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1.
An Acad Bras Cienc ; 95(1): e20211581, 2023.
Article in English | MEDLINE | ID: mdl-36946809

ABSTRACT

Ectothermic animals present melanin-containing cells in their integument and viscera. Besides cutaneous melanophores, amphibians have melanomacrophages in the hepatic parenchyma and melanocytes in the viscera, which are also present in their testicular stroma. The native melanocyte stimulating hormone (α-MSH) is the main hormone that modulates the color change in melanophores. However, we still know too little about how the α-MSH acts in vivo on visceral melanin-containing cells. In this study, we collected 30 adult males of Physalaemus nattereri (Anura, Leptodactylidae) to evaluate the short-term effects of α-MSH on melanophores, melanocytes and melanomacrophages under light microscopy. For this, we injected 0.05 ml of a single intraperitoneal dose containing 2.5x10-7 mmol/10g of α-MSH, diluted in ringer solution, in five experimental groups with five individuals each one. The different groups were analyzed after 1, 3, 6, 12 and 24h. The control group with five other individuals received only 0.05 ml of ringer solution. The skin pigmentation increased quickly after animals received the hormone α-MSH with the consequent darkening of the body (body darkness). Melanophores, melanocytes and melanomacrophages responded similarly to the test, with an increase in the area containing melanin. However, melanophores and melanomacrophages reached their darkest pigmentation in a shorter period of time in comparison to the testicular melanocytes, probably due to specific metabolic characteristics of each organ. Thus, we verified that the three types of cells, although present in different organs, are responsive to the native hormone α-MSH, which enables us to treat them as a pigmentary system.


Subject(s)
Melanins , alpha-MSH , Male , Animals , Melanins/metabolism , Melanins/pharmacology , alpha-MSH/pharmacology , alpha-MSH/metabolism , Anura , Ringer's Solution/pharmacology , Skin
2.
Acta Cir Bras ; 37(10): e371002, 2022.
Article in English | MEDLINE | ID: mdl-36542040

ABSTRACT

PURPOSE: The active melanocytes in the skin were affected by hormones and ultraviolet (UV) irradiation. Licorice zinc has a whitening effect, which may have a prominent potential in the treatment of pigmented skin disease. METHODS: Modeling chloasma C57BL/6J mice by daily progesterone injection (15 mg/kg) and ultraviolet B (UVB) irradiation (λ = 312 nm, 2 h/day) for 30 days. Then, mice were given 0.65, 1.3, and 2.6 (g/kg) of licorice zinc and tranexamic acid 250 mg daily by oral administration for 14 days, respectively. Hematoxylin and eosin and Fontana-Masson staining, and Western blotting (WB) were performed to test the inhibitory of melanogenesis and activation of c-Jun-N-terminal (JNK)/p38 mitogen-activated protein kinases (MAPK) for licorice zinc. Melanogenesis was induced by α-melanocyte-stimulating hormone in vitro. Cell counting kit-8, melanin content determination, and WB were performed to verify the inhibitory effect of licorice zinc on melanogenesis. RESULTS: The present study showed that licorice zinc decreased melanin formation, cutaneous tissue injury, and the phosphorylation of JNK and P38MAPK, which was caused by UVB irradiation in vivo. In vitro, licorice zinc showed opposite effects from JNK/p38 activator. Meanwhile, tyrosinase-related protein-1, tyrosinase, and microphthalmia-associated transcription factor were decreased too. CONCLUSIONS: Licorice zinc induced a decrease in melanin synthesis by inhibiting the JNK and the P38MAPK signaling pathway, suggesting licorice zinc is a potential agent of anti-chloasma.


Subject(s)
Glycyrrhiza , Melanins , Animals , Mice , Melanins/metabolism , Melanins/pharmacology , MAP Kinase Signaling System , p38 Mitogen-Activated Protein Kinases , Glycyrrhiza/metabolism , Zinc/pharmacology , Mice, Inbred C57BL , Cell Line, Tumor
3.
Can J Microbiol ; 68(7): 493-499, 2022 Jul 01.
Article in English | MEDLINE | ID: mdl-35303412

ABSTRACT

Paraquat (1,10-dimethyl-4,4-bipyridinium dichloride; PQ) is a free-radical producing herbicide that affects cell membranes and can upset the environmental balance of microorganisms present in soil, such as Cryptococcus spp. This study aimed to evaluate the in vitro activity of PQ against Cryptococcus spp. in planktonic and biofilm forms, as well as the protective effect of antioxidant agents against the antifungal effect of PQ and the kinetics of melanin production in response to PQ. Susceptibility to PQ was evaluated by microdilution. Cryptococcus sp. strains exposed to PQ were grown in media with ascorbic acid (AA) and glutathione (GSH). Melanin production was assessed in the presence of l-3,4-dihydroxyphenylalanine (l-DOPA) + PQ. The minimum inhibitory concentration of PQ against Cryptococcus spp. ranged from 8 to 256 µg/mL. Furthermore, PQ reduced biofilm formation. AA and GSH restored the fungal growth of Cryptococcus spp. exposed to PQ. In addition, l-DOPA + PQ delayed melanin production by 24 and 48 h for C. deuterogattii and C. neoformans sensu lato, respectively, suggesting that PQ induces a fitness trade-off in melanin production. Taken together, our data suggest that the antifungal effect of PQ against Cryptococcus spp. possibly exerts selective pressures interfering with biofilm formation and melanin production by these yeasts.


Subject(s)
Cryptococcus gattii , Cryptococcus neoformans , Herbicides , Antifungal Agents/metabolism , Antifungal Agents/pharmacology , Cryptococcus gattii/metabolism , Cryptococcus neoformans/metabolism , Herbicides/metabolism , Herbicides/pharmacology , Levodopa/metabolism , Levodopa/pharmacology , Melanins/metabolism , Melanins/pharmacology , Microbial Sensitivity Tests , Paraquat/metabolism , Paraquat/pharmacology
4.
J Basic Microbiol ; 61(3): 203-211, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33576034

ABSTRACT

Melanins are a diverse group of dark pigments with similar properties. In fungi, the most studied is the dihydroxynaphtalene (DHN)-melanin, present in several species including all the chromoblastomycosis agents, a chronic, disabling, and recalcitrant subcutaneous mycosis. It is synthesized in a pathway known as the pentaketide pathway, which has the agrochemical tricyclazole as an inhibitor, widely used in in vitro studies because it does not prevent the growth of fungi. There are different methodologies for qualitative and quantitative analyses of DHN-melanin, which made it possible to discover its important structural and antioxidant functions, with melanin acting as a protective factor against the host's immune system. Also, it can interact with some of the main antifungals of medical interest, reducing its activity and the susceptibility of fungi to these agents. This review aims to discuss the aspects of DHN-melanin, focusing on chromoblastomycosis, bringing the main findings of the published scientific studies, and highlighting the need for further research to understand this important fungal pathogenicity and a virulence factor.


Subject(s)
Antifungal Agents/pharmacology , Antioxidants/pharmacology , Ascomycota/drug effects , Chromoblastomycosis/drug therapy , Melanins/pharmacology , Naphthols/pharmacology , Ascomycota/pathogenicity , Humans , Melanins/analysis , Naphthols/analysis
5.
Peptides ; 126: 170249, 2020 04.
Article in English | MEDLINE | ID: mdl-31911169

ABSTRACT

Serotonergic neurons of the median raphe nucleus (MnR) and hypothalamic melanin-concentrating hormone (MCH)-containing neurons, have been involved in the control of REM sleep and mood. In the present study, we examined in rats and cats the anatomical relationship between MCH-containing fibers and MnR neurons, as well as the presence of MCHergic receptors in these neurons. In addition, by means of in vivo unit recording in urethane anesthetized rats, we determined the effects of MCH in MnR neuronal firing. Our results showed that MCH-containing fibers were present in the central and paracentral regions of the MnR. MCHergic fibers were in close apposition to serotonergic and non-serotonergic neurons. By means of an indirect approach, we also analyzed the presence of MCHergic receptors within the MnR. Accordingly, we microinjected MCH conjugated with the fluorophore rhodamine (R-MCH) into the lateral ventricle. R-MCH was internalized into serotonergic and non-serotonergic MnR neurons; some of these neurons were GABAergic. Furthermore, we determined that intracerebroventricular administration of MCH induced a significant decrease in the firing rate of 53 % of MnR neurons, while the juxtacellular administration of MCH reduced the frequency of discharge in 67 % of these neurons. Finally, the juxtacellular administration of the MCH-receptor antagonist ATC-0175 produced an increase in the firing rate in 78 % of MnR neurons. Hence, MCH produces a strong regulation of MnR neuronal activity. We hypothesize that MCHergic modulation of the MnR neuronal activity may be involved in the promotion of REM sleep and in the pathophysiology of depressive disorders.


Subject(s)
Hypothalamic Hormones/pharmacology , Hypothalamus/drug effects , Melanins/pharmacology , Nerve Fibers/drug effects , Neurons/drug effects , Pituitary Hormones/pharmacology , Raphe Nuclei/drug effects , Receptors, Pituitary Hormone/metabolism , Animals , Cats , Hypothalamus/metabolism , Hypothalamus/physiology , Nerve Fibers/metabolism , Nerve Fibers/physiology , Neurons/metabolism , Neurons/physiology , Raphe Nuclei/metabolism , Raphe Nuclei/physiology , Rats , Rats, Wistar
6.
Behav Brain Res ; 374: 112120, 2019 11 18.
Article in English | MEDLINE | ID: mdl-31376444

