Chronic treatment with Delta(9)-tetrahydrocannabinol enhances the locomotor response to amphetamine and heroin. Implications for vulnerability to drug addiction.
S Lamarque, K Taghzouti, H Simon
Neuropharmacology July 1, 2001 DOI: 10.1016/s0028-3908(01)00039-9 (opens in new tab) via PubMed
Summary
AI-generated from the abstractChronic 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.
Study at a glance
| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Rats |
| Interventions | Delta(9)-tetrahydrocannabinol amphetamine heroin |
| Dose | 0.6, 3 and 15 mg/kg THC; 1 mg/kg amphetamine; 1 mg/kg heroin |
| Duration | Chronic treatment followed by testing at 3 days (amphetamine) and 41 days (heroin) after last injection |
| Key finding | Chronic THC pre-treatment increased locomotor responses to amphetamine and heroin in high-responder rats, suggesting cross-sensitization that is time-dependent and limited to individuals vulnerable to drug taking. |
Abstract
Cannabis sativa preparations are some of the most widely used illicit recreational drugs. In addition to their direct addictive potential, cannabinoids may influence the sensitivity to other drugs. The aim of the present study was to determine if a cross-sensitization between Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and other drugs (amphetamine and heroin) could be demonstrated. We examined the effects of a chronic treatment with Delta(9)-THC (0.6, 3 and 15mg/kg, ip) on the locomotor response to amphetamine (1mg/kg, ip) and heroin (1mg/kg, ip). Chronic treatment with Delta(9)-THC resulted in tolerance to the initial hypothermic and anorexic effects. Pre-treatment with Delta(9)-THC increased the locomotor responses to amphetamine and heroin. This cross-sensitization was time-dependent as it was observed three days after the last injection of Delta(9)-THC for amphetamine, and a relatively long time after the end of chronic treatment (41 days) for heroin. Moreover, the enhanced response to amphetamine or heroin was noted in some individuals only: the high-responder rats (HR). These animals have previously been shown to be vulnerable to drug taking behaviors. It is hypothesised that repeated use of Cannabis derivates may facilitate progression to the consumption of other illicit drugs in vulnerable individuals.