THC and Endocannabinoid-Boosting Drugs Reduced Brain Reward Signaling in Mice

Male mice underwent intracranial self-stimulation testing, operant responding for food, and locomotor activity measurements. THC, JZL184, PF-3845, and SA-57 were tested at multiple doses. Brain endocannabinoid levels were quantified. CB1 and CB2 antagonists were used to determine receptor involvement.

The finding that THC and 2-AG boosting reduce brain reward signaling, rather than enhance it, helps explain why THC's reinforcing effects have been difficult to detect in rodent models. It also clarifies that the two main endocannabinoids (anandamide and 2-AG) have different effects on reward circuits.

This research complicates the simple narrative that cannabinoids activate the reward system like other drugs of abuse. Instead, THC and endocannabinoid elevation appear to suppress reward-seeking behavior in this paradigm, which may help explain why cannabis has a lower addictive potential than some other substances.

ICSS is one model of reward but does not capture all aspects of drug reinforcement. Mice were tested acutely, and chronic effects may differ. The doses used may not reflect typical human cannabis exposure patterns. Rodent reward neurobiology does not perfectly map to human experience.