Activating CB2 Receptors While Blocking Dopamine D4 Reduced Binge Eating More Than Either Alone in Mice

In mice given 1-hour access to palatable food, a dopamine D4 receptor antagonist (L-745870) reduced binge-like intake. Adding a CB2 receptor agonist (HU308) to the D4 antagonist produced an even greater reduction. The CB2 antagonist (AM630) combined with the D4 antagonist did not enhance the effect, suggesting the additional benefit came specifically from CB2 activation.

34 adult male C57BL6/J mice housed individually with ad libitum standard diet. Binge eating was modeled by providing 1-hour access to palatable food across 12 baseline sessions. Mice were then randomly assigned to four treatment groups (vehicle, D4 antagonist alone, D4 antagonist + CB2 agonist, D4 antagonist + CB2 antagonist) for three additional sessions.

Binge eating disorder involves dysregulation of the brain's reward system. This study reveals a previously unknown interaction between the cannabinoid and dopamine systems in controlling binge-like behavior, suggesting that targeting both systems simultaneously could be more effective than targeting either alone.

The endocannabinoid system's role in appetite and reward is well established through CB1 receptors, but CB2's involvement in eating behavior is a newer finding. This study adds to growing evidence that CB2 receptors in dopamine neurons help modulate reward-driven behaviors beyond just drug seeking.

Animal study in male mice only; no female mice tested. Small sample size per group. Short treatment period (3 sessions). Palatable food binge model may not fully capture human binge eating disorder. Only intraperitoneal drug administration tested.