Neuromedin U-23 (NMU-23) is a neuropeptide involved in diverse biological processes, including smooth muscle contraction, energy homeostasis, and nociception.1It is an agonist of neuromedin-U receptor 1 (NMUR1; EC50= 0.17 nM for the human receptor in a calcium mobilization assay using HEK293 cells) and NMUR2 (EC50= ~1.4-2 nM for arachidonic acid release in CHO cells expressing the human receptor).2,3NMU-23 (1 μM) induces contractions in isolated rat colon smooth muscle strips.4It decreases body weight and food intake and increases core body temperature in mice when administered at a dose of 36 μg/animal.5Intrathecal administration of NMU-23 decreases the mechanical pain threshold in the von Frey test in rats.6