Potent endogenous agonist peptide for the newly identified sensory neuron specific receptor (SNSR); isolated from bovine adrenal medulla. EC50 values are 13 and 16 nM for human SNSR3 and SNSR4 respectively. Also potent opioid agonist (IC50 = 1.3 nM in guinea pig ileum preparation). Produces opioid- and non-opioid receptor mediated antinociceptive effects in vivo.