Maternal undernutrition during the periconceptual period increases plasma taurine levels and insulin response to glucose but not arginine in the late gestational fetal sheep.

Maternal undernutrition throughout gestation impairs pancreatic function in the offspring. The influence of periconceptual maternal undernutrition on fetal insulin responses to secretogues in late gestation is unknown. Romney ewes were fed concentrates at 1-2% of body weight/d (UN) or 3-4% of body weight/d (N) from -61 d to +30 d from mating. From 30 d gestation all ewes were fed at 3-4% of body weight/d. At 119 d gestation singleton fetuses (UN; n = 12, N; n = 10) underwent intravenous glucose (1.5 g) and arginine (300 mg) challenge tests. Paired maternal and fetal blood samples were collected over 60 min. Fetal plasma insulin area under the curve (AUC) was larger in UN than in N fetuses during glucose challenge (4.5 +/- 0.6 vs. 2.9 +/- 0.5 nM, p < 0.05) but was not different during arginine challenge. Maternal and fetal plasma taurine concentrations were higher in UN than N (maternal; 110 +/- 11 vs. 75 +/- 8 microM, fetal; 99 +/- 13 vs. 56 +/- 5 microM, both p < 0.05). Maternal periconceptual undernutrition influences fetal insulin secretion without affecting fetal size. The larger plasma insulin responses in UN fetuses could reflect accelerated maturation of pancreatic beta cells or an alteration of other mechanisms regulating insulin secretion. The role of taurine in fetal pancreatic beta cell development requires further investigation.