Increased expression of mu opioid receptors in animals susceptible to diet-induced obesity

Maria J. Barnes, Gregory Holmes, Stefany D. Primeaux, David A. York, George A. Bray

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Abstract

Stimulation of mu opioid receptors preferentially increases the intake of a high fat diet. In this paper we investigated whether there was a difference in the expression of mu opioid receptors between animals susceptible (Osborne-Mendel) or resistant (S5B/Pl) to obesity induced by eating a high fat diet. Immunohistochemical studies demonstrated that Osborne-Mendel rats eating a chow diet had an increased number of mu opioid receptors in the arcuate nucleus when compared to S5B/Pl rats. These immunohistochemical findings were supported by Real Time-PCR which demonstrated that the mRNA level of mu opioid receptors was also increased in the hypothalamus of Osborne-Mendel rats compared to S5B/Pl rats. Low doses of the mu opioid receptor agonist DAMGO [d-Ala2-N-Me-Phe4-Glycol5]-enkephalin administered to Osborne-Mendel rats caused a significant increase in the preference for a diet high in fat. The same doses of DAMGO switched the diet preference of S5B/Pl rats to high fat but did not significantly increase food intake. The combination of these findings suggests that the increased levels of hypothalamic mu opioid receptors in Osborne-Mendel rats may contribute to their preference for a diet high in fat and increase their susceptibility to becoming obese.

Original languageEnglish (US)
Pages (from-to)3292-3298
Number of pages7
JournalPeptides
Volume27
Issue number12
DOIs
Publication statusPublished - Dec 1 2006

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physiology
  • Endocrinology
  • Cellular and Molecular Neuroscience

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