Excitatory amino acid receptors on sustained retinal ganglion cells in the kitten during the critical period of development.
Effects of iontophoretically applied excitatory amino acid analogues, kainate, quisqualate and N-methyl-D-aspartate (NMDA) and their receptor antagonists on the sustained class of retinal ganglion cells were studied in the optically intact eye of pentobarbitone-anaesthetized kittens (7-9 weeks of age). These results were compared with the effects obtained in adult cats. All 3 excitatory amino acid agonists had excitatory actions on the majority of On- and Off-sustained ganglion cells in the kitten but at higher current levels than those required for adult cells, suggesting all 3 types of receptors of weaker sensitivity are present on the kitten cells. Whilst the relative potency of kainate, quisqualate and NMDA was 15:3:1 in the adult cells, it was 5:2:1 in the kitten cells. As for other neurones in the CNS, an increase in the potency of kainate receptors and a decrease in that of NMDA receptors appear, therefore, to characterize the postnatal development of the excitatory amino acid receptors on the retinal ganglion cells. In accordance with the agonist results, a broadband receptor antagonist, kynurenate, powerfully antagonised responses of kitten cells as well as those of adult cells. The pure NMDA receptor antagonist, 3((+-)-2-carboxypiperazin-4-yl)propyl-1-phosphonate (CPP), however, only suppressed spontaneous firing of kitten cells. Furthermore, in kitten cells, the visually-driven firing was depressed while the level of firing was raised by these excitatory amino acid analogous, and a long period of inhibition of firing followed the agonist-induced excitation.(ABSTRACT TRUNCATED AT 250 WORDS)
Ikeda
H
H
Vision Research Unit of Sherrington School, Rayne Institute, St. Thomas' Hospital, London, U.K.
Robbins
J
J
Kay
C D
CD
D000200:Action Potentials / Q000187:drug effects; D000375:Aging / Q000502:physiology*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D002415:Cats; D007608:Kainic Acid / Q000494:pharmacology*; D016202:N-Methylaspartate; D010069:Oxadiazoles / Q000494:pharmacology; D010775:Photic Stimulation; D016318:Quisqualic Acid; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000502:physiology*; D012160:Retina / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*
D010069:Oxadiazoles; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D001224:Aspartic Acid; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D007608:Kainic Acid