Search

The physiological role of α‐melanocyte stimulating hormone in regulating integumental pigmentation of many vertebrate species has been recognized since the 1960's. However, its physiological significance for human pigmentation remained enigmatic until the 1990's. α‐Melanocyte stimulating hormone and related melanocortins are synthesized locally in the skin, primarily by keratinocytes, in addition to the pituitary gland, and therefore act as paracrine factors for melanocytes. Human melanocytes express the melanocortin 1 receptor, which recognizes α‐melanocyte stimulating hormone and the related adrenocorticotropic hormone as agonists. This review summarizes the current knowledge of the pleotropic effects of the activated melanocortin 1 receptor that maintain human melanocyte homeostasis by regulating melanogenesis and the response to environmental stressors, mainly solar radiation. Certain allelic variants of the melanocortin 1 receptor gene are associated with specific pigmentary phenotypes in various human populations. Variants associated with red hair phenotype compromise the function of the encoded receptor. Activation of the human melanocortin 1 receptor regulates eumelanin synthesis and enhances DNA damage response of melanocytes to solar radiation and oxidative stressors. We describe how synthetic selective melanocortin 1 receptor agonists can be efficacious as sunless tanning agents, for treatment of vitiligo and photosensitivity disorders, and for prevention of skin cancer, including melanoma. [ABSTRACT FROM AUTHOR]

In an attempt to develop potent and non-toxic antimicrobial agent, the palmitoylated analogue of α-melanocyte stimulating hormone(11–13), Pal-α-MSH(11–13) was conjugated with gold nanoparticles (GNPs) for the first time and the efficacy of derived complex was investigated against two strains of Staphylococccus aureus. The GNPs were synthesized using tri-sodium citrate as reductant and Pal-α-MSH(11–13) was conjugated thereafter. The particles were characterised by UV-vis spectroscopy, transmission electron microscopy, dynamic light scattering, fourier transform infrared spectroscopy etc. Conjugation occurred via electrostatic interaction between anionic GNPs and cationic Pal-α-MSH(11–13). The zeta potential of GNP-Pal-α-MSH(11–13) was − 26.91, indicating its stability. The antibacterial activity was determined by minimal inhibitory concentration (MIC) and killing kinetics assay, whereas, inhibition of biofilm formation was studied by determining the biofilm biomass by crystal violet dye binding method, viability of biofilm-embedded cells by counting CFUs and metabolic activity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The toxicity was analysed by hemolysis assay against murine RBCs and cytotoxicity against 3T3 fibroblasts. The MIC was 18 µM for GNP-Pal-α-MSH(11–13) and 12 µM for Pal-α-MSH(11–13). The killing kinetics and biofilm inhibition studies indicated the comparable efficacy of peptide before and after nano-conjugation. Importantly, the conjugation resulted in diminished toxicity, as evidenced by 0.29 ± 0.03% hemolysis and 100% viable fibroblasts at 72 µM compared to the Pal-α-MSH(11–13), showing 74.99 ± 1.59% hemolysis and 59.39 ± 1.06% viable fibroblasts. The nano-fabrication drastically reduced the peptide toxicity without compromising its antibacterial efficacy. The anionicity of the conjugate may be responsible for non-toxicity that makes them suitable for pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Summary: Melanopsin photopigments, Opn4x and Opn4m, were evolutionary selected to “see the light” in systems that regulate skin colour change. In this review, we analyse the roles of melanopsins, and how critical evolutionary developments, including the requirement for thermoregulation and ultraviolet protection, the emergence of a background adaptation mechanism in land‐dwelling amphibian ancestors and the loss of a photosensitive pineal gland in mammals, may have helped sculpt the mechanisms that regulate light‐controlled skin pigmentation. These mechanisms include melanopsin in skin pigment cells directly inducing skin darkening for thermoregulation/ultraviolet protection; melanopsin‐expressing eye cells controlling neuroendocrine circuits to mediate background adaptation in amphibians in response to surface‐reflected light; and pineal gland secretion of melatonin phased to environmental illuminance to regulate circadian and seasonal variation in skin colour, a process initiated by melanopsin‐expressing eye cells in mammals, and by as yet unknown non‐visual opsins in the pineal gland of non‐mammals. [ABSTRACT FROM AUTHOR]

[Display omitted] • Female mice consume more alcohol and saccharin than male mice. • Chemogenetic manipulation of POMC neurons does not affect alcohol consumption. • Chemogenetic manipulation of POMC neurons does not affect saccharin consumption. • Chemogenetic manipulation of POMC neurons alters POMC-derived peptide expression. The endogenous opioid system has been implicated in the rewarding and reinforcing effects of alcohol. Pro-opiomelanocortin (POMC) neurons located within the arcuate nucleus of the hypothalamus (ArcN) secrete multiple peptides associated with alcohol consumption, including β-endorphin (β-END), α-melanocyte stimulating hormone (α-MSH), and adrenocorticotropic hormone (ACTH). In this study, we utilized chemogenetics to bidirectionally modulate ArcN POMC neurons to determine their role in alcohol and saccharin consumption and regional levels of POMC-derived peptides. Male and female POMC-cre mice were infused with viral vectors designed for cre-dependent expression of either excitatory and inhibitory DREADDs or a control vector into the ArcN. Following recovery, animals were allowed to consume alcohol or saccharin using the drinking-in-the-dark (DID) paradigm of binge-like intake for 4 consecutive days. Prior to the final test session, animals were injected with clozapine-N-oxide (2.5 mg/kg, i.p.) for DREADD activation. Following the last DID session, animals were euthanized and the ArcN, VTA, amygdala and NAc were dissected and assessed for POMC peptide expression utilizing western blotting. We found that female mice consumed more alcohol than males during DID sessions 2–4, and that chemogenetic activation had no effect on alcohol or saccharin consumption in either sex. We found that β-END expression within the ArcN positively correlated with alcohol consumption. Given the molecular and functional heterogeneity of ArcN POMC neurons, future studies are needed to assess the effects of modulation of specific subpopulations of these neurons within the ArcN on consumption of rewarding substances such as alcohol and saccharin. [ABSTRACT FROM AUTHOR]

