CHPG treatment reduces the number of hypertrophic and bushy microglia in the injured cortex at four months post-injury. (A) Representative Iba-1 immunohistochemical images displaying each microglial activation phenotype. Microglia was reconstructed using Neurolucida software and classified into ramified, hypertrophic and bushy activation phenotypes based on cellular morphological features. Analysis of the difference between the three activation phenotypes indicated marked changes in dendritic length (Ai), branch thickness (Aii), number of branches (Aiii) and cell body volume (Aiv). ***P < 0.001 versus bushy, ###
P < 0.001 versus ramified, &
P < 0.05 versus hypertrophic, $
P < 0.05 versus ramified, ^P < 0.05 versus bushy. (B) Unbiased stereological quantification of microglial cell number and activation phenotype in each treatment group four months post-injury. There was no significant difference in the total number of microglia (Bi) in the injured cortex four months post-injury. CHPG-treated TBI tissue had significantly reduced numbers of hypertrophic (Biii) and bushy (Biv) microglia when compared to vehicle-treated TBI tissue, and increased numbers of ramified microglia (Bii). **P <0.01 versus vehicle,(n = 5/group). MTEP + CHPG-treated TBI tissue showed similar microglial phenotype profiles as the vehicle-treated TBI tissue, with fewer ramified microglia and more hypertrophic and bushy phenotypes. Statistical analyses were by one-way ANOVA with Student-Newman-Keuls post-hoc corrections in (A) and (B). Bars represent mean ± SEM.