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Influence of the pineal gland on the physiology, morphometry and morphology of pancreatic islets in rats BJB
LIMA,L. M. B. de; REIS,L. C. dos; LIMA,M. A. de.
To investigate the influence of the pineal gland through melatonin secretion on the physiological and morphological parameters of pancreatic islets, we studied the plasma biochemistry and morphological and morphometric characteristics of the endocrine pancreas of male Wistar rats. The animals were distributed into five groups of ten rats each: NC - normal control group; NS - sham-operated group; Px (25) - pinealectomised group, studied 15-25 days after surgery; Px (70) - pinealectomised group, studied 60-70 days after surgery; ALX - alloxan monohydrate-treated group. Data are analyzed statistically by ANOVA and by the Kruskal-Wallis test. Although there was no significant difference in plasma glucose or insulin levels between the Px (25), Px (70) and NC...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Pinealectomy; Melatonin; Pancreatic islet; Rat; Morphology.
Ano: 2001 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0034-71082001000200018
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Effect of melatonin on the functional recovery from experimental traumatic compression of the spinal cord BJMBR
Schiaveto-de-Souza,A.; da-Silva,C.A.; Defino,H.L.A.; Bel,E.A.Del.
Spinal cord injury is an extremely severe condition with no available effective therapies. We examined the effect of melatonin on traumatic compression of the spinal cord. Sixty male adult Wistar rats were divided into three groups: sham-operated animals and animals with 35 and 50% spinal cord compression with a polycarbonate rod spacer. Each group was divided into two subgroups, each receiving an injection of vehicle or melatonin (2.5 mg/kg, intraperitoneal) 5 min prior to and 1, 2, 3, and 4 h after injury. Functional recovery was monitored weekly by the open-field test, the Basso, Beattie and Bresnahan locomotor scale and the inclined plane test. Histological changes of the spinal cord were examined 35 days after injury. Motor scores were progressively...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Spinal cord injury; Melatonin; Functional recovery.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2013000400348
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Ghost protein damage by peroxynitrite and its protection by melatonin BJMBR
Di Mascio,P.; Dewez,B.; Garcia,C.R.S..
We have studied the effect of peroxynitrite (ONOO-) on the membrane cytoskeleton of red blood cells and its protection by melatonin. Analysis of the protein fraction of the preparation by SDS-PAGE revealed a dose-dependent (0-600 µM ONOO-) disappearance at pH 7.4 of the main proteins: spectrin, band 3, and actin, with the concomitant formation of high-molecular weight aggregates resistant to reduction by ß-mercaptoethanol (2%) at room temperature for 20 min. These aggregates were not solubilized by 8 M urea. Incubation of the membrane cytoskeleton with ONOO- was characterized by a marked depletion of free sulfhydryl groups (50% at 250 µM ONOO-). However, a lack of effect of ß-mercaptoethanol suggests that, under our conditions, aggregate formation is not...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Peroxynitrite; Melatonin; Spectrin; Protein; Ghost; Thiols.
Ano: 2000 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2000000100002
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Effect of melatonin administration on subjective sleep quality in chronic obstructive pulmonary disease BJMBR
Nunes,D.M.; Mota,R.M.S.; Machado,M.O.; Pereira,E.D.B.; de Bruin,V.M.S.; de Bruin,P.F.C..
Disturbed sleep is common in chronic obstructive pulmonary disease (COPD). Conventional hypnotics worsen nocturnal hypoxemia and, in severe cases, can lead to respiratory failure. Exogenous melatonin has somnogenic properties in normal subjects and can improve sleep in several clinical conditions. This randomized, double-blind, placebo-controlled study was carried out to determine the effects of melatonin on sleep in COPD. Thirty consecutive patients with moderate to very severe COPD were initially recruited for the study. None of the participants had a history of disease exacerbation 4 weeks prior to the study, obstructive sleep apnea, mental disorders, current use of oral steroids, methylxanthines or hypnotic-sedative medication, nocturnal oxygen...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Chronic obstructive pulmonary disease; Melatonin; Sleep.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2008001000016
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Evolution of circadian organization in vertebrates BJMBR
Circadian organization means the way in which the entire circadian system above the cellular level is put together physically and the principles and rules that determine the interactions among its component parts which produce overt rhythms of physiology and behavior. Understanding this organization and its evolution is of practical importance as well as of basic interest. The first major problem that we face is the difficulty of making sense of the apparently great diversity that we observe in circadian organization of diverse vertebrates. Some of this diversity falls neatly into place along phylogenetic lines leading to firm generalizations: i) in all vertebrates there is a "circadian axis" consisting of the retinas, the pineal gland and the...
