Regional Phospholipid Profile of Alzheimer’s Brain

Abstract

The phospholipids constitute the major component of brain lipids accounting for greater than 60% of total brain lipids. Most of the brain phospholipids are associated with the membrane system (1,2). Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), sphingomyelin (SM), and ethanolamine plasmalogen (EP) are the six main brain membrane phospholipids. The relative ratio of these six phospholipids (phospholipid profile) is known to exhibit regional specificity (1-4). Gray matter is especially rich in PC, while in white matter the proportion of PE is increased. While PS and PI are distributed throughout the brain in relatively even proportions, SM and EP reflect myelin rich structures. The phospholipid profile of the various regions of the brain are remarkably consistent and alterations in the profile reflect abnormalities in the membrane system. In this study, we investigated regional membrane phospholipid profiles of four major cortical areas (frontal, parietal, temporal, and occipital) in four cases of autopsy proven Alzheimer’s disease using phosphorus-31 (³¹P) nuclear magnetic resonance (NMR) spectroscopy and acidified lipid extraction of brains (3). Proton NMR spectroscopy was also performed to investigate the relative levels of unsaturated fatty acids.