title: Heat and oxidative stress alter the expression of orexin and its related receptors in avian liver cells.
abstract: Orexins (A and B) or hypocretins (1 and 2) are hypothalamic orexigenic neuropeptides that are involved in the regulation of several physiological processes in mammals. Recently, orexin has been shown to activate the hypothalamic-pituitary-adrenal (HPA) stress axis and emerging evidences identify it as a stress modulator in mammals. However, the regulation of orexin system by stress itself remains unclear. Here, we investigate the effects of heat, 4-Hydroxynonenal (4-HNE) and hydrogen peroxide (H2O2) stress on the hepatic expression of orexin (ORX) and its related receptors (ORXR1/2) in avian species. Using in vivo and in vitro models, we found that heat stress significantly down-regulated ORX and ORXR1/2 mRNA and protein abundances in quail liver and LMH cells. H2O2, however, decreased ORX protein and increased ORX mRNA levels in a dose dependent manner (P<0.05). The absence of correlation between orexin mRNA and protein levels suggests that H2O2 treatment modulates post-transcriptional mechanisms. 4-HNE had a biphasic effect on orexin system expression, with a significant up-regulation at low doses (10 and 20μM) and a significant down-regulation at a high dose (30μM). Taken together, our data indicated that hepatic orexin system could be a molecular signature in the heat and oxidative stress response.
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Greene
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Khaldi
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Ishola
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Walter
authors.initials: W
authors.lastname: Bottje
authors.affiliation: Faculty of Agriculture, Ibaraki University, Ibaraki 300-0393, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ohkubo
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Anthony
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA. Electronic address: dridi@uark.edu.
authors.forename: Sami
authors.initials: S
authors.lastname: Dridi
mesh_terms: D000447:Aldehydes / Q000494:pharmacology; D000818:Animals; D045744:Cell Line, Tumor; D003370:Coturnix; D015536:Down-Regulation / Q000187:drug effects; D018869:Heat-Shock Response / Q000235:genetics; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008099:Liver / Q000378:metabolism*; D008297:Male; D064446:Orexin Receptors / Q000235:genetics* / Q000378:metabolism; D000068797:Orexins / Q000235:genetics* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics
chemical_list: D000447:Aldehydes; D064446:Orexin Receptors; D000068797:Orexins; D006861:Hydrogen Peroxide; C027576:4-hydroxy-2-nonenal
keywords: Heat stress; Liver; Orexin; Oxidative stress