Partial purification and characterization of a novel growth hormone-releasing factor (GRF) from teleost brain related to the rat hypothalamic peptide

A growth hormone-releasing factor (GRF)-like molecule has been partially purified and characterized from acid extracts of codfish (Gadhus morhua) brain using immunoaffinity and gel chromatography, followed by HPLC. This material has a mol.wt. which is similar to known mammalian forms of GRF but is immunologically and/or chromatographically distinct from previously described GRF peptides. However, it is related to rat(r) GRF(1-43) since it causes marked displacement in the rGRF RIA. Codfish GRF is a highly specific and potent hypophysiotropic factor as shown by its ability to stimulate the release of GH, but no other hormone, from rat anterior pituitary cells in vitro. These findings suggest that, phylogenetically, GRF is an ancient molecule with its biologic activity and certain immunoreactive domain(s) conserved, at least, from teleost to mammal.