Localization of cholesterol, phosphocholine and galactosylceramide in rat cerebellar cortex with imaging TOF-SIMS equipped with a bismuth cluster ion source.

Time-of-flight secondary-ion-mass-spectrometry (TOF-SIMS) was utilized to address the issue of co-localization of cholesterol, phosphocholine and galactosylceramide in rat cerebellar cortex. Rat cerebellum was fixed, freeze-protected by sucrose, frozen and sectioned by cryoultramicrotomy and dried at room temperature. The samples were analyzed in an imaging TOF-SIMS instrument equipped with a Bi(1-7)+-source. The cholesterol signal (m/z 369 and 385) was localized in Purkinje cells and in nuclei of granular layer cells. The phosphocholine headgroup of phosphatidylcholine and sphingomyelin was localized by imaging a specific fragment (m/z 86). This signal was localized in the molecular layer of cerebellar cortex, in Purkinje cells and in parts of the granular layer probably representing the synapse-rich glomeruli. The galactosylceramide was localized by imaging the quasi-molecular ions at m/z 835 and 851, showed a clear colocalization with cholesterol, but also a specific localization in dots (diameter