Insulin confers differing effects on neurite outgrowth in separate populations of cultured dorsal root ganglion neurons: the role of the insulin receptor
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Published version
Author(s)
Type
Journal Article
Abstract
Apart from its pivotal role in the regulation of carbohydrate metabolism, insulin exerts important neurotrophic and neuromodulator effects on dorsal root ganglion (DRG) neurons. The neurite outgrowth-promoting effect is one of the salient features of insulin’s action on cultured DRG neurons. Although it has been established that a significant population of DRG neurons express the insulin receptor (InsR), the significance of InsR expression and the chemical phenotype of DRG neurons in relation to the neurite outgrowth-promoting effect of insulin has not been studied. Therefore, in this study by using immunohistochemical and quantitative stereological methods we evaluated the effect of insulin on neurite outgrowth of DRG neurons of different chemical phenotypes which express or lack the InsR. Insulin, at a concentration of 10 nM, significantly increased total neurite length, the length of the longest neurite and the number of branch points of cultured DRG neurons as compared to neurons cultured in control medium or in the presence of 1 μM insulin. In both the control and the insulin exposed cultures, ∼43% of neurons displayed InsR-immunoreactivity. The proportions of transient receptor potential vanilloid type 1 receptor (TRPV1)-immunoreactive (IR), calcitonin gene-related peptide (CGRP)-IR and Bandeiraea simplicifolia isolectin B4 (IB4)-binding neurons amounted to ∼61%, ∼57%, and ∼31% of DRG neurons IR for the InsR. Of the IB4-positive population only neurons expressing the InsR were responsive to insulin. In contrast, TRPV1-IR nociceptive and CGRP-IR peptidergic neurons showed increased tendency for neurite outgrowth which was further enhanced by insulin. However, the responsiveness of DRG neurons expressing the InsR was superior to populations of DRG neurons which lack this receptor. The findings also revealed that besides the expression of the InsR, inherent properties of peptidergic, but not non-peptidergic nociceptive neurons may also significantly contribute to the mechanisms of neurite outgrowth of DRG neurons. These observations suggest distinct regenerative propensity for differing populations of DRG neurons which is significantly affected through insulin receptor signaling.
Date Issued
2018-10-10
Date Acceptance
2018-09-24
Citation
Frontiers in Neuroscience, 2018, 12
ISSN
1662-4548
Publisher
Frontiers Media
Journal / Book Title
Frontiers in Neuroscience
Volume
12
Copyright Statement
© 2018 Lázár, Jancsó, Pálvölgyi, Dobos, Nagy and Sántha. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Subjects
Science & Technology
Life Sciences & Biomedicine
Neurosciences
Neurosciences & Neurology
insulin
neurite outgrowth
dorsal root ganglion neurons
insulin receptor
transient receptor potential vanilloid type 1 receptor
calcitonin gene-related peptide
isolectin B4
PRIMARY SENSORY NEURONS
NERVE GROWTH-FACTOR
ADULT-RAT
CAPSAICIN RECEPTOR
LOCAL INSULIN
DRG NEURONS
ION-CHANNEL
FACTOR-I
INFLAMMATION
EXPRESSION
1109 Neurosciences
1702 Cognitive Science
Publication Status
Published
Article Number
ARTN 732