Physical exercise ameliorates the toxic effect of fluoride on the insulin-glucose system.

Daily intake of water with fluoride concentrations >1.5 mg/l produces insulin resistance (IR). On the other hand, physical activity increases insulin sensitivity in the muscle. Therefore, the aim of this study was to evaluate the effect of physical activity on IR in rats treated with sodium fluoride (NaF) in drinking water. Sprague-Dawley rats were divided into three groups (n=10/group): Control (drinking water without NaF), NaF (drinking water with NaF 15 mg/l for 30 days), and Exercise (daily running on a treadmill for 60 min at 2.25 m/min and drinking water with NaF 15 mg/l for 30 days). IR was evaluated with the homeostasis model assessment-IR (HOMA-IR) index using fasting plasma levels of glucose and insulin. IR increased in rats treated with 15 mg/l NaF in drinking water. A decrease in IR was observed in rats that performed physical activity and drank water with 15 mg/l NaF; the Exercise group also showed an increase in the amounts of bone fluoride. The variation in the HOMA-IR values could be the consequence of variation in the sensitivity of tissues to insulin or decrease in plasma fluoride levels due to bone fluoride intake. These findings indicate that the performance of daily physical activity could reduce the negative effects of the chronic ingestion of NaF on glucose homeostasis.

Avaliação da influência do fluoreto no reparo ósseo em alvéolo dental de ratos: análise morfométrica e perfil de atividade das MMP-2 e 9 / Evaluation of the fluoride influence in alveolar bone repair in rats: morphometric analysis and MMP-2 activity

O flúor (F), na forma de fluoreto de sódio (NaF), é um elemento presente no cotidiano de quase a totalidade da população brasileira, sendo usado na água de abastecimento (Brasil) e também como terapêutico para osteoporose (comumente na Europa). Assim sendo, é importante o entendimento do efeito do flúor no reparo ósseo. Neste estudo foram utilizados 4 grupos com ratos Wistar de 80 dias (n=200), os quais receberam água de beber contendo 5, 15 e 50 ppm de flúor e água deionizada (grupo controle) durante todo experimento. Esses animais tiveram o incisivo superior direito extraído. Os animais foram eutanasiados O hora, 7, 14, 21 e 30 dias após a extração, sendo coletado sangue (análise da concentração de flúor), a região do alvéolo dental para análise microscópica (análise histológica e morfometria) e extração de proteínas referentes ao reparo ósseo (metaloproteinases de matriz - MMPs 2 e 9). A análise de concentração de flúor no plasma sangüíneo mostrou maior presença desse elemento no grupo tratado com 50 ppm de F nos períodos de 21 e 30 dias. A análise histológica detectou osso neoformado em todos os animais após 30 dias, porém o grupo de 50 ppm de F apresentou menor formação óssea que os outros grupos. A análise morfométrica mostrou um aumento na densidade de volume de osso neoformado, entre 7 e 30 dias, nos grupos controle, 5, 15 e 50 ppm de F, com concomitante diminuição na densidade de volume de tecido conjuntivo e coágulo sangüíneo. A atividade da MMP-2 foi mais acentuada no período inicial, enquanto a MMP-9 teve maior atividade no período final. Concluiu-se que o F, em altas concentrações, pode retardar o reparo alveolar diminuindo a formação de novo tecido ósseo, associado a um atraso na remissão do coágulo.

The fluorine (F), in the sodium fluoride (NaF) form, is an element daily present for most people, being used in water supply (Brazil) and also as therapy for osteoporosis (common in Europe). In such case it is important the understanding of the effect of fluoride in physiologic repair in bone tissue. This study used 4 groups of rats for 80 days (n = 200), which received drinking water containing 5, 15 and 50 ppm of fluoride, and deionized water (control group) throughout experimento These animais had the right upper incisor extracted. The animais were euthanized O hours, 7, 14, 21 and 30 days after extraction, and blood collected (analysis of the concentration of fluorine), the region of the dental alveolus for microscopic exa'mination (histological analysis and morphometry) and extraction of proteins for the bone repair (the matrix metalloproteinases - MMP 2 and 9). The analysis of concentration of fluoride in blood plasma showed greater presence of that element in the group treated with 50 ppm of F in periods of 21 and 30 days. Histological analysis detected neoformed bone in ali animais after 30 days, but the group of 50 ppm F showed lower bone formation than the other groups. Morphometric analysis showed an increase in the volume density of neoformed bone, between 7 and 30 days in control groups, 5, 15 and 50 ppm F, with a concomitant decrease in the volume density of connective tissue and blood dot. The activity of MMP-2 was more pronounced in the initial period, while MMP-9 had higher activity in the 30 days. It was concluded that the F, in high concentrations, may delay the tooth socket repair reducing the formation of new bone tissue, associated with a delay in remission of blood clot.

Absence of DNA damage in multiple organs (blood, liver, kidney, thyroid gland and urinary bladder) after acute fluoride exposure in rats.

Fluoride has been widely used in dentistry as a caries prophylactic agent. However, there has been some speculation that excess fluoride could cause an impact on genome integrity. In the current study, the potential DNA damage associated with exposure to fluoride was assessed in cells of blood, liver, kidney, thyroid gland and urinary bladder by the single cell gel (comet) assay. Male Wistar rats aging 75 days were distributed into seven groups: Groups 1 (control), 2, 3, 4, 5, 6 and 7 received 0 (deionized water), 10, 20, 40, 60, 80 and 100 mgF/Kg body weight from sodium fluoride (NaF), respectively, by gastrogavage. These groups were killed at 2 h after the administration of the fluoride doses. The level of DNA strand breaks did not increase in all organs evaluated and at all doses of NaF tested, as depicted by the mean tail moment. Taken together, our results suggest that oral exposure to NaF did not result in systemic genotoxic effect in multiple organs related to fluoride toxicity. Since DNA damage is an important step in events leading to carcinogenesis, this study represents a relevant contribution to the correct evaluation of the potential health risk associated with chemical exposure.