title: A novel amphibian hypothalamic neuropeptide: isolation, localization, and biological activity.
abstract: Neuropeptides similar to the molluscan cardioexcitatory Phe-Met-Arg-Phe-NH2 have been identified in several vertebrates and characterized by the RFa motif at their C terminus (RFa peptides). In this study, we sought to identify an amphibian hypothalamic RFa peptide that may regulate secretion of hormones by the anterior pituitary gland. An acid extract of bullfrog hypothalami was passed through C-18 reversed-phase cartridges, and then the retained material was subjected to HPLC, initially using a C-18 reversed-phase column. RFa immunoreactivity was measured in the eluted fractions by a dot immunoblot assay employing an antiserum raised against RFa. Immunoreactive fractions were subjected to further cation exchange and reversed-phase HPLC purification. The isolated peptide was a novel RFa peptide and shown to have the sequence Ser-Leu-Lys-Pro-Ala-Ala-Asn-Leu-Pro-Leu-Arg-Phe-NH2. The cell bodies and terminals containing this peptide were localized immunohistochemically in the suprachiasmatic nucleus and median eminence, respectively. This RFa peptide stimulated, in a dose-related way, the release of GH from cultured pituitary cells, its threshold concentration ranging between 10(-9) and 10(-8) M. This peptide did not have any appreciable effect on the secretion of PRL and gonadotropins. It was ascertained that the peptide was also effective in elevating the circulating GH level when administered systemically. Thus, the amphibian hypothalamus was revealed to contain a novel functional RFa peptide that stimulates GH release. This peptide was designated frog GH-releasing peptide.
authors.affiliation: Department of Biology, School of Education, Waseda University, Tokyo, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Koda
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ukena
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Teranishi
authors.forename: Shinji
authors.initials: S
authors.lastname: Ohta
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Sakae
authors.initials: S
authors.lastname: Kikuyama
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Tsutsui
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D001921:Brain / Q000033:anatomy & histology; D001923:Brain Chemistry / Q000502:physiology; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D019835:FMRFamide / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D007030:Hypothalamo-Hypophyseal System / Q000033:anatomy & histology / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D007986:Luteinizing Hormone / Q000378:metabolism; D009479:Neuropeptides / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D010903:Pituitary Gland, Anterior / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D011863:Radioimmunoassay; D011892:Rana catesbeiana
chemical_list: D007028:Hypothalamic Hormones; D009479:Neuropeptides; D019835:FMRFamide; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone