Thyroid-Stimulating Activity and Chorionic Gonadotropin

Nisula, Bruce C.; Ketelslegers, Jean‐Marie

doi:10.1172/jci107785

Cited by 85 publications

(15 citation statements)

References 32 publications

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“…This 'hyperthyroidism with suppressed TSH' is known with patients suffering Graves' disease, hyperemesis gravidarum, and trophoblastic diseases. The pathogenic agents causing these diseases have been identified: thyroid-stimulating antibodies in Graves' disease, excess levels of human chorionic gonadotropin (hCG) and in hyperemesis gravidarum (Lao et al 1988, Rodien et al 1998 and in trophoblastic diseases (Nisula & -Ketelslegers 1974, Nisula & Taliadouros 1980, Hoermann et al 1994. Recently, two cases of goitrous euthyroid patients presenting low TSH have been reported (Ikekubo et al 2005).…”

Section: Discussionmentioning

confidence: 99%

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

Nagasaki

Wang

Jackson

et al. 2006

Journal of Molecular Endocrinology

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Two glycoprotein hormone subunits, (glycoprotein hormone a2-subunit GPA2) and (glycoprotein hormone b5-subunit GPB5) have been recently discovered which, when expressed in vitro, heterodimerize to form a new hormone called thyrostimulin. Thyrostimulin activates the thyroid-stimulating hormone receptor (TSHR) and has thyrotropic activity. Immunological studies have indicated that both subunits co-localize in pituitary cells. To explore the function of thyrostimulin in the rat, we have cloned rat GPA2 and GPB5, reconstituted the heterodimers in vitro, and confirmed that rat thyrostimulin activates TSHR with an affinity similar to that of TSH. In situ hybridization of the pituitary showed that while GPA2 is expressed in the anterior lobe, GPB5 is not detected in any of the lobes. A quantitative analysis showed that the co-localization of GPA2 and GPB5 is restricted in the rat to the eye and the testis. We found that GPB