Figure 4
CA1 neurons undergo apoptotic cell death in B6 mice but not in SJL mice during acute TMEV infection.
Hippocampal sections from B6 (A) and SJL mice (B) were processed for TUNEL staining to mark apoptotic cells at 4 dpi. The majority of TUNEL-positive cells were localized to the CA1 pyramidal layer of the hippocampus in B6 mice (A), consistent with the observation that these neurons die within the first few days of infection. In contrast, very few TUNEL-positive cells were observed in the CA1 region of SJL mice (B), suggesting that neurons in the hippocampus do not die in these animals. The large number of TUNEL-positive cells scattered throughout the brain frequently colocalize with histological markers of inflammation. (C) Primary hippocampal neurons cultured from B6 mice (solid circle) and from SJL mice (empty circle) were exposed to various concentrations of H2O2 to determine sensitivity to oxidative injury-induced cell death using an MTT survival assay. Data are shown as percent of untreated MTT reaction product following spectrophotometric analysis of cell lysates. While there was a trend toward greater sensitivity to oxidative injury in neurons derived from SJL mice, this outcome is opposite to the prediction that increased neuron death in B6 mice is due to heightened sensitivity to apoptosis. The scale bar in B is 500 μm and refers to all panels. Sections are representative of at least 5 mice per group across multiple (>3) experiments.
