Ghrelin-immunopositive hypothalamic neurons tie the circadian clock and visual system to the lateral hypothalamic arousal center

Tamas L. Horvath*, Alfonso Abizaid, Marcelo O. Dietrich, Ying Li, Joseph S. Takahashi, Joseph Bass

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Ghrelin, a circulating gut-hormone, has emerged as an important regulator of growth hormone release and appetite. Ghrelin-immunopositive neurons have also been identified in the hypothalamus with a unique anatomical distribution. Here, we report that ghrelin-labeled neurons receive direct synaptic input from the suprachiasmatic nucleus, the central circadian timekeeper of the brain, and lateral geniculate nucleus, a visual center, and project synaptically to the lateral hypothalamic orexin/hypocretin system, a region of the brain critical for arousal. Hypothalamic ghrelin mRNA oscillates in a circadian pattern peaking in the dark phase prior to the switch from arousal to sleep. Ghrelin inhibits the electrophysiological activity of identified orexin/hypocretin neurons in hypothalamic slices. These observations indicate that the hypothalamic neurons identified by ghrelin immunolabeling may be a key mediator of circadian and visual cues for the hypothalamic arousal system.

Original languageEnglish (US)
Pages (from-to)79-85
Number of pages7
JournalMolecular Metabolism
Volume1
Issue number1-2
DOIs
StatePublished - Dec 1 2012

Keywords

  • Arousal
  • Circadian rhythm
  • Ghrelin
  • Hypothalamus
  • Lateral hypothalamus

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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