Objective: To investigate the protective effect of irisquinone for radiation-inducedlung injury (RILI) in SD rats. Method: Two hundred and ten SD rats were randomly divided into 0.9% sodium chloride solution group (normal group)

irisquinone group (single drug group)

radiation group (model group)

hormone group

high-dose (60 mg · kg-1 · d-1)

medium-dose (30 mg · kg-1 · d-1)

and low-dose (15 mg · kg-1 · d-1) irisquinone+radiation group

n=30 in each group. The models of RILI in SD rats were established by irradiating right whole chest with a single dose of 20 Gy using 60Co γ therapeutic machine. Rats were sacrificed from the seven groups at week 1

4

8

12 and 24 post-irradiation

and the pathological changes of the lung were observed by hematoxylin-eosin(HE) staining and Masson staining; content of hydroxyproline in lung tissues was detected by UV spectrophotometer

tumor necrosis factor-α(TNF-α)

interleukin-1β(IL-1β) and transforming growth factor β1(TGF-β1) in serum were detected by enzyme-linked immunosorbent assay

expression of TNF-α and TGF-β1 in lung tissues were detected by immunohistochemical method. Result: High-dose and medium-dose irisquinone+radiation group could significantly ameliorate radiation-inducedlung injury

effectively reduce the content of hydroxyproline and inhibite the expression of TNF-α

IL-1β and TGF-β1

with statistically significant difference compared with model group (P<0.05). There was no significant difference between the low-dose irisquinone+radiation group and the model group. There was no statistically significant difference between the single drug group and the normal group. Conclusion: The high-dose and medium-dose irisquinone has protective effect on the radiation-induced lung injury and is nearly non-toxic for the lung tissues of rats.