PT - JOURNAL ARTICLE AU - R B Carter AU - J D Leander TI - Comparison of the effects of naloxone and picrotoxin on schedule-controlled responding in the pigeon: possible GABA-antagonistic effects of naloxone. DP - 1984 Jul 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 40--46 VI - 230 IP - 1 4099 - http://jpet.aspetjournals.org/content/230/1/40.short 4100 - http://jpet.aspetjournals.org/content/230/1/40.full SO - J Pharmacol Exp Ther1984 Jul 01; 230 AB - The effects of naloxone and picrotoxin were determined alone and in conjunction with pentobarbital, diazepam or clonazepam, in pigeons responding under a multiple fixed-ratio 30-response, fixed-interval 5-min schedule of food presentation. Naloxone (10.0-80.0 mg/kg i.m.) and picrotoxin (0.1-0.56 mg/kg i.m.) alone produced only dose-related decreases in responding in both fixed-ratio and fixed-interval components. Pentobarbital (3.0 and 10.0 mg/kg i.m.) administered in combination with naloxone and picrotoxin shifted dose-response curves for both naloxone and picrotoxin to the right. In contrast, both diazepam (1.0-10.0 mg/kg p.o.) and clonazepam (0.3-3.0 mg/kg p.o.) attenuated the rate-decreasing effects of 0.56 mg/kg of picrotoxin, but not those of 80.0 mg/kg of naloxone. Dose-effect curves for naloxone and picrotoxin were then determined during daily administration of 10.0 mg/kg of diazepam. Dose-response curves for both naloxone and picrotoxin were shifted to the right under these conditions. These data support previous evidence that naloxone exerts gamma-aminobutyric acid-antagonistic effects in addition to its potent opioid-antagonistic effects.