PLASMA VASOACTIVE INTESTINAL POLYPEPTIDE IN THE NEWBORN-INFANT

Vasoactive intestinal polypeptide (VIP) has been suggested as a possible contributor to the development of gastrointestinal problems. VIP is produced by nerve endings in the intestinal tract and appears to have marked effects on gut motility and its blood flow. Since necrotizing enterocolitis and feeding intolerance are common problems in the newborn, we examined the plasma VIP responses to feeding in healthy preterm and term newborn infants. Plasma VIP levels were measured in 20 full-term newborn infants (gestation of 39.4 ± 0.9 weeks, mean ± SD, and weight of 3,351 ± 477 g) and 38 preterm infants (gestation of 27-35 weeks, weight of 920-2,440 g). In term infants, cord blood samples were obtained from the umbilical artery and vein and then before and after the feed. For preterm infants, blood samples were obtained prior to the introduction of oral feeds during the first week, and then before and after feeding once a week over the next 4 weeks. Feeding ranged from diluted premature formula to special care (24 calories per ounce) for the preterm, and breast milk or regular commercial formula for the term infants. Twenty-one healthy adults, age 25-42 years, were studied for comparison. In the term newborn infants, the plasma VIP levels in the umbilical ve nous blood were lower, although not statistically significant (p = 0.06), than the umbilical arterial blood (10.78 ± 5.89 vs. 13.54 ± 6.71 pmol/L), suggesting placental metabolism of VIP. After birth, there was a significant increase in plasma VIP levels (18.89 ± 10.07 pmol/L, p = 0. 001). Introduction of formula or human milk did not cause any change in circulating VIP levels. The plasma VIP levels in the term newborn infants were significantly (p = 0.001) higher than those observed in normal adults (18.89 ± 10.07 vs. 6.04 ± 2.30 pmol/L). In the preterm infants, VIP levels during fasting were significantly lower (13.56 ± 8.67 pmol/L, p = 0.05) than those observed in term infants. There was a small statistically significant (p = 0.01) increase in VIP levels in the preterm infants during the second (17.41 ± 10.42 pmol/L) and third (16.63 ± 9.27 pmol/L) weeks after the introduction of feedings. The significance of the higher VIP levels in the newborn infants remains unknown. Because no infants developed gastrointestinal intolerance, no correlation between VIP levels and gastrointestinal problems could be demonstrated. © 1990 Raven Press, Ltd., New York.