygen, glucose deprivation, pure neurons were more sensitive than mixed cultures; trans-PDC again increased the sensitivity of mixed cultures to nearly that of pure neuronal cultures. In contrast, mixed and pure neuronal cultures exposed to NMDA for 10 min, or to kainate for 24 hr, had similar injury dose-response curves, suggesting that glial glutamate uptake is a less important protective mechanism in these excitotoxic injuries. Surprisingly, pure neurons were less sensitive than mixed cultures to (RS)-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) toxicity at concentrations up to 100 μM. This does not reflect astrocyte toxicity, as AMPA at concentrations to 1 mM did not injure astrocyte cultures. Glial cultures showed increased levels of glutamate in the extracellular medium in response to exposure to AMPA, but not NMDA or kainate. However, pure neuronal and mixed cultures exposed to the same concentration of AMPA did not have elevated levels of glutamate in the media. We found that gila were generally neuroprotective under excitotoxic conditions, likely through their ability to clear extracellular glutamate. However, the presence of gila exacerbated AMPA neurotoxicity.
AB - We have developed 'pure' neuronal cultures (<1% astrocytes) from mouse neocortex to study the effect of glial cells on the response of neurons to injury. Cortical neurons were found to require glial-conditioned medium to survive. Immature neurons, 2-4 d in vitro, deprived of glial-conditioned medium, underwent apoptosis over 48 hr, as suggested by condensed nuclear morphology, DNA fragmentation, and protection by inhibition of macromolecular synthesis. Apoptosis induced by trophic factor deprivation has been described for other neuronal populations, such as superior cervical ganglion and dorsal root ganglion cells. Cortical neurons in pure culture provide another neuronal population for the study of apoptosis induced by trophic factor deprivation. We then studied the interaction of neurons and glia under excitotoxic conditions, Experiments on mature cultures showed that pure neuronal cultures were at least 10-fold more sensitive to acute glutamate exposure than were neuronal-glial ('mixed') cocultures. The difference in sensitivity between pure neurons and mixed cultures was reduced when mixed cultures were treated with the glutamate uptake inhibitor, L-trans- pyrrolidine-2,4-dicarboxylic acid (trans-PDC). In 24 hr exposure to N- methyl-D-aspartate (NMDA), or oxygen, glucose deprivation, pure neurons were more sensitive than mixed cultures; trans-PDC again increased the sensitivity of mixed cultures to nearly that of pure neuronal cultures. In contrast, mixed and pure neuronal cultures exposed to NMDA for 10 min, or to kainate for 24 hr, had similar injury dose-response curves, suggesting that glial glutamate uptake is a less important protective mechanism in these excitotoxic injuries. Surprisingly, pure neurons were less sensitive than mixed cultures to (RS)-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) toxicity at concentrations up to 100 μM. This does not reflect astrocyte toxicity, as AMPA at concentrations to 1 mM did not injure astrocyte cultures. Glial cultures showed increased levels of glutamate in the extracellular medium in response to exposure to AMPA, but not NMDA or kainate. However, pure neuronal and mixed cultures exposed to the same concentration of AMPA did not have elevated levels of glutamate in the media. We found that gila were generally neuroprotective under excitotoxic conditions, likely through their ability to clear extracellular glutamate. However, the presence of gila exacerbated AMPA neurotoxicity.
KW - AMPA
KW - astrocytes
KW - cell culture
KW - glutamate
KW - ischemia
KW - kainate
KW - neocortex
KW - NMDA
UR - http://www.scopus.com/inward/record.url?scp=0029055091&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029055091&partnerID=8YFLogxK
M3 - Article
C2 - 7540679
AN - SCOPUS:0029055091
VL - 15
SP - 4545
EP - 4555
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 6
ER -