AJP - Lung Cellular and Molecular Physiology, Vol 257, Issue 2 94-L99, Copyright © 1989 by American Physiological Society
Thyroid inhibition and developmental increases in fetal rat lung antioxidant enzymes
I. R. Sosenko and L. Frank
Division of Neonatology, Calvin and Flavia Oak Asthma Research and Treatment Facility, Miami, Florida 33101.
After demonstrating that prenatal exogenous thyroid hormone administration
to pregnant rats produces decreases in fetal lung antioxidant enzyme (AOE)
development despite increases in surfactant development, we examined the
role of endogenous thyroid hormones on the development of these two lung
systems. We administered the antithyroid drug methimazole (or diluent) to
pregnant rats for the final 3 days before premature or term delivery; in a
second series of experiments, propylthiouracil was administered for the 10
days before delivery. Both antithyroid drugs, known to cross the placenta,
produced significantly decreased thyroid hormone levels in the pregnant
dams. Fetal offspring from methimazole-, and propylthiouracil-treated dams
demonstrated significant increases in pulmonary superoxide dismutase
activity at 20 and 21 days of gestation and in catalase and glutathione
peroxidase activities at 21 days compared with control offspring.
Surfactant, measured as lung tissue disaturated phosphatidylcholine, was
not different between either experimental group and controls. These results
suggest that thyroid blockade increases AOE because the influence of
thyroid hormone on AOE development may be one of depression. The findings
confirm that certain hormonal regulators may influence different developing
fetal lung systems in different ways.
