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Interaction between enkephalin and γ‐aminobutyric acid in the chicken retina: A double‐label immunoelectron microscopic analysis
Author(s) -
Watt Carl B.,
Glazebrook Patricia A.
Publication year - 1994
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/cne.903420306
Subject(s) - amacrine cell , gabaergic , postsynaptic potential , enkephalin , biology , immunoelectron microscopy , neuroscience , population , inhibitory postsynaptic potential , retina , microbiology and biotechnology , biochemistry , immunohistochemistry , immunology , receptor , demography , sociology , opioid
In the present study, double‐label immunoelectron microscopy was used to examine the synaptic relationships between amacrine cell populations in the chicken retina that contain either enkephalin or γ‐aminobutyric acid (GABA) or both enkephalin and GABA. The objectives of the present study were twofold. First, the ultrastructural features and synaptic organization of enkephalin and enkephalin/GABA amacrine cells were compared. Second, the synaptic interactions between these populations and the population of GABA amacrine cells were examined. A total of 475 synaptic arrangements were observed to involve enkephalin or enkephalin/GABA amacrine cell processes. The synaptic relationships of enkephalin and enkephalin/GABA amacrine cells were quite similar. Each population was pre‐ and postsynaptic to amacrine cells, postsynaptic to bipolar cells, and presynaptic to processes possibly originating from ganglion cells. A substantial percentage of each population's pre‐ and postsynaptic relationships were with the processes of GABAergic amacrine cells. Moreover, when enkephalin and enkephalin/ GABA amacrine cell processes were postsynaptic to bipolar cells, their dyadic partner was observed frequently to be a GABA amacrine cell process. The present study suggests a diversity in the population of chicken enkephalin amacrine cells with respect to their expression of the classical inhibitory transmitter GABA. Moreover, a functional relationship between enkephalinergic and GABAergic pathways is indicated by studies showing that both enkephalin and enkephalin/GABA amacrine cells exhibit substantial synaptic interaction with GABA amacrine cells. © 1994 Wiley‐Liss, Inc.