抄録
We previously showed that, in cultured rat hippocampal slices, repetitive induction of LTP (Long-Term Potentiation) by exposure to glutamate at 24 h intervals produced a long-lasting enhancement in synaptic strength accompanied by synaptogenesis. We call this phenomenon RISE to discriminate it from conventional single LTP. During the development of RISE, the component of Ca2+-permeable AMPA receptor (CP-AMPAR) in population EPSP increased transiently and the gene/protein expression of GluR1 subunit of AMPAR was enhanced in the corresponding period. Immunohistochemical analysis also showed an increase in the number of GluR1-immunopositive puncta. Therefore, it is suggested that the transiently expressed GluR1 subunit would be distributed preferentially to the newly produced synapses, forming CP-AMPAR composed of GluR1 subunit. In the present study, we examined the distribution of GluR1 during and after RISE establishment using immunoelectron microscopic technique, focusing especially on the location of GluR1 immunoreactivity and its spatial relationship to presynaptic structure. In preliminary examinations, GluR1 immunoreactivity increased predominantly in the denderitic shafts rather than in the dendritic spines in the early phase of RISE development. [J Physiol Sci. 2008;58 Suppl:S135]
