2007年VOA慢速英语special200708010041

This is the VOA Special English Health Report.

Itchy skin is a common problem. Severe itching 2 can interfere 3 with sleep or lead to
Scratching an itch 1

painful damage from scratching. Now, scientists may have a way to develop new treatments for severe itching.

They report finding a gene 4 that sends the itch signal up the spinal 5 cord to the brain. This is the first gene identified for the itch sensation in the central nervous system.

A team led by Zhou-Feng Chen at Washington University School of Medicine in Saint Louis, Missouri, made the discovery in mice. The study appeared last week in the journal Nature.

The gene is called GRPR, for gastrin-releasing peptide receptor. This gene has been studied for years, but scientists did not know it was linked to itching. The Washington University researchers say they discovered the connection by accident while searching for genes 6 linked to pain.

During their experiments, they gave itch-causing substances to some laboratory mice. They found that mice without the GRPR gene scratched much less than normal mice with the gene. However, the animals reacted to pain in the same way as normal mice.

The scientists say the reaction showed that pain and itch are controlled by separate sets of genes in the spinal cord.

Because the mice without the itch gene did scratch a little, scientists believe there must be other itch genes in the body.

Still, the discovery is seen as good news for people who have severe dry skin or other conditions that cause itching. These include skin disorders 7 like eczema and problems such as kidney failure or liver disease. The researchers, though, have not confirmed whether the GRPR gene is involved in these diseases.

Cancer treatments and strong painkillers 8 like morphine can also cause itchiness.

Yet effective treatments for severe itching are limited. This is partly because scientists have traditionally thought that an itch was a less intense form of pain. Because of this, Professor Chen says itch research has lived in the shadow of pain research.

He notes that many genes have been identified along the pain pathway. Now the discovery of a so-called itch gene could lead to new treatments for people who suffer from severe itching. The researchers suggest that new drugs could be developed to suppress itching without affecting a person's ability to sense pain.

And that's the VOA Special English Health Report was written by Brianna Blake. For more health news, along with transcripts 9 and archives of our reports, go to www.unsv.com. I'm Steve Ember.