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Morphine enhances hedonic taste palatability in rats
T G Doyle1, K C Berridge, B A Gosnell
1Department of Psychology, University of Michigan, Ann Arbor 48109.
Pharmacology, Biochemistry, and Behavior
|November 1, 1993
Summary
Morphine, an opiate, increases food intake in rats by enhancing the pleasure derived from food
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Pharmacology
Background:
- Opiates are known to affect feeding behavior, but the precise mechanisms are not fully understood.
- It is hypothesized that opiates may stimulate feeding by increasing the hedonic (pleasurable) aspects of taste.
Purpose of the Study:
- To investigate whether morphine enhances feeding by increasing taste pleasure.
- To examine the effects of morphine on hedonic and aversive reactions to taste in rats.
Main Methods:
- Rats (n=12) received subcutaneous injections of morphine (4 mg/kg) or saline.
- Food intake was measured over a 2-hour test period.
- Hedonic and aversive taste reactions were assessed using slow-motion video analysis of responses to sucrose-quinine infusions.
Main Results:
- Morphine administration significantly increased food intake compared to saline.
- Rats treated with morphine exhibited significantly increased positive hedonic responses to taste.
- Aversive taste reactions remained unchanged by morphine treatment.
Conclusions:
- The findings support the hypothesis that morphine enhances feeding by increasing the palatability of food.
- Morphine's effect on feeding appears to be mediated, at least in part, by enhancing hedonic taste responses.