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Expression of Circadian Clock and Melatonin Receptors within Cultured Rat Cardiomyocytes

PELICIARI-GARCIA, Rodrigo A.; ZANQUETTA, Melissa M.; ANDRADE-SILVA, Jessica; GOMES, Dayane A.; BARRETO-CHAVES, Maria Luiza; CIPOLLA-NETO, Jose
Fonte: INFORMA HEALTHCARE Publicador: INFORMA HEALTHCARE
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.41%
Melatonin, the pineal gland hormone, provides entrainment of many circadian rhythms to the ambient light/dark cycle. Recently, cardiovascular studies have demostrated melatonin interactions with many physiological processes and diseases, such as hypertension and cardiopathologies. Although membrane melatonin receptors (MT1, MT2) and the transcriptional factor ROR alpha have been reported to be expressed in the heart, there is no evidence of the cell-type expressing receptors as well as the possible role of melatonin on the expression of the circadian clock of cardiomyocytes, which play an important role in cardiac metabolism and function. Therefore, the aim of this study was to evaluate the mRNA and protein expressions of MT1, MT2, and ROR alpha and to determine whether melatonin directly influences expression of circadian clocks within cultured rat cardiomyocytes. Adult rat cardiomyocyte cultures were created, and the cells were stimulated with 1 nM melatonin or vehicle. Gene expressions were assayed by real-time polymerase chain reaction (PCR). The mRNA and protein expressions of membrane melatonin receptors and RORa were established within adult rat cardiomyocytes. Two hours of melatonin stimulation did not alter the expression pattern of the analyzed genes. However...

Melatonin triggers PKA activation in the rodent malaria parasite Plasmodium chabaudi

GAZARINI, Marcos L.; BERALDO, Flavio H.; ALMEIDA, Fabiana M.; BOOTMAN, Martin; SILVA, Aline M. da; GARCIA, Celia R. S.
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.37%
Calcium (Ca2+) is a critical regulator of many aspects of the Plasmodium reproductive cycle. In particular, intra-erythrocyte Plasmodium parasites respond to circulating levels of the melatonin in a process mediated partly by intracellular Ca2+. Melatonin promotes the development and synchronicity of parasites, thereby enhancing their spread and worsening the clinical implications. The signalling mechanisms underlying the effects of melatonin are not fully established, although both Ca2+ and cyclic AMP (cAMP) have been implicated. Furthermore, it is not clear whether different strains of Plasmodium use the same, or divergent, signals to control their development. The aim of this study was to explore the signalling mechanisms engaged by melatonin in P. chabaudi, a virulent rodent parasite. Using parasites at the throphozoite stage acutely isolated from mice erythrocytes, we demonstrate that melatonin triggers cAMP production and protein kinase A (PKA) activation. Interestingly, the stimulation of cAMP/PKA signalling by melatonin was dependent on elevation of Ca2+ within the parasite, because buffering Ca2+ changes using the chelator BAPTA prevented cAMP production in response to melatonin. Incubation with melatonin evoked robust Ca2+ signals within the parasite...

Developmental and light-entrained expression of melatonin and its relationship to the circadian clock in the sea anemone Nematostella vectensis

Peres, Rafael; Reitzel, Adam M; Passamaneck, Yale; Afeche, Solange Castro; Neto, Jose Cipolla; Marques, Antonio Carlos; Martindale, Mark Q.
Fonte: BioMed Central; London Publicador: BioMed Central; London
Tipo: Artigo de Revista Científica
ENG
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37.37%
Background The primary hormone of the vertebrate pineal gland, melatonin, has been identified broadly throughout the eukaryotes. While the role for melatonin in cyclic behavior via interactions with the circadian clock has only been reported in vertebrates, comparative research has shown that the transcription-translation loops of the animal circadian clock likely date to the cnidarian-bilaterian ancestor, leaving open significant questions about the evolutionary origin of melatonin signaling in circadian behavior by interacting with the molecular clock. Results Expression of melatonin in adult anemones showed peak expression at the end of light period (zeitgeber time (ZT) = 12) when cultured under diel conditions, coinciding with expression of genes and enzyme activity for members of the melatonin synthesis pathway (tryptophan hydroxylase and hydroxyindol-O-methyltransferase), which also showed rhythmic expression. During embryogenesis and juvenile stages, melatonin showed cyclic oscillations in concentration, peaking in midday. Spatial (in situ hybridization) and quantitative (real-time PCR) transcription of clock genes during development of N. vectensis showed these ‘clock’ genes are expressed early in the development...

