Effects of Radon-222 Exposure on Lung Oxidative Stress and Superoxide Dismutase in Male Albino Rats: Roles of Melatonin as an Antioxidant.

This study examines the impacts of radon exposure on male albino rats' lungs, which is a prominent cause of lung cancer, as well as the defensive roles of melatonin as an antioxidant by examining the activities of superoxide dismutase SOD, malondialdehyde MDA, and hydroxyproline. The study is comprised of two experiments. In the first experiment, in a newly built chamber, rats were exposed to radon from (5Ci) of 226Ra source. Rats were divided into seven groups of eight rats. Unlike the control group, the other six groups were exposed to radon, which was assessed using RAD-7 detector, specifically for 30 minutes (D1), 1 hour (D2), 2 hours (D3), 3 hours (D4), 6 hours (D5), and 9 hours (D6). The concentrations were measured to be (6000.014, 12100.028, 24210.057, 36000.086, 72600.172, and 108750.259) Bq.m-3, respectively. The second experiment examined the protective effects of melatonin against radon exposure. The rats were given a low (60 mg/kg diet) and a high (120 mg/kg diet) dose of melatonin and then exposed to radon for six hours. Radon exposure did not significantly alter SOD activity. However, the first and third radon doses lowered SOD activity modestly. After exposure, hydroxyproline levels increased significantly compared to the control group. A statistical result found that radon exposure elevated lung MDA. Melatonin enhanced SOD reductions after radon exposure. However, both MEL doses lowered MDA below the positive control. In conclusion, radon inhalation induces lipid peroxidation. Melatonin reduces MDA and increases SOD activity, making it a good antioxidant against radon exposure.