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Evidence for the inhibitory neurotransmitter γ‐aminobutyric acid in aspiny and sparsely spiny nonpyramidal neurons of the turtle dorsal cortex
Author(s) -
Blanton Mark G.,
Shen Janet M.,
Kriegstein Arnold R.
Publication year - 1987
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.902590208
Subject(s) - gabaergic , biology , neuroscience , inhibitory postsynaptic potential , glutamate decarboxylase , gamma aminobutyric acid , medium spiny neuron , golgi apparatus , neuropil , microbiology and biotechnology , dopamine , central nervous system , biochemistry , enzyme , striatum , receptor , endoplasmic reticulum
In order to learn more about the anatomical substrate for γ‐aminobutyric acid (GABA)‐mediated inhibition in cortical structures, the intrinsic neuronal organization of turtle dorsal cortex was studied by using Golgi impregnation, immunohistochemical localization of GABA and its synthetic enzyme glutamic acid decarboxylase (GAD), and histochemical localization of the presynaptic GABA‐degrading enzyme GABA‐transaminase (GABA‐T). GABAergic markers are found in neurons identical in morphology and distribution to Golgi‐impregnated aspiny and sparsely spiny nonpyramidal neurons with locally arborizing axons and appear to label most if not all of the nonpyramidal neurons. In addition, the GABAergic markers are found in punctate structures in a distribution characteristic of presumed inhibitory terminals. The spine‐laden pyramidal neurons, the principal projecting cell type in the dorsal cortex, are devoid of labelling for GABAergic markers but are surrounded by presumed GABAergic terminals. The data complement previous physiological and ultrastructural studies that implicate aspiny and sparsely spiny nonpyramidal neurons as mediators of intrinsic inhibition of pyramidal neurons in turtle cortex. The results also suggest similarities in the functional organization of intrinsic inhibitory elements in turtle and mammalian cortex.