Increased Synthesis of Tumor Necrosis Factor-α in Uterine Explants From Pregnant Diabetic Rats and in Primary Cultures of Uterine Cells in High Glucose

The production of tumor necrosis factor-α (TNF-α) was investigated in uterine explants from normal, diabetic, or insulin-treated diabetic pregnant rats. Explants from diabetic rats released more soluble TNF-α than did those in the other groups. The extent of this secretion was correlated with blood glucose concentration at the time of explantation. The concentration of cell membrane–associated TNF-α in the explants was not altered by diabetes. Daily insulin administration failed to normalize uterine TNF-α secretion despite correction of glycemia in the diabetic rats. Explants from normal pregnant rats cultured in vitro with increasing concentrations of D-glucose showed a dose-dependent increase in TNF-α secretion. The production of TNF-α in high glucose was also tested in primary cultures of uterine cells isolated from either immature or adult rats. TNF-α secretion was increased in high D-glucose but not in iso-osmolar concentrations of L-glucose, D-raffinose, D-galactose, or mannitol. Cell membraneassociated TNF-α was not influenced by high D-glucose. Semiquantitative reverse transcription–amplification of RNA extracted from primary cultures of uterine cells showed that the steady-state level of TNF-α transcripts was increased by high D-glucose but not by high L-glucose. The results are consistent with the hypothesis that hyperglycemia is instrumental in the overexpression of TNF-α in the diabetic uterus. Because TNF-α has a demonstrated negative impact on embryonic growth, enhanced TNF-α synthesis in the pregnant uterus may contribute to the embryopathy associated with maternal diabetes.