|Scientists Discover 'Itch' Molecule|
|By SYDNEY LUPKIN (@slupkin)||May 24, 2013, 4:37 PM|
Scientists have discovered the molecule responsible for causing itchiness, but they can't scratch the problem off their lists just yet.
Researchers at the National Institutes of Health identified the itch molecule in mice and found that by using drugs to block the molecule, the mice didn't scratch when presented with itchy stimuli -- a skin irritant and a malaria drug known to cause itchiness.
"It's such a common problem and can be really devastating for quite a number of patients," said Dr. Jennifer Stein, a dermatology professor at NYU Langone Medical Center. "There are so many different choices of pain medicine for people, but we really have very limited treatments for itch."
Although most people only associate itch with bug bites and allergies, it can also be caused by other health problems such as thyroid disease and rare cases of lymphoma, Stein said.
Although antihistamine drugs are often used to stop itch, they don't work for all itches. And once a patient starts scratching, the itch often gets worse and turns into a cyclical problem.
The molecule is called natriuretic polypeptide b -- or Nppb – and it works by "plugging" into a nerve cell in the spinal cord to send a message to the rest of the central nervous system that's later experienced in the brain as an itch. The research paper was published in the journal Science on Friday.
"When we exposed the Nppb-deficient mice to several itch-inducing substances, it was amazing to watch." said Santosh Mishra, lead author on the study. "Nothing happened. The mice wouldn't scratch."
Although this isn't the first itch research to be published, it seems to indicate a start switch to the complex series of events involved in creating the itch sensation.
Scientists had previously found another neurotransmitter responsible for itch called GRP. Mishra and her colleagues learned that still applies, but GRP enters the process after Nppb, according to an NIH press release.
Only more research will show whether Nppb has the same function in humans, said Xinzhong Dong, an itch expert and professor of neuroscience at Johns Hopkins School of Medicine.
"Basically, they laid out a good foundation," Dong said. "Any medical research is still a long way to go to really come up with a workable drug to block this peptide and mitigate itch transmission."