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Master's Dissertation
DOI
10.11606/D.25.2014.tde-16072014-134512
Document
Author
Full name
Priscila Aparecida Teixeira de Muno Barreta
Institute/School/College
Knowledge Area
Date of Defense
Published
Bauru, 2014
Supervisor
Committee
Buzalaf, Marilia Afonso Rabelo (President)
Antonio, Ligia Subitoni
Oliveira, Rodrigo Cardoso de
Title in Portuguese
Influência da administração concomitante de fluoreto através da água de beber no metabolismo e incorporação de chumbo em ratos: estudo dose-resposta
Keywords in Portuguese
Ácido fluorosilícico
Água
Chumbo
Fluoreto de sódio
Metabolismo
Ratos
Abstract in Portuguese
O objetivo deste estudo foi avaliar os níveis de F e Pb circulantes, excretados e incorporados no tecido ósseo em ratos expostos simultaneamente ao F e Pb através da água de beber desde a gestação, levando-se em consideração diferentes doses de Pb e F e dois tipos de sais fluoretados. Para tal, 280 ratos Wistar machos foram divididos em 28 grupos contendo 10 animais cada. As diferenças entre os grupos foram as concentrações, na água de beber, de Pb (0, 1, 10 ou 30 mg/L) e de F (0, 5, 50 ou 100 mg/L), em dois tipos de sais (NaF ou H2SiF6). Os animais foram expostos ao tratamento desde a gestação até completarem 80 dias de vida, quando foram eutanasiados e o sangue foi removido para análise de Pb e F (no sangue total e plasma, respectivamente). Também foi coletado o fêmur direito, para análises de F e Pb. Ainda foram coletadas amostras de urina e fezes (24 horas) dos animais alojados em gaiolas metabólicas (n=6 por grupo) a cada 14 dias, desde o desmame até a eutanásia, para análises de F e Pb. As análises de Pb foram feitas por ICP-MS e as análises de F foram feitas com o eletrodo, após difusão facilitada por hemametildisiloxano (plasma, fêmur e fezes) ou pelo método direto (urina). Os dados foram analisados por ANOVA a 3 critérios, seguida pela teste de Tukey (p<0,05). Observou-se que o composto fluoretado, a concentração de F na água e a concentração de Pb na água interferiram na retenção de F e de Pb no organismo, indicando que a administração concomitante de F e Pb através da água de beber é capaz de aumentar a incorporação de F e de Pb no tecido ósseo e que a excreção urinária e fecal destes elementos não é suficiente para explicar a maior retenção dos mesmos no organismo. Quando o F foi adicionado à água na forma de H2SiF6, concentrações significativamente mais altas de F foram observadas no plasma e osso, e quantidades significativamente menores de F foram excretadas através da urina, aumentando a biodisponibilidade do F no organismo. Maior biodisponibilidade do Pb também foi observada quando o H2SiF6 foi utilizado em comparação ao NaF, com concentrações significativamente maiores de Pb no osso, a despeito de uma maior excreção urinária e fecal de Pb. Estes resultados confirmam achados de estudos epidemiológicos e de prova-de-conceito prévios de que a exposição concomitante a sílicofluoretos e Pb é capaz de aumentar a biodisponibilidade do Pb, assim como também do F no organismo. Estudos adicionais devem ser conduzidos para investigar os mecanismos que levam a estes efeitos
Title in English
Influence of concomitant fluoride via drinking water in the metabolism and incorporation of lead in rats: dose-response study
Keywords in English
Fluorosilicic Acid Metabolism
Lead
Rats
Sodium Fluoride
Water
Abstract in English
The aim of this study was to evaluate the circulating levels of F and Pb, as well as the levels of F and Pb excreted and uptaken by bone, in rats co-exposed to F and Pb from the drinking water, taking into account different doses of Pb and F and two types of fluoridated salts. For this purpose, 280 male Wistar rats were divided into 28 groups (n=10). The differences among the groups were the concentrations of Pb (0, 1 , 10 or 30 mg/L ) and F [0, 5, 50 or 100 mg/L in two types of salts (NaF or H2SiF6)] added in the drinking water to which the females and their offspring were exposed, 1 week before mating until the pups completed 80 days of life. At 80 days of age, the animals were euthanized. Blood was collected for Pb and F analysis (whole blood and plasma, respectively). The right femur was also collected for Pb and F analyses. In addition, throughout the experimental period, urine and feces were collected from the animals housed in metabolic cages (n=6/group) every 14 days, for F and Pb analyses. Pb was analyzed by ICP-MS and F was measured with the electrode, after hexamethyldisiloxane-facilitated diffuson (plasma, femur and feces) or by the direct method (urine). Data were analyzed by 3-way ANOVA and Tukey´s test (p<0.05). It was observed that the F compound, the F concentration and the Pb concentration in the drinking water interfered in the retention of Pb and F in the organism. These data indicate that co-exposure to F and Pb from the drinking water increases the F and Pb uptake by bone. This cannot be completely explained by the urinary and fecal excretion of F and Pb. When F was added to the water as H2SiF6, significantly higher F concentrations were observed in plasma and bone, while significantly lower amounts of F were excreted through urine, increasing the bioavailability of F in the organism. Also higher bioavailability of Pb was observed upon administration of H2SiF6 when compared to NaF (significantly higher concentrations of Pb were observed in bone, despite the excretion of Pb from feces and urine was higher). These results reinforce the findings of previous epidemiological and proof-of-concept studies that report increased bioavailability of Pb and F in the organism upon coexposure to silicofluorides and Pb. Additional studies should be conducted to investigate the mechanisms that lead to these effects.
 
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Publishing Date
2014-07-16
 
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