Sustained ingestion of delta 9-tetrahydrocannabinol and the operant behavior of stump-tailed macaques.
Three stump-tailed macaques were trained to press a lever for liquid reinforcement on a tandem schedule which required the animal to delay responding for at least 30 sec after each reinforcer. If the animal responded during that interval, a clock was reset thus re-establishing the delay requirement. If he delayed responding appropriately, the monkey was shifted to a fixed-interval schedule of 135 sec duration. The FI component was terminated with a drop of flavored liquid at which point the delay requirement began anew. Following a stable baseline performance, two monkeys received 2 mg/kg of THC orally every third day for 90 days with the placebo administered on intervening days. The third animal received the placebo throughout testing. Each monkey's performance was described in terms of response rate and response patterning between reinforcers. Despite the sustained ingestion of THC neither animal showed appreciable change in test behavior attributable to tolerance to the drug. Although the drug continued to have a powerful effect throughout testing on the days it was administered, there was no evidence of any consistent or cumulative drug effect on placebo-day performance.
D000818:Animals; D002188:Cannabis / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D013759:Dronabinol / Q000494:pharmacology*; D005260:Female; D000882:Haplorhini; D008297:Male; D010919:Placebos; D012055:Reinforcement Schedule; D013997:Time Factors
D010919:Placebos; D013759:Dronabinol