Abstract
The prototypic cannabinoid CB1 antagonist SR 141716A is one important pharmacologic tool for examining CB1 receptors that mediate the behavioral and physiologic effects of Δ9- tetrahydrocannabinol (Δ9-THC). This study examined the effects of SR141716A on the rate-decreasing, hypothermic and discriminative stimulus effects of Δ9-THC in rhesus monkeys. In monkeys (n=4) responding under a multiple fixed ratio (FR-10:FR-10) schedule of food presentation and stimulus-shock termination, the potency of i.m. Δ9-THC to decrease responding in the food component (ED 50=0.64 mg/kg) was threefold greater than its potency in the stimulus-shock termination component (ED50=2.14 mg/kg). In the same monkeys, hypothermia was induced by Δ9-THC at a dose (e.g. 0.32 mg/kg) that did not alter responding in either schedule component; the maximum decrease was 2.1°C at a dose of 3.2 mg/kg. A dose of 0.32 mg/kg of SR 141716A, significantly attenuated Δ9-THC-induced hypothermia without attenuating the rate-decreasing effects of Δ9-THC in either component of the multiple schedule. The largest dose of i.m. SR 141716A that was studied, 1.0 mg/kg, significantly decreased rectal temperature and responding in the food component but did not significantly decrease responding in the stimulus-shock termination component of the multiple schedule. In a separate group of monkeys (n=3) that discriminated i.v. Δ9-THC (0.1 mg/kg) while responding under an FR-5 schedule of stimulus-shock termination, SR 141716A (0.32 and 1 mg/kg) significantly increased the ED 50 of the Δ9-THC by 2.3- and 3.7-fold, respectively. Collectively, these results demonstrate that the behavioral effects of Δ9-THC are not equally attenuated by SR 141716A.
Original language | English (US) |
---|---|
Pages (from-to) | 363-372 |
Number of pages | 10 |
Journal | Behavioural pharmacology |
Volume | 16 |
Issue number | 5-6 |
DOIs | |
State | Published - Sep 2005 |
Keywords
- Antagonist
- Cannabinoid
- Hypothermia
- Rhesus monkey
- SR 141716A
- Schedule-controlled behavior
- Δ-THC
ASJC Scopus subject areas
- Pharmacology
- Psychiatry and Mental health