Chronic lower limb pain is not associated with a loss of inhibitory neurons in the human lumbar spinal dorsal horn
- 1University of Texas at Dallas
Abstract
The spinal dorsal horn is the primary processing site of nociceptive sensory input from the periphery. Excitatory spinal interneurons releasing glutamate can amplify this information before it is sent to the brain, whereas inhibitory neurons releasing GABA and/or glycine can suppress the outflow of nociceptive signals. An imbalance favoring excitation is thought to underlie certain aspects of chronic pain. Although rodent studies have identified spinal mechanisms underlying hyperalgesia and allodynia, little is known about the anatomical changes associated with chronic pain in the human spinal cord, a gap in knowledge we sought to address in this study. Using immunohistochemistry and in situ hybridization on lumbar spinal cord tissue recovered from organ donors, we characterized neuronal size and density across the human dorsal horn and confirmed the presence of the human equivalent of the lateral spinal nucleus in many individuals. Chronic lower limb pain was not associated with changes in neuronal density in the dorsal horn. Likewise, the ratio of excitatory (SLC17A6+) to inhibitory (PAX2+) neurons remained consistent across laminae for age, sex and chronic pain state, providing no evidence for selective loss of inhibitory neurons with chronic pain in humans. We found no differences in the size or density of the postsynaptic markers Homer1 and gephyrin between groups, suggesting glutamatergic and GABAergic postsynaptic sites remain structurally stable. These findings provide a thorough evaluation of cellular anatomy of the human dorsal horn and form a foundation for future studies investigating neuronal changes that may contribute to chronic pain in humans.
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BibTeX
@misc{davis2026chronic,
title = {{Chronic lower limb pain is not associated with a loss of inhibitory neurons in the human lumbar spinal dorsal horn}},
author = {O. C. Davis and J. M. Brandon and K. Natarajan and L. He and Z. Khan and N. Selvakumaran and M. Babar and A. Alfayadh and S. I. Shiers and M. S. C. Yousuf and E. Vines and P. Horton and A. Cervantes and T. Khan and G. Funk and A. Todd and G. Dussor and T. J. Price},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.15.751829},
url = {https://www.biorxiv.org/content/10.64898/2026.09.15.751829v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Chronic lower limb pain is not associated with a loss of inhibitory neurons in the human lumbar spinal dorsal horn
AU - O. C. Davis
AU - J. M. Brandon
AU - K. Natarajan
AU - L. He
AU - Z. Khan
AU - N. Selvakumaran
AU - M. Babar
AU - A. Alfayadh
AU - S. I. Shiers
AU - M. S. C. Yousuf
AU - E. Vines
AU - P. Horton
AU - A. Cervantes
AU - T. Khan
AU - G. Funk
AU - A. Todd
AU - G. Dussor
AU - T. J. Price
PY - 2026
DA - 2026/09/15
PB - bioRxiv
DO - 10.64898/2026.09.15.751829
UR - https://www.biorxiv.org/content/10.64898/2026.09.15.751829v1
AB - The spinal dorsal horn is the primary processing site of nociceptive sensory input from the periphery. Excitatory spinal interneurons releasing glutamate can amplify this information before it is sent to the brain, whereas inhibitory neurons releasing GABA and/or glycine can suppress the outflow of nociceptive signals. An imbalance favoring excitation is thought to underlie certain aspects of chronic pain. Although rodent studies have identified spinal mechanisms underlying hyperalgesia and allodynia, little is known about the anatomical changes associated with chronic pain in the human spinal cord, a gap in knowledge we sought to address in this study. Using immunohistochemistry and in situ hybridization on lumbar spinal cord tissue recovered from organ donors, we characterized neuronal size and density across the human dorsal horn and confirmed the presence of the human equivalent of the lateral spinal nucleus in many individuals. Chronic lower limb pain was not associated with changes in neuronal density in the dorsal horn. Likewise, the ratio of excitatory (SLC17A6+) to inhibitory (PAX2+) neurons remained consistent across laminae for age, sex and chronic pain state, providing no evidence for selective loss of inhibitory neurons with chronic pain in humans. We found no differences in the size or density of the postsynaptic markers Homer1 and gephyrin between groups, suggesting glutamatergic and GABAergic postsynaptic sites remain structurally stable. These findings provide a thorough evaluation of cellular anatomy of the human dorsal horn and form a foundation for future studies investigating neuronal changes that may contribute to chronic pain in humans.
ER -