Involvement of GABA A receptor-associated chloride channels in the peripheral antinociceptive effect induced by GABA A receptor agonist muscimol.
The effect of chloride and potassium channel blockers on the antinociception induced by GABA(A) 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 GABA(A) receptor blocker, picrotoxin (0.4, 0.6, 0.8, 2 microg/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 GABA(A) receptor-associated chloride channels.
Reis
Glaucia
G
Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Av. Antônio Carlos 6627, 31270-100 Belo Horizonte, MG, Brazil.
Pacheco
Daniela
D
Francischi
Janetti
J
Castro
Maria
M
Perez
Andréa
A
Duarte
Igor
I
D000704:Analysis of Variance; D000818:Animals; D001640:Bicuculline / Q000008:administration & dosage / Q000494:pharmacology; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism; D015232:Dinoprostone; D004305:Dose-Response Relationship, Drug; D018755:GABA Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D018756:GABA Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D007279:Injections, Subcutaneous; D008297:Male; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology*; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy*; D010147:Pain Measurement; D010852:Picrotoxin / Q000008:administration & dosage / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D011312:Pressure; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects* / Q000378:metabolism
D001640:Bicuculline; D018118:Chloride Channels; D015232:Dinoprostone; D018755:GABA Agonists; D018756:GABA Antagonists; D009118:Muscimol; D010852:Picrotoxin; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D011963:Receptors, GABA-A