Painful stimuli evoke a mixture of sensations, negative emotions and behaviors. These myriad effects are thought to be produced by parallel ascending circuits working in combination. Here we describe a pathway from spinal cord to brain for ongoing pain. Activation of a subset of spinal neurons expressing Tacr1 evokes a full repertoire of somatotopically-directed pain-related behaviors in the absence of noxious input. Tacr1 projection neurons (expressing NKR1) target a tiny cluster of neurons in the superior lateral parabrachial nucleus (PBN-SL). We showed that these neurons, which also express Tacr1 (PBN-SLTacr1), are responsive to sustained but not acute noxious stimuli. Activation of PBN-SLTacr1 neurons alone did not trigger pain responses but instead served to dramatically heighten nocifensive behaviors and suppress itch. Remarkably, mice with silenced PBN-SLTacr1 neurons ignored long-lasting noxious stimuli. Together, these data reveal new details about this spinoparabrachial pathway and its key role in the sensation of ongoing pain.
All data generated or analysed during this study are included in the manuscript and supporting files. Source data have been uploaded
- Alexander Theodore Chesler
- Ariel J Levine
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: Animal experimentation: All surgical, experimental and maintenance procedures were carried out in accordance in accordance with a protocol approved by the National Institute for Neurological Diseases and Stroke (NINDS) Animal Care and Use Committee (ASP1365 and ASP1369).
- Allan Basbaum, University of California San Francisco, United States
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.