In Alzheimer's disease (AD), appropriate excitatory-inhibitory balance required for memory formation is impaired. Our objective was to elucidate deficits in the inhibitory GABAergic system in the TgCRND8 mouse model of AD to establish a link between GABAergic dysfunction and cognitive function. We sought to determine whether the neuroprotective peptide α-melanocyte stimulating hormone (α-MSH) attenuates GABAergic loss and thus improves cognition. TgCRND8 mice with established β-amyloid peptide pathology and nontransgenic littermates were treated with either α-MSH or vehicle via daily intraperitoneal injections for 28 d. TgCRND8 mice exhibited spatial memory deficits and altered anxiety that were rescued after α-MSH treatment. The expression of GABAergic marker glutamic acid decarboxylase 67 (GAD67) and the number of GABAergic GAD67 α interneurons expressing neuropeptide Y and somatostatin are reduced in the hippocampus in vehicle-treated TgCRND8 mice. In the septohippocampal pathway, GABAergic deficits are observed before cholinergic deficits, suggesting that GABAergic loss may underlie behavior deficits in vehicle-treated TgCRND8 mice. α-MSH preserves GAD67 expression and prevents loss of the somatostatin-expressing subtype of GABAergic GAD67 α inhibitory interneurons. Without decreasing β-amyloid peptide load in the brain, α-MSH improves spatial memory in TgCRND8 mice and prevents alterations in anxiety. α-MSH modulated the excitatory-inhibitory balance in the brain by restoring GABAergic inhibition and, as a result, improved cognition in TgCRND8 mice. [ABSTRACT FROM AUTHOR]

We have discovered a new α-melanocyte stimulating hormone (α-MSH)/peroxisome proliferator activated receptor-γ (PPAR-γ) connection in B16-F10 cells. Both PPAR-γ up-regulation and its induction as an active transcription factor were observed in response to α-MSH. The α-MSH/PPAR-γ connection influenced both pigmentation and proliferation. The forskolin-stimulated cAMP/PKA pathway was not able to induce either PPAR-γ translocation into the nucleus or PPAR-γ transcriptional activity. As the melanocortin-1 receptor, the specific receptor for the α-MSH, is a G-protein coupled receptor, we wondered whether the phosphatidylinositol [PI(4,5)P2/PLCβ] signal pathway was involved in mediating the α-MSH-dependent PPAR-γ activation. Employing inhibitors of PI(4,5)P2/PLCβ pathway, the results of our experiments suggested that this pathway was promoted by α-MSH and that α-MSH played a role in mediating PPAR-γ activation. We have demonstrated, for the first time, that α-MSH induces the PI(4,5)P2/PLCβ pathway, through analysis of the basic steps of the pathway. The α-MSH effect on PPAR-γ was independent of animal species and was not correlated with the physio-pathological status. [ABSTRACT FROM AUTHOR]

Abstract: Neuropeptides released by hypothalamic neurons play a major role in the regulation of feeding, acting both within the hypothalamus, and at other appetite regulating centres throughout the brain. Where classical neurotransmitters signal only within synapses, neuropeptides diffuse over greater distances affecting both nearby and distant neurons expressing the relevant receptors, which are often extrasynaptic. As well as triggering a behavioural output, neuropeptides also act as neuromodulators: altering the response of neurons to both neurotransmitters and circulating signals of nutrient status. The mechanisms of action of hypothalamic neuropeptides with established roles in feeding, including melanin-concentrating hormone (MCH), the orexins, α-melanocyte stimulating hormone (α-MSH), agouti-gene related protein (AgRP), neuropeptide Y, and oxytocin, are reviewed in this article, with emphasis laid on both their effects on appetite regulating centres throughout the brain, and on examining the evidence for their physiological roles. In addition, evidence for the involvement of several putative appetite regulating hypothalamic neuropeptides is assessed including, ghrelin, cocaine and amphetamine-regulated transcript (CART), neuropeptide W and the galanin-like peptides. This article is part of a Special Issue entitled ‘Central control of Food Intake’. [Copyright &y& Elsevier]

Abstract: In rodents, the mediobasal hypothalamus and the hypothalamic paraventricular nucleus (PVN) are implicated in leptin signaling. Surprisingly little data is available on the human hypothalamus. We set out to study the expression of suppressor-of-cytokine-signaling 3 (SOCS3), α-melanocyte stimulating hormone (αMSH) and agouti-related protein (AgRP) in the infundibular nucleus (IFN) and to investigate the relationship between these neuropeptide expressions and serum leptin concentrations in a blood sample taken within 24h before death. We studied post-mortem human brain material by means of quantitative immunocytochemistry. We found that SOCS3 immunoreactivity was widely distributed throughout the hypothalamus, and most prominent in the PVN, whereas expression levels in the IFN were low. Surprisingly, SOCS3 expression in the PVN was inversely related to serum leptin. A significant positive correlation was observed between AgRP and NPY expression in the IFN. The inverse correlation between SOCS3 expression in the PVN and serum leptin was unexpected and may be related to the hypothalamic adaptation to fatal illness rather than to nutritional status, or may represent an interspecies difference. [Copyright &y& Elsevier]

