Glucose-6-phosphate dehydrogenase is present in normal and pre-eclamptic placental trophoblasts: Ultrastructural enzyme-histochemical evidence

The present study investigated the localization of glucose-6-phosphate dehy drogenase (G6PD) activity in the human placenta at various gestational ages . Placentae from patients with severe pre-eclampsia were also studied. Ultr astructural enzyme-histochemical analysis was performed by newly developed G6PD histochemistry using copper ferrocyanide as a capturing agent. Precipi tates indicative of G6PD activity were markedly visible in the cytotrophobl astic cytoplasm and faintly in the spncytiotrophoblastic cytoplasm of place ntae at various gestational ages, as well as those from pre-eclampsia. Freq uently, precipitations were localized on the cytosolic side of the endoplas mic reticular membranes of the cytotrophoblasts. Stringent cytochemical con trol experiments performed also ensured the specific detection of G6PD acti vity. The results indicated that cytochemically detectable G6PD was localiz ed in cytotrophoblastic cytoplasm. This enzyme may play significant roles i n the carbohydrate metabolism of the human placenta, and further maintenanc e of villous tree architecture. Combining the previous data, the human plac enta has many carbohydrate metabolizing-enzymes, similar to the adult liver . (C) 2001 Harcourt Publishers Ltd.