It can be concluded that the short period of constant light for one month had more or less no apparent effect on thyroid gland tissues while longer light periods for three months brought on detrimental outcomes on the thyroid gland structure of male albino rats.
Introduction
Age related degeneration (ARD) is the leading cause of irreversible blindness among old people. Epidemiologic studies have suggested that nutritional parameters such as dietary fat and cholesterol may play a role in the pathogenesis of retinal degeneration. High intake of saturated fat and cholesterol is correlated with a higher risk for early ARD which occurs either directly or through the promotion of vascular pathology.
Aim of the work
was to evaluate the early histological and immunohistochemical changes of the retina, induced by hypercholesterolemia in adult male albino rat and comparing these changes with similar results in aged male albino rat and to apply a comparative lipid profile biochemical study between the different groups.
Materials and methods
Forty male albino Sprague Dawley rats were used in the study. They were divided into four groups, ten rats per each; Group I: control adult: aged 3-6 months and group II: control aged: aged 24 months were fed on standard diet, Group III: adult hypercholesterolemic group and group IV: aged hypercholesterolemic group were fed on hypercholesterolemic diet which consisted of the same ingredients of the standard diet except for the cellulose was reduced to (4%) with addition of cholesterol (1%) for duration of 6 weeks. At the end, retinal specimens were collected and processed for light microscopic and immunohistochemical examination.
Results
The aged rats showed marked disruption of the normal histological architecture of retina and affection of each individual retinal layer. Hypercholesterolemia markedly affected the adult rat retina and aggravated the aged retina. The affected retinae showed marked thinning of the retinal thickness, disorganization of the cell within the neuronal cell layer with decreased number of the cells within ganglion-cell layer. Immunohistochemistry revealed significant increase in retinal reactivity to glial fibrillary acidic protein, vascular endothelial growth factor, caspase 3 and nitric oxide synthase by aging and hyperlipidaemia.
Conclusion
The present work suggested that hypercholesterolemia is an important risk factor that can accelerates aging of healthy adult retina producing age related retinal degeneration.
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