ABSTRACT
<p><b>BACKGROUND</b>Retinal light injury can lead to degeneration of the photoreceptor cell layer. It has been hypothesized that the mechanism for this process is the photochemical damage. Ginkgo balboa extract (Ginkgo biloba extract EGB761) EGB761 is a free radical scavenger. The purpose of this study was to investigate the possible effect of orally administered EGB761 on retinal light damage of mouse photoreceptor cells.</p><p><b>METHODS</b>Kunming mice were randomly chosen for the following groups containing 20 animals in each: control group, light damage group, saline control group, and drug treatment group. The drug treatment group and saline control group were given daily gavage of EGB761 (150 mg×kg(-1)×d(-1)) one week before light exposure. At 7, 14, and 30 days after light exposure, animals were sacrificed and eyes were examined by light microscopy, electron microscopy, and retinal histopathology using in situ detection of apoptotic cells.</p><p><b>RESULTS</b>In the light damage group after 7 days there was visible edema, and the outer nuclear layer appeared withered with deeply stained dead cells, leaving only a thin nuclear layer of 7 - 8 cells. After 14 days, the photoreceptor cell layer disappeared, leaving only the outer nuclear layer of 1 - 3 cells with an average thickness of (37.988 ± 1.207) µm. The average thickness of the retina was (126.32 ± 2.31) µm. In the drug treatment group, the photoreceptor cell layer and outer nuclear layer damage were significantly lower than the saline group (t = 21.993, P < 0.001), demonstrating that EGB761, especially at 14 days after light exposure, can reduce retinal light damage in mice.</p><p><b>CONCLUSION</b>Oral administration of EGB761 can partially inhibit apoptosis of photoreceptor cells, resulting in increased photoreceptor cell survival.</p>