title: Morphogenesis in the retina of a slow-developing teleost: emergence of the GABAergic system in relation to cell proliferation and differentiation.
abstract: Gamma-aminobutyric acid (GABA) has been implicated in cell proliferation and differentiation during development. In the present study, immunohistochemical techniques were used to investigate the development of the GABAergic system in the retina of the trout and its relation to markers of differentiation [calretinin (CR), and tyrosine hydroxylase (TH)]. The expression of Pax6, an eye-patterning protein involved in the proliferation and emergence of specific retinal cell types, was also studied. Retinal layering was observed to begin centrally in prehatching embryos, as the first GABAergic cells appeared in the ganglion cell layer (GCL) and inner part of the inner nuclear layer (INL). At hatching, GABAergic cells were also observed in the horizontal cell layer (HCL). In alevins, GABAergic cells and processes spread laterally following retinal growth although they did not invade neuroblastic retinal regions. CR- and Pax6-immunoreactive (ir) cells were first seen in the GCL and the inner part of the INL, whereas sparse TH-ir cells appeared in the INL. In juveniles, GABAergic cells were observed in the GCL, inner part of the INL and HCL, whereas CR-ir cells spread to the outer part of the INL and HCL. A subset of CR-ir in the GCL and of Pax6-ir cells in the GCL and INL showed colocalization with GABAergic markers. This study provides further comparative knowledge about the development of GABAergic system of the retina in teleosts and shows differences and similarities with that reported in fast-developing species such as zebrafish, in which retinal expression of GABA was transient in some populations.
authors.affiliation: Department of Cell Biology and Ecology, Faculty of Biology, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. ecandal@usc.es
authors.forename: Eva
authors.initials: E
authors.lastname: Candal
authors.forename: Susana
authors.initials: S
authors.lastname: Ferreiro-Galve
authors.forename: Ramón
authors.initials: R
authors.lastname: Anadón
authors.forename: Isabel
authors.initials: I
authors.lastname: Rodríguez-Moldes
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D064032:Calbindin 2; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation; D004625:Embryo, Nonmammalian; D005136:Eye Proteins / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D009474:Neurons / Q000502:physiology*; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000196:embryology / Q000254:growth & development; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D014337:Trout / Q000033:anatomy & histology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D029961:Zebrafish Proteins; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D064032:Calbindin 2; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D064030:S100 Calcium Binding Protein G; D029961:Zebrafish Proteins; C576513:calb2b protein, zebrafish; D005680:gamma-Aminobutyric Acid; D014446:Tyrosine 3-Monooxygenase; D005968:Glutamate Decarboxylase