Navegando por Assunto "Melatonina"

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Acesso aberto (Open Access)
Influence of melatonin on the development of functional nicotinic acetylcholine receptors in cultured chick retinal cells
(2005-04) SAMPAIO, Lucia de Fatima Sobral; HAMASSAKI, Dânia Emi; MARKUS, Regina Pekelmann
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-a-bungarotoxin was reduced. Despite the presence of a8-like immunoreactivity at DIV4, functional responses mediated by a-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 the response to acetylcholine (3.0 nM-2.0 µM) only at DIV4, with no effect at DIV5. Inhibition of melatonin receptors with the antagonist luzindole, or melatonin synthesis by stimulation of D4 dopamine receptors blocked the appearance of the a-bungarotoxin-sensitive response at DIV5. Therefore, a-bungarotoxin-sensitive receptors were expressed in retinal cells as early as at DIV4, but they reacted to acetylcholine only after DIV5. The development of an a-bungarotoxin-sensitive response is dependent on the production of melatonin by the retinal culture. Melatonin, which is produced in a tonic manner by this culture, and is a key hormone in the temporal organization of vertebrates, also potentiates responses mediated by a-bungarotoxin-sensitive receptors in rat vas deferens and cerebellum. This common pattern of action on different cell models that express a-bungarotoxin-sensitive receptors probably reflects a more general mechanism of regulation of these receptors.
Acesso aberto (Open Access)
Localização do receptor de melatonina Mel1a e da enzima NRH: quinona redutase 2 em embrião e retinas inteiros de Kinosternon scorpioides
(Universidade Federal do Pará, 2014-06-27) SILVA, Renata Nunes; SAMPAIO, Lucia de Fatima Sobral; http://lattes.cnpq.br/7145234400169550
The pineal and others tissues produced hormone melatonin synchronizes biological clocks with dark light environmental cycle. This hormone has functions on development via Mel1a melatonin receptor and NRH: quinona redutase 2 (QR2) enzyme. The present aim was to initiate an investigation about the localization of the both Mel1a melatonin receptor and QR2 enzyme melatonin binding site in vertebrate development. We taken as a model the fresh water turtle Kinosternon scorpioides (muçuã). Whole 21 days embryos (E21) and retinas from E21 and 60 days posthatched (PH) muçuãs respectively were assayed by immunoassays and immunohistochemistry, using commercial antibodies and the results were revealed by Texas red fluorescence. As Mel1a melatonin receptor as QR2 enzyme were localized in important external morphological characters in E21 and in retinas from both E21 and PH. Results showed Mel1a melatonin receptor in maxillary, mandibula, eye contour, Iris, choroide fissure, neck, elongated forelimb and hindlimb, developing carapace, beyond of the internal part of the tail bud. QR2 fluorescent signals in whole E21 embryos were in the following morphological external characters. In head, QR2 is at maxillary region; in the eye at lens and iris; in elongated forelimb and hindlimb; and in tail bud. No fluorescence was observed in negative controls incubated without the primary antibody. In conclusion, our achievers suggest that melatonin participates in Kinosternon scorpioides development as in ossification, hole of the Mella receptor, as in xenobiotic protection, hole of the QR2 enzyme. Melatonin functions on turtle development disclose are only starting, but we found some interesting answers and future investigations arise from these studies.
Acesso aberto (Open Access)
Melatonina previne danos cerebrais e déficits cognitivos induzidos pela infecção por Plasmodium berghei anka em modelo murino de malária cerebral
(Universidade Federal do Pará, 2021-05) ATAIDE, Brenda Jaqueline de Azevedo; OLIVEIRA, Karen Renata Herculano Matos; http://lattes.cnpq.br/3032008039259369
Cerebral malaria is characterized by permanent cognitive impairments in Plasmodium-infected children. Antimalarial therapies show little effectiveness to avoid neurological deficits and nervous tissue alterations elicited by severe malaria. Melatonin is a well-recognized endogenous hormone involved in the control of brain functions and maintenance of blood–brain barrier integrity. The current study has evaluated the effect of melatonin on the histological alterations, blood–brain barrier leakage, and neurocognitive impairments in mice developing cerebral malaria. Swiss mice infected with Plasmodium berghei ANKA strain was used as cerebral malaria model. Melatonin treatment (5 and 10 mg/kg) was performed for four consecutive days after the infection, and data have shown an increased survival rate in infected mice treated with melatonin. It was also observed that melatonin treatment blocked brain edema and prevented the breakdown of blood–brain barrier induced by the Plasmodium infection. Furthermore, hematoxylin and eosin staining revealed that melatonin mitigates the histological alterations in Plasmodium-infected animals. Melatonin was also able to prevent motor and cognitive impairments in infected mice. Taken together, these results show for the first time that melatonin treatment prevents histological brain damages and neurocognitive alterations induced by cerebral malaria
Acesso aberto (Open Access)
Polimorfismos na região promotora, Éxon I e Éxon II do gene do receptor da melatonina associados às características reprodutivas em búfalas na Amazônia
(Universidade Federal do Pará, 2015-06-18) BARBOSA, Elizabeth Machado; RIBEIRO, Haroldo Francisco Lobato; http://lattes.cnpq.br/1614582293203770
