Scientists from University College London and Germany's Saar University have found that people with congenital insensitivity to pain also do not smell. Researchers believe that the same channel in the brain is responsible for the sense of pain and smell.
The participants in the experiment were three people with mutations in a protein known as the Nav1.7 ion channel. Researchers were studying their characteristics when they unexpectedly discovered that all three had no sense of smell. According to one of the scientists, this discovery has become completely unpredictable.
Subjects could not smell any odors, even the harshest, sophisticated, and widespread, although all three lead relatively normal lives. To find out how Nav1.7 might have to do with smell, an experiment was conducted in mice. As a result, it turned out that in both humans and mice, this ion channel serves as an interpreter between the cells in the nose, which pick up the smell, and the cells in the brain, which recognize it.
Potassium ions move along the channel across the membrane of a brain cell, where they come into contact with another brain cell. This point of contact is called a synapse. The receptors in the nose in such people continue to work, but the signal does not go to the brain because the ion channel is not functioning.
Since there is a close relationship between smell and taste, it is also possible that people who do not feel pain do not distinguish between tastes. The same channel, Nav1.7, is responsible for transmitting signals from taste buds to the brain. The likelihood of such people not having a sense of taste is very high, but such a study has not yet been conducted.