Effect of Aging on the Structure of Thoracic Aorta of Male Albino Rat and the Possible Role of vitamin E

Abstract

Background: Life expectancy has increased recently throughout the world leading to a growing interest in the so-called age-associated diseases affecting multiple body systems. One of the most frequently affected systems is the cardiovascular system where aging alters its histological structure thus making it more vulnerable to pathology even in absence of traditional risk factors as hypertension, diabetes, or smoking. Some studies suggested that vitamin E may be an important factor in preventing the development and progression of atherosclerosis. However, there is still no complete consensus about its age related cardioprotective effects. Aim of the Work:To study the age related histological changes in the thoracic aorta of male albino rats, and the possible effect of vitamin E. Materials and Methods: Thirty male albino rats were used in this study, 10 adults, aging from 3 to 6 months and weighing 180-220 gms, and 20 senile, aging from 18 to 24 months and weighing 280-300 gms. Group I (Control adult Group): composed of ten adult rats and was further subdivided into: Subgroup IA: containing five rats that were not subjected to any procedure. Subgroup IB: containing five rats that were given sesame oil (the solvent used for vitamin E) 3.6 ml daily for 6 weeks. Group II (control senile Group): composed of ten senile rats and was further subdivided into Subgroup IIA: consisted of five rats that were not subjected to any procedure. Subgroup IIB: consisted of five rats that were given sesame oil 3.6 ml daily for 6 weeks. Group III (senile Vitamin E Group): composed of ten senile rats that were given 300mg vitamin E dissolved in 3.6 ml sesame oil daily for 6 weeks. Results: Histological examination of the thoracic aorta of senile rats showed areas of intimal thickening and others of hypertrophy with loss of linear arrangement of endothelial nuclei and accumulation of dark brownish granules. Tunica media showed areas of degeneration, fragmentation of elastic fibers and marked increase in collagen bundles on expense of SMCs. Localized outpouching of the vessel wall was also encountered. Connective tissue of tunica adventitia was sparse, thin and widely separated. Immunohistochemically stained sections revealed multiple areas of weak immune reactivity interrupting the arrangement of the SMCs. On the other hand, thoracic aorta of vitamin E treated rat revealed relatively regular tunica intima with mostly flattened endothelial cells apart from few irregular ones. Elastic fibers and collagen bundles in tunica media revealed obvious improvement and appeared almost regular apart from few vacuolation seen among collagen bundles. Tunica adventitia consisted of wavy, dense connective tissue with some areas of separation. Immunohistochemically stained sections showed highly actin immune positive SMCs with very scanty areas of interruption. Conclusion: Vitamin E supplementation to senile rats obviously improved their vessel wall histology. Therefore, vitamin E supplementation is strongly advised to the senile for better vascular str...