Histological study on the detrimental influences of white LED light on the retina of adult albino rat and the potential effect of simultaneous nicotine administration with highlighting their possible mechanisms

Abstract

Background: Light-emitting diodes (LED), the most effective and economic artificial source of light, proved to emit more blue light than traditional sources even the most popular white LED light. Blue light had many health problems as light-retinal damage. Nicotine, one of the main solid of cigarette smoke, caused end organ damage and promoted retinal lesions through different mechanisms.Aim of the work: Investigating the possible retinal changes induced by domestic white LED light in albino rat and the probable impact of nicotine on these changes with highlighting their possible mechanisms.Materials and Methods: Forty-two adult male albino rats were equally divided into three groups; control (I), LED (II) & Nicotine-LED (III). Groups II and III were kept in 5 days normal light/dark cycle, 14 days darkness then normal cycle with domestic white LED light for 9 days. Additionally, rats of group III received daily oral nicotine (3 mg /day) for 28 days (experimental duration). All rats were sacrificed at the end of the experiment and superoxide anion (O2−) level was measured in the retinal homogenates of each group. Retinal sections from all groups were subjected to toluidine blue, H&E and immunohistochemical stains for caspase-3, vimentin and inducible nitric oxide synthase (iNOS). Area percent of positive reactions, thickness of outer and inner nuclear layers and number of ganglion cells were measured. The obtained data is then statistically analyzed.Results: Features of retinal damage and increased O2− level were detected in both groups II and III with marked injury in group III. Studying group III immunohistochemically, revealed marked increase in vimentin and iNOS and significant decrease in caspase-3 positive reactions versus group II.Conclusions: White LED light could result into deleterious retinal damage which could be exaggerated by nicotine, a main component of cigarette smoke, and rapidly progressed to age related macular degeneration.