Abstract: Subarachnoid hemorrhage (SAH) is still a major cause of morbidity and mortality. α-Melanocyte stimulating hormone (α-MSH) and other melanocortin peptides exert potent neuroprotective action and they might modulate key molecules involved in SAH-induced vasospasm. The aim of this research was to determine whether treatment with the α-MSH analog Nle4,DPhe7-α-MSH (NDP-MSH) exerts protective effects in experimental SAH in the rat. Initial experiments examined effects of NDP-MSH on the basilar artery phenotype in the absence of injury. In these tests intrathecal injection of small concentrations (10ng) of the peptide induced a tolerant phenotype similar to that observed after ischemic preconditioning. Then the effect of systemic treatment with NDP-MSH (100μg i.v.) on experimental SAH was evaluated. SAH was induced by a single-blood injection into the cisterna magna. The basilar artery phenotype was examined at 4h and the artery caliber at 5days following SAH. Expression of 96 genes was analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) using Custom Taqman Low-Density Arrays. Four hours after SAH, the transcriptional profile of the basilar artery was deeply disrupted. Transcript alteration included genes involved in inflammation, stress response, apoptosis, and vascular remodeling. Treatment with NDP-MSH prevented most of these transcription changes and decreased phosphorylation of extracellular-signal-regulated kinases (ERK1/2) and inhibitor protein IκBα. Vasospasm on day 5 was significantly reduced by NDP-MSH administration. These results combine with others on CNS inflammation to suggest that the melanocortins could be safe and effective therapeutic candidates to treat SAH-related complications. [Copyright &y& Elsevier]

Abstract: Chalcone type compound 1a ((E)-6′-benzylidene-4a′-methyl-4′,4a′,7′,8′-tetrahydro-3′H-spiro[[1,3]dithiolane-2,2′-naphthalen]-5′(6′H)-one) was discovered as an potent inhibitor in melanogenesis. To define its structure–activity relationship, a series of analogs 1b–n, dithiolane truncated 2a–b and ring A removed 3a–e were prepared and evaluated. The electron donating substitution on the phenyl ring (ring C) rather than an electron withdrawing group and dithiolane motif of 1 are needed for the activity enhancement. The scaffold containing both rings A and B associated with α,β-unsaturated system connected to phenyl of 1 was essential for antimelanogenesis. [Copyright &y& Elsevier]

Abstract: Obesity is associated with increased risk of diabetes, cardiovascular disease and several types of cancers. The hypothalamus is a region of the brain critical in the regulation of body weight. One of the critical and best studied hypothalamic circuits is comprised of the melanocortinergic orexigenic agouti-related protein (AgRP) and anorexigenic α-melanocyte stimulating hormone (α-MSH) neurons. These neurons project axons to the same hypothalamic target neurons and balance each other''s activity leading to body weight regulation. We previously showed that the brain proteoglycan syndecan-3 regulates feeding behavior and body weight, and syndecan-3 null (SDC-3−/−) mice are lean and obesity resistant. Here we show that the melanocortin agonist Melanotan II (MTII) potently suppresses food intake and activates the hypothalamic paraventricular nuclei (PVN) in SDC-3−/− mice based on c-fos immunoreactivity. Interestingly, we determined that the AgRP neuropeptide is reduced in the PVN of SDC-3−/− mice compared to wild type mice. In contrast, neuropeptide Y, coexpressed in the AgRP neuron, is not differentially expressed nor is the counteracting neuropeptide α-MSH. These findings are unprecedented and indicate that AgRP protein localization can be selectively regulated within the hypothalamus resulting in altered neuropeptide response and tone. [Copyright &y& Elsevier]

Abstract: Norepinephrine (NE), synthesized in both the central and peripheral nervous system, is involved in food intake regulation of both mammals and chickens. Neuropeptide Y (NPY), a potent orexigenic peptide, is colocalized with NE neurons in the central and peripheral nervous system, suggesting an interaction. Proopiomelanocortin (POMC) is the precursor of α-melanocyte stimulating hormone, a potent anorexigenic peptide synthesized in the hypothalamus. In this study, two experiments were conducted to examine the effect of intracerebroventricular (ICV) injection of NE on appetite mediators in neonatal chicks (Gallus gallus). Experiment 1 was done to confirm the effect of centrally administered NE (0, 25, 50, and 100μg) on food intake following a 3h fast, and to determine the change in NPY mRNA expression in the central nervous system (CNS). In Experiment 2, chicks fed ad libitum were treated ICV with NE (50μg) to determine if changes occurred in brain NPY and POMC mRNA levels. In Experiment 1, the ICV injection of NE dose-dependently reduced food intake, but there was no change in NPY mRNA expression in the CNS. In Experiment 2, there was no significant change in NPY and POMC mRNA expression between the control and NE-treated group, indicating that ICV injection of NE may not be associated with changes in NPY or POMC gene expression. [Copyright &y& Elsevier]

Abstract: Novel 3,4-dihydroquinazoline-2(1H)-thiones (QNTs) 1 were found to be potent inhibitors of α-MSH-induced melanin production. The effect of QNTs to inhibit melanin formation in B16 melanoma cells was screened in the presence of α-MSH. In defining the mechanism of activity, the effects on tyrosinase activity, on tyrosinase synthesis and on the depigmentation of melanin were evaluated. QNTs did not affect the catalytic activity of tyrosinase, but rather acted as an inhibitor of tyrosinase synthesis. [Copyright &y& Elsevier]

Exercise is a mechanism for maintenance of body weight in humans. Morbidly obese human patients have been shown to possess single nucleotide polymorphisms in the melanocortin-4 receptor (MCAR). MC4R knockout mice have been well characterized as genetic: model that possesses phenotypic metabolic disorders, including obesity, hyperphagia, hyperinsulinemia, and hyperleptinemia, similar to those observed in humans possessing dysfunctional hMC4Rs. Using this model, we examined the effect of voluntary exercise MC4R knockout mice that were allowed access to running wheel for a duration of 8 wk. Physiological parameters that were measured included body weight, body composition of fat and lean mass, food consumption, body length, and blood levels of cholesterol and nonfasted glucose, insulin, and leptin. At the termination of the experiment, hypothalamic mRNA expression levels of neuropeptide Y (NPY), agouti-related protein (AGRP), proopiomelanocorlin (POMC), cocaine- and amphetamine-regulated transcript (CART), orexin, brain-derived neurotropic factor (BDNF), phosphatase with tensin homology (Pten), melanocortin-3 receptor (MC3R), and NPY-Y1R were determined. In addition, islet cell distribution and function in the pancreas were examined. In the exercising MC4R knockout mice, the pancreatic islet cell morphology and other physiological parameters resembled those observed in the wild-type littermate controls. Gene expression profiles identified exercise as having a significant effect on hypothalamic POMC, orexin, and MC3R levels. Genotype had a significant effect on AGRP, POMC, CART, and NPY-Y1R, with an exercise and genotype interaction effect on NPY gene expression. These data support the hypothesis that voluntary exercise can prevent the genetic predisposition of melanocortin-4 receptor-associated obesity and diabetes. [ABSTRACT FROM AUTHOR]

