Chronic treatment with Delta(9)-tetrahydrocannabinol enhances the locomotor response to amphetamine and heroin. Implications for vulnerability to drug addiction.
Neuropharmacology July 1, 2001 S Lamarque, K Taghzouti, H Simon
Chronic administration of Delta(9)-tetrahydrocannabinol (THC) in rats increased their locomotor response to subsequent amphetamine and heroin injections, demonstrating cross-sensitization. This effect was time-dependent: enhanced response to amphetamine appeared three days after the last THC dose, while the response to heroin emerged 41 days later. The sensitization occurred only in high-responder rats, a subpopulation previously identified as vulnerable to drug-taking behaviors. The authors hypothesize that repeated cannabis use may facilitate progression to other illicit drugs in vulnerable individuals.