Expression of mRNAs Encoding Hypothalamic Small Proteins, Neurosecretory Protein GL and Neurosecretory Protein GM, in the Japanese Quail, Coturnix japonica.

Neurosecretory protein GL (NPGL) and neurosecretory protein GM (NPGM) are novel neuropeptides that have been discovered in the hypothalamic infundibulum of chickens. NPGL and NPGM play important roles in lipid metabolism in juvenile chickens. The physiological functions of NPGL and NPGM in sexually mature birds remain unknown. The Japanese quail (Coturnix japonica) seems to be an appropriate model for analyzing NPGL and NPGM during sexual maturity. However, studies on NPGL or NPGM have yet to be reported in the Japanese quail. In the present study, we identified cDNAs encoding precursor proteins of NPGL and NPGM in the quail hypothalamus. In situ hybridization revealed that NPGL mRNA-expressing cells in the hypothalamus were localized in the infundibular nucleus and median eminence, and NPGM mRNA-expressing cells were only found in the mammillary nucleus. Immunohistochemistry revealed that NPGM-like immunoreactive cells were distributed in the mammillary nucleus, whereas NPGL-like immunoreactive cells were not detected in the hypothalamus. Real-time PCR analysis indicated that the expression of NPGL mRNA was higher in the hypothalamus of females than in that of males, and NPGM mRNA expression showed no sex differences. NPGL and NPGM mRNA expression in males was upregulated after 24 h of food deprivation. In females, only NPGM mRNA expression was increased by fasting. These results suggest that the physiological functions of NPGL and NPGM are different in quail, and these factors are involved in sex differences in energy metabolism.

Neurosecretory Protein GL Promotes Normotopic Fat Accumulation in Male ICR Mice.

Neurosecretory protein GL (NPGL) is a small secretory protein identified in the hypothalamus of birds and mammals. We recently reported that NPGL exerts obesogenic effects in obesity-prone C57BL6/J mice. However, whether NPGL elicits adiposity in different mouse strains is poorly understood. In this study, we generated transgenic mice overexpressing Npgl using the ICR strain (Npgl Tg mice) to elucidate the obesogenic effects of NPGL in different strains. Npgl Tg mice showed increased white adipose tissue (WAT) mass. Although the mass of brown adipose tissue (BAT) was slightly altered in Npgl Tg mice, hypertrophy of lipid droplets was also observed in BAT. In contrast, fat accumulation was not induced in the liver, with the upregulation of mRNAs related to hepatic lipolysis. These results support the hypothesis that NPGL causes obesity in several strains and species. This report highlights the pivotal role of NPGL in fat accumulation in adipose tissues and contributes to the elucidation of the biological mechanisms underlying obesity and metabolic diseases in heterogeneous populations.

Neurosecretory Protein GL Accelerates Liver Steatosis in Mice Fed Medium-Fat/Medium-Fructose Diet.

Sugar consumption can readily lead to obesity and metabolic diseases such as liver steatosis. We previously demonstrated that a novel hypothalamic neuropeptide, neurosecretory protein GL (NPGL), promotes fat accumulation due to the ingestion of sugar by rats. However, differences in lipogenic efficiency of sugar types by NPGL remain unclear. The present study aimed to elucidate the obesogenic effects of NPGL on mice fed different sugars (i.e., sucrose or fructose). We overexpressed the NPGL-precursor gene (Npgl) in the hypothalamus of mice fed a medium-fat/medium-sucrose diet (MFSD) or a medium-fat/medium-fructose diet (MFFD). Food intake and body mass were measured for 28 days. Body composition and mRNA expression of lipid metabolic factors were measured at the endpoint. Npgl overexpression potently increased body mass with fat accumulation in the white adipose tissue of mice fed MFFD, although it did not markedly affect food intake. In contrast, we observed profound fat deposition in the livers of mice fed MFFD but not MFSD. In the liver, the mRNA expression of glucose and lipid metabolic factors was affected in mice fed MFFD. Hence, NPGL induced liver steatosis in mice fed a fructose-rich diet.

Hypothalamic Overexpression of Neurosecretory Protein GL Leads to Obesity in Male C57BL/6J Mice.

