Bilateral common carotid artery ligation transiently changes brain lipid metabolism in rats

Brain lipid metabolism was studied in rats following permanent bilateral common carotid artery ligation (BCCL), a model for chronic cerebral hypoperfusion. Unesterified (free) fatty acids (uFA) and acyl-CoA concentrations were measured 6 h, 24 h, and 7 days after BCCL or sham surgery, in high energy-microwaved brain. In BCCL compared to sham rats, cytosolic phospholipase A2 (cPLA2) immunoreactivity in piriform cortex, and concentrations of total uFA and arachidonoyl-CoA, an intermediate for arachidonic acid reincorporation into phospholipids, were increased only at 6 h. At 24 h, immunoreactivity for secretory phospholipase A2 (sPLA2), which may regulate blood flow, was increased near cortical and hippocampal blood vessels. BCCL did not affect levels of brain IB4+ microglia, glial fibrillary acidic protein (GFAP) astrocytes, cyclooxygenase-2 (COX-2) immunoreactivity at any time, but increased cPLA2 immunoreactivity in one region at 6 h. Thus, BCCL affected brain lipid metabolism transiently, likely because of compensatory sPLA2-mediated vasodilation, without producing evidence of neuroinflammation.