Inputs to the locus coeruleus from the periaqueductal gray and rostroventral medulla shape opioid-mediated descending pain modulation

Sci Adv. 2024 Apr 26;10(17):eadj9581. doi: 10.1126/sciadv.adj9581. Epub 2024 Apr 26.

Abstract

The supraspinal descending pain modulatory system (DPMS) shapes pain perception via monoaminergic modulation of sensory information in the spinal cord. However, the role and synaptic mechanisms of descending noradrenergic signaling remain unclear. Here, we establish that noradrenergic neurons of the locus coeruleus (LC) are essential for supraspinal opioid antinociception. While much previous work has emphasized the role of descending serotonergic pathways, we find that opioid antinociception is primarily driven by excitatory output from the ventrolateral periaqueductal gray (vlPAG) to the LC. Furthermore, we identify a previously unknown opioid-sensitive inhibitory input from the rostroventromedial medulla (RVM), the suppression of which disinhibits LC neurons to drive spinal noradrenergic antinociception. We describe pain-related activity throughout this circuit and report the presence of prominent bifurcating outputs from the vlPAG to the LC and the RVM. Our findings substantially revise current models of the DPMS and establish a supraspinal antinociceptive pathway that may contribute to multiple forms of descending pain modulation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adrenergic Neurons / drug effects
  • Adrenergic Neurons / metabolism
  • Analgesics, Opioid* / pharmacology
  • Animals
  • Locus Coeruleus* / drug effects
  • Locus Coeruleus* / metabolism
  • Male
  • Medulla Oblongata* / drug effects
  • Medulla Oblongata* / metabolism
  • Mice
  • Neural Pathways / drug effects
  • Pain* / drug therapy
  • Pain* / metabolism
  • Periaqueductal Gray* / drug effects
  • Periaqueductal Gray* / metabolism

Substances

  • Analgesics, Opioid