Work

Identification of a convergent spinal neuron population that encodes itch

Year: 2023

Type: preprint

Abstract: Summary Itch is a protective sensation that drives scratching. Although specific cell types have been proposed to underlie itch, the neural circuit basis for itch remains unclear. Here, we used two-photon Ca 2+ imaging of the dorsal horn to visualize the neuronal populations that are activated by itch-inducing agents. We identify a convergent population of spinal neurons that is defined by the expression of GRPR. Moreover, we discover that itch is conveyed to the brain via GRPR-expressing spinal output neurons that target the lateral parabrachial nucleus. Further, we show that nalfurafine, a clinically effective kappa opioid receptor agonist, relieves itch by inhibiting GRPR spinoparabrachial neurons. Finally, we demonstrate that a subset of GRPR spinal neurons show persistent, cell-intrinsic Ca 2+ oscillations. These experiments provide the first population-level view of the spinal neurons that respond to pruritic stimuli, pinpoint the output neurons that convey itch to the brain, and identify the cellular target of kappa opioid receptor agonists for the inhibition of itch. In brief Through population imaging, Sheahan et al. identify a network of neurons in the dorsal horn that is activated by pruritogens and find that kappa opioid receptor signaling inhibits itch through the selective inhibition of GRPR spinoparabrachial neurons. Highlights Itch-inducing agents drive activity in a common population of GRPR-expressing spinal interneurons GRPR spinal projection neurons transmit itch from the spinal cord to the brain Kappa opioids reduce itch through the inhibition of GRPR spinoparabrachial neurons GRPR activation elicits persistent, intrinsic Ca 2+ oscillations

Source: bioRxiv (Cold Spring Harbor Laboratory)

DOI: 10.1101/2023.09.29.560205