Primary Structure of a Novel Gonadotropin-Releasing Hormone in the Brain of a Teleost, Pejerrey

Abstract

The neuropeptide GnRH is the major regulator of reproduction in vertebrates acting as a first signal from the hypothalamus to pituitary gonadotropes. Three GnRH molecular variants were detected in the brain of a fish, pejerrey (Odontesthes bonariensis), using chromatographic and immunological methods. The present study shows that one form is identical to chicken GnRH-II (sequence analysis and mass spectrometry) and the second one is immunologically and chromatographically similar to salmon GnRH. The third form was proven to be a novel form of GnRH by isolating the peptide from the brain and determining its primary structure by chemical sequencing and mass spectrometry. The sequence of the novel pejerrey GnRH is pGlu-HisTrp-Ser-Phe-Gly-Leu-Ser-Pro-Gly-NH 2 , which is different from the known forms of the vertebrate and protochordate GnRH family. The new form of GnRH is biologically active in releasing gonadotropin and GH from pituitary cells in an in vitro assay. (Endocrinology 142:

Relative potency of the forms of GnRH and their analogs on LH release in sea bass

“…In all major vertebrate groups cGnRH‐II coexists with one or more GnRH forms hypothesizing that the vertebrate GnRH neuronal system evolved from an ancestral cGnRH‐II like neuronal system involved in the control of reproduction (Lin et al ., 1998). Eight GnRH forms (sGnRH, mGnRH, cfGnRH, sbGnRH, cGnRH‐II, hrGnRH, mdGnRH and pGnRH) have been identified in the brain of different teleosts (Montaner et al ., 2001). At least two forms of GnRH coexist in the brain of most bony fishes: the ubiquitous cGnRH‐II and the species‐specific form (Sherwood et al ., 1994; King & Millar, 1995, 1997).…”

Three Forms of Gonadotropin-Releasing Hormone, Including a Novel Form, in a Basal Salmonid, Coregonus clupeaformis1

“…Each of sGnRH, cGnRH-II, hrGnRH, and pjGnRH is able to act in vitro in goldfish pituitary cells to release GtH and GH [3,5,32,33]. The wfGnRH had a greater effect on GtH/TSH-␣ subunit and a similar effect on GH compared with cGnRH-II.…”

“…It is now established that at least 3 GnRH forms are expressed in many teleost fish. However, some fish that evolved after herring (pejerrey, seabream, pacu, tilapia) have 3 forms of GnRH [5,[9][10][11]. The next order of fish to evolve is thought to be salmonids and, at about the same time, several orders of fresh-water fish, including catfish and goldfish/carps; in each of these groups of fish, only 2 forms of GnRH have been identified [8].…”

In silico and in situ characterization of the zebrafish (Danio rerio) gnrh3 (sGnRH) gene

“…This receptor mediated signal transduction pathway stimulates gonadal maturation, gametogenesis and production of sex steroids, which impose feedback on the HPG axis [7-12]. The evolutionary conserved GnRH decapeptide has been characterized directly or indirectly in a number of vertebrates and a few invertebrates and currently includes 15 different decapeptide variants [13,14], though if the common octopus ( Octopus vulgaris ) GnRH-like mature peptide (dodecapeptide) is included, a total of 16 variants have been characterized till day [15] (Fig. 1).…”

“… GnRH decapeptide conservation Sequence comparison of mature GnRH peptides [13-15], show complete similarity between Atlantic salmon GnRH-III and zebrafish Gnrh3. The common name, species of origin nomenclature, scientific name, GnRH-I, -II or -III nomenclature and corresponding mature GnRH peptides are shown.…”