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S.L. Mills; Analysis of Coupling in a Complex Ganglion Cell/amacrine Cell Network . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2072.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Injection of Neurobiotin into an OFF alpha ganglion cell stains other alpha ganglion cells and a variety of amacrine cells. The distribution of tracer is not uniform, but constrained by the geometry of the retinal circuit. This distribution can reveal many details about the coupled circuit. Neurobiotin injection combined with pharmacological manipulation was used to analyze the details of this coupled network. Methods: OFF alpha ganglion cells of rabbit retina were visualized with acridine orange, injected with Neurobiotin and subsequently visualized with streptavidin-Cy3. Dopamine and cAMP analogs were used to modulate coupling. Rate constants for potential gap junctional pathways were calculated with a diffusion model. Results: Coupling between amacrine cells decreased with increasing cAMP, coupling between ganglion cells increased with increasing cAMP, and coupling from ganglion to amacrine cells was non-monotonically affected by cAMP. Conclusions: Staining patterns in OFF alpha ganglion cells and their coupled amacrine cells reveal several novel findings: (1) A direct gap junctional pathway exists between OFF alpha ganglion cells, (2) a decrease in frequency of gap junctions across the dendritic field is compensated for by the increase in area to produce an approximately flat profile, (3) members of the more intensely stained amacrine cell type are more strongly coupled to one another than to the ganglion cells, (4) the channels between the ganglion cell and amacrine cells are gated in opposite directions by cAMP. (5) Direct coupling between ganglion cells is primarily decreased by activation of a D2 receptor. (6) Coupling between amacrine cells is decreased by activation of a D1 receptor.
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