Electron microscopic localization of Nogo-A at the postsynaptic active zone of the rat.

Our previous study has demonstrated intraneuronal localization of Nogo-A in motoneurons of the adult rat spinal cord. In the present study, we wished to explore Nogo-A immunoreactivity at synapses using pre-embedding and post-embedding immunogold cytochemistry. Immunogold particles for Nogo-A could be identified in dendrites of the spinal cord motoneurons. Some Nogo-A immunogold particles were found in close apposition to the postsynaptic density and the postsynaptic dense bodies at both symmetric and asymmetric synapses. The present finding of Nogo-A at the postsynaptic active zone provides a morphological basis for the possibility that the Nogo-A-Nogo receptor system may contribute to structural plasticity at synapses as well as along the axonal pathway.