Figure 2.

Effects of Aβ on astrocyte metabolism. A–F, Astrocytes were stimulated with 25 μm Aβ_25-35 for 48 h and the following metabolic parameters were evaluated: A, Lactate release. Results are expressed as percentage of control (Ctrl) values (140.1 ± 15.2 nmol/dish) and are means ± SEM of at least 23 determinations from at least eight independent experiments. B, Glycogen levels. Results are expressed as percentage of Ctrl values (35.9 ± 2.2 nmol/ dish) and are means ± SEM of at least 12 determinations from at least four independent experiments. C, CO₂ production in the PPP and the TCA cycle. Results are expressed as percentage of Ctrl values for the total production of CO₂ (0.0302 ± 0.0075 nmol of CO₂ per dish per min) and are means ± SEM of at least six determinations from at least three independent experiments. D, Hydrogen peroxide production. Results are expressed as percentage of Ctrl values (0.75 ± 0.08 μm) and are means ± SEM of at least 20 determinations from at least four independent experiments. E, Intracellular glutathione (GSH) content. Results are expressed as percentage of Ctrl values (17.1 ± 1.3 nmol/dish) and are means ± SEM of 12 determinations from four independent experiments. F, Extracellular glutathione (GSx) content. When indicated, the γ-glutamyl-transpeptidase inhibitor acivicin (100 μm) was added 1 h before Aβ_25-35 and maintained throughout the whole incubation. Results are expressed as percentage of Ctrl values without acivicin (0.76 ± 0.12 nmol/dish) and are means ± SEM of at least eight determinations from at least three independent experiments. All data were statistically analyzed with t test (** and ⁺⁺p < 0.01; *** and ⁺⁺⁺p < 0.001; ns, not significantly different from Ctrl). For C and F, asterisks refer to total CO₂ production and acivicin conditions, respectively; cross marks refer to CO₂ production in TCA cycle and basal condition (without acivicin), respectively.