Plasticity in alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunits in the rat dorsal horn following deafferentation.
Immunostaining for GluR1 and GluR2/3 subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor is prominent in laminae I and II of the normal dorsal horn, with much less staining in deeper laminae. Three days after dorsal rhizotomy, image analysis demonstrates a significant decrease in staining density for both antibodies in the superficial dorsal horn. By contrast, staining density is significantly increased in laminae III, IV and the reticulated region of lamina V for GluR1 only. This increase suggests that AMPA receptors contribute to deafferentation or radicular pain by at least two mechanisms: (1) up-regulation of GluR1 subunits of the AMPA receptor in deeper laminae, and (2) enhanced Ca2+ permeability of dorsal horn neurons because AMPA receptors lacking the GluR2 subunit are Ca2+ permeable. Glutamate activation of these receptors could initiate or potentiate second messenger cascades that could well contribute to neuronal changes documented in the dorsal horn of deafferented animals.
Carlton
S M
SM
Department of Anatomy and Neuroscience, Marine Biomedical Institute, University of Texas Medical Branch, Galveston 77555-1069, USA. smcarlto@utmb.edu
Hargett
G L
GL
Coggeshall
R E
RE
D000818:Animals; D007150:Immunohistochemistry; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D009475:Neurons, Afferent / Q000737:chemistry / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000032:analysis* / Q000502:physiology; D019051:Rhizotomy; D013116:Spinal Cord / Q000737:chemistry / Q000502:physiology*; D013376:Substantia Gelatinosa / Q000502:physiology
D018091:Receptors, AMPA