The effect of Delta9-tetrahydrocannabinol (THC) and CB1 antagonists on sucrose and quinine palatability: Direct measurement with the taste reactivity test

Anecdotal reports suggest that cannabinoid agonists enhance palatability and that antagonists reduce palatability; however there has been little direct experimental evidence for these claims. The taste reactivity (TR) test is a direct measure of palatability in rats (Grill & Norgren, 1978). In Experiments 1 and 4, the taste reactivity (TR) test was used to evaluate the potential of delta-9-tetrahydrocannabinol (THC) to modify both sucrose and quinine palatability. The TR test revealed that THC (0.5 mg/kg) increases the palatability of sucrose solutions at 120 min post-injection, regardless of the sucrose concentration. THC (0.5 mg/kg) also decreased the aversiveness of the quinine solution regardless of the post-injection interval (30 min, 60 min or 120 min). In Experiment 2, the CB 1 antagonist, SR141716 (2.5 mg/kg), reversed THC-induced enhancement of palatability, suggesting that enhancement of palatability is mediated by action at the CB 1 receptor. In Experiment 3, the CB 1 antagonist AM251 (1 mg/kg), was shown to suppress sucrose palatability but did not effect quinine palatability. The results of these experiments suggest that the modification of food intake by cannabinoid agonists and antagonists may be mediated by modification of palatability