Evidence for separate neuronal mechanisms for the discriminative stimulus and catalepsy induced by delta 9-THC in the rat.
W R Prescott, L H Gold, B R Martin
Psychopharmacology 1992 DOI: 10.1007/bf02244975 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study Peer reviewed |
|---|---|
| Population | Rats |
| Interventions | delta 9-THC anticholinergic pretreatment naloxone |
| Topics | Cannabis |
| Key findings | Delta 9-THC produced discriminative stimulus effects at an ED50 of 0.8 mg/kg and catalepsy at 4.0 mg/kg, with similar time courses. Catalepsy was not attenuated by long-term low-dose exposure. Anticholinergic pretreatment eliminated catalepsy but not discriminative stimulus effects, indicating distinct mechanisms for these cannabinoid-induced behaviors. |
Abstract
The cataleptogenic effect of delta 9-THC was compared to its discriminative stimulus effects in rats. The ED50s for the discriminative stimulus and catalepsy were 0.8 and 4.0 mg/kg, respectively, while their time courses were very similar. The ED50 of delta 9-THC for catalepsy in experimentally naive rats was not different from that in rats trained with the drug discrimination procedure, indicating that the cataleptogenic effect was not appreciably attenuated by long-term exposure to low doses of delta 9-THC. Pharmacologically, the catalepsy produced by delta 9-THC more closely resembled that of haloperidol than of morphine, since anticholinergic pretreatment eliminated the delta 9-THC-induced catalepsy while pre-treatment with naloxone had no effect. Although the cataleptogenic effect of delta 9-THC could be pharmacologically manipulated by anticholinergic pre-treatment, its discriminative stimulus effects were not changed in the same animals. These results demonstrate that distinctive mechanisms of action exist for these cannabinoid-induced behaviors.