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Free keywords:
endocannabinoid, running, exercise, anxiety, anandamide
Abstract:
Exercise is rewarding, and long-distance runners have described a
runner's high as a sudden pleasant feeling of euphoria, anxiolysis,
sedation, and analgesia. A popular belief has been that endogenous
endorphins mediate these beneficial effects. However, running exercise
increases blood levels of both beta-endorphin (an opioid) and anandamide
(an endocannabinoid). Using a combination of pharmacologic, molecular
genetic, and behavioral studies in mice, we demonstrate that cannabinoid
receptors mediate acute anxiolysis and analgesia after running. We show
that anxiolysis depends on intact cannabinoid receptor 1 (CB1) receptors
on forebrain GABAergic neurons and pain reduction on activation of
peripheral CB1 and CB2 receptors. We thus demonstrate that the
endocannabinoid system is crucial for two main aspects of a runner's
high. Sedation, in contrast, was not influenced by cannabinoid or opioid
receptor blockage, and euphoria cannot be studied in mouse models.
