ULTRASTRUCTURAL IMMUNOLOCALIZATION OF GAP-43 IN THE SPROUTED MOSSY FIBERS OF KAINIC ACID LESIONED RATS

KAINIC acid (KA)-induced seizures in adult rats have been reported to cause sprouting of messy fibres in the inner molecular layer (IML) of the dentate gyrus. In the present study, using electron microscopic im munostaining for GAP-43 we found that 3 months after KA treatment, sev eral GAP-43 positive terminals in the IML showed structural characteri stics of messy fibre boutons. No GAP-43-positive mossy fibre terminals were found in the normal projection areas of granule cells, thus indi cating that newly synthesized GAP-43 is transported predominantly in t he axonal branches actively undergoing remodelling. These results prov ide evidence of the involvement of GAP-43 in the structural remodellin g of messy fibres, and suggest a role of this protein in the functiona l activity of the sprouted messy fibres as a consequence of KA-induced seizures.