Journal of Neuroscience, Vol 7, 1250-1263, Copyright © 1987 by Society for Neuroscience
Molecular markers of neuronal subpopulations in layers 4, 5, and 6 of cat primary visual cortex
Y Arimatsu, JR Naegele and CJ Barnstable
Cat primary visual cortex has been used as an immunogen to produce
monoclonal antibodies that detect subpopulations of neurons. When tested by
immunofluorescence on tissue sections of areas 17 and 18, 2 of these
antibodies, VC1.1 and VC5.1, outlined a rare subpopulation of neurons
located mainly in layer 4 but also in layers 5 and 6. Double- labeling
immunofluorescence experiments in area 17 revealed that all VC1.1-reactive
cells were also VC5.1-reactive and 83% of VC5.1-reactive cells were
VC1.1-reactive, suggesting that the antibodies were reacting with the same
subpopulation of cells. Both antibodies labeled similar or identical
subpopulations of cells in other areas of the cat CNS, including the
superior colliculus, parts of hippocampus, cerebellar deep nuclei, and
rostral spinal cord. Neither antibody labeled cell bodies in the lateral
geniculate nucleus. In the retina, VC1.1 labeled cell bodies and processes
of some horizontal and amacrine cells, whereas VC5.1 labeled only ganglion
cell axons. In the cerebellar cortex, the most prominent labeling of VC1.1
was of Purkinje cells, whereas that of VC5.1 was of Lugaro cells.
Immunoblotting analyses of cat cortical homogenates demonstrated that VC1.1
recognized a major polypeptide band of Mr 95,000-105,000 and additional
bands of Mr 145,000 and Mr 170,000. VC5.1 recognized bands of Mr 97,000 and
Mr 150,000. Subcellular fractionation and extraction studies showed that
the VC1.1 antigens were integral membrane proteins preferentially located
in a synaptosomal plasma membrane fraction. The VC5.1 antigens were
preferentially located in a soluble cytoplasmic or extracellular fraction.
The results indicate that antibodies VC1.1 and VC5.1 recognize unique
epitopes in the cat CNS and define a previously unrecognized subpopulation
of cells in cat visual cortex.
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