Delayed appearance of the scaffolding proteins PSD-95 and homer-1 at the developing rat calyx of held synapse

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 postsynap...

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Bibliographic Details
Published in:Journal of comparative neurology (1911) 2010-11, Vol.518 (22), p.4581-4590
Main Authors: Soria Van Hoeve, John S., Borst, J. Gerard G.
Format: Article
Language:English
Subjects:
active zone
Animals
Animals, Newborn
auditory brainstem
Brain Stem - cytology
Brain Stem - growth & development
Carrier Proteins - metabolism
colocalization
confocal microscopy
Disks Large Homolog 4 Protein
Gene Expression Regulation, Developmental - physiology
Homer Scaffolding Proteins
Intracellular Signaling Peptides and Proteins - metabolism
Membrane Proteins - metabolism
Neurons - cytology
postsynaptic density
Rats
Rats, Wistar
Synapses - metabolism
Vesicular Glutamate Transport Protein 1 - metabolism
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Summary: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.
ISSN:0021-9967
1096-9861
1096-9861
DOI:10.1002/cne.22479