Fetal and Maternal Hormonal Response to Starvation in the Ewe

Abstract

SummaryFive ewes 90-130 days of gestation with chronically indwelling fetal catheters were studied. Blood samples were drawn each morning simultaneously from the maternal femoral artery, fetal femoral artery, and fetal umbilical vein. Total starvation was begun after blood samples had been drawn on the 3rd morning, but water was given ad libitum. The mean maternal arterial plasma glucose concentration before starvation (73.4 2 31.0 (SEM) mg/100 ml plasma HzO) fell to 54.8 f 5.2 mg/100 ml (P < 0.01) after 24 hr of fasting and to 37.5 + 1.6 mg/100 ml (P < 0.001) by 72 hr of fasting. The maternal arterial fructose concentration was low in both the fed (2.9 f 0.4 mg/100 ml) and fasted states (1.8 + 0.5 mg/100 ml, day 3). The maternal arterial insulin concentration fell early in fasting from a mean of 27.9 + 3.9 uU/ml on 2 days before starvation to 12.4 + 1.8 uU/ml after 24 hr of fasting (P < 0.005) and remained low for the duration of the 7-day fasting period. The mean maternal arterial glucagon concentration in the fed state was 112 + 20 pg/ml and did not change significantly throughout the 7 days of maternal fasting.Fetal arterial plasma glucose was much lower than maternal levels (mean 18.4 + 1.1 mg/100 ml plasma Hz0 in the fed state), decreased to 12.1 + 1.4 mg/100 ml after 24 hr of fasting ( P < 0.05) and did not change significantly after the 1st day of fasting.The whole blood fructose concentration in the fetal artery was high in the fed state (71.7 + 11.5 mg/100 ml, mean 2 days before fasting) and fell quickly during starvation (54.2 2 3.4 mg/100 ml after 48 hr). The fructose concentration did not change further for the duration of the fasting period. The fetal arterial insulin concentration was lower than the maternal (19.4 + 1.0 uU/ml in the fed state and did not fall dramatically after fasting as the mother did. After 24 hr of fasting, the fetal insulin was 15.0 + 1.5 uU/ml ( P < 0.005) and remained low throughout the fast. The umbilical venous-arterial differences of insulin were statistically different from 0 in both fed (mean -1.4 f 0.3 u U / d , P < 0.005) and fasted state (mean -1.4 + 0.5 uU/d, P < 0.02), with the fetal artery greater than the umbilical vein in 25 of 28 measurements. The fetal arterial concentration of glucagon was lower than in the ewe (32 f 7 pg/ml) and also did not change significantly during starvation.There was a good correlation of the plasma glucose and insulin concentrations for: both the fetus and the ewe. Analvsis of ~ooled fetal and maternal regression lines for insulin-glucos~relatidnships reveals no difference in the slow (maternal 0.48. fetal 0.48). but a statistically significant differeice'in the y intercept (mateinal -7.70, fetal 8.65, P < 0.005), with the fetal curve shifted to the left.The excellent correlation between plasma glucose and insulin concentration throughout the fed and fasted periods suggests that the decrease in fetal plasma glucose and the decreased utilization of exogenous glucose by the fetus is mediated by fetal insulin level. Although the respons...

Effects of meal intake on materno-foetal exchanges of energetic substrates in the pig

“…In agreement with earlier reports in sows [1,47] and ewes [51], fructose was not detected in significant amounts (< 0.1 mmol . L -1 ) in maternal blood at any sampling times.…”

Effects of Exogenous Glucagon on Concentrations of Glucose, Fructose and Insulin in Plasma of Sheep Fetus

“…Ep stein et al [12] found no increase in fetal glu cagon in the rhesus monkey made glucose intolerant with streptozotocin. Similar obser vations have been made in the fetal lamb, in which the concentration failed to change in response to fetal glucose infusion [15], In studies of chronic maternal fasting in the ewe, we found no significant change in the concentration of glucagon in fetal plasma during short-term fasting [37], but did find a trend towards an increased glucagon concen tration with a prolonged fast (more than 6 days) [36]. The purpose of this study was to investigate the effect of exogenous glucagon on fetal glucose, fructose and insulin in the sheep.…”

“…In 7 animals fetal samples only were obtained. Following a maternal fast of a minimum of 5 days, control values indicated that concentrations of glucose, fructose and insulin in fetal plasma were lower and of glucagon higher compared to the values when the ewe was fed, as has been pre viously reported [3,31,[35][36][37], Glucagon infusion into the fetus was then again per formed and the effects on the concentrations of glucose, fructose, insulin and glucagon in fetal plasma were similar to those found in the fed state. The fetal glucagon concentra tion ( fig.…”

Chronic late-gestation hypoglycemia upregulates hepatic PEPCK associated with increased PGC1α mRNA and phosphorylated CREB in fetal sheep

“…Another difference between this model and the models in which hepatic glycogen decreases is that fetal glucagon is not elevated in the hypoglycemic group (34). In a different lategestation fetal sheep model of nutrient deprivation, fetuses subjected to a five-day maternal fast had significantly lower fetal weight and maternal hepatic glycogen content but did not have different fetal glucagon concentrations or hepatic glycogen contents (29,59). In addition, piglets did not have lower liver glycogen contents following a maternal fast for the final 7 or 21 days of gestation (15), and unilateral ligation of the uterine artery in guinea pigs produced IUGR fetuses that had increased hepatic glycogen content (31).…”