Fundamental study for development of a new preventive method of radiation pneumonitis

本研究旨在通过大鼠肺照射的实验系统，揭示螺内酯的抗纤维化作用。雌性Wistar大鼠采用200kVp X射线单次15Gy线局部照射大鼠右全胸。在照射前或照射后，将200 mg螺内酯90天缓释丸植入大鼠左侧背部皮下。照射后13周处死大鼠，取双侧肺，固定于甲醛缓冲液中，进行组织病理学检查。对每只肺的纤维化改变和泡沫状巨噬细胞浸润进行评估。照射前给予螺内酯，受照肺纤维化程度加重。如果螺内酯在照射后延迟给药，纤维化改变不能被螺内酯抑制。螺内酯不同给药时间组间泡沫性巨噬细胞渗出无明显差异。

The purpose of this study was to reveal the anti-fibrotic effect of spironolactone after pulmonary irradiation by an experimental system of rats. Female Wistar rats underwent local irradiation of the right whole thorax with a single dose of 15Gy by 200kVp x-rays. 90-day release pellets of 200mg of spironolactone were implanted in the rat's left back subcutaneously before or after irradiation. 13 weeks after irradiation, rats were sacrificed and bilateral lungs were removed and fixed in buffered formaldehyde for histopathological examinations. Fibrotic changes and foamy macrophage infiltrations were evaluated for each lung. The fibrotic changes of the irradiated lungs were severer when spironolactone was administered before irradiation. If spironolactone administration was delayed after irradiation, fibrotic change was not suppressed by spironolactone. Foamy macrophage infiltrations were not significantly different among the groups of different timings of spironolactone administration.