ABSTRACT

Animal studies have shown that antagonists of receptor 1 of Melanin-Concentrating Hormone (MCH-R1) elicit antidepressive-like behavior, suggesting that MCH-R1 might be a novel target for the treatment of depression and supports the hypothesis that MCHergic signaling regulates depressive-like behaviors. Consistent with the evidence that MCHergic neurons send projections to dorsal and median raphe nuclei, we have previously demonstrated that MCH microinjections in both nuclei induced a depressive-like behavior. Even though MCH neurons also project to Locus Coeruleus (LC), only a few studies have reported the behavioral and neurochemical effect of MCH into the LC. We studied the effects of MCH (100 and 200 ng) into the LC on coping-stress related behaviors associated with depression, using two different behavioral tests: the forced swimming test (FST) and the learned helplessness (LH). To characterize the functional interaction between MCH and the noradrenergic LC system, we also evaluated the neurochemical effects of MCH (100 ng) on the extracellular levels of noradrenaline (NA) in the medial prefrontal cortex (mPFC), an important LC terminal region involved in emotional processing. MCH administration into the LC elicited a depressive-like behavior evidenced in both paradigms. Interestingly, in the LH, MCH (100) elicited a significant increase in escape failures only in stressed animals. A significant decrease in prefrontal levels of NA was observed after MCH microinjection into the LC. Our results demonstrate that increased MCH signaling into the LC triggers depressive-like behaviors, especially in stressed animals. These data further corroborate the important role of MCH in the neurobiology of depression.


Subject(s)
Hypothalamic Hormones/pharmacology , Locus Coeruleus/metabolism , Melanins/pharmacology , Pituitary Hormones/pharmacology , Receptors, Somatostatin/metabolism , Animals , Antidepressive Agents/pharmacology , Depression/chemically induced , Depression/physiopathology , Dorsal Raphe Nucleus/drug effects , Dorsal Raphe Nucleus/metabolism , Emotions/drug effects , Hypothalamic Hormones/metabolism , Locus Coeruleus/drug effects , Male , Melanins/metabolism , Neurons/physiology , Norepinephrine/analysis , Pituitary Hormones/metabolism , Prefrontal Cortex/drug effects , Prefrontal Cortex/metabolism , Rats , Rats, Wistar , Receptors, Somatostatin/antagonists & inhibitors , Stress, Psychological/metabolism , Stress, Psychological/physiopathology
7.
Mem Inst Oswaldo Cruz ; 113(8): e180120, 2018 Jun 25.
Article in English | MEDLINE | ID: mdl-29947713

ABSTRACT

BACKGROUND: Melanin production has been associated with virulence in various pathogenic fungi, including Fonsecaea pedrosoi, the major etiological agent for chromoblastomycosis, a subcutaneous fungal disease that occurs in South America. OBJECTIVE: The aim of this study was to evaluate the effects of acid-basic extracted F. pedrosoi melanin particles and fungal cell ghosts obtained by Novozym 234 treatment on their ability to activate the human complement system. METHODS: The ability of melanin particles and fungal cell ghosts to activate the human complement system was evaluated by complement consumption, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). FINDINGS: Unsensitised melanin particles and melanin ghosts presented complement consumption of 82.67 ± 2.08% and 96.04 ± 1.13%, respectively. Immunofluorescence assays revealed intense deposition of the C3 and C4 fragments on the surface of melanin particles and ghosts extracted from F. pedrosoi. Deposition of the C3, C4, and C5 fragments onto melanin samples and zymosan was confirmed by ELISA. Deposition of small amounts of C1q and C9 onto melanin samples and zymosan was detected by ELISA. CONCLUSION: Fonsecaea pedrosoi melanin particles and fungal cell ghosts activated the complement system mainly through an alternative pathway.


Subject(s)
Ascomycota/chemistry , Complement Activation , Complement System Proteins/immunology , Melanins/pharmacology , Animals , Enzyme-Linked Immunosorbent Assay , Fluorescent Antibody Technique , Humans , Melanins/biosynthesis , Melanins/isolation & purification
8.
Pharm Biol ; 54(6): 1014-21, 2016.
Article in English | MEDLINE | ID: mdl-26459656

ABSTRACT

CONTEXT: A mutant that exhibited increased melanin pigment production was isolated from Aspergillus nidulans fungus. This pigment has aroused biotechnological interest due to its photoprotector and antioxidant properties. In a recent study, we showed that melanin from A. nidulans also inhibits NO and TNF-α production. OBJECTIVE: The present study evaluates the mutagenicity and cytotoxicity of melanin extracted from A. nidulans after its exposure to liver S9 enzymes. MATERIALS AND METHODS: The cytotoxicity of multiple concentrations of melanin (31.2-500 µg/mL) against the McCoy cell line was evaluated using the Neutral Red assay, after incubation for 24 h. Mutagenicity was assessed using the Ames test with the Salmonella typhimurium strains TA98, TA97a, TA100, and TA102 at concentrations ranging from 125 µg/plate to 1 mg/plate after incubation for 48 h. RESULTS: The cytotoxicity of A. nidulans melanin after incubation with S9 enzymes was less than (CI50 value= 413.4 ± 3.1 µg/mL) that of other toxins, such as cyclophosphamide (CI50 value = 15 ± 1.2 µg/mL), suggesting that even the metabolised pigment does not cause significant damage to cellular components at concentrations up to 100 µg/mL. In addition, melanin did not exhibit mutagenic properties against the TA 97a, TA 98, TA 100, or TA 102 strains of S. typhimurium, as shown by a mutagenic index (MI)  <2 in all assays. DISCUSSION AND CONCLUSION: The significance of these results supports the use of melanin as a therapeutic reagent because it possesses low cytotoxicity and mutagenic potential, even when processed through an external metabolising system.


