Exposure to the mold Stachybotrys alters microglial morphology differentially in CA1 and CA2-3 of the dorsomedial hippocampus

Abstract

Our labs have developed a mouse model to study the neural basis of cognitive impairments following exposure to mold. Here, we compared the effects of mold exposure on individual microglial parameters across subregions of the dorsomedial hippocampus. Adult male C57Bl/6 mice were exposed to either intact spores (IN), extracted spores (EX), or saline vehicle (VEH). Extracted spores had their toxins removed and proteins denatured leaving the spore casing, thereby simulating spore components remaining after commercial mold abatement. Iba1 + cells were visualized using immunohistochemistry. Cell body contours in CA1 and CA2-3 (combined) were traced using Neurolucida (Microbrightfield). Standard Neurolucida contour parameters were compared across treatments and between hippocampal regions. In CA1, 2, 3 combined, cells were rounder and more compact in the IN group than in EX. EX cells had a more complex perimeter (form factor) than VEH or IN. Within the VEH group, cell bodies in CA1 were larger and more round than in CA2-3. There were no differences in any of the measured parameters between CA1 and CA2-3 in IN mice, and a different pattern of differences in parameters between CA1 and CA2-3 in EX mice. No differences in microglial density were found across hippocampal regions or treatments. In sum, both IN and EX mold treatment gives rise to characteristically different phenotype profiles of microglia in the hippocampus, specific to CA1 and CA2-3 subregions.