, Volume 74, Issue 4, pp 321–324

Modifications of nutrient selection induced by naloxone in rats

  • Robin Marks-Kaufman
  • Robin B. Kanarek
Original Investigations

DOI: 10.1007/BF00432739

Cite this article as:
Marks-Kaufman, R. & Kanarek, R.B. Psychopharmacology (1981) 74: 321. doi:10.1007/BF00432739


Total caloric intake and dietary self-selection of the three macronutrients protein, fat, and carbohydrate were examined in male rats maintained on a 6-h feeding schedule following the administration of the opioid antagonist naloxone HCl (0.1, 1.0, and 10.0 mg/kg IP). Total caloric intake (calculated as the sum of caloric intakes from each of the macronutrients) was decreased for up to 2 h following naloxone administration. By the end of the 6-h feeding period, however, no differences in total caloric intakes were observed as a function of naloxone injections. Examination of intakes of the individual macronutrients revealed that naloxone differentially affected fat, carbohydrate, and protein consumption. Across the 6-h feeding period, animals consumed less calories from the fat ration following all three doses of naloxone than after saline injections. Carbohydrate intake was decreased for up to 2 h following naloxone injections, but returned to control values by the end of the 6-h feeding period. Protein intake, in contrast to fat and carbohydrate intakes, did not vary as a function of naloxone administration. Results of the present experiment are contrasted with patterns of dietary self-selection observed following morphine administration.

Key words

Dietary self-selectionProteinFatCarbohydrateNaloxoneCaloric intakeEndorphins

Copyright information

© Springer-Verlag 1981

Authors and Affiliations

  • Robin Marks-Kaufman
    • 1
  • Robin B. Kanarek
    • 1
  1. 1.Department of PsychologyTufts UniversityMedfordUSA