OBJECTIVETo observe the effect of intra-amniotic administration of pulmonary surfactant (PS) on the lung ultrastructure and expression of surfactant protein A (SP-A) in fetal rabbit with intrauterine infection.

METHODSIntra-amniotic PS injection was administered in a rabbit model of premature rupture of membrane and intrauterine infection induced by intrauterine colibacillus injection on the gestational days 24 and 26 days. The lung ultrastructural changes in the fetal rabbits were observed using electron microscope, and the expression of SP-A was measured with immunohistochemical staining and Western blotting 19.5 h after the PS administration.

RESULTSalveolar type I cell (AT I), alveolar type II cell (AT II). In fetal rabbits with intrauterine colibacillus injection, inflammatory cell infiltration was observed in the pulmonary alveolus, bronchus lumens and intracytoplasm irrespective of PS administration. Compared with those in normal fetal rabbits, the number of alveolar type II cells (AT II) in the lung tissue decreased in fetal rabbits with intrauterine infection, and vacuolization of the lamellar bodies occurred with evidence of cell apoptosis; PS administration resulted in increased number of the AT II cells and lamellar bodies and reduced the cell apoptosis. The expression of SP-A was significantly lower in the infection group than in normal control group (P<0.05), but comparable between the PS group and the control group (P>0.05).

CONCLUSIONChanges in pulmonary alveolar ultrastructure and decreased expression of SP-A occur in fetal rabbits after intrauterine infection, and intra-amniotic administration of PS can alleviate these changes to promote lung maturation.