Differential distribution of amyloid protein precursor immunoreactivity in the rat brain studied by using five different antibodies

Abstract

The β‐amyloid or A4 protein is found deposited in neuritic plaques and neurofibrillary tangles in Alzheimer's disease (AD) affected brains and in the brains of adults with Down's Syndrome. The precursor to this 42 amino acid protein is the 695 amino acid long amyloid protein precursor (APP‐695). Two additional APP species, APP‐751 and APP‐770, each contain a 56‐amino‐acid insert sequence that is analogous to Kunitz protease inhibitors. APP mRNA is widely distributed in both the human and rat brain, although the adult rat does not develop mature amyloid pathology. In this study we used antibodies against the N‐terminus, junction site (unique to APP‐695) insert sequence (unique to APP‐751,‐770..