Leptin Promotes Fetal Lung Maturity and Upregulates SP-A Expression in Pulmonary Alveoli Type-II Epithelial Cells Involving TTF-1 Activation
Figure 5
Effect of leptin on the expression of TTF-1 in fetal lungs and type-II AECs.
A: Cultured type-II AECs were treated as above, and whole lysates were detected by immunoblotting with TTF-1 antibody. *P<0.01; a: vs the hypoxia-treated group, b: vs the 1600 ng/mL leptin-treated group (n = 3). B: Type-II AECs were exposed to hypoxia for 12 h and treated with 1600 ng/ml leptin for the indicated times. Protein levels were analyzed by immunoblotting. #P<0.05 vs the corresponding untreated cells (n = 3). C: Lung tissues from fetal rats at 21 days’ gestation were fixed and incubated with a monoclonal antibody against TTF-1, and visualized by diaminobenzidine color reaction (×200). TTF-1 was mainly expressed in the nuclei of AECs, and leptin markedly upregulated the expression of TTF-1 in the lungs of FGR fetuses. D: Immunofluorescent analysis with antibodies against TTF-1 (green) and SP-C (red) showed that TTF-1 mainly expressed in the type-II AECs and increased in fetal lungs of FGR rats with leptin treatment. Nuclei were stained with DAPI (blue) (×320).