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

TitleGhrelin-immunopositive hypothalamic neurons tie the circadian clock and visual system to the lateral hypothalamic arousal center.
Publication TypeJournal Article
Year of Publication2012
AuthorsHorvath TL, Abizaid A, Dietrich MO, Li Y, Takahashi JS, Bass J
JournalMolecular metabolism
Volume1
Issue1-2
Pagination79-85
Date Published2012
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.

DOI10.1016/j.redox.2012.11.004
Alternate JournalMol Metab