The effects of morphine on diet selection are dependent upon baseline diet preferences

Blake A. Gosnell, Dean D. Krahn, Mark J. Majchrzak

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


It has been reported that morphine causes a selective increase in the intake of dietary fat. Because we have noted considerable variability among rats in their preferences for carbohydrate and fat, we reasoned that the effect of morphine on diet selection may differ in fat-preferring vs. carbohydrate-preferring rats. Male Sprague-Dawley rats were given ad lib access to separate sources of carbohydrate, fat and protein (Experiment 1), or to a carbohydrate/protein and a fat/protein diet (Experiment 2). After daily baseline intakes of the diets were determined, all rats were tested for feeding responses to subcutaneous injections of morphine (0, 2 and 10 mg/kg). Significant positive correlations were found between baseline daily intake of a given diet and the effect of morphine on the intake of that diet. Generally, morphine increased carbohydrate intake in carbohydrate-preferring rats, and increased fat intake in fat-preferring rats. These results suggest that the effect of morphine is to increase intake of a preferred diet rather than to increase intake of a specific macronutrient.

Original languageEnglish (US)
Pages (from-to)207-212
Number of pages6
JournalPharmacology, Biochemistry and Behavior
Issue number2
StatePublished - Oct 1990
Externally publishedYes

Bibliographical note

Funding Information:
We thank Drs. Alien S. Levine and Dale R. Romsos for their advice on diet compositions. This research was supported by NIDA grant DA05471.


  • Carbohydrate
  • Diet selection
  • Fat
  • Feeding
  • Food intake
  • Macronutrient
  • Morphine
  • Opioids
  • Protein


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