A Pair of Indicators for Characterizing Cerebral Microbleeds Based on Raman Spectrum and Two-Photon Imaging.

Cerebral microbleeds (CMBs) lead to cognitive decline, linked to the axonal structure composed of phospholipid bilayers. Current methods are difficult to obtain in situ changes of biochemical component concentration during CMB. In this study, by Raman spectrum and two-photon imaging, we achieve in situ changes in the information of biochemical components concentration during CMB. The overall concentration of phospholipids in the damaged tissue significantly decreases after CMB, forming a large region of low concentration, but the relative concentration of phosphatidylinositol (PI) increases, reflecting the inhibition role of the phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) pathway. Accordingly, two-photon images of neurons show a clear decrease in the number of axons, indicating a close correlation between phospholipid hydrolysis and axon damage, as well as cognitive impairment. Therefore, the decrease in phospholipid concentration and the increase in the PI concentration might serve as a pair of indicators for characterizing CMB and its relationship with cognitive decline.