Fig. 1.

NAC protects astrocytes from proteasome inhibitor–mediated cell loss. Primary cortical astrocytes were treated with vehicle (dimethylsulfoxide) or a range of MG132 concentrations in the presence of 3 mM NAC or vehicle (equivalent v/v H₂O). (A) Viability was determined 48 hours later by blinded counts of Hoechst⁺ nuclei. (B) Representative images of Hoechst⁺ nuclei. (C) Representative images of astrocytes stained for S100β (green) and glial fibrillary acidic protein (GFAP, red). Nuclei were labeled with Hoechst (blue). (D) Proteasome activity was determined by monitoring the production of AMC from Suc-LLVY-AMC in lysates prepared from cells 0.5 hours after application of NAC, MG132, or their respective vehicles. Proteasome activity data are expressed as a function of protein content in each sample. Shown are the mean ± S.E.M. values of 3–6 independent experiments. *P ≤ 0.05; ***P ≤ 0.001 versus 0 µM MG132; ⁺⁺P ≤ 0.01; ⁺⁺⁺P ≤ 0.001 versus 0 mM NAC, two-way analysis of variance followed by the Bonferroni post hoc test.