Urocortin III is a neuropeptide hormone and member of the corticotropin-releasing factor (CRF) family which includes mammalian CRF , urocortin , urocortin II , frog sauvagine, and piscine urotensin I.1 Human urocortin III shares 90, 40, 37, and 21% identity to mouse urocortin III , mouse urocortin II , human urocortin , and mouse urocortin, respectively. Urocortin III selectively binds to type 2 CRF receptors (Kis = 21.7, 13.5, and >100 nM for rat CRF2α, rat CRF2β, and human CRF1, respectively). It stimulates cAMP production in CHO cells expressing rat CRF2α and mouse CRF2β (EC50s = 0.16 and 0.12 nM, respectively) as well as cultured anterior pituitary cells expressing endogenous CRF2β. Urocortin III is co-released with insulin to potentiate glucose-stimulated somatostatin release in vitro in human pancreatic β-cells.2 In vivo, urocortin III reduces food intake in a dose- and time-dependent manner in mice with a minimum effective dose (MED) of 0.3 nmol/animal.3 It increases swimming time in a forced swim test in mice, indicating antidepressant-like activity.4

References
1. Lewis, K., Li, C., Perrin, M.H., et al. Identification of urocortin III, an additional member of the corticotropin-releasing factor (CRF) family with high affinity for the CRF2 receptor. Proc. Natl. Acad. Sci. U.S.A. 98(13), 7570-7575 (2001).
2. van der Meulen, T., Donaldson, C.J., CÁceres, E., et al. Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion. Nat. Med. 21(7), 769-776 (2015).
3. Pelleymounter, M.A., Joppa, M., Ling, N., et al. Behavioral and neuroendocrine effects of the selective CRF2 receptor agonists urocortin II and urocortin III. Peptides 25(4), 659-666 (2004).
4. Tanaka, M., KÁdÁr, K., TÓth, G., et al. Antidepressant-like effects of urocortin 3 fragments. Brain Res. Bull. 84(6), 414-418 (2011).