抄録
Dendritic spines, which are functional round-shape postsynaptic units of most excitatory synapses, are organized by glutamate receptors, actin-cytoskeletal proteins and postsynaptic density (PSD) scaffold proteins. Further, spines represent the activity-dependently pleomorphic structures based on actin cytoskeleton. We previously demonstrated that spine morphogenesis in neuronal development requires synaptic clustering of actin components and the following synaptic clustering of PSD proteins in dendritic filopodia, which are precursors of spines. (J. Neurosci.23(16):6586-95. Takahashi et. al.) However, it is unknown how synaptic activity regulates synaptic clustering of these postsynaptic molecules in neuronal development. In this study, we investigate how AMPA receptor (AMPAR) and NMDA receptor (NMDAR) activities regulate synaptic clustering of filamentous actin (F-actin) and drebrin during development. Chronic blockage of AMPAR activity inhibits their synaptic clustering, and also inhibits the morphological spine maturation from filopodia. In contrast, chronic blockage of NMDAR activity slightly promotes their clustering and the spine maturation. Our data suggest that AMPAR and NMDAR activities bidirectionally regulate the postsynaptic actin organization in developing dendritic spines. [Jpn J Physiol 54 Suppl:S149 (2004)]
