Journal of Neuroscience, Vol 7, 2674-2687, Copyright © 1987 by Society for Neuroscience
Dual intrinsic and extrinsic origins of CGRP- and NPY-immunoreactive nerves of rat gut and pancreas
HC Su, AE Bishop, RF Power, Y Hamada and JM Polak
The origins of nerves containing calcitonin gene-related peptide (CGRP),
neuropeptide Y (NPY), and substance P were investigated in the rat stomach,
pancreas, and colon, using immunocytochemistry combined with retrograde
tracing and surgical and chemical denervation procedures. Compared with
nerves containing vasoactive intestinal polypeptide (VIP) and galanin,
which have primarily local origins in mammalian gut, CGRP-, NPY-, and
substance P-immunoreactive nerves revealed dual extrinsic and intrinsic
origins. Immunocytochemistry combined with retrograde tracing showed that
the extrinsic CGRP- and substance P-immunoreactive nerves in the stomach
and pancreas originate from bilateral dorsal root ganglia mainly at levels
T8-T11, while those of the colon are derived from bilateral ganglia at S1
and, to a lesser extent, L1 and L6. Chemical denervations showed that
neurons in these ganglia form a sensory input to the gut, and that those
containing CGRP form the largest proportion. The results of combined
retrograde tracing and immunocytochemistry indicated that extrinsic
NPY-immunoreactive nerves originate from postganglionic sympathetic neurons
lying in the coeliac and inferior mesenteric ganglia. These nerves were
located mainly around blood vessels in gut and pancreas, showed sensitivity
to 6-hydroxydopamine, and thus are likely to be noradrenergic. The present
study provides a detailed mapping of the origins of some of the major
peptide-containing nerves of the rat gastroenteropancreatic tract, thus
providing further information on the anatomy of the enteric innervation.
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