Journal of Neuroscience, Vol 8, 3035-3056, Copyright © 1988 by Society for Neuroscience
An atlas of a rare neuronal surface antigen in the rat central nervous system
DT Stephenson and PD Kushner
ALS and Neuromuscular Research Foundation, Pacific Presbyterian Medical Center, San Francisco, California 94115.
The mature nervous system contains functional synaptic networks composed of
neuronal sets and subsets whose identity and maintenance may rely on
external surface molecules specific for these neuronal subdivisions. Such
molecules may reside permanently on specific neurons, serving to identify
those neurons within a complex population. From a collection of monoclonal
antibodies made to the Torpedo cholinergic synaptosome preparation, we have
identified several antibodies that bind the surface of some, but not all,
neurons of the mature rat brain (Kushner and Stephenson, 1983; Kushner,
1984). In the present study we catalog which neurons of the entire rat
brain and spinal cord are immunopositive for one of these antibodies, Tor
23. The atlas we have compiled can be used (1) on a practical level to
guide affinity purifications and neuronal cell sorting, and (2) more
esoterically to address whether surface antigenic sets of neurons share or
define a common functional property. In the forebrain, Tor 23- positive
neurons predominate as a rare cell type of the inner cortical laminae. In
the midbrain, few cells stain. In the hindbrain, labeled neurons are
dispersed among several nuclei. The exceptions to these observations, areas
that almost exclusively contain Tor 23- immunopositive neurons, are the
spinal cord ventral horn, the deep cerebellar nuclei, some
cerebellar-related nuclei, selected auditory nuclei, the supraoptic and
paraventricular nuclei of the hypothalamus, and the CA2 pyramidal neurons
of the hippocampus. The neurons that bind Tor 23 are related biochemically
by virtue of that shared epitope alone. Whether they are related in a
functional manner is a separate issue. Tor 23 demarks many motor-related
structures, specifically, the ventral horn motor lamina, the orofacial
motor nuclei 5 and 7, the ambiguus nucleus, the deep cerebellar nuclei, the
pontine reticulotegmental nucleus, the lateral reticular nucleus, the
gigantocellular reticular nucleus, the red nucleus, and neurons within the
motor and somatosensory cortices. The overlap of Tor 23 with motor
structures suggests that Tor 23 is a motor system marker.