AN IMMUNOCYTOCHEMICAL INVESTIGATION OF THE RELATIONSHIP BETWEEN SUBSTANCE-P AND THE NEUROKININ-1 RECEPTOR IN THE LATERAL HORN OF THE RAT THORACIC SPINAL-CORD
R. Pollock et al., AN IMMUNOCYTOCHEMICAL INVESTIGATION OF THE RELATIONSHIP BETWEEN SUBSTANCE-P AND THE NEUROKININ-1 RECEPTOR IN THE LATERAL HORN OF THE RAT THORACIC SPINAL-CORD, Brain research, 777(1-2), 1997, pp. 22-30
The relationship between substance P-containing axons and sympathetic
preganglionic neurons possessing the neurokinin-l receptor was investi
gated in the lateral horn of the rat thoracic spinal cord, Sympathetic
preganglionic neurons were labelled retrogradely with Fluorogold. Sec
tions containing labelled cells were reacted with antibodies against c
holine acetyltransferase. substance P and the neurokinin-l receptor an
d examined with three-colour confocal laser scanning microscopy. In al
l, 95 sympathetic preganglionic neurons were examined and 79% of these
were immunoreactive for the neurokinin-l receptor. Substance P-immuno
reactive axons not only made contacts with preganglionic neurons which
were immunoreactive for the receptor but also made contacts with cell
s which did not express the receptor. Dendrites, labelled with immunor
eactivity for choline actyltransferase. also received contacts from su
bstance P-immunoreactive varicosities but this was not related to the
presence or the absence of receptor, An electron microscopic analysis
was performed to investigate the relationship between substance P-cont
aining boutons and dendrites possessing the neurokinin-1 receptor. Imm
unoreactivity for substance P was detected with peroxidase immunocytoc
hemistry and immunoreactivity for the receptor was detected with the s
ilver-intensified gold method. Substance P-containing boutons made syn
apses with dendrites which were positively and negatively labelled for
the receptor. Receptor immunoreactivity was not usually present at sy
napses formed by substance P boutons with neurokinin-l-immunoreactive
dendrites. It is concluded that substance P may modulate much of the a
ctivity of sympathetic preganglionic neurons through an indirect non-s
ynaptic mechanism. (C) 1997 Elsevier Science B.V.