Selective Nutrient Feeding Induces Maturation of Gastrointestinal Hormone Release in Preterm Infants • 1498

Abstract

We have previously shown that preterm infants given small enteral feedings have higher plasma concentrations of gastrin and gastric inhibitory peptide(GIP), while plasma concentrations of peptide YY (PYY) are unchanged. In adults, the ingestion of protein stimulates the release of gastrin which, in turn, stimulates the release of acid and stimulates an increase in gastroduodenal motor activity. Carbohydrate stimulates the release of GIP which regulates plasma glucose and inhibits small intestinal motor activity. Fats stimulate the release of PYY which inhibits small intestinal motor activity. We speculated that feeding babies with selective nutrients would induce hormone release in preterm infants as they do in adults, and, thus, enhance gastrointestinal function. Eighty preterm infants 25 to 30 wks gestation admitted to the Newborn Intensive Care Unit at Ben Taub General Hospital were fed 24 ml/kg/d for the first 10 days they received enteral feedings in addition to parenteral nutrition. Infants were given one of 4 formulas: full 24 cal/oz formula (n=20), its carbohydrate (n=20), protein(n=20), or fat component (n=20), all fed in 4 hr cycles consisting of 2 hr infusions interrupted by 2 hrs of fasting. On the tenth study day, blood was drawn to determine fasting plasma concentrations of gastrin, GIP, and PYY. In addition, motor responses to a full strength formula feeding were assessed via a low compliance continuous perfusion manometry. Compared to values seen at birth, fasting plasma concentrations of gastrin increased by feeding day 10 among infants fed protein, fat, or full formula (all p<0.05, paired t test) but not carbohydrate. GIP plasma concentrations increased in babies fed carbohydrate or full formula (both p<0.05) but not fat or protein. Plasma concentrations of peptide YY did not change in any feeding group. No group of study infants displayed the presence of a motor response to feeding before enteral feedings were begun. Babies fed protein or full formula displayed motor responses to feeding after 10 days of feeding while babies fed carbohydrate and fat did not. We conclude that the release of gastrointestinal hormones in response to selective nutrients is present in preterm infants, as well as motor responses to feeding that are mediated by those nutrients. We speculate that designing formulas that trigger intestinal hormonal release may be useful in enhancing the infant's endogenous mechanisms to improve gastrointestinal function.