Upregulation of nutrient transport in fetal rabbit intestine by transamniotic substrate administration

Delivery of nutrients to the developing fetal gastrointestinal tract has been advocated as a potential prenatal treatment for intrauterine growth retardation. To examine the effect of intrauterine nutrient administration on the uptake capacity of the intestine, 16 maternal rabbits underwent bilateral ovarian-end transamniotic catheter placement on gestational Day 24. Study fetuses received a galactose solution; the contralateral controls received mannitol, a physiologically inert carbohydrate. Infusions were continued until Day 30 when an everted sleeve technique was used to measure radiolabeled uptake of both galactose and glucose in the proximal, middle, and distal small intestine. Mucosal scrapes were obtained, weighed, and the percentage of weight was calculated. Results were analyzed by ANOVA and Student's t test with P less than 0.05 being considered significant. There were 2 maternal deaths with 11 fetal pairs surviving (79%). There was increased uptake of galactose in the study fetuses compared to controls reaching significance in the middle and distal segments. Similarly, glucose uptake was significantly increased in the proximal and distal segments. Mucosal weight was increased in all regions, reaching significance in the proximal segment. Total intestinal uptake of galactose and glucose was significantly increased in the study fetuses compared to controls. Intraamniotic galactose infusion caused not only upregulation of its own mucosal transport but also that of glucose, along the entire fetal small intestine, achieving statistical significance particularly in distal segments. Fetal implications for transamniotic feeding are under investigation.