Short-term changes in histopathological markers of irradiated rat's lung: Preliminary study

To investigate early radiation-induced lung injury in cells of the rat's lung following whole thoracic radiation. Wistar rats were used in the experiments (weighing 170-210g). The animals were divided into 6 groups. One group received no radiation. Other groups were exposed to 9, 11, 13, 15, 17 Gy in a single dose of ⁶⁰Co gamma rays, respectively. The animals were sacrificed at 6 weeks after irradiation. The lungs were dissected and blinded histopathological evaluation was performed. When the lungs were removed at 6 weeks after whole thoracic irradiation, a mild level of inflammation, exudate, mononuclear cell infiltration, plasma cell, and thickened bronchial wall were observed in the lung cells to 9-11 Gy radiation groups. A small increase in histological damage of the previously described section plus hyperemia, thinned alveolar wall, and dilated alveolar space were seen in the irradiated rats to 13 Gy. In addition to the changes described in the last group, hemorrhage, necrosis occurred in the irradiated animals to 15-17 Gy. This study puts forward the histopathological evidence of radiation-induced acute lung injury to be evaluated further for lung protection during radiation therapy of thoracic cage. More investigation is needed to better clarify different aspects of radiation-induced lung injury. The specification of dose-dependent pathologic changes in our model will facilitate future investigations about the molecular mechanisms of radiation-induced lung injury using genetically modified Wistar rats.