In vitro kainate injury to large, SMI-32(+) spinal neurons is Ca2+ dependent.
The non-phosphorylated neurofilament marker, SMI-32, identifies ventral horn motor neurons in spinal cord slice. We show here that SMI-32 marks a subset of spinal cord neurons in culture. Many of these neurons ('large SMI-32(+) neurons') have morphological characteristics of identified motor neurons in vitro: large cell body size (> 20 microns), extensive neuritic arborization and, generally, one particularly long process. These neurons are preferentially injured by brief (40 min) kainate exposures, but not by NMDA exposures. This rapidly triggered damage to large SMI-32(+) neurons is Ca2+ dependent. In addition, most of the SMI-32(+) neurons exhibit kainate-stimulated Co2+ uptake, a histochemical technique which marks neurons possessing Ca(2+)-permeable AMPA/kainate receptor-gated channels. The unusual vulnerability of large SMI-32(+) spinal neurons to kainate toxicity may result from rapid Ca2+ entry through Ca(2+)-permeable AMPA/kainate channels.
Carriedo
S G
SG
Department of Neurology, University of California Irvine 92717-4290, USA.
Yin
H Z
HZ
Lamberta
R
R
Weiss
J H
JH
D000818:Animals; D015415:Biomarkers; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D003035:Cobalt; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000633:toxicity*; D051379:Mice; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism; D016202:N-Methylaspartate / Q000633:toxicity; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018091:Receptors, AMPA / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism
D015415:Biomarkers; D015220:Calcium Channels; D016900:Neurofilament Proteins; D018091:Receptors, AMPA; D003035:Cobalt; D016202:N-Methylaspartate; D007608:Kainic Acid; D002118:Calcium