Developmental and light-entrained expression of melatonin and its relationship to the circadian clock in the sea anemone Nematostella vectensis

Peres, Rafael; Reitzel, Adam M; Passamaneck, Yale; Afeche, Solange Castro; Neto, Jose Cipolla; Marques, Antonio Carlos; Martindale, Mark Q
Fonte: London Publicador: London
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.37%
Background: The primary hormone of the vertebrate pineal gland, melatonin, has been identified broadly throughout the eukaryotes. While the role for melatonin in cyclic behavior via interactions with the circadian clock has only been reported in vertebrates, comparative research has shown that the transcription-translation loops of the animal circadian clock likely date to the cnidarian-bilaterian ancestor, leaving open significant questions about the evolutionary origin of melatonin signaling in circadian behavior by interacting with the molecular clock. Results: Expression of melatonin in adult anemones showed peak expression at the end of light period (zeitgeber time (ZT) = 12) when cultured under diel conditions, coinciding with expression of genes and enzyme activity for members of the melatonin synthesis pathway (tryptophan hydroxylase and hydroxyindol-O-methyltransferase), which also showed rhythmic expression. During embryogenesis and juvenile stages, melatonin showed cyclic oscillations in concentration, peaking in midday. Spatial (in situ hybridization) and quantitative (real-time PCR) transcription of clock genes during development of N. vectensis showed these ‘clock’ genes are expressed early in the development, prior to rhythmic oscillations...

Vias de transdução envolvidas na síntese de melatonina por fagócitos do colostro humano; Transduction pathways involved in melatonin synthesis by human colostral phagocytes

Lapa, Marco Antonio Pires Camilo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/09/2010 PT
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A síntese de melatonina por fagócitos mononucleares do colostro humano é iniciada após a indução com a partícula zimosan, com ou sem opsonização por IgA. Esta produção é dependente da ativação da via NFKB, o que foi observado após o bloqueio farmacológico da via com PDTC ou ALLN levando a diminuição da concentração de melatonina nas culturas. A localização do NFKB varia temporalmente após o estímulo inicial e as subunidades do NFKB são diferentes no núcleo de células ativadas. A subunidade p50 está presente em todas as condições experimentais (controle, zimosan e zimosan opsonizado), mas as subunidades Rel A e c-Rel apenas nas células tratadas. A melatonina apresenta atividade sobre células imunocompetentes em diversos modelos experimentais, mas o modelo de fagocitose ainda não havia sido relatado na literatura. Observamos que a melatonina é capaz de potenciar a fagocitose de zimosan não opsonizado. A capacidade de síntese de melatonina apresentada por células imunocompetentes é um fenômeno conhecido e agora pudemos demonstrar que a via NFKB é responsável também pela síntese de melatonina em fagócitos mononucleares do colostro. Ao contrário do que ocorre na glândula pineal onde a ativação da via do NFKB bloqueia a síntese de melatonina...

O tratamento com melatonina, associado ou não à pioglitazona, melhora a resposta metabólica do tecido adiposo em ratos diabéticos.; Melatonin treatment and its association with pioglitazone improves metabolic response in subcutaneous, periepididymal and retroperitoneal adipose tissue in diabetic rats.

