Release of GI hormones in mother and infant by sensory stimulation.

It is well established that sensory stimulation is of great importance for the growth of and for the physiological and psychological development of infants. Supplementary sensory stimulation such as non-nutritive sucking and tactile stimulation has been shown to increase the growth rate and the maturation of premature infants. In human neonates non-nutritive sucking has a vagally mediated influence on the levels of some gastrointestinal hormones. In animal experiments afferent electrical stimulations of the sciatic nerves at low intensity leads to an activation of the vagal nerves and to a consequent release of vagally controlled gastrointestinal hormones such as gastrin and cholecystokinin. We therefore assume that both non-nutritive sucking and tactile stimulation trigger the activity of sensory nerves which leads to a release of vagally regulated gut hormones. Since gut hormones stimulate gastrointestinal motor and secretory activity and the growth of the gastrointestinal tract, and enhance the glucose-induced insulin release, they may contribute to the beneficial effects on maturation and growth caused by sensory stimulation. In the breast-feeding situation, the sucking of the child elicits similar reflexes in the mother leading to an activation of the maternal gut endocrine system and a consequent increase in energy uptake. These data indicate that many types of neurogenic reflexes induced in mother-infant interactions are of importance for the energy economy of both mother and child.