INTRODUCTION: The mechanisms underlying obesity are not fully understood, necessitating the creation of novel animal models for the investigation of metabolic disorders. We have previously found that neurosecretory protein GL (NPGL), a newly identified hypothalamic neuropeptide, is involved in feeding behavior and fat accumulation in rats. However, the impact of NPGL on obesity remains unclear in any animal model. The present investigation sought to elucidate whether NPGL causes obesity in the obesity-prone mouse strain C57BL/6J. METHODS: We overexpressed the NPGL-precursor gene (Npgl) in the hypothalamus using adeno-associated virus in male C57BL/6J mice fed normal chow (NC) or a high-calorie diet (HCD). After 9 weeks of Npgl overexpression, we measured adipose tissues, muscle, and several organ masses in addition to food intake and body mass. To assess the effects of Npgl overexpression on peripheral tissues, we analyzed mRNA expression of lipid metabolism-related genes by quantitative RT-PCR. Whole body energy consumption was assessed using an O2/CO2 metabolism measurement before an apparent increase in body mass. RESULTS: Npgl overexpression increased food intake, body mass, adipose tissues and liver masses, and food efficiency under both NC and HCD, resulting in obesity observable within 8 weeks. Furthermore, we observed fat accumulation in adipose tissues and liver. Additionally, mRNA expression of lipid metabolism-related factors was increased in white adipose tissue and the liver after Npgl overexpression. Npgl overexpression inhibited energy expenditure during a dark period. CONCLUSION: Taken together, the present study suggests that NPGL can act as an obesogenic factor that acts within a short period of time in mice. As a result, this Npgl overexpression-induced obesity can be widely applied to study the etiology of obesity from genes to behavior.

Effects of Irregular Feeding on the Daily Fluctuations in mRNA Expression of the Neurosecretory Protein GL and Neurosecretory Protein GM Genes in the Mouse Hypothalamus.

Circadian desynchrony induced by a long period of irregular feeding leads to metabolic diseases, such as obesity and diabetes mellitus. The recently identified neurosecretory protein GL (NPGL) and neurosecretory protein GM (NPGM) are hypothalamic small proteins that stimulate food intake and fat accumulation in several animals. To clarify the mechanisms that evoke feeding behavior and induce energy metabolism at the appropriate times in accordance with a circadian rhythm, diurnal fluctuations in Npgl and Npgm mRNA expression were investigated in mice. Quantitative RT-PCR analysis revealed that the mRNAs of these two genes were highly expressed in the mediobasal hypothalamus during the active dark phase under ad libitum feeding. In mice restricted to 3 h of feeding during the inactive light phase, the Npgl mRNA level was augmented in the moment prior to the feeding period and the midnight peak of Npgm mRNA was attenuated. Moreover, the mRNA expression levels of clock genes, feeding regulatory neuropeptides, and lipid metabolic enzymes in the central and peripheral tissues were comparable to those of central Npgl and Npgm. These data suggest that Npgl and Npgm transcription fluctuates daily and likely mediates feeding behavior and/or energy metabolism at an appropriate time according to the meal timing.

Localization and function of neurosecretory protein GM, a novel small secretory protein, in the chicken hypothalamus.

Recently, we discovered a novel cDNA encoding the precursor of a small secretory protein, neurosecretory protein GL (NPGL), in the hypothalamic infundibulum of chickens. NPGL plays an important role in the regulation of growth and feeding. A database search indicated that the NPGL gene has a paralogous gene: neurosecretory protein GM (NPGM), also in chickens. We identified cDNA encoding the NPGM precursor in chickens. Morphological analysis showed that NPGM-containing cells are specifically localized in the medial mammillary nucleus (MM) and infundibular nucleus (IN) in the hypothalamus. In addition, we found that NPGM and NPGL are co-localized, especially in the MM. The expression levels of NPGM mRNA gradually decreased during post-hatch development, in contrast to those of NPGL mRNA. Moreover, we investigated the relationship between NPGM and other known factors. NPGM was found to be produced in histaminergic neurons in the MM. NPGM and histidine decarboxylase, a histamine-producing enzyme, displayed similar expression patterns during post-hatch development. Acute intracerebroventricular injection of NPGM decreased food intake, similar to the effect of histamine. To our knowledge, this is the first report of the localization and function of NPGM in the brain of vertebrates. These results will further advance the understanding mechanisms underlying energy homeostasis.

