Glutamate receptor expression and chronic glutamate toxicity in rat motor cortex.
In addition to the loss of spinal motor neurons, amyotrophic lateral sclerosis (ALS) is also associated with degeneration of corticospinal layer V pyramidal neurons and decreased glutamate transport in the cortex. We characterized the glutamate receptors on corticospinal neurons in acutely isolated rat motor cortex slices and found that the synaptic inputs to the corticospinal layer V neurons had a lesser proportional contribution from NMDA receptors relative to AMPA receptors than did layer II/III pyramidal neurons. The synaptic I(AMPA) was also more inwardly rectified, indicating a greater Ca(2+)-permeable component, in layer V. In a cortical organotypic slice culture model, blockade of glutamate transporters elevated glutamate in the media and led to pyramidal neuron loss in both layers. The loss of layer V pyramidal neurons was attenuated by antagonists of AMPA/kainate or Ca(2+)-permeable AMPA receptors, suggesting their therapeutic potential in the protection of the motor cortex in ALS.
Young
Kate C
KC
Department of Neurology, 5841 S. Maryland Ave, MC2030, Chicago, IL 60637, USA.
McGehee
Daniel S
DS
Brorson
James R
JR
D000818:Animals; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004558:Electric Stimulation; D004594:Electrophysiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000633:toxicity*; D008314:Malonates / Q000633:toxicity; D009044:Motor Cortex / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D016202:N-Methylaspartate / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000494:pharmacology; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000187:drug effects / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism; D017470:Receptors, Glutamate / Q000096:biosynthesis*; D019782:Riluzole / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D008314:Malonates; D018696:Neuroprotective Agents; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D018698:Glutamic Acid; D016202:N-Methylaspartate; D019782:Riluzole; C030290:malonic acid; D002118:Calcium