Differential expression of glutamate dehydrogenase in cultured neurons and astrocytes from mouse cerebellum and cerebral cortex.
Glutamate dehydrogenase (GDH) specific activities, kinetic properties and allosteric regulation were studied in extracts from cultured neurons and astrocytes prepared from mouse cerebral cortex and cerebellum. Considerable differences were observed in the specific activity of the enzyme among the different cell types with astrocytes expressing the highest GDH activity. This may reflect the functional importance of these cells in glutamate uptake and metabolism. Among the neurons, the glutamatergic cerebellar granule cells showed a GDH specific activity that was 60% higher (P < 0.01) than that of the GABAergic cerebral cortical neurons. Also, the K(m) for ammonia was 1.7-fold higher in the cortical neurons than in the other cell types. These findings may reflect a particular need for the glutamatergic granule cells to synthesize glutamate via the GDH pathway. No differences were observed among the different cell types with regard to the allosteric properties of GDH expressed by these cells.
Zaganas
I
I
Department of Neurology, School of Health Sciences, Section of Medicine, University of Crete, Heraklion, Crete, Greece.
Waagepetersen
H S
HS
Georgopoulos
P
P
Sonnewald
U
U
Plaitakis
A
A
Schousboe
A
A
D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000201:enzymology*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000201:enzymology*; D002540:Cerebral Cortex / Q000166:cytology / Q000201:enzymology*; D005969:Glutamate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000201:enzymology*
D018698:Glutamic Acid; D000244:Adenosine Diphosphate; D006160:Guanosine Triphosphate; D005969:Glutamate Dehydrogenase