POSTER PRESENTATION
Title : Differential
Expression of the Insulin Receptor in Primary Sensory Neurons Innervating
Somatic and Visceral Organs
Author : Bence
Andras Lazar
University of Szeged, Hungary
Abstract : In recent years, several studies
indicated functional interactions between the insulin receptor (InsR) and the
transient receptor potential vanilloid type 1 receptor (TRPV1) co-expressed in
a subset of primary sensory #neurons (PSNs) of unidentified target innervation.
The aim of the present study was to reveal the target-specific expression of
the InsR and its co-localization with TRPV1 in adult rats. Adult male Wistar
rats (n=12) weighing 300-350 g were used. To identify somatic and visceral PSNs
biotin-conjugated wheat germ agglutinin (bWGA) was injected into the hind paw
skin, the lateral gastrocnemius muscle, the pancreas and the urinary bladder.
Three days later representative serial sections were cut from Th10-13 and
L3-S1 dorsal root ganglia. Immunohistochemistry and
quantitative morphometry were used to analyze the expression of InsR and TRPV1
in bWGA-labelled somatic and visceral PSNs. The largest proportions of
retrogradely labelled InsR-positive neurons were identified among PSNs serving
the pancreas (~54%) and the urinary bladder (~52%). InsR-positive neurons
innervating the hind paw skin and the gastrocnemius muscle amounted to ~22% and
~21% of labelled neurons. The majority (~64%) of the labelled PSNs exhibited
TRPV1 immunoreactivity. Co-localization of the TRPV1 and the InsR was observed
in ~16%, ~15%, ~29% and ~30% of labelled cutaneous, muscular, pancreatic and
urinary bladder PSNs. Our quantitative morphological data provide evidence for
the co-localization of InsR and TRPV1 in PSNs innervating somatic and visceral
organs and demonstrate a preponderance of InsR-immunoreactivity among PSNs
which innervate visceral targets. These findings suggest that visceral spinal
PSNs might be more sensitive to the modulatory influence of insulin than PSNs
innervating somatic organs.
Keywords: insulin receptor; transient receptor
potential vanilloid type 1 receptor; primary
sensory neurons; retrograde
labelling; somatic and visceral organs.
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