Effects of fasting on gluconeogenic enzymes in the ovine fetus.

Fetal and maternal sheep were studied to determine whether changes in gluconeogenic enzyme activities could be detected in the liver and/or kidney associated with maternal nutritional deprivation. Thirteen ewes and 16 fetuses were sacrificed in the fed state, while 13 ewes with 17 fetuses were sacrificed after 5 days of fasting, all at 125 days gestation (term = 147 days). Fetal weight was decreased in the fasted versus fed group (2.86 +/- 0.56 versus 3.61 +/- 0.58 kg, p less than 0.001). Tissues were analyzed for glucose-6-phosphatase, fructose-1,6-diphosphatase, pyruvate carboxylase, phosphoenolpyruvate carboxykinase, glutamate oxaloacetate aminotransferase, and glutamate pyruvate aminotransferase. In maternal liver, four of the six enzymes increased significantly during fasting, whereas none of the enzymes increased in maternal kidney. In fetal hepatic tissue, five of the six enzymes (with the exception of pyruvate carboxylase) increased during maternal fasting and three of the enzymes increased in renal tissue. These data are consistent with the potential for increased rates of gluconeogenesis in the ovine fetus during periods of compromised maternal nutrition.