Immunocytochemical localization of the NMDA-R2A receptor subunit in the cat retina

Immunocytochemical localization of the NMDA-R2A receptor subunit in the cat retina Immunocytochemical studies were performed to determine the distribution and cellular localization of the NMDA-R2A receptor subunit (R2A) in the cat retina. R2A-immunoreactivity (R2A-IR) was noted in all layers of the retina, with specific localizations in the outer segments of red/green and blue cone photoreceptors, B-type horizontal cells, several types of amacrine cells, Müller cells and the majority of cells in the ganglion cell layer. In the inner nuclear layer, 48% of all cells residing in the amacrine cell layer were R2A-IR including a cell resembling the GABAergic A17 amacrine cell. Interestingly, the AII rod amacrine cell was devoid of R2A-IR. Although the localization of the R2A subunit was anticipated in ganglion cells, amacrines and Müller cells, the presence of this receptor subunit to the cells in the outer retina was not expected. Here, both the R2A and the R2B subunits were found to be present in the outer segments of cone photoreceptors and to the tips of rod outer segments. Although the function of these receptor subunits in rod and cone photoreceptors remains to be determined, the fact that both R2A and R2B receptor subunits are localized to cone outer segments suggests a possible alternative pathway for calcium entry into a region where this cation plays such a crucial role in the process of phototransduction. To further classify the cells that display NR2A-IR, we performed dual labeling experiments showing the relationship between R2A-labeled cells with GABA. Results showed that all GABAergic-amacrines and displaced amacrines express the R2A-subunit protein. In addition, approximately 11% of the NR2A-labeled amacrines, did not stain for GABA. These findings support pharmacological data showing that NMDA directly facilitates GABA release in retina and retinal cultures (I.L. Ferreira, C.B. Duarte, P.F. Santos, C.M. Carvalho, A.P. Carvalho, Release of ( 3 H ) GABA evoked by glutamate receptor agonist in cultured chick retinal cells: effect of Ca 2+ , Brain Res. 664 (1994) 252–256; G.D. Zeevalk, W.J. Nicklas, Action of the anti-ischemic agent ifenprodil on N -methyl- d -aspartate and kainate-mediated excitotoxicity, Brain Res. 522 (1990) 135–139; R. Huba, H.D. Hofmann, Transmitter-gated currents of GABAergic amacrine-like cells in chick retinal cultures, Vis. Neurosci. 6 (1991) 303–314; M. Yamashita, R. Huba, H.D. Hofmann, Early in vitro development of voltage- and transmitter-gated currents in GABAergic amacrine cells, Dev. Brain Res. 82 (1994) 95–102; R. Ientile, S. Pedale, V. Picciurro, V. Macaione, C. Fabiano, S. Macaione, Nitric oxide mediates NMDA-evoked (3H)GABA release from chick retina cells, FEBS Lett. 417 (1997) 345–348; R.C. Kubrusly, M.C. deMello, F.G. deMello, Aspartate as a selective NMDA agonist in cultured cells from the avian retina, Neurochem. Intl. 32 (1998) 47–52) or reduction of GABA in vivo (N.N. Osborn, A.J. Herrera, The effect of experimental ischaemia and excitatory amino acid agonist on the GABA and serotonin immunoreactivities in the rabbit retina, Neurosci. 59 (1994) 1071–1081). Since the majority of GABAergic synapses in the inner retina are onto both rod and cone bipolar axon terminals (R.G. Pourcho, M.T. Owzcarzak, Distribution of GABA immunoreactivity in the cat retina: A light and electron-microscopic study, Vis. Neurosci. 2 (1989) 425–435), we hypothesize that the NMDA-receptor plays a crucial role in providing feedback inhibition onto rod and cone bipolar cells. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Brain Research Elsevier

Immunocytochemical localization of the NMDA-R2A receptor subunit in the cat retina

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Publisher
Elsevier
Copyright
Copyright © 1998 Elsevier Science B.V.
ISSN
0006-8993
D.O.I.
10.1016/S0006-8993(98)00749-5
Publisher site
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Abstract

