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Utilization of mannose by astroglial cells
R Dringen1, K Bergbauer, H Wiesinger
1Physiologisch-chemisches Institut der Universität, Tübingen, Germany.
Neurochemical Research
|January 1, 1994
Summary
Mannose enters brain astroglial cells via the glucose transporter and is converted to fructose-6-phosphate. This metabolism produces glycogen and lactate, with insulin enhancing glycogen production.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Astroglia are crucial support cells in the brain.
- Understanding nutrient metabolism in astroglia is vital for brain function.
Purpose of the Study:
- To investigate the uptake and metabolic fate of mannose in primary astroglial cultures.
- To elucidate the specific pathways and enzymes involved in mannose metabolism within astroglia.
Main Methods:
- Primary cultures of neonatal rat brain astroglia were used.
- Mannose uptake kinetics were analyzed.
- Enzyme activities (hexokinase, mannose-6-phosphate isomerase) were measured.
- Metabolic products (glycogen, lactate) were quantified.
Main Results:
- Mannose uptake exhibited both saturable and non-saturable components, inhibited by glucose and specific inhibitors.
- Mannose was phosphorylated to mannose-6-phosphate, then isomerized to fructose-6-phosphate.
- Mannose-6-phosphate isomerase activity exceeded hexokinase activity.
- Glycogen and lactate were identified as major mannose metabolites.
- Insulin specifically enhanced glycogen synthesis from mannose.
Conclusions:
- Astroglial cells utilize the glucose transporter for mannose uptake.
- Mannose is metabolized to fructose-6-phosphate within astroglia.
- The findings provide insights into astroglial carbohydrate metabolism and potential therapeutic targets.