Localization of Lipids and Lipoprotein in Perivascular FGP Cells of Rat Cerebellar Cortex.

Abstract

A type of perivascular cell (fluorescent granular perithelial cell; FGP cell) found around the blood vessels of the rat brain contains granules which show auto-fluorescence in the cytoplasm. In this study, the localization of lipids and low-density lipoprotein (LDL) in these FGP cells was investigated cytochemically and immunocytochemically in order to determine the functions of FGP cells.The cerebellar cortexes of male Wistar rats, aged 8 weeks to 30 months, were used. Triglyceride (TG), phospholipid (PL) and cholesteryl ester (CE) were revealed in FGP cells by using enzymic digestive methods. Endocytotic vesicles containing TG, PL and CE were located inside the FGP cells and were fused with granules. G1, G3, G4 and foamy G5 granules had TG, PL, CE and LDL in and around their membranes. G2 granules, with lower electron density than G1 granules, contained TG, PL, CE and LDL in their heterogeneous matrices. Lipids appeared to occur in granules as a lipoprotein. The results suggest that FGP cells take up TG, PL and CE by endocytosis and internalize them into these granules as components of LDL, playing the role of a scavenger macrophage in the perivascular space of the central nervous system.