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Abstract

Manganese superoxide dismutase (Mn-SOD) is a naturally-occurring scavenger of superoxide, one of several reactive oxygen intermediates. To determine if Mn-SOD expression is enhanced as a defensive mechanism against oxidative challenges, such as intense light exposure, rats were exposed to cyclic light (80 lux) for 2 weeks, intense light (1,800 lux) for 24 h, and then again to cyclic light. Experimental and control (exposed to cyclic light only) eyes were enucleated 3 h, 1, 3, 7, and 14 days after light challenge. Protein expression was examined immunohistochemically using rabbit antisera against rat Mn-SOD. There was no significant difference between the light-exposed and the control groups in the thickness of the outer nuclear layers. Both retinal pigment epithelial cells and photoreceptor inner segments in the normal retina were labeled for Mn-SOD. Mn-SOD labeling was lost 3 h and day 1 after light challenge. It was re-expressed in the retinal pigment epithelial cells 3, 7, and 14 days after the light challenge, and in the photoreceptor inner segments after day 14. These results suggest that the retina might have a protective potential against light damage, in which Mn-SOD may play an important role.

Suppression of Light-Induced Retinal Degeneration by Quercetin via the AP-1 Pathway in Rats

“…The light exposure experiment was performed based on the methods of Yamamoto and associates with minor modification [28]. Briefly, 8-week-old Sprague-Dawley rats were exposed to white fluorescent light; the average light intensity at 10 randomly selected points in the cages was 3000 lux for 24 h. All experiments began at 9 a.m. because the ROS phagocytosis process by RPE cells is controlled by circadian rhythm, and this activity peaks 2 h after the start of the light cycle [29,30].…”