title: The turtle thalamic anterior entopeduncular nucleus shares connectional and neurochemical characteristics with the mammalian thalamic reticular nucleus.
abstract: Neurochemical and key connectional characteristics of the anterior entopeduncular nucleus (Enta) of the turtle (Testudo horsfieldi) were studied by axonal tracing techniques and immunohistochemistry of parvalbumin, gamma-aminobutyric acid (GABA) and glutamic acid decarboxylase (GAD). We showed that the Enta, which is located within the dorsal peduncle of the lateral forebrain bundle (Pedd), has roughly topographically organized reciprocal connections with the dorsal thalamic visual nuclei, the nucleus rotundus (Rot) and dorsal lateral geniculate nucleus (GLd). The Enta receives projections from visual telencephalic areas, the anterior dorsal ventricular ridge and dorsolateral cortex/pallial thickening. Most Enta neurons contained GABA and parvalbumin, and some of them were retrogradely labeled when the tracer was injected into the visual dorsal thalamic nuclei. Further experiments using double immunofluorescence revealed colocalization of GAD and parvalbumin in the vast majority of Enta neurons, and many of these cells showed retrograde labeling with Fluoro-gold injected into the Rot and/or GLd. According to these data, the Enta may be considered as a structural substrate for recurrent inhibition of the visual thalamic nuclei. Based on morphological and neurochemical similarity of the turtle Enta, caiman Pedd nucleus, the superior reticular nucleus in birds, and the thalamic reticular nucleus in mammals, we suggest that these structures represent a characteristic component which is common to the thalamic organization in amniotes.
authors.affiliation: Muséum National d'Histoire Naturelle USM-0501, Centre National de la Recherche Scientifique UMR-5166, Bat. d'Anatomie comparée, Paris, France.
authors.forename: Natalia
authors.initials: N
authors.lastname: Kenigfest
authors.forename: Margarita
authors.initials: M
authors.lastname: Belekhova
authors.forename: Jacques
authors.initials: J
authors.lastname: Repérant
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Rio
authors.forename: Roger
authors.initials: R
authors.lastname: Ward
authors.forename: Nikolai
authors.initials: N
authors.lastname: Vesselkin
mesh_terms: D000489:Alligators and Crocodiles / Q000033:anatomy & histology / Q000378:metabolism; D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000033:anatomy & histology / Q000378:metabolism; D005829:Geniculate Bodies / Q000033:anatomy & histology / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007150:Immunohistochemistry; D020646:Intralaminar Thalamic Nuclei / Q000033:anatomy & histology* / Q000378:metabolism; D008322:Mammals / Q000033:anatomy & histology / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D010802:Phylogeny; D013266:Stilbamidines; D013687:Telencephalon / Q000033:anatomy & histology / Q000378:metabolism; D013787:Thalamic Nuclei / Q000033:anatomy & histology* / Q000378:metabolism; D014426:Turtles / Q000033:anatomy & histology* / Q000378:metabolism; D014793:Visual Cortex / Q000033:anatomy & histology / Q000378:metabolism; D014795:Visual Pathways / Q000033:anatomy & histology* / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D010320:Parvalbumins; D013266:Stilbamidines; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase