Background: Lung injury is one of the major concerns for chest cancer patients that undergo radiotherapy.so far, some agents have been examined for mitigation of Radiation-induced lung injury. therefore, the purpose of this study was to examine Spirulina's mitigation effects in comparison to Metformin's.

Materials and Methods: 25 male Wistar rats were randomly assigned to five groups (5 rats in each): for the control group, rats didn't receive any intervention. In group 2, spirulina was administered orally to rats. In group 3, rats were irradiated to the chest region with 15 Gray(Gy) x-radiation. In groups 4 and 5, The rats were irradiated in the same way as group 3. Forty-eight hours after irradiation, treatment with Spirulina and Metformin began. All rats were sacrificed after Eighty day and their lung tissues were removed for histopathological, and biochemical assays.

Results: Radiation exposure resulted infiltration of lymph cells around the bronchioles and blood vessels, thickening of the alveolar wall, and the disruption of the alveolar structure, as well as deposition of collagen fibers. Both spirulina and metformin were effective in preventing morphological alterations, albeit Metformin's effect was stronger than Spirulina's. Moreover, Irradiation was associated with an increase in MDA (Malondialdehyde) levels and suppressed the SOD (superoxide dismutase) and GPx (glutathione peroxidase) activity in lung tissue. Metformin decreased MDA in the lung while spirulina didn't have any effect on it. Also, Metformin and Spirulina both increased the SOD and GPx activity in lung tissue.

Conclusion: Metformin and Spirulina could mitigate radiation-induced injuries in lung. A comparison between these agents showed that metformin may be a more effective mitigator compared to spirulina.

Keywords: Spirulina, Mitigation, Radiation, Oxidative stress, Lung injury, Radiation Pneumonitis

Abbreviations: MDA: Malondialdehyde; SOD: Superoxide Dismutase; GPx: Glutathione Peroxidase