activated microglia undergo morphological changes from a “ramified” state, a highly branched and elongated appearance, to an “amoeboid” state, with retracted processes and a more rounded shape (50), we used “fractal analysis” in ImageJ at the single-cell level to evaluate human microglial morphology (Fig. 3C and fig. S4B). In the absence of ethanol, high-PRS microglial cells displayed lower fractal dimension values and higher circularity compared to low-PRS microglial cells (Fig. 3D and fig. S4, C to E). Following ethanol exposure, there was a reduction in fractal dimension observed in both high-PRS and low-PRS microglial cells (Fig. 3D), indicating a decrease in the complexity of microglial morphology in response to ethanol exposure. Notably, high-PRS microglial cells exhibited a more significant decrease in fractal dimension and spine ratio, alongside a marked increase in circularity relative to their low-PRS counterparts after exposure to ethanol. These observed differences were notably more substantial under the 75 mM ethanol condition (Fig. 3D). These data indicated that human microglial cells were activated by ethanol exposure, and there are differences in morphological features between high-PRS and low-PRS microglial cells, suggesting that genetic background may affect cellular responses to ethanol.
