title: Daily rhythms in activity and mRNA abundance of enzymes involved in glucose and lipid metabolism in liver of rainbow trout, Oncorhynchus mykiss. Influence of light and food availability.
abstract: The present research aimed to investigate in a model of teleost fish (rainbow trout) the existence of daily changes in activity and mRNA abundance of several proteins involved in major pathways of carbohydrate and lipid metabolism in liver, and to test whether or not both the light-dark cycle and food availability might influence such rhythms. For this purpose, four cohorts of animals previously adapted to normal housing conditions (12L:12D; Lights on at ZT0; feeding time at ZT2) were subjected to: normal conditions (LD); 48-h constant darkness (DD); 96-h food deprivation (LD + Fasting); or constant darkness and food deprivation (DD + Fasting) respectively. After such time periods, fish were sacrificed and sampled every 4-h on the following 24-h period (ZT/CT0, 4, 8, 12, 16, 20 and 0'). Our results reveal that cortisol and all the analysed genes (gk, pepck, g6pase, pk, glut2, hoad and fas) exhibited well defined daily rhythms, which persisted even in the absence of light and/or food indicating the endogenous nature of such rhythms. Even when the variations of enzyme activities were not significant, their rhythms mostly paralleled those of the respective gene expression. The rhythms of mRNA abundance were apparently dependent on the presence of food, but the light/dark cycle also influenced such rhythms. Since cortisol does not appear to be mainly involved in generating such daily rhythms in liver, alternative mechanisms might be involved, such as a direct interaction between metabolism and the circadian system.
authors.affiliation: a Laboratorio de Fisioloxía Animal , Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo , Vigo (Pontevedra) , Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Hernández-Pérez
authors.affiliation: a Laboratorio de Fisioloxía Animal , Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo , Vigo (Pontevedra) , Spain.
authors.forename: Jesús M
authors.initials: JM
authors.lastname: Míguez
authors.affiliation: a Laboratorio de Fisioloxía Animal , Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo , Vigo (Pontevedra) , Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Librán-Pérez
authors.affiliation: a Laboratorio de Fisioloxía Animal , Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo , Vigo (Pontevedra) , Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Otero-Rodiño
authors.affiliation: a Laboratorio de Fisioloxía Animal , Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo , Vigo (Pontevedra) , Spain.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Naderi
authors.affiliation: a Laboratorio de Fisioloxía Animal , Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo , Vigo (Pontevedra) , Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Soengas
authors.affiliation: a Laboratorio de Fisioloxía Animal , Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo , Vigo (Pontevedra) , Spain.
authors.forename: Marcos A
authors.initials: MA
authors.lastname: López-Patiño
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D005247:Feeding Behavior / Q000502:physiology*; D005502:Food; D005947:Glucose / Q000378:metabolism*; D008027:Light; D008099:Liver / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000378:metabolism; D017440:Photoperiod; D012333:RNA, Messenger / Q000378:metabolism*; D013997:Time Factors
chemical_list: D012333:RNA, Messenger; D005947:Glucose
keywords: Rhythms; carbohydrate metabolism; circadian.; lipid metabolism; rainbow trout