Cytochrome oxidase activity in rat retina after exposure to 404 nm blue light*

Abstract

Cytochrome oxidase (CYO), a key enzyme in the respiratory chain, was observed as an indicator of retinal metabolism after an in vivo blue light exposure. Thirty Sprague-Dawley rats were exposed to optic radiation of 404 nm with a retinal dose of 110kJ/m2. Immediately after exposure, the CYO activity in the pigment epithelium, in the outer and inner segments of photoreceptors, and in the outer plexiform layer of the exposed retina, was reduced to one-third-to-half of the control level. However, there was an increase in CYO activity in the exposed retina one day after exposure. One week after exposure, the CYO activity in the inner segment and the outer plexiform layer was higher, while the activity in the other two layers was lower, than that at one day, although still higher than in the control. Two weeks after exposure, the CYO activity in the four retinal layers returned to the level of the control retina, as did the activity four weeks after. After exposure, no ophthalmoscopically visible retinal change and no light-microscopically evident morphological alterations were found. There was no retinal edema or loss of photoreceptor cells. The observed alteration in CYO activity after blue light exposure may represent an inhibition of retinal metabolism. The inhibition was reversible. If this compensation mechanism is overwhelmed, retinal damage may occur.

Blue light-induced apoptosis in cultured retinal pigment epithelium cells of the rat

“…Different explanations have been given for blue light toxicity: (1) damage to blue-sensitive chromophores [3];…”

Observation of ultrastructural changes in cultured retinal pigment epithelium following exposure to blue light

“…Numerous publications have since described the morphological changes in retinal pigment epithelium (RPE) induced by exposure to light [2,10,17,18,22,27,33]. Hansson cited the time course and oxidative enzyme changes in the retina [16,18] as the evidence that the primary site damaged was the RPE and that damage to the photoreceptor was only secondary.…”

Light Effects on Mitochondrial Photosensitizers in Relation to Retinal Degeneration

“…Indeed a variety of studies have suggested that photosynthesizers located to mitochondria generate ROS as a result of interaction with light [44][45][46][47][48][49][50][51]. Good evidence for this being the case was obtained by studies where freshly isolated mitochondria from the rat liver was exposed to light (400-760 nm) as impinging on the retina.…”