title: GABA(Abeta2-3) immunoreactive cells in the developing chick retina.
abstract: Gama-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS). It has been shown that GABA is an important factor for CNS maturation and that its functions are mainly mediated by GABA(A) receptors. Thus, in order to fully comprehend the role of GABA during development, it is essential to establish the developmental features of the catalytic subunits (beta) of GABA(A) receptor. Here, we determine the ontogenesis and neurogenesis of cells expressing beta2-3 subunits of GABA(A) receptor (GABA(Abeta2-3)) in the chick retina. In the ontogenetic experiments, only the immunohistochemistry for GABA(Abeta2-3) approach was employed. For neurogenesis a double-labeling method (autoradiography and immunohistochemistry) was applied. [H(3)]-thymidine was injected into eggs (2-11 days) and the embryos were sacrificed at embryonic day 19 (E19). GABA(Abeta2-3) immunohistochemistry was processed and then autoradiography was performed. We used a cumulative counting method to quantify the autoradiographic grains. The ontogenesis study revealed that at E9, GABA(Abeta2-3) immunoreactivity was restricted to the inner plexiform layer and the first cell bodies immunoreactive to GABA(Abeta2-3) were seen at E14. Thereafter, the number of cell bodies and the intensity of GABA(Abeta2-3) immunoreactivity increased until the adult pattern was established. The neurogenesis study showed that cells that will express GABA(Abeta2-3) were generated between E6 and E9. In addition, from E7 to E9 the rate of neurogenesis of GABA(Abeta2-3) immunoreactive cells quickly increases. Therefore, the detection of GABA(Abeta2-3) occurred only after the end of generation period of this cell population.
authors.affiliation: Lab. Neurobiologia da Retina, Depto Neurobiologia, Instituto de Biofísica Carlos Chagas Filho, Cidade Universitária, CCS, Bloco G, UFRJ, RJ 21949-900, Rio de Janeiro, Brazil.
authors.forename: Pedro Henrique Oliveira Cavalcanti
authors.initials: PH
authors.lastname: Barros
authors.forename: Karin da Costa
authors.initials: Kda C
authors.lastname: Calaza
authors.forename: Patrícia Franca
authors.initials: PF
authors.lastname: Gardino
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002642:Chick Embryo; D002645:Chickens; D011963:Receptors, GABA-A / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D011963:Receptors, GABA-A