title: Transient coupling of NMDA receptor with ip3 production in cultured cells of the avian retina.
abstract: The mobilization of inositol triphosphate ip3 by N-methyl D-aspartate (NMDA) and kainate, two excitatory amino acid EAA receptor agonists, was studied in cultured chick retina cells as a function of culture differentiation. Kainate (EC50 = 30 microM) stimulated from 6 to 9-fold the production of [3H]ip3 between E8C3 (embryonic day 8 plus 3 days in vitro) and E8C13. The kainate response was blocked by CNQX (100 microM) by more than 80% until stage E8C9. MK-801, however, was totally ineffective in preventing the kainate induced ip3 generation. [3H]ip3 production evoked by NMDA was increased 4-fold above basal levels at E8C3. As cultures differentiated, [3H]ip3 production promoted by NMDA decreased to 2.5-fold at E8C6 to 1.6-fold the basal levels in cultures at later stages of differentiation. The removal of Mg2+ from the incubating medium at E8C3 increased the NMDA mediated [3H]ip3 production by 80%. However, at more differentiated stages of the cultures, when cells were not responsive to NMDA, removal of Mg2+ plus the addition of 1 mM glycine did not change the pattern of the response. Although NMDA mediated ip3 production is almost absent in more differentiated cultures, NMDA is able to induce [3H]GABA release in E8C3 and E8C13 cultures with characteristics that reflect typical NMDA receptor activation: it is highly potentiated by the absence of Mg2+ and by the presence of glycine. The NMDA induced production of [3H]ip3 at E8C3 was entirely blocked by MK-801 (100 microM) and APV (100 microM) but not by CNQX.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Laboratório de Neuroquímica, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil.
authors.forename: R A
authors.initials: RA
authors.lastname: Reis
authors.forename: R C
authors.initials: RC
authors.lastname: Kubrusly
authors.forename: M C
authors.initials: MC
authors.lastname: de Mello
authors.forename: F G
authors.initials: FG
authors.lastname: de Mello
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis*; D007608:Kainic Acid / Q000494:pharmacology*; D016202:N-Methylaspartate / Q000494:pharmacology*; D009498:Neurotoxins / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D009498:Neurotoxins; D016194:Receptors, N-Methyl-D-Aspartate; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015544:Inositol 1,4,5-Trisphosphate; D007608:Kainic Acid