Abstract: Spongiform degeneration is characterized by vacuolation in nervous tissue accompanied by neuronal death and gliosis. Although spongiform degeneration is a hallmark of prion diseases, this pathology is also present in the brains of patients suffering from Alzheimer’s disease, diffuse Lewy body disease, human immunodeficiency virus (HIV) infection, and Canavan’s spongiform leukodystrophy. The shared outcome of spongiform degeneration in these diverse diseases suggests that common cellular mechanisms must underlie the processes of spongiform change and neurodegeneration in the central nervous system. Immunohistochemical analysis of brain tissues reveals increased ubiquitin immunoreactivity in and around areas of spongiform change, suggesting the involvement of ubiquitin–proteasome system dysfunction in the pathogenesis of spongiform neurodegeneration. The link between aberrant ubiquitination and spongiform neurodegeneration has been strengthened by the discovery that a null mutation in the E3 ubiquitin–protein ligase mahogunin ring finger-1 (Mgrn1) causes an autosomal recessively inherited form of spongiform neurodegeneration in animals. Recent studies have begun to suggest that abnormal ubiquitination may alter intracellular signaling and cell functions via proteasome-dependent and proteasome-independent mechanisms, leading to spongiform degeneration and neuronal cell death. Further elucidation of the pathogenic pathways involved in spongiform neurodegeneration should facilitate the development of novel rational therapies for treating prion diseases, HIV infection, and other spongiform degenerative disorders. [Copyright &y& Elsevier]

Abstract: The melanocortin 1 receptor (MC1R) is a dimeric G protein-coupled receptor expressed in melanocytes, where it regulates the amount and type of melanins produced and determines the tanning response to ultraviolet radiation. We have studied the mechanisms of MC1R dimerization. Normal dimerization of a deleted mutant lacking the seventh transmembrane fragment and the C-terminal cytosolic extension excluded coiled-coil interactions as the basis of dimerization. Conversely, the electrophoretic pattern of wild type receptor and several Cys→Ala mutants showed that four disulfide bonds are established between the monomers. Disruption of any of these bonds abolished MC1R function, but only the one involving Cys35 was essential for traffic to the plasma membrane. A quadruple Cys35–267–273–275Ala mutant migrating as a monomer in SDS–PAGE in the absence of reducing agents was able to dimerize with WT, suggesting that in addition to disulfide bond formation, dimerization involves non-covalent interactions, likely of domain swap type. [Copyright &y& Elsevier]

Early detection of primary melanoma tumors is essential because there is no effective treatment for metastatic melanoma. Several linear and cyclic radiolabeled α-melanocyte stimulating hormone (α-MSH) analogs have been proposed to target the melanocortin type 1 receptor (MC1R) overexpressed in melanoma. The compact structure of a rhenium-cyclized α-MSH analog (Re-CCMSH) significantly enhanced its in vivo tumor uptake and retention. Melanotan II (MT-II), a cyclic lactam analog of α-MSH (Ac-Nle- cyclo[Asp-His- dPhe-Arg-Trp-Lys]-NH2]), is a very potent and stable agonist peptide largely used in the characterization of melanocortin receptors. Taking advantage of the superior biological features associated with the MT-II cyclic peptide, we assessed the effect of lactam-based cyclization on the tumor-seeking properties of α-MSH analogs by comparing the pharmacokinetics profile of the 99mTc-labeled cyclic peptide βAla-Nle- cyclo[Asp-His- d-Phe-Arg-Trp-Lys]-NH2 with that of the linear analog βAla-Nle-Asp-His- dPhe-Arg-Trp-Lys-NH2 in melanoma-bearing mice. We have synthesized and coupled the linear and cyclic peptides to a bifunctional chelator containing a pyrazolyl-diamine backbone (pz) through the amino group of βAla, and the resulting pz–peptide conjugates were reacted with the fac-[99mTc(CO)3]+ moiety. The 99mTc(CO)3-labeled conjugates were obtained in high yield, high specific activity, and high radiochemical purity. The cyclic 99mTc(CO)3-labeled conjugate presents a remarkable internalization (87.1% of receptor-bound tracer and 50.5% of total applied activity, after 6 h at 37 °C) and cellular retention (only 24.7% released from the cells after 5 h) in murine melanoma B16F1 cells. A significant tumor uptake and retention was obtained in melanoma-bearing C57BL6 mice for the cyclic radioconjugate [9.26 ± 0.83 and 11.31 ± 1.83% ID/g at 1 and 4 h after injection, respectively]. The linear 99mTc(CO)3-pz–peptide presented lower values for both cellular internalization and tumor uptake. Receptor blocking studies with the potent (Nle4, dPhe7)-αMSH agonist demonstrated the specificity of the radioconjugates to MC1R (74.8 and 44.5% reduction of tumor uptake at 4 h after injection for cyclic and linear radioconjugates, respectively). [ABSTRACT FROM AUTHOR]

