The primary goal of this project is to measure long term effects of maternal diabetes mellitus, hyperglycemia, and hyperinsulinemia on maternal, placental, and fetal metabolism and on fetal growth. During the proposed research period, specific research aims will focus on certain metabolic conditions in the fetus and mother that appear to represent unique forms of """"""""glucose toxicity"""""""". Glucose toxicity refers to the 'down regulation"""""""" or """"""""suppression"""""""" of glucose-induced metabolic effects, specifically, glucose stimulation of pancreatic insulin secretion, tissue glucose sensitivity, tissue insulin sensitivity, genetic expression of glucoregulatory proteins, genetic expression of procoagulant and anticoagulant proteins, and cellular metabolism. Studies will be conducted with in vivo and in vitro techniques, using the pregnant sheep as an experimental model. In vivo metabolism will be controlled by short and long term glucose and insulin clamps, and quantified using Fick principle and radioactive and stable isotopic tracer methodology. In vitro studies will be conducted on tissues taken from the same animals after they are studied in vivo. Analyses of tissues will include body chemical composition, glucose carbon contribution to fetal carbon accretion using radioactive counting, gas chromatography/mass spectrometry stable isotope methodology, and nuclear magnetic resonance spectroscopy. Expression and regulation of glucoregulatory and coagulation proteins will use biochemical, cell and molecular procedures. Hepatocytes will be studied as isolated cells in suspension. Studies to date under this grant have been highly successful in the development of a chronic hyperglycemic model in the pregnant sheep and a more complete characterization of the effects of glucose and insulin on maternal and fetal metabolism. The proposed studies in the present competitive renewal application are direct extensions of these successful developments. They should provide new, unique, and important knowledge that will improve our understanding of how developmental aspects of metabolism are affected by chronic hyperglycemia. Also they will address new and important issues of the effect of hyperglycemia and hyperinsulinemia on the growth and development of selected fetal tissues, alteration in insulin sensitivity and glucose sensitivity, alterations in insulin secretion capacity, changes in the contribution of glucose carbon to fetal tissue carbon accretion, changes in the developmental production of certain glucoregulatory and procoagulant/anticoagulant proteins, and changes in hepatocellular metabolism. These unique studies will also provide fundamental knowledge about normal fetal development and the variability in fetal growth and pathophysiology that occur in human (and animal) diabetic pregnancies.
Showing the most recent 10 out of 37 publications
