Identification and Functional Characterization of Brainstem Cannabinoid CB 2 Receptors

The presence and function of CB 2 receptors in central nervous system (CNS) neurons are controversial. We report the expression of CB 2 receptor messenger RNA and protein localization on brainstem neurons. These functional CB 2 receptors in the brainstem were activated by a CB 2 receptor agonist, 2-arachidonoylglycerol, and by elevated endogenous levels of endocannabinoids, which also act at CB 1 receptors. CB 2 receptors represent an alternative site of action of endocannabinoids that opens the possibility of nonpsychotropic therapeutic interventions using enhanced endocannabinoid levels in localized brain areas.