Nicotinic acetylcholine receptors on capsaicin-sensitive nerves.
To study the density of nicotinic acetylcholine receptors on primary afferents and central nociceptive pathways, [3H](-)-nicotine binding was conducted in the cerebral cortex and spinal cord including dorsal roots and ganglia (DRG), of control rats and rats desensitized by neonatal capsaicin treatment. [3H](-)-nicotine binding in capsaicin-treated rats was reduced in cerebral cortex by 35% and spinal cord+DRG by 46% (p < 0.05). Functionally, both iontophoretically applied acetylcholine- and capsaicin-evoked flares (measured by laser Doppler flowmetry) were reduced in capsaicin-treated animals (p < 0.05); similarly, electrical stimulation-evoked flares were significantly lower in the same group, compared with controls (p < 0.05). These data provide direct evidence that many neuronal nicotinic acetylcholine receptors are associated with capsaicin-sensitive peptidergic neurones, including primary afferents, DRG and central nociceptive pathways.
Roberts
R G
RG
Department of Physiology, Monash University, Clayton, Victoria, Australia.
Stevenson
J E
JE
Westerman
R A
RA
Pennefather
J
J
D000344:Afferent Pathways / Q000187:drug effects; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects*; D004558:Electric Stimulation; D005260:Female; D008297:Male; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000032:analysis*; D013116:Spinal Cord / Q000187:drug effects*
D011978:Receptors, Nicotinic; D002211:Capsaicin