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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Role of endoplasmic reticulum stress-induced apoptosis in rat thyroid toxicity caused by excess fluoride and/or iodide
Excess fluoride and iodide coexist in drinking water in many regions, but few studies have investigated the single or interactive effects on thyroid in vivo. In our study, Wistar rats were exposed to excess fluoride and/or iodide through drinking water for 2 or 8 months. The structure and function of
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y-Aminobutyric acid ameliorates fluoride-induced hypothyroidism in male kunming mice
AIM: This study evaluated the protective effects of y-aminobutyric acid (GABA), a non-protein amino acid and anti-oxidant, against fluoride-induced hypothyroidism in mice. MAIN METHODS: light microscope sample preparation technique and TEM sample preparation technique were used to assay thyroid microstructure and ultrastructure; enzyme immunoassay method was used to assay hormone and
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Is water fluoridation a hidden cause of obesity? Histological study on thyroid follicular cells of albino rats
Introduction: Fluoride in drinking water is known to exert both beneficial and detrimental effects on health. When consumed in excess, it is known to cause adverse effects including dental fluorosis, hip fracture, bone cancer, lower intelligence, and kidney toxicity plus goiter. Aim: This study was carried out to determine the histological
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Effects of fluoride on the ultrastructure of glandular epithelial cells of human fetuses.
Objective Ultrastructural changes in epithelial cells of livers, adrenal glands, and thyroid glands of human fetuses from a fluorosis-endemic area were observed to provide an experimental basis for investigating the mechanism by which fluoride causes cellular damage. Methods 10 human fetuses in a fluorosis-endemic area were collected, whose mothers all had
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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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Mikhailets (1996): Functional state of thyroid under extended exposure to fluorides
Abnormalities in the thyroid function characterized by a decreased iodine absorption function of the thyroid, a low level T3 syndrome, and a slight increase of the TSH level are observed in cases of chronic fluorine intoxication in the industrial workers.
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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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The Relationship Between Fluoride Exposure & Goitre in South Africa
As a general rule simple goitre, irrespective of the cause, can be very, or fairly, satisfactorily combated by an adequate increase in man's daily iodine intake, except when the enlargement of the gland is due to the ingestion of excessive amounts of fluorine. The only correct solution to fluorine-induced endemic goitre is the removal of this element from the drinking water.
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Fluoride, Water Hardness, and Endemic Goitre
Variations in goitre prevalence were found to correlate closely with the fluoride content (p=0-74; P<0-01) and with the hardness (p=0.77; P<0-01) of the water in each village. The effects of fluoride and water hardness seem to be independent.
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