Changes of free cholesterol and neutral lipids after transient focal brain ischemia in rats

We investigated temporal and spatial changes of free cholesterol (FC) and neutral lipids (NLs) after brain ischemia with filipin complex staining to detect mainly FC and Nile Red staining for NLs such as cholesteryl ester (CE) and triacylglyceride (TAG). Filipin stainining decreased during 1 to 7 d and lost at 21 d after transient middle cerebral artery (MCA) occlusion in the ischemic core, but did not change in the penumbra. Nile Red positive droplets reached the maximum at 7 d after transient MCA occlusion (MCAO) and gradually decreased in the core, while the peak time delayed in the penumbra. Most Nile Red positive droplets were double positive for ED1 in the core, and were localized within GFAP positive cells in the penumbra. The present study suggests that changes of FC and NLs are different temporally and spatially between the ischemic core and the penumbra in relation to degenerative and regenerative neural processes following brain ischemia. Macrophages and astrocytes are presumed to play important roles in lipid metabolism for neural reorganization of the ischemic brain injury in the ischemic core and the penumbra, respectively.