Fig. 4

Increased microgliosis and astrogliosis in the postnatal amygdala after MIA. Iba-1 immunoreactivity in the saline and LPS-treated animals also displayed distinct differences revealing clear changes in cell morphology. At higher magnification (insets of panels a, c, and e), Iba-1-positive cells display ramified morphologies in saline-treated animals, whereas in LPS animals, they are more widely distributed and exhibit amoeboid morphology (large cell body with thick stunted processes). Representative images (b) of Iba-1 positive microglia that were quantified; morphologies of microglia: top panel shows a ramified microglia with long processes; lower panel shows microglia with thick cell body, stunted processes and amoeboid morphology (b). Counts of Iba-1-positive microglia showed higher percentage of amoeboid-like microglia at P7 and P40 in LPS-treated groups in comparison to saline-treated controls with no significant differences seen at P14 (b, d and f). GFAP immunoreactivity was sparse in saline animals especially at earlier postnatal ages; however, it increased considerably in the LPS-treated animals (g, h and i). Astrocyte territories overlap and exhibit cellular hypertrophy indicative of astrogliosis at P14 (h, bottom inset) and P40 (i, bottom inset). Semi-quantitative scoring of GFAP staining intensities showed that the amygdala had higher GFAP score at P14 in the LPS-treated groups (j). Across the ages examined, LPS-treated groups had relatively higher GFAP staining intensities in comparison to saline control animals (j). Density of GFAP-positive cells and variation in the staining intensity (somata and cellular processes) were included into scoring in a blinded manner as − = none (0% stained), + = very few cells (< 10% of area stained), ++ = few cells (10–25% of area stained), +++ = moderate number of cells (25–50% of area stained), and ++++ = numerous cells (> 50% stained) (j). Scale bar = 200 μm with inset images scale bar = 50 μm. Significant difference denoted as *p < 0.05, **p < 0.01, and ***p < 0.001