Résumé
BACKGROUND:This study was undertaken to observe the concentration of SP-A/B and the pulmonary surfactant in the lung tissue of rats with acute lung injury/acute respiratory distress syndrome caused by paraquat poisoning after the treatment of metabolic antioxidant-lipoic acid and whether its influence was related to TNF-α. METHODS:Sixty-six male Sprage-Dawley rats were randomly divided into three groups:normal control group (NS group), 6 rats; paraquat poisoning group (PQ group), 30 rats; and paraquat+lipoic acid treatment group (LA group), 30 rats. The rats in the PQ and LA groups were subdivided into 3-, 6-, 12-, 24-, 48-hour subgroups, with 6 rats in each group. After the rats were sacrificed, lung tissue from the same part was taken from the rats. After HE staining, histological changes were observed in the tissue under a light microscope. Lung tissue was also taken to test the levels of superoxide dismutase (SOD) and malondialdehyde (MDA). Whole blood (0.8 mL) without anticoagulant was drawn from the tail vein of rats for the determination of the TNF-α level. The total RNA of the lung tissue was collected, and the Rt-PCR method was used to measure the levels of SP-A and SP-B mRNA. RESULTS:HE staining showed that histopathological changes were milder in the LA group than in the PQ group. There were significant differences in MDA and SOD levels between different intervals both in intergroups and intragroups except the 3-hour subgroup (P<0.01). Likewise, the significant differences in the levels of TNF-α were also present between the three groups and between different intervals (P<0.01). The significant differences in SP-A mRNA and SP-B mRNA amplification ratio were seen between the three groups at the same intervals (P<0.01), but the differences between different intervals in the PQ group were statistically significant (P<0.05). The differences between different intervals in the LA group were statistically significant (P<0.01). CONCLUSION:Lipoic acid in acute paraquat poisoning could diminish lung tissue damage by regulating directly tumor necrosis factor and indirectly the content of pulmonary surfactant so as to reduce pulmonary edema, improve lung compliance, and finally protect lung tissues.
Résumé
Objective To observe the changes in concentrations of pulmonary surfactant SP-A/B in lung tissue during acute lung injury (ALI) /acute respiratory distress syndrome (ARDS) induced by acute paraquat poisoning (PQP) after the treatment with metabolic antioxidant,lipoic acid,and to explore the potential involvement of TNF-α in ALI/ARDS as well as to discuss the assumed protective mechanisms of lipoic acid against acute lung injury.Methods Sixty-six male Sprage-Dawley rats were randomly (random number) divided into 3 groups,namely control group (NS,n =6),paraquat poisoning group (PQ,n =30),paraquat + lipoic acid treatment group (LA,n =30).Then both group PQ and group LA were further divided separately into five subgroups,namely 3,6,12,24 and 48 h subgroups (n =6 in each subgroup).After rats sacrificed,the lung tissues were selected,and after HE staining,histological changes were observed under light microscope.Histopathological changes were inflammation and fibrosis in models successfully established.The lung tissues were also taken for tests of SOD and MDA levels.Specimens of whole blood 0.8 mL without anticoagulant were taken from tail vein of rats for determining the TNF-α level.The expressions of SP-A mRNA and SP-B mRNA were measured with RT-PCR from total RNA of the lung tissue.Results ① HE staining showed that the histopathological changes were milder in LA group than that in PQ group.② There were significant differences in MDA and SOD levels between different intervals both in intergroups and intragroup except the groups of 3 hours (P ＜ 0.01).③ Likewise,the significant differences in the levels of TNF-α were also present between three groups and between different intervals (P＜0.01).④ The significant differences in SP-A mRNA and SP-B mRNA amplification ratio existed between three groups at the same interval (P ＜ 0.01),but those differences between different intervals in group PQ were of statistical significance (P ＜ 0.05).And those differences between diffirent intervals in group LA were statistically significant (P ＜0.01).Conclusions Lipoic acid in acute paraquat poisoning could lessen lung tissue damage,which might be directly dominated by the levels of tumor necrosis factor,and in turn indirectly affect the content of pulmonary surfactant,thereby reducing pulmonary edema and improving lung compliance,then protecting the lung tissues.
Résumé
Superoxide dismutase was prepared from human crythrocytes. The sample was purified using a DEAE-cellulose column and chromatography on Sephadex G-75. During purification the produce determined the protein peak and SOD active peak at the same time to decide the SOD was present. The enzyme exhibited an ultraviolet absorption spectra with a maximum at 270-275 nm. Polyacrylamide disc gel electrophoresis revealed three bands which were in dose agreement with the active bands by reduction of NBT. The molecular weight was 41687, 31623 and 15136. The specific activity of human SOD possessed 3300 units per mg It contained 2 eq of Cu, Zn per mole of enzyme, respectively.