Subject(s)
Aspergillus nidulans/chemistry , Liver , Melanins/metabolism , Melanins/pharmacology , Microsomes, Liver , Animals , Biotransformation , Cell Line , Cell Survival/drug effects , Dose-Response Relationship, Drug , Fibroblasts/drug effects , Fibroblasts/pathology , Liver/drug effects , Liver/enzymology , Melanins/isolation & purification , Mice , Microsomes, Liver/drug effects , Microsomes, Liver/enzymology , Mutagenicity Tests , Rats, Sprague-Dawley , Salmonella typhimurium/drug effects , Salmonella typhimurium/genetics
9.
J Chem Neuroanat ; 72: 16-24, 2016 Mar.
Article in English | MEDLINE | ID: mdl-26686290

ABSTRACT

Melanin-concentrating hormone (MCH)-containing neurons are localized in the lateral hypothalamus and incerto-hypothalamic areas, and project to several brain regions including the dorsal raphe nucleus (DRN). The MCHergic system has been involved in the regulation of emotional states and we have demonstrated that MCH microinjections into the rat DRN promote a depressive-like state. To understand the MCHergic transmission into the DRN, in the present study we characterized the distribution and density of the MCHergic fibers along the rostro-caudal axis of the rat DRN and their anatomical relationship with the 5-HT- and GABA-containing neurons. Additionally, a functional in vivo microdialysis study was carried out in order to evaluate the MCH effects on the 5-HT extracellular levels. Immunolabeling studies showed that MCHergic fibers were widely distributed throughout the rostro-caudal DRN extent and a reduced density at the most caudal level was observed. Interestingly, MCHergic fibers appeared in close apposition to 5-HT and GABA-containing neurons. Microdialysis studies evidenced an opposite effect of two concentrations of MCH on 5-HT levels: the lower concentration (30 µM) produced a significant and long-lasting (up to 120 min) decrease while the higher (100 µM) induced a slight and brief (20 min) increase. Morphological and functional results strongly suggest that both 5-HT- and GABA-containing neurons of the DRN are modulated by MCH. A different sensitivity of these neurons to MCH may explain the dose-response effect on 5-HT release. The decrease in extracellular 5-HT levels may account for the depressive-like effect induced by MCH reported in our previous studies.


Subject(s)
Dorsal Raphe Nucleus/metabolism , GABAergic Neurons/metabolism , Hypothalamic Hormones/metabolism , Melanins/metabolism , Pituitary Hormones/metabolism , Serotonergic Neurons/metabolism , Animals , Dorsal Raphe Nucleus/drug effects , Fluorescent Antibody Technique , Hypothalamic Hormones/pharmacology , Male , Melanins/pharmacology , Microdialysis , Nerve Fibers/metabolism , Pituitary Hormones/pharmacology , Rats, Wistar , Serotonin/metabolism , gamma-Aminobutyric Acid/metabolism
10.
Antimicrob Agents Chemother ; 59(7): 4003-11, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25896704

ABSTRACT

Paracoccidioidomycosis (PCM) is a public health concern in Latin America and South America that when not correctly treated can lead to patient death. In this study, the influence of melanin produced by Paracoccidioides spp. on the effects of treatment with antimicrobial photodynamic inhibition (aPI) and antifungal drugs was evaluated. aPI was performed using toluidine blue (TBO) as a photosensitizer and a 630-nm light-emitting diode (LED) light. The antifungals tested were itraconazole and amphotericin B. We evaluated the effects of each approach, aPI or antifungals, against nonmelanized and melanized yeast cells by performing susceptibility tests and by quantifying oxidative and nitrosative bursts during the experiments. aPI reduced nonmelanized cells by 3.0 log units and melanized cells by 1.3 log units. The results showed that melanization protects the fungal cell, probably by acting as a scavenger of nitric oxide and reactive oxygen species, but not of peroxynitrite. Melanin also increased the MICs of itraconazole and amphotericin B, and the drugs were fungicidal for nonmelanized and fungistatic for melanized yeast cells. Our study shows that melanin production by Paracoccidioides yeast cells serves a protective function during aPI and treatment with itraconazole and amphotericin B. The results suggest that melanin binds to the drugs, changing their antifungal activities, and also acts as a scavenger of reactive oxygen species and nitric oxide, but not of peroxynitrite, indicating that peroxynitrite is the main radical that is responsible for fungal death after aPI.


Subject(s)
Antifungal Agents/pharmacology , Melanins/pharmacology , Paracoccidioides/drug effects , Photochemotherapy , Amphotericin B/chemistry , Amphotericin B/pharmacology , Antifungal Agents/chemistry , Drug Resistance, Fungal/drug effects , Free Radical Scavengers/pharmacology , Itraconazole/chemistry , Itraconazole/pharmacology , Laccase/metabolism , Levodopa/pharmacology , Melanins/chemistry , Microbial Sensitivity Tests , Nitric Oxide/metabolism , Peroxynitrous Acid/metabolism , Reactive Oxygen Species/metabolism , Respiratory Burst/drug effects
11.
Behav Pharmacol ; 25(4): 316-24, 2014 Aug.
Article in English | MEDLINE | ID: mdl-25006977

