Ghrelin induces feeding in the mesolimbic reward pathway between the ventral tegmental area and the nucleus accumbens

Amy M. Naleid, Martha K. Grace, David E. Cummings, Allen S Levine

Research output: Contribution to journalArticlepeer-review

296 Scopus citations

Abstract

Ghrelin, a powerful orexigenic peptide released from the gut, stimulates feeding when injected centrally and has thus far been implicated in regulation of metabolic, rather than hedonic, feeding behavior. Although ghrelin's effects are partially mediated at the hypothalamic arcuate nucleus, via activation of neurons that co-express neuropeptide Y and agouti-related protein (NPY/Agrp neurons), the ghrelin receptor is expressed also in other brain sites. One of these is the ventral tegmental area (VTA), a primary node of the mesolimbic reward pathway, which sends dopaminergic projections to the nucleus accumbens (Acb), among other sites. We injected saline or three doses of ghrelin (0, 0.003, 0.03, or 0.3 nmol) into the VTA or Acb of rats. We found a robust feeding response with VTA injection of ghrelin, and a more moderate response with Acb injection. Because opioids modulate feeding in the VTA and Acb, we hypothesized that ghrelin's effects in one site were dependent on opioid signaling in the opposite site. The general opioid antagonist, naltrexone (NTX), injected into the Acb did not affect feeding elicited by ghrelin injection into the VTA, and NTX in the VTA did not affect feeding elicited by ghrelin injected into the Acb. These results suggest interaction of a metabolic factor with the reward system in feeding behavior, indicating that hedonic responses can be modulated by homeostatic factors.

Original languageEnglish (US)
Pages (from-to)2274-2279
Number of pages6
JournalPeptides
Volume26
Issue number11
DOIs
StatePublished - Nov 1 2005

Keywords

  • Food intake
  • Ghrelin
  • Microinjection
  • Opioid
  • Rat
  • Reward

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