Morphological study of retinal neurons after continuous exposure to fluorescent light in adult male albino rats

Abstract

Retinal function depends on light trapping. However, continuous exposure to light may cause damage to the highly vulnerable retinal structure. Aim of the study This study aimed to investigate the possible histological alterations that might occur in the retinal neurons as a result of continuous exposure to fluorescent light in adult male albino rats. Materials and methods Ten healthy adult male albino rats were equally divided into two groups: a control group and a light-exposed group. Rats of control group were kept in 12 h light/12 h dark for 12 weeks. Rats of light-exposed group were put in top-opened cages illuminated by white fluorescent bulbs continuously for 1 week and then were kept in 12 h light/12 h dark for the following 11 weeks. The retina was extirpated and processed for examination by light and electron microscopy. The thickness of outer nuclear, inner nuclear, outer plexiform, and inner plexiform layers was estimated morphometrically and was statistically analyzed. ResultsFluorescent light-exposed neural retina revealed that photoreceptor outer segments were markedly disorganized and inner segments were short and less condensed. Outer nuclear layer contained few photoreceptors with marked intercellular spaces. Inner nuclear layer showed wide spaces between its neurons, with some of them having shrunken nuclei and others having disintegrated nuclei. Mü ller cells with deeply stained bodies and processes were seen in inner and outer nuclear layers. Many ectopic neurons were detected in the inner plexiform layer. Ganglion cell layer mostly contained deeply stained glial cells and few ganglion neurons. Nerve fiber layer showed an apparent increase in thickness. The estimated and analyzed thickness of the outer nuclear, inner nuclear, outer plexiform, and inner plexiform layers confirmed the results. ConclusionContinuous exposure to fluorescent light triggered retinal remodeling, including neuronal loss, reactive gliosis with neuronal and glial cells migration. This may lead to visual impairment.

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

“…Group II of the current study revealed decrease in the number of ganglion cells in the ganglion cell layer (GCL) supported by the significant decrease in its mean number versus control group and the appearance of shrunken and irregular nuclei. This is consistent with what was reported in a previous study after exposure to fluorescent light [26] . Such finding could be explained by apoptotic ganglion cell death based on the presence of caspase-3 positive immunoreactivity in few cells of GCL.…”

“…Other essential finding reported in this study after white PC LED light exposure was the presence of multiple deeply stained glial cells within the GCL which was similarly reported previously [26] . This finding could be explained by that glial cells reacted to neuronal lesion by reactive gliosis (cellular hypertrophy with increased production of intermediate filaments and cellular hyperplasia) to support the injured neurons through production of neurotrophic factors.…”

“…This occurred through post synaptic cellular death where there was synaptic loss with subsequent loss of the trophic factors and neurotransmitters [23] . Death of INL' cells was also reported in a previous study after exposure of the rats to white light [14,26] . Accordingly, death of some cells of both ONL and INL could furtherly explain disruption of the outer plexiform layer (OPL) recorded in group II of the present study.…”