The Effects of Orai1 Channel Deletion in the Microglial Morphology of Mice

Microglia, the brain’s resident macrophages, shift between surveillance and activation in response to neuroinflammation. Previous studies have shown that Orai1, a key calcium channel, plays a critical role in regulating microglia function. Microglia morphology is directly related to function, typically more ramified in surveillant state and more amoeboid when activated. We hypothesized that the deletion of the Orai1 channel in microglia could alter the morphology of the cells. To address this, our study employed Orai1fl/flCx3CR1-Cre/ERT2 knockout mice (Orai1-KO) for microglia depletion or Orai1fl/fl (control) to investigate how Orai1 influences microglial morphology. Using fluorescent immunohistochemistry targeting Iba1 (a marker for microglia), we visualized microglial morphology in the prefrontal cortex, and performed a FIJI- based skeleton analysis. Regarding the ramification of the cells we observed a decrease in the endpoints per cell in the Orai1-KO, with no changes in process length. We also observed an increase in soma circularity with no changes in soma area. These results suggest that the Orai1- KO microglia are slightly less complex than the control group, which could indicate structural changes possibly due to lack of calcium. Further studies are needed to confirm this. Together, these findings provide insight on Orai1’s role in microglia morphology changes.