Figure 5.

Effect of magnesium treatment in mice with experimental S. pneumoniae D39 meningitis. (A) S. pneumoniae D39 concentrations (as CFUs) in blood, cerebellum and spleen homogenates after 36 h demonstrated comparable growth in infected mice treated i.p. with 0.45% NaCl (mock) or treated i.p. with MgCl₂ (Mg). (B) Relative fluorescent intensity measurement of the PSD95 immunofluorescence in layers 1–3 of the neocortex at the level of the postcentral gyrus (mock (n = 4 animals): NaCl‐injected and NaCl‐treated group; D39 (n = 19 animals): Spn D39‐infected and NaCl‐treated group; D39 + Mg (n = 18 animals): Spn D39‐infected and MgCl₂‐treated group; Mg (n = 3 animals): NaCl‐injected and MgCl₂‐treated group) and corresponding fluorescent images (cyan arrows indicate staining‐negative nuclear regions; green arrows – cortical surface; green lines limit the region of interest, including layer I and partially layer II; schematic diagram above indicates the position of the imaged fragment). Scale bar: 20 μm. (C) Clinical score (0 = no apparent behavioural abnormality; 1, moderate lethargy; 2 = severe lethargy; 3 = unable to walk; 4 = dead) of the animals. Mock and Mg controls demonstrate score of 0 (not included in the graph, overlap with axis). For statistical analysis, the area under the curve is calculated and compared (see Methods). There was a significant effect of treatment with Mg²⁺. (D) Survival curves of MgCl₂ (Mg, n = 18) or NaCl‐treated (mock, n = 19) infected animals. All mock and Mg controls demonstrate 100% survival at 36 h (not included in the graph, overlap of multiple lines). There was a significantly increased survival after treatment with Mg²⁺.