Metyrapone blocks maternal food restriction-induced changes in female rat offspring lung development

Maternal food restriction (MFR) during pregnancy affects pulmonary surfactant production in the intrauterine growth-restricted (IUGR) offspring through unknown mechanisms. Since pulmonary surfactant production is regulated by maternal and fetal corticosteroid levels, both known to be increased in IUGR pregnancies, we hypothesized that metyrapone (MTP), a glucocorticoid synthesis inhibitor, would block the effects of MFR on surfactant production in the offspring. Three groups of pregnant rat dams were used (1) control dams fed ad libitum; (2) MFR (50% reduction in calories) from days 10 to 22 of gestation; and (3) MFR + MTP in drinking water (0.5 mg/mL), days 11 to 22 of gestation. At 5 months, the MFR offspring weighed significantly more, had reduced alveolar number, increased septal thickness, and decreased surfactant protein and phospholipid synthesis. These MFR-induced effects were normalized by the antiglucocorticoid MTP, suggesting that the stress of MFR causes hypercorticoidism, altering lung structure and function in adulthood.