Avian and murine neurosecretory protein GL participates in the regulation of feeding and energy metabolism.

Probing previously unknown neuropeptides and/or peptide hormones is essential for our understanding of the regulation of energy homeostasis in the brain. We recently performed a cDNA subtractive screening of the chicken hypothalamus, which contained one of the feeding and energy metabolic centers. We found a gene encoding a novel protein of 182 amino acid residues, including one putative small secretory protein of 80 amino acid residues. The C-terminal amino acids of the small protein were Gly-Leu-NH2, and as a result, the small protein was termed neurosecretory protein GL (NPGL). Subcutaneous and intracerebroventricular infusions of NPGL increased body mass gain in chicks, suggesting a central role for this protein in regulating growth and energy homeostasis. A database search revealed that the Npgl gene is conserved in vertebrates, including mice and rats. This review summarizes the advances in the characterization, localization, and biological action of NPGL, in birds and rodents.

Effects of chronic intracerebroventricular infusion of neurosecretory protein GL on body mass and food and water intake in chicks.

Recently, we discovered a novel cDNA encoding the precursor of a small secretory protein, neurosecretory protein GL (NPGL), in the chicken mediobasal hypothalamus. In this study, immunohistochemical analysis revealed that NPGL was produced in the infundibular and medial mammillary nuclei of the mediobasal hypothalamus, with immunoreactive fibers also detected in the hypothalamus and the median eminence. As it is known that these regions are involved in feeding behavior in chicks, we surveyed the effects of chronic intracerebroventricular infusion of NPGL on feeding behavior and body mass for a period of two weeks. NPGL stimulated food and water intake, with a concomitant increase in body mass. However, NPGL did not influence mRNA expression of several hypothalamic ingestion-related neuropeptides. Our data suggest that NPGL may be a novel neuronal regulator involved in growth processes in chicks.

Neurosecretory protein GL stimulates food intake, de novo lipogenesis, and onset of obesity.

Mechanisms underlying the central regulation of food intake and fat accumulation are not fully understood. We found that neurosecretory protein GL (NPGL), a newly-identified neuropeptide, increased food intake and white adipose tissue (WAT) in rats. NPGL-precursor gene overexpression in the hypothalamus caused increases in food intake, WAT, body mass, and circulating insulin when fed a high calorie diet. Intracerebroventricular administration of NPGL induced de novo lipogenesis in WAT, increased insulin, and it selectively induced carbohydrate intake. Neutralizing antibody administration decreased the size of lipid droplets in WAT. Npgl mRNA expression was upregulated by fasting and low insulin levels. Additionally, NPGL-producing cells were responsive to insulin. These results point to NPGL as a novel neuronal regulator that drives food intake and fat deposition through de novo lipogenesis and acts to maintain steady-state fat level in concert with insulin. Dysregulation of NPGL may be a root cause of obesity.

Neurosecretory Protein GL, a Hypothalamic Small Secretory Protein, Participates in Energy Homeostasis in Male Mice.

We have recently identified from the avian hypothalamus a complementary DNA encoding a small secretory protein termed neurosecretory protein GL (NPGL). In chicks, NPGL increases body weight gain without affecting food intake. A database search reveals that NPGL is conserved throughout vertebrates. However, the central distribution and functional role of NPGL remains to be elucidated in mammals. In this study, we identified the precursor complementary DNA encoding NPGL from the mouse hypothalamus. Quantitative reverse transcription polymerase chain reaction and morphological analyses revealed that NPGL precursor messenger RNA is robustly expressed in the mediobasal hypothalamus with NPGL neurons specifically localized to the lateroposterior part of the arcuate nucleus in the hypothalamus. NPGL-immunoreactive fibers were observed in close anatomical contact with pro-opiomelanocortin neurons in the rostral region of the arcuate nucleus. NPGL messenger RNA expression was elevated by 24-hour fasting and reduced by feeding of a high-fat diet for 5 weeks. Furthermore, intracerebroventricular injection of mature NPGL increased food intake, pointing to an important role in feeding. Taken together, these findings report on the distribution of NPGL in the mammalian brain and point to an important role for this neuropeptide in energy homeostasis.

