Effect of ketamine on spinal cord nociceptive transmission in normal and monoarthritic rats.
The effects of systemically and intrathecally administered ketamine on spinal wind-up of normal and monoarthritic rats were studied by using C-fiber reflex responses evoked by repetitive (0.6 Hz) electric stimulation. Both systemic and intrathecal ketamine induced dose-dependent depression of wind-up activity in normal rats, as revealed by the dose-related inhibitory effects of the drug. At the same intraperitoneal doses, ketamine produced a greater inhibitory effect on wind-up activity of monoarthritic rats, compared to normal animals. The intrathecal administration of ketamine also produced wind-up inhibition, the efficacy being higher in the monoarthritic rats. Results indicate that ketamine depresses spinal wind-up, specially in rats submitted to chronic pain, probably due to its antagonistic properties on dorsal horn NMDA receptors, which play a crucial role in the maintenance of chronic pain.
Laurido
C
C
Department of Biological Sciences, Faculty of Chemistry and Biology, University of Santiago of Chile.
Pelissier
T
T
Pérez
H
H
Flores
F
F
Hernández
A
A
D000818:Animals; D001168:Arthritis / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D007278:Injections, Spinal; D007649:Ketamine / Q000494:pharmacology*; D009412:Nerve Fibers / Q000502:physiology; D009619:Nociceptors / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012018:Reflex / Q000187:drug effects; D013116:Spinal Cord / Q000503:physiopathology*; D009435:Synaptic Transmission / Q000187:drug effects*
D018691:Excitatory Amino Acid Antagonists; D007649:Ketamine