ARG1 and Alzheimer disease: Tukey’s post hoc revealed that IL-4 injection significantly increased the number of arginase-1 positive cells in the striatum and hippocampus of 3xTg AD when compared to the number of arginase-1 positive cells in the same regions in the non-transgenic (P < 0.0001) and all groups with saline injection (P < 0.0001).