title: Roles of leptin and ghrelin in adipogenesis and lipid metabolism of rainbow trout adipocytes in vitro.
abstract: Leptin and ghrelin are important regulators of energy homeostasis in mammals, whereas their physiological roles in fish have not been fully elucidated. In the present study, the effects of leptin and ghrelin on adipogenesis, lipolysis and on expression of lipid metabolism-related genes were examined in rainbow trout adipocytes in vitro. Leptin expression and release increased from preadipocytes to mature adipocytes in culture, but did not affect the process of adipogenesis. While ghrelin and its receptor were identified in cultured differentiated adipocytes, ghrelin did not influence either preadipocyte proliferation or differentiation, indicating that it may have other adipose-related roles. Leptin and ghrelin increased lipolysis in mature freshly isolated adipocytes, but mRNA expression of lipolysis markers was not significantly modified. Leptin significantly suppressed the fatty acid transporter-1 expression, suggesting a decrease in fatty acid uptake and storage, but did not affect expression of any of the lipogenesis or β-oxidation genes studied. Ghrelin significantly increased the mRNA levels of lipoprotein lipase, fatty acid synthase and peroxisome proliferator-activated receptor-β, and thus appears to stimulate synthesis of triglycerides as well as their mobilization. Overall, the study indicates that ghrelin, but not leptin seems to be an enhancer of lipid turn-over in adipose tissue of rainbow trout, and this regulation may at least partly be mediated through autocrine/paracrine mechanisms. The mode of action of both hormones needs to be further explored to better understand their roles in regulating adiposity in fish.
authors.affiliation: Department of Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Salmerón
authors.affiliation: Fish Endocrinology Laboratory, Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg 40590, Sweden.
authors.forename: Marcus
authors.initials: M
authors.lastname: Johansson
authors.affiliation: Department of Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain.
authors.forename: Maryam
authors.initials: M
authors.lastname: Asaad
authors.affiliation: Department of Biology, University of Bergen, Bergen 5020, Norway.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Angotzi
authors.affiliation: Department of Biology, University of Bergen, Bergen 5020, Norway.
authors.forename: Ivar
authors.initials: I
authors.lastname: Rønnestad
authors.affiliation: Department of Biology, University of Bergen, Bergen 5020, Norway.
authors.forename: Sigurd O
authors.initials: SO
authors.lastname: Stefansson
authors.affiliation: Fish Endocrinology Laboratory, Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg 40590, Sweden.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Jönsson
authors.affiliation: Fish Endocrinology Laboratory, Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg 40590, Sweden.
authors.forename: Björn Thrandur
authors.initials: BT
authors.lastname: Björnsson
authors.affiliation: Department of Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gutiérrez
authors.affiliation: Department of Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Navarro
authors.affiliation: Department of Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona 08028, Spain. Electronic address: ecapilla@ub.edu.
authors.forename: Encarnación
authors.initials: E
authors.lastname: Capilla
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D050156:Adipogenesis / Q000187:drug effects / Q000235:genetics; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D015870:Gene Expression; D054439:Ghrelin / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D020738:Leptin / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects / Q000235:genetics; D018613:Microscopy, Confocal; D017686:Oncorhynchus mykiss / Q000235:genetics / Q000378:metabolism*; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D054440:Receptors, Ghrelin / Q000378:metabolism; D054411:Receptors, Leptin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D054439:Ghrelin; D020738:Leptin; D047495:PPAR gamma; D054440:Receptors, Ghrelin; D054411:Receptors, Leptin
keywords: Adipocyte primary culture; Adipose tissue; Differentiation; Ghrelin; Insulin; Isolated mature adipocytes; Leptin; Lipolysis; Proliferation