OBJECTIVETo investigate the dynamic changes of oxidative stress and nuclear factor-E2 related factor 2 (Nrf2) expression in the lung tissues of acute hydrogen sulfide (H2S) intoxicated rats and intervention effects of ulinastatin (UTI).

METHODSA total of 96 SD rats of clean grade were divided randomly into four groups: normal control group (n = 8), UTI control group (n = 8), H2S -intoxicated model group (n = 40), and UTI treatment group (n = 40). The H2S-intoxicated model group and UTI treatment group were exposed to H2S (283.515 mg/m3) by inhalation for 1h, then UTI treatment group was intraperitoneally exposed to UTI at the dose of 10(5) U/kg for 2 h. H2S-intoxicated model group and UTI treatment group were sacrificed at 2, 6, 12, 24 and 48 h after exposure, respectively. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione (GSH) in the rat lung tissues were measured. The expression levels of Nrf2 mRNA in the rat lung tissues were detected. Pathological changes of rat lung tissues were observed under a light microscope and the lung injury scores were evaluated.

RESULTSCompared with control group, the pulmonary SOD, CAT and GSH levels at 2,6 and 12 h after exposure and the pulmonary GSH-Px levels at 2, 6, 12 and 24 h after exposure in H2S-intoxicated model group significantly decreased (P < 0.05 or P < 0.01). The levels of pulmonary MDA at 2, 6, 12 and 24 h after exposure in H2S-intoxicated model group were significantly higher than those in normal control group (P < 0.01). As compared with H2S -intoxicated model group, the pulmonary GSH-Px activities at 6 and 12 h after exposure, the pulmonary CAT activities at 2, 6 and 12 h after exposure, the pulmonary GSH levels at 2, 6, 12 and 24 h after exposure and the pulmonary SOD activities at 2, 6, 12, 24 and 48 h after exposure in UTI treatment group significantly increased (P < 0.05 or P < 0.01), the pulmonary MDA levels at 2, 6 and 12 h after exposure in UTI treatment group significantly decreased (P < 0.01). The expression levels of Nrf2 mRNA at 2, 6, 12, 24 h after exposure in H2S-intoxicated model group were 0.314 +/- 0.011, 0.269 +/- 0.010, 0.246 +/- 0.011 and 0.221 +/- 0.018, respectively, which were significantly higher than those (0.149 +/- 0.012) in control group (P < 0.01). As compared with H2S-intoxicated model group, the expression levels (0.383 +/- 0.017, 0.377 +/- 0.014, 0.425 +/- 0.017, 0.407 +/- 0.011 and 0.381 +/- 0.010) of Nrf2 mRNA at 2, 6, 12, 24 and 48 h after exposure in UTI treatment group significantly increased (P < 0.01). The lung injury at 24 h after exposure in H2S-intoxicated model group was higher than that in UTI treatment group. Histopathological examination showed that the scores of lung injury at 12, 24 and 48 h after exposure in UTI treatment group was significantly lower than those in H2S-intoxicated model group (P < 0.01).

CONCLUSIONOxidative stress and Nrf2 activation may be the important factors in rat lung injury induced by H2S-intoxicated, UTI may reduce the rat lung injury and protect the rat lung from damage induced by H2S by inhibiting ROS, improving the imbalance in redox and up-regulating Nrf2 mRNA expression.