Food consumption inhibits pain-related behaviors.
The function of the endogenous analgesia system under natural circumstances has been little explored. Our recent work shows that animals are significantly less responsive to noxious stimulation during slow wave sleep, micturition, and while eating than during quiet wake. The analgesia associated with eating is dependent on activity in the medullary raphe magnus, the final common brain stem region in endogenous analgesia pathways. Eating analgesia does not depend on energy-depletion due to food deprivation. Further, analgesia accompanies chow-eating even though chow has no sucrose, demonstrating that sucrose is not a necessary component of analgesia-evoking ingestates. Since raphe magnus modulates processing of innocuous as well as nociceptive information, the sensory suppression accompanying eating is likely a more general depression of the response to external stimulation. Such a phenomenon would serve animals well under natural conditions where energy-dense food is scarce but has counterproductive effects, possibly contributing to obesity, in modern human society where energy-dense food is readily available.
Mason
Peggy
P
Department of Neurobiology, University of Chicago, Chicago, Illinois 60637, USA. pmason@uchicago.edu
Foo
H
H
D001933:Brain Stem / Q000503:physiopathology; D005247:Feeding Behavior; D006801:Humans; D010146:Pain / Q000503:physiopathology*