Abstract

Galactocerebroside (GalC) and its sulfated derivative sulfatide (SUL) are galactosphingolipids abundantly expressed in oligodendrocytes (OLs). Despite their biological importance in OL development and function, attempts to visualize GalC/SUL in tissue sections have met with limited success. This is at least in part because permeabilization of tissue sections with detergents such as Triton X-100 results in significant degradation of GalC/SUL immunoreactivity. Here we establish a novel method that enables visualization of endogenous GalC/SUL in OLs and myelin throughout the entire depth of brain sections. We show that treating brain sections with the cholesterol-specific detergent digitonin instead of Triton X-100 or methanol leads to efficient antibody penetration into tissue sections without disrupting GalC/SUL immunoreactivity. We also determine the optimal concentrations of digitonin using confocal microscopy. With our method, the morphology and the number of GalC/SUL-expressing OLs can be visualized three-dimensionally. Furthermore, our method is applicable to double immunostaining with anti-GalC/SUL antibody and other antibodies which recognize intracellular antigens. Our simple method using digitonin should prove to be useful in enabling detailed examination of GalC/SUL expression in the brain in both physiological and pathological conditions.