Journal of Neuroscience, Vol 10, 2438-2450, Copyright © 1990 by Society for Neuroscience
Distribution and plasticity of immunocytochemically localized GABAA receptors in adult monkey visual cortex
SH Hendry, J Fuchs, AL deBlas and EG Jones
Department of Anatomy and Neurobiology, University of California, Irvine 92717.
Immunocytochemical methods were used to reveal new details of the
distribution and plasticity of GABAA receptors in the visual cortex of
adult monkeys; the findings were compared with those of autoradiographic
experiments involving the binding of 3H-muscimol and 3H-flunitrazepam. In
both areas 17 and 18, a monoclonal antibody to the purified GABAA complex
(deBlas et al., 1988) produced staining of punctate profiles in the
neuropil and around cell bodies and large processes in layers I-VI. The
receptor immunostaining was relatively intense in layers II-III, IVA, IVC
beta, and VI; these alternated with lightly stained layers I, IVB, IVC
alpha, and V. In area 18, the laminar pattern was similar except that layer
IV was split into a superficial, lightly stained half and a deep, intensely
stained half. In sections cut parallel to the pial surface, receptor
distribution in most layers was found to be uniform. There were 3
exceptions in area 17: (1) patches of intense receptor staining were
present in layers II and III; (2) a widely spaced, irregular lattice of
intense staining was found in layer IVA; and (3) a much finer, regular
lattice was present in layer IVC. The patches in layers II-III and the
lattice in layer IVA coincided precisely with regions of intense cytochrome
oxidase (CO) staining. The binding of 3H-muscimol and 3H-flunitrazepam
revealed a laminar pattern that was similar in most respects, including
greater ligand binding in layer IVA of area 17, but showed no evidence of
the sublaminar organization in layers IVA and IVC beta. Inhomogeneities in
receptor immunostaining but not ligand binding were also seen in layer III
of area 18. Following a 5 or 10 d period in which intravitreal injections
of TTX had silenced ganglion cell activity in one retina, GABAA receptor
immunostaining in layer IVC beta was distributed in intensely stained
stripes, 450-550 microns wide, that alternated with narrower, lightly
stained stripes. Stripes were also seen with receptor immunostaining and
with the binding of the 2 radioligands in layer IVC beta of monocularly
enucleated monkeys. Comparison with CO staining revealed that the stripes
of reduced immunostaining or ligand binding corresponded to columns
dominated by the TTX-injected or enucleated eye. Quantitatively, the
binding in the deprived eye columns was reduced by 25%.(ABSTRACT TRUNCATED
AT 400 WORDS)
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