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Differential expression of the metabotropic glutamate receptor mGluR1α by neurons and axons in the cochlear nucleus: In situ hybridization and immunohistochemistry
Author(s) -
Bilak Stephan R.,
Morest D. Kent
Publication year - 1998
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/(sici)1098-2396(199804)28:4<251::aid-syn1>3.0.co;2-8
Subject(s) - dorsal cochlear nucleus , cochlear nucleus , metabotropic glutamate receptor , parallel fiber , granule cell , neuroscience , metabotropic receptor , biology , microbiology and biotechnology , nucleus , glutamate receptor , inhibitory postsynaptic potential , chemistry , excitatory postsynaptic potential , receptor , hippocampal formation , dentate gyrus , biochemistry
mGluR1α is a metabotropic glutamate receptor involved in synaptic modifiability. A differential expression in specific neuronal types could reflect their different connections and response properties in central auditory processing. Using in situ hybridization and immunohistochemistry, we studied mGluR1α receptor expression throughout the cochlear nucleus. Robust labeling occurred in the dorsal cochlear nucleus and small cell shell, with less in the ventral cochlear nucleus. Among the most intensely labeled were the granule cells of the small cell shell. In the dorsal cochlear nucleus, most cell types expressed message and receptor protein, except granule cells. High levels of receptor were expressed by corn cells and cartwheel cells. The terminal dendrites and synaptic spines of cartwheel and fusiform cells contained receptor protein in the molecular layer, where they could synapse with parallel fibers. Fusiform dendrites also expressed mRNA for mGluR1α. The basal dendrites of fusiform cells contained receptor protein in the region where they receive cochlear nerve synapses. Immunostaining of terminal axons was prominent in the molecular layer and the small cell shell, where they were associated with synaptic nests, structures thought to provide long‐term changes in excitability. Differential expression levels may reflect different functional requirements of specific cell types, including inhibitory interneurons, like corn cells and cartwheel cells, and excitatory interneurons, like granule cells in the small cell shell, which may participate in local circuits involved in modulatory or gating functions, such as stimulus enhancement or suppression. In presynaptic axons, mGluR1α may relate to the long‐term signaling requirements of their modulatory functions. Synapse 28:251–270, 1998. © 1998 Wiley‐Liss, Inc.