Expression of neuropsin in oligodendrocytes after injury to the CNS

Proteases are involved in a variety of processes including demyelination af ter injury to the central nervous systyem. Neuropsin is a serine protease. which is constitutively expressed in the neurons of the limbic system. In t he present study. intrahippocampal kainate injection and enucleation were p erformed on adult mice. Neuropsin mRNA and protein expression was detected by in situ hybridization and immunohistochemistry. Double in situ hybridiza tion confirmed that the mRNA expression was induced in oligodendrocytes. On e day after kainate injection to the hippocampus, neuropsin mRNA was expres sed. peaking 4-8 days postoperatively and disappearing at 14 days. Immunohi stochemistry and immunoelectron microscopy revealed that neuropsin was expr essed in the cell body of oligodendrocytes and myelin. To see if neuropsin degrades myelin protein, purified myelin was incubated with recombinant neu ropsin. A decrease in the intensity of the bands of myelin basic protein wa s observed. These results indicate that neuropsin is involved in demyelinat ion. (C) 2001 Elsevier Science Ireland Ltd and the Japan Neuroscience Socie ty. All rights reserved.