Abstract
Abstract: :
Purpose: Photoelectric dyes absorb light and convert photon energy to electric potentials. To test whether these dyes could be used for retinal prosthesis, a simple in vitro screening system was developed. Methods: Retinal neurons were cultured from the eyes of chick embryos at the 10-day embryonic stage at which no retinal photoreceptor cells yet developed. Intracellular calcium elevation was observed with Fluo-4 in cultured retinal neurons before and after a photoelectric dye was applied at the varying concentration to the culture medium. Seven photoelectric dyes (NK-2045, NK-5962, NK-5078, NK-3630, NK-3041, NK-2761, NK-1952, Hayashibara Biochemical Laboratories, Inc., Okayama City, Japan) were tested in this study (see the structure of the dyes at http://hayashibara.co.jp). Results: Five (NK-5962, NK-3630, NK-3041, NK-2761, NK-1952) of 7 photoelectric dyes tested in this in vitro system induced intracellular calcium elevation in cultured chick retinal neurons. The minimum concentration of the dyes to generate the response ranged from 0.0005 to 0.5 microgram/ml. The intracellular calcium elevation generated by the 5 photoelectric dyes was blocked by extracellular calcium depletion. The response was also inhibited by the presence of voltage-gated calcium channel blockers except for one dye (NK-1952). Conclusions: The photoelectric dyes absorbed light under an inverted microscope and stimulated retinal neurons. This simple in vitro system allowed to screen photoelectric dyes which could be used for retinal prosthesis.
Keywords: retinal culture • pharmacology • calcium