A diverse family of GPCRs expressed in specific subsets of nociceptive sensory neurons

In vertebrates, peripheral chemosensory neurons express large families of G protein-coupled receptors (GPCRs), reflecting the diversity and specificit y of stimuli they detect. However, somatosensory neurons, which respond to chemical, thermal, or mechanical stimuli, are more broadly tuned. Here we d escribe a family of approximately 50 GPCRs related to Mas1, called mrgs, a subset of which is expressed in specific subpopulations of sensory neurons that detect painful stimuli. The expression patterns of mrgs thus reveal an unexpected degree of molecular diversity among nociceptive neurons. Some o f these receptors can be specifically activated in heterologous cells by RF amide neuropeptides such as NPFF and NPAF, which are analgesic in vivo. Thu s, mrgs may regulate nociceptor function and/or development, including the sensation or modulation of pain.