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

Neuroreport. 2005 Apr 4;16(5):479-83. 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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*


  • Calcium Channel Blockers
  • Conotoxins
  • Nicotinic Agonists
  • Receptors, Nicotinic
  • Nicotine