Expressions of amyloid precursor protein, synaptophysin and presenilin-1 in the different areas of the developing cerebellum of rat

This study reveals the expressions of Alzheimer's disease-related amyloid p recursor protein, presenilin-1, and a presynaptic marker protein, synaptoph ysin, in the archi-, paleo- and neocerebellum during the postnatal developm ent of the rat. The Western blot results demonstrate a gradual increase in the soluble amyloid precursor protein level in the archicerebellum during t he first 3 weeks, while in the neo- and paleocerebellum the levels reach a plateau as early as the 1st week. Immunohistochemically, the protein is pre sent in the deep part of the external granule cell layer and the internal g ranule cell layer in the newborn animal, while in 3-week-old animals the st aining appears mainly in the perikarya and dendrites of the Purkinje cells. The level of synaptophysin increases progressively from postnatal day 7 up to 3 weeks in the archi- and paleocerebellum, and up to 6 weeks in the neo cerebellum. Immunohistochemically, the amyloid precursor protein staining a ppears first in the inner part of the molecular layer and in the internal g ranule cell layer. In a 3-week-old animal, synaptophysin staining is presen t in all areas of the cerebellar molecular layer and in the internal granul e cell layer. The presenilin-1 immunohistochemical reaction appeared equall y in the archi-, paleo- and neocerebellum. Much of the staining is present in the glial cells and Purkinje cells. Less immunoreactivity is observed in the Golgi cells and granule cells. It is concluded that the postnatal expr essions of soluble and membrane-bound amyloid precursor protein, synaptophy sin and presenilin-1 are regulated differently during the ontogenetical dev elopment of the archi-, paleo- and neocerebellum of rat. Further, the amylo id precursor protein and presenilin-1 may be present in cells which do not degenerate in Alzheimer's disease. (C) 2000 Elsevier Science Ltd. All right s reserved.