Pentose phosphate pathway in cellular trophoblasts from full-term human placentas

Area of Science:

• Human placental biology
• Cellular metabolism
• Biochemistry

Background:

• Trophoblasts are crucial for placental function.
• Understanding glucose metabolism in trophoblasts is vital for fetal development.
• The pentose phosphate pathway plays roles in biosynthesis and redox balance.

Purpose of the Study:

• To investigate glucose metabolism via the pentose cycle in isolated human placental trophoblasts.
• To compare pentose cycle activity in freshly isolated cells versus cells cultured for 1 and 3 days.
• To assess the impact of methylene blue on pentose cycle activity.

Main Methods:

• Isolation of cellular trophoblasts from full-term human placentas.
• Measurement of 14CO2 yields from D-[1-14C]glucose and D-[6-14C]glucose to determine pentose cycle activity.
• Culturing cells for 1 and 3 days to observe changes in morphology and metabolism.
• Assessing pentose cycle activity with and without the electron acceptor methylene blue.

Main Results:

• Lactate was the principal product of glucose metabolism, accounting for ~75% of recovered 14C.
• Pentose cycle activity was low, ranging from 0.21% to 0.57% of glucose metabolized.
• Methylene blue significantly increased pentose cycle activity, reaching up to 18.2%.
• Cultured cells showed a decrease in basal pentose cycle activity over time but maintained high rates with methylene blue.

Conclusions:

• Pentose cycle activity is a minor pathway in freshly isolated and cultured human placental trophoblasts.
• Cultured trophoblasts retain the capacity for significant glucose oxidation via the pentose cycle, especially when stimulated.
• These findings contribute to understanding placental metabolic adaptations.