Identification and localization of gonadotropin-inhibitory hormone (GnIH) orthologs in the hypothalamus of the red-eared slider turtle, Trachemys scripta elegans.

Gonadotropin-inhibitory hormone (GnIH) was discovered in 2000 as a novel hypothalamic neuropeptide that inhibited gonadotropin release in the Japanese quail. GnIH and its orthologs have a common C-terminal LPXRFamide (X=L or Q) motif, and have been identified in vertebrates from agnathans to humans, apart from reptiles. In the present study, we characterized a cDNA encoding GnIH orthologs in the brain of the red-eared slider turtle. The deduced precursor protein consisted of 205 amino-acid residues, encoding three putative peptide sequences that included the LPXRFamide motif at their C-termini. In addition, the precursor sequence was most similar to those of avian species. Immunoaffinity purification combined with mass spectrometry confirmed that three mature peptides were produced in the brain. In situ hybridization and immunohistochemistry showed that turtle GnIH-containing cells were restricted to the periventricular hypothalamic nucleus. Immunoreactive fibers were densely distributed in the median eminence. Thus, GnIH and related peptides may act on the pituitary to regulate pituitary hormone release in turtles as well as other vertebrates.

Identification of a cDNA encoding a novel small secretory protein, neurosecretory protein GL, in the chicken hypothalamic infundibulum.

To find novel neuropeptide and/or peptide hormone precursors in the avian brain, we performed a cDNA subtractive screen of the chicken hypothalamic infundibulum, which contains one of the feeding and neuroendocrine centers. After sequencing 596 clones, we identified a novel cDNA encoding a previously unknown protein. The deduced precursor protein consisted of 182 amino acid residues, including one putative small secretory protein of 80 amino acid residues. This small protein was flanked at the N-terminus by a signal peptide and at the C-terminus by a glycine amidation signal and a dibasic amino acid cleavage site. Because the predicted C-terminal amino acids of the small protein were Gly-Leu-NH2, the small protein was named neurosecretory protein GL (NPGL). Quantitative RT-PCR analysis demonstrated specific expression of the NPGL precursor mRNA in the hypothalamic infundibulum. Furthermore, the mRNA levels in the hypothalamic infundibulum increased during post-hatching development. In situ hybridization analysis showed that the cells containing the NPGL precursor mRNA were localized in the medial mammillary nucleus and infundibular nucleus within the hypothalamic infundibulum of 8- and 15-day-old chicks. Subcutaneous infusion of NPGL in chicks increased body weight gain without affecting food intake. To our knowledge, this is the first report to describe the identification and localization of the NPGL precursor mRNA and the function of its translated product in animals. Our findings indicate that NPGL may participate in the growth process in chicks.

Molecular evolution of GPCRs: 26Rfa/GPR103.

Neuropeptides possessing the Arg-Phe-NH2 (RFamide) motif at their C-termini (designated as RFamide peptides) have been characterized in a variety of animals. Among these, neuropeptide 26RFa (also termed QRFP) is the latest member of the RFamide peptide family to be discovered in the hypothalamus of vertebrates. The neuropeptide 26RFa/QRFP is a 26-amino acid residue peptide that was originally identified in the frog brain. It has been shown to exert orexigenic activity in mammals and to be a ligand for the previously identified orphan G protein-coupled receptor, GPR103 (QRFPR). The cDNAs encoding 26RFa/QRFP and QRFPR have now been characterized in representative species of mammals, birds, and fish. Functional studies have shown that, in mammals, the 26RFa/QRFP-QRFPR system may regulate various functions, including food intake, energy homeostasis, bone formation, pituitary hormone secretion, steroidogenesis, nociceptive transmission, and blood pressure. Several biological actions have also been reported in birds and fish. This review summarizes the current state of identification, localization, and understanding of the functions of 26RFaQRFP and its cognate receptor, QRFPR, in vertebrates.

