Δ9-tetrahydrocannabinol produced discrimination in pigeons

Abstract

In an operant situation pigeons learned to peck one response key 90 min after an injection of 0.25 mg/kg Δ 9-tetrahydrocannabinol ( Δ 9-THC) and another key when trained nondrugged. When tested with doses of Δ 9-THC lower than the training dose the birds discriminated 0.20 mg/kg of the drug from the nondrugged state but not 0.15 mg/kg or lower doses. The animals were able to discriminate the drug state from the nondrugged 180 min but not 360 min after the injection. At ashorter interval (45 min) both drug and nondrug responding appeared. Cannabinol and cannabidiol (4.0 – 8.0 mg/kg) did not elict any drug responses, nor did pentobarbital, ditran or amphetamine. Tests with LSD resulted in both drug and nondrug responding. When administering noncannabinoid drugs in combination with Δ 9-THC 0.15 mg/kg the birds responded at the key associated with the drug state, suggesting interactional effects.