Novel fish hypothalamic neuropeptide

Abstract

Recently, we identified novel avian and amphibian hypothalamic neuropeptides that inhibited gonadotropin release and stimulated growth hormone release. They were characterized by a similar structure including the C-terminal LPLRF-NH 2 motif. To clarify that the expression of these novel hypothalamic neuropeptides is a conserved property in vertebrates, we characterized a cDNA encoding a similar novel peptide, having LPLRF-NH 2 from the goldfish brain, by a combination of 3¢ and 5¢ rapid amplification of cDNA ends (RACE). The deduced peptide precursor consisted of 197 amino acid residues, encoding three putative peptide sequences that included -LPXRF (where X is L or Q) at their C-termini. Mass spectrometric analyses revealed that a tridecapeptide (SGTGLSATLPQRF-NH 2 ) was derived from the precursor in the brain as an endogenous ligand. Southern blotting analysis of reverse-transcriptase-mediated PCR products demonstrated a specific expression of the goldfish peptide gene in the diencephalon. In situ hybridization revealed the cellular localization of goldfish peptide mRNA in the nucleus posterioris periventricularis in the hypothalamus. Immunoreactive cell bodies were also restricted to the the nucleus posterioris periventricularis and the nervus terminalis and immunoreactive fibers were distributed in several brain regions including the nucleus lateralis tuberis pars posterioris and pituitary. Thus, the goldfish hypothalamus expresses a novel neuropeptide containing the C-terminal -LPQRF-NH 2 sequence, which may possess multiple regulatory functions and act, at least partly, on the pituitary to regulate pituitary hormone release.

Melatonin induces the expression of gonadotropin-inhibitory hormone in the avian brain

“…In situ hybridization of GnIH mRNA was conducted by using a digoxigenin-labeled antisense RNA probe as described (5,(26)(27)(28). After hybridization, the sections were incubated with alkaline phosphatase-labeled sheep anti-digoxigenin antibody (Anti-digoxigenin-AP, Fab fragments; Roche Diagnostics), and immunoreactive product was detected by immersing the sections in a substrate solution (nitroblue tetrazolium͞5-bromo-4-chloro-3-indolyl phosphate stock solution; Roche Diagnostics).…”

GnIH plays a negative role in regulating GtH expression in the common carp, Cyprinus carpio L.

“…Different peptides and species differences maybe also resulted to different results. In teleosts, the only mature peptide was the goldfish LPXRFa-3 (Sawada et al, 2002). However, in the drug treatment experiments, LPXRFa-1/2 were also chose.…”

“…We chose GnIH-III peptide as treatment drug, because it has been proven existing in goldfish (Sawada et al, 2002). It was dissolved in phosphate-buffered saline (PBS, PH = 7.2) for static incubation and injection experiments.…”

“…So far, GnIH cDNA sequences have been identified in goldfish, grass puffer, zebrafish and tilapia (Biran et al, 2014;Shahjahan et al, 2011;Sawada et al, 2002;Zhang et al, 2010). In most of these reports, GnIH peptides were named LPXRFa-1/2/3.…”

Seasonal Variation in the Expression of Five Subtypes of Gonadotropin-releasing Hormone Receptor Genes in the Brain of Masu Salmon from Immaturity to Spawning

“…One of these peptides may be an LPXRFamide, a member of a family of peptides that terminate in the sequence LPXRF-NH2 (where X=L or Q; see Tsutsui and Ukena, 2006, for review). In goldfish, a novel precursor gene encodes three different LPXRFamides, although only one peptide (gfLPXRFa-3) may be produced in the brain and TN (Sawada et al, 2002). The other RFamide may be Carassius RFamide (C-RFa, Fujimoto et al, 1998).…”