Identification, localization and function of a novel neuropeptide, 26RFa, and its cognate receptor, GPR103, in the avian hypothalamus.

Several neuropeptides possessing the RFamide motif at their C-termini (designated RFamide peptides) have been characterized in the hypothalamus of a variety of vertebrates. Since the discovery of the 26-amino acid RFamide peptide (termed 26RFa) from the frog brain, 26RFa has been shown to exert orexigenic activity in mammals and to be a ligand of the previously identified orphan G protein-coupled receptor GPR103. Recently, we have identified 26RFa in the avian brain by molecular cloning of the cDNA encoding the 26RFa precursor and mass spectrometry analysis of the mature peptide. 26RFa-producing neurons are exclusively located in the hypothalamus whereas GPR103 is widely distributed in the avian brain. Furthermore, avian 26RFa stimulates feeding behavior in broiler chicks. This review summarizes the advances in the identification, localization, and functions of 26RFa and its cognate receptor GPR103 in vertebrates and highlights recent progress made in birds.

Identification, localization, and function of a novel avian hypothalamic neuropeptide, 26RFa, and its cognate receptor, G protein-coupled receptor-103.

Several neuropeptides with the C-terminal RFamide sequence have been identified in the hypothalamus of a variety of vertebrates. Among the RFamide peptide groups, however, only LPXRFamide peptides, including gonadotropin-inhibitory hormone, have been characterized in the avian brain. In the present study, we sought for the presence of other RFamide peptides in the avian hypothalamus. We identified a cDNA encoding an RFamide peptide orthologous to 26RFa (also referred to as QRFP) in the hypothalamus of the Japanese quail. The deduced quail 26RFa precursor consisted of 120-amino-acid residues, encoding one RFamide peptide with 27 amino acids. This RFamide peptide was flanked at the N terminus by a dibasic amino acid cleavage site and at the C terminus by a glycine amidation signal. Quantitative RT-PCR analysis demonstrated specific expression of quail 26RFa mRNA in the diencephalon including the hypothalamus. Furthermore, mass spectrometry analysis revealed the presence of a peptide exhibiting the mass of mature 26RFa, indicating that the peptide is actually produced from the precursor in the diencephalon. 26RFa-producing cell bodies were localized in the anterior hypothalamic nucleus in the brain. Synthetic 26RFa increased intracellular Ca(2+) concentration in HEK293T cells transfected with the chicken G protein-coupled receptor GPR103. Intracerebroventricular injection of 26RFa in broiler chicks stimulated feeding behavior. These data provide the first evidence for the occurrence of the peptide 26RFa in the avian hypothalamus and indicate that this peptide exerts orexigenic activity.

Structures and diverse functions of frog growth hormone-releasing peptide (fGRP) and its related peptides (fGRP-RPs): a review.

A new Arg-Phe-NH(2) (RFamide) peptide has been discovered in the amphibian hypothalamus. The cell bodies and terminals containing this peptide were localized in the suprachiasmatic nucleus and median eminence, respectively. This peptide was further revealed to have a considerable growth hormone (GH)-releasing activity in vitro and in vivo and hence designated as frog GH-releasing peptide (fGRP). Molecular cloning of cDNA encoding the fGRP precursor polypeptide revealed that it encodes fGRP and its putative gene-related peptides (fGRP-RP-1, -RP-2, and -RP-3). Subsequently, we identified these putative fGRP-RPs as mature peptides and analyzed their hypophysiotropic activities. Only fGRP-RP-2 stimulated the release of GH and prolactin (PRL) in vitro and in vivo. Thus, in addition to fGRP, fGRP-RP-2 acts as a hypothalamic factor on the frog pituitary to stimulate the release of GH and PRL.

Novel fish hypothalamic neuropeptides stimulate the release of gonadotrophins and growth hormone from the pituitary of sockeye salmon.

