Differential distribution of nerve terminals immunoreactive for substance P and cholecystokinin in the sympathetic preganglionic cell column of the filefish Stephanolepis cirrhifer
K. Funakoshi et al., Differential distribution of nerve terminals immunoreactive for substance P and cholecystokinin in the sympathetic preganglionic cell column of the filefish Stephanolepis cirrhifer, J COMP NEUR, 428(1), 2000, pp. 174-189
Immunoreactivity for substance P and cholecystokinin-8 was examined in the
nerve fibers in the central autonomic nucleus, a cell column for sympatheti
c preganglionic neurons, in the filefish Stephanolepis cirrhifer. Substance
P-immunoreactive fibers were distributed throughout the entire rostrocauda
l extent, but were more abundant in the caudal part of the column, where su
bstance P-immunoreactive varicosities sometimes made contacts with the symp
athetic preganglionic neurons. Cholecystokinin-8-immunoreactive fibers were
found almost entirely in the rostral part of the column, where a dense net
work of varicosities was in close apposition to a considerable number of th
e sympathetic preganglionic neurons. Double labeling immunohistochemistry s
howed that substance P fibers and cholecystokin-8 fibers were entirely diff
erent, and distinct from serotonin-immunoreactive fibers. By using immunoel
ectron microscopy, synaptic specialization was sometimes observed between t
he dendrites of preganglionic neurons and varicosities immunoreactive for s
ubstance P and cholecystokinin-8. Substance P- and cholecystokinin-8 fibers
were seen from the descending trigeminal tract, through the dorsolateral f
uniculus and the ventral portion of the dorsal horn, to the central autonom
ic nucleus. After colchicine treatment, substance P-immunoreactive perikary
a were found in the cranial and spinal sensory ganglia. These results sugge
st that the sympathetic preganglionic neurons of the filefish receive inner
vation by substance P fibers and cholecystokinin fibers, and that the forme
r might be of primary sensory origin. Topographical distribution of cholecy
stokinin-8-immunoreactive terminals in the central autonomic nucleus along
the rostrocaudal extent might underlie the differential regulation of sympa
thetic activity via a distinct population of sympathetic preganglionic neur
ons. (C) 2000 Wiley-Liss, Inc.