The buffaloes production in the Pará state have is a high representative activity to the regional economy and production of meat, milk and dairy products. Therefore, it is necessary to develop new technologies that increase the enjoyment of the production and reproduction of buffaloes in the Amazon region. Thus, the objectives of this research thesis was to characterize the promoter region of the melatonin receptor gene 1 (MTRN1A) and identify polymorphisms in exons I and II of that gene and link them to reproductive traits that have economic importance in buffaloes in the region Amazon. Were collected 400 buffaloes samples and 60 animals were used to characterize the promoter region, 140 to detect the polymorphism (SNPs) in exon II and 77 to detect the polymorphism in exon I. DNA extraction was peformed by phenol method. Then were selected different primers to make Polymerase Chain Reaction (PCR). The promoter region was sequenced MTRN1A a total of 1621 base pairs by the Sanger method, polymorphism in exon II was detected by PCR-RFLP (Restriction Fragment Length Polymorphism) with HpaI enzyme and the polymorphism exon I was found by sequencing DNA by Sanger method. Allele and genotype frequencies of all SNPs were evaluated, the inbreeding coefficient (Fis) and the likelihood of Hardy-Weinberg equilibrium. SNPs in the promoter region and exon I have been associated with reproductive traits of buffaloes by ANOVA or Student's t test and / or chisquare test. The significance level was 0,05. 26 SNPs were detected in the promoter region at positions -1511 (C → T), -1465 (G → T), -1422 (A → G), -1411 (G → A), -1395 (G → T), - 1298 (A → G) -1295 (G → A) -1242 (C → A) -1150 (C → T), -1 147 (G → C) -1136 (A → G) -911 ( G → A), -909 (A → G) -724 (C → G) -656 (A → C) -649 (C → T), -644 (G → A), -511 (A → C) -481 (G → A), -425 (C → T) -395 (G → A), -383 (G → T), -254 (C → T) -206 (T → C) , -133 (T → G) and -94 (C → T) and a deletion unit (ACAA) at position -1483. Of the total detected SNPs, 75% of the wild alleles tiveral frequencies greater than 0,5. For the characteristic interval between calving (IEP), only five SNPs (-1298, -1136, -911, -724 and - 656) were significantly associated (P <0.05) and three SNPs (-1395, -724 and -94) were significantly associated (P <0.05) with the characteristic age at first calving (IPP) and none for the characteristic concentration of deliveries (P> 0.05). A total of 11 SNPs was strongly associated with binding factors in gene regulation. The SNP in exon II by PCR-RFLP (HpaI) at position 306 (T → C), the most frequent allele T in Upland animals (0,529) and C in lowland animals, the two populations showed coefficients Fis inbreeding (0,040 and 0,091, respectively) and strong deviations from Hardy-Weinberg equilibrium (P> 0.05). The mutation occurs at codon 106 and is the sinonímio type without changing the messenger RNA handles structure. The SNP in exon I was detected at position 62 (T → C) and of the non sinonímio, exchanging of Leucine to Proline. The mutant allele was the most frequent C (0,623) inbreeding coefficient Fis = 0.397 and Hardy-Weinberg deviations (P <0.05). None of the genotypes were associated with calving interval and age at first birth (P> 0.05). Therefore, SNPs are strong candidates for selection, but it would be interesting to evaluate them in other herds in the Amazon region and / or in other regions of Brazil and / or other countries to effect them as excellent molecular markers for reproductive traits of buffalo.
Acesso aberto (Open Access)
Preferência Claro/Escuro em Danio rerio: Efeitos da Melatonina Sobre o Horário da Coleta e de Regime de Luz
(Universidade Federal do Pará, 2014-12-12) DIAS, Cláudio Alberto Gellis De Mattos; GOUVEIA JUNIOR, Amauri; http://lattes.cnpq.br/1417327467050274
Danio rerio is a widely used animal model for behavioral experiments in white / black tanks. The white side of the aquarium seems to cause aversion and the preference seems to be to stay longer on the dark side. Melatonin is a indoleamine which influence the physiological functioning of fish. The aims of this work are: to survey the literature on melatonin and its correlation with fishes and Danio rerio; compare the efficiency of two apparatuses insulation in behavioral tests; testing the influence of four periods of the day and five photoperiods response variation in Zebrafish to light-dark test; compare the time spent on each side of the aquarium test period, subjects isolated on a photoperiod of 12/12 hours with exposure to seven different concentrations of melatonin; statistically comparing the sample into quartiles within each concentration; and statistically compare the sample into quartiles among the first, second and third quartiles of each concentration. The Zebrafish and the fishes seem to have their physiology and behavior influenced by melatonin (both endogenous as exogenous). Both apparatuses isolation proved to be equally effective for behavioral tests. Luminosity seems to drag the Zebrafish circadian cycle, reducing their aversion to the white side of the aquarium, photoperiod 12/12 hour period and night collection. Melatonin seems to influence the change caused by photoperiod, decreasing or canceling the dragging. In our sample seems to be subpopulations that respond differently to exposure to the same concentration of melatonin. Studies with specific strains of Zebrafish and with a wider range of concentrations of melatonin appear to be necessary to identify the specific dosage possible to counteract the performance in light entrainment of the circadian cycle in Danio rerio.