The 41-amino acid CRF fulfils all the criteria for a corticotrophin releasing factor, although considerable evidence suggests that other factors, particularly VP, also play a physiologically significant role in controlling ACTH release. Although human CRF has now been identified as a 41-residue peptide, most studies to date have used oCRF-41 in their exploration of the physiology and pathology of the hypothalamic--pituitary--adrenal axis. Low doses of oCRF-41 appear to be safe, and for specif...