Direct profiling of lipid distribution in brain tissue using MALDI-TOFMS

Recent developments in mass spectrometry have permitted direct analysis of biomolecules in tissue. However, most studies have focused on proteins with emphasis on biomarker discovery. In the present work, matrix-assisted laser desorption/ionization mass spectrometry was used for the direct analysis of lipids in rat cerebellum. The lipid bilayer role as a storage depot for small organic molecules such as therapeutic drugs and pollutants such as DDT, as well as the ability to compare lipid profiles in healthy and diseased animal models, are a few of the many reasons why the direct probing of tissue to determine the qualitative and possibly quantitative lipid content could be a very useful tool. Molecular ions corresponding to cholesterol, phosphatidylcholines, sphingomyelins, and phosphatidylethanolamines were recorded in positive ion mode, while ones corresponding to phosphatidylinositols, sulfatides, and gangliosides were recorded in negative ion mode. Overall, representatives from all major categories of brain lipids including cholesterol, 15 phospholipid species (9 phosphatidylcholines, 1 sphingomyelin, 3 phosphatidylethanolamines, 2 phosphatidylinositols), 10 sulfatides (5 hydroxylated species and 5 nonhydroxylated species), and 7 species of gangliosides were detected.