Pharmacological specificity of delta 9-tetrahydrocannabinol discrimination in rats.
R L Barrett, J L Wiley, R L Balster, B R Martin
Psychopharmacology April 1995 DOI: 10.1007/bf02245942 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Preclinical drug discrimination study Peer reviewed |
|---|---|
| Population | Rats trained to discriminate THC from vehicle |
| Interventions | delta 9-tetrahydrocannabinol (THC) l-phenylisopropyl adenosine dizocilpine dextromethorphan clozapine buspirone MDL 72222 muscimol midazolam chlordiazepoxide (+)-MDMA diazepam |
| Dose | THC 3.0 mg/kg; (+)-MDMA 2.5 mg/kg; diazepam 3.0 mg/kg |
| Topics | Cannabis |
| Key points | THC produced full dose-dependent substitution in rats trained to discriminate a 3.0 mg/kg THC dose from vehicle, while most non-cannabinoid compounds produced below-chance (under 50%) responding on the THC-appropriate lever. Only (+)-MDMA (2.5 mg/kg, 50%) and diazepam (3.0 mg/kg, 67%) reached or exceeded chance levels. The authors conclude that THC's discriminative stimulus effects show pharmacological specificity. |
Abstract
While many previous studies have shown that a variety of cannabinoids substitute and cross-substitute for delta 9-tetrahydrocannabinol (THC) in drug discrimination procedures, few have systematically examined potential THC-like effects of non-cannabinoid compounds. The purpose of the present study was to delineate further the pharmacological specificity of THC discrimination. Rats were trained to discriminate THC (3.0 mg/kg) from vehicle. Following determination of a dose-effect curve with THC, substitution tests with selected compounds from a variety of pharmacological classes, including l-phenylisopropyl adenosine, dizocilpine, dextromethorphan, clozapine, buspirone, MDL 72222, muscimol, midazolam and chlordiazepoxide, were performed. Whereas THC produced full dose-dependent substitution, substitution tests with non-cannabinoid drugs resulted in less than chance (50%) levels of responding on the THC-appropriate lever, with the exception of (+)-MDMA (2.5 mg/kg, 50%) and diazepam (3.0 mg/kg, 67%). These results are consistent with those of previous studies and suggest that the discriminative stimulus effects of THC exhibit pharmacological specificity.