Effects of peripheral nerve injuries and tissue inflammation on the levels of neuropeptide Y-like immunoreactivity in rat primary afferent neurons

• Published in: Brain research Vol. 598; no. 1-2; p. 349
• Main Authors: Wakisaka, S, Kajander, K C, Bennett, G J
• Format: Journal Article
• Language: English
• Published: Netherlands 11.12.1992
• Subjects: Animals; Ganglia, Spinal - chemistry; Ganglia, Spinal - cytology; Inflammation - metabolism; Male; Neurons, Afferent - chemistry; Neuropeptide Y - analysis; Pain - physiopathology; Rats; Rats, Sprague-Dawley; Sciatic Nerve - injuries; Spinal Cord - chemistry
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/0006-8993(92)90206-o

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.