[Prenatal prevention of infant respiratory distress syndrome. 1st part: experimental data and pharmacological treatment].

Pulmonary maturation and growth are two time-related interdependent phenomena. The main regulatory mechanisms of pulmonary maturation are complex and the role of epithelial-mesenchymal interrelationship appear to be determinant in the phenomena leading to morphological growth of the lung and in cellular differentiation of the epithelium during development. At an early stage of morphological development of the fetal lung, endogenous hormones do not directly affect epithelial differentiation but modulate the expression of genes coding for surfactant. Later surfactant production responds to multihormone regulation. Some of these hormones or growth factors (steroids, oestradiol, prolactin, thyroxine, epidermal growth factor, fibroblast pneumocyte factor) are powerful stimulators, favoring biochemical development of the fetal lung. Inversely, other factors (insulin, androgens) limit the production of surfactant. Glucocorticoids play a specific role (stimulation of morphologic and biochemical development of the lung) and potentialize the stimulating effect of other factors. A good understanding of these mechanisms is essential before introducing treatments stimulating natural processes as closely as possible. Experimental results on the use of lung maturation induction, especially with glucocorticoids, have been quite promising. Combining thyroid hormones and thyrotropin-releasing hormone appears to be an interesting proposal, as is the use of growth factors such as epidermal growth factor.