Premium
The anti‐nausea effects of CB 1 agonists are mediated by an action at the visceral insular cortex
Author(s) -
Limebeer CL,
Rock EM,
Mechoulam R,
Parker LA
Publication year - 2012
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.2012.02066.x
Subject(s) - inverse agonist , agonist , nausea , taste aversion , chemistry , antagonist , pharmacology , receptor , medicine , endocrinology , taste , biochemistry
BACKGROUND AND PURPOSE Conditioned gaping reactions reflect nausea‐induced behaviour in rats. Cannabinoid 1 receptor (CB 1 ) agonists interfere with the establishment of nausea‐induced conditioned gaping; however, it is not known if their effects are mediated by an action at peripheral or central CB 1 receptors. EXPERIMENTAL APPROACH We utilized the conditioned gaping model of nausea to evaluate the effect of peripheral and central administration of the peripherally restricted CB 1 agonist, CB13, on the establishment of LiCl‐induced gaping in rats. We further evaluated the ability of HU‐210 administered to the gustatory insular cortex (GIC) or visceral insular cortex (VIC) to interfere with LiCl‐induced conditioned gaping and determined if this effect was mediated by CB 1 receptors. KEY RESULTS Central, but not peripheral, CB13 suppressed LiCl‐induced conditioned gaping. Central administration of the potent CB 1 agonist, HU‐210, delivered to the VIC, but not the GIC, suppressed the establishment of LiCl‐induced gaping reactions, but not LiCl‐induced suppression of hedonic reactions or conditioned taste avoidance. This pattern of results suggests that HU‐210 delivered to the VIC prevented LiCl‐induced nausea, but not learning per se . The suppression of LiCl‐induced conditioned gaping by HU‐210 was mediated by CB 1 receptors because it was prevented by co‐administration of CB 1 antagonist/inverse agonist, AM‐251, into the VIC. A high dose of AM‐251 (20 µg) administered alone into the VIC did not produce conditioned gaping reactions. CONCLUSIONS AND IMPLICATIONS The nausea‐relieving effects of CB 1 agonists, but not the nausea‐inducing effects of CB 1 inverse agonists, are mediated, at least in part, by their action at the VIC in rats.