Purpose of review: To highlight the most recent advances regarding gastrointestinal peptides and their relation to chronic itch, with focus on gastrin-releasing peptide (GRP), substance P, and their respective receptors.
Recent findings: GRP and its high-affinity GRP receptor (GRPR) have been identified as key regulators in the spinal cord itch pathway and may be involved in the maintenance of chronic itch sensation. Several neuropeptides including GRP, neuromedin B, and substance P regulate itch signals in a cooperative or inhibitory manner on the spinal level. Small clinical studies show that neurokinin 1 receptor antagonists might be of benefit in the treatment of chronic itch.
Summary: Chronic itch is a burdensome clinical problem, for which no specific treatment is available. Studies on the mechanisms of pruriceptive sensation and its signaling to the central nervous system (CNS) via the spinal cord have elucidated a number of peptides that are implicated in the regulation of itch-specific signaling pathways. Among those, GRP and its high-affinity GRP receptor have been proposed as key elements in the itch-specific neuronal pathways.