American researchers have just explained the organic phenomenon at the origin of this well-known observation: the more we scratch, the more we want to scratch.
Moms are always right, it seems… “Stop scratching, it will get worse!” We often hear them say. And on this point, we must recognize their clairvoyance. A study published in the journal Neuron confirms this strange phenomenon: the more you scratch, the more you want to scratch.
Micro-lesions on our skin
The reason is quite simple. When we feel an itch, we end it by rubbing our fingernails frantically on the affected body part and thus creating tiny lesions on our skin. Purpose of the maneuver: to bypass the itching nerve signals, and replace them with pain messages – very relative, of course. Some people choose to hit the itchy areas with the flat of their hands, instead of scratching them.
The technique works… for a few seconds anyway. In fact, in the spinal cord, for a very short period of time, the nerve cells interpret the pain signals and silence the itching signals. And we have to admit it, it feels really good.
Itching and pain signals – Credit: Mark Hoon
When serotonin goes the wrong way
“The problem is, the brain responds to these messages by producing serotonin to help it control pain,” says Zhou-Feng Chen, a researcher at the University’s Center for the Study of Itch (truthful). of Washington, and director of the study. However, we have discovered that when serotonin diffuses into the spinal cord, it can “go wrong”. Instead of reaching the pain neurons, she wakes up itchy nerve cells “.
For the purposes of the study, the researchers thus selected a species of mouse that lack the genes responsible for the production of serotonin. They injected these genetically modified mice with a hives solution. Result: the latter scratched very little, compared to “normal” mice. On the other hand, by injecting them with serotonin, they began to scratch like the others.
Mouse scratches frantically, after injection of urticaria substance – Center for the Study of Itching, University of Washington
Vicious circle
“We have searched for a long time for the reasons for this vicious cycle of itching. Our research suggests that events are happening in this direction. First, you scratch yourself, and that creates a form of pain. Then the brain produces serotonin, which will stimulate the nerve cells to itch. And so on. It also shows that the itch and pain signals are transmitted by different, but connected paths, ”continues the researcher.
We now understand why itching sometimes turns into obsession … But scientists do not offer a specific remedy. On the contrary, they urge not to use their results to develop a treatment that lowers serotonin levels. “This could have bad long-term consequences – seronotin is involved in growth, bone metabolism, mood regulation… And we would be deprived of this natural painkiller! “
Consult our Itching and Pruritus health sheet
The Vicious Cycle of Itch – Center for the Study of Itch, University of Washington
Grandmother’s remedy
Recently, a German study tested the effectiveness of an original technique to relieve urticaria sensations. It consists of scratching in front of … a mirror. For example, if your right arm is itchy, you should scratch your left arm in front of a mirror. Because, according to the study, visual signals take precedence over information transmitted from the body to the brain. Disrupting his nervous messages, quite an art!
Moreover, part of the itching sensation is neither chemical nor organic, but psychological, according to many dermatologists. Of course, this applies to non-pathological itching. In these cases, then, the shot of the mirror can therefore work perfectly. By the way … how many times have you scratched yourself while reading this article?
.
-1685098342.jpg "Her itching between her toes was actually skin cancer")
