Effects of chronic delta 9-tetrahydrocannabinol administration on schedule-controlled behavior of pigeons: cross-tolerance to pentobarbital and barbital.
Pigeons responding under a variable-interval (VI) 75-s schedule of food presentation were used to study cross-tolerance from delta 9-tetrahydrocannabinol (delta 9-THC) to pentobarbital and barbital. After initial dose-effect functions for pentobarbital and barbital were determined, the birds received delta 9-THC injections for 6 weeks. This chronic administration regimen resulted in a greater than 100-fold tolerance to delta 9-THC. Redetermination of the pentobarbital and barbital dose-effect functions during the chronic delta 9-THC regimen revealed statistically significant shifts to the right for the pentobarbital (0.191 log unit) and barbital (0.078 log unit) dose-effect curves. All six birds showed tolerance to pentobarbital, while four of the six showed tolerance to barbital. Blood barbital levels before and after chronic delta 9-THC was more prolonged and of much greater magnitude than the cross-tolerance to pentobarbital or barbital. The results demonstrate that cross-tolerance can develop from delta 9-THC to a barbiturate that normally undergoes little metabolism.
D000818:Animals; D001462:Barbital / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D001463:Barbiturates / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects; D010856:Columbidae; D003216:Conditioning, Operant / Q000187:drug effects*; D013759:Dronabinol / Q000008:administration & dosage / Q000494:pharmacology*; D004361:Drug Tolerance; D008297:Male; D010424:Pentobarbital / Q000008:administration & dosage / Q000494:pharmacology*; D012055:Reinforcement Schedule
D001463:Barbiturates; D001462:Barbital; D013759:Dronabinol; D010424:Pentobarbital