Assessing the Role of the Growth Hormone Secretagogue Receptor in Motivational Learning and Food Intake

Alexander W. Johnson, Rebecca Canter, Michela Gallagher, Peter C. Holland

Research output: Contribution to journalArticlepeer-review

Abstract

The orexigenic neuropeptide ghrelin is an endogeneous ligand for the growth hormone secretagogue receptor (GHS-R). This orexigen is expressed in both the periphery and in the central system, including portions of mesolimbic dopaminergic circuitry that play a role in affective behaviors. Here we examined pharmacological antagonism of GHS-R in motivational incentive learning, as reflected in Pavlovian-to-instrumental transfer (PIT). Furthermore, it is currently unclear whether the previous effects of ghrelin on food intake are mediated by pre- and/or postingestive influences on ingestive behavior. Thus, the authors also conducted detailed analyses of the temporal dynamics of sucrose licking. Mice received low (50 nmol), moderate (100 nmol), and high (200 nmol) intraperitoneal injections of the GHS-R antagonist GHRP-6 [D-Lys3] prior to subsequent transfer and sucrose consumption tests. Low and moderate doses led to an augmentation of PIT, while high dose injections led to generalized performance deficits. In addition, moderate and high doses of the antagonist resulted in reductions in sucrose intake by reducing palatability of the sucrose. These results suggest dissociable functions of GHS-R in its influence over motivational learning and ingestive behavior.

Original languageEnglish (US)
Pages (from-to)1058-1065
Number of pages8
JournalBehavioral Neuroscience
Volume123
Issue number5
DOIs
StatePublished - Oct 2009

Keywords

  • Pavlovian to instrumental transfer
  • ghrelin
  • licking microstructure
  • mice
  • palatability

ASJC Scopus subject areas

  • Behavioral Neuroscience

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