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Localization and Quantitative Autoradiography of Glutamatergic Ligand Binding Sites in Chick Brain
Author(s) -
Henley Jeremy M.,
Moratallo Rosario,
Hunt Stephen P.,
Barnard Eric A.
Publication year - 1989
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1989.tb00358.x
Subject(s) - glutamatergic , neuroscience , ligand (biochemistry) , chemistry , biology , glutamate receptor , receptor , biochemistry
The anatomical localization of glutamate receptor subtype‐selective ligand binding sites was investigated in 1‐day‐old chick brain using quantitative autoradiography. Under the conditions used, the regional distributions of [ 3 H]glutamate, [ 3 H]AMPA (a selective quisqualate receptor ligand) and [ 3 H]kainate binding sites are manifestly different. [ 3 H]L‐glutamate binding is densely localized in the telencephalon, particularly in the neostriatum (2.8 pmol/mg protein). In addition, [ 3 H]L‐glutamate labels the thalamus, the nucleus mesencephalicus lateralis pars dorsalis, the superficial layers of the optic tectum and the molecular layer of the cerebellum. [ 3 H]AMPA binding sites are most densely localized in the hippocampus (0.90 pmol/mg protein), with an otherwise relatively uniform distribution of binding within the telencephalon. [ 3 H]AMPA also labels the striatum griseum et fibrosum superficiale of the optic tectum and the molecular layer of the cerebellum. [ 3 H]Kainate binding sites are extremely densely packed in the molecular layer of the cerebellum (10 pmol/mg protein). Other regions of [ 3 H]kainate binding include the hyperstriatum and the thalamus. The binding of the NMDA receptor channel blocker [ 3 H]MK‐801 is increased in the presence of 1 mM L‐glutamate. [ 3 H]MK‐801 binding is generally widespread in the telencephalon but is notably absent from the ectostriatum. No evidence of [ 3 H]MK‐801 binding sites was detected in the cerebellum, even in the presence of 1 mM L‐glutamate. The relatively high densities and the well‐defined localizations of the glutamate receptor subtype binding sites suggest that chick brain provides a useful system for the further study of excitatory amino acid receptors.