Spatial compartmentalization of AMPA glutamate receptor subunits at the calyx of Held synapse.

The mature calyx of Held ending on principal neurons of the medial nucleus of the trapezoid body (MNTB) has very specialized morphological and molecular features that make it possible to transmit auditory signals with high fidelity. In a previous work we described an increased localization of the ionotropic alpha-amino-3-hydroxy-5-methyl-4 isoxazolepropionic acid (AMPA) glutamate receptor (GluA) subunits at postsynaptic sites of the calyx of Held-principal cell body synapses from postnatal development to adult. The aim of the present study was to investigate whether the pattern of the synaptic distribution of GluA2/3/4c and -4 in adult MNTB principal cell bodies correlated with preferential subcellular domains (stalks and swellings) of the calyx.

Developmental increase in postsynaptic alpha-amino-3-hydroxy-5-methyl-4 isoxazolepropionic acid receptor compartmentalization at the calyx of Held synapse.

The pattern of expression of ionotropic glutamate receptor (GluR) subunits 1-4 in the medial nucleus of the trapezoid body (MNTB) has been reported to change during development. The aim of this study was to compare the distribution of the GluR1-4 subunits in the MNTB at postnatal day (P) 9, before high-frequency signal transmission in the auditory system has developed, with that observed in mature adult rats. GluR1-4 subunits were studied by preembedding and postembedding immunocytochemical methods.