CEREBRAL AMYLOID ANGIOPATHY AND PLAQUES, AND VISCERAL AMYLOIDOSIS IN AGED MACAQUES

In the present study, we report our extended data on the incidence of two types of cerebral amyloidosis (plaques and plaques associated with angiopathy) and visceral amyloidosis in late adult and aged captive r hesus monkeys (Macaca mulatta). In a total of 81 brains from animals r anging from 16 to 39 years old, beta-amyloid plaques were found in 38, 10 of which were associated with amyloid angiopathy. Brains from eigh t adults, 16 to 19 years, had no lesions. In aged groups, the rates we re 20.8% in the 20- to 25-year group (24), 60.9% in the 26- to 31-year group (41), and 100% in the 33- to 39-year group (8). Twelve monkeys in these aged groups had an involvement of amyloidosis in either the l iver, the adrenal, or the pancreatic islets: and 7 of 12 had amyloid p laques (5) and plaques associated with cerebral angiopathy (2). No neu rofibrillary tangles were detected in these brain lesions. Amyloid in both plaques and cerebral angiopathy showed immunocytochemical crossre activity with human amyloid beta (beta/A4) and precursor proteins (APP -A4), but visceral amyloid was negative. Ultrastructurally, amyloid in itially appears as loose filaments in the perivascular or Disse space: and they further aggregate to produce dense interlacing bundles. Cere bral amyloid angiopathy associated with plaque appears to be a subclas s of senile plaque lesions in aged monkeys as well as in aged humans, and it appears to have no pathogenetic correlation with visceral amylo idosis.