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Updated: Jul 5, 2026

Mechanical Conflict-Avoidance Assay to Measure Pain Behavior in Mice
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Mechanical Conflict-Avoidance Assay to Measure Pain Behavior in Mice

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Fast-conducting mechanonociceptors uniquely engage reflexive and affective pain circuitry to drive protective

Karina Lezgiyeva1, Jingyi Liu1, Karen Nguyen1

  • 1Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.

Neuron
|July 3, 2026
PubMed

Insights

Researchers identified specific nociceptor populations, Smr2Cre- and Bmpr1bCre-labeled Aδ high-threshold mechanoreceptors (HTMRs), that detect damaging stimuli and trigger pain responses. These findings offer new targets for developing pain-relieving drugs.

Area of Science:

  • Neuroscience
  • Pain Research
  • Sensory Biology

Background:

  • Nociceptors are crucial for detecting harmful stimuli and initiating pain responses.
  • Understanding specific nociceptor subtypes is key to developing targeted pain therapies.

Purpose of the Study:

  • To identify genetically defined nociceptor populations responsible for pain behaviors using optogenetics.
  • To investigate the physiological, morphological, functional, and synaptic properties of identified nociceptor subtypes.

Main Methods:

  • Optogenetic activation screen to identify nociceptor populations.
  • Electrophysiology, morphology, and in vivo behavioral analysis.
  • Spinal cord slice electrophysiology to study synaptic connections.

Main Results:

  • Smr2Cre- and Bmpr1bCre-labeled Aδ high-threshold mechanoreceptors (HTMRs) were identified as key nociceptors.
  • Aδ-HTMRs are activated by intense mechanical stimuli and are essential for protective withdrawal reflexes.
  • These neurons form direct synaptic connections with spinal cord projection neurons involved in pain signaling.

Conclusions:

  • Aδ-HTMRs are a distinct class of myelinated nociceptors with unique properties.
  • Their specific activation and projection patterns suggest a critical role in acute mechanical pain.
  • Targeting Aδ-HTMRs presents a promising avenue for novel analgesic development.
Keywords:
antenna cellsanterolateral tractfast mechanical painmechanosensationmyelinated nociceptorspainsomatosensation

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