Glucose-6-phosphatase is present in normal and pre-eclamptic placental trophoblasts: ultrastructural enzyme-histochemical evidence.

The purpose of the present study was to localize glucose-6-phosphatase (G6Pase) activity in the human placenta at various gestational stages and to compare them to pre-eclamptic placenta activity. Ultrastructural enzyme-histochemical analysis of G6Pase was performed using cerium and lead as capturing agents. Precipitates indicative of G6Pase activity were observed in the endoplasmic reticulum and the nuclear envelope of the syncytiotrophoblasts in near-term placenta obtained from women with normal pregnancies. In placenta taken from women with severe pre-eclampsia, the localization pattern, enzyme activity intensity, and morphology of the endoplasmic reticulum did not differ from normal pregnancies. Stringent control experiments were performed also to ensure specific detection of G6Pase activity. The results indicate that cytochemically detectable G6Pase is present in the human placenta. This enzyme may play significant roles in carbohydrate metabolism in the human placenta.