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Titolo:
Responses of directionally selective retinal ganglion cells to activation of AMPA glutamate receptors
Autore:
Jensen, RJ;
Indirizzi:
So Coll Optometry, Dept Biomed Sci, Memphis, TN 38104 USA So Coll Optometry Memphis TN USA 38104 Biomed Sci, Memphis, TN 38104 USA
Titolo Testata:
VISUAL NEUROSCIENCE
fascicolo: 2, volume: 16, anno: 1999,
pagine: 205 - 219
SICI:
0952-5238(199903/04)16:2<205:RODSRG>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHOLINERGIC AMACRINE CELLS; RAT HIPPOCAMPAL-NEURONS; K+ CHANNEL OPENERS; RABBIT RETINA; KAINATE RECEPTORS; MAMMALIAN RETINA; ACETYLCHOLINE-RELEASE; GABA(C) RECEPTORS; DESENSITIZATION; CYCLOTHIAZIDE;
Keywords:
directional selectivity; rabbit retinal ganglion cells; AMPA glutamate receptors;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
65
Recensione:
Indirizzi per estratti:
Indirizzo: Jensen, RJ So Coll Optometry, Dept Biomed Sci, 1245 Madison Ave, Memphis, TN 38104 USA So Coll Optometry 1245 Madison Ave Memphis TN USA 38104 104 USA
Citazione:
R.J. Jensen, "Responses of directionally selective retinal ganglion cells to activation of AMPA glutamate receptors", VIS NEUROSC, 16(2), 1999, pp. 205-219

Abstract

Previous studies in the rabbit retina have shown that drugs which block AMPA glutamate receptors abolish directional selectivity in ON-OFF directionally selective (DS) ganglion cells. The effects of activation of AMPA receptors on the directionally selective responses of these ganglion cells had not been studied. In the present study, extracellular recordings of the responses of ON-OFF DS ganglion cells to a moving bar of light were made in an in vitro rabbit retinal preparation. In control solution, bath application of AMPA (7-10 mu M) abolished the light responses of most ON-OFF DS ganglioncells. On washout of AMPA, the light responses rapidly returned; however, the cells temporarily lost the ability to discriminate the direction of themoving bar of light. That is, the cells responded equally to movement in the preferred and null directions. Pretreatment of retinas with the glycine receptor antagonist strychnine (1-2 mu M) did not alter the effects of AMPA. On the other hand, in retinas pretreated with the GABAA receptor antagonist SR95531 (0.2-0.25 mu M), AMPA did not abolish the light responses of ON-OFF DS ganglion cells but instead abolished directional selectivity in these cells by bringing out a response to movement in the null direction. This finding suggests that an AMPA-induced GABA efflux from cells in the retina was responsible for the suppression of the light responses by AMPA. In control solution, application of the selective AMPA receptor agonist (S)-5-fluorowillardiine (2-3 mu M) only temporarily abolished the light responses of ON-OFF DS ganglion cells. As the light responses returned, it was clear that directional selectivity had been abolished by (S)-5-fluorowillardiine. Tncontrol solution, blocking AMPA receptor desensitization with cyclothiazide (80-100 mu M) greatly reduced the light responses of ON-OFF DS ganglion cells. As the light responses slowly returned on washout of cyclothiazide, directional selectivity was clearly reduced although not abolished. In retinas pretreated with SR95531, application of cyclothiazide abolished directional selectivity. Diazoxide (700-1000 mu M), another blocker of AMPA receptor desensitization, abolished directional selectivity in ON-OFF DS ganglion cells without the need of adding SR95531 to the bathing solution. It is concluded that, in the rabbit retina, AMPA receptors play an important role ingenerating directional selectivity in ON-OFF DS ganglion cells. Moreover, excessive activation of AMPA receptors greatly compromises the mechanism for directional selectivity in ON-OFF DS ganglion cells.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 07:16:26