EEG and behavioral effects of delta9-tetrahydrocannabinol in combination with stimulant drugs in rabbits.

In rabbits, delta9-tetrahydrocannabinol (THC) at 0.5 mg/kg i.v., was challenged with i.v. methamphetamine (0.1 mg/kg), cocaine (1 mg/kg), apomorphine (1 mg/kg), or caffeine (12.5 mg/kg), and observations were made on quantified EEG and behavior. Cortical and hippocampal alterations produced by THC were antagonized by methamphetamine, cocaine, and caffeine and only briefly by apomorphine. Postural and activity behaviors were reversed by methamphetamine and caffeine but only briefly by cocaine and apomorphine. Additionally, stereotypy resulted from the combination of THC with methamphetamine, cocaine, or apomorphine. These data indicate that the effects of THC were antagonized by stimulant drugs of which caffeine was the most effective. However, novel toxicity also resulted from the interaction of THC with catecholaminergic drugs.