title: Organization of cholinergic systems in the brain of different fish groups: a comparative analysis.
abstract: Using choline acetyltransferase immunocytochemistry, we compared the cholinergic systems of the brains of four groups of fishes (lampreys, elasmobranchs, chondrosteans, and teleosts). Cholinergic nuclei were classified in four groups according to their distribution in vertebrates. The cranial motor nuclei and the habenulo-interpeduncular system were cholinergic in all vertebrates. The cholinergic nuclei of the isthmus of fishes showed many similarities with those of tetrapods. The magnocellular preoptic neurosecretory cells were cholinergic in most fishes, whereas in neurosecretory nuclei of tetrapods, cholinergic cells were only observed adjacent to the magnocellular cells. In the subpallium, cholinergic cells were observed in all fishes, with the exception of elasmobranchs, which suggests that they might be secondarily lost. In the pallium of fishes, cholinergic neurons were only observed in elasmobranchs. Because pallial cholinergic cells were only observed in lizard and mammals, they could have appeared several times during evolution. The same is suggested for the presence of cholinergic cells in the optic tectum of only a few vertebrate groups, including teleosts. This preliminary analysis enlarges our knowledge of the cholinergic systems of fishes, although more species and groups need to be studied to provide a more complete scenario of their evolution.
authors.affiliation: Department of Fundamental Biology, University of Santiago de Compostela, Santiago de Compostela, Spain. bfmoldes@usc.es
authors.forename: Isabel
authors.initials: I
authors.lastname: Rodríguez-Moldes
authors.forename: Pilar
authors.initials: P
authors.lastname: Molist
authors.forename: Fátima
authors.initials: F
authors.lastname: Adrio
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Pombal
authors.forename: Silvia Eva PérezJulián
authors.initials: SE
authors.lastname: Yáñez
authors.forename: Mónica
authors.initials: M
authors.lastname: Mandado
authors.forename: Oscar
authors.initials: O
authors.lastname: Marín
authors.forename: Jesús M
authors.initials: JM
authors.lastname: López
authors.forename: Agustín
authors.initials: A
authors.lastname: González
authors.forename: Ramón
authors.initials: R
authors.lastname: Anadón
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000166:cytology / Q000502:physiology*; D002799:Cholinergic Fibers / Q000502:physiology*; D004284:Dogfish; D005399:Fishes / Q000502:physiology*; D007150:Immunohistochemistry; D007798:Lampreys; D014018:Tissue Distribution; D014337:Trout
chemical_list: D000110:Acetylcholinesterase