Immunocytochemical localization of glycine in a subset of cartwheel cells of the dorsal cochlear nucleus in rats.
Glycine is an inhibitory neurotransmitter and a glutamate cofactor for N-methyl-D-aspartate (NMDA) receptors in the central nervous system. The distribution of glycine in the auditory system will therefore provide clues as to synaptic mechanisms underlying auditory signal processing. Previous studies have reported the immunocytochemical presence of glycine in the dorsal cochlear nucleus of a variety of mammals, but the specificity with respect to particular cell types has proven elusive at the light microscopic level. We sought to identify cell types in the superficial regions of the dorsal cochlear nucleus that were immunoreactive to glycine using light and electron microscopy in the rat. At the light microscopic level, glycine immunoreactivity was present in some but not all medium-sized cells in layers I and II. The somata of pyramidal and granule cells were not stained. At the electron microscopic level, using previously published ultrastructural criteria, we examined the glycine-labeled cells and determined that many but not all cartwheel cells were labeled. We also observed unlabeled unipolar brush cells, Golgi cells, and stellate cells. As some of the labeled cells could not be identified, we could not determine whether unipolar brush cells, Golgi cells or stellate cells had both labeled and unlabeled subpopulations. Our observations indicate that within the population of cartwheel cells, only a subset are glycine-immunoreactive.
Gates
T S
TS
Department of Otolaryngology-HNS, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Weedman
D L
DL
Pongstaporn
T
T
Ryugo
D K
DK
D000818:Animals; D017626:Cochlear Nucleus / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure*; D005998:Glycine / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013194:Staining and Labeling; D009435:Synaptic Transmission / Q000502:physiology
D016194:Receptors, N-Methyl-D-Aspartate; D005998:Glycine