Oliveira, Ariclecio Cunha de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 30/05/2012 PT
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37.4%
Diabetes mellitus é uma doença resultante da baixa sensibilidade à insulina ou insuficiência da célula beta pancreática ou da associação dos dois fatores. Ratos com diabetes induzida por estreptozotocina durante o período neonatal no quinto dia de idade desenvolvem o quadro diabético clássico de hiperglicemia, hipoinsulinemia, poliúria, polidipsia agravada pela resistência à insulina na vida adulta. Neste estudo, foi investigado se o efeito de longo prazo do tratamento com melatonina e a sua associação com a pioglitazona pode melhorar a resistência à insulina e outras desordens metabólicas nesses animais. Após o desmame, os animais foram divididos nos seguintes grupos: grupo controle (C) - animais saudáveis controle; grupo diabético (D) - animais diabéticos sem tratamento adicional; grupo melatonina (M) - ratos diabéticos tratados com melatonina (1mg/kg); grupo melatonina mais pioglitazona (MP) - ratos diabéticos tratados com melatonina (1mg/kg) e pioglitazona (5mg/kg). Quando adultos (12ª semana de idade) animais foram sacrificados e os tecidos adiposos subcutâneos (SC), epididimal (EP) e retroperitoneal (RP) foram retirados, pesados e processados para isolamento dos adipócitos para avaliar a taxa de captação de glicose...

Desenvolvimento tecnológico e avaliação da atividade antioxidante de sistemas nano e microparticulados contendo melatonina; Technological development and evaluation of the antioxidant activity of melatonin-loaded nano- and microparticulated systems

Schaffazick, Scheila Rezende
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
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37.43%
Este trabalho centrou-se no desenvolvimento tecnológico e na caracterização de nanopartículas poliméricas (nanocápsulas ou nanoesferas) contendo melatonina, empregando diferentes composições, métodos de preparação e concentrações de melatonina. De uma maneira geral, as diferentes suspensões nanoparticuladas foram caracterizadas segundo a determinação dos teores totais de melatonina, a determinação das taxas de associação da melatonina aos nanocarreadores, a análise morfológica, a determinação dos diâmetros médios de partículas e polidispersões, além da determinação dos valores de potenciais zeta. As suspensões de nanocápsulas ou de nanoesferas foram preparadas pelos métodos de deposição interfacial ou de nanoprecipitação, respectivamente. Foram avaliadas as influências do tipo de polímero [Eudragit® S100, Eudragit® RS100, poli(ε-caprolactona) ou poli(lactideo)], de óleo (triglicerídeos dos ácidos cáprico e caprílico, óleo mineral ou Eutanol G®) e de tensoativos (polissorbato 80, poloxamer 188, monooleato de sorbitano, monoestearato de sorbitano ou lecitina) sobre as características físico-químicas das suspensões. Os resultados demonstraram que as nanopartículas apresentaram diâmetros inferiores a 350 nm...

Antioxidant Effect of Melatonin on the Functional Activity of Colostral Phagocytes in Diabetic Women

Morceli, Gliciane; Honorio-França, Adenilda C.; Fagundes, Danny L. G.; Calderon, Iracema de Mattos Paranhos; França, Eduardo L.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
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37.41%
Melatonin is involved in a number of physiological and oxidative processes, including functional regulation in human milk. The present study investigated the mechanisms of action of melatonin and its effects on the functional activity of colostral phagocytes in diabetic women. Colostrum samples were collected from normoglycemic (N = 38) and diabetic (N = 38) women. We determined melatonin concentration, superoxide release, bactericidal activity and intracellular Ca2+ release by colostral phagocytes treated or not with 8-(Diethylamino) octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8) and incubated with melatonin and its precursor (N-acetyl-serotonin-NAS), antagonist (luzindole) and agonist (chloromelatonin-CMLT). Melatonin concentration was higher in colostrum samples from hyperglycemic than normoglycemic mothers. Melatonin stimulated superoxide release by colostral phagocytes from normoglycemic but not hyperglycemic women. NAS increased superoxide, irrespective of glycemic status, whereas CMTL increased superoxide only in cells from the normoglycemic group. Phagocytic activity in colostrum increased significantly in the presence of melatonin, NAS and CMLT, irrespective of glycemic status. The bactericidal activity of colostral phagocytes against enterophatogenic Escherichia coli (EPEC) increased in the presence of melatonin or NAS in the normoglycemic group...

