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Distribution of GABA, glycine, and glutamate immunoreactivities in the vestibular nuclear complex of the frog
Author(s) -
Reichenberger I.,
Straka H.,
Ottersen O.P.,
Streit P.,
Gerrits N.M.,
Dieringer N.
Publication year - 1997
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(19970113)377:2<149::aid-cne1>3.0.co;2-3
Subject(s) - colocalization , glycine , glutamate receptor , vestibular nuclei , vestibular system , biology , glycine receptor , inhibitory postsynaptic potential , amino acid , biophysics , neuroscience , anatomy , chemistry , microbiology and biotechnology , biochemistry , receptor
This study describes the localization of γ‐aminobutyric acid (GABA), glycine, and glutamate immunoreactive neurons, fibers, and terminal‐like structures in the vestibular nuclear complex (VNC) of the frog by using a postembedding procedure with consecutive semithin sections at the light microscopic level. For purposes of this study, the VNC was divided into a medial and a lateral region. Immunoreactive cells were observed in all parts of the VNC. GABA‐positive neurons, generally small in size, were predominantly located in the medial part of the VNC. Glycine‐positive cells, more heterogeneous in size than GABA‐positive cells, were scattered throughout the VNC. A quantitative analysis of the spatial distribution of GABA or glycine immunoreactive cells revealed a complementatory relation between the density of GABA and glycine immunoreactive neurons along the rostrocaudal extent of the VNC. In about 10% of the immunolabeled neurons, GABA and glycine were colocalized. Almost all vestibular neurons were, to a variable degree, glutamate immunoreactive, and colocalization of glutamate with GABA and/or glycine was typical. GABA, glycine, or glutamate immunoreactive puncta were found in close contact to somata and main dendrites of vestibular neurons. A quantitative analysis revealed a predominance of glutamate‐positive terminal‐like structures compared to glycine or GABA containing profiles. A small proportion of terminal‐like structures expressed colocalization of GABA and glycine or glycine and glutamate. The results are compared with data from mammals and discussed in relation to vestibulo‐ocular and vestibulo‐spinal projection neurons, and vestibular interneurons. GABA and glycine are the major inhibitory transmitters of these neurons in frogs as well as in mammals. The differential distribution of GABA and glycine might reflect a compartmentalization of neurons that is preserved to some extent from the early embryogenetic segmentation of the hindbrain. J. Comp. Neurol. 377:149–164, 1997. © 1997 Wiley‐Liss, Inc.