The effect of baclofen on spontaneous and evoked behavioural expression of experimental neuropathic chronic pain.
Baclofen (beta-p-chlorophenyl-GABA) has been used in humans to treat spasticity, as well as trigeminal neuralgia. Since GABA (gamma-aminobutyric acid) has been implicated in inhibitory and analgesic effects in the nervous system, it was of interest to study the effect of baclofen in experimental neuropathic pain. With this purpose, experiments were carried out in 17 neuropathic rats with constrictive sciatic injury, as described by Bennet and Xie (1988), taking as pain parameters scratching behaviour and the latency to the thermal nociceptive stimulus. The results showed that baclofen induces, in a dose-dependent manner, significant decrease (p < 0.05) of scratching behaviour and significant increase (p < 0.05) of the latency to the nociceptive thermal stimulus. The absence of antagonism of naloxone suggested a non-participation of an opioid-mediated mechanism in this analgesic effect of baclofen on experimental neuropathic pain.
Santos
T de J
Tde J
Department of Physiology and Pharmacology, Federal University of Ceará (UFC), Brazil.
de Castro-Costa
C M
CM
Giffoni
S D
SD
Santos
F J
FJ
Ramos
R S
RS
Gifoni
M A
MA
D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects*; D002908:Chronic Disease; D018755:GABA Agonists / Q000494:pharmacology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000627:therapeutic use; D010146:Pain / Q000503:physiopathology*; D010523:Peripheral Nervous System Diseases / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000503:physiopathology
D018755:GABA Agonists; D009292:Narcotic Antagonists; D009270:Naloxone; D001418:Baclofen