Delayed behavioral recovery and impaired cholinergic sprouting in lesioned male APOE4 mice. A, During the Barnes maze probe trial, lesioned APOE4 mice were impaired at 30 and 70 dpl, whereas lesioned APOE3 mice were only mildly affected at 30 dpl. $Distance in target quadrant differs from chance level (p < 0.05; t test); ¤differs from target quadrant (p < 0.05; Fisher's LSD). B, Top, Lesioned APOE4 mice (red) showed a broader glutamatergic loss at 30 dpl and a delayed glutamatergic reinnervation at 70 dpl. Only lesioned APOE3 mice (blue) displayed a cholinergic sprouting at 30 and 70 dpl. The presumed main origin of VGLuT1-positive inputs is indicated in orange above the corresponding hippocampal layer in black. *VAChT density differs from sham level (p < 0.05, Fisher's LSD); #VGLuT1 immunoreactivity differs from sham level (p < 0.05, Fisher's LSD). Bottom, Examples of VGLUT1 (green) and VAChT stainings (red) taken from the molecular layer of the DG. Scale bar, 50 μm.