Involvement of GABAA receptor-associated chloride channels in the peripheral antinociceptive effect induced by GABAA receptor agonist muscimol

The effect of chloride and potassium channel blockers on the antinociception induced by GABAA receptor agonist muscimol was investigated using the paw pressure test. Muscimol (1, 2, 4, 8 ng/paw) elicited a peripheral antinociceptive effect that was antagonized by bicuculline (10, 20, 40, 80 ng/paw), suggesting a specific effect. The muscimol effect was reverted by the chloride channel coupled GABAA receptor blocker, picrotoxin (0.4, 0.6, 0.8, 2 μg/paw). Potassium channel blockers did not modify the peripheral antinociception induced by muscimol. This study provides evidence that the peripheral antinociceptive effect of muscimol results from the activation of GABAA receptor-associated chloride channels.