Fig. 5.

Obesogenic conditions in adolescence promote significant expansion of 'intermediate' microglia phenotype and TNF-α expression. Principal component analysis (PCA) and K-means clustering were used to generate three unique microglial phenotypes based on lacunarity. (A) Representative images of the three distinct morphological phenotypes: Hyper-ramified, Intermediate, and Hypo-ramified. The experimental conditions significantly altered the microglial cell distribution based on lacunarity (n, χ², df, p; 6,49, 1982, 6, p < 0.0001). Hypo-ramified and intermediate phenotypes increased in response to the WD and PSS, while the amount of hyper-ramified cells was reduced. (B) Hippocampal TNF-α gene expression was shown to be significantly influenced by both the WD (p = 0.021) and PSS (p = 0.0014). Relative to UNEX controls, PSS exposure significantly increased hippocampal TNF-α gene expression in CD (p = 0.0110) and WD (p = 0.0028) fed rats. Sample size: histology: 4 rats/group, 16,487 Iba-1+ cells; RT-PCR: 3 rats/group.