Effects Of Dexamethasone On Airway And Pulmonary Surfactant Of Asthma Guinea-pigs

OBJECTIVE:(1)To observe the pathologic changes of bronchus and lung tissue in guinea pig asthma models;(2)To observe the pathologic changes of bronchus and lung tissue in guinea pig asthma models which were interfered in dexamethasone.(3)To investigate the effects of dexamethasone on pulmonary surfactant (PS) component and ultrastructure of asthma guinea-pigs.METHODS: (1)24 guinea-pigs were randomly allocated to three groups on average: The guinea-pigs asthma models (asthma group)were established by sensitization and challenge with ovalbumin (OVA); One part of sensitized guinea-pigs were interfered in dexamethasone (dexamethasone group) before they were challenged for the second time; the normal guinea-pigs (control group)were treated with normal saline instead of OVA . The pathologic changes of bronchus and lung tissue in guinea pigs were observed by microscope respectively. (2)PS was extracted from bronchial alveolar lavage fluid(BALF) using chloroform/methanol and the amount of phosphatidylcholine and phosphatidylethanolamine were determined by the method of high performance liquid chromatograpy(HPLC). (3) Total protein (TP) of BALF were measured with Lowry method. (4)We adopted the method of transmission electron microscope histochemistry to observe the ultrastructure change of PS in guinea pigs of various groups .RESULTS: (1) Significant inflammation with infiltration of eosinophils,lymphocytes in the bronchus and lung tissue was observed in guinea pig asthma models.The thickness of bronchial wall in asthmatic group were obviously increased. These pathologic changes in asthmatic group were relieved by dexamethasone. (2) PC and PE increased while TP decreased in BALF in dexamethasone group compared with asthmatic group.(3)The lamellae bodies in type II pneumonocytes were vacuolated in asthma group; the lamellae bodies in type II pneumonocytes were slightly vacuolated in the dexamethasone group .CONCLUSION: (1)The whole airway and lung system in guinea pig asthma models present significant inflammation with infiltration of eosinophils, the inflammatory change in asthmatic group were relieved by dexamethasone.(2)There was an inactivation or dysfunction of PS in guinea pig with asthma ,and dexamethasone could accelerate PS synthesis and improve its function .In a word,the effect of dexamethasone on PS is one of mechanisms that dexamethasone cure asthma effectively.