Tipo: Info:eu-repo/semantics/other Palavras-chave: Circadian rhythms; Evolution; Vertebrates; Pineal; SCN; Retina; Melatonin.
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997000300003
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The expression of melanopsin and clock genes in Xenopus laevis melanophores and their modulation by melatonin BJMBR
Bluhm,A.P.C.; Obeid,N.N.; Castrucci,A.M.L.; Visconti,M.A..
Vertebrates have a central clock and also several peripheral clocks. Light responses might result from the integration of light signals by these clocks. The dermal melanophores of Xenopus laevis have a photoreceptor molecule denominated melanopsin (OPN4x). The mechanisms of the circadian clock involve positive and negative feedback. We hypothesize that these dermal melanophores also present peripheral clock characteristics. Using quantitative PCR, we analyzed the pattern of temporal expression of Opn4x and the clock genes Per1, Per2, Bmal1, and Clock in these cells, subjected to a 14-h light:10-h dark (14L:10D) regime or constant darkness (DD). Also, in view of the physiological role of melatonin in the dermal melanophores of X. laevis, we determined...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Xenopus laevis; Dermal melanophores; Melatonin; Melanopsin; Per1; Per2; Bmal1; Clock.
Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2012000800007
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Indole ring oxidation by activated leukocytes prevents the production of hypochlorous acid BJMBR
Ximenes,V.F.; Paino,I.M.M.; Faria-Oliveira,O.M.M. de; Fonseca,L.M. da; Brunetti,I.L..
Hypochlorous acid (HOCl) released by activated leukocytes has been implicated in the tissue damage that characterizes chronic inflammatory diseases. In this investigation, 14 indole derivatives, including metabolites such as melatonin, tryptophan and indole-3-acetic acid, were screened for their ability to inhibit the generation of this endogenous oxidant by stimulated leukocytes. The release of HOCl was measured by the production of taurine-chloramine when the leukocytes (2 x 10(6) cells/mL) were incubated at 37ºC in 10 mM phosphate-buffered saline, pH 7.4, for 30 min with 5 mM taurine and stimulated with 100 nM phorbol-12-myristate acetate. Irrespective of the group substituted in the indole ring, all the compounds tested including indole,...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Leukocytes; Myeloperoxidase; Hypochlorous acid; Indole ring; Melatonin; Indole-3-acetic acid.
Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005001100003
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Melatonin and N-acetyl-serotonin cross the red blood cell membrane and evoke calcium mobilization in malarial parasites BJMBR
Hotta,C.T.; Markus,R.P.; Garcia,C.R.S..
The duration of the intraerythrocytic cycle of Plasmodium is a key factor in the pathogenicity of this parasite. The simultaneous attack of the host red blood cells by the parasites depends on the synchronicity of their development. Unraveling the signals at the basis of this synchronicity represents a challenging biological question and may be very important to develop alternative strategies for therapeutic approaches. Recently, we reported that the synchrony of Plasmodium is modulated by melatonin, a host hormone that is synthesized only during the dark phases. Here we report that N-acetyl-serotonin, a melatonin precursor, also releases Ca2+ from isolated P. chabaudi parasites at micro- and nanomolar concentrations and that the release is blocked by 250...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Malaria; Plasmodium; Calcium; Melatonin; Circadian rhythm; Host-parasite interaction.
Ano: 2003 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003001100016
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Effects of melatonin on the ovarian response to pinealectomy or continuous light in female rats: similarity with polycystic ovary syndrome BJMBR
Prata Lima,M.F.; Baracat,E.C.; Simões,M.J..
The current study was conducted to investigate the relationship between melatonin and chronic anovulation. Adult (3-4 months old) female Wistar rats were submitted to pinealectomy: group I: pinealectomized ovariectomized melatonin-treated (N = 10); group II: pinealectomized ovariectomized placebo-treated (N = 12); group III: pinealectomized light-treated placebo-treated(N = 10) or maintained under continuous light; group IV: maintained under continuous light, ovariectomized melatonin-treated (N = 22); group V: maintained under continuous light, ovariectomized placebo-treated (N = 10); group VI: maintained under continuous light placebo-treated (N = 10). In order to assess ovarian modifications, unilateral ovariectomy was performed during the fourth month...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Melatonin; Polycystic ovary syndrome; Pineal body; Anovulation.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2004000700007
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Long-term melatonin treatment reduces ovarian mass and enhances tissue antioxidant defenses during ovulation in the rat BJMBR
Chuffa,L.G.A.; Amorim,J.P.A.; Teixeira,G.R.; Mendes,L.O.; Fioruci,B.A.; Pinheiro,P.F.F.; Seiva,F.R.F.; Novelli,E.L.B.; Mello Júnior,W.; Martinez,M.; Martinez,F.E..
