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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 &alpha, melanocyte-stimulating hormone (&alpha, MSH)-induced TYR expression was evaluated in B16F10 melanoma cells. SEE attenuated &alpha, 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 &alpha, MSH-induced Pax3 expression. The collective results indicate that SEE attenuates &alpha, 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.

Hsien-Hao Huang,1,2 Liang-Yu Chen,3,4 Ming-Luen Doong,5 Shi-Chuan Chang,6,7 Chih-Yen Chen8–10 1Institute of Clinical Medicine, National Yang-Ming University of Medicine, 2Department of Emergency Medicine, Taipei Veterans General Hospital, 3Aging and Health Research Center, National Yang-Ming University, 4Center for Geriatrics and Gerontology, Taipei Veterans General Hospital, 5Institute of Physiology, National Yang-Ming University School of Medicine, 6Institute of Emergency and Critical Medicine, National Yang-Ming University School of Medicine, 7Department of Chest Medicine, Taipei Veterans General Hospital, 8Division of Gastroenterology and Hepatology, Department of Medicine, Taipei Veterans General Hospital, 9Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, 10Taiwan Association for the Study of Small Intestinal Diseases, Guishan, Taiwan Background: Acyl ghrelin-induced intake depends on hypothalamic neuropeptide Y and agouti-related protein (AgRP) neurotransmitters. Intracerebroventricular (ICV) injection of AgRP increases feeding through competitive antagonism at melanocortin receptors. ICV administration of α-melanocyte stimulating hormone (α-MSH), a natural antagonist of AgRP, may modulate the acyl ghrelin-induced orexigenic effect.Objective: This study aimed to investigate the modulating effect of α-MSH on the central acyl ghrelin-induced food intake, gastrointestinal motility, and colonic secretion in rats.Methods and procedures: We examined the effects of α-MSH and acyl ghrelin on food intake, gastric emptying, small intestinal transit, colonic motility, and secretion in conscious rats with a chronic implant of ICV catheters.Results: ICV injection of O-n-octanoylated ghrelin (0.1 nmol/rat) significantly increased the cumulative food intake up to 8 h (P

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 alpha-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 100 microg) 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 (50 microg) 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.

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.

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.

The effects of 2-mercapto-1-(β-4-pyridethyl) benzimidazole (MPB), one of the benzimidazole derivatives designed for a nucleic acid analogue, on melanogenesis of murine B16-F10 melanoma cell lines were investigated. MPB (40 μM) induced a striking dendricity in B16 melanoma cells within 12 h and maximal dendricity between 48 and 72 h. The stimulation of melanin synthesis was observed after only 2 days of treatment together with a dose-dependent growth inhibition. Moreover, MPB increased the activity of tyrosinase through the expression of tyrosinase mRNA without increasing the intracellular cyclic AMP content. MPB-induced melanogenesis was inhibited by novel protein kinase A inhibitors, KT-5720 and H-85. These findings indicate that MPB stimulated B16 cells to terminally differentiate and may be a useful drug in studying the regulation of melanogenesis.

Monocytes/macrophages are the first cells involved in inflammation. alpha-Melanocyte-stimulating hormone (alpha-MSH) is known to possess an anti-inflammatory role induced by a variety of stimuli; however, the molecular mechanisms underlying these effects are not clearly defined. In this report we provide evidence that alpha-MSH inhibited serum-activated lipopolysaccharide (SA-LPS)-induced proteolytic enzyme release, oxidative burst response, reactive oxygen intermediate generation, nitric oxide production, and adhesion molecule expression in monocyte-derived macrophages. alpha-MSH also inhibited SA-LPS-induced nuclear transcription factor kappaB activation not only in macrophages, but also in a T-cell line and human neutrophils isolated from fresh blood. alpha-MSH downregulated CD14, but not interleukin-1 receptor, tumor necrosis factor receptor 1 or 2 from the surface of macrophages. Anti-CD14 antibody was unable to protect alpha-MSH-mediated downregulation of CD14. Overall, our results suggest that alpha-MSH exerts its anti-inflammatory effect by a novel mechanism in macrophages through downregulating of the endotoxin receptor CD14.

The aim of the present study was to investigate the effect of metabotropic glutamate receptor (mGluR) activation on gamma-aminobutyric acid (GABA) and α-melanocyte stimulating hormone (α-MSH) release from hypothalamic fragments and posterior pituitaries. The actions of a number of subtype-selective mGluR agonists were monitored. A group I mGluR agonist, (S)-3-hydroxyphenylglycine (3-HPG; 0.5 mM), decreased K+-induced hypothalamic GABA release. (RS)-1-Aminoindan-1,5-dicarboxylic acid (AIDA), a specific group I mGluR antagonist (0.2 mM), blocked the effect of 3-HPG. (2S, 1′S, 2′S)-2-(Carboxycyclopropyl) glycine (L-CCG-I) and L-serine-O-phosphate (L-SOP; 0.01-1 mM), agonists of group II and III mGluRs, respectively, did not modify hypothalamic evoked GABA release. Group I mGluR activation decreased, whereas group III increased and group II induced no changes in GABA release from the posterior pituitary. 3-HPG (1 mM) and L-CCG-I (0.1 mM) decreased, whereas L-SOP (0.01-0.1 mM) did not change α-MSH release from hypothalamic fragments. No agonists of the three mGluR groups modified α-MSH release from the posterior pituitary. These results indicate that activation of mGluRs differentially affects GABA and α-MSH release from the hypothalamus and the posterior pituitary. Fil: Pampillo, Macarena. Centro de Investigaciones En Reproducción; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: Scimonelli, Teresa Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Farmacología Experimental de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Farmacología Experimental de Córdoba; Argentina Fil: Duvilanski, Beatriz Haydee. Universidad Abierta Interamericana. Facultad de Medicina. Centro de Altos Estudios en Ciencias de la Salud; Argentina Fil: Celis, María Ester. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacología; Argentina Fil: Seilicovich, Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentina Fil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentina

Chromaffin cells from adult bovine adrenal medulla were found to develop neurites when cocultured with pituitary intermediate lobe (IL) cells. In coculture 51.7% of the chromaffin cells extended neurites compared with 12% in control cultures (chromaffin cells alone). A soluble factor released by IL cells was apparently involved as medium conditioned by contact with IL cells also promoted neurite outgrowth. Moreover, the addition of alpha MSH, one of the pro-opiomelanocortin-derived peptides secreted by IL cells, alone reproduced this effect in a dose-dependent manner. The data provide evidence for a neurotrophic role of alpha MSH.

Tyrosinase induction in murine malignant melanocytes by alpha MSH is well known, but its molecular basis has not been characterized. Treatment of B16 melanoma cells with theophylline or alpha MSH mediates a larger induction of tyrosine hydroxylase than of dopa oxidase activity in total cell extracts, and in the melanosomal and microsomal fractions. No evidence for the modulation of a tyrosinase effector was found. SDS-PAGE and specific activity stain demonstrated two forms of tyrosinase, with different degrees of induction by theophylline. These results agree with the recent proposal that two tyrosinases, encoded by different genes, are present in murine melanocytes.

Similar to melanocyte stimulating hormone (alpha-MSH), its potent and long-acting analogue, [Nle(4), D-Phe(7)]alpha-MSH, when labeled with the paramagnetic amino acid probe 2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid (Toac), maintains its full biological potency, thus validating any comparative structural investigations between the two labeled peptides. Correlation times, calculated from the electron paramagnetic resonance signal of Toac bound to the peptides, and Toac-Trp distances, estimated from the Toac fluorescence quenching of the Trp residue present in the peptides, indicate a more rigid and folded structure for the potent analogue as compared to the hormone, in aqueous medium.

The ACTH/MSH melanocortin core peptide sequence possesses neurotrophic properties in peripheral nerve. During functional neuroanatomical recovery after damage to peripheral nerves, Schwann cells play a significant role in facilitating regeneration. Here we employ a modified super-potent alpha-MSH analogue to solubilise alpha-MSH receptor proteins from cultured primary rat Schwann cells. [125I-Tyr2,Nle4,D-Phe7,ATB-Lys11]-alpha-MSH photoaffinity labelled proteins from Schwann cells were analyzed by SDS-PAGE followed by autoradiography. The results indicate that the alpha-MSH receptor proteins labelled have a molecular weight of 42-45 kDa. These data are the first to demonstrate solubilisation and characterisation of alpha-MSH receptors from non-melanoma cells.

Activation of p38 or p44/42 mitogen-activated protein (MAP) kinases has been shown to trigger differentiation in a number of cell types. The present study has investigated the roles of these kinases in the alpha-melanocyte stimulating hormone (alpha-MSH)-induced melanogenic and proliferative responses in B16 melanoma cells. Treatment of cells with alpha-MSH led to the time-dependent phosphorylation of both p38 and p44/42 MAP kinases. However, only inhibition of p38 MAP kinase activity with SB 203580 blocked both the alpha-MSH-induced melanogenic and anti-proliferative effects. It therefore appears that activation of the p38 pathway can promote melanogenesis and inhibit growth of B16 melanoma cells.