How do we feel pain?
Researchers have now identified a new organ involved in the sensation of pain. This can lead to the development of effective new analgesic drugs.
The current Karolinska Institutet investigation in Stockholm found that special cells in the outer layer of the skin are involved in the perception of pain. The results of the study were published in the English journal Science.
Do pain-sensitive cells spread in the outer skin layer?
Researchers have found that special cells surrounding the pain-sensitive nerve cells that extend into the outer layer of the skin appear to be involved in the perception of pain. The findings give new insights into the perception of pain that could help answer long-standing questions about pain, the researchers said. The cells mentioned above are a type of so-called Schwann cell that wraps nerve cells to keep them alive. The researchers found that these Schwann cells have appendages that wrap around the edges of pain-sensitive nerve cells that extend into the epidermis, the outer layer of the skin.
Are our nerve endings unprotected?
The ends of nerve cells in the epidermis have long been thought to be open or unprotected. Therefore, the new results were quite surprising to researchers. In the area of pain, there is often talk of loose nerve endings that are responsible for the sensation of pain. In fact, nerve endings are not free, the research group explains.
The experiment was performed on mice
The team's biggest finding was that Schwann's cells could feel pain. The discovery was made using so-called optogenetics, in which mice were genetically engineered so that Schwann cells in the skin of their feet produce a protein that can absorb light. When light falls on these cells, this protein changes, affects the membrane and causes the electric charge of the cells to shift. In other words, cells are stimulated. When the light fell on the cells, the mice lifted their feet. They also showed behaviors such as licking, shaking and protecting the paws. There is every indication that stimulation of these Schwann cells causes pain. As the duration of the light pulses increases, the number of nearby nerve cells increases, supporting the belief that these Schwann cells send a signal to the brain through nerve cells. To find out what else could activate Schwann's cells, the team exposed the mice's feet to heat, cold, and forceps. They then compare behavior with animal responses when light is used to easily activate, sensitize, or deactivate Schwann cells.
A new organ for the sensation of pain found?
The results show that mice exhibit a stronger pain response after cells are activated by light. This indicates that Schwann's special cells are important for pain detection, the researchers said. With Schwann's special cells and nerves engulfing them in a mesh-like network, researchers have basically found a new pain-sensitive organ. This is a type of two-cell receptor organ: it involves the nerve and the Schwann cell. Now research must continue on humans. (As)
- Hind Abdo, Laura Calvo-Enrique, Jose Martinez Lopez, Jianren Song, Ming-Dong Zhang et al .: Schwann Specialized Skin Cells Initiate Sensation of Pain, in Science (Request: 08/16/2019), Science