RESUMEN
In the present work, agerelated changes in some body defense functions, namely total and differential leucocytic counts, and neutrophil phagocytic activity as well as the serum TNF-a level, plasma nitrate concentration [which reflects NO level] and plasma malondialdehyde [MDA] level, were studied. The effect of selenium supplementation in modulating these changes was also investigated, seeking for a beneficial tool that can help in maintenance of the well-being of aged individuals. The study comprised 62 albino rats that were allocated into 2 main groups: Group I, consisting of control rats, that were further subdivided according to their ages into three subgroups: adult, old and senescent groups; and Group II, consisting of selenium-treated rats that were, also, subdivided into three subgroups matching tile control subgroups. Selenium- treated rats received daily i.p. injection of sodium selenite, 20 micro g/kg b.w., 6 days/week for 4 weeks. Results encountered revealed significant decrease in the lytic index of neutrophils with insignificant decrease in the phagocytic index, accompanied by significant elevation in serum TNF-a level and plasma MDA level, and significant decrease in plasma nitrate concentration in both the old anti senescent rats. The total and differential leucocytic counts were insignificantly different in all age groups. Selenium administration resulted in significant increase in the phagocytic and lytic activities of neutrophils in the old and senescent groups, together with significant decrease in both serum TNF-a and plasma MDA levels. Plasma nitrate concentration was significantly elevated in the adult, old and senescent groups following selenium supplementation. It was, thus, concluded that aging is associated with reduced phagocytic activity of neutrophils and a proinflammatory state, together with enhanced pro-oxidant activity. Selenium, through its action as an antioxidant and anti-inflammatory agent, as well as its role in promoting nitric oxide release, ameliorated these age-related changes