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Delayed appearance of the scaffolding proteins PSD‐95 and homer‐1 at the developing rat calyx of held synapse
Author(s) -
Soria Van Hoeve John S.,
Borst J. Gerard G.
Publication year - 2010
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/cne.22479
Subject(s) - calyx , postsynaptic potential , synapse , biology , postsynaptic density , trapezoid body , neuroscience , active zone , brainstem , neurotransmission , excitatory postsynaptic potential , anatomy , inhibitory postsynaptic potential , synaptic vesicle , genetics , vesicle , receptor , membrane
The calyx of Held synapse is a giant axosomatic synapse that acts as a fast relay in the sound localization circuit of the brainstem. In rodents it forms within a relatively brief period starting around the second postnatal day (P2). The relative timing of the formation of its pre‐ and the postsynaptic compartment are not yet known. By means of fluorescent immunohistochemistry in neonatal rats we therefore compared the developmental expression patterns of the vesicular glutamate transporter (VGLUT)‐1 and the postsynaptic density scaffolding proteins Homer‐1 and PSD‐95 in the medial nucleus of the trapezoid body (MNTB). Before its formation, colocalized punctate staining of VGLUT‐1 and Homer‐1 or PSD‐95 was observed on principal neurons, in agreement with earlier work showing that they are already innervated by fibers from the cochlear nucleus before the calyx forms. The expression of VGLUT‐1 clusters within the nascent calyx of Held synapse preceded the expression of Homer‐1 and PSD‐95 clusters, as indicated by the presence of principal neurons with only a large contiguous cluster (LCC) of VGLUT‐1 at P2‐3, whereas no neurons with only an LCC for Homer‐1 or PSD‐95 were seen. At P3 the first principal neurons with both a pre‐ and a postsynaptic LCC were observed, and at P12 all principal neurons had both a pre‐ and a postsynaptic LCC. The relatively late appearance of Homer‐1 and PSD‐95 within the developing calyx of Held synapse suggests that they play a role in its stabilization and the recruitment of additional receptors to its postsynaptic density. J. Comp. Neurol. 518:4581–4590, 2010. © 2010 Wiley‐Liss, Inc.