Delta-9-tetrahydrocannabinol induced response suppression in pigeons

Abstract

Response suppression following acute injections of Delta-9-tetrahydrocannabinol (9-THC) was compared between groups of White King or Silver King pigeons. Daily keypeck training continued until subjects’ responses were stable for 3 days. The day following criterion performance, each subject was injected with.250 mg/kg 9-THC,.125 mg/kg 9-THC, or the drug vehicle alone. Responses emitted during the ensuing session were cast into a ratio with the preceding criterion baseline to provide a proportion of response suppression attributable to 9-THC. Daily training continued after testing through a 12-day “washout” period, after which subjects were reeligible to attain criterion performance and be retested. All subjects were tested in each condition, with random assignment of injection sequences to subjects. Analysis of the results indicate that higher doses of 9-THC increased response suppression among both groups. This effect was more pronounced among Silver King pigeons, who as a group, differed significantly from the White Kings.