Melatonin and ethanol intake exert opposite effects on circulating estradiol and progesterone and differentially regulate sex steroid receptors in the ovaries, oviducts, and uteri of adult rats

Chuffa, Luiz Gustavo A.; Seiva, Fábio R.F.; Fávaro, Wagner José; Amorim, João Paulo A.; Teixeira, Giovana R.; Mendes, Leonardo O.; Fioruci-Fontanelli, Beatriz A.; Pinheiro, Patricia Fernanda F.; Martinez, Marcelo; Martinez, Francisco Eduardo
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 40-49
ENG
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37.38%
Chronic ethanol intake is associated with sex hormone disturbances, and it is well known that melatonin plays a key role in regulating several reproductive processes. We report the effects of ethanol intake and melatonin treatment (at doses of 100. μg/100. g. BW/day) on sex hormones and steroid receptors in the ovaries, oviducts and uteri of ethanol-preferring rats. After 150 days of treatment, animals were euthanized, and tissue samples were harvested to evaluate androgen, estrogen, progesterone and melatonin receptor subunits (AR, ER-α and ER-β, PRA, PRB and MT1R, respectively). Melatonin decreased estradiol (E2) and increased progesterone (P4) and 6-sulfatoxymelatonin (6-STM), while an ethanol-melatonin combination reduced both P4 and E2. Ovarian AR was not influenced by either treatment, and oviduct AR was reduced after ethanol-melatonin combination. Oviduct ER-α, ER-β and uterine ER-β were down-regulated by either ethanol or melatonin. Conversely, ovarian PRA and PRB were positively regulated by ethanol and ethanol-melatonin combination, whereas PRA was down-regulated in the uterus and oviduct after ethanol consumption. MT1R was increased in ovaries and uteri of melatonin-treated rats. Ethanol and melatonin exert opposite effects on E2 and P4...

Ação da melatonina sobre os receptores esteróides sexuais no ovário, oviduto e útero e o estresse oxidativo nos ovários de ratas adultas UChB (consumidoras voluntárias de etanol a 10%) durante a ovulação; Effects of exogenous melatonin on sex steroid receptors in the ovary, oviduct and uterus and the ovarian oxidative stress in adult UChB rats (10% (v/v) ethanol voluntary intake) during ovulation

Luiz Gustavo de Almeida Chuffa
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/10/2011 PT
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37.46%
O alcoolismo crônico está associado a distúrbios no sistema reprodutor feminino como disfunção hormonal, alteração na expressão dos receptores esteróides, produção de espécies reativas de oxigênio (ERO), entre outros. A melatonina, hormônio secretado pela glândula pineal, possui função moduladora no ciclo reprodutivo e têm papel importante no combate as ERO. Os estudos envolvendo o alcoolismo crônico e sua interação com a melatonina, em fêmeas, são ainda inconclusivos. O presente trabalho tem como objetivo investigar os efeitos da administração exógena da melatonina sobre os hormônios sexuais, os receptores esteróides sexuais (AR, ER-?, ER-?, PRA e PRB) no ovário, oviduto e útero, além do perfil nutricional e o estresse oxidativo nos ovários de ratas adultas UChB (consumidoras voluntárias de etanol a 10%). Foram utilizadas 60 ratas UChB, distribuídas nos seguintes grupos: UChB Co: sem acesso ao etanol; UChB EtOH: consumo diário de 4 - 5 g etanol/100g de peso corpóreo (PC), ambos recebendo solução veículo. Concomitantemente, os grupos UChB Co+M e UChB EtOH+M receberam injeções diárias de melatonina (100?g/100g PC) via i.p, a partir dos 90 dias de idade, durante 60 dias consecutivos. Aos 150 dias de idade...

