Gastrointestinal permeability changes in the preterm neonate.

Abstract

SUMMARY The lactulose/L-rhamnose urinary excretion ratio during continued infusion of milks containing both sugars was used as an index of the permeability of the neonatal bowel to large and small molecules. Healthy infants of gestational age 31-36 weeks proved to have a period of enhanced permeability to lactulose during the first week of life, the lactulose/L-rhamnose excretion ratio being significantly higher on day 2 than on days 9 or 16 when a mature pattern of permeability could be seen. In infants traumatised by asphyxia or sepsis this change was much less pronounced. Healthy preterm infants of gestational age 26-29 weeks showed a 'mature' pattern of permeability at birth, followed by a temporary period of enhanced permeability after 3-4 weeks of life. It is proposed that enhanced permeability to larger molecules is a specific temporary condition of the neonatal bowel in man as in other mammals, but the immunological implications in man remain to be established.

Intestinal Permeability and Carrier-Mediated Monosaccharide Absorption in Preterm Neonates during the Early Postnatal Period

“…This property of the epithelium can be assessed indirectly by determining the intestinal permeability to orally administered water-soluble molecules, such as lactulose and L-rhamnose (9, 10). It has previously been shown in preterm neonates that the permeability changes during the first month after birth, and that it may be affected by enteral nutrition (11)(12)(13). However, these studies did not investigate the permeability during the immediate postnatal period, or did not discern between preterm neonates of different gestational ages.…”

Early Dietary Antigens Delay the Development of Gut Mucosal Barrier in Preweaning Rats

“…The intestinal permeability to macromolecules is transiently increased postnatally (14,15). Gut closure, the cessation of enhanced neonatal macromolecular absorption, occurs as a result of active maturational events in gastrointestinal development (10).…”

“…In humans, the precise mechanisms of intestinal maturation remain elusive. There is increasing evidence to suggest that a period of enhanced intestinal permeability and macromolecular uptake also exists in the human newborn (14,19).…”

Mechanistic bases for differences in passive absorption

“…Differences in paracellular permeability are not limited to between species, but also within species [e.g. human diseased states (Vogelsang et al, 1998); human developmental stages (Beach et al, 1982)]. …”