Researchers identify itch specific cells in mice

A team of international researchers have identified a group of neurons in mice that control their responses to itching sensations.

Zhou-Feng Chen and his colleagues at the Washington University School of Medicine in St. Louis injected the spinal cords of mice with a neurotoxin called bombesin-saporin.

The injection led to the suppression of the cells in which the specific gene called GRPR (gastrin-releasing peptide receptor) was active in neurons found in the spinal cord.

Observations by scientists
When the mice were exposed to things that caused itching, they didn't scratch. The researchers stated that with an appropriate dose of the neurotoxin, their scratching could be reduced by more than 80 percent or completely eliminated in some instances.

However, the scientists noted that the mice still reacted to pain. This put to rest the general assumption that scratching was simply a less intense version of pain.

Dr Zhou-Feng Chen said: "This finding has very important therapeutic implications. We have shown that particular neurons are critical for the itching sensation but not for pain, which means those cells may contain several itch-specific receptors or signaling molecules that can be explored or identified as targets for future treatment or management of chronic itching."

Two types of itching
Scientists state that there are two types of itching. One is an outcome of allergic reactions, linked to the presence of the chemical histamine. However, the severe itching does not respond to standard anti-histamine treatment.

The interesting part of the study was that the mice whose itch cells had been killed did not scratch, irrespective of the type of itching they were exposed to.

Study important for future treatment in itching
According to Chen, “Mice are one of the best models for itching, because so far we have found that all substances which can cause itching sensations in humans can also cause scratching behaviors in mice."

He further stated that the work is important and would help focus on the cells and their composition, paving the way for treatment of serious human itches, such as psoriasis and eczema.

The research was published in the Aug. 6 issue of Science Express, the advance online publication of the journal Science.