Fluoride = TSH © Copyright 1996-2016 PFPC
During the late 1960s and throughout the 1970s many studies were conducted to investigate the effects of TSH on adenyl cyclase.
At this time it was commonly held that polypeptide hormones such as TSH produced many of their cellular effects by stimulating adenyl cyclase, thus increasing intracellular cAMP levels (Wolff & Jones, 1971; Wienand and Kohn, 1975). cAMP was, in turn, thought to exert its effects by activating protein kinases.
Fluoride had been found to be an activator of adenyl cyclase in many tissues, and investigators now used fluoride to learn more about TSH. These studies brought firm evidence that fluoride not only acted like TSH, but fluoride-stimulated cyclase activity was found to be 2 to 5 times higher than the optimal TSH stimulation.
Like TSH, at low levels fluoride stimulated adenyl cyclase activity, while at higher doses it inhibited cyclase activation (Wolff & Jones, 1971; Wienand and Kohn, 1975; Jenq et al, 1993; Clark & Gerend, 1985).
The graphs below were extracted from the study done by Wolff and Jones (1971), documenting the largely identical effects of fluoride and TSH on adenyl cyclase:
Adenyl Cyclase - A membrane-bound enzyme that converts adenosine monophosphate to cyclic adenosine monophosphate (cAMP), an intracellular second messenger.
TSH - Short for thyroid-stimulating-hormone, also called thyrotropin, secreted by the anterior pituitary gland; activates adenyl cyclase (cAMP production) in thyroid cells leading to production and release of the thyroid hormones (T4 and T3). The TSH-receptor is the only G-protein-coupled receptor known able to activate all G protein families, an activity directly mimicked by fluoride.
Selected studies using fluoride as TSH analogue:
Ahn CS, Rosenberg IN - "Iodine metabolism in thyroid slices: effects of TSH, dibutyryl cyclic 3',5'-AMP, NaF and prostaglandin E-1" Endocrinology 86(2):396-405 (1970)
Bech K, Feldt-Rasmussen U, Madsen SN - "Influence of thyroglobulin on basal and stimulated human thyroid adenylate cyclase activity" J Clin Endocrinol Metab 53(2):264-9 (1981)
Bech K, Madsen SN - "Human thyroid adenylate cyclase in non-toxic goitre: sensitivity to TSH, fluoride and thyroid stimulating immunoglobulins" Clin Endocrinol (Oxf) 8(6):457-66 (1978)
Bidey SB, Marshall MJ, Ekins RP - Cyclic AMP release from normal human thyroid slices in response to thyrotrophin Acta Endocrinol, 95: 335 - 340 (1980)
Birnbaumer L, Rodbell A - "Adenyl Cyclase in Fat Cells. II. HORMONE RECEPTORS" J Biol Chem 244: 3477-3482 (1969)
Burke G - "Comparison of thyrotropin and sodium fluoride effects on thyroid
adenyl cyclase" Endocrinology 86(2):346-52 (1970)
Burke G -"Effects of thyrotropin, sodium fluoride and ions on thyroid slice
metabolism" Metabolism 19(1):35-42 (1970)
Carayon P, Guibout M, Lissitzky S - "Thyrotropin receptor-adenylate cyclase system in plasma membranes from normal and diseased human thyroid glands" J Endocrinol Invest 1(4):321-8 (1978)
Clark OH, Gerend PL - "Thyrotropin regulation of adenylate cyclase activity in human thyroid neoplasms" Surgery 97(5):539-46 (1985)
Codaccioni JL, Carayon P, Michel-Bechet M, Foucault F, Lefort G, Pierron H - "Congenital hypothyroidism associated with thyrotropin unresponsiveness and thyroid cell membrane alterations" J Clin Endocrinol Metab 50(5):932-7 (1980)
Cohen-Luria R, Sigler L, Rimon G - "Biphasic effect of sodium fluoride and guanyl nucleotides on binding to prostaglandin E2 receptors in rat epididymal adipocyte membranes" Cell Signal 1(6):561-8 (1989)
Corvilain B, Laurent E, Lecomte M, Vansande J, Dumont JE - "Role of the cyclic adenosine 3',5'-monophosphate and the phosphatidylinositol-Ca2+ cascades in mediating the effects of thyrotropin and iodide on hormone synthesis and secretion in human thyroid slices" J Clin Endocrinol Metab 79(1):152-9 (1994)
DeEds F, Wilson RH, Cutting WC - "Thyrotropic hormone and fluorine activity" Endocrinology 26(6):1053-1056 (1940)
Delemer B, Dib K, Saunier B, Haye B, Jacquemin C, Correze C - "Alteration of the functional activity of Gs protein in thyrotropin-desensitized pig thyroid cells" Mol Cell Endocrinol 75(2):123-31 (1991)
Field JB, Bloom G, Kerins ME, Chayoth R, Zor U - "Activation of protein kinase in thyroid slices by thyroid-stimulating hormone" J Biol Chem
