GABAA-antagonists and baclofen analgesia.
1. Intraperitoneal (i.p.) injection of different doses of baclofen (5, 7.5 and 10 mg/kg) induced analgesia in tail-flick test. The effect was dose-dependent. 2. The antinociception induced by baclofen (10 mg/kg, i.p.) was decreased in animals pretreated with bicuculline (1.5 mg/kg, i.p., 30 min), but not with naloxone (1.5 mg/kg, i.p., 30 min). 3. In picrotoxin (1 mg/kg, i.p., 15 min) pretreated mice, baclofen (5 mg/kg, i.p.) showed a significant analgesic effect. 4. Morphine (6 mg/kg, s.c.) induced analgesia which was antagonized by naloxone pretreatment (1.5 mg/kg, i.p.), while bicuculline or picrotoxin did not alter the morphine response. 5. These data suggest that a part of analgesic effect of baclofen may be mediated through GABAA receptor sites, and differs from that of morphine.
Zarrindast
M R
MR
Department of Pharmacology, Faculty of Medicine, University of Tehran, Iran.
Djavdan
M
M
D000698:Analgesia; D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D001640:Bicuculline / Q000494:pharmacology; D018756:GABA Antagonists; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D010852:Picrotoxin / Q000494:pharmacology; D013997:Time Factors
D001418:Baclofen; D001640:Bicuculline; D018756:GABA Antagonists; D009020:Morphine; D009270:Naloxone; D010852:Picrotoxin