Cross self-administration of delta 9-tetrahydrocannabinol and D-amphetamine in rats.

1. Schedule-induced intravenous self-injection of delta 9-tetrahydrocannabinol (delta 9-THC) and d-amphetamine was investigated in the same animals. 2. Rats self-injected significantly more amphetamine than delta 9-THC. However, the results suggested that delta 9-THC did not play a predisposing role to the increased amphetamine intake. When delta 9-THC was reinstated after amphetamine response rates were drastically reduced. 3. It is concluded that the reinforcing effects of delta 9-THC may be unrelated to its stimulant effects. The small number of responses for delta 9-THC is in agreement with reports of the poor reinforcing capability of cannabis compounds in rats.