Fradkin JE, Cook GH, Kilhoffer MC, Wolff J - "Forskolin stimulation of thyroid adenylate cyclase and cyclic 3',5'-adenosine monophosphate accumulation" Endocrinology 111(3):849-56 (1982)
Giraud A, Siffroi S, Lanet J, Franc JL - "Binding and internalization of thyroglobulin: selectivity, pH dependence, and lack of tissue specificity" Endocrinology 138(6):2325-32 (1997)
Goldhammer A, Wolff J - "Interactions of fluoride and guanine nucleotides with thyroid adenylate cyclase" Biochim Biophys Acta 701(2):192-9 (1982)
Holmes SD, Titus G, Chou M, Field JB - "Effects of thyrotropin and cholera toxin on the thyroidal adenylate cyclase-adenosine 3',5'-monophosphate system" Endocrinology 107(6):2076-81 (1980)
Jenq SF, Jap TS, Hsieh MS, Chiang H - "The characterization of adenyl cyclase activity in FRTL-5 cell line" Chung Hua I Hsueh Tsa Chih (Taipei) (Journal of the Chinese Medical Association) 51(3):159-65 (1993)
Juvenal GJ, Kleiman de Pisarev DL, Crenovich L, Pisarev MA. - "Role of
neurotransmitters, prostaglandins and glucose on precursor incorporation into the RNA of thyroid slices" Acta Endocrinol (Copenh) 87(4):776-85 (1978)
Kalderon AE, Sheth V - "Secretion and adenylate cyclase in thyroid nodules" Arch Pathol Lab Med 102(7):381-86 (1978)
Kendall-Taylor P - "Comparison of the effects of various agents on thyroidal adenyl cyclase activity with their effects on thyroid hormone release" J Endocrinol 54(1):137-45 (1972)
Lakey T, Mac Neil S, Humphries H, Walker SW, Munro DS, Tomlinson S - "Calcium and calmodulin in the regulation of human thyroid adenylate cyclase activity" Biochem J 225(3):581-9 (1985)
Laugwitz KL, Allgeier A, Offermanns S, Spicher K, Van Sande J, Dumont JE, Schultz G - "The human thyrotropin receptor: a heptahelical receptor capable of
stimulating members of all four G protein families" Proc Natl Acad Sci U S A 93(1):116-20 (1996)
Mallet E, Carayon P, Amr S, Brunelle P, Ducastelle T, Basuyau JP, de Menibus CH - "Coupling defect of thyrotropin receptor and adenylate cyclase in a
pseudohypoparathyroid patient" J Clin Endocrinol Metab
Mizukami Y, Matsubara F, Matsukawa S - "Localization of adenylate cyclase and 5'-nucleotidase activities in human thyroid follicular cells" Histochemistry 74(1):9-19 (1982)
Moore WV, Wolff J - "Thyroid-stimulating hormone binding to beef thyroid membranes. Relation to adenylate cyclase activity" J Biol Chem
Nagai Y, Hosoya T - "Properties of the Na+, K+-stimulated adenosine triphosphatase system associated with the plasma membrane of pig thyroid glands" J Biochem (Tokyo) 81(3):721-7 (1977)
Orgiazzi J, Chopra IJ, Solomon DH, Williams DE - "Comparison of the effect of TSH and fluoride on the adenylate cyclase activity of cold thyroid nodules" Ann Endocrinol (Paris) 37(2):107-8 (1976)
Pastan I, Macchia V, Katzen R - "Effect of fluoride on the metabolic activity of thyroid slices" Endocrinology 83(1):157-60 (1968)
Raspé E, Roger PP, Dumont JE - "Carbamylcholine, TRH, PGF2 alpha and fluoride enhance free intracellular Ca++ and Ca++ translocation in dog thyroid cells" Biochem Biophys Res Commun 141(2):569-77 (1986)
Rodesch F, Neve P, Willems C, Dumont JE - "Stimulation of thyroid metabolism by thyrotropin, cyclic 3':5'-AMP, dibutyryl cyclic 3':5'-AMP and prostaglandin E1" Eur J Biochem 8(1):26-32 (1969)
Shuman SJ, Zor U, Chayoth R, Field JB - " Exposure of thyroid slices to
thyroid-stimulating hormone induces refractoriness of the cyclic AMP system tosubsequent hormone stimulation" J Clin Invest 57(5):1132-41 (1976)
Suzuki S, Widnell C, Field JB - "Preparation and characterization of subfractions of bovine thyroid plasma membranes" J Biol Chem
Thode J, Børresen T, Beck K, Madsen SN -"Effect of furosemide on parathyroid hormone stimulated guinea pig renal adenylate cyclase and thyrotrophin and fluoride stimulated human thyroid adenylate cyclase" Acta Pharmacol Toxicol (Copenh) 49(4):285-9 (1981)
Toccafondi RS, Rotella CM, Tanini A, Fani P, Arcangeli P - "Thyrotrophin-responsive adenylate cyclase activity in thyroid toxic adenoma" Acta Endocrinol (Copenh) 92(4):658-68 (1979)
