Selective inhibitory effects of pregabalin on peripheral C but not A-delta fibers mediated nociception in intact and spinalized rats

Neuroscience. 2009 Dec 29;164(4):1845-53. doi: 10.1016/j.neuroscience.2009.09.047. Epub 2009 Sep 25.

Abstract

Effects of pregabalin (PGB, 20-80 mg/kg i.v. injection) on spinally-organized nociception were investigated in isoflurane-anesthetized intact and spinalized rats. Responses of single deep spinal dorsal horn (DH) (laminae IV-V) nociceptive-specific (NS) neurons receiving peripheral inputs from A-delta and C fibers to repetitive electrical stimulation (intensity: 3-5 mA; frequency: 1 Hz; pulse duration: 1 ms), mechanical/heat stimulation were recorded extracellularly during physiological condition and s.c. bee venom (BV) induced inflammation. PGB significantly inhibited C-fiber mediated spinal NS neurons' late responses including phenomena of wind-up (temporal summation) and after-discharge. However, the antinociceptive effects of PGB on nociception were not observed until 30 min after its administration. In contrast, no significant inhibitory effect of PGB on A-delta fiber mediated early responses was observed during the experiments. Compared with intact rats, the inhibitory effects of PGB upon nociception vanished in the spinalized animals. This suggests that PGB-induced selective antinociceptive effect on C-fiber mediated nociception is mainly central effects involving supraspinal centers via descending inhibitory controls. Furthermore, pre-treatment, but not post-treatment, with PGB (80 mg/kg) markedly inhibited s.c. BV elicited spontaneous neuronal responses, and noxious mechanical/heat stimuli evoked hyperactivities of spinal NS neurons, indicating that PGB has efficacy of pre-emptive analgesia on pathological pain associated with central sensitization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anticonvulsants / pharmacology*
  • Decerebrate State
  • Electric Stimulation
  • Male
  • Nerve Fibers, Myelinated / drug effects*
  • Nerve Fibers, Myelinated / physiology
  • Nerve Fibers, Unmyelinated / drug effects*
  • Nerve Fibers, Unmyelinated / physiology
  • Neurons / drug effects
  • Neurons / physiology
  • Pain / physiopathology*
  • Pregabalin
  • Rats
  • Rats, Wistar
  • Spinal Cord / physiopathology
  • gamma-Aminobutyric Acid / analogs & derivatives*
  • gamma-Aminobutyric Acid / pharmacology

Substances

  • Anticonvulsants
  • Pregabalin
  • gamma-Aminobutyric Acid