Sensitization of insensitive branches of C nociceptors in human skin
- PMID: 7869253
- PMCID: PMC1155854
- DOI: 10.1113/jphysiol.1994.sp020368
Sensitization of insensitive branches of C nociceptors in human skin
Abstract
1. Eighteen cutaneous mechanosensitive C nociceptors were recorded from the peroneal nerves of healthy human subjects. Their identity was continuously monitored by intracutaneous electrical stimulation, and their activation by mechanical or transcutaneous electrical stimulation was detected by slowing of conduction velocity during the relative refractory period. 2. Mechanoreceptive fields (mRFs) mapped with suprathreshold von Frey hair stimuli covered an area of 99 +/- 21 mm2 (mean +/- S.E.M.). Two of the units had separate mRFs, with borders about 0.5-1.5 cm apart from each other and the largest of these units had a maximal diameter of 4.5 cm. 3. Successive topical application of mustard oil and capsaicin induced expansions of mRFs by 57 +/- 14 mm2 in eight of fifteen units. 4. In twelve units transcutaneous electrical stimulation delivered through a pointed electrode was used for mapping the electroreceptive fields (eRFs). The borders of the eRFs and the mRFs were identical for two of twelve units only. In the other ten units additional mechano-insensitive areas (55 +/- 22 mm2) were detected from which transcutaneous electrical stimuli could activate the respective unit. 5. Application of mustard oil and capsaicin to these mechano-insensitive areas sensitized five of eight units to mechanical stimuli. In these cases the mRF after sensitization exactly corresponded to the eRF. 6. It is concluded that there are insensitive branches in human mechanosensitive cutaneous C nociceptors that can be detected by transcutaneous electrical stimulation and sensitized by topical application of chemical irritants. Activation of those branches in the course of inflammatory processes may contribute to spatial summation at central synapses and hence to hyperalgesia.
Similar articles
-
Innervation territories of mechanically activated C nociceptor units in human skin.J Neurophysiol. 1997 Nov;78(5):2641-8. doi: 10.1152/jn.1997.78.5.2641. J Neurophysiol. 1997. PMID: 9356413
-
Novel classes of responsive and unresponsive C nociceptors in human skin.J Neurosci. 1995 Jan;15(1 Pt 1):333-41. doi: 10.1523/JNEUROSCI.15-01-00333.1995. J Neurosci. 1995. PMID: 7823139 Free PMC article.
-
Innervation territories of mechano-insensitive C nociceptors in human skin.J Neurophysiol. 2002 Oct;88(4):1859-66. doi: 10.1152/jn.2002.88.4.1859. J Neurophysiol. 2002. PMID: 12364512
-
Peripheral and central mechanisms of cutaneous hyperalgesia.Prog Neurobiol. 1992;38(4):397-421. doi: 10.1016/0301-0082(92)90027-c. Prog Neurobiol. 1992. PMID: 1574584 Review.
-
Advancing the Understanding of Acupoint Sensitization and Plasticity Through Cutaneous C-Nociceptors.Front Neurosci. 2022 May 10;16:822436. doi: 10.3389/fnins.2022.822436. eCollection 2022. Front Neurosci. 2022. PMID: 35620665 Free PMC article. Review.
Cited by
-
Radiation of pain: Psychophysical evidence for a population coding mechanism in humans.bioRxiv [Preprint]. 2024 Aug 29:2024.04.02.587666. doi: 10.1101/2024.04.02.587666. bioRxiv. 2024. Update in: Pain. 2025 Jun 1;166(6):1285-1295. doi: 10.1097/j.pain.0000000000003474. PMID: 38617343 Free PMC article. Updated. Preprint.
-
Trpv1 mediates spontaneous firing and heat sensitization of cutaneous primary afferents after plantar incision.Pain. 2009 Jan;141(1-2):41-51. doi: 10.1016/j.pain.2008.10.004. Epub 2008 Nov 17. Pain. 2009. PMID: 19010598 Free PMC article.
-
Microneurographic assessment of C-fibre function in aged healthy subjects.J Physiol. 2009 Jan 15;587(2):419-28. doi: 10.1113/jphysiol.2008.162941. Epub 2008 Dec 8. J Physiol. 2009. PMID: 19064617 Free PMC article.
-
Specific C-receptors for itch in human skin.J Neurosci. 1997 Oct 15;17(20):8003-8. doi: 10.1523/JNEUROSCI.17-20-08003.1997. J Neurosci. 1997. PMID: 9315918 Free PMC article.
-
Quantitative Thermal Testing Profiles as a Predictor of Treatment Response to Topical Capsaicin in Patients with Localized Neuropathic Pain.Pain Res Treat. 2017;2017:7425907. doi: 10.1155/2017/7425907. Epub 2017 Feb 21. Pain Res Treat. 2017. PMID: 28321335 Free PMC article.
References
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Miscellaneous