Research article summary (published 12 Oct 2009):

Analgesia accompanying food consumption requires ingestion of hedonic foods.

Full Abstract

Animals eat rather than react to moderate pain. Here, we examined the behavioral, hedonic, and neural requirements for ingestion analgesia in ad libitum fed rats. Noxious heat-evoked withdrawals were similarly suppressed during self-initiated chocolate eating and ingestion of intraorally infused water, sucrose, or saccharin, demonstrating that ingestion analgesia does not require feeding motivation, self-initiated food procurement, sucrose, or calories. Rather, food hedonics is important because neither salt ingestion nor quinine rejection elicited analgesia. During quinine-induced nausea and lipopolysaccharide (LPS)-induced illness, conditions when chocolate eating was presumably less pleasurable, analgesia accompanying chocolate consumption was attenuated, yet analgesia during water ingestion was preserved in LPS-injected rats who showed enhanced palatability for water within this context. The dependence of ingestion analgesia on the positive hedonics of an ingestate was confirmed in rats with a conditioned taste aversion to sucrose: after paired exposure to sucrose and LPS, rats no longer showed analgesia during sucrose ingestion but continued to show analgesia during chocolate consumption. Eating pauses tended to occur less often and for shorter durations in the presence of ingestion analgesia than in its absence. Therefore, we propose that ingestion analgesia functions to defend eating from ending. Muscimol inactivation of the medullary raphe magnus blocked the analgesia normally observed during water ingestion, showing the involvement of brainstem endogenous pain inhibitory mechanisms in ingestion analgesia. Brainstem-mediated defense of the consumption of palatable foods may explain, at least in part, why overeating tasty foods is so irresistible even in the face of opposing cognitive and motivational forces.

Author information

Author/s: Foo, H (H); Mason, Peggy (P);

Affiliation: Department of Neurobiology and Committee on Neurobiology, University of Chicago, Chicago, Illinois 60637, USA.

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience (J Neurosci), published in United States. (Language: eng)

Reference: 2009-Oct; vol 29 (issue 41) : pp 13053-62

Dates: Created 2009/10/15; Completed 2009/10/30;

PMID: 19828818, status: MEDLINE (last retrieval date: 10/30/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Analgesia Analgesics, Non-Narcotic - administration & dosage; pharmacology Analysis of Variance Animals Avoidance Learning - drug effects; physiology Behavior, Animal - drug effects; physiology Cacao Conditioning, Classical - drug effects; physiology Conditioning, Operant - drug effects; physiology Eating - drug effects; physiology Electromyography - methods Feeding Behavior - drug effects; physiology

Feeding Behavior - drug effects; physiology Food Preferences - drug effects; physiology Hot Temperature - adverse effects Hypnotics and Sedatives - pharmacology Lipopolysaccharides - pharmacology Male Pentobarbital - pharmacology Quinine - administration & dosage Rats Rats, Sprague-Dawley Reaction Time - drug effects Sweetening Agents - administration & dosage; pharmacology

Associated Chemicals: Analgesics, Non-Narcotic (0) ; Hypnotics and Sedatives (0) ; Lipopolysaccharides (0) ; Sweetening Agents (0) ; Quinine (130-95-0) ; Pentobarbital (76-74-4)

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