Interrelation between melanocyte-stimulating hormone and melanin-concentrating hormone in physiological body color change: roles emerging from barfin flounder Verasper moseri.

In teleosts, as their names suggest, the main target cells of melanocyte-stimulating hormone (MSH) and melanin-concentrating hormone (MCH) are the chromatophores in the skin, where these peptide hormones play opposing roles in regulating pigment migration. These effects are obvious especially when their activities are examined in vitro. On the contrary, while MCH also exhibits activity in vivo, MSH does not always stimulate pigment dispersion in vivo because of predominant sympathetic nervous system.

Food deprivation increases the expression of the prepro-orexin gene in the hypothalamus of the barfin flounder, Verasper moseri.

Orexins (orexin-A and -B) are involved in the regulation of food intake in mammals. In the barfin flounder, Verasper moseri, we previously reported that orexin-A-like-immunoreactive (ir) cell bodies are localized in the hypothalamus, which is a possible orexigenic center in fish. However, the physiological roles of orexin in the barfin flounder remain unclear.

Melanocortin receptor subtypes in interrenal cells and corticotropic activity of α-melanocyte-stimulating hormones in barfin flounder, Verasper moseri.

The aim of this study was to characterize the pituitary-interrenal axis in barfin flounder, a flatfish. Adrenocorticotropic hormone (ACTH) and melanocortin 2 receptor (MC2R) have been shown to be indispensable substances in pituitary and interrenal cells for cortisol release, respectively. We previously identified ACTH in the pars distalis of the barfin flounder pituitary gland, and detected transcripts of Mc1r, Mc4r, and Mc5r in the head kidney wherein interrenal cells are located.

Differential expressions of melanocortin receptor subtypes in melanophores and xanthophores of barfin flounder.

alpha-Melanocyte-stimulating hormone (alpha-MSH) is a member of the melanocortin (MC) family, and the MC receptor (MCR) is a member of the G protein-coupled receptor (GPCR) superfamily. We previously found that in barfin flounder, a flatfish, alpha-MSH with an acetyl group at the N-terminus stimulated pigment dispersion in xanthophores; however, this effect was not observed in melanophores. Therefore, the present study was undertaken to find which MCR subtypes are expressed in these pigment cells in order to elucidate how acetylation regulates activities of alpha-MSH-related peptides.

Structural and functional diversity of proopiomelanocortin in fish with special reference to barfin flounder.

Proopiomelanocortin (POMC) is a precursor of adrenocorticotropic hormone (ACTH), melanocyte-stimulating hormone (MSH), and endorphin (END). We have characterized POMC systems in barfin flounder. The results revealed unique aspects of POMC systems.

Possible paracrine function of alpha-melanocyte-stimulating hormone and inhibition of its melanin-dispersing activity by N-terminal acetylation in the skin of the barfin flounder, Verasper moseri.

Melanocyte-stimulating hormone (MSH) is generated from a precursor protein, proopiomelanocortin (POMC), mainly in the pituitary. The barfin flounder, Verasper moseri, expresses three different POMC genes (Pomc), among which Pomc-c is also expressed in the skin. Herein, we characterized the biological significance of POMC and MSH produced in barfin flounder skin.

Green light stimulates somatic growth in the barfin flounder Verasper moseri.

We examined the effects of different light wavelengths-blue, green, and red-on the somatic growth of the barfin flounder Verasper moseri, a flatfish. The light sources used were fluorescent lamps and a combination of daylight and fluorescent lamps that produced ambient light. These light sources were filtered using blue, green, or red filters.

Transcription elements and functional expression of proopiomelanocortin genes in the pituitary gland of the barfin flounder.

Proopiomelanocortin (POMC) is the precursor of adrenocorticotropin, melanocyte-stimulating hormone, and endorphin. Barfin flounder Verasper moseri possesses three POMC mRNAs. In this study, we determined the amino acid sequences of POMC-A, POMC-B, and POMC-C in this fish and investigated the effects of black or white background on the expression of these genes.

Changes in brain seabream GnRH mRNA and pituitary seabream GnRH peptide levels during ovarian maturation in female barfin flounder.

The pleuronectid barfin flounder Verasper moseri expresses three forms of gonadotropin-releasing hormones (GnRHs), i.e., seabream GnRH (sbGnRH), salmon GnRH, and chicken GnRH-II.