Melatonin regulates the reproductive cycle, energy metabolism and may also act as a potential antioxidant indoleamine. The present study was undertaken to investigate whether long-term melatonin treatment can induce reproductive alterations and if it can protect ovarian tissue against lipid peroxidation during ovulation. Twenty-four adult female Wistar rats, 60 days old (± 250-260 g), were randomly divided into two equal groups. The control group received 0.3 mL 0.9% NaCl + 0.04 mL 95% ethanol as vehicle, and the melatonin-treated group received vehicle + melatonin (100 µg·100 g body weight-1·day-1) both intraperitoneally daily for 60 days. All animals were killed by decapitation during the morning estrus at 4:00 am. Body weight gain and body mass index...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Melatonin; Ovary mass; Lipid peroxidation; Antioxidant defenses; Superoxide dismutase.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011000300007
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Probable effect of photoperiod on seasonal variation in the nuclear volume of the adrenal cortex of viscacha (Lagostomus maximus maximus) BJMBR
Ribes,A.C.; Mohamed,F.; Dominguez,S.; Delgado,M.; Scardapane,L.; Guzman,J.; Piezzi,R..
The neuroendocrine system regulates several organic functions such as reproduction, metabolism and adaptation to the environment. This system shows seasonal changes linked to the environment. The experimental model used in the present study was Lagostomus maximus maximus (viscacha). The reproduction of males of this species is photoperiod dependent. Twenty-four adult male viscachas were captured in their habitat at different times during one year. The adrenal glands were processed for light microscopy. Serial cuts were stained with hematoxylin-eosin for the morphometric study, and 100 nuclei of each zone of the adrenal cortex were counted per animal. Data were analyzed statistically by ANOVA and the Tukey test. The cells of the glomerulosa zone are...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Viscacha (Lagostomus maximus maximus); Adrenal; Glomerulosa; Fasciculata; Reticularis; Photoperiod; Morphometry; Melatonin.
Ano: 1999 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1999000900010
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Influence of melatonin on the development of functional nicotinic acetylcholine receptors in cultured chick retinal cells BJMBR
Sampaio,L.F.S.; Hamassaki-Britto,D.E.; Markus,R.P..
The influence of melatonin on the developmental pattern of functional nicotinic acetylcholine receptors was investigated in embryonic 8-day-old chick retinal cells in culture. The functional response to acetylcholine was measured in cultured retina cells by microphysiometry. The maximal functional response to acetylcholine increased 2.7 times between the 4th and 5th day in vitro (DIV4, DIV5), while the Bmax value for [125I]-alpha-bungarotoxin was reduced. Despite the presence of alpha8-like immunoreactivity at DIV4, functional responses mediated by alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors were observed only at DIV5. Mecamylamine (100 µM) was essentially without effect at DIV4 and DIV5, while dihydro-ß-erythroidine (10-100 µM) blocked...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Retina; Development; Nicotinic acetylcholine receptors; Alpha-bungarotoxin; Melatonin; Microphysiometry.
Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000400015
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Melatonin prevents inflammation and oxidative stress caused by abdominopelvic and total body irradiation of rat small intestine BJMBR
Guney,Y.; Hicsonmez,A.; Uluoglu,C.; Guney,H.Z.; Ozel Turkcu,U.; Take,G.; Yucel,B.; Caglar,G.; Bilgihan,A.; Erdogan,D.; Nalca Andrieu,M.; Kurtman,C.; Zengil,H..
We investigated the day-night differences in intestinal oxidative-injury and the inflammatory response following total body (TB) or abdominopelvic (AP) irradiation, and the influence of melatonin administration on tissue injury induced by radiation. Rats (male Wistar, weighing 220-280 g) in the irradiated groups were exposed to a dose of 8 Gy to the TB or AP region in the morning (resting period - 1 h after light onset) or evening (activity span - 13 h after light onset). Vehicle or melatonin was administered immediately before, immediately after and 24 h after irradiation (10, 2.0 and 10 mg/kg, ip, respectively) to the irradiated rats. AP (P < 0.05) and TB (P < 0.05) irradiation applied in the morning caused a significant increase in thiobarbituric...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Irradiation; Melatonin; Circadian rhythm; Oxidative stress; Thiobarbituric acid reactive substances; Myeloperoxidase.
