A subset of spinal dorsal horn interneurons crucial for gating touch-evoked pain-like behavior

Ryoichi Tashima, Keisuke Koga, Yu Yoshikawa, Misuzu Sekine, Moeka Watanabe, Hidetoshi Tozaki-Saitoh, Hidemasa Furue, Toshiharu Yasaka, Makoto Tsuda

Research output: Contribution to journalArticlepeer-review

Abstract

A cardinal, intractable symptom of neuropathic pain is mechanical allodynia, pain caused by innocuous stimuli via low-threshold mechanoreceptors such as Aβ fibers. However, the mechanism by which Aβ fiber-derived signals are converted to pain remains incompletely understood. Here we identify a subset of inhibitory interneurons in the spinal dorsal horn (SDH) operated by adeno-associated viral vectors incorporating a neuropeptide Y promoter (AAV-NpyP+) and show that specific ablation or silencing of AAV-NpyP+ SDH interneurons converted touch-sensing Aβ fiber-derived signals to morphine-resistant pain-like behavioral responses. AAV-NpyP+ neurons received excitatory inputs from Aβ fibers and transmitted inhibitory GABA signals to lamina I neurons projecting to the brain. In a model of neuropathic pain developed by peripheral nerve injury, AAV-NpyP+ neurons exhibited deeper resting membrane potentials, and their excitation by Aβ fibers was impaired. Conversely, chemogenetic activation of AAV-NpyP+ neurons in nerve-injured rats reversed Aβ fiber-derived neuropathic pain-like behavior that was shown to be morphine-resistant and reduced pathological neuronal activation of superficial SDH including lamina I. These findings suggest that identified inhibitory SDH interneurons that act as a critical brake on conversion of touch-sensing Aβ fiber signals into pain-like behavioral responses. Thus, enhancing activity of these neurons may offer a novel strategy for treating neuropathic allodynia.

Original languageEnglish
Article numbere2021220118
JournalProceedings of the National Academy of Sciences of the United States of America
Volume118
Issue number3
DOIs
Publication statusPublished - Jan 19 2021

All Science Journal Classification (ASJC) codes

  • General

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