Figure 2. THSG ameliorates glutamate-induced neuronal morphological change and excitotoxicity in primary cortical neurons. (A) Immunofluorescence images of treatment with or without various concentrations of THSG for 2 h followed with 100 μM L-glutamate for another 24 h; Staining performed with the primary antibody anti-MAP-2 (specific marker of neuronal dendrites, red) and a nuclear-specific dye DAPI (blue). Cells treated with L-glutamate for 24 h causes dendritic shrinkage; application of THSG 2 h prior to the treatment with glutamate improves the glutamate-induced neuron shrinkage. Merged images show the labeling co-localization. Scale bar = 100 μm. Cells were pre-treated for 2 h with THSG prior to treatment with L-glutamate for another 24 h; cell viability of primary cortical culture neurons was evaluated by MTT assay (B) and by lactate dehydrogenase (LDH) assay (C) (n = 4). Statistical analysis was carried out using ANOVA for repeated measures, followed by Tukey’s test of least significant difference. NS = no significant difference; *, P > 0.05; **, P < 0.01; ***, P < 0.001. (D) Gel electrophoresis showing the effects of THSG at a range of concentrations (3–300 μM) on L-glutamate-induced DNA fragmentation in primary cortical culture neurons.