Urotensin I was found to be a close structural and biological homolog of the ovine hypothalamic corticotropin-releasing factor (CRF) and the frog skin peptide sauvagine. Urotensin I is a 41 aa peptide. which showed prolonged hypotensive effects in mammals. Urotensins are neuropeptide secreted from the urophysis in the caudal neurosecretory system of the fishes. | 