RUI: Pigment Granule Dispersion in Teleost Retinal Pigment Epithelium: Cholinergic Mechanisms

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The proposed research looks at what happens when light hits the eye.Research will examine what happens when the eye adjusts to changing lightlevels and how that information is transmitted between the retina and theretinal pigment epithelium (RPE). It will zero in on tiny chemicalmessengers used by the retina to communicate with the RPE. The RPE is athin layer of tissue located next to the retina.The researchers will use fish eyes as a source of tissue for these studies.Unlike human eyes, fish eyes have pupils of fixed diameter. Fish don'tadjust to changing light by dilating or constricting their pupils the waypeople do. Instead they rearrange their light-sensitive photoreceptors andthe pigment granules in the RPE to get just the right amount of light to thephotoreceptors, rods or cones, best suited for the job. In the light,pigment granules in the RPE spread out into finger-like extensions thatinterlace with the rods and cones. These rearrangements let the RPE shadethe rod photoreceptors, which are specialized for night vision, while stillpermitting the cone photoreceptors, bright light and color visionspecialists, to detect light.This study will examine the receptors through which acetylcholine, one ofthe tiny chemical messengers, operates. Receptors are like little antennaefound on the surface of cells, and they detect specific chemicals in theirenvironment. There are many different types of receptors for acetylcholine.Each detects acetylcholine, but each has a different effect on molecularsignals inside the cell. This study will use chemicals that either mimic orblock acetylcholine to figure out what type of receptor is involved inpigment dispersion. This research will illuminate a novel signaling pathwayfor light adaptation, enhancing understanding of how the eye works.