Naturally occurring and experimentally induced beta-amyloid deposits in the brains of marmosets (Callithrix jacchus)

Cerebral beta-amyloid occurs in elderly animals of some species and in Alzh eimer's disease. Previously, we injected 3 young marmosets intracerebrally with brain tissue from a patient with Alzheimer's disease. Six years later, when the monkeys were middle aged, we found moderate numbers of intracereb ral plaques and cerebrovascular deposits containing beta-amyloid. We have r e-examined these brains and those of 10 other marmosets injected with brain homogenate containing beta-amyloid, and have found some beta-amyloid in an imals injected more than 4 years previously. We have found beta-amyloid in 4 of 26 elderly control marmosets, but not in 9 young to middle-aged contro l marmosets. The beta-amyloid found in middle aged marmosets injected with Alzheimer brain tissue was, therefore, not a consequence of their age. Depo sits in large cerebral vessels in elderly marmosets, and in marmosets previ ously injected with brain tissue containing beta-amyloid, reacted with anti bodies to A beta and A beta 1-40; plaques and microvessel deposits reacted with antibodies to A beta and A beta 1-42.