Electronmicroscopic immunocytochemistry of pig brain shows that endopeptidase-24.11 is localized in neuronal membranes.

An ultrastructural study of endopeptidase-24.11 in the globus pallidus from the brain of a newborn pig is reported. The antigen was localized by an immunoperoxidase method using an affinity-purified polyclonal antibody in which staining was performed on thick vibratome sections prior to osmication and flat embedding. When areas selected by light microscopy for re-embedding were examined in the electron microscope a minority of the axonal membranes in the fields examined were observed to be immunostained for endopeptidase-24.11. These were unmyelinated fibres and the membrane staining included not only the length of an axon but also some boutons synapsing with dendrites. Positively staining dendritic and glial membranes were not observed. These results support the view that endopeptidase-24.11 may play a role in inactivating some neuropeptides after their release at the synapse.