Understanding neural mechanisms of mechanical itch

Article Dermatology

Increased touch-evoked itch (punctate hyperknesis) in postherpetic itch: Implications of reduced intraepidermal nerve fibers representing small fiber neuropathy

Takashi Hashimoto et al.

Summary: This study reported five patients with postherpetic itch, showing increased touch-evoked itch in the affected skin areas. Skin biopsy specimens from two patients revealed reduced intraepidermal nerve fibers in the affected skin areas. In one case, improvement in itching and comparable levels of touch-evoked itch were observed after 6 months without medication, along with restored intraepidermal nerve fibers confirmed through rebiopsy. Reduced intraepidermal nerve fibers may contribute to postherpetic itch and its associated punctate hyperknesis.

JOURNAL OF DERMATOLOGY (2023)

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Article Multidisciplinary Sciences

PIEZO1 transduces mechanical itch in mice

Rose Z. Hill et al.

Summary: This study reveals that the transduction of mechanical itch is mainly mediated by the ion channel PIEZO1. Loss of PIEZO1 function greatly reduces mechanically evoked scratching behaviors and acute/chronic itch sensitization. In addition, mice expressing a gain-of-function Piezo1 allele exhibit enhanced mechanical itch behaviors.

NATURE (2022)

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Article Cell Biology

Miswiring of Merkel cell and pruriceptive C fiber drives the itch-scratch cycle

Jing Feng et al.

Summary: This study reveals the mechanism behind the itch-scratch cycle in chronic itch. Mechanical stimulation of the skin activates Piezo2 channels on Merkel cells, leading to spontaneous itch in dry skin. The study also demonstrates structural alterations between pruriceptor nerve endings and Merkel cells in dry skin. These findings provide insights into the pathophysiology of chronic itch and may contribute to the development of new treatments.

SCIENCE TRANSLATIONAL MEDICINE (2022)

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Article Neurosciences

Molecular Determinants of Mechanical Itch Sensitization in Chronic Itch

Hankyu Lee et al.

Summary: Chronic itch is associated with sensitization of the somatosensory nervous system. This study found that Ucn3(+) neurons in a microcircuit showed increased excitability under chronic itch conditions, while NPY(+) neurons showed reduced excitability. Nav1.6 channels played a key role in the mechanical itch sensitization process.

FRONTIERS IN MOLECULAR NEUROSCIENCE (2022)

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Review Immunology