Urocortin (UCN) is a 40 amino acid-long neuropeptide that is an endogenous ligand for corticotropin-releasing hormone (CRH) receptors. In fact, because UCN has an affinity for the CRH-R2{\beta} receptor that is ten fold higher than that of CRH, some researchers have suggested that UCN is the primary ligand for the CRH family of receptors.

Expression of UCN in the brain has been reported in a variety of regions, with some conflicting results. However, the majority of researchers would agree that UCN mRNA expression is most prominant in the Edinger-Westphal nucleus (EW) and the lateral superior olive. Other areas of reported expression include the cerebellum, hippocampus, neocortex, olfactory system, basal ganglia, amygdala, and the various regions of the hypothalamus.