Figure 3.

Memantine prevents Tat-induced cell death without affecting synapse loss. (A) Cell death was measured with the PI fluorescence assay described in Methods. Bar graph summarizes PI uptake in neurons 48 h after no treatment (control), treatment with 1 mM glutamate, or treatment with 50 ng·mL⁻¹ Tat in the absence (untreated) or presence of 10 µM memantine as indicated. PI fluorescence was normalized to 1 mM glutamate treatment. Data are expressed as mean ± SEM. *P < 0.05 relative to control, ^###P < 0.001 relative to Tat treatment alone (anova with Tukey's post-test). (B) Representative processed images of neurons incubated with 10 µM memantine before (0 h) and after (24 h) no treatment (Mem alone) or treatment with 50 ng·mL⁻¹ Tat (Mem + Tat). The insets are enlarged images of the boxed region. Scale bars represent 10 µm. (C) Bar graph summarizes changes in PSD-GFP puncta (PSDs) after 24 h treatment under control conditions (solid bars) or following treatment with 50 ng·mL⁻¹ Tat in the absence or presence of the indicated concentration of memantine. Data are expressed as mean ± SEM. ***P < 0.001 relative to control (Student's t-test).