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-His-Trp-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.

Guinea Pig Gonadotropin-Releasing Hormone: Expression Pattern, Characterization and Biological Activity in Rodents

“…RIAs were performed as previously described [2, 27]and standards were radiolabeled following established protocols [27, 41]. The RIA systems were as follows:…”

“…To date, 15 GnRH molecular variants have been sequenced from vertebrate and protochordate nerve tissue [1, 2]. In addition to this molecular diversity, most vertebrate species express more than one GnRH form [1, 2, 3].…”

“…In addition to this molecular diversity, most vertebrate species express more than one GnRH form [1, 2, 3]. The multiplicity of GnRH isoforms has been demonstrated in all seven classes of vertebrates: jawless fish [4, 5, 6], cartilaginous fish [7], bony fishes [1, 2, 3, 8], amphibians [9, 10], reptiles [11], birds [12, 13]and mammals [14, 15]. However, some of the identified GnRHs do not appear to control the pituitary gonadotropins, and their function remains uncertain.…”

Induction of final oocyte maturation in Cyprinidae fish by hypothalamic factors: a review

“…Among vertebrates Teleostei are the group where the highest number of GnRH forms occur (Chen and Fernald, 2008). A total of eight GnRH forms have been identified until now (Matsuo et al, 1971;Sherwood et al, 1983;Yu et al, 1988;Bogerd et al, 1992;Powell et al, 1994;Carolsfeld et al, 2000;Montaner et al, 2001;Adams et al, 2002).…”

Structure and Biological Activity of Gonadotropin-Releasing Hormone Isoforms Isolated from Rat and Hamster Brains

“…To date, 13 GnRH forms have been characterized in vertebrates and named for the species in which they were initially isolated [2, 3]. All the variants are decapeptides, in which the amino-terminus (pGlu), carboxy-terminus (NH 2 ) and positions 1, 4, 9 and 10 are conserved.…”