title: Cholecystokinin impact on rainbow trout glucose homeostasis: possible involvement of central glucosensors.
abstract: Although the role of cholecystokinin (CCK) on fish appetite regulation has been widely studied, its involvement in the regulation of glucose metabolism had been little explored to date. In the present study we have carried out different experimental approaches to study CCK effects in rainbow trout (a so-called 'glucose intolerant' fish species) glucose homeostasis. We have found that for the first time in a vertebrate species, systemic or central CCK administration causes hyperglycemia, which is at least in part related to the presence of an ancestral gut-brain axis in which CCK is involved. By using capsaicin we have found that part of the action of CCK on glucose homeostasis is mediated by vagal and splanchnic afferents. Changes in hepatic metabolism after systemic CCK administration suggest that the effects are not directly taking place on the liver, but probably in other tissues, while after the central CCK administration, the glycogenolytic response observed in liver could be mediated by the activation of the sympathetic system. In hypothalamus and hindbrain changes elicited by CCK-8 treatment are likely related to the glucosensor response to the increased glycemia and/or vagal/splanchnic afferences whereas in hindbrain a possible action through specific CCK-1 receptors cannot be excluded. All these processes result in changes in metabolic parameters related with glucose homeostasis control. Further studies are needed to fully understand the role of this peptide on glucose homeostasis control in fish.
authors.affiliation: Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, 36310 Vigo, Spain. spolakof@uvigo.es
authors.forename: Sergio
authors.initials: S
authors.lastname: Polakof
authors.forename: Jesus M
authors.initials: JM
authors.lastname: Míguez
authors.forename: José L
authors.initials: JL
authors.lastname: Soengas
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002766:Cholecystokinin / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D006706:Homeostasis / Q000187:drug effects; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology
chemical_list: D010446:Peptide Fragments; C410885:cholecystokinin 8; D002766:Cholecystokinin; D005947:Glucose