ABSTRACT

Melanin-concentrating hormone (MCH) administered within the rat dorsal raphe nucleus (DRN) has been shown to elicit prodepressive behaviors in the forced-swim test. The present study was designed to evaluate the time course (30 and 60 min) and dose dependence (25-100 ng) of this effect, and whether it would be antagonized by an intra-DRN microinjection of the MCH-1 receptor antagonist ATC0175 (ATC, 1 mmol/l) or intraperitoneal pretreatment with the noradrenergic antidepressant nortriptyline (20 mg/kg). The results showed that the behavioral effect of MCH was time and dose dependent as immobility was increased, and climbing decreased, only by the 50 ng MCH dose at T30. The effect was mediated by MCH-1 receptors as a significant blockade of this behavioral response was observed in ATC-pretreated animals. ATC did not by itself modify animal behavior. Nortriptyline also prevented the prodepressive-like effect of MCH. Concomitantly, the effect of MCH (50 ng) at T30 on anxiety-related behaviors was assessed using the elevated plus-maze. Interestingly, these behaviors were unchanged. In conclusion, MCH administration within the DRN elicits, through the MCH-1 receptor, a depression-related behavior that is not accompanied by changes in anxiety and that is prevented by a noradrenergic antidepressant.


Subject(s)
Central Nervous System Depressants/pharmacology , Depression/chemically induced , Dorsal Raphe Nucleus/drug effects , Hypothalamic Hormones/pharmacology , Melanins/pharmacology , Pituitary Hormones/pharmacology , Animals , Antidepressive Agents/pharmacology , Antidepressive Agents, Tricyclic/pharmacology , Anxiety/chemically induced , Anxiety/physiopathology , Behavior, Animal/drug effects , Behavior, Animal/physiology , Central Nervous System Depressants/antagonists & inhibitors , Cyclohexylamines/pharmacology , Depression/physiopathology , Dorsal Raphe Nucleus/physiopathology , Dose-Response Relationship, Drug , Hypothalamic Hormones/antagonists & inhibitors , Male , Maze Learning/drug effects , Maze Learning/physiology , Melanins/antagonists & inhibitors , Microinjections , Motor Activity/drug effects , Motor Activity/physiology , Neuropsychological Tests , Nortriptyline/pharmacology , Pituitary Hormones/antagonists & inhibitors , Quinazolines/pharmacology , Rats, Wistar , Receptors, Somatostatin/metabolism , Time Factors
12.
Peptides ; 58: 20-5, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24893251

ABSTRACT

Melanin-concentrating hormone (MCH) is an inhibitory neuropeptide mainly synthesized in neurons of the lateral hypothalamus and incerto-hypothalamic area of mammals that has been implicated in behavioral functions related to motivation. During lactation, this neuropeptide is also expressed in the medial preoptic area (mPOA), a key region of the maternal behavior circuitry. Notably, whereas MCH expression in the mPOA progressively increases during lactation, maternal behavior naturally declines, suggesting that elevated MCHergic activity in the mPOA inhibit maternal behavior in the late postpartum period. To explore this idea, we assessed the maternal behavior of early postpartum females following bilateral microinfusions of either MCH (50 and 100 ng/0.2 µl/side) or the same volume of vehicle into the mPOA. As expected, females receiving 100 ng MCH into the mPOA exhibited significant deficits in the active components of maternal behavior, including retrieving and nest building. In contrast, nursing, as well as other behaviors, including locomotor activity, exploration, and anxiety-like behavior, were not affected by intra-mPOA MCH infusion. The present results, together with previous findings showing elevated expression of this neuropeptide toward the end of the postpartum period, suggest that modulation of mPOA function by MCH may contribute to the weaning of maternal responsiveness characteristic of the late postpartum period.


Subject(s)
Behavior, Animal/drug effects , Hypothalamic Hormones/pharmacology , Maternal Behavior/drug effects , Melanins/pharmacology , Pituitary Hormones/pharmacology , Preoptic Area , Animals , Female , Lactation/drug effects , Rats , Rats, Wistar
13.
Rev Chilena Infectol ; 31(1): 28-33, 2014 Feb.
Article in Spanish | MEDLINE | ID: mdl-24740771

ABSTRACT

BACKGROUND: Melanocytes are cells located in epidermis and mucous membranes that synthesize melanin and cytokines. It is known that melanin has antimicrobial activity and that melanocytes are melanized in presence of microbial molecules. OBJECTIVE: To study the antifungal activity of melanin on Candida spp. METHODOLOGY: The minimum inhibitory concentration (MIC) to melanin was determined in 4 Candida ATCC strains (C. albicans SC5314, C. parapsilosis 22019, C. glabrata 2001, C. krusei 6258) and 56 clinical isolates of Candida spp. (33 C. albicans, 12 C. glabrata, 3 C. famata, 3 C. krusei, 3 C. parapsilosis, 2 C. tropicalis) using a broth microdilution method. In addition, the antifungal activity of melanocytes and mice melanoma cells was tested against C. albicans. RESULTS: Melanin inhibited the tested isolates, including the susceptible dose-dependent and fluconazole-resistant strains; MIC range and MIC50 were 0.09-50 µg/mL and 6.25 µg/mL, respectively. Pigmented cells lysates inhibited C. albicans. CONCLUSIONS: Melanin is able to inhibit clinical isolates of Candida spp. Melanization could be an important protective mechanism of melanocytes.


