Tolerance to delta9-tetrahydrocannabinol in adapted and nonadapted rabbits

Two groups of New Zealand white rabbits, one which had been adapted to the testing chamber and one which had not been adapted to the testing chamber, were given delta9-tetrahydrocannabinol (delta9-THC; 0.5 mg/kg, IV) daily for 12 days. During vehicle control and on the first and last day of delta9-THC administration, electroencephalograms (EEG's) were recorded from the motor cortex and hippocampus, while standing, sprawling and behavioral activity were recorded concurrently. The results showed that tolerance to the behavioral and EEG effects of delta9-THC occurs in rabbits and that acute and chronic effects produced by delta9-THC are influenced by environmental factors.