Journal of Neuroscience, Vol 5, 2051-2059, Copyright © 1985 by Society for Neuroscience
An immunohistochemical and quantitative examination of dorsal root ganglion neuronal subpopulations
J Price
Sensory neurons of adult rat lumbar dorsal root ganglia were labeled in
cryostat sections with antisera against tyrosine hydroxylase (TH),
substance P (SP), and somatostatin (SOM), and with a monoclonal antibody
(RT97) that labels the 145- and 200-kilodalton (kd) subunits of
neurofilaments. These neurons were also histochemically stained for
fluoride-resistant acid phosphatase (FRAP), and the size and distribution
of each population were determined. In addition, the double-label
immunoperoxidase technique of Sternberger and Joseph (Sternberger, L.A.,
and S.A. Joseph (1979) J. Histochem. Cytochem. 27: 1424-1429) was employed
to determine whether these antibodies labeled distinct or overlapping
populations of neurons. The results indicate that the dopaminergic (TH+)
cells constitute a separate population from the SP+ and SOM+ neurons and
that the size distributions of the SP+, SOM+, TH+, and FRAP+ cells are all
different despite the fact that all of these subpopulations are part of the
"small dark" subpopulation as indicated by their size and by the fact that
they are RT97-. RT97 is a putative marker for the "large light" population
(Anderton, B., H.B. Coakham, J. A. Garson, A.A. Harper, and S.N. Lawson
(1982) J. Physiol. (Lond.) 334: 97-98P). Furthermore, the distribution data
indicate that all of the "small dark" cell subpopulations are not evenly
distributed within the ganglion, and the staining with RT97 and with
another antibody which recognizes the 68-kd neurofilament subunit indicates
heterogeneity among the "large light" population. These results are
discussed in terms of the significance of the "small dark"-"large light"
classification.
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