Tomura H, Itoh H, Sho K, Sato K, Nagao M, Ui M, Kondo Y, Okajima F - "Betagamma subunits of pertussis toxin-sensitive G proteins mediate A1 adenosine receptor agonist-induced activation of phospholipase C in collaboration with thyrotropin. A novel stimulatory mechanism through the cross-talk of two types of receptors" J Biol Chem 272(37):23130-7 (1997)
Totsuka Y, Nielsen TB, Field JB - "Effect of thyrotropin-induced desensitization of bovine thyroid adenylate cyclase on the nucleotide regulatory protein" Endocrinology 113(3):1088-95 (1983)
Totsuka Y, Nielsen TB, Field JB - "Roles of GTP and GDP in the regulation of the thyroid adenylate cyclase system" Biochim Biophys Acta 718
Walinder O, Karlsson FA, Dahlberg PA - "Adenyl cyclase activity in human thyroid plasma membranes from normal human thyroid tissue and thyroid adenomas" Acta Endocrinol (Copenh) 92(1):95-104 (1979)
Willems C, Berberof-van Sande J, Dumont JE - "Inhibition of thyroid secretion by sodium fluoride in vitro" Biochim Biophys Acta 264(1):197-204 (1972)
Winand RJ, Kohn LD - "Stimulation of adenylate cyclase activity in retro-orbital tissue membranes by thyrotropin and an exophthalmogenic factor derived from thyrotropin" J Biol Chem 250: 6522 - 6526 (1975)
"As with thyroid plasma membranes (12), fluoride stimulated cyclase activity in retro-orbital tissue plasma membranes is about 2 to 3 times higher than optimal TSH...stimulable cyclase activity. Half-maximal stimulation occurred at 4mM F- under these assay conditions, maximal stimulation was between 8 and 15 mM, and inhibition occurred at greater than 15 mM F - concentrations."
Wolff J, Jones AB - "The Purification of Bovine Thyroid Plasma Membranes and the Properties of Membrane-bound Adenyl Cyclase" J Biol Chem 246:3939 - 3947 (1971)
"Like other mammalian adenyl cyclases, the thyroid membrane preparation was stimulated by F-. Half-maximal stimulation was attained at 2 to 3 mM -under current assay conditions. With 10 mM F- cyclase activity was stimulated 8 to 35 times the basal activity in various preparations and from 2 to 5 times the activity produced by 200 munits of TSH."
Wolff J, Cook GH - "Activation of thyroid membrane adenylate cyclase by purine nucleotides" J Biol Chem 10;248(1):350-5 (1973)
Wolff J, Cook GH - "Charge effects in the activation of adenylate cyclase" J Biol Chem 10;250(17):6897-903 (1975)
Yamashita K, Field JB - "Elevation of cyclic guanosine 3',5'-monophosphate levels in dog thyroid slices caused by acetylcholine and sodium
J Biol Chem 247(21):7062-6 (1972)
Zor U, Kaneko T, Lowe IP, Bloom G, Field JB - "Effect of thyroid-stimulating hormone and prostaglandins on thyroid adenyl cyclase activation and cyclic adenosine 3',5',-monophosphate" J Biol Chem 244(19):5189-95 (1969)
As research continued, numerous investigations showed that - although fluoride was able to activate adenyl cyclase in homogenates in thyroid slices - it did not increase cyclic AMP levels as expected (i.e Zor et al, 1970), yet it produced the same effects as TSH . This finding led researchers to believe that TSH and fluoride effects, although identical, must have been obtained by different mechanisms (i.e Yamashita & Field, 1972).
During the 1980s and 1990s, the discovery of G-proteins and the application of fluoride as the "universal G protein activator" brought much new knowledge to the field of signal transduction. The human TSH receptor was found to be the only known natural universal G-protein activator - able to activate all four G protein families (Laugwitz et al, 1996). It was established that TSH-activation of adenyl cyclase was absolutely dependent on the regulatory nucleotides. (Totsuka et al, 1982).
While many pro-fluoridation organizations and dental groups claim that the amounts of fluoride used in the TSH in-vitro experiments were 100 to 1000 times higher, and "such levels could never be obtained in humans", they fail to realize that these experiments were made in isolated environments - specifically to find out about adenyl cyclase. TSH levels used in those experiments were also much higher than is ever found in humans. In the system, when other nucleotides are present, fluoride will - just like TSH - activate adenyl cyclase at low concentrations, while inhibiting same at higher concentrations. This is time- and tissue-specific. (see Jenq et al., 1993; Cohen-Luria et al.,1989)
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