Food deprivation increases the expression of melanocortin-4 receptor in the liver of barfin flounder, Verasper moseri.

The melanocortin (MC) system is composed of melanocyte-stimulating hormone, adrenocorticotropic hormone and their receptors. The MC system has a role in both pigmentation and the regulation of energy homeostasis, in which MC4R, one of the five MC receptors, has a key role. Interestingly, the barfin flounder (Pleuronectiformes) reared with a black background shows retarded growth compared to white background-reared fish, which could be associated with the MC system because of its dual role in regulating pigmentation and energy status.

Effects of background color on GnRH and MCH levels in the barfin flounder brain.

Effects of background color on gonadotropin-releasing hormone (GnRH) and melanin-concentrating hormone (MCH) levels in the brain of the barfin flounder Verasper moseri were monitored to investigate the interaction of GnRH and MCH in the brain. Fish were reared in white or black tanks from one month after hatching for about 7 months. MCH levels in the brain and pituitary were higher in the white tank fish.

The melanin-concentrating hormone receptor 2 (MCH-R2) mediates the effect of MCH to control body color for background adaptation in the barfin flounder.

Melanin-concentrating hormone (MCH) is a neuropeptide generated in neurons originating in the hypothalamus, from which axons project to the entire brain and neurohypophysis in fish. MCH has both central and peripheral roles such as food intake and body color change. Here we cloned two MCH receptors (MCH-R) from the barfin flounder, Verasper moseri, Pleuronectiformes.

Profiles of alpha-melanocyte-stimulating hormone in the Japanese flounder as revealed by a newly developed time-resolved fluoroimmunoassay and immunohistochemistry.

Profiles of alpha-melanocyte-stimulating hormone (alpha-MSH) in the Japanese flounder were examined by a newly developed time-resolved fluoroimmunoassay (TR-FIA) and immunohistochemistry. A TR-FIA for alpha-MSH was newly developed, and its levels in the pituitary gland and plasma of Japanese flounder reared in a white or black tank for 5 months were compared. A competitive assay using two antibodies was performed among secondary antibodies in the solid phase, alpha-MSH antibodies, samples, and europium-labeled Des-Ac-alpha-MSH.

Expression of three proopiomelanocortin subtype genes and mass spectrometric identification of POMC-derived peptides in pars distalis and pars intermedia of barfin flounder pituitary.

Proopiomelanocortin (POMC) is a common precursor of adrenocorticotropic hormone (ACTH), melanophore-stimulating hormone (MSH), and endorphin (END). In pituitary gland, POMC receives posttranslational processing by which different peptides are generated in the pars distalis (PD) and pars intermedia (PI). Recently, we cloned three subtypes of the POMC gene in pituitary gland of barfin flounder.

Effects of tank color on melanin-concentrating hormone levels in the brain, pituitary gland, and plasma of the barfin flounder as revealed by a newly developed time-resolved fluoroimmunoassay.

A pleuronectiform fish, the barfin flounder Verasper moseri, reared in a white tank had a smaller ratio of pigmented area of the skin on non-eyed side, grew faster, and had greater melanin-concentrating hormone (MCH)-immunoreactive cell bodies and MCH gene expression in the brain than in the black tank, indicating that synthesis and release of MCH are higher in fish from a white tank. In the present study, a time-resolved fluoroimmunoassay for MCH was developed. MCH levels were assessed in the brain, pituitary gland, and plasma of barfin flounders reared in a white or black tank.

Nucleotide sequence and expression of three subtypes of proopiomelanocortin mRNA in barfin flounder.

Melanophore-stimulating hormone (MSH) has been shown to be associated with food intake in addition to body color change in teleosts. MSH is encoded by a proopiomelanocortin (POMC) gene together with endorphin (END). To assess the significance of MSH to biological activities, we determined the structure and evaluated the expression of POMC mRNA in barfin flounder (bf), Verasper moseri, a member of a group of teleosts, Pleuronectiformes.

Immunocytochemical localization and ontogenic development of alpha-melanocyte-stimulating hormone (alpha-MSH) in the brain of a pleuronectiform fish, barfin flounder.

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a pituitary hormone derived by post-translational processing from proopiomelanocortin and is involved in background adaptation in teleost fish. It has also been reported to suppress food intake in mammals. Here, we examined the immunocytochemical localization of alpha-MSH in the brain and pituitary of a pleuronectiform fish, the barfin flounder (Verasper moseri), as a first step in unraveling the possible function of alpha-MSH in the brain.

Differential expression of histochemical characteristics in the developing olfactory receptor cells in a flatfish, barfin flounder (Verasper moseri).

Differentiation of the histochemical characteristics of the olfactory receptor cells (ORC) was examined by immunohistochemistry for protein gene product 9.5 (PGP 9.5) and calretinin (CR) and lectin histochemistry for Phaseolus vulgaris agglutinin-L (PHA-L) in the developing olfactory epithelium (OE) of the barfin flounder.

Variety in histochemical characteristics of the olfactory receptor cells in a flatfish, barfin flounder (Verasper moseri).

Variety in histochemical characteristics of the olfactory receptor cells (ORC) was examined by immunohistochemistry for protein gene product 9.5 (PGP9.5) and calretinin, and by lectin histochemistry with Phaseolus vulgaris leucoagglutinin (PHA-L) in the olfactory epithelium (OE) of the barfin flounder (Verasper moseri).

Morphogenesis of the olfactory pit in a flatfish, barfin flounder (Verasper moseri).

Morphogenesis of the olfactory pit (OP), olfactory lamella (OL) and olfactory epithelium (OE) was examined by scanning electron and light microscopy in the barfin flounder (Verasper moseri). At day 0 after hatch, the OP was already formed. At day 14, the cellular differentiation of the OE was prominent.

Possible involvement of melanin-concentrating hormone in food intake in a teleost fish, barfin flounder.

We investigated the involvement of MCH in food intake in barfin flounder. The structure of barfin flounder MCH was determined by cDNA cloning and mass spectrometry. In fasted fish, the MCH gene expression and the number of MCH neurons in the brain were greater than controls.

Changes in brain GnRH mRNA and pituitary GnRH peptide during testicular maturation in barfin flounder.

The pleuronectid barfin flounder (Verasper moseri) expresses three forms of gonadotropin-releasing hormone (GnRH) in the brain. To clarify the physiological roles of the respective forms during testicular maturation, changes in brain GnRH mRNA levels and pituitary GnRH peptide levels were examined by real-time quantitative PCR and time-resolved fluoroimmunoassay, respectively. Fish hatched in April 2000.

Ontogenic development of three GnRH systems in the brain of a pleuronectiform fish, barfin flounder.

A pleuronectiform fish, the barfin flounder Verasper moseri, has three molecular forms of gonadotropin-releasing hormone (GnRH) in the brain, salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II) and seabream GnRH (sbGnRH). To elucidate the ontogenic origin of the neurons that produce these GnRH molecules, the development of three GnRH systems was examined by in situ hybridization and immunocytochemistry. Neuronal somata that express sGnRH mRNA were detected first in the vicinity of the olfactory epithelium 21 days after hatching (Day 21), and then in the transitional area between the olfactory nerve and olfactory bulb and the terminal nerve ganglion on Day 28.

Immunocytochemical localization and ontogenic development of melanin-concentrating hormone in the brain of a pleuronectiform fish, the barfin flounder.

Melanin-concentrating hormone (MCH) was first discovered in the pituitary of chum salmon because of its role in the regulation of skin pallor. Later, it was found that MCH could also play a role as a central neurotransmitter or neuromodulator in the brain. However, knowledge of the function of MCH in fish has been restricted to certain fish species.

Three GnRH systems in the brain and pituitary of a pleuronectiform fish, the barfin flounder Verasper moseri.

To clarify the possible function of gonadotropin-releasing hormone (GnRH) in the brain of a pleuronectiform fish, the barfin flounder Verasper moseri, the distribution of three forms of GnRH in various areas of the brain was examined by radioimmunoassay, and the localization of GnRH-immunoreactive (ir) cell bodies and fibers in the brain and pituitary was determined by immunocytochemistry. The dominant form in the pituitary was seabream GnRH (sbGnRH), levels of which were much higher than those of salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II). In contrast, sbGnRH levels were extremely low in all other brain areas examined.