Bacterial Cytolysin during Meningitis Disrupts the Regulation of Glutamate in the Brain, Leading to Synaptic Damage
Figure 2
Reduced synaptic density in mouse pneumococcal meningitis neocortical brain tissue samples.
A. Reduced synapsin staining in layers I–II of the neocortex in animals with meningitis by PLY-producing bacteria vs. all other groups 36 h after injection. * p<0.05. (D39) indicates the group of mice injected intracerebrally with the pneumolysin (PLY)-producing D39 S. pneumoniae strain; (PLY-) mice indicates those infected with the PLY-deficient D39 strain. B. Reduced staining was observed for PSD95 in layers I–II of the frontal neocortex of mice injected with the PLY-producing strain vs. the PLY-deficient D39 strain animals after 36 h. All values are presented as the mean ± SEM. There were 5 animals in the mock group and 10–13 in the meningitis group. C. Representative tissue sample images with anti-synapsin I immunohistochemistry of layers I–III with magnification of equivalent areas of interest in layer I. Scale bar: 15 µm. D. Representative images of the TUNEL-FITC staining of equivalent areas in layers I/II of the neocortex of mice infected with D39 and PLY-deficient pneumococcal strain, where no TUNEL-positive cells are present. All nuclei were counterstained with propidium iodide (PI). TUNEL-negative control (enzyme missing) and TUNEL-positive control (pretreatment with DNAseI) are presented for staining validation. Scale bar: 20 µm.