Abstract
Intact mouse thyroid glands were used to measure the formation of cyclic [3H]AMP from [3H]adenine, and the release of thyroidal iodine. These two parameters of thyroid activity responded to similar concentrations of thyroid-stimulating hormone (TSH). Both were stimulated by prostaglandin E1, although the response was always very much less than to TSH. Both were inhibited by NaF, which appeared to have a toxic effect on the gland. The response to TSH was in each case reduced by lithium, suggesting that the antithyroid effect of Li+ is associated with a direct action on adenyl cyclase; however, Li+ also reduced thyroidal hormone secretion induced by dibutyryl cyclic AMP and may therefore have a second site of action. In general, the effects of these agents on cyclic [3H]AMP formation correlated well with their effects on thyroidal iodine release. The results support the hypothesis that the activation of adenyl cyclase is closely associated with, and precedes, thyroid hormone secretion.
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Inhibition of thyroid secretion by sodium fluoride in vitro
NaF mimicked the activation by thyrotropin of iodide binding to proteins and of glucose C-r oxidation but not the accumulation of intracellular colloid droplets or the stimulation of secretion in dog thyroid slices in vitro. On the contrary, NaF inhibited the two latter thyrotropin effects. The inhibitory action of F-
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The effects and underlying mechanism of excessive iodide on excessive fluoride-induced thyroid cytotoxicity
In many regions, excessive fluoride and excessive iodide coexist in groundwater, which may lead to biphasic hazards to human thyroid. To explore fluoride-induced thyroid cytotoxicity and the mechanism underlying the effects of excessive iodide on fluoride-induced cytotoxicity, a thyroid cell line (Nthy-ori 3-1) was exposed to excessive fluoride and/or excessive
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Fluoride-induced thyroid cell apoptosis
In addition to causing skeletal and dental fluorosis, fluoride (F) in drinking water may damage other organs including the thyroid. The objective of this study was to explore the toxicity of F on immortalized human normal thyroid cells (Nthy-ori 3-1) exposed to 0, 0.1, 1, and 3 mmol/L of sodium
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[Chronic effects of fluorides on the pituitary-thyroid system in industrial workers].
Radioimmunologic study of thyrotropin and thyroid hormones in the blood of those engaged in fluorine production showed moderate functional changes of the hypophysis-thyroid gland system, not accompanied by clinical manifestations of hypo- or hyperthyreosis and caused by disorders of the regulatory chain and fluorine impact on thyroid hormones' metabolism at
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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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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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NRC (2006): Fluoride's Impact on the Thyroid Gland
Several lines of information indicate an effect of fluoride exposure on thyroid function. It is difficult to predict exactly what effects on thyroid function are likely at what concentration of fluoride exposure and under what circumstances.
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Fluorine in the Aetiology of Endemic Goitre
The distribution of endemic goitre in the Punjab and in England is related to the geological distribution of fluorine and to the distribution of human dental fluorosis (mottled enamel). Inquiry showed the presence of dental fluorosis among school-children in two areas of Somerset where two previous observers had recorded a high incidence of goitre, and the absence of dental fluorosis in an adjoining area selected as control where endemic goitre was absent.
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Fluoride Exposure Aggravates the Impact of Iodine Deficiency
A consistent body of animal and human research shows that fluoride exposure worsens the impact of an iodine deficiency. Iodine is the basic building block of the T3 and T4 hormones and thus an adequate iodine intake is essential for the proper functioning of the thyroid gland. When iodine intake is inadequate during infancy and
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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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