Ano: 2007 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007001000002
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Effect of melatonin and time of administration on irradiation-induced damage to rat testes BJMBR
Take,G.; Erdogan,D.; Helvacioglu,F.; Göktas,G.; Ozbey,G.; Uluoglu,C.; Yücel,B.; Guney,Y.; Hicsonmez,A.; Ozkan,S..
The effect of ionizing irradiation on testes and the protective effects of melatonin were investigated by immunohistochemical and electron microscopic methods. Eighty-two adult male Wistar rats were divided into 10 groups. The rats in the irradiated groups were exposed to a sublethal irradiation dose of 8 Gy, either to the total body or abdominopelvic region using a 60Co source at a focus of 80 cm away from the skin in the morning or evening together with vehicle (20% ethanol) or melatonin administered 24 h before (10 mg/kg), immediately before (20 mg/kg) and 24 h after irradiation (10 mg/kg), all ip. Caspace-3 immunoreactivity was increased in the irradiated group compared to control (P < 0.05). Melatonin-treated groups showed less apoptosis as...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Testes; Gamma-irradiation; Melatonin; Immunohistochemistry; Electron microscopy.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2009000700006
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Effects of melatonin on DNA damage induced by cyclophosphamide in rats BJMBR
Ferreira,S.G.; Peliciari-Garcia,R.A.; Takahashi-Hyodo,S.A.; Rodrigues,A.C.; Amaral,F.G.; Berra,C.M.; Bordin,S.; Curi,R.; Cipolla-Neto,J..
The antioxidant and free radical scavenger properties of melatonin have been well described in the literature. In this study, our objective was to determine the protective effect of the pineal gland hormone against the DNA damage induced by cyclophosphamide (CP), an anti-tumor agent that is widely applied in clinical practice. DNA damage was induced in rats by a single intraperitoneal injection of CP (20 or 50 mg/kg). Animals received melatonin during the dark period for 15 days (1 mg/kg in the drinking water). Rat bone marrow cells were used for the determination of chromosomal aberrations and of formamidopyrimidine DNA glycosylase enzyme (Fpg)-sensitive sites by the comet technique and ofXpf mRNA expression by qRT-PCR. The number (mean ± SE) of...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Melatonin; Cyclophosphamide; Chromosomal aberration; DNA fragmentation; Comet assay; Xpf expression.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2013000300278
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Melatonin modulation of presynaptic nicotinic acetylcholine receptors located on short noradrenergic neurons of the rat vas deferens: a pharmacological characterization BJMBR
Zago,W.M.; Markus,R.P..
Melatonin, the pineal hormone produced during the dark phase of the light-dark cycle, modulates neuronal acetylcholine receptors located presynaptically on nerve terminals of the rat vas deferens. Recently we showed the presence of high affinity nicotine-binding sites during the light phase, and low and high affinity binding sites during the dark phase. The appearance of the low affinity binding sites was due to the nocturnal melatonin surge and could be mimicked by exposure to melatonin in vitro. The aim of the present research was to identify the receptor subtypes responsible for the functional response during the light and the dark phase. The rank order of potency of agonists was dimethylphenylpiperazinium (DMPP) = cytisine &gt; nicotine &gt;...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Melatonin; Neuronal nicotinic acetylcholine receptors; Mecamylamine; Methyllycaconitine; Vas deferens.
Ano: 1999 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1999000800010
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Bioisosteric modification on melatonin: synthesis of new naphthalene derivatives, in vitro antioxidant activity and cytotoxicity studies BJPS
Shirinzadeh,Hanif; Ghalia,Mohammed; Tascioglu,Alev; Adjali,Ferial Intissar; Gunesacar,Gulsen; Gurer-Orhan,Hande; Suzen,Sibel.
Melatonin (MLT) is a strong free radical scavenger that protects the body from the deleterious effects of excess oxidants. Synthesis of MLT analogue compounds with antioxidant potency has recently attracted the interest of researchers. In general, the strategy consists of modifying the groups in the different sites of the indole ring or replacing the indole ring with an analogue. As part of our ongoing research, the antioxidant capacity and cytotoxicity of newly synthesized MLT analogue naphthalene derivatives were evaluated. The radical scavenging activity was tested by a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Most of the synthesized compounds showed significant antioxidant activity in comparison to MLT. The structure-activity relationship was...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Antioxidant; Cytotoxic; Melatonin; MTT; DPPH.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502020000100550
Registros recuperados: 37
Primeira ... 12 ... Última
 

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