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Influence of concomitant fluoride via drinking water in the metabolism and incorporation of lead in rats: dose-response study

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Author(s):
Priscila Aparecida Teixeira de Muno Barreta
Total Authors: 1
Document type: Master's Dissertation
Press: Bauru.
Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
Defense date:
Examining board members:
Marilia Afonso Rabelo Buzalaf; Ligia Subitoni Antonio; Rodrigo Cardoso de Oliveira
Advisor: Marilia Afonso Rabelo Buzalaf
Abstract

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. (AU)

FAPESP's process: 10/13216-3 - Influence of co-administration of fluoride from drinking water on the metabolism and uptake of lead in rats: dose-response study
Grantee:Priscila Aparecida Teixeira de Muno Barreta
Support Opportunities: Scholarships in Brazil - Master