Baclofen in chronic neuropathic pain research

[Guest guest]

Research Abstract from Physiol Res. 2004;53(3):351-5.

GABA( receptor agonist baclofen has non-specific antinociceptive

effect in the model of peripheral neuropathy in the rat.

Franek M, Vaculin S, Rokyta R.

University, Third Faculty of Medicine, Dept. of Normal,

Pathological and Clinical Physiology, Ke Karlovu 4, 120 00 Prague 2,

Czech Republic.

Baclofen, which is a specific agonist of the metabotropic GABA(

receptor, is used in clinical practice for the treatment of spasticity

of skeletal muscles. It also exerts an analgesic effect, but this effect

is still not clear and especially controversial in neuropathic pain. In

this work, we studied the antinociceptive effects of baclofen in a model

of chronic peripheral neuropathic pain - loose ligation of the sciatic

nerve (chronic constriction injury, CCI). As controls we used

sham-operated animals. The changes of thermal pain threshold were

measured using the plantar test 15-25 days after the operation. The

obtained results suggest that baclofen increases pain threshold in both

groups. The antinociceptive effect of baclofen was dose-dependent and

the maximum response without motor deficits was observed at a dose of 15

mg/kg s.c. In the rats with CCI, significant differences between

affected (ipsilateral) and contralateral hind paw were present. This

difference was dose-dependent, the highest value (6.2+/-1.37 s) was

found at the dose of 20 mg/kg. Based on our results and previous

findings it could be summarized that baclofen has antinociceptive

action, which is attenuated in the model of chronic neuropathic pain

probably due to the degeneration of GABA interneurons after chronic

constriction injury.