Immunochemical characterization of synaptosomal membrane antigens from chicken brain : Histochemical localization in the day-old chick.

A set of synaptic membrane antigens has been investigated in a number of tissues by indirect immunofluorescence histochemistry, using an antiserum (SPM-I) raised against a purified synaptosomal plasma membrane fraction prepared from day-old chick forebrain. The antigens were found to be present in both the central and peripheral nervous systems and none of them were restricted to the forebrain. The antigens were not detectable in nonneural tissues except for the adrenal medulla. Since the antigens could not be detected in a number of clearly defined glial cell populations or a surgically induced gliosis of the optic nerve, the antigens appear to be nerve specific. The antigens were not present in all types of neurons, thus indicating that surface membrane differences exist between different classes of neurons. Within the plasma membrane of the nerve cell the antigens were not uniformly distributed: they were present in the synaptic region and, in some nerve cells, also in axonal region but were absent from perikaryal membranes and extended regions of dendritic membranes. In the sciatic nerve the antigens were transported at the fast rate of anterograde axonal transport as well as in the retrograde direction. These results have been compared with previous attempts to detect nerve-specific membrane components by immunological means.