TOPOGRAPHICAL DISTRIBUTION OF SYNAPTIC-ASSOCIATED PROTEINS IN THE NEURITIC PLAQUES OF ALZHEIMERS-DISEASE HIPPOCAMPUS

Studies of the molecular composition of the abnormal neuritic processe s of the plaques in Alzheimer's disease (AD) have shown that these str uctures are immunoreactive with antibodies against growth-related mole cules, synaptic/axonal proteins, and cytoskeletal proteins. These stud ies suggest that a subpopulation of abnormal neurites in the plaque ar e sprouting axons that eventually degenerate. To test this hypothesis further we studied the regional distribution of plaques in the hippoca mpus using a panel of monoclonal antibodies against synaptic proteins. With these antibodies we found a greater proportion of immunoreactive plaques compared to previous studies where a monoclonal antibody agai nst synaptophysin was used. The most sensitive antobodies to detect ne uritic plaques were SP11 and anti-p65, and the largest number of posit ive plaques was found in the entorhinal cortex and CA1 region. These r esults further support the theory that synaptic and axonal damage are involved in plaque formation in AD.