Baixas doses de melatonina exógena no diabetes experimental : implicações para a estrutura, função e defesa antioxidante do testículo e epidídimo de ratos = Low doses of exogen melatonin under experimental diabetes: implications for rat testicular and epididimal structure, function and antioxidant defense; Low doses of exogen melatonin under experimental diabetes : implications for rat testicular and epididimal structure, function and antioxidant defense

Carolina Frandsen Pereira da Costa
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 31/07/2014 PT
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37.44%
Existem inúmeras evidências de que o diabetes afeta a função reprodutiva masculina, provocando danos aos parâmetros espermáticos, e portanto, influenciando a fertilidade dos indivíduos afetados. A melatonina é um hormônio secretado pela glândula pineal que apresenta uma extensa gama de atuações, dentre elas um papel fundamental no controle da esteroidogênese e na proteção contra radicais livres. O objetivo deste estudo foi avaliar se a melatonina oferecida oralmente, em baixas doses, concomitante à maturação sexual, afeta os parâmetros reprodutivos de ratos saudáveis na idade adulta, e se interfere nos danos reprodutivos induzidos pelo diabetes experimental. Ratos Wistar machos com 4 semanas de idade foram divididos em oito grupos (n=15/grupo): os quatro primeiros foram eutanaziados com 14 semanas de idade, sendo respectivamente - controle (CS), tratados com melatonina (MS), diabéticos (DS) e tratados com melatonina submetidos ao diabetes (MDS); por sua vez, os quatro últimos foram eutanasiados na 21ª semana de vida- controle (CL), tratados com melatonina (ML), diabéticos não tratados (DL) e diabéticos tratados com melatonina (MDL). A melatonina foi disponibilizada na água de beber (10 µg/Kg p.c. em 0,001% etanol/dia) diariamente à partir da 5ª semana de idade...

Effect of melatonin in the antioxidant defense system in the locomotor muscles of the estuarine crab Neohelice granulata (Decapoda, Brachyura)

Geihs, Marcio Alberto; Vargas, Marcelo Alves; Maciel, Fabio Everton; Caldas, Sergiane Souza; Cruz, Bruno Pinto; Primel, Ednei Gilberto; Monserrat, José María; Nery, Luiz Eduardo Maia
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.38%
In vertebrates, many studies verified different effects of melatonin in the antioxidant defense system (ADS). In crustaceans, few studies have been conducted to verify this possibility. We verified the melatonin effects in the crab Neohelice granulata using low (0.002 and 0.02 pmol/crab) and high (2.0 and 20.0 pmol/crab) melatonin dosages in short-term (0.5 h) and long-term (9.5 h) experiments. We analyzed the antioxidant capacity against peroxyl radicals (ACAP), reactive oxygen species (ROS) concentration, levels of by products of lipid peroxidation (LPO), oxygen consumption (VO2), the activity of glutamate cysteine ligase (c-GCL) and catalase (CAT) and glutathione content (GSH). Finally, the effects of exogenous melatonin were verified in terms of melatonin and N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) content in the muscles of N. granulata. In short-term experiment and low dosages, melatonin increased the VO2, c-GCL activity and GSH content (p < 0.05) and decreased melatonin content (p < 0.05) without effects in ROS, ACAP and LPO (p > 0.05). Possibly, melatonin is acting in the ADS increasing its efficiency and/or acting in mitochondrial activity and/or through signaling muscles to increase its consumption. AFMK was only detected in the eyestalk and cerebroid ganglia. In high dosages melatonin effects decreased...

