Abstract
High-fluoride (100 and 200 ppm) water was administered to rats orally to study the fluoride-induced changes on the thyroid hormone status, the histopathology of discrete brain regions, the acetylcholine esterase activity, and the learning and memory abilities in multigeneration rats. Significant decrease in the serum-free thyroxine (FT4) and free triiodothyronine (FT3) levels and decrease in acetylcholine esterase activity in fluoride-treated group were observed. Presence of eosinophilic Purkinje cells, degenerating neurons, decreased granular cells, and vacuolations were noted in discrete brain regions of the fluoride-treated group. In the T-maze experiments, the fluoride-treated group showed poor acquisition and retention and higher latency when compared with the control. The alterations were more profound in the third generation when compared with the first- and second-generation fluoride-treated group. Changes in the thyroid hormone levels in the present study might have imbalanced the oxidant/antioxidant system, which further led to a reduction in learning memory ability. Hence, presence of generational or cumulative effects of fluoride on the development of the offspring when it is ingested continuously through multiple generations is evident from the present study.
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Effects of sub-acute fluoride exposure on discrete regions of rat brain associated with thyroid dysfunction: a comparative study
Objectives: In this present in vivo study, it is intended to examine the effects of fluoride on metabolic functions of four discrete regions of rat brain associated with thyroidal insufficiency. Background: Fluoride contamination in drinking water is a major health issue. Adverse health effects of fluoride include dental and muscle fluorosis,
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Effects of fluoride exposure on thyroid hormone level and intelligence in rats
Objective: To investigate the effects of fluoride exposure on the thyroid hormone level and intelligence in rats and to investigate the biomarkers of intellectual impairment induced by high fluoride exposure. Methods: A total of 24 clean healthy Sprague-Dawley rats were randomly divided into control group (tap water containing 0.344 mg/L fluoride)
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Fluoride-induced developmental disorders and iodine deficiency disorders as examples of developmental disorders due to disturbed thyroid hormone metabolism.
Both exposure to fluoride and iodine deficiency during early development can lead to disturbed thyroid hormone metabolism and produce the same spectrum of developmental disorders including short stature, bone deformities, cognitive impairment, delayed dental eruption, and dental fluorosis. The levels of creatinine-adjusted urinary fluoride experienced by pregnant women in areas
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The relationships between thyroid-stimulating hormone and/or dopamine levels in peripheral blood and IQ in children with different urinary iodine concentrations.
Highlights TSH is not related IQ in children with different urinary iodine concentrations. Dopamine in plasma is unrelated to IQ in children with adequate or excessive iodine. Dopamine has positive correlation with intelligence in iodine deficiency group. The interaction between dopamine in plasma and TSH is not related to
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The effects of high levels of fluoride and iodine on intellectual ability and the metabolism of fluoride and iodine.
The authors carried out a study on the intellectual abilities and fluoride/iodine metabolism of children living in a high fluoride-high iodine area. Among the results: the percentage of the general population living in this fluoride/iodine-contaminated region that suffered from goiter (clinical thyroid enlargement) was 3.8%, the rate of children already showing some thyroid
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Fluoride's Impact on Thyroid Hormones
Up through the 1950s, doctors in Europe and South America prescribed fluoride for this purpose in patients with hyperthyroidism. (Merck Index 1968). Fluoride was selected as a thyroid suppressant based on findings dating back to the mid-19th century that fluoride is a goitrogen (a substance that can cause goiter). When used as
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Fluoride Aggravates Thyroid Damage Caused by Excess Iodine Intake
Chinese researchers have found that the combination of excess fluoride with excess iodine caused greater reductions in IQ, or greater increases in goitre than either scenario by itself.
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Fluoride's Effect on Fetal Brain
The human placenta does not prevent the passage of fluoride from a pregnant mother's bloodstream to the fetus. As a result, a fetus can be harmed by fluoride ingested pregnancy. Based on research from China, the fetal brain is one of the organs susceptible to fluoride poisoning. As highlighted by the excerpts
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Fluoride's Direct Effects on Brain: Animal Studies
The possibility that fluoride ingestion may impair intelligence and other indices of neurological function is supported by a vast body of animal research, including over 40 studies that have investigated fluoride's effects on brain quality in animals. As discussed by the National Research Council, the studies have consistently demonstrated that fluoride, at widely varying concentrations, is toxic to the brain.
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Is fluoride-induced hyperthyroidism a cause of psychosis among East African immigrants to Scandinavia?
When people with a compensated fluoride-induced hypothyroidism move to a low-fluoride area, the fluoride-induced inhibition of the production of thyroid hormones ceases. In Scandinavia, the dietary intake of iodine is usually quite high due to iodized table salt and easy access to marine fish. Under these conditions, the elevated capacity for production of thyroid hormones may result in hyperthyroidism.
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