Environment modulates naloxone's suppressive effect on feeding in diabetic and non-diabetic rats

A. S. Levine, J. E. Morley, J. Kneip, M. Grace, D. M. Brown

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19 Scopus citations


We evaluated the effect of environment on naloxone-induced suppression of feeding in streptozotocin rats and sham injected controls. Naloxone was administered to animals fasted for 24 hours and food intake was measured at 30, 60 and 120 minutes. Diabetic rats, in their home cages, were insensitive to naloxone's suppressive effect for the first 30 minutes and the 5 mg/kg dose suppressed feeding only at 120 minutes. In control rats, feeding was suppressed at 1 and 5 mg/kg naloxone during the first 30 minutes. In contrast, when animals were placed in novel plastic cages, control animals were insensitive to naloxone at all time points at doses as high as 5 mg/kg. In novel cages, diabetic rats responded to doses of 1 and 5 mg/kg during the first 30 minute period by lowering food intake. It should also be noted that basal food intake was suppressed (40-53%) when animals were placed in novel cages. These data suggest that stress of a novel environment alters the neuroregulatory system involved in inducing feeding. Lack of response of normal rats to naloxone's suppressive effect in a novel environment suggests that (1) a non-opioid feeding system operates under these conditions, or (2) opioid receptors are occupied as a result of the release of endogenous opioids due to stress. The opposite result observed in the diabetics indicates that glucose has a modulating effect on opioid effects.

Original languageEnglish (US)
Pages (from-to)391-393
Number of pages3
JournalPhysiology and Behavior
Issue number3
StatePublished - Mar 1985

Bibliographical note

Copyright 2017 Elsevier B.V., All rights reserved.


  • Diabetes
  • Environment
  • Naloxone
  • Opioid feeding


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