Immunocytochemical studies were performed to determine the distribution and cellular localization of the NMDA-R2A receptor subunit (R2A) in the cat retina. R2A-immunoreactivity (R2A-IR) was noted in all layers of the retina, with specific localizations in the outer segments of red/green and blue cone photoreceptors, B-type horizontal cells, several types of amacrine cells, Müller cells and the majority of cells in the ganglion cell layer. In the inner nuclear layer, 48% of all cells residing in the amacrine cell layer were R2A-IR including a cell resembling the GABAergic A17 amacrine cell. Interestingly, the AII rod amacrine cell was devoid of R2A-IR. Although the localization of the R2A subunit was anticipated in ganglion cells, amacrines and Müller cells, the presence of this receptor subunit to the cells in the outer retina was not expected. Here, both the R2A and the R2B subunits were found to be present in the outer segments of cone photoreceptors and to the tips of rod outer segments. Although the function of these receptor subunits in rod and cone photoreceptors remains to be determined, the fact that both R2A and R2B receptor subunits are localized to cone outer segments suggests a possible alternative pathway for calcium entry into a region where this cation plays such a crucial role in the process of phototransduction. To further classify the cells that display NR2A-IR, we performed dual labeling experiments showing the relationship between R2A-labeled cells with GABA. Results showed that all GABAergic-amacrines and displaced amacrines express the R2A-subunit protein. In addition, approximately 11% of the NR2A-labeled amacrines, did not stain for GABA. These findings support pharmacological data showing that NMDA directly facilitates GABA release in retina and retinal cultures (I.L. Ferreira, C.B. Duarte, P.F. Santos, C.M. Carvalho, A.P. Carvalho, Release of ( 3 H ) GABA evoked by glutamate receptor agonist in cultured chick retinal cells: effect of Ca 2+ , Brain Res. 664 (1994) 252–256; G.D. Zeevalk, W.J. Nicklas, Action of the anti-ischemic agent ifenprodil on N -methyl- d -aspartate and kainate-mediated excitotoxicity, Brain Res. 522 (1990) 135–139; R. Huba, H.D. Hofmann, Transmitter-gated currents of GABAergic amacrine-like cells in chick retinal cultures, Vis. Neurosci. 6 (1991) 303–314; M. Yamashita, R. Huba, H.D. Hofmann, Early in vitro development of voltage- and transmitter-gated currents in GABAergic amacrine cells, Dev. Brain Res. 82 (1994) 95–102; R. Ientile, S. Pedale, V. Picciurro, V. Macaione, C. Fabiano, S. Macaione, Nitric oxide mediates NMDA-evoked (3H)GABA release from chick retina cells, FEBS Lett. 417 (1997) 345–348; R.C. Kubrusly, M.C. deMello, F.G. deMello, Aspartate as a selective NMDA agonist in cultured cells from the avian retina, Neurochem. Intl. 32 (1998) 47–52) or reduction of GABA in vivo (N.N. Osborn, A.J. Herrera, The effect of experimental ischaemia and excitatory amino acid agonist on the GABA and serotonin immunoreactivities in the rabbit retina, Neurosci. 59 (1994) 1071–1081). Since the majority of GABAergic synapses in the inner retina are onto both rod and cone bipolar axon terminals (R.G. Pourcho, M.T. Owzcarzak, Distribution of GABA immunoreactivity in the cat retina: A light and electron-microscopic study, Vis. Neurosci. 2 (1989) 425–435), we hypothesize that the NMDA-receptor plays a crucial role in providing feedback inhibition onto rod and cone bipolar cells.

Journal

Brain ResearchElsevier

Published: Oct 19, 1998

References

  • Roles of aspartate and glutamate in synaptic transmission in rabbit retina: II. Inner Plexiform Layer
    Bloomfield, S.A.; Dowling, J.E.
  • Actions of excitatory amino acids on brisk ganglion cells in the cat retina
    Boos, R.; Muller, F.; Wässle, H.
  • Expression of NMDA and high-affinity kainate receptor subunit mRNAs in the adult rat retina
    Brandstätter, J.H.; Hartveit, E.; Sassoe-Pognetto, M.; Wässle, H.
  • Aspartate as a selective NMDA agonist in cultured cells from the avian retina
    Kubrusly, R.C.; deMello, M.C.; deMello, F.G.
  • Excitatory amino acid receptors of rod- and cone-driven horizontal cells in the rabbit retina
    Massey, S.C.; Miller, R.F.
  • N -Methyl- d -Aspartate receptors of ganglion cells in rabbit retina
    Massey, S.C.; Miller, R.F.
  • The excitatory amino acid receptors: Their classes, pharmacology, and distinct properties in the function of the central nervous system
    Monaghan, D.T.; Bridges, R.J.; Cotman, C.W.
  • A voltage-clamp study of isolated stingray horizontal cell non-NMDA excitatory amino acid receptors
    O'Dell, T.J.; Christensen, B.N.
  • Distribution of AMPA-selective glutamate receptor subunits in the cat retina
    Qin, P.; Pourcho, R.G.

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