EFFECT OF ALUMINUM, CADMIUM AND LEAD ON RAT LUNG: PROTECTIVE ROLE OF SELENIUM.

Adult male and female albino rats were treated orally with either sublethal doses of aluminum chloride, cadmium chloride or lead acetate alone or in combination with sublethal dose of sodium selenite. The rats were treated on alternate day for eight weeks and divided into eight groups of 5 rats each: control, (aluminum chloride 30 mg/kg bw, cadmium chloride 10 mg/kg bw and lead acetate 25 mg/kg bw) alone or in-combination with 0.4 mg/kg bw sodium selenite for each group. All animals were decapitated and lung tissues were dissected out, from each animal. Tissue samples were processed for light microscopical examination. Results showed that treatment with metals alone reduced rat body weight gain, and few rats died. There were many histopathological changes in the lung tissue of rats treated with metals alone such as, general impairment of the normal architectural organization of lung lobes and shredding of the bronchiolar epithelium cell with debris within its lumen and thickening of the interalveolar septa due to the inflammatory cells infiltrated of the alveolar walls. In some examined sections interalveolar septa ruptured forming large alveolar sacs as well as, hemorrhage and thick walled congested blood vessels. Many extrinsic allergic aveolitis were also seen in different areas of the pulmonary tissue. In some slides a lung abscess was seen and represented with a necrotic area and many pus cells. Administration of selenium concurrently with these metals ameliorated all the above adverse effects. In conclusion, Se has beneficial effects and could be able to antagonize Al, Cd and Pb toxicity on lung; effects that might be attributed to its antioxidant activity leading to scavenging free radicals.