Fig 1: Immunohistochemical staining for reactive glial-fibrillary acidic protein (GFAP+) astrocytes (Alexa-488) around thioflavin S+ Aß plaques (A) and definition of halo and core (B). A plaque was identified by thioflavin S staining under the fluorescence microscope and the plaque core (average diameter 60 µm) and the halo (3× the diameter of the core) are circled. In situ hybridization for PPT-A (C and D) mRNA in an 11-month-old APPSL mouse. The plaques were identified by thioflavin S staining (C). Silver grains of PPT-A mRNA are centered directly above the thioflavin S-stained plaques (D). Scale bar in A = 40 µm. Abbreviations: Aß, ß-amyloid; mRNA, messenger RNA; PPT-A, preprotachykinin-A.