Journal of Neuroscience, Vol 6, 127-133, Copyright © 1986 by Society for Neuroscience
Immunoreactive dynorphin B in sacral primary afferent fibers of the cat
AI Basbaum, L Cruz and E Weber
Immunocytochemical analysis of the distribution of dynorphin B terminals in
the sacral spinal cord of the cat revealed a pattern of staining very
similar to that produced with antisera directed against the primary
afferent derived, putative neurotransmitter, vasoactive intestinal
polypeptide. Labeled axons and terminals were concentrated in lamina I and
V and there was dense fiber staining in the tract of Lissauer. Of
particular interest was the presence of immunoreactive axons in attached
dorsal rootlets. To specifically focus on the possibility that some of the
sacral primary afferent fibers are dynorphin-immunoreactive, we first tried
to increase perikaryal labeling in the sacral dorsal root ganglia by
topical treatment with colchicine. This did not produce immunoreactive
labeling of cell bodies in the ganglia. Unilateral multiple dorsal
rhizotomy (L5 to coccygeal 1), however, significantly decreased the
staining of dynorphin- immunoreactive axons and terminals in the tract of
Lissauer and in the dorsal horn of sacral segments ipsilateral to the
deafferentation. No changes were detected in the lumbar cord. Finally,
radioimmunoassay of caudal lumbar and sacral dorsal root ganglia was
performed. Measurable immunoreactivity was found in all ganglia assayed,
but, consistent with the histochemical analysis, sacral ganglia contained
the highest concentration of immunoreactive dynorphin B. These data
indicate that a significant component of the sacral spinal cord dynorphin
terminal immunoreactivity derives from primary afferent fibers.(ABSTRACT
TRUNCATED AT 250 WORDS)