Fig. 2

MAO-B immunohistochemistry in thin sections from hippocampus CA1 and entorhinal cortex regions of Cntr and AD brains. a Hippocampus CA1 images taken at 20× magnification are shown from a Cntr case (left panel) and an AD case (right panel). Note a neuronal loss in AD and intensive staining in the remaining neurons, including fibers, and astrocyte-like cells. Examples of pyramidal neurons are marked by red arrows. Scale bar, 50 μm. b Images of CA1 regions with many pyramidal neurons taken at 40× magnification in a Cntr (left panel) and AD (right panel) brain. Note a bigger variability in the pyramidal neuron staining of AD case while neurons in the control case are more evenly stained. Red arrows point at examples of pyramidal neurons. Scale bar, 50 μm. c Entorhinal cortex, layer II image taken at 20× magnification from a Cntr (left panel) and AD (right panel) brain. Zoomed inset in the left panel shows axonal staining. Note an island-like neuronal staining in the control case that is diminished and replaced by astrocyte-like staining due to the neuronal loss and advanced neurodegeneration in AD. Scale bar, 50 μm. d Immunocytochemistry in mouse primary hippocampal neurons shows axonal, dendritic and somal locations of MAO-B. The neurons were stained for Phalloidin to visualize F-actin and the neuronal structure (white), DAPI to visualize nuclei (blue), Tau-1 to visualize axons (green) and MAO-B (red). Red zoomed inset shows MAO-B staining in a thick (apical) dendrite. Blue zoomed inset shows MAO-B staining in a narrower dendrite. Green zoomed inset shows MAO-B staining in an axon. Images were taken with a Nikon A1RSi point scanning confocal with a 60× oil immersion objective. Scale bar, 10 μm. The axonal image is the sum of a z-stack whereas all other images are single planes. AD Alzheimer disease (Color figure online)