INCORPORATION OF RADIOACTIVITY FROM[C-14]LACTATE INTO THE GLYCOGEN OFCULTURED MOUSE ASTROGLIAL CELLS - EVIDENCE FOR GLUCONEOGENESIS IN BRAIN-CELLS

A pure population of astroglial cells was selected from heterogeneous astroglia-rich primary cultures in a medium containing sorbitol instea d of glucose. It was shown that astroglial cells synthesize glycogen w hen they are returned to a glucose-containing medium, and that when [C -14]lactate is also present the synthesized glycogen is radioactively labelled. Compared with the degree of incorporation of radioactivity i n the presence of tritiated glucose, the incorporation of radioactivit y from lactate was small but significant. After incubation of astrogli al cells with radioactively labelled lactate, the glycogen was isolate d and enzymatically hydrolysed to glucose, which was found to be radio actively labelled. Astrocytes are therefore able to convert lactate to glucosyl residues, a metabolic pathway known as gluconeogenesis. It i s proposed that astrocytic gluconeogenesis may consume lactic acid for med in neighboring cells such as neurons, during anaerobic glycolysis at times of high energy demand.