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.

• Related Studies :

  • 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-

  • Taurine ameliorates renal oxidative damage and thyroid dysfunction in rats chronically exposed to fluoride

    Excessive exposure to fluoride poses several detrimental effects to human health particularly the kidney which is a major organ involved in its elimination from the body. The influence of taurine on fluoride-induced renal toxicity was investigated in a co-exposure paradigm for 45 days using five groups of eight rats each. Group I rats received

  • Ameliorative effect of resveratrol against fluoride-induced alteration of thyroid function in male wistar rats

    Resveratrol (3,4,5-trihydroxystilbene), a polyphenol and well-known natural antioxidant has been evaluated for its protective effect against fluoride-induced metabolic dysfunctions in rat thyroid gland. Fluoride, the most abundant anions present in groundwater throughout the world, creates a major problem in safe drinking water and causes metabolic, structural, and functional injuries in

  • 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

  • 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

• Related FAN Content :

  • 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

  • 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.

  • Fluoride & Goiter

    Goitre (aka goiter) is an enlargement of the thyroid gland that in some cases can produce visible swelling in the neck. The main cause of goitre is iodine deficiency. Goitre can also be caused by other things, including hypothyroidism and substances that cause goitre (goitrogens). Since as far back as the

  • 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.

  • 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.