A conus peptide blocks nicotinic receptors of unmyelinated axons in human nerves

• Published in: Neuroreport Vol. 16; no. 5; p. 479
• Main Authors: Lang, Philip M, Burgstahler, Ralf, Haberberger, Rainer V, Sippel, Wolfgang, Grafe, Peter
• Format: Journal Article
• Language: English
• Published: England 04.04.2005
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Aged; Aged, 80 and over; Calcium Channel Blockers - pharmacology; Conotoxins - pharmacology; Dose-Response Relationship, Drug; Drug Interactions; Female; Humans; Immunohistochemistry - methods; Male; Middle Aged; Nerve Fibers, Unmyelinated - drug effects; Nerve Fibers, Unmyelinated - metabolism; Neural Conduction - drug effects; Nicotine - pharmacology; Nicotinic Agonists; Peripheral Nervous System Diseases - physiopathology; Receptors, Nicotinic - classification; Receptors, Nicotinic - metabolism
• ISSN: 0959-4965
• DOI: 10.1097/00001756-200504040-00012

The novel alpha-conotoxin Vc1.1 is a potential analgesic for the treatment of painful neuropathic conditions. In the present study, the effects of Vc1.1 were tested on the nicotine-induced increase in excitability of unmyelinated C-fiber axons in isolated segments of peripheral human nerves. Vc1.1 in concentrations above 0.1 microM antagonized the increase in axonal excitability produced by nicotine; the maximal inhibition was observed with 10 microM. We also demonstrate immunoreactivity for alpha 3 and alpha 5 subunits of neuronal nicotinic receptors on unmyelinated peripheral human axons. Blockade of nicotinic receptors on unmyelinated peripheral nerve fibers may be helpful in painful neuropathies affecting unmyelinated sympathetic and/or sensory axons.