Pathological changes in Alzheimer's brain evaluated with fluorescence emission analysis (FEA)

摘要

Development of AD is associated with cerebrovascular deposition of amyloid beta (AP) as well as a progressive increase in vascular collagen content. Both Aβ and collagen are naturally fluorescent compounds when exposed to UV light. We analyzed autofluorescence emitted from brain tissue samples and isolated brain resistance vessels harvested postmortem from patients with Alzheimer's disease (AD) and age-matched controls. Fluorescence emission, excited at 355 nm with an Nd: YAG laser, was measured using a fiber-optic based fluorescence spectroscopic system for tissue analysis. Significantly higher values of fluorescence emission intensity (P<0.001) in the spectral region from 465 to 490 nm were detected in brain resistance vessel samples from AD patients compared to the normal individuals. Results from western blot analysis showed elevated levels of type Ⅰ and type Ⅲ collagen, and reduced levels of type Ⅳ collagen in resistance vessels from AD patients, compared to control samples. In addition, using direct scanning of the cortical surface for fluorescence emission by the laser-induced fluorescence spectroscopy system we detected a significantly (P<0.05) higher level of apoptosis in AD brain tissue compared to age-matched controls. Fluorescence emission analysis (FEA) appears to be a sensitive technique for detecting structural changes in AD brain tissue.