Cause of uncontrollable chronic itching uncovered

Teresa Tanoos's picture
Researchers say chronic itching may be caused by pain neurons.
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If you have ever suffered through sleepless nights due to uncontrollable itching, you know how excruciating it can be, and that not all itching is the same. Chronic itching, which can occur in medical conditions ranging from eczema and psoriasis to kidney failure and liver disease, is very different from the temporary urge to scratch after a mosquito bite - and now researchers say they have uncovered the reasons why.

In addition to nerve cells (neurons), which transmit itch signals, American and Chinese researchers say that chronic itching also employs pain neurons that intensify the itchy sensation. In other words, chronic itching appears to include more than just the nerve cells, or neurons, that usually transmit itch signals. In chronic itching, neurons that send itch signals also incorporate pain neurons to intensify the urge to itch.

In a study, published in The Journal of Clinical Investigation, the researchers created genetically modified mice that had a continuously active protein called BRAF transmitting signals inside itch neurons. Both the BRAF gene and the protein play a role in how the body responds to pain, although it remains unclear as to whether the BRAF gene plays a role in the response to itch.

After the researchers created the genetically modified mice, they were shocked to discover that they had developed a chronic itch mouse model, with the BRAF protein having the ability to switch many itch genes on and off.

"We thought the animals might be prone to feeling pain rather than itching," said Dr. Zhou-Feng Chen, director of Washington University's Center for the Study of Itch. "To our great surprise, the mice scratched spontaneously. At first, we didn't know why they were scratching, but it turns out we developed a mouse model of chronic itch."

These findings demonstrated that when the mice experienced chronic itch triggered by dry skin from an allergic rash, the itch genes similarly changed as a result of the BRAF protein control, which the researchers say may explain why chronic itching can be so incessant in comparison to the fleeting itch from a bug bite or some other skin condition.

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“In normal itching, there's a fixed pathway that transmits the itch signal,” explained Dr. Chen. “But with chronic itching, many neurons can be turned into itch neurons, including those that typically transmit pain signals. That helps explain why chronic itching can be so excruciating.”

By the same token, the researchers pointed out that the genetically modified mice expressed a normal response to pain, an indication that there are significant differences in the pain and itch pathways. As a result of these findings, the possibility exists for developing new treatments for chronic itch by targeting proteins that are present in the BRAF pathway.

According to Dr. Chen, one such possibility that could be explored is through using drugs that are able to treat pain, especially given that there are certain drugs in existence that inhibit some of the same targets in patients suffering from chronic pain; thus, these could also be used to provide relief for itching.

However, Chen said that the findings of this study offer many more options for potential chronic itch treatments.

“In people, chronic itching can last for weeks, months, or even years. These mice are helping us to understand the pathways that can be involved in transmitting itch signals and the many contributors to chronic itching," said Chen.

“There are many pathways leading from BRAF, and all of these could be potential targets for anti-itch therapies.”

SOURCES: Chronic itch development in sensory neurons requires BRAF signaling pathways, Zhong-Qiu Zhao, Fu-Quan Huo, Joseph Jeffry, Lori Hampton, Shadmehr Demehri, Seungil Kim, Xian-Yu Liu, Devin M. Barry, Li Wan, Zhong-Chun Liu, Hui Li, Ahu Turkoz, Kaijie Ma, Lynn A. Cornelius, Raphael Kopan, James F. Battey, Jr., Jian Zhong, Zhou-Feng Chen, published in the Journal of Clinical Investigation, October 8, 2013.

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Comments

I think I might have chronic itching what should I do ?
What kind of doctor do I need to see for this chronic itching?
i am a 57 year old woman and my Son just turned 19 a few days ago we both have SEVERE CHRONIC ITCHING and he so needs help!I am scared for his mental health he is on his way to a job interview and he is itching so bad that he said one more day of this itching and Death would be better.We live in the Chattanooga Tn area and cannot find anyone who can help!They think it is allergies but we know better everytime we get a little stressed the Crazy itching starts and my common sense tells me this is not allergies we get splotchy on our face and neck claw and draw blood!I am so concered for my Son mental health what do you suggest we do he has triedHydroxyzine does not help cetirizine nothing works oh and allergy shots Please any suggestions Thanks Audrey and good luck on you research!:)
I have it, usually when stressed. I have found that icing it until numb works. It seems to not come back, at least right away, after icing.
I have an itch on my chest, back, legs, arms and all over. I do not want to see another dermatologist in my life. It's been several years since this started and many, many visits to dermatology doctors. Thousands of dollars spent for nothing. Just recently I ordered some frankincense essential oil that came with myrrh oil, and I decided to try it on my itchy skin. It seems to be working somewhat. I only used it 3 times so far and I feel some relive. I mix the 2 oils in a table spoon of organic, unrefined coconut oil and the massage it on my skin. One time I used just the oils alone. Its worth to give it a try. Good luck to you and your son.
I am trying to find a cause of/treatment for my mom's chronic itching. It began after a high dosage of augmenten and, now a month later, has not stopped. It could also be stress related.....open to any suggestions at this point. She is going crazy :(As Audrey Sheldon mentioned regarding her son, hydroxyzine has not helped, nor has prednisone. Does anyone have any ideas? Her physician does not seem to be as concerned as I would like him to be.
I suffer as well and would really appreciate any advice as to what type of doctor I should visit. I've been to many dermatologists that cure the immediate rash/sores/ infection but then the uncontrollable itch returns. It has effected me emotionally and makes it very difficult to concentrate at work. I am begging for help.
i have itching problem for several years. just discovered remendy, i hope. been using it for a week and had great results from the first night i used it. slept all night without itching. i put one tabel spoon of crushed red pepper into one cup of water. boiled water for about ten or fifteen minutes then let it set to cool down. strained the red pepper from the water and applied the reddish colored water to the ara of severe itching and it helped immediately. used it for another 4 or 5 days until that spot was finished itching. let me know if this helps you. tom. [email protected]
Please help. Haven't slept in days. I do have chronic 3rd stage kidney disease. Also psoriatic arthritis and, under achieving thyroid.
My mom suffers from chronic itching. It is driving her nuts. We tried everything for relief. We know that she has low kidney function and she also has a pace maker for her heart. What can we do?
I can't take it anymore! It's driving me insane! I have scratched my scalp,back,arms,legs raw on my face also. Not only itching but especially on my face it turns into lumps where it looks like I have been beaten up. I have been on so many courses of steroids that my GP wrote a script so I have it on hand. It's even affected my tongue and throat where it's closing up. Can anyone help? I'm so desperate!
The fact that you're having throat swelling needs immediately medical attention .don't delay