Abstract: This experiment was conducted to determine the effects of central α-melanocyte stimulating hormone (α-MSH) and its interaction with neuropeptide Y (NPY) on ingestive and non-ingestive behaviors in chicks. Chicks received intracerebroventricular injections of either 0, 0.12 nM α-MSH, 0.06 nM NPY, or 0.12 nM α-MSH+0.06 nM NPY. Immediately following injection, chicks were placed in an observation arena and the number of steps, jumps, feed pecks, drinks, exploratory pecks, escape attempts, the total distance traveled, and the amount of time spent standing, sitting, sleeping, and preening were monitored for 60 min. Chicks treated with NPY consumed 69% more feed than controls whereas α-MSH-treated chicks consumed 71% less. Feed intake of the NPY+α-MSH groups was similar to α-MSH-treated chicks at 66% less than aCSF-treated chicks. Differences in pecking were found and followed a similar pattern as feed intake. All treatments increased the amount of time chicks were in a sitting posture, and the α-MSH+NPY group spent more time sitting than α-MSH and NPY alone. The sitting response after α-MSH+NPY treatment was similar to the α-MSH group but not the NPY group. Other behaviors were not affected by treatment. Thus, we conclude that α-MSH, at a concentration that causes a similar magnitude decrease in feed intake as NPY increases feed intake, is a more potent appetite-related signal than NPY. α-MSH causes behavioral effects that may secondarily affect feed intake at a low magnitude and may modulate the behavioral effects of NPY in chicks, contributing to the overall effect on feed intake. [Copyright &y& Elsevier]

Abstract: Although recent reports underscore a close association between the ethanol consumption and the central melanocortin (MC) system in rats, neurobehavioral component of this association has not been explored. In this study, we investigated the role of α-melanocyte stimulating hormone (α-MSH) in ethanol (1.5–2g/kg, i.p.) induced anxiolysis and anxiety-like behavior following withdrawal from prolonged ethanol (9% v/v ethanol, 15days) consumption, using elevated plus maze (EPM) test in rats. While α-MSH (1–5μg/rat, i.c.v.) showed dose-dependent anxiogenic-like effect, the MC4 receptor antagonist HS014 (1–10nM/rat, i.c.v.) or antiserum against α-MSH (1:500–1:50 dilution, 5μl/rat, i.c.v.) failed to produce any effect in the EPM test. The anxiolytic-like effect of ethanol was suppressed by central administration of α-MSH (0.5μg/rat, i.c.v.). On the other hand, pretreatment with either HS014 (5nM/rat, i.c.v.) or antiserum against α-MSH (1:100 dilution, 5μl/rat, i.c.v.) enhanced anxiolytic action of ethanol. Moreover, ethanol withdrawal anxiety was markedly blocked by HS014 (1–10nM/rat, i.c.v.). These results suggest that α-MSH may be implicated in ethanol-induced anxiolysis and withdrawal anxiety. These findings also suggest MC4 receptors as possible therapeutic target for development of drugs to address the ethanol withdrawal-related conditions. [Copyright &y& Elsevier]

Abstract: Si-multi-electrode arrays implanted into brain tissue for long-term recording lose electrical connectivity due to the post-implantation inflammatory reaction. This inflammatory reaction creates a physical and electrical gap between the electrode and the surrounding neurons. In this study, novel nitrocellulose-based coatings were developed for the sustained delivery of the anti-inflammatory neuropeptide α-melanocyte stimulating hormone (α-MSH). α-MSH was incorporated in micron-scale nitrocellulose coatings and slow, sustained release over 21 days was attained in vitro. The α-MSH released on day 21 was still bioactive, and successfully inhibited nitric oxide (NO) production by LPS-stimulated microglia. The amount of initial drug loading directly affected the release rate, with higher initial loading increasing the mass released but not the percent of drug released. The surface morphology and thickness of the coatings were examined by scanning electron microscopy (SEM) and profilometry. In addition, impedance measurement showed that the α-MSH loaded nitrocellulose coatings reduced the magnitude of electrode impedance at the biologically relevant frequency of 1 kHz. In conclusion, nitrocellulose-based, bioactive coatings that release anti-inflammatory agents without increasing the impedence of the electrode were successfully fabricated. These coatings have the potential to reduce inflammation at the electrode–brain interface in vivo, and facilitate long-term recordings from Si-multi-electrode arrays. [Copyright &y& Elsevier]

Effects of the cocaine- and amphetamine-regulated transcript (CART) peptide on tuberoinfundibular dopaminergic (TIDA) neurons were examined in female and male Sprague–Dawley rats in the morning and afternoon. We also examined the blocking effects of melanin concentrating hormone (MCH) and the antagonists of α-melanocyte stimulating hormone (α-MSH), SHU9119 and HS014, on stimulation induced by the CART peptide in TIDA systems. Intracerebroventricular administration of 1 μg CART peptide (55–102) at 45 min, either in the morning or afternoon, produced an increase in the median eminence (ME) DOPAC (3,4-dihydroxyphenylacetic acid) level and a corresponding decrease in serum prolactin (PRL) levels. This resulted from stimulation of TIDA neurons regardless of castration, and whether or not male and female rats were estrogen-primed. The stimulatory effects of the CART peptide on ME DOPAC levels were similar in the morning and afternoon in both male and female rats. Central treatment with 1 μg SHU9119, HS014, or MCH significantly decreased the ME DOPAC levels and elevated serum PRL levels in female rats. However, only MCH prevented the stimulatory effect of the CART peptide on TIDA neurons. These results indicate that stimulation by the CART peptide on TIDA neurons is gender-independent; and this stimulatory effect can be blocked by MCH, but not the antagonists of α-MSH. [Copyright &y& Elsevier]

