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 immunostaining for GAP-43 we found that 3 months after KA treatment, several GAP-43 positive terminals in the IML showed structural characteristics of messy fibre boutons. No GAP-43-positive mossy fibre terminals were found in the normal projection areas of granule cells, thus indicating that newly synthesized GAP-43 is transported predominantly in the axonal branches actively undergoing remodelling. These results provide evidence of the involvement of GAP-43 in the structural remodelling of messy fibres, and suggest a role of this protein in the functional activity of the sprouted messy fibres as a consequence of KA-induced seizures.