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Cell‐type specific organization of glycine receptor clusters in the mammalian spinal cord
Author(s) -
Alvarez Francisco J.,
Dewey Dianne E.,
Harrington Deborah A.,
Fyffe Robert E.W.
Publication year - 1997
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19970303)379:1<150::aid-cne10>3.0.co;2-t
Subject(s) - gephyrin , glycine receptor , postsynaptic potential , inhibitory postsynaptic potential , neuroscience , biology , interneuron , soma , spinal cord , postsynaptic density , renshaw cell , motor neuron , neuron , receptor , excitatory postsynaptic potential , glycine , biochemistry , amino acid
Glycinergic synapses play a major role in shaping the activity of spinal cord neurons. The spatial organization of postsynaptic receptors is likely to determine many functional parameters at these synapses and is probably related to the integrative capabilities of different neurons. In the present study, we have investigated the organization of gephyrin expression along the dendritic membranes of α‐ and γ‐motoneurons, Ia inhibitory interneurons, and Renshaw cells. Gephyrin is a protein responsible for the postsynaptic clustering of glycine receptors, and the features of gephyrin and glycine receptor α 1 ‐subunit immunofluorescent clusters displayed similar characteristics on ventral horn spinal neurons. However, the density of clusters and their topographical organization and architecture varied widely in different neurons and in different dendritic regions. For motoneurons and Ia inhibitory interneurons, cluster size and complexity increased with distance from the soma, perhaps as a mechanism to enhance the influence of distal synapses. Renshaw cells were special in that they displayed an abundant complement of large and morphologically complex clusters concentrated in their somas and proximal dendrites. Serial electron microscopy confirmed that the various immunoreactivity patterns observed with immunofluorescence accurately parallel the variable organization of pre‐ and postsynaptic active zones of glycinergic synapses. Finally, synaptic boutons from single‐labeled axons of glycinergic neurons (Ia inhibitory interneurons) were also associated with postsynaptic receptor clusters of variable shapes and configurations. Our results indicate that mechanisms regulating receptor clustering do so primarily in the context of the postsynaptic neuron identity and localization in the dendritic arbor. J. Comp. Neurol. 379:150‐170, 1997. © 1997 Wiley‐Liss, Inc.