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Two Studies Focus in on the Intricacies of Mechanical Allodynia

A better look at the Piezo2 ion channel, an important aspect of touch sensation.

A PPM Brief

The results of two studies1,2 have led to new understandings of sensory neurons and mechanical allodynia (registering light touches as painful), following injury in mice and humans. While distinct subsets of sensory neurons can distinguish between sensations such as a light feather or the prick of a thorn, inflammation, nerve injury, and trauma can affect these sensations, causing small touches to become intensely painful. By identifying an ion channel involved in sensory neuron signaling as a culprit for this hypersensitivity to pain, the studies could lead to new therapeutic strategies.

In the first study,1 Swetha Murthy, PhD, from the department of neuroscience at the Scripps Research Institute in La Jolla, CA, and colleagues zeroed in on the function of the Piezo2 ion channel, which has previously been shown to play a key role in touch sensation. Activating Piezo2-expressing neurons was shown to induce pain sensations in mice, discovering that rodents deficient in Piezo2 did not register pain in response to soft touches in several models of mechanical allodynia.

Distinct subsets of sensory neurons can distinguish between sensations such as a light feather or the prick of a thornDistinct subsets of sensory neurons can distinguish between sensations such as a light feather or the prick of a thorn. (Source: 123RF)

In a second study,2 Marcin Szczot, PhD, from the National Center for Complementary and Integrative Health at the National Institute of Health in Bethesda, MD and colleagues used imaging techniques to study sensory neurons in mice. Piezo2 was necessary for responses to gentle mechanical stimuli (such as air puffs and vibration), but not normal pain sensation. By studying four individuals with mutations resulting in a loss of Piezo2 function, they found that they did not perceive light brushes as painful when applied to an inflamed spot on the forearm, indicating that blocking Piezo2 function could potentially prevent allodynia without affecting normal pain responses.

Mechanical allodynia is a major concern for pain clinicians and researchers alike, and further investigation is needed to determine the contributors that distort pain perception at the molecular level.

Last updated on: November 1, 2018
Continue Reading:
Assessment and Treatment of Neuropathic Pain
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