Comparison of the effects of dietary glucose versus galactose on porcine feto-placental glucose metabolism

The present study was conducted to determine whether dietary galactose can be used to improve glycogen and lipid accretion in fetal pigs. Pregnant gilts were fed diets containing either 24% glucose (control) or 24% galactose from d 98 to 110 of gestation. Gilts underwent abdominohysterotomy on d 110 of gestation. Slices of fetal subcutaneous adipose tissue and placenta were examined for metabolic capacity for glucose and for galactose utilization. No effects of maternal diet were evident upon glycogen content or enzyme activity of fetal semitendinosus muscle and liver. Maternal dietary galactose had no direct effects upon placental glucose oxidation or use for lipid synthesis. However, galactose supplementation of the incubation medium caused reductions in glucose oxidation (15%) and total lipid synthesis (24%) by the maternal placenta. Maternal dietary galactose caused an increase in total lipid (50%) and fatty acid synthesis (200%) from glucose in fetal subcutaneous adipose tissue; direct supplementation of galactose to the incubation medium had no effect on these parameters. The results of the present study suggest that feeding galactose to the pregnant gilt does not have direct effects upon placental metabolism or fetal glycogen storage. However, these data indicate that use of galactose in the maternal diet can result in an increase in the utilization of glucose for lipogenesis by fetal adipose tissue in swine. This effect is not a direct effect of galactose because transport across the placenta was not apparent.