Hormonal regulation of perinatal enzyme differentiation in the mammalian liver.

The adaptation of newborn mannals to extrauterine life depends in large part on the maturation of biochemical and physiological functions during perinatal development. Hormones such as glucocorticoids, catecholamines and glucagon can stimulate enzyme induction during development; on the other hand, insulin has been shown to antagonize these stimulatory effects. Only the surface of the problem of hormonal regulation of enzyme differentiation during the perinatal period has been reached, especially as regards human development. Each enzyme presents unique problems of chemical regulation; the functional consequences of these factors are not exactly the same in each tissue and perhaps not in each species. The possibility of using inducing agents such as hormones, drugs and substrates to promote biochemical enzyme differentiation is a new and exciting aspect which needs to be explored further as a means of facilitating survival and ensuring optimal extrauterine development of the immaturely born human infant or the full-term infant with delayed-enzymic development. However, any intervention in the carefully programmed interplay of different hormones which regulate normal enzymic adaptation and development during the perinatal period should be undertaken only after careful consideration. The possibilities of long-term harm must be weighed against short-term benefits.