The effect of non-nutritive sucking on plasma insulin, gastrin, and somatostatin levels in infants.

The aim of the present investigation was to study the effect of non-nutritive sucking on plasma levels of insulin, gastrin, and somatostatin in infants. These hormones were measured with radioimmunoassay in plasma collected from fullterm and preterm infants sucking a pacifier. In fullterm infants, sucking caused a significant increase of insulin levels from 13 +/- 10 microU/ml to 40 +/- 36 microU/ml and 21 +/- 17 microU/ml after 45 sec and 5 min respectively, from when the infants started sucking. A similar pattern was seen in preterm infants. In contrast, gastrin and somatostatin levels were not significantly affected. We suggest that sucking causes an activation of the vagal nerve, which results in the release of insulin. We also suggest that in infants, oral feeding is superior to bolus feeding, since in the latter case no vagal activation and consequently no release of hormones with anabolic properties occurs.