Histological and Immunohistochemical Study on the Effect of Constant Light Exposure on T Lymphocyte Subsets in the Thymus and Lymph Node of Male Albino Rats

Abstract

Background: Today there is a widespread exposure to high levels of light at night. . This causes divergence from the natural environment and leads to significant implications on the circadian rhythm. Constant light exposure inhibits melatonin secretion and increases serum concentration of corticosterone. The immune system is very sensitive to stress. Aim of the Work: to study the effect of chronic exposure to constant light (as a model of stress) on the T lymphocytes populations and distribution in the thymus and lymph node. Material and Methods: animals were divided into two groups (10 rats each). The 1st group considered as control group, was kept on a day light-darkness for 12-12 h. The 2nd group was kept under complete artificial light for a period of 4 weeks. Thymus glands and the cervical lymph nodes of rats were removed and processed for haematoxylin and eosin, and immunohistochemical staining for CD3, CD4 and CD8. Results: lymphocytic depletion was noticed in the thymus and lymph nodes of the constant light exposed group. Also the distribution of CD3 and CD4 positive cells were altered in the lymph node of the same group. Conclusion: Constant light stress causes lymphocytic depletion and alters lymphoid cell subsets distribution both in the thymus and lymph nodes.

Can constant light exposure affect the thyroid gland in prepubertal male albino rats? Histological and ultrastructural study

“…Similar finding was reported by Escribano et al [11] who attributed this to increased lipoperoxide levels and reduced anti-oxidative stress biomarkers. In agreement, Rifaai and Abd El Baky [35] demonstrated that 1-month period of constant light caused structural changes in the rat thymus. These changes might cause autoimmune response.…”