Ionotropic glutamate receptors of amacrine cells of the mouse retina

Abstract

The mammalian retina contains approximately 30 different morphological types of amacrine cells, receiving glutamatergic input from bipolar cells. In this study, we combined electrophysiological and pharmacological techniques in order to study the glutamate receptors expressed by different types of amacrine cells. Whole-cell currents were recorded from amacrine cells in vertical slices of the mouse retina. During the recordings the cells were filled with Lucifer Yellow0Neurobiotin allowing classification as wide-field or narrow-field amacrine cells. Amacrine cell recordings were also carried out in a transgenic mouse line whose glycinergic amacrine cells express enhanced green fluorescent protein~EGFP!. Agonist-induced currents were elicited by exogenous application of NMDA, AMPA, and kainate~KA! while holding cells at Ϫ75 mV. Using a variety of specific agonists and antagonists~NBQX, AP5, cyclothiazide, GYKI 52466, GYKI 53655, SYM 2081! responses mediated by AMPA, KA, and NMDA receptors could be dissected. All cells~n ϭ 300! showed prominent responses to non-NMDA agonists. Some cells expressed AMPA receptors exclusively and some cells expressed KA receptors exclusively. In the majority of cells both receptor types could be identified. NMDA receptors were observed in about 75% of the wide-field amacrine cells and in less than half of the narrow-field amacrine cells. Our results confirm that different amacrine cell types express distinct sets of ionotropic glutamate receptors, which may be critical in conferring their unique temporal responses to this diverse neuronal class.

Mechanisms Underlying Lateral GABAergic Feedback onto Rod Bipolar Cells in Rat Retina

“…Amacrine cells receive glutamatergic inputs from bipolar cells and express various subtypes of glutamate receptors (Dixon and Copenhagen, 1992; Euler et al, 1996; Dumitrescu et al, 2006). GABAergic A17 amacrine cells receive excitatory input via CP-AMPARs (Chavez et al, 2006), but glycinergic amacrine cells that contact RBCs are driven by NMDA and Ca 2+ -impermeable AMPARs (Chavez and Diamond, 2008).…”

Mapping kainate activation of inner neurons in the rat retina

“…In the rabbit retina, AII ACs also contributed most to the glycinergic AC response (Marc, 1999a). Dumitrescu et al (2006) showed that 77% of mice AII ACs possessed AMPA- and KA-responsive glutamate receptors but AII ACs did not express KA-responsive glutamate receptors exclusively. Electrophysical recordings from the rat and rabbit retina also indicate that AII ACs only possess functional AMPA receptors (Morkve et al, 2002; Veruki et al, 2003; Zhou and Dacheux, 2004).…”

Functional architecture of the retina: Development and disease

“…In rat retina, amacrine cells receive excitatory input from bipolar cell terminals at iGluR synapses but different amacrine cell subsets express different compositions of iGluR (Nivison-Smith et al, 2013). Recordings in mouse retina have revealed that the majority of amacrine cells show both AMPA and Kainate receptor-mediated responses, with a small fraction showing only AMPA or only Kainate-mediated responses (Dumitrescu et al, 2006). …”