Effects of peripheral nerve injuries and tissue inflammation on the levels of neuropeptide Y-like immunoreactivity in rat primary afferent neurons.
Changes in neuropeptide Y-like immunoreactivity (NPYir) in the rat L4 and L5 spinal cord and dorsal root ganglia (DRG) were examined after different sciatic nerve injuries (transection, loose ligation, and crush) and a localized, painful inflammation of the hind paw. Inflammation had no effect on NPYir. All the nerve injuries produced comparable increases in NPYir in ipsilateral laminae III-V axons and varicosities, and induction of NPYir in many DRG cells. Most NPYir DRG cells were medium to large (mean diameters: 40-45 microns); less than 2% of the cells had diameters of 25 microns or less. We conclude that the nerve injury-evoked increase in NPYir occurs mostly in the somata and intraspinal arbors of low-threshold mechanoreceptors; very few, if any, C-fiber afferents are involved. Nerve injury, rather than a painful condition, appears to be the stimulus for the induction of NPYir synthesis.
Wakisaka
S
S
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
Kajander
K C
KC
Bennett
G J
GJ
D000818:Animals; D005727:Ganglia, Spinal / Q000737:chemistry* / Q000166:cytology; D007249:Inflammation / Q000378:metabolism*; D008297:Male; D009475:Neurons, Afferent / Q000737:chemistry*; D009478:Neuropeptide Y / Q000032:analysis*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000293:injuries*; D013116:Spinal Cord / Q000737:chemistry
D009478:Neuropeptide Y