MATERNAL DIETARY GLUCOSE LIPID INTERACTIONS MODULATE EMBRYOLOGICAL DEVELOPMENT IN-VIVO AND IN EMBRYO CULTURE

To examine the dietary interrelationships of glucose and lipid on embr yological growth and development, two levels of glucose (0% and 24%) a nd two types of lipid-soybean oil (SBO; 44.5% 18:2 [n-6]) or oleic aci d (OL; 6.7% 18:2 [n-6])-were fed to pregnant rat dams until Day 12.5 o f gestation, when developing embryos and maternal tissues were collect ed for analysis. In addition, Day 9.5 embryos were obtained from the d ietary treatment groups and cultured in vitro until Day 12.5 to ascert ain whether or not the embryos showed developmental changes in respons e to dietary treatment in the absence of maternal and placental factor s. Differences in energy intake and macronutrient composition explaine d differences in early placental weight; macronutrient composition, bu t not energy intake, accounted for differences in weight of in vivo em bryos and in morphological scores of cultured embryos. With food intak e as a covariate in the statistical analysis, the results showed that only the level of maternal dietary glucose influenced the number of li ve embryos and resorptions per litter. Both the level of carbohydrate and the type of lipid in the maternal diet, however, independently and interactively affected both embryonic growth and development in vivo and in culture. To evaluate the biological significance of this dietar y interaction, concentrations of essential fatty acids in the embryoni c and maternal tissues were measured. A striking result of this study was the rapidity of the diet-induced changes in tissue fatty acid comp osition. By gestational Day 12.5, the lack of glucose in the OL-based diet was associated with a raised 18:2 (n-6)/20:4 (n-6) ratio and a lo wered 20:4 (n-6) content in the embryo and the maternal liver. We sugg est that a carbohydrate-free maternal diet with apparently adequate le vels of essential fatty acid can contribute to embryonic growth retard ation both in vivo and in vitro by perturbing embryonic essential fatt y acid metabolism.