Chronic itch is a troublesome condition and often difficult to cure. Emerging evidence suggests that the periaqueductal gray (PAG)-rostral ventromedial medulla (RVM) pathway may play an important role in the regulation of itch, but the cellular organization and molecular mechanisms remain incompletely understood. Here, we report that a group of RVM neurons distinctively express the G-protein-coupled estrogen receptor (GPER), which mediates descending inhibition of itch. We found that GPER+ neurons in the RVM were activated in chronic itch conditions in rats and mice. Selective ablation or chemogenetic suppression of RVM GPER+ neurons resulted in mechanical alloknesis and increased scratching in response to pruritogens, whereas chemogenetic activation of GPER+ neurons abrogated itch responses, indicating that GPER+ neurons are antipruritic. Moreover, GPER-deficient mice and rats of either sex exhibited hypersensitivity to mechanical and chemical itch, a phenotype reversible by the µ type opioid receptor (MO...