title: Orexin in the chicken hypothalamus: immunocytochemical localisation and comparison of mRNA concentrations during the day and night, and after chronic food restriction.
abstract: In mammals Orexin-A and -B are neuropeptides involved in the hypothalamic regulation of diverse physiological functions including food intake and the sleep-wake cycle. This generalisation was investigated in meat-(broiler) and layer-type juvenile domestic chickens by immunocytochemical localisation of orexin A/B in the hypothalamus, and by measurements of hypothalamic hypocretin mRNA which encodes for orexin A/B after chronic food restriction, and during the sleep-wake cycle. Orexin immunoreactive fibres were observed throughout the hypothalamus with cell bodies in and around the paraventricular nucleus. No differences were observed in the pattern of immunoreactivity using anti- human orexin-A, or -B antisera. The amount of hypothalamic hypocretin mRNA in food -restricted broilers was higher than in broilers fed ad libitum, but the same as in layer- type hens fed ad libitum. Hypothalamic hypocretin mRNA was increased (P<0.01) in 12-week-old broilers fed 25% of their ad libitum intake between 6-12 weeks of age. No difference in hypothalamic hypocretin mRNA was seen in 12-week-old layer- type hens when they were awake (1-2h after lights on) or sleeping (1-2h after lights off). It is concluded that in the chicken, we could not find evidence that hypothalamic orexin plays a role in the sleep-wake cycle and it may be involved in aspects of energy balance.
authors.affiliation: Department of Structures, Functions and Biological Technologies, University of Naples FedericoII, via Delpino1, I-80137 Naples, Italy.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Miranda
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Esposito
authors.forename: Paolo
authors.initials: P
authors.lastname: de Girolamo
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Sharp
authors.forename: Peter W
authors.initials: PW
authors.lastname: Wilson
authors.forename: Ian C
authors.initials: IC
authors.lastname: Dunn
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002645:Chickens; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D007031:Hypothalamus / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D008027:Light; D008297:Male; D009479:Neuropeptides / Q000235:genetics* / Q000378:metabolism*; D000068797:Orexins; D012333:RNA, Messenger / Q000378:metabolism*; D012890:Sleep / Q000502:physiology; D014851:Wakefulness / Q000502:physiology
chemical_list: C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D012333:RNA, Messenger