Enteral feeding in utero induces marked intestinal structural and functional proteome changes in pig fetuses.

Intestinal adaptation from parenteral to enteral nutrition is crucial for survival and growth of newborns. Rapid feeding-induced gut maturation occurs immediately after birth in both preterm and term neonates, but it remains unclear whether the responses depend on factors related to birth transition (e.g. bacterial colonization, endocrine, and metabolic changes). We hypothesized that enteral feeding matures the immature intestine, even in fetuses before birth. Hence, control pig fetuses were compared with fetuses fed with milk formula for 24 h in utero. Gel-based proteomics showed that feeding-induced changes in 38 proteins, along with marked increases in intestinal mass and changes in activities of brush border enzymes. Physiological functions of the identified proteins were related to enterocyte apoptosis (e.g. caspase 1) and nutrient metabolism (e.g. citric acid cycle proteins). Many of the differentiated proteins were similar to those identified previously in preterm pigs fed with the same formula after birth, except that effects on proteins related to inflammatory lesions (e.g. heat shock proteins) were absent. Our results show that enteral feeding, independently of the birth transition, induces marked gut maturation and proteome change in the immature intestine. Hence, immediate postnatal feeding-induced gut changes are largely independent of factors related to the birth transition.