Changes in CNS myelin proteins and glycoproteins after in situ autolysis

Abstract

The effects of postmortem autolysis in situ on myelin proteins and glycoproteins were studied in 25- and 125-day-old mouse brain and in adult bovine brainstem. In bovine myelin a loss of the major myelin glycoprotein was the only difference observed when the tissue was left at 19 degrees C for 24 hours compared to immediately frozen material. In the autolysed mouse brain, the myelin major glycoprotein was the most affected component with a 55% decrease. Both myelin basic protein components were degraded with a 35% loss. The other myelin proteins did not change under the conditions used for this study. There was also no change in the specific activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase, a myelin-associated enzyme. Using the double labelling technique with [3H]fucose and [3 5S] sulfate as precursors injected intracranially, a shift of the major myelin glycoprotein labelled with radioactive sulfate towards a smaller apparent molecular size was observed as a result of the autolysis whereas the electrophoretic mobility of the fucose labelled major peak was unaffected.