title: Counter-regulatory response to a fall in circulating fatty acid levels in rainbow trout. Possible involvement of the hypothalamus-pituitary-interrenal axis.
abstract: We hypothesize that a decrease in circulating levels of fatty acid (FA) in rainbow trout Oncorhynchus mykiss would result in the inhibition of putative hypothalamic FA sensing systems with concomitant changes in the expression of orexigenic and anorexigenic factors ultimately leading to a stimulation of food intake. To assess this hypothesis, we lowered circulating FA levels treating fish with SDZ WAG 994 (SDZ), a selective A1 adenosine receptor agonist that inhibits lipolysis. In additional groups, we also evaluated if the presence of intralipid was able to counteract changes induced by SDZ treatment, and the possible involvement of the hypothalamus-pituitary-interrenal (HPI) axis by treating fish with SDZ in the presence of metyrapone, which decreases cortisol synthesis in fish. The decrease in circulating levels of FA in rainbow trout induced a clear increase in food intake that was associated with the decrease of the anorexigenic potential in hypothalamus (decreased POMC-A1 and CART mRNA abundance), and with changes in several parameters related to putative FA-sensing mechanisms in hypothalamus. Intralipid treatment counteracted these changes. SDZ treatment also induced increased cortisol levels and the activation of different components of the HPI axis whereas these changes disappeared in the presence of intralipid or metyrapone. These results suggest that the HPI axis is involved in a counter-regulatory response in rainbow trout to restore FA levels in plasma.
authors.affiliation: Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, Vigo, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Librán-Pérez
authors.affiliation: Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, Vigo, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Velasco
authors.affiliation: Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, Vigo, Spain.
authors.forename: Marcos A
authors.initials: MA
authors.lastname: López-Patiño
authors.affiliation: Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, Vigo, Spain.
authors.forename: Jesús M
authors.initials: JM
authors.lastname: Míguez
authors.affiliation: Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, Vigo, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Soengas
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D017931:DNA Primers / Q000235:genetics; D005227:Fatty Acids / Q000097:blood*; D025461:Feedback, Physiological / Q000502:physiology*; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D007401:Interrenal Gland / Q000378:metabolism*; D008066:Lipolysis / Q000187:drug effects; D008797:Metyrapone; D017686:Oncorhynchus mykiss / Q000097:blood / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D005227:Fatty Acids; C090949:N(6)-cyclohexyl-2-O-methyladenosine; D000241:Adenosine; D006854:Hydrocortisone; D008797:Metyrapone