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Psychopharmacology (Berl). 2011 Aug;216(3):355-65. doi: 10.1007/s00213-011-2226-3. Epub 2011 Mar 3.

Central mediation and differential blockade by cannabinergics of the discriminative stimulus effects of the cannabinoid CB1 receptor antagonist rimonabant in rats.

Author information

  • 1Center for Drug Discovery and Department of Pharmaceutical Sciences, Northeastern University, 360 Huntington Ave., Boston, MA 02115, USA. t.jarbe@neu.edu

Abstract

RATIONALE:

Discovery of an endocannabinoid signaling system launched the development of the blocker rimonabant, a cannabinoid CB1 receptor (CB(1)R) antagonist/inverse agonist. Due to untoward effects, this medication was withdrawn and efforts have been directed towards discovering chemicals with more benign profiles.

OBJECTIVE:

This study aims to comparatively evaluate new ligands using a rimonabant discriminated drinking aversion procedure.

METHODS:

Rats discriminated between rimonabant (5.6 mg/kg) and vehicle. The 30 min saccharin (0.1%) drinking after rimonabant pretreatment was followed by injection of lithium chloride (120 mg/kg) in the experimental animals. After vehicle pretreatment, experimental animals were given i.p. NaCl (10 ml/kg). Postdrinking treatment for controls was NaCl, irrespective of pretreatment condition (rimonabant or vehicle).

RESULTS:

The centrally acting neutral CB(1)R antagonist AM4113, but not the limited brain penetrating CB(1)R neutral antagonist AM6545, substituted for rimonabant. The CB(1)R agonists THC (1-10 mg/kg), AM1346 (1-10 mg/kg) did not substitute. The rimonabant-induced conditioned suppression of saccharin drinking was attenuated when CB(1)R agonists AM5983 (0.01-1 mg/kg) and THC (10 mg/kg), but not the CB(1)R agonist AM1346 (0.1-18 mg/kg), were combined with rimonabant (5.6 mg/kg). By varying the injection-to-test interval, we gauged the relative duration of the cueing effects of rimonabant, and the in vivo functional half-life was estimated to be approximately 1.5 h.

CONCLUSION:

A neutral CB(1)R antagonist (AM4113) produced cueing effects similar to those of rimonabant and generalization likely was centrally mediated. The functional cueing effects of rimonabant are relatively short-acting, pharmacologically selective, and differentially blocked by cannabinergics.

PMID:
21369753
[PubMed - indexed for MEDLINE]
PMCID:
PMC3727221
Free PMC Article

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