A method of achieving physiological plasma levels of melatonin in the chicken by oral administration

Noddegaard, F.; Kennaway, D.
Fonte: MUNKSGAARD INT PUBL LTD Publicador: MUNKSGAARD INT PUBL LTD
Tipo: Artigo de Revista Científica
Publicado em //1999 EN
Relevância na Pesquisa
37.38%
In avian species it has been difficult to elucidate the precise role of melatonin in the control of reproductive cycles. We have investigated ways of administering melatonin to immature chickens and laying hens to achieve physiological levels and patterns in blood simulating either short or long photoperiods. Melatonin was administered orally using different doses and various ways of applying melatonin to the feed. For subcutaneous injections, melatonin was suspended in propylene glycol or grape seed oil. Melatonin always appeared in the first blood samples taken within an hour of administration. When melatonin was absorbed into feed pellets or whole wheat, a high initial plasma concentration was reached, followed by a rapid decrease over the ensuing 2-3 hr, but was still detectable as long as 24 hr after administration. For example, doses of 300 microg/kg produced 15 nM, which is more than ten times higher than the nocturnal peak concentration. When melatonin was absorbed into cracked wheat grains that were subsequently washed with ethanol, the initial transitory peak was eliminated, levels in plasma were sustained for at least 12 hr in the normal nocturnal range (750 pM), and no melatonin (< 60 pM) was present 18 hr later. When injected (2 microg/bird)...

Effect of stimulation of endogenous melatonin secretion during constant light exposure on 6-sulphatoxymelatonin rhythmicity in rats

Kennaway, D.; Rowe, S.
Fonte: Blackwell Munksgaard Publicador: Blackwell Munksgaard
Tipo: Artigo de Revista Científica
Publicado em //2000 EN
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37.4%
When light is presented unexpectedly at night to rats, melatonin production and secretion is acutely inhibited and the time of onset of production on the subsequent night is altered. In a series of experiments, we examined the effects of 6-12 hr light (200 lux) at night on melatonin metabolite excretion (6-sulphatoxymelatonin, aMT.6S). During the light exposure, we administered isoproterenol to stimulate endogenous production of melatonin by the pineal gland to determine if replacement of melatonin would block any phase shifting effects of the light. Exposure to 6 hr of light either during the first or second half of the night suppressed aMT.6S excretion during the light treatment and delayed the onset of melatonin secretion by 3.7 +/- 0.6 and 2.5 +/- 0.6 hr, respectively, compared to a change of 0.5 +/- 0.1 hr in animals maintained in darkness. Twelve hours light exposure (i.e. one night of continuous light) suppressed aMT.6S excretion completely and resulted in a delay in the onset the next night of 2.1 +/- 0.7 hr. When propranolol (10 mg/kg) was administered at 2-hr intervals during darkness, aMT.6S excretion was suppressed throughout the night, but on the subsequent release into constant darkness the onset of excretion was not delayed (0.6 +/- 0.1 hr delay). Administration of isoproterenol (10 mg/kg) to animals in constant light...

Controlled-release melatonin implants delay puberty in rats without altering melatonin rhythmicity

Kennaway, D.; Rowe, S.
Fonte: MUNKSGAARD INT PUBL LTD Publicador: MUNKSGAARD INT PUBL LTD
Tipo: Artigo de Revista Científica
Publicado em //1997 EN
Relevância na Pesquisa
37.42%
There is increasing evidence that continuous availability of melatonin via implants can produce the same physiological changes in animals as timed administration of the hormone. The mechanisms underlying this apparent contradiction are not known. In an attempt to gain further understanding of the way continuous melatonin administration affects reproductive activity, the effects of melatonin implants on gonadal development and melatonin production were investigated in rats treated neonatally with testosterone. Five-day-old male rats maintained on a 12L:12D photoperiod were injected with 1 mg testosterone propionate to induce photo-responsiveness and implanted at 21 days of age with novel melatonin implants designed to raise the daytime blood melatonin concentration into the nighttime range, i.e., from less than 60 pM in the controls during the day to 380 +/- 33 pM in the implanted rats. Following 21 days treatment, seminal vesicle and ventral prostate weights of implanted rats were significantly less than the controls (27.0 +/- 1.9 vs. 18.5 +/- 1.5 mg/ 100 g BW (P = 0.003) and 33.8 +/- 2.1 vs. 26.7 +/- 2.2 mg/100 g BW (P = 0.02), respectively). To determine the effect of the implants upon melatonin production, urine was collected at hourly intervals during the last four days of the experiment and the hourly 6-sulphatoxymelatonin (aMT.6S) excretion rate was determined. Rats bearing melatonin implants maintained a rhythm of aMT.6S excretion in 12L:12D...

