Effect of axotomy on expression of NPY, galanin, and NPY Y1 and Y2 receptors in dorsal root ganglia and the superior cervical ganglion studied with double-labeling in situ hybridization and immunohistochemistry
Experimental Neurology. 2000-04-01; 162(2): 361-384
DOI: 10.1006/exnr.1999.7329
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1. Exp Neurol. 2000 Apr;162(2):361-84.
Effect of axotomy on expression of NPY, galanin, and NPY Y1 and Y2 receptors in
dorsal root ganglia and the superior cervical ganglion studied with
double-labeling in situ hybridization and immunohistochemistry.
Landry M(1), Holmberg K, Zhang X, Hökfelt T.
Author information:
(1)Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Using double-labeling techniques for both in situ hybridization and
immunohistochemistry some peptides and peptide receptors were studied
quantitatively in a sensory and a sympathetic ganglion after axotomy. In the
lumbar 5 dorsal root ganglion (DRG) normally no neuropeptide Y- and only a few
galanin-positive cell bodies are seen. Following complete transection of the
sciatic nerve around 60% of all neuropeptide Y (NPY) neuron profiles (NPs) were
galanin positive (+) and 33-44% of all galanin NPs were NPY(+). A good agreement
between immunohistochemistry and in situ hybridization was observed for NPY and
galanin. NPY Y1- and Y2-receptor (R) mRNAs were found in around 40% of all NPY
mRNA(+) NPs, and more than half of the Y1-R mRNA(+) NPs and two-thirds of the
Y2-R mRNA(+) NPs were NPY(+). In addition, more than one-third of the galanin
mRNA-containing NPs showed colocalization with NPY receptor mRNAs and up to 70%
of the Y2-R mRNA(+) NPs also expressed galanin mRNA. In the control superior
cervical ganglion (SCG) 10% of the NPY(+) NPs were Y2-R mRNA(+), and 85% of the
Y2-R(+) NPs were NPY mRNA(+), and the corresponding percentages after axotomy
were around 35 and 45%, respectively. Following axotomy of the carotid nerves
around half of all NPY(+) NPs were galanin(+), and conversely around 50% of all
galanin NPs were NPY(+) at the mRNA level, whereas much lower percentages (15 and
9%, respectively) were observed with immunohistochemistry. These results
demonstrate that double-labeling procedures are valid tools to quantitatively
evaluate coexistence situations in sensory and sympathetic ganglia, showing a
high degree of coexistence for NPY and galanin in axotomized neurons both in the
lumbar 5 DRG and in the SCG. However, the immunohistochemical analysis in the SCG
demonstrated much lower numbers of peptide-positive neurons than seen with in
situ hybridization, suggesting that the latter technique is more sensitive. The
fact that a considerable number of neurons express NPY together with Y1- and/or
Y2-Rs indicates that both receptors may act as autoreceptors, the Y1-R presumably
at the level of the cell body and the Y2-R on nerve terminals in the dorsal horn
and/or the periphery. The present results also show that in both sensory and
sympathetic neurons there is a strong upregulation of the Y2-R after nerve
injury, suggesting a possible role in trophic and regenerative events.
Copyright 2000 Academic Press.
DOI: 10.1006/exnr.1999.7329
PMID: 10739642 [Indexed for MEDLINE]