Primary Structure and Function of Three Gonadotropin-Releasing Hormones, Including a Novel Form, from an Ancient Teleost, Herring¹

Abstract

The evolution of GnRH and the role of multiple forms within the brain are examined. Three forms of GnRH were purified from the brain of Pacific herring (Clupea harengus pallasi) and characterized using Edman degradation and mass spectrometry. Two forms correspond with the known structures of chicken GnRH-II and salmon GnRH that are found in many vertebrate species. The third form, designated herring GnRH (hrGnRH), has a primary structure of pGlu-His-Trp-Ser-His-Gly-Leu-Ser-Pro-Gly-NH 2 . This novel peptide is a potent stimulator of gonadotropin II and GH release from dispersed fish pituitary cells. The content of hrGnRH in the pituitary was 8-fold that of salmon GnRH and 43-fold that of chicken GnRH-II, which provides supporting evidence that hrGnRH is involved in the release of gonadotropin.