title: The orexinergic system in rainbow trout Oncorhynchus mykiss and its regulation by dietary lipids.
abstract: In this study, we report the distribution of orexin A (OXA), orexin B (OXB), and orexin receptor (OX2R) immunoreactive (ir) cells in the hypothalamus and gastrointestinal tract of Oncorhynchus mykiss fed diets with different dietary fatty acid compositions. Trout were fed five iso-energetic experimental diets containing fish oil, or one of four different vegetable oils (olive, sunflower, linseed, and palm oils) as the added dietary lipid source for 12 weeks. OXA, OXB, and OX2R immunoreactive neurons and nervous fibers were identified in the lateral and ventro-medial hypothalamus. OXA, OXB, and OX2R ir cells were found in the mucosa and glands of the stomach and in the mucosa of both the pyloric cecae and intestine. OX2R ir cells were localized in the mucosa layer of both the pyloric cecae and intestine. These immunohistochemical (IHC) results were confirmed via Western blotting. Antibodies against preproorexin (PPO) crossreacted with a band of ∼16 kDa in the hypothalamus, stomach, pyloric cecae, and intestine. Antibodies against OX2R crossreacted with a band of ∼38 kDa in the hypothalamus, pyloric cecae, and intestine. The presence and distribution of OXA, OXB, and OX2R ir cells in the hypothalamus and gastrointestinal tract did not appear to be affected by dietary oils. The presence of orexin system immunoreactive cells in the stomach, pyloric cecae, and intestine of rainbow trout, but not in the enteric nervous system, could suggest a possible role of these peptides as signaling of gastric emptying or endocrine modulation, implying a main local action played by orexins.
authors.affiliation: Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Varricchio
authors.affiliation: Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy.
authors.forename: Finizia
authors.initials: F
authors.lastname: Russo
authors.affiliation: Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Coccia
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Warrnambool, Victoria, Australia.
authors.forename: Giovanni Mario
authors.initials: GM
authors.lastname: Turchini
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Warrnambool, Victoria, Australia.
authors.forename: David Scott
authors.initials: DS
authors.lastname: Francis
authors.affiliation: Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy.|Institute of Nutrition (ISA), Avellino, 83100, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Paolucci
mesh_terms: D000818:Animals; D004041:Dietary Fats / Q000378:metabolism*; D029941:Fish Proteins / Q000378:metabolism*; D005753:Gastric Mucosa / Q000737:chemistry / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D007031:Hypothalamus / Q000737:chemistry / Q000378:metabolism; D007150:Immunohistochemistry; D017686:Oncorhynchus mykiss / Q000378:metabolism* / Q000502:physiology*; D000068797:Orexins / Q000378:metabolism*
chemical_list: D004041:Dietary Fats; D029941:Fish Proteins; D000068797:Orexins
keywords: gastrointestinal tract; hypothalamus; orexin A; orexin B; orexin receptor; prepro-orexin; rainbow trout