Tissue histology and antioxidant defense system in female rats exposed to sun rays

Abstract

Although considerable distance separates the earth and the sun- the star at the center of the Solar System- yet its harmful effects after excessive exposure to ultraviolet rays of the sun have been identified as a cause of many pathological conditions. The role of lipid peroxidation in various disease states has also been highlighted. The aim of the study is to investigate whether 4 hourly exposure to sunlight is capable of inducing tissue damage that is oxidative stress-mediated. Fourteen female Wistar rats of 13 weeks of age were distributed into 2 groups. Sun-exposed rats were left in an open place without any form of sun-screen for protection against sunlight. Blood was collected from the animals by retro-orbital bleeding. The serum obtained was used for the estimation of activities of catalase, superoxide dismutase, glutathione S transferase, glutathione reductase and glutathione peroxidase, as well as levels of malondialdehyde (MDA), and reduced and oxidized glutathione. Sections of the brain, lung, heart, and ileum were processed and stained with haematoxylin and eosin (H&E). Statistical analysis was carried out using the Student’s t test. P ≤ 0 .05 was considered significant. Results showed that there were significant increases in serum levels of MDA and GSSG as well as significant decreases for GSH, Gln-px and SOD, an indication of the involvement of oxidative stress in histologic changes recorded for some of these tissues. Histologic changes like mild congestion of the coronary vessel (heart) as well as mild pulmonary congestion (lung). The absence of histolgic changes in tissues like kidney and liver even when some of the oxidative stress markers were significantly different and suggestive of free radical generation, may be as a result of the fact that free- radical are highly reactive with very short half-lives, which means they combine almost immediately after their production in situ.