AMYLOID-BETA-1-42 DEPOSITS DO NOT LEAD TO ALZHEIMERS NEURITIC PLAQUESIN AGED DOGS

In Alzheimer's disease, amyloid beta (A beta) is deposited in senile p laques and amyloid angiopathy. Longer A beta peptides, which extend to residue 42 (A beta 42), have been suggested to be critical for the se eding of amyloid. Aged dogs develop cerebral vessel amyloid and parenc hymal preamyloid lesions. Preamyloid in humans is related to senile pl aques, whereas in dogs such progression is rare. We evaluated the comp osition of aged canine vessel amyloid and preamyloid both biochemicall y and immunohistochemically. The vessel amyloid extended mainly to res idue 40 (A beta 40), while preamyloid contained a mixture of A beta 17 -42 and A beta 42, with minimal A beta 40. Our results suggest other f actors besides A beta 42 are important for neuritic plaque formation.