title: The effect of age on prepro-orexin gene expression and contents of orexin A and B in the rat brain.
abstract: Orexin A and B (hypocretin 1 and 2) are hypothalamic peptides, which are synthesized in the lateral hypothalamus. Orexins participate in the regulation energy balance, food intake, vigilance and several endocrine and autonomic functions. The widespread projections of the orexin neurons suggest that they may have a role in coordination of different brain activities. The effects of ageing on the orexin system have not been studied previously. Prepro-orexin gene expression in the lateral hypothalamus, and the contents of orexin A and B peptides in the lateral hypothalamus and hypothalamus were measured in young, middle-aged and old (3, 12 and 24 months) rats. In the course of ageing, the expression of the prepro-orexin gene and the levels of orexin A and B decreased; the main decrease occurred by 12 months. Sleep deprivation for 6h increased slightly the expression of prepro-orexin gene in young rats. Deterioration of the orexin system may play a role in the phenomenon associated with aging, e.g. decreased consolidation of vigilance states, endocrine changes and dysfunctions of autonomic nervous system.
authors.affiliation: Institute of Biomedicine, University of Helsinki, P.O. Box 63, 000014 Helsinki, Finland. porkka@cc.helsinki.fi
authors.forename: Tarja
authors.initials: T
authors.lastname: Porkka-Heiskanen
authors.forename: Lauri
authors.initials: L
authors.lastname: Alanko
authors.forename: Anna
authors.initials: A
authors.lastname: Kalinchuk
authors.forename: Silja
authors.initials: S
authors.lastname: Heiskanen
authors.forename: Dag
authors.initials: D
authors.lastname: Stenberg
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002452:Cell Count / Q000379:methods; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D000068797:Orexins; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D012892:Sleep Deprivation / Q000378:metabolism; D014851:Wakefulness / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D011498:Protein Precursors