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Three classes of inhibitory amino acid terminals in the cochlear nucleus of the guinea pig
Author(s) -
Juiz Jose M.,
Helfert Robert H.,
Bonneau Joann M.,
Wenthold Robert J.,
Altschuler Richard A.
Publication year - 1996
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(19960909)373:1<11::aid-cne2>3.0.co;2-g
Subject(s) - dorsal cochlear nucleus , inhibitory postsynaptic potential , glycine , biology , free nerve ending , glycine receptor , postsynaptic potential , immunolabeling , nucleus , synaptic vesicle , guinea pig , immunocytochemistry , cochlear nucleus , neuroscience , biophysics , vesicle , amino acid , microbiology and biotechnology , anatomy , biochemistry , endocrinology , immunohistochemistry , receptor , membrane , immunology
Electron microscopic postembedding immunocytochemistry was used to analyze and assess the synaptic distribution of glycine (GLY) and γ‐amino butyric acid (GABA) immunoreactivities in the guinea pig cochlear nucleus (CN). Three classes of endings were identified containing immunolabeling for glycine, GABA, or both glycine and GABA (GLY/GABA). All classes were similar in that the terminals contained pleomorphic vesicles and formed symmetric synapses with their postsynaptic targets. A fourth class, which labeled with neither antibody, contained round vesicles and formed asymmetric synapses. Glycine endings predominated in the ventral CN, while GLY/GABA endings were prevalent in the dorsal CN. GABA endings were the least common and smallest in size. Glycine, GLY/GABA, and GABA endings differed in their proportions and patterns of distribution on the different classes of projection neurons in the CN, including spherical bushy, type I stellate/multipolar, and octopus cells in the ventral CN and fusiform cells in the dorsal CN. The vast majority of anatomically‐defined, putative inhibitory endings contain GLY, GABA, or both, suggesting that most of the inhibition in the cochlear nucleus is mediated by these three cytochemically and, probably, functionally distinct classes of endings. The results of this study also suggest that a large proportion of the GABA available for inhibition in the CN coexists in terminals with glycine. © 1996 Wiley‐Liss, Inc.