The endocrinology of feeding in the newborn.

During the last 20 years there has been an explosion of interest in and knowledge of hormones and regulatory peptides manufactured by specialized cells in the gut. Evidence has been presented in this chapter to suggest that these substances have essential roles to play in the effective utilization of food in the human adult, and that they also have an essential role to play in the differentiation and functional development of the fetal gut. It is, perhaps, during the days immediately following birth that they have their greatest and most important influence, in determining the successful adaptation to postnatal enteral feeding. There is good evidence to show that the initiation of enteral feeding is an important environmental trigger which provokes massive surges in the concentrations of these peptides in the first postnatal days in both premature and full term infants. The mode of administration and the composition of feeds have further influences, whilst deprivation of enteral feeding prevents the appearance of postnatal hormonal surges. In view of the fact that sub-nutritional volumes of milk are capable of inducing these surges, the concept of minimal enteral feeding in seriously ill premature and full term infants and even the therapeutic use of regulatory peptides warrants further investigation. Finally, it is evident that much more study is required to define the ontogeny, regulation of secretion, interaction and mechanism of effect of these fascinating substances.