We recently identified a cDNA encoding three novel fish hypothalamic neuropeptides, having LPXRF-NH(2) from the goldfish brain. In this study, to clarify the physiological functions of these three LPXRFamide peptides (gfLPXRFa-1, -2, and -3), we analysed the localisation and hypophysiotrophic activity of these peptides using sockeye salmon, Oncorhynchus nerka, in which immunoassay systems for several anterior pituitary hormones have been developed. gfLPXRFa-immunoreactive cell bodies were detected in the nucleus posterioris periventricularis of the hypothalamus and immunoreactive fibres were distributed in various brain regions and the pituitary. We also detected gfLPXRFa-immunoreactivity in the pituitary by competitive enzyme-linked immunosorbent assay combined with reversed-phase HPLC. These three gfLPXRFamide peptides stimulated the release of FSH, LH and GH, but did not affect the release of prolactin (PRL) and somatolactin (SL) from cultured pituitary cells. These results suggest that novel fish hypothalamic LPXR-Famide peptides exist in the brain and pituitary of sockeye salmon and stimulate the release of gonadotrophins and GH from the pituitary.

Gonadotropin-inhibitory hormone inhibits gonadal development and maintenance by decreasing gonadotropin synthesis and release in male quail.

Until recently, any neuropeptide that directly inhibits gonadotropin secretion had not been identified. We recently identified a novel hypothalamic dodecapeptide that directly inhibits gonadotropin release in quail and termed it gonadotropin-inhibitory hormone (GnIH). The action of GnIH on the inhibition of gonadotropin release is mediated by a novel G protein-coupled receptor in the quail pituitary. This new gonadotropin inhibitory system is considered to be a widespread property of birds and provides us with an unprecedented opportunity to study the regulation of avian reproduction from an entirely novel standpoint. To understand the physiological role(s) of GnIH in avian reproduction, we investigated GnIH actions on gonadal development and maintenance in male quail. Continuous administration of GnIH to mature birds via osmotic pumps for 2 wk decreased the expressions of gonadotropin common alpha and LHbeta subunit mRNAs in a dose-dependent manner. Plasma LH and testosterone concentrations were also decreased dose dependently. Furthermore, administration of GnIH to mature birds induced testicular apoptosis and decreased spermatogenic activity in the testis. In immature birds, daily administration of GnIH for 2 wk suppressed normal testicular growth and rise in plasma testosterone concentrations. An inhibition of juvenile molt also occurred after GnIH administration. These results indicate that GnIH inhibits gonadal development and maintenance through the decrease in gonadotropin synthesis and release. GnIH may explain the phenomenon of photoperiod-induced gonadal regression before an observable decline in hypothalamic GnRH in quail. To our knowledge, GnIH is the first identified hypothalamic neuropeptide inhibiting reproductive function in any vertebrate class.

A new member of the hypothalamic RF-amide peptide family, LPXRF-amide peptides: structure, localization, and function.

Recently, we identified a novel hypothalamic neuropeptide with a C-terminal LPLRF-amide sequence in the quail brain. This avian neuropeptide was shown to inhibit gonadotropin release from the cultured anterior pituitary. This peptide is the first hypothalamic peptide that inhibited gonadotropin release reported in vertebrates. We, therefore, termed it gonadotropin-inhibitory hormone (GnIH). After this finding, we found that GnIH-related peptides were present in the brains of other vertebrates, such as mammals, amphibians, and fish. These GnIH-related peptides possessed a LPXRF-amide (X=L or Q) motif at their C-termini in all investigated animals. Mass spectrometric analyses combined with immunoaffinity chromatography were powerful techniques for the identification of mature endogenous LPXRF-amide peptides. The identified LPXRF-amide peptides were found to be localized in the hypothalamus and brainstem areas, and to regulate pituitary hormone release. Subsequently, cDNAs that encode LPXRF-amide peptides were characterized in vertebrate brains. In this review, we summarize the identification, localization, and function of a new member of the hypothalamic RF-amide peptide family, LPXRF-amide peptides in vertebrates. Recent studies on the receptors for LPXRF-amide peptides will also be reviewed.

Novel fish hypothalamic neuropeptide.

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-NH2 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-NH2 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-NH2) 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-NH2 sequence, which may possess multiple regulatory functions and act, at least partly, on the pituitary to regulate pituitary hormone release.