To explore the variation of interleukin(IL)-8 and tumor necrosis factor(TNF)-α contents in pulmonary alveoli of neonatal SD rats with hyperoxia exposed.

A total of 100 Sprague-Dawley(SD) rats which were healthy and 24 h after birth, were chosen as study objects. They were randomly divided into hyperxia group and air group, and 50 rats in each. Neonatal SD rats in hyperxia group were exposed to the oxygen concentration over or equal to 95%, while neonatal SD rats in air group were raised normally in air. Ten neonatal SD rats in each group were sacrificed at the 1st, 3rd, 6th, 10th and 14th day after oxygen expose, and underwent alveolar wash. The contents of IL-8 and TNF-α in the bronchoalveolar lavage fluid were detected by double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). The differences of IL-8 and TNF-α contents in the bronchoalveolar lavage fluid between two groups of neonatal SD rats, and the differences of IL-8 and TNF-α contents among different time points above mentioned in hyperxia group were statistically compared.There were no significant differences between two groups of neonatal SD rats in gender constituent ratio and birth weight (P>0.05). The disposition of the animals in experimental process was in accordance with the ethical standard of animals.

①Neonatal SD rats in hyperxia group had some bad performances on 14th day of hyperoxia expose, such as growth retardation, sluggishness, weight gain stopped, rapid and shallow breathing and cyanosis of oral lips, etc.. ②The contents of IL-8 in the bronchoalveolar lavage fluid of neonatal SD rats on 3rd, 6th, 10th, 14th days in hyperxia group were higher than those of air group[(262.4±12.5)×10^-15 g/L vs (94.0±12.5)×10^-15 g/L, (374.1±14.8)×10^-15 g/L vs (94.8±7.2)×10^-15 g/L, (345.7±17.5)×10^-15 g/L vs (94.5±4.3)×10^-15 g/L, (295.5±26.6)×10^-15 g/L vs (95.6±7.5)×10^-15 g/L], and the differences were statistically significant(t=36.909, 58.033, 43.981, 22.878; P<0.05). The contents of TNF-α in the bronchoalveolar lavage fluid of neonatal SD rats on 1st, 3rd, 6th, 10th, 14th days in hyperxia group were higher than those of air group[(43.0±4.5)×10^-15 g/L vs (29.9±1.7)×10^-15 g/L, (59.3±7.0)×10^-15 g/L vs (33.3±4.1)×10^-15 g/L, (55.1±7.7)×10^-15 g/L vs (31.1±2.5)×10^-15 g/L, (43.2±5.1)×10^-15 g/L vs (31.2±3.4)×10^-15 g/L, (34.4±3.8)×10^-15 g/L vs (30.7±2.8)×10^-15 g/L], and the differences were statistically significant(t=-6.287, -10.190, -7.358, -2.508, -4.516; P<0.05). ③The IL-8 content in bronchoalveolar lavage fluid of neonatal SD rats on 6th day in hyperxia group was higher than that of 1st, 3rd, 10th, 14th day, respectively(t=-50.812, -18.265, -3.910, -8.170; P<0.05), that of 10th day was higher than that of 14th day(t=-4.987, P<0.05), and all the differences above were statistically significant. The TNF-α content in bronchoalveolar lavage fluid of neonatal SD rats on 3rd day in hyperxia group was higher than that of 1st, 6th, 10th, 14th day, respectively(t=-6.209, -3.719, -5.900, -9.974; P<0.05), those of 6th and 10th days were both higher than that of 14th day(t=-4.416, 4.732; P<0.05), and all the differences above were statistically significant.

The IL-8 and TNF-α may participate in the prophase inflammatory reaction when hyperoxia-induced lung injury occurred in neonatal SD rats.