Human sensory neuron specific receptor 4 (SNSR4 or MrgX1) is restricted to a subpopulation of sensory neurons in both humans and rat. These neurons are known to express other nociceptive markers such as IB4 and SNSR4 agonists such as BAM 8-22 are pro-nociceptive in rodents. SNSR4 activation might have a pro-nociceptive role in pain, and an antagonist may, therefore, have therapeutic value as an analgesic. 4a There is also a contradictory ...