AGE-RELATED CONGOPHILIC INCLUSIONS IN THE BRAINS OF APOLIPOPROTEIN E-DEFICIENT MICE

The hippocampal region of apolipoprotein E-deficient mice of varying a ges was examined for any morphological changes by light and electron m icroscopy. Unusual periodic acid-Schiff-positive granules were seen in the hippocampal area of these animals as early as the fourth week of life and their numbers increased gradually with age. These granules we re never found in control C57BL/6J (B6) mice before six months-of-age and their numbers were invariably low. They were strongly congophilic when stained with a modified Congo Red technique and reacted with a mo noclonal antibody specific to amino acids 17-24 and 3543 of the beta-a myloid peptide. The immunostaining of these granules with the beta-amy loid peptide was lost after specific adsorption with the appropriate s ynthetic peptide. These granules were identified ultrastructurally as non-membrane-bound fibrillogranular material in the cytoplasm of proto plasmic astrocytes. The data indicate that an amyloid-like protein acc umulates in the protoplasmic astrocytes of the hippocampus of apolipop rotein E-deficient mice, especially in the brains of old animals. (C) 1997 IBRO. Published by Elsevier Science Ltd.