Nppb Neurons Are Sensors Of Mast Cell-Induced Itch

Itch is an unpleasant skin sensation which can be triggered by exposure to many chemicals including those released by mast cells. The Nppb-expressing class of sensory neurons when activated elicit scratching responses in mice, however, it is unclear which itch-inducing agents stimulate these cells and the receptors involved. Here, we identify receptors expressed by Nppb-neurons and demonstrate the functional importance of these receptors as sensors of endogenous pruritogens released by mast cells. Our search for receptors in Nppb-neurons revealed that they express leukotriene, serotonin, and sphingosine-1-phosphate receptors. Targeted cell ablation, calcium imaging of primary sensory neurons, and conditional receptor knockout studies demonstrate that these receptors induce itch by the direct stimulation of Nppb-neurons and neurotransmission through the canonical GRP-dependent spinal cord itch pathway. Together our results define a molecular and cellular pathway for mast cell-induced itch. Examination of transcriptome (RNA-seq) of 2 different populations of DRG neurons in quadruplicates.