title: Copeptin, derived from isotocin precursor, is a probable prolactin releasing factor in carp.
abstract: Control of prolactin (PRL) release is of crucial importance for the multiple functions exerted by PRL in vertebrates. Recently identified hypothalamic PRL-releasing peptides displayed additional neuromodulatory activities and in fish only few could be detected close to lactotrophs. Here we describe the C-terminal peptide processed from the carp isotocin precursor as probable physiologically relevant regulator of PRL release in carp. The amino acid sequence derived from the complete isotocin precursor gene of Cyprinus carpio, predicted a C-terminal peptide uncleaved between the neurophysin (Np) and copeptin (Cp) domain. Accordingly, antibodies against synthetic Np- and Cp-specific oligopeptides both immunodetected a 13kDa protein (cNpCp) in total pituitary proteins and showed abundant immunoreaction in hypothalamic axons in direct contact with lactotrophs in the rostral pars distalis of carp pituitary gland sections. Finally, incubation of cultured carp pituitary explants with purified carp cNpCp resulted in a potent stimulation of PRL release.
authors.affiliation: Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
authors.forename: C M
authors.initials: CM
authors.lastname: Flores
authors.forename: D
authors.initials: D
authors.lastname: Muñoz
authors.forename: M
authors.initials: M
authors.lastname: Soto
authors.forename: G
authors.initials: G
authors.lastname: Kausel
authors.forename: A
authors.initials: A
authors.lastname: Romero
authors.forename: J
authors.initials: J
authors.lastname: Figueroa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002347:Carps / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000235:genetics; D006020:Glycopeptides / Q000097:blood / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000235:genetics / Q000502:physiology; D010902:Pituitary Gland / Q000502:physiology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D016415:Sequence Alignment; D013973:Thyrotropin-Releasing Hormone / Q000502:physiology*
chemical_list: D006020:Glycopeptides; C048197:copeptins; D010121:Oxytocin; C008215:isotocin; D013973:Thyrotropin-Releasing Hormone; D004247:DNA