Objective      To determine the expression of elastin fiber and its related proteins in newborn mice with bronchopulmonary dysplasia (BPD) induced by hyperoxia and investigate the disorder of elastin expression in the development of BPD.       Methods      C57BL/6 mice at 1 day postnatally were randomly divided into control and BPD group (exposure to hyperoxia). HE staining and immunofluorescence assay were used to the morphological changes of mouse lung

elastic fiber staining for the contents of elastic fibers

and Q-PCR to determine the mRNA expression of tropoelastin and related proteins.       Results      Compared to the control

the mice of BPD group were failure to form secondary crest at 3 d

fewer and larger alveoli at 21 d

secondary crest disappeared and elastic fibers were distributed in bad orders and accumulated in the connective tissue matrix. In BPD group

the mRNA expression of tropoelastin

and fibrillin-1

-2

-4 and -5 were increased in 21 d (P0.05). The expression of Lox at mRNA level was increased at 3 to 21 d after exposure to hyperoxia (P0.01). While

the mRNA expression of neutrophil elastase was significantly increased at 1 to 14 d (P0.05).       Conclusion      The balance of elastin fiber is essential for alveoli development. The disturbed elastin fiber structure plays an important role in the pathologic process of BPD.