Département de chimie moléculaire

The present study aimed to examine whether positron emission tomog. (PET) could evaluate cerebral angiogenesis. Mice were housed in a hypoxic chamber with 8-9{%} oxygen for 4, 7, and 14 days, and the angiogenic responses were evaluated with a radiotracer, 64Cu-cyclam-RAFT-c(-RGDfK-)4, which targeted $\alpha$V$\beta$3 integrin and was imaged with PET. The PET imaging results showed little uptake during all of the hypoxic periods. Immunofluorescence staining of the $\beta$3 integrin, CD61, revealed weak expression, while the microvessel d. assessed by CD31 staining increased with the hypoxic duration. These observations suggest that the increased vascular d. originated from other types of vascular remodeling, unlike angiogenic sprouting. We then searched for any signs of vascular remodeling that could be detected using PET. PET imaging of 11C-PK11195, a marker of the 18-kDa translocator protein (TSPO), revealed a transient increase at day 4 of hypoxia. Because the immunofluorescence of glial markers showed unchanged staining over the early phase of hypoxia, the obsd. upregulation of TSPO expression probably originated from non-glial cells (e.g. vascular cells). In conclusion, a transient increase in TSPO probe uptake was detected with PET at only the early phase of hypoxia, which indicates an early sign of vascular remodeling induced by hypoxia. [on SciFinder(R)]