Insulin receptors co-localize with TRPV1, CGRP, and Substance P on sensory neurons, with visceral neurons expressing more insulin receptors than somatic ones.
InsR + CGRP + SPinsulin receptors are physically co-located with pain neuropeptides on sensory neurons, directly linking insulin signaling to pain modulation
What the researchers found
Insulin receptors are expressed on a specific subset of sensory neurons in both the central and peripheral nervous system. Quantitative studies revealed that visceral (organ-supplying) sensory neurons express more insulin receptors than somatic (skin/muscle) sensory neurons.
InsR co-localizes with TRPV1 (a pain channel), CGRP, and substance P in these neurons. This co-expression means insulin signaling can directly modulate pain transmission and neurogenic inflammation.
The functional significance includes modulation of ion channels involved in pain, regulation of neuropeptide release (CGRP and substance P), and neurotrophic effects on nerve growth, development, and regeneration. Recent studies reveal important roles for insulin in axonal growth and repair.
Why it matters
Diabetic patients commonly experience altered pain sensitivity and nerve damage (neuropathy). Understanding how insulin directly affects pain-sensing neurons through neuropeptide pathways could explain these symptoms and lead to targeted treatments.
The finding that visceral sensory neurons are particularly enriched in insulin receptors explains why organs like the pancreas and bladder are especially vulnerable to inflammation in metabolic disease.
The numbers in context
InsR co-localizes with TRPV1, CGRP, substance P; visceral > somatic InsR expression; modulates pain, inflammation, nerve growth
How the study worked
This is a review article summarizing immunohistochemical, electrophysiological, and molecular studies on insulin receptor expression and function in primary sensory neurons, with focus on co-localization with pain-related channels and neuropeptides.
Who was studied
N/A (literature review of sensory neuron studies)
What this study cannot tell us
This is a review article synthesizing existing data. Many of the findings are from animal studies, and the extent to which they translate to human patients is not fully established.
The functional consequences of InsR-neuropeptide interactions in specific disease states remain to be directly tested.
How to read the evidence
Review-level evidence synthesizing immunohistochemical, electrophysiological, and molecular studies. Most data from animal studies.
When this study was published
Published in 2020. Insulin's direct neuronal effects are being further investigated for diabetic neuropathy treatment.
The bigger picture
Diabetic neuropathy and altered pain sensitivity are among the most common complications of diabetes. This review provides the molecular explanation: insulin directly modulates the same neurons and neuropeptides that control pain. Loss of insulin signaling in these neurons could drive diabetic neuropathy.
Questions still open
- Could insulin treatment directly reduce diabetic neuropathy pain?
- Does insulin resistance in neurons precede clinical neuropathy?
- Why do visceral neurons have more insulin receptors?
Common questions
How does diabetes cause nerve pain?
Could insulin help treat nerve pain?
Read the original research
Modulation of Sensory Nerve Function by Insulin: Possible Relevance to Pain, Inflammation and Axon Growth.
International journal of molecular sciences, 21(7)
Citation
Lázár, Bence András; Jancsó, Gábor; Sántha, Péter. (2020). Modulation of Sensory Nerve Function by Insulin: Possible Relevance to Pain, Inflammation and Axon Growth.. International journal of molecular sciences, 21(7). https://doi.org/10.3390/ijms21072507