Pain signals can travel as fast as touch signals, according to a new study. The discovery of a rapid pain-signalling system challenges our current understanding of pain. The study is published in the scientific journal Science Advances.
It has until now been believed that nerve signals for pain are always conducted more slowly than those for touch. The latter signals, which allow us to determine where we are being touched, are conducted by nerves that have a fatty sheath of myelin that insulates the nerve. Nerves with a thick layer of myelin conduct signals more rapidly than unmyelinated nerves. In contrast, the signalling of pain in humans has been thought to be considerably slower and carried out by nerves that have only a thin layer of myelin, or none at all.
In monkeys and many other mammals, on the other hand, part of the pain-signalling system can conduct nerve signals just as fast as the system that signals touch. The scientists speculated whether such a system is also present in humans.
"The ability to feel pain is vital to our survival, so why should our pain-signalling system be so much slower than the system used for touch, and so much slower than it could be?" asks the author.
To answer this, the scientists used a technique that allowed them to detect the signals in the nerve fibres from a single nerve cell. They examined 100 healthy volunteers and looked for nerve cells that conducted signals as rapidly as the nerve cells that detect touch, but that had the properties of pain receptors, otherwise known as nociceptors. Pain receptors are characterised by the ability to detect noxious stimuli, such as pinching and abrasion of the skin, while not reacting to light touch. The researchers found that 12% of thickly myelinated nerve cells had the same properties as pain receptors, and in these nerve cells the conduction speed was as high as in touch-sensitive nerve cells.
The next step of the scientists' research was to determine the function of these ultrafast pain receptors. By applying short electrical pulses through the measurement electrodes, they could stimulate individual nerve cells. The volunteers described that they experienced sharp or pinprick pain.
"When we activated an individual nerve cell, it caused a perception of pain, so we conclude that these nerve cells are connected to pain centres in the brain", says another author.
The research team also investigated patients with various rare neurological conditions. One group of people had, as adults, acquired nerve damage that led to the thickly myelinated nerve fibres being destroyed, while the small fibres were spared. These patients cannot detect light touch. The scientists predicted that the loss of myelinated nerve fibres should also affect the rapidly conducting pain system they had identified. It turned out that these people had an impaired ability to experience mechanical pain. Examination of patients with two other rare neurological conditions gave similar results. These results may be highly significant for pain research, and for the diagnosis and care of patients with pain.
"It's becoming evident that thickly myelinated nerve fibres contribute to the experience of pain when it has a mechanical cause. Our results challenge the textbook description of a rapid system for signalling touch and a slower system for signalling pain. We suggest that pain can be signalled just as rapidly as touch", says the author.
https://liu.se/en/news-item/smartsignalering-hos-manniska-snabbare-an-man-trott
https://advances.sciencemag.org/content/5/7/eaaw1297 f
Latest News
Chromatin and RNA interacti…
By newseditor
Posted 18 May
Why patients with ARID1A mu…
By newseditor
Posted 18 May
Smuggling small molecule mo…
By newseditor
Posted 18 May
Men with gene mutations are…
By newseditor
Posted 17 May
B cell oxidative phosphoryl…
By newseditor
Posted 17 May
Other Top Stories
An immune cell enzyme in the defense against tuberculosis
Read more
Protocadherin-1is an hantavirus receptor
Read more
Sugar and microbiome in mother's milk influences neonatal rotavirus…
Read more
How antibiotics help spread resistance
Read more
A new mechanism to increase Trypanosoma parasite virulence
Read more
Protocols
Breast cancer-on-chip for p…
By newseditor
Posted 16 May
Methods for making and obse…
By newseditor
Posted 15 May
Mime-seq 2.0: a method to s…
By newseditor
Posted 13 May
Improved detection of DNA r…
By newseditor
Posted 09 May
Single-cell adhesive profil…
By newseditor
Posted 07 May
Publications
Immunotherapy for colorecta…
By newseditor
Posted 18 May
Single-cell multiplex chrom…
By newseditor
Posted 18 May
Autophagy preferentially de…
By newseditor
Posted 18 May
Poison Ivy, Poison Oak, and…
By newseditor
Posted 18 May
GLP-1-directed NMDA recepto…
By newseditor
Posted 18 May
Presentations
Hydrogels in Drug Delivery
By newseditor
Posted 12 Apr
Lipids
By newseditor
Posted 31 Dec
Cell biology of carbohydrat…
By newseditor
Posted 29 Nov
RNA interference (RNAi)
By newseditor
Posted 23 Oct
RNA structure and functions
By newseditor
Posted 19 Oct
Posters
A chemical biology/modular…
By newseditor
Posted 22 Aug
Single-molecule covalent ma…
By newseditor
Posted 04 Jul
ASCO-2020-HEALTH SERVICES R…
By newseditor
Posted 23 Mar
ASCO-2020-HEAD AND NECK CANCER
By newseditor
Posted 23 Mar
ASCO-2020-GENITOURINARY CAN…
By newseditor
Posted 23 Mar