KETOACIDS ATTENUATE GLUCOSE-UPTAKE IN HUMAN TROPHOBLASTS ISOLATED FROM FIRST-TRIMESTER CHORIONIC VILLI

OBJECTIVE: The objective of this study was to evaluate the hypothesis that ketoacids (acetoacetic acid and beta-hydroxybutyrate) diminish gl ucose transport in trophoblasts cultured from first-trimester chorioni c villi. STUDY DESIGN: First-trimester trophoblasts were obtained by t ransabdominal chorionic villus sampling for subsequent cytogenetic ana lysis. The cells were established as a continuous line exhibiting trop hoblast characteristics. Trophoblasts were cultured in Ham's F12/Dulbe cco's modified Eagle's medium (1:1) supplemented with 15% fetal bovine serum. Experiments were initiated by a 24-hour preincubation in serum -free Ham's F12/Dulbecco's modified Eagle's medium followed by incubat ion with ketoacids (acetoacetic acid and beta-hydroxybutyrate, 0 to 10 mmol/L) in the presence or absence of insulin-like growth factor-1 (1 00 ng/ml). The cells were challenged with 2-deoxy-[1,2-H-3]D-glucose ( 0.1 mmol/L) for 5 minutes and then cell-associated radioactivity was m easured. Total ribonucleic acid was extracted from cells incubated wit h ketoacids in the presence or absence of insulin-like growth factor-1 , and Northern blots were probed with a phosphorus 32-labeled compleme ntary deoxyribonucleic acid fragment encoding the rat GLUT 1. RESULTS: Ketoacids caused a dose-dependent inhibition of glucose transport. At 5 mmol/L acetoacetic acid there was a >50% reduction in the rate of g lucose transport in both control and insulin-like growth factor-1-trea ted cells. The diminution in glucose uptake by trophoblasts was not du e to cellular toxicity of the ketoacids because there was no significa nt difference in trypan blue exclusion or lactate dehydrogenase releas e between control and ketoacid-treated cells. Northern analysis reveal ed that the steady-state expression of GLUT 1 messenger ribonucleic ac id was diminished in ketone-treated cells, but this effect was overcom e by coincubation of cultures with insulin or insulin-like growth fact or-1. CONCLUSIONS: These results indicate that ketoacids can suppress the uptake of glucose into first-trimester human trophoblasts. Because ketoacidosis in pregnant women with diabetes mellitus is a frequent c linical consequence of poor metabolic control, it is possible that ele vated levels of acetoacetic acid and beta-hydroxybutyrate may impair t he transport of glucose across the placental trophoblast and into the fetal circulation.