Over three experiments, separate groups of adult male Sprague–Dawley rats received intracerebroventricular (ICV) injections of either vehicle, recombinant rat leptin (1μg), or leptin (4μg), then two ICV injections, 30min apart of vehicle/vehicle, leptin (4μg)/vehicle, vehicle/α-MSH (300ng), or leptin/α-MSH, and then vehicle/vehicle, leptin (4μg)/vehicle, vehicle/ SHU-9119 (200ng; a MC 3/4 receptor antagonist), or leptin/SHU-9119. Core temperatures (Tc), food intake and body weights were monitored.Four microgram leptin resulted in the induction of fever, an effect blocked by injection of α-MSH. Antagonism of MC 3/4 receptors with SHU-9119 did not augment leptin-induced fever, but did block the inhibitory actions of leptin on food intake.These data demonstrate the inhibitory effects of exogenous α-MSH on leptin-induced fever, but suggest that endogenous melanocortin action at MC 3/4 receptors does not tonically inhibit febrigenesis caused by leptin administration. [Copyright &y& Elsevier]

EPO and α-MSH prevent ischemia/reperfusion-induced down-regulation of AQPs and sodium transporters in rat kidney. Background. Ischemia-induced acute renal failure (ARF) is known to be associated with significant impairment of urinary concentrating ability and down-regulation of renal aquaporins (AQPs) and sodium transporters in rats. We tested whether treatment with erythropoietin (EPO) or α-melanocyte-stimulating hormone (α-MSH) in combination with EPO reduces the renal ischemia/reperfusion (I/R) injury and prevents the down-regulation of renal AQPs and major sodium transporters. Methods. I/R-induced ARF was established in rats by 40-minute temporary bilateral obstruction of renal arteries, and rats were kept in metabolic cages for urine measurements. After 2 or 4 days following EPO and/or α-MSH treatment, kidneys were removed to determine the expression levels of AQPs and sodium transporters by semiquantitative immunoblotting. Results. Rats with ARF showed significant renal insufficiency, increased urine output, and high fractional excretion of urinary sodium. Consistent with this, immunoblotting and immunocytochemistry revealed that the kidney expression of AQPs (AQP-1, -2 and -3) and sodium transporters [Na,K-ATPase, rat type 1 bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1), Na/H exchanger type 3 (NHE3), and thiazide-sensitive sodium chloride cotransporter (TSC)] in ARF rats was significantly decreased compared to sham-operated control rats. In contrast, EPO treatment at the time of ischemia of rats with ARF significantly prevented the ischemia-induced down-regulation of renal AQPs and sodium transporters and in parallel improved the urinary concentrating capability and renal sodium reabsorption. Importantly, similar effects were observed following the initiation of EPO or α-MSH treatment 4 hours after the onset of ischemia injury. Moreover, the combination of EPO with α-MSH potentiated the beneficial effects of single compound treatment. Conclusion. EPO and/or α-MSH treatment significantly prevent I/R-induced injuries such as urinary-concentrating defects and down-regulation of renal AQPs and sodium transporters. [ABSTRACT FROM AUTHOR]

The melanocortins (α-melanocyte-stimulating hormone and adrenocorticotropin) act on epidermal melanocytes to increase melanogenesis, the eumelanin/pheomelanin ratio and dendricity. These actions are mediated by the heptahelical melanocortin 1 receptor (MC1R), positively coupled to adenylyl cyclase. Gain-of-function mouse Mc1r alleles are associated with a dark, eumelanic coat. Conversely, loss-of-function variants, or overexpression of agouti, a natural melanocortin antagonist, yield yellow, pheomelanic furs. In humans, loss-of-function MC1R variants are associated with fair skin, poor tanning, propensity to freckle and increased skin cancer risk. Therefore, MC1R is a key regulator of mammalian pigmentation. Several observations such as induction of constitutive pigmentation in amelanotic mouse melanoma cells following expression of MC1R indicate that the receptor might display agonist-independent activity. We report a systematic and comparative study of MC1R and Mc1r constitutive activity. We show that expression of MC1R in heterologous systems leads to an agonist-independent increase in cyclic adenosine monophophate (cAMP). Basal signalling is a function of receptor expression and is two to fourfold higher for MC1R than for Mc1r. Moreover, it is observed in human melanoma cells over-expressing the MC1R. Constitutive signalling is abolished or reduced by point mutations of MC1R impairing the response to agonists, and is only doubled by the Lys94Glu mutation, mimicking the constitutively active mouse E so-3 J allele. Stable or transient expression of wild-type MC1R, but not of loss-of-function mutants, potently stimulates forskolin activation of adenylyl cyclase, a common feature of constitutively active Gs-coupled receptors. Therefore, human MC1R displays a strong agonist-independent constitutive activity. [ABSTRACT FROM AUTHOR]

Prostaglandins are potent mediators of the inflammatory response and are also involved in cancer development. In this study, we show that human melanocytes and FM55 melanoma cells express cyclooxygenase-1 and -2 (COX-1 and -2) and thus have the capability to produce prostaglandins. The FM55 cells produced predominantly PGE2 and PGF2α, whereas the HaCaT keratinocyte cell line produced mainly PGE2. The anti-inflammatory peptide, α-melanocyte stimulating hormone (α-MSH), reduced prostaglandin production in FM55 and HaCaT cells and reversed the effect of the pro-inflammatory cytokine TNF-α in the former. These results indicate that melanocytes produce prostaglandins and that α-MSH, by inhibiting this response, may play an important role in regulating inflammatory responses in the skin. [Copyright &y& Elsevier]

We investigated the effect of α-melanocyte stimulating hormone (α-MSH) on cerulein induced acute pancreatitis in rats. α-MSH treatment (50 μg per rat, intraperitoneally) prior to cerulein reduced the plasma amylase level, pancreatic weight, pancreatic myeloperoxidase activity and the severity of the lesions microscopically. These data suggest that α-MSH has a protective effect on cerulein-induced acute pancreatitis and this effect could be attributed, at least in part, to decreased tissue leukocyte infiltration and thus, to decreased pro-inflammatory cytokine production and/or oxygen- and nitrogen-derived reactive metabolite release. [Copyright &y& Elsevier]

