Reversible Inhibition of Lung Cell Number After Glucocorticoid Injection Into Fetal Rabbits to Enhance Surfactant Appearance

Abstract

Recent enthusiasm concerning hydrocortisone therapy to prevent respiratory distress syndrome in human infants has aroused natural concern over possible untoward effects. There are both ethical and experimental reasons why human infants are not suitable for well-controlled investigation of untoward effects of steroid treatment. Therefore, we studied the effect of hydrocortisone injection on the lung cell number of the rabbit, an animal whose pulmonary development has been studied extensively. Fetal rabbits treated with single injections of hydrocortisone in utero had a lower number of lung cells when compared to similar weight controls. The decreased cell number, reflected by decreased DNA per lung, was also associated with lower lung weights and lower body weights but was not associated with significant changes in lung water or protein content. After birth, with adequate nutrition, "catch-up" in body weight occurred by 30 days' postnatal age. Animals killed at that time anti at 60 to 65 days had lung DNA content similar to untreated rabbits. Although lung cell number and body weight were decreased in fetal animals treated with a single dose of glucocorticoid late in gestation, with adequate nutrition growth of both body and lung recovered by 30 days' postnatal age.