title: Isolation, primary structure, and effects on alpha-melanocyte-stimulating hormone release of frog neurotensin.
abstract: Neurotensin (NT) was isolated in pure form from the small intestine of the European green frog, Rana ridibunda, and its primary structure was established as pGlu-Ala-His-Ile-Ser-Lys-Ala-Arg-Arg-Pro-Tyr-Ile-Leu. This sequence contains five amino acid substitutions (Leu2-->Ala, Tyr3-->His, Glu4-->Ile, Asn5-->Ser, and Pro7-->Ala) compared with human NT. A peptide with identical chromatographic properties was identified in an extract of frog brain. Synthetic frog NT produced a concentration-dependent increase in alphaMSH release from perifused frog pars intermedia cells, with an ED50 of 5 x 10(-9) M. A maximum response (276.3 +/- 45.5% above basal release) was produced by a 10(-8) M concentration. Repeated administration of NT to melanotrope cells revealed the occurrence of a rapid and pronounced desensitization mechanism. The data are consistent with a possible role for the peptide as a hypophysiotropic factor in amphibians.
authors.affiliation: European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U-413, University of Rouen, Mont-Saint-Aignan, France.
authors.forename: L
authors.initials: L
authors.lastname: Desrues
authors.forename: M C
authors.initials: MC
authors.lastname: Tonon
authors.forename: J
authors.initials: J
authors.lastname: Leprince
authors.forename: H
authors.initials: H
authors.lastname: Vaudry
authors.forename: J M
authors.initials: JM
authors.lastname: Conlon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D009496:Neurotensin / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D011895:Rana ridibunda; D000521:alpha-MSH / Q000378:metabolism*
chemical_list: D009496:Neurotensin; D000521:alpha-MSH