Plasma neurotensin in term and preterm neonates.

The new ileal peptide neurotensin has not been studied hitherto in the human neonate. Plasma concentrations of neurotensin were measured by radioimmunoassay in 276 healthy term or preterm infants either at birth or pre- or post-prandially during the neonatal period. In addition, a group of 10 6-day-old preterm infants were studied who had never been enterally fed on account of hyaline membrane disease. Plasma neurotensin values were obtained also in 12 healthy fasting adults. Term infants had higher plasma neurotensin concentration than preterm infants at birth. Both groups showed a significant postnatal surge in basal (pre-prandial) neurotensin concentrations exceeding adult values, but no postnatal neurotensin elevation was found in the unfed group. In preterm infants, who were studied further into the neonatal period than term infants, there was a progressive increase in the rise of neurotensin following a milk feed, with a massive neurotensin response by 24 days of age. In 6-day-old term infants, the neurotensin response to bottle feeding was significantly greater than to breast feeding. These findings add further weight to the concept that neurotensin may be of physiological importance as a gut hormone. The high neurotensin levels and large feed responses seen in neonates may indicate a unique role for neurotensin in early life.