Effects of subchronic and chronic melatonin treatment on somatostatin binding and its effects on adenylyl cyclase activity in the rat frontoparietal cortex

Izquierdo Claros, Rosa María; Boyano Adánez, María del Carmen; Arilla Ferreiro, Eduardo
Fonte: Journal of Pineal Research Publicador: Journal of Pineal Research
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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37.4%
Melatonin and somatostatin are known to exert similar effects on locomotor activity. We have previously demonstrated that acute melatonin treatment regulates somatostatin receptor function in the rat frontoparietal cortex. However, the effects of subchronic and chronic melatonin treatment on the somatostatin receptor-G protein–adenylyl cyclase system in the rat frontoparietal cortex are unknown. Melatonin was administered subcutaneously at a daily dose of 25 μg/kg for 4 days, 1 wk or 2 wk. Twenty-four hours after the last injection, the animals were sacrificed. Melatonin did not alter the somatostatin-like immunoreactivity content in the frontoparietal cortex from control and melatonin-treated rats during any of the previously indicated periods. Four days of melatonin administration induced both an increase in the number of [125I]-Tyr11-somatostatin receptors and a decrease in the affinity of somatostatin for its receptors in frontoparietal cortical membranes. The increased number of somatostatin receptors in the melatonin-treated rats was associated with an increased capacity of somatostatin to inhibit basal and forskolin-stimulated adenylyl cyclase activity. Melatonin administration for 4 days induced a higher adenylyl cyclase activity both under basal conditions and after direct stimulation of the enzyme with forskolin. No significant differences were observed in the function of Gi proteins in the 4-day melatonin-treated rats. Western blot analyses showed that the 4-day melatonin treatment reduced Giα2 levels...

Determinants and methods of assessment of melatonin levels among rotating shift nurses

Grundy, Anne Louise
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 1477596 bytes; application/pdf
EN; EN
Relevância na Pesquisa
37.45%
Background: Long-term night shift work has been associated with multiple cancer sites, including breast, prostate, colon and endometrial. The mechanism for this effect is hypothesized to include the hormone melatonin; where increased light at night exposure during shift work reduces melatonin production and decreased melatonin levels are associated with increased cancer risk. In addition, physical activity has been shown to reduce cancer risk and existing laboratory studies indicate it has the potential to influence melatonin levels. Methods: A cross-sectional study of light intensity exposure, physical activity and melatonin levels was conducted among 61 rotating shift nurses at Kingston General Hospital. Light intensity exposure was measured using a light intensity data logger and melatonin concentrations were measured from urine and saliva samples, collected over a 24-hour period. Physical activity was assessed from a study questionnaire and one-day diary. Results: A statistically significant inverse association between light exposure and urinary melatonin levels was observed; however, the relationship was no longer significant when stratified by shift group. Analysis of salivary melatonin levels demonstrated that circadian rhythms of melatonin production in night workers were not altered in timing...

Resposta ergogênica da melatonina no nadir e acrofase da atividade espontânea e suas consequências na atividade da via IKK/NF-kB e dano tecidual muscular; Ergogenic response of melatonin ar nadir and acrophase of spontaneous activity and its consequences on IKK/NF-kB pathway activity and muscle tissue damage

Wladimir Rafael Beck
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/02/2015 PT
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37.4%
Sintetizada principalmente na glândula pineal de mamíferos, a melatonina é uma indoleamina responsável classicamente por sincronizar o ritmo circadiano prioritariamente por meio do ciclo geofísico terrestre de luminosidade. A identificação de diversas outras propriedades a tornou alvo recente de estudos que buscam conhecer seus efeitos sobre o exercício físico. Otimizar o uso de substratos energéticos durante o esforço, inibir inflamação e lesões teciduais exacerbadas são propriedades documentadas na literatura e consideradas como potencialmente ergogênicas, fato que compreende um capítulo controverso da atual literatura científica esportiva. Diante disso, o objetivo da tese foi determinar a capacidade ergogênica da melatonina em exercício exaustivo sob intensidade de máxima capacidade aeróbia (tlim) iniciados no nadir e acrofase da atividade espontânea (AE), identificando os efeitos dessas condições sobre a atividade da via inflamatória IKK/NF-'capa'B em músculo esquelético oxidativo, marcadores metabólicos, hematológicos e de lesão tecidual de ratos nadadores. Para isso, dois procedimentos foram originalmente padronizados: i) construção de aparato e confecção de rotina de cálculos para a determinação do ritmo circadiano da AE e ii) teste incremental (TI) para estimativa da intensidade de máxima capacidade aeróbia de ratos nadadores. Os animais foram mantidos sob condições ambientais adequadas e sob ciclo claro/escuro de 12 horas iniciando às 06:00h com luz clara (560nm; 60lux). A determinação da AE ao longo do dia foi utilizada para definição dos horários em que seriam iniciados todos os procedimentos...

Estudio de la participación de la melatonina en la fisiología de la retina de Hámster Dorado; Participation of melatonin in the physiology of the golden hamster retina

Faillace, María Paula
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //1996 SPA
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La melatonina caracterizada originalmente en la glándula pineal fue más tarde identificada en la retina de diversas especies, así como las enzimas involucradas en su síntesis, la serotonina-N-acetiltransferasa (NAT) y la hidroxiindol-O-metiltransferasa (HIOMT). El hámster dorado ha sido considerado frecuentemente el modelo clásico para el estudio de la melatonina pineal, sin embargo, la melatonina retiniana en esta especie ha recibido relativamente poca atención. El objetivo de este trabajo de tesis consistió en examinar la biosíntesis del metoxiindol en la retina del hámster, así como elucidar algunos de los mecanismos involucrados en la regulación de su síntesis y su posible rol fisiológico a nivel local. En este sentido, se describe por primera vez la presencia de un ritmo en el contenido retiniano de melatonina en el hámster dorado, con valores máximos en la segunda mitad de la noche. La síntesis de melatonina en la retina del hámster es independiente de la actividad pineal. Asimismo, se demuestra la capacidad de las retinas aisladas de sintetizar melatonina. La síntesis de melatonina es regulada directamente por la señal fótica ambiental, sin indicación de la existencia de un ritmo de naturaleza endógena en los experimentos realizados en este trabajo. El GABA...

Melatonin reduces neuronal loss and cytoskeletal deterioration: implications for Psychiatry

Reiter,Russel J.; Benitez-King,Gloria
Fonte: Instituto Mexicano de Psiquiatría Ramón de la Fuente Publicador: Instituto Mexicano de Psiquiatría Ramón de la Fuente
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2009 EN
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This review article summarizes the potential role of circadian rhythmicity and melatonin in psychiatric disorders. The melatonin rhythm, with high blood levels at night and low values during the day, is a reflection of the biological clock, i.e., the suprachiasmatic nucleus (SCN). The SCN receive information about the prevailing light: dark conditions from specialized ganglion cells (only 1-2% of the total ganglion cells) in the retina. These unique cells contain a newly-discovered photopigment, melanopsin, which responds to a rather narrow band width of light that peaks at roughly 480 nm. The axons of these ganglion cells project via the retinohypothalamic tract through the optic nerve to the SCN, located just above the optic chiasm in the anterior hypothalamus. Via this pathway, light detected by the retina synchronizes the circadian clock to precisely 24 hours. In the absence of light, i.e., darkness, the SCN signals the pineal gland to produce melatonin via a complex neural pathway that involves fibers that project from the hypothalamus to the preganglionic sympathetic neurons in the intermediolateral cell column of the upper thoracic cord. Axons of these neurons exit the spinal cord to eventually synapse on neurons in the superior cervical ganglia. Then...