title: Functional expression of ionotropic glutamate receptors in the rabbit retinal ganglion cells.
abstract: It has been known that retinal ganglion cells (RGCs) with distinct morphologies have different physiological properties. It was hypothesized that different functions of RGCs may in part result from various expressions of N-methyl-d-aspartate (NMDA), α-amino-3-hydroxyl-5-methyl-isoxazole-4-propinoic acid (AMPA), and kainic acid (KA) receptors on their dendrites. In the present study, we aimed to characterize the functional expression of AMPA and NMDA receptors of morphologically identified RGCs in the wholemount rabbit retina. The agmatine (AGB) activation assay was used to reveal functional expression of ionotropic glutamate receptors after the RGCs were targeted by injecting Neurobiotin. To examine the excitability of these glutamate receptors in an agonist specific manner, the lower concentrations of AMPA (2 μM) and NMDA (100 μM) were chosen to examine G7 (ON-OFF direction selective ganglion cells) and G11 (alpha ganglion cells) types of RGCs. We found that less than 40% of G7 type RGCs had salient AGB activation when incubated with 2 μM AMPA or 100 μM NMDA. The G11 type RGCs also showed similar activation frequencies, except that all of the OFF subtype examined had no AGB permeation under the same AMPA concentration. These results suggest that RGCs with large somata (G7 and G11 types) may express various heterogeneous functional ionotropic glutamate receptors, thus in part rendering their functional diversity.
authors.affiliation: Department of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan; Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Yin-Peng
authors.initials: YP
authors.lastname: Chen
authors.forename: Chuan-Chin
authors.initials: CC
authors.lastname: Chiao
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D016202:N-Methylaspartate / Q000494:pharmacology; D009924:Organ Culture Techniques; D011817:Rabbits; D018091:Receptors, AMPA / Q000187:drug effects / Q000502:physiology; D058468:Receptors, Ionotropic Glutamate / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
chemical_list: D018690:Excitatory Amino Acid Agonists; D016202:N-Methylaspartate; D018091:Receptors, AMPA; D058468:Receptors, Ionotropic Glutamate; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid