Rod Photoreceptor Activation Alone Defines the Release of Dopamine in the Retina
36 Pages Posted: 15 Nov 2018 Sneak Peek Status: Under ReviewMore...
Retinal dopamine is released by a specialised subset of amacrine cells in response to light and has a potent influence on how the retina responds to, and encodes, visual information. Here we address the critical question of which retinal photoreceptor is responsible for coordinating the release of this neuromodulator. While all three photoreceptor classes: rods, cones and melanopsin-containing retinal ganglion cells (mRGCs) have been shown to provide electrophysiological inputs to dopaminergic amacrine cells (DACs), we show here that the release of dopamine is defined only by rod photoreceptors. Remarkably, this rod signal coordinates both a suppressive signal at low intensities, and drives dopamine release at very bright light intensities. These data further reveal that dopamine release does not necessarily correlate with electrophysiological activity of dopaminergic amacrine cells and add to a growing body of evidence that rods define aspects of retinal function at very bright light levels.
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