Medullary N-type and P/Q-type calcium channels contribute to neuropathy-induced allodynia

Neuroreport. 2005 Apr 25;16(6):563-6. doi: 10.1097/00001756-200504250-00009.

Abstract

The present study was designed to determine the contribution of N-type, P/Q-type and L-type calcium channels in the rostral ventromedial medulla to tactile allodynia following peripheral nerve injury. L5/L6 spinal nerve ligation in rats produced tactile allodynia, which was dose-dependently inhibited by intrarostral ventromedial medulla microinjection of the N-type calcium channel antagonist omega-conotoxin MVIIA. Similarly, intrarostral ventromedial medulla microinjection of the P/Q-type calcium channel antagonist omega-agatoxin IVA inhibited spinal nerve ligation-induced tactile allodynia, whereas intrarostral ventromedial medulla microinjection of the L-type calcium channel antagonist nimodipine had no effect. These results demonstrate that N-type and P/Q-type calcium channels in the rostral ventromedial medulla contribute to tactile allodynia following peripheral neuropathy, likely via neurotransmitter-mediated activation of descending facilitatory systems from the rostral ventromedial medulla.

MeSH terms

  • Animals
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels, N-Type / physiology*
  • Hyperalgesia / physiopathology
  • Ligation
  • Male
  • Medulla Oblongata / drug effects
  • Medulla Oblongata / physiology*
  • Microinjections
  • Neuralgia / physiopathology*
  • Rats
  • Rats, Sprague-Dawley
  • Spinal Nerves / physiology
  • Touch
  • omega-Agatoxin IVA / pharmacology
  • omega-Conotoxins / pharmacology

Substances

  • Calcium Channel Blockers
  • Calcium Channels, N-Type
  • omega-Agatoxin IVA
  • omega-Conotoxins
  • voltage-dependent calcium channel (P-Q type)
  • ziconotide