Fig. 6: FABP5 demarcates dying neurons in cortical and hippocampal sections with hypoxic damage.

A 15 h post-transient middle cerebral artery occlusion in mouse show evidence of ferroptosis by FABP5 staining. Left image: hematoxylin/eosin stain at the level of basal ganglia. The area of the lesion is bordered by stippled line. The red box marks an area of the penumbra, the black box an area of the corresponding healthy contralateral side. The images on the right show examples of the immunohistochemical detection of FABP5 in proximal areas. Arrows in the penumbra indicate almost exclusively neurons with partly shrunken nuclei and cytoplasmic FABP5 expression, while contralateral side neurons are healthy and unstained (open arrows). Scale bars correspond to 800 µm (left) and 20 µm (right images), respectively. B Human cerebellar cortex of a control case (C04) and a case with hypoxic damage (H04). (Left) Hematoxylin/eosin stains. In contrast to intact Purkinje cells (PCs; open arrows), hypoxically damaged PCs (solid arrows) are shrunken with eosinophilic cytoplasm, condensed nuclei, and an undefined nucleolus. (Right) Immunohistochemistry for FABP5 in neighboring sections, only hypoxically damaged PCs express FABP5 (solid arrows) in contrast to intact PCs (open arrows). Scale bar corresponds to 20 µm. C Human hippocampus of a control case (C01) and a case with hypoxic damage (H01). (Left) Hematoxylin/eosin stains. Hypoxically damaged shrunken pyramidal cells with condensed nuclei and eosinophilic cytoplasm (arrows). (Right) FABP5 immunohistochemistry in adjacent sections. In hypoxic damage almost all pyramidal cells strongly express FABP5 (arrows) in contrast to the control case without FABP5 expression. The weak brown color in the control case corresponds to lipofuscin. Scale bar corresponds to 20 µm.