Abstract
Cortical and cerebellar astrocytes were cultured in medium containing pentylenetetrazole (PTZ), a Ξ³βaminobutyric acid (GABA)~A~ receptor antagonist, for 3 weeks (up to 6 mM) or 2 hr (10 mM). Cells were incubated in medium containing [Uβ^13^C]glutamate (0.5 mM) and unlabeled glucose (3 mM) for 2 hr and cell extracts and media were analyzed by ^13^C magnetic resonance (MR) spectroscopy and highβperformance liquid chromatography (HPLC). When cerebellar astrocytes were incubated with PTZ for 2 hr, the amount of glucose removed from the medium and glucose and [Uβ^13^C]glutamate oxidation were decreased. Metabolism in cortical astrocytes was affected only slightly; amounts of glutathione and aspartate were decreased. When cerebellar and cortical cells were cultured in the presence of PTZ for 3 weeks, the amount of glucose removed from the medium and lactate formed were increased, indicating increased glycolytic activity. Despite the increased intracellular [Uβ^13^C]glutamate concentration in both types of astrocytes cultured with PTZ, labeled glutamine and glutathione were unchanged, indicating intracellular compartmentation. The amount of cellular protein was decreased at 6 mM PTZ for cerebellar astrocytes and 1 mM for cortical astrocytes, indicating a differential sensitivity to the effects of PTZ. In conclusion, mitochondrial metabolism and glycolysis were decreased by shortβterm incubation with PTZ in cerebellar astrocytes, whereas longβterm incubation affected both types of astrocytes, leading to increased glycolysis. Β© 2004 WileyβLiss, Inc.