Increase in postsynaptic density material in optic target neurons of the rat suprachiasmatic nucleus after bilateral enucleation.

During and after degeneration of the optic nerve afferents in the rat suprachiasmatic nucleus (SCN) postsynaptic density (PD) material is added to existing symmetrical and asymmetrical appositions of non-optic synapses on optic target neurons. If the correlation between thickness of the postsynaptic density and excitatory or inhibitory function of a synapse holds in this nucleus, the change in morphology of synapses could mean that some inhibitory synapses turn into excitatory contacts.