We have previously shown α-melanocyte stimulating hormone to protect melanocytes and melanoma cells from the proinflammatory actions of tumor necrosis factor-α. The aim of the study was to extend this work to look into the influence of tumor necrosis factor-α on melanoma cell attachment, invasion, and integrin expression and ask to what extent α-melanocyte stimulating hormone might protect cells from tumor necrosis factor-α stimulation of increased integrin expression. HBL human melanoma cells were studied under resting and stressed conditions using tumor necrosis factor-α as a proinflammatory cytokine. Functional information on the actions of tumor necrosis factor-α on melanoma cells was obtained by examining the strength of attachment of melanoma cells to substrates and the ability of melanoma cells to invade through fibronectin. α3, α4, and β1 integrin expression was detected by Western immunoblotting and the ability of α-melanocyte stimulating hormone to oppose the actions of tumor necrosis factor-α was studied on HBL cell attachment, invasion, and integrin subunit expression. Our results show that tumor necrosis factor-α increases the number of melanoma cells attaching to collagen (types I and IV) and tissue culture polystyrene, increases ability to invade through fibronectin, and upregulates the expression of α3 (28%), α4 (90%), and β1 (65%) integrin subunit expression. In contrast, α-melanocyte stimulating hormone reduced cell attachment, invasion, and integrin expression and opposed the stimulatory effects of tumor necrosis factor-α. In conclusion this study provides further evidence of α-melanocyte stimulating hormone acting to “protect” melanoma cells from proinflammatory cytokine action. Our data support a hypothesis that an inflammatory environment would promote melanoma invasion and that the anti-invasive actions of... [ABSTRACT FROM AUTHOR]

Summary Recently, it has been shown that α-melanocyte stimulating hormone can directly activate tyrosinase by removing the allosteric regulator 6(R)-L-erythro 5,6,7,8 tetrahydrobiopterin resulting in a stable α-melanocyte stimulating hormone/6(R)-L-erythro 5,6,7,8 tetrahydrobiopterin complex. As melanin production occurs in the melanosome, a specific organelle of the melanocyte, it seemed important to investigate whether these organelles themselves actually produce pro-opiomelanocortin-related peptides in their acidic environment. The presence of α-melanocyte stimulating hormone and adrenocorticotropin in the epidermis and melanocytes has been shown by several investigators. In order to follow possible pro-opiomelanocortin processing in the melanosome, human melanocytes were established in MCDB 153 medium and utilized for immunohistochemistry, immunogold electron micro- scopy, and western blotting. For this purpose antibodies against α-melanocyte stimulating hormone, adrenocorticotropin, prohormone convertases 1 and 2 (PC1 and PC2) and the PC2 regulatory protein 7B2 were used. Our results demonstrated the presence of the entire system for pro-opiomelanocortin processing in the melanosome. Considering the pH optima of these convertases, the results are in agreement with an autocrine intramelanosomal production of pro- opiomelanocortin-related peptides and an autocrine production and recycling of the cofactor 6(R)-L- erythro 5,6,7,8 tetrahydrobiopterin in melanocytes. Based on these novel observations, we would like to propose that the pigmentation process may not necessarily involve a melanocortin-1 receptor-mediated mechanism. [ABSTRACT FROM AUTHOR]

Although hypothalamic corticotropin-releasing hormone (CRH) is involved in the stress response in all vertebrate groups, only a limited number of studies on this neuroendocrine peptide deals with non-mammalian neuroendocrine systems. We determined the cDNA sequence of the CRH precursor of the teleost Oreochromis mossambicus (tilapia) and studied the biological potency of the CRH peptide in a homologous teleost bioassay. Polymerase chain reaction (PCR) with degenerate and specific primers yielded fragments of tilapia CRH cDNA. Full-length CRH cDNA (988 nucleotides) was obtained by screening a tilapia hypothalamus cDNA library with the tilapia CRH PCR products. The precursor sequence (167 amino acids) contains a signal peptide, the CRH peptide and a motif conserved among all vertebrate CRH precursors. Tilapia CRH (41 aa) displays between 63% and 80% amino acid sequence identity to CRH from other vertebrates, whereas the degree of identity to members of the urotensin I/urocortin lineage is considerably lower. In a phylogenetic tree, based on alignment of all full CRH peptide precursors presently known, the three teleost CRH precursors (tilapia; sockeye salmon, Oncorhynchus nerka ; white sucker, Catostomus commersoni ) form a monophyletic group distinct from amphibian and mammalian precursors. Despite the differences between the primary structures of tilapia and rat CRH, maximally effective concentrations of tilapia and rat CRH were equally potent in stimulating adrenocorticotropic hormone (ACTH) and α -MSH release by tilapia pituitaries in vitro . The tilapia and salmon CRH sequences show that more variation exists between orthologous vertebrate CRH structures, and teleost CRHs in particular than previously recognized. Whether the structural differences reflect different mechanisms of action of this peptide in the stress response remains to be investigated. [ABSTRACT FROM AUTHOR]

Dry eye (DE) is a chronic, multifactorial ocular surface disease associated with visual disturbance, tear film instability, hyperosmolarity, ocular surface inflammation and damage. Effective intervention is necessary to control this disease. In this study we topically applied α-melanocyte stimulating hormone (α-MSH) on the ocular surface of scopolamine-induced DE rats and found that it promoted tear secretion, reduced tear breakup time and fluorescein sodium staining and increased the number of conjunctival goblet cells. To investigate the mechanism, protein array was conducted, which showed that α-MSH exerted its effects via epithelial growth factor receptor (EGFR) in the JAK-STAT signaling pathway. Furthermore, in vitro experiments showed that α-MSH protected human corneal epithelial cells (hCECs) by maintaining their migration ability and viability and decreasing apoptosis. However, blockade of EGFR abolished these protective effects. Moreover, α-MSH decreased the level of autophagy in benzalkonium chloride (BAC)-stressed hCECs via EGFR. These results demonstrated that α-MSH ameliorated lesions and restored ocular surface functions by upregulating EGFR expression. • The α-melanocyte stimulating hormone exhibits superior therapeutic performance in rat dry eye model. • The α-MSH maintains cell activity and suppresses autophagy in BAC stressed human corneal epithelial cells. • Mechanistically, α-MSH activates both EGFR and JAK pathways in the dry eye corneas and conjunctivas. • The α-MSH-containing eye drop will be hopefully translated into a novel intervention modality to the dry eye. [ABSTRACT FROM AUTHOR]

Lutetium-177 (177Lu) radiolabeled ultrasmall (~6 nm dia.) fluorescent core-shell silica nanoparticles (Cornell prime dots or C′ dots) were developed for improving efficacy of targeted radiotherapy in melanoma models. PEGylated C′ dots were surface engineered to display 10–15 alpha melanocyte stimulating hormone (αMSH) cyclic peptide analogs for targeting the melanocortin-1 receptor (MC1-R) over-expressed on melanoma tumor cells. The 177Lu-DOTA-αMSH-PEG-C′ dot product was radiochemically stable, biologically active, and exhibited high affinity cellular binding properties and internalization. Selective tumor uptake and favorable biodistribution properties were also demonstrated, in addition to bulk renal clearance, in syngeneic B16F10 and human M21 xenografted models. Prolonged survival was observed in the treated cohorts relative to controls. Dosimetric analysis showed no excessively high absorbed dose among normal organs. Correlative histopathology of ex vivo treated tumor specimens revealed expected necrotic changes; no acute pathologic findings were noted in the liver or kidneys. Collectively, these results demonstrated that 177Lu-DOTA-αMSH-PEG-C′ dot targeted melanoma therapy overcame the unfavorable biological properties and dose-limiting toxicities associated with existing mono-molecular treatments. The unique and tunable surface chemistries of this targeted ultrasmall radiotherapeutic, coupled with its favorable pharmacokinetic properties, substantially improved treatment efficacy and demonstrated a clear survival benefit in melanoma models, which supports its further clinical translation. Image 1 • Unique particle surface chemistry yields favorable targeting and pharmacokinetics. • Nanoparticle therapy results in reduced tumor growth and prolonged survival. • Overcomes dose-limiting toxicities associated with existing therapeutics. • Yields improved treatment efficacy and reduced off-target side effects. [ABSTRACT FROM AUTHOR]

• Ethyl acetate fraction from Arctium lappa L. leaf showed an effective antioxidant activity. • Ethyl acetate fraction from Arctium lappa L. leaf showed a tyrosinase inhibitory effect. • Ethyl acetate fraction from Arctium lappa L. leaf indicated a regulatory activity on melanogenesis. • Major compounds were analyzed as rutin and hydroxycinnamic acid. Phenolics obtained from plants as natural compounds have been used in cosmetic industry as potential alternatives to synthetic chemicals due to its excellent antioxidant and whitening effects. This study investigated the possibility of using Arctium lappa L. leaf extracts as cosmetic substances by assessing whitening effects through its antioxidant and physiological activity in B16/F10 melanoma cells. The ethyl acetate fraction from Arctium lappa L. leaf showed the highest total phenolics (216.75 mg gallic acid equivalent (GAE)/g) relative to the other fractions (n -hexane, chloroform, and distilled water). The antioxidant activities of EAFA were evaluated based on 2,2′-azino-bis (3-ethyl benzthiazoline-6-sulfonic acid) diammonium salt (ABTS) /α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing/antioxidant power (FRAP), and malondialdehyde (MDA) inhibitory effects. The whitening effects of EAFA were examined using tyrosinase inhibitory activity and inhibition of α-melanocyte stimulating hormone (α-MSH) -induced melanogenesis in B16/F10 cells. The ethyl acetate fraction from Arctium lappa L. leaf effectively inhibited the tyrosinase activity and decreased melanin contents as following α-MSH stimulation. Based on these results, the inhibitory mechanism of melanogenesis was confirmed by measuring phosphorylated c-Jun N-terminal kinase (p -JNK), microphthalmia-associated transcription factor (MITF), tyrosinase-related protein 1 (TRP-1), and tyrosinase in α-MSH–induced B16/F10 cells. The ethyl acetate fraction from Arctium lappa L. leaf downregulated the levels of p -JNK, MITF, TRP-1, and tyrosinase. Finally, the main compounds of EAFA were analyzed using the ultra-performance liquid chromatography-quadrupole-time-of-flight (UPLC Q-TOF) MS system, and the components were identified as follows: trans-5-caffeoylqunic acid, rutin, kaempferol-3-O-rutinoside, 3,5-di-O-caffeoylqunic acid, and 4,5-di- O -caffeoylqunic acid. [ABSTRACT FROM AUTHOR]

Ultraviolet irradiation-induced hyperpigmentation of the skin is associated with excessive melanin production in melanocytes. Tyrosinase (TYR) is a key enzyme catalyzing the rate-limiting step in melanogenesis. TYR expression is controlled by microphthalmia-associated transcription factor (MITF) expression. Sorghum is a cereal crop widely used in a variety of foods worldwide. Sorghum contains many bioactive compounds and is beneficial to human health. However, the effects of sorghum in anti-melanogenesis have not been well characterized. In this study, the biological activity of sorghum ethanolic extract (SEE) on α-melanocyte-stimulating hormone (α-MSH)-induced TYR expression was evaluated in B16F10 melanoma cells. SEE attenuated α-MSH-induced TYR gene promoter activity through the downregulation of the transcription factor MITF. We found that paired box gene 3 (Pax3) contributes to the maximal induction of MITF gene promoter activity. Further analysis demonstrated that SEE inhibited α-MSH-induced Pax3 expression. The collective results indicate that SEE attenuates α-MSH-induced TYR expression through the suppression of Pax3-mediated MITF gene promoter activity. Targeting the Pax3-MITF axis pathway could be considered a potential strategy to increase the efficacy of anti-melanogenesis. [ABSTRACT FROM AUTHOR]

The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications. [ABSTRACT FROM AUTHOR]