Document Detail

Onset of feeding at birth--perinatal development of the hypothalamic mechanisms that induce appetite and feeding in the newborn.
MedLine Citation:
PMID:  18395343     Owner:  NLM     Status:  MEDLINE    
Orexin-A and -B are hypothalamic peptides which, in the adult brain, are associated with arousal, increased vigilance, and the seeking and ingestion of food. Because the fetus is mostly asleep, and hunger is a physiological state unlikely to arise until birth, we hypothesized that orexigenic neurons in the lateral and dorso-medial hypothalamic areas (LHA, DMH) and their projections to the locus coeruleus (LC) would develop only near the time of birth. We therefore determined orexin expression in fetal sheep, where birth occurs over a tightly regulated interval of 146-148 days gestation. Immunohistochemistry was used to determine the presence and distribution of orexin-A positive fibres and cells at the level of the hypothalamus and LC in fetal (125-137 and 145+ days gestation age) and newborn sheep brains. Orexin was measured by radioimmunoassay in plasma samples taken from chronically catheterised fetal and newborn sheep, and in CSF taken from fetuses and lambs at postmortem. Orexin-A positive cells bodies were observed in the hypothalamus, and orexin-A fibres were found throughout all hypothalamic, thalamic, and brain stem regions of all the fetal and newborn brains examined. Orexin-A was present in plasma and CSF at similar concentrations in fetal and newborn sheep. The presence of orexin in hypothalamic neurons and CSF throughout late gestation suggests that orexinergic regulation of hunger, appetite and the sleep/wake cycle is inhibited, by mechanisms yet to be identified, until the time of parturition.
Hayley Dickinson; David W Walker; Margie Castillo-Melendez
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Neuroscience letters     Volume:  436     ISSN:  0304-3940     ISO Abbreviation:  Neurosci. Lett.     Publication Date:  2008 May 
Date Detail:
Created Date:  2008-04-14     Completed Date:  2008-07-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7600130     Medline TA:  Neurosci Lett     Country:  Ireland    
Other Details:
Languages:  eng     Pagination:  1-6     Citation Subset:  IM    
Monash Immunology & Stem Cell Laboratories, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.
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MeSH Terms
Animals, Newborn
Appetite / physiology*
Feeding Behavior / physiology*
Hypothalamus / embryology*,  growth & development,  metabolism
Intracellular Signaling Peptides and Proteins / analysis,  metabolism*
Locus Coeruleus / embryology,  growth & development,  metabolism
Neurons / metabolism
Neuropeptides / analysis,  metabolism*
Thalamus / embryology,  growth & development,  metabolism
Reg. No./Substance:
0/Intracellular Signaling Peptides and Proteins; 0/Neuropeptides; 0/orexins

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