Researchers have discovered the protein essential to the itch response, at least in mice. Identifying the neural circuits differentiates the itching sensation from the pain
Until recently, researchers believed that itching was a low degree of pain. A new study disagrees with this approach and shows that there are differences between the feeling of itching and pain, when itching is responsible for a neural circuit that connects the cells in the periphery of the body to the brain. This is according to a study conducted in mice.
Neuroscientists Mark Hun and Santosh Mishra from the National Institute of Dental, Head and Skull Research in Bethesda, Maryland searched for the molecule that encodes the itch sensation by scanning genes in neurons used to sense touch, heat, pain and itch. They discovered a certain protein known as natriuretic polypeptide b or Nppb for short, it is responsible for expression only in a subset of these neurons.
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Mutant mice lacking Nppb did not respond to compounds that cause itching, but responded normally to heat and pain. The researchers also found that when they injected Nppb into the necks of these mice they went into a frenzy of self-scratching. The phenomenon occurred both in the mutant mice and in the control group.
"Our study revealed the transmitter used by the neurons used to sense itch, confirming that the itch was detected by specialized neurons," Hoon says.
The two went on to look for neurons with Nppb receptors in the spinal cord. They injected a toxin made from soapwort seeds targeting these neurons in the spinal column and they blocked responses to itch, but not other sensory responses, suggesting that information about the itch sensation is transmitted along a clear pathway.
goals for treatment
"The results explain problems in the scientific literature and provide a testable prediction of how the itch mechanism works," says Glenn Geisler, a neuroscientist at the University of Minnesota in Minneapolis.
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Previous studies led researchers to hypothesize that gastrin-releasing peptides (GRP) were the neurotransmitter that frees sensory nerves to initiate itch-related signals. However, Hon and Mishra, and another group of researchers were unable to find GRP outside the spine, indicating that GRP is not the main driver.
However, the two discovered that GRP is still involved in the itch response. Injection of GRP into mice lacking Nppb or its receptor caused them to produce an itch response. Also, mice whose GRP receptors were inhibited did not engage in scratching behavior, even when injected with Nppb spinally. These results implicate the GRP-related neurons below the Nppb in the transmission of the itch sensation.
The neural pathways for itch in humans are similar, but not identical, to those in mice, and it is still not clear whether they involve Nppb or something similar. Hoon says they plan to conduct follow-up tests in humans later.
According to Geisler, itching is a common problem, and is associated with over 20 different conditions, including eczema and psoriasis. "Antihistamines only work on a few forms of itching, but on most types of itching they have no effect at all," he added. This research provides us with a new target for medical treatments.
And another matter related to itching - The genome of the toenail fungus and dozens of other types of fungi that live on the skin roars
One response
So, in psoriasis, the same nppb receptor material in combination is stimulated in an increased way by the illuminating alternative of the cells (the accelerated alternative) and thus the same neurons in the spinal column transmit to the brain that the same area itches.