Metabolic properties of astrocytes differentiated from rat neurospheres

The metabolic properties of astroglia differentiated from neurospheres have not been fully assessed. In this study, the glycolytic and oxidative metabolism of glucose in astroglia differentiated from rat tertiary neurospheres (astroglia(NS)) was compared with that in astroglia prepared from the striata of embryonic day 16 rats (astroglia(ST)). In addition to the basal condition, we also investigated energy metabolism under Na+,K+-ATPase activation. Furthermore, the effects of glucose concentration in the culture medium were assessed. No significant differences in 2-deoxy-D-[1-(14)C]glucose phosphorylation were observed between astroglia(NS) and astrogliaST. The rates of L-[U-14C]lactate ([14C]lactate) and D-[U-14C]glucose ([14C]glucose) oxidation were 5.74+/-0.82 and 2.83+/-0.4 pmol/60 min/microg protein, respectively, in astrogliaNS grown in low glucose (2 mM) and 3.01+/-1.03 and 1.77+/-0.23 pmol/60 min/microg protein, respectively, in astrogliaNS grown in high glucose (22 mM). Neither the [14C]lactate nor the [14C]glucose oxidation rates in astrogliaNS were significantly different from those in astrogliaST. D-aspartate (500 microM) significantly increased the [14C]lactate and [14C]glucose oxidation rates by 127% and 62%, respectively, in astrogliaNS grown in low glucose and by 217% and 115%, respectively, in astroglia(NS) grown in high glucose. D-aspartate also increased the oxidation of [14C]lactate and [14C]glucose to 236% and 147% of the control values, respectively, in astrogliaST grown in low glucose and to 174% and 144%, respectively, in astrogliaST grown in high glucose. Rat astroglia differentiated from neurospheres might possess an equivalent capacity for utilizing energy substrates under both basal and activated conditions to that of astroglia prepared from striatum.