Subject(s)
Antifungal Agents/pharmacology , Candida albicans/drug effects , Fluconazole/pharmacology , Melanins/pharmacology , Melanocytes/immunology , Animals , Candida albicans/classification , Candida albicans/growth & development , Drug Resistance, Fungal , Melanins/metabolism , Melanocytes/metabolism , Melanoma, Experimental/metabolism , Melanoma, Experimental/microbiology , Mice , Skin Pigmentation
14.
Rev. chil. infectol ; Rev. chil. infectol;31(1): 28-33, feb. 2014. ilus, graf, tab
Article in Spanish | LILACS | ID: lil-706543

ABSTRACT

Background: Melanocytes are cells located in epidermis and mucous membranes that synthesize melanin and cytokines. It is known that melanin has antimicrobial activity and that melanocytes are melanized in presence of microbial molecules. Objective: To study the antifungal activity of melanin on Candida spp. Methodology: The minimum inhibitory concentration (MIC) to melanin was determined in 4 Candida ATCC strains (C. albicans SC5314, C. parapsilosis 22019, C. glabrata 2001, C. krusei 6258) and 56 clinical isolates of Candida spp. (33 C. albicans, 12 C. glabrata, 3 C. famata, 3 C. krusei, 3 C. parapsilosis, 2 C. tropicalis) using a broth microdilution method. In addition, the antifungal activity of melanocytes and mice melanoma cells was tested against C. albicans. Results: Melanin inhibited the tested isolates, including the susceptible dose-dependent and fluconazole-resistant strains; MIC range and MIC50 were 0.09-50 μg/mL and 6.25 μg/mL, respectively. Pigmented cells lysates inhibited C. albicans. Conclusions: Melanin is able to inhibit clinical isolates of Candida spp. Melanization could be an important protective mechanism of melanocytes.


Introducción: Los melanocitos son células presentes en piel y en mucosas que sintetizan melanina, además de citoquinas. Es sabido que melanina presenta actividad antimicrobiana y que los melanocitos se melanizan al ser expuestos a moléculas microbianas. Objetivo: Estudiar la actividad antifúngica de melanina en cepas clínicas de Candida spp. Metodología: Se midió la concentración inhibitoria mínima (CIM) a melanina, de 4 cepas de Candida ATCC (C. albicans SC5314, C. parapsilosis 22019, C. glabrata 2001 y C. krusei 6258) y 56 aislados clínicos de Candida spp. (33 C. albicans, 12 C. glabrata, 3 C. famata, 3 C. krusei, 3 C. parapsilosis, 2 C. tropicalis) mediante un método de microdilución en caldo. Además se estudió el efecto antifúngico de lisados de melanocitos y células de melanoma de ratón en C. albicans. Resultados: Melanina inhibió las cepas analizadas, incluso cepas susceptibles dosis-dependiente y resistentes a fluconazol, siendo los rangos de CIM y CIM50 de 0,09-50 μg/mL y 6,25 μg/ mL, respectivamente. Los lisados de células pigmentadas inhibieron C. albicans. Conclusiones: Melanina es capaz de inhibir cepas clínicas de Candida spp. La melanización podría ser un importante mecanismo protector de los melanocitos.


Subject(s)
Animals , Mice , Antifungal Agents/pharmacology , Candida albicans/drug effects , Fluconazole/pharmacology , Melanins/pharmacology , Melanocytes/immunology , Candida albicans/classification , Candida albicans/growth & development , Drug Resistance, Fungal , Melanins/metabolism , Melanocytes/metabolism , Melanoma, Experimental/metabolism , Melanoma, Experimental/microbiology , Skin Pigmentation
15.
Brain Res ; 1491: 68-77, 2013 Jan 23.
Article in English | MEDLINE | ID: mdl-23122879

ABSTRACT

Within the postero-lateral hypothalamus neurons that utilize hypocretin or melanin-concentrating hormone (MCH) as neuromodulators are co-distributed. These neurons have been involved in the control of behavioral states, and a deficit in the hypocretinergic system is the pathogenic basis of narcolepsy with cataplexy. In this report, utilizing immunohistochemistry and retrograde tracing techniques, we examined the hypocretinergic innervation of the nucleus pontis oralis (NPO), which is the executive site that is responsible for the generation of REM sleep in the cat. The retrograde tracer cholera toxin subunit b (CTb) was administered in pontine regions where carbachol microinjections induced REM sleep. Utilizing immunohistochemical techniques, we found that approximately 1% of hypocretinergic neurons in the tuberal area of the hypothalamus project to the NPO. In addition, approximately 6% of all CTb+ neurons in this region were hypocretinergic. The hypocretinergic innervation of the NPO was also compared with the innervation of the same site by MCH-containing neurons. More than three times as many MCHergic neurons were found to project to the NPO compared with hypocretinergic cells; both neuronal types exhibited bilateral projections. We also identified a group of non-hypocretinergic non-MCHergic neuronal group of neurons that were intermingled with both hypocretinergic and MCHergic neurons that also projected to this same brainstem region. These neurons were grater in number that either hypocretin or MCH-containing neurons; their soma size was also smaller and their projections were mainly ipsilateral. The present anatomical data suggest that hypocretinergic, MCHergic and an unidentified companion group of neurons of the postero-lateral hypothalamus participate in the regulation of the neuronal activity of NPO neurons, and therefore, are likely to participate in the control of wakefulness and REM sleep.


Subject(s)
Hypothalamus/physiology , Intracellular Signaling Peptides and Proteins/physiology , Neural Pathways/physiology , Neuropeptides/physiology , Pons/physiology , Sleep, REM/physiology , Animals , Carbachol/pharmacology , Cats , Cholera Toxin , Hypothalamic Hormones/pharmacology , Immunohistochemistry , Male , Melanins/pharmacology , Microinjections , Neural Pathways/drug effects , Orexins , Pituitary Hormones/pharmacology , Polysomnography , Sleep, REM/drug effects
16.
Life Sci ; 90(23-24): 895-9, 2012 Jun 14.
Article in English | MEDLINE | ID: mdl-22579511

ABSTRACT

AIMS: To examine the effects of bilateral microinjection of melanin-concentrating hormone (MCH) 50 and 100 ng into the horizontal limb of the diagonal band of Broca (HDB) on sleep variables during the light phase of the light-dark cycle of the rat. MAIN METHODS: Male Wistar rats were implanted for chronic sleep recordings. In addition, a guide cannula was implanted above the right and left HDB. Following the microinjection of MCH or control solution the electroencephalogram and the electromyogram were recorded for 6 h. Data was collected and classified as either wakefulness (W), light sleep, slow wave sleep (SWS) or REM sleep (REMS). Latencies for SWS and REMS, as well as the number of REM periods and the mean duration of REM episodes were also determined. KEY FINDINGS: MCH 50 and 100 ng significantly decreased W during the first 2-h of recording. Moreover, MCH 100 ng significantly reduced REMS latency and increased REMS time during the first 2-h block of the recording, due to an increase in the number of REM periods. SIGNIFICANCE: Our findings tend to suggest that the basal forebrain participates in the effects of MCH on W and REMS through the deactivation of cholinergic, glutamatergic and γ-aminobutyric acid (GABA)-ergic cells.


Subject(s)
Hypothalamic Hormones/pharmacology , Melanins/pharmacology , Pituitary Hormones/pharmacology , Prosencephalon/metabolism , Sleep, REM/drug effects , Wakefulness/drug effects , Acetylcholine/metabolism , Animals , Dose-Response Relationship, Drug , Electroencephalography , Electromyography , Glutamic Acid/metabolism , Hypothalamic Hormones/administration & dosage , Male , Melanins/administration & dosage , Microinjections , Pituitary Hormones/administration & dosage , Rats , Rats, Wistar , gamma-Aminobutyric Acid/metabolism
17.
Brain Res ; 1369: 112-8, 2011 Jan 19.
Article in English | MEDLINE | ID: mdl-21078307

ABSTRACT

Hypothalamic neurons that utilize melanin-concentrating hormone (MCH) as a neuromodulator exert a positive control over energy homeostasis, inducing feeding and decreasing metabolism. Recent studies have shown also that this system plays a role in the generation and/or maintenance of sleep. MCHergic neurons project to the serotonergic dorsal raphe nucleus (DR), a neuroanatomical structure involved in several functions during wakefulness (W), and in the regulation of rapid-eye movements (REM) sleep. Recently, we determined the effect of MCH microinjected into the DR on sleep variables in the rat. MCH produced a marked increment of REM sleep, whereas slow wave sleep (SWS) showed only a moderate increase. In the present study, we analyze the effect of immunoneutralization of MCH in the DR on sleep and W in the rat. Compared to the control solution, microinjections of anti-MCH antibodies (1/100 solution in 0.2 µl) induced a significant increase in REM sleep latency (31.2±7.1 vs. 84.2±24.8 min, p<0.05) and a decrease of REM sleep time (37.8±5.4 vs. 17.8±2.9 min, p<0.05) that was related to the reduction in the number of REM sleep episodes. In addition, there was an increase of total W time (49.8±4.6 vs. 72.0±5.7 min, p<0.01). Light sleep and SWS remained unchanged. The intra-DR administration of a more diluted solution of anti-MCH antibodies (1/500) or rabbit pre-immune serum did not modify neither W nor REM sleep variables. Our findings strongly suggest that MCH released in the DR facilitates the occurrence of REM sleep.


Subject(s)
Hypothalamic Hormones/metabolism , Melanins/metabolism , Pituitary Hormones/metabolism , Raphe Nuclei/metabolism , Sleep, REM/physiology , Wakefulness/physiology , Animals , Hypothalamic Hormones/pharmacology , Male , Melanins/pharmacology , Microinjections , Pituitary Hormones/pharmacology , Raphe Nuclei/drug effects , Rats , Rats, Wistar , Sleep/physiology
18.
J Colloid Interface Sci ; 350(1): 268-74, 2010 Oct 01.
Article in English | MEDLINE | ID: mdl-20633887

ABSTRACT

The use of melanin in bioinspired applications is mostly limited by its poor stability in solid films. This problem has been addressed here by incorporating melanin into dipalmitoyl phosphatidyl glycerol (DPPG) liposomes, which were then immobilized onto a solid substrate as an LbL film. Results from steady-state and time-resolved fluorescence indicated an increased stability for melanin incorporated into DPPG liposomes. If not protected by liposomes, melanin looses completely its fluorescence properties in LbL films. The thickness of the liposome-melanin layer obtained from neutron reflectivity data was 4.1+/-0.2 nm, consistent with the value estimated for the phospholipid bilayer of the liposomes, an evidence of the collapse of most liposomes. On the other hand, the final roughness indicated that some of the liposomes had their structure preserved. In summary, liposomes were proven excellent for encapsulation, thus providing a suitable environment, closer to the physiological conditions without using organic solvents or high pHs.


Subject(s)
Liposomes/chemistry , Melanins/pharmacology , Phosphatidylglycerols/chemistry , Drug Stability , Imines/chemistry , Polyamines/chemistry , Polyethylenes/chemistry , Spectroscopy, Fourier Transform Infrared , Surface Properties
19.
Brain Res ; 1265: 103-10, 2009 Apr 10.
Article in English | MEDLINE | ID: mdl-19230831

ABSTRACT

Neurons that utilize melanin-concentrating hormone (MCH) as a neuromodulator are located in the lateral hypothalamus and incerto-hypothalamic area, and project diffusely throughout the central nervous system, including areas that participate in the generation and maintenance of the states of sleep and wakefulness. Recent studies have shown that the hypothalamic MCHergic neurons are active during rapid eye movements (REM) sleep, and that intraventricular microinjections of MCH induce slow wave sleep (SWS) and REM sleep. There are particular dense MCHergic projections to the dorsal raphe nucleus (DR), a neuroanatomical structure involved in several functions during wakefulness, and in the regulation of sleep variables. Because of this fact, we analyzed the effect of microinjections of MCH into this nucleus on sleep and waking states in the rat. Compared to control microinjections, MCH (100 ng) produced a moderate increase in SWS (243.7+/-6.0 vs. 223.2+/-8.8 min, p<0.05) and an important increment in REM sleep (35.5+/-2.5 vs. 20.8+/-3.4 min, p<0.01) due to an increase in the number of REM sleep episodes. The increase of REM sleep was accompanied by a reduction in the time spent in light sleep and wakefulness. We therefore conclude that the hypothalamic MCHergic system, via its action in the DR, plays an important role in the generation and/or maintenance of the states of sleep.


Subject(s)
Hypothalamic Hormones/pharmacology , Melanins/pharmacology , Pituitary Hormones/pharmacology , Raphe Nuclei/drug effects , Sleep, REM/drug effects , Sleep/drug effects , Wakefulness/drug effects , Animals , Electroencephalography , Hypothalamic Hormones/administration & dosage , Male , Melanins/administration & dosage , Microinjections , Pituitary Hormones/administration & dosage , Rats , Rats, Wistar
20.
Cell Tissue Res ; 333(1): 49-59, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18506486

ABSTRACT

We detected a close morphological association between melanin-concentrating hormone (MCH)-immunoreactive (ir) fibers and somatolactin (SL)-ir cells in the pars intermedia of the cichlid fish Cichlasoma dimerus by double-label immunofluorescence. Male pituitaries obtained from adult C. dimerus were incubated with 0.1-10 microM salmon MCH, and the amount of SL released into the culture medium was semi-quantified by Western blot. This assay showed an increase of SL release in a dose-dependent manner (linear regression: P<0.05). A close association of GnRH-ir fibers with SL-ir cells was also detected at the pars intermedia level. Male pituitaries were also incubated with 0.1-10 microM of mammalian GnRH, and SL release was semi-quantified by Western blot, showing an increase of released SL levels in a dose-dependent manner (linear regression: P<0.05). In contrast, SL release was unaffected from female pituitaries incubated with salmon MCH; however, an increasing tendency was observed when mammalian GnRH was used. Hypothalamic close association of MCH-ir perikarya and GnRH-ir fibers was found by double-label immunofluorescence indicating a possible relationship between them. These results suggest that SL, like other pituitary hormones, is under hypothalamic control and is involved in diverse physiological processes including background adaptation and reproduction. This study has also shown that the in vitro culture of a single C. dimerus pituitary is a feasible method for studying the control of SL release and other pituitary hormones.


Subject(s)
Cichlids/physiology , Fish Proteins/metabolism , Gonadotropin-Releasing Hormone/pharmacology , Growth Hormone/metabolism , Hypothalamic Hormones/pharmacology , Melanins/pharmacology , Pituitary Hormones/pharmacology , Animals , Cells, Cultured , Culture Media/chemistry , Dose-Response Relationship, Drug , Feasibility Studies , Female , Growth Hormone/chemistry , Kinetics , Male , Molecular Weight , Pituitary Gland/cytology , Protein Isoforms , Reproducibility of Results , Salmon , Time Factors
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