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| TR |
TITLE |
AUTHORS |
KEYWORDS |
MATERIALS & METHODS
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MICROSCOPIC
TECHNIQUES |
SPECIES |
MORPHOLOGY |
CELL
LINE |
| 628 |
Motor
Neurons Are Selectively Vulnerable to AMPA/Kainate
Receptor-Mediated Injury In Vitro |
Sean
G. Carriedo, Hong Z. Yin, and John H. Weiss |
cell
culture, AMPA, kainate, glutamate, motor
neuron, calcium, SMI-32, peripherin, ChAT, neurotoxicity, cobalt, calcium imaging |
For Ca21 imaging studies, cultures
were prepared as described above except that cells were plated on poly-L-lysine-coated glass-bottomed
plates (Plastek Cultureware,Ashland, MA).
|
inverted
fluorescence microscopy, phase-contrast microscopy |
mouse |
neuronal |
Mixed
spinal cord cultures |
| |
The nonphosphorylated neurofilament marker SMI-32
stains motor neurons in spinal cord slices and stains a subset of cultured spinal neurons [“large
SMI-32(1) neurons”], which have a morphology consistent with motor neurons identified in
vitro: large cell body, long axon, and extensive dendritic arborization. They are found preferentially
in ventral spinal cord cultures, providing further evidence that large SMI-32(1) neurons are
indeed motor neurons, and SMI-32 staining often colocalizes with established motor neuron markers
(including acetylcholine, calcitonin gene-related peptide, and peripherin). Additionally, choline
acetyltransferase activity (a frequently used index of the motor neuron population) and peripherin(1)
neurons share with large SMI-32(1) neurons an unusual vulnerability to AMPA/kainate receptor-mediated
injury. Kainateinduced loss of these motor neuron markers is Ca21- dependent, which supports
a critical role of Ca21 ions in this injury. Raising extracellular Ca21 exacerbates injury,
whereas removal of extracellular Ca21 is protective. A basis for this vulnerability is provided
by the observation that most peripherin( 1) neurons, like large SMI-32(1) neurons, are subject
to kainate-stimulated Co21 uptake, a histochemical stain that identifies neurons possessing
Ca21-permeable AMPA/kainate receptor-gated channels. Finally, of possibly greater relevance
to the slow motor neuronal degeneration in diseases, both large SMI-32(1) neurons and peripherin(1)
neurons are selectively damaged by prolonged (24 hr) low-level exposures to kainate (10 mM)
or to the glutamate reuptake blocker L-transpyrrolidine- 2,4-dicarboxylic acid (100 mM). During
these lowlevel kainate exposures, large SMI-32(1) neurons showed higher intracellular Ca21 concentrations
than most spinal neurons, suggesting that Ca21 ions are also important in this more slowly evolving
injury. |
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