Fig. 8

Hippocampal neurodegeneration is induced by intestinal inflammation in Sham-injured mice and exacerbated in TBI mice. One week following the cessation of DSS administration, ipsilateral hippocampal neuronal cell density was assessed by stereological quantification b–d. Representative images of cresyl violet stained brains a, (upper images) and neurons in the dentate gyrus (DG) region of the ipsilateral hippocampus a, (lower images, ×20 magnification) across all experimental groups. Quantification of neurons in the DG subregion revealed a significant increase in ipsilateral neuronal cell loss in the TBI + DSS compared to TBI mice. DSS administration also induced a significant loss in ipsilateral neurons in the DG in Sham+DSS compared to Sham mice b. A significant loss of ipsilateral neurons in the cornu ammonis (CA) 1 and CA2/3 hippocampal subregions was also observed in Sham+DSS mice compared to Sham mice. No significant changes in neuronal cell counts in the ipsilateral hippocampus of Naïve+DSS mice or in the contralateral hippocampus of all mice were observed b–d. Data expressed as mean ± s.e.m (cohort 2, n = 8–10/group). b * p < 0.0399 vs Sham ipsi, ** p < 0.0101 vs Naïve ipsi, ^^^^ p < 0.0001 vs Naïve+DSS ipsi, + p < 0.05 vs TBI ipsi, ++++ p < 0.0001 vs Sham ipsi, •• p < 0.05 vs TBI contra, ••• p < 0.001 vs Sham+DSS contra, •••• p < 0.0001 vs TBI + DSS contra. c ^^^^ p < 0.0001 vs Naïve+DSS ipsi, +++ p = 0.001 vs Sham ipsi, •• p < 0.05 vs Naïve+DSS/Sham+DSS contra. d ^^ p = 0.01 vs Naïve+DSS ipsi, +++ p = 0.001 vs Sham ipsi, • p < 0.05 vs Naïve+DSS contra, •• p < 0.05 vs Sham+DSS contra;. Abbreviations: contra, contralateral; CA, cornu ammonis; DG, dentate gyrus; ipsi, ipsilateral; mm, millimeter