High glucose levels down-regulate glucose transporter expression that correlates with increased oxidative stress in placental trophoblast cells in vitro

OBJECTIVE: To study glucose transporter expression and oxidative stress in placental trophoblasts under hyperglycemic conditions in vitro. METHODS: Trophoblasts were isolated from term normal human placentas and incubated with Dulbecco's modified eagle medium containing 1000, 2500, and 4500 mg/L glucose for 3 days. At the end of incubation, culture medium was collected. Trophoblast RNA was extracted and mRNA expression of glucose transporters was determined by RNase protection assay. Messenger RNA expression for copper-zinc-superoxide dismutase (CuZn-SOD) was determined by real-time polymerase chain reaction. Lipid peroxide production was determined by measuring malondialdehyde concentration in the culture supernatant. Protein expression of sodium-glucose transporter 2 (SGLT-2) was determined by Western blot analysis. RESULTS: Messenger RNA expression for glucose transporter 1 (GLUT1) and SGLT-2 were reduced in trophoblast cells incubated with 4500 mg/L glucose compared with those incubated with 1000 and 2000 mg/L glucose. mRNA expression of CuZn-SOD was also decreased in trophoblasts incubated with 4500 mg/L glucose. Malondialdehyde production was significantly increased by trophoblasts incubated with 4500 my/L glucose compared with those by trophoblasts incubated with 1000 and 2000 mg/L glucose (4.69 +/- 0.60 versus 2.10 +/- 0.29 and 2.89 +/- 0.47 nmol/mg protein; P < .01, respectively). CONCLUSIONS: Down-regulation of gene expression of glucose transporters correlates with increased lipid peroxide production and decreased superoxide dismutase expression in placental trophoblasts cultured under hyperglycemic conditions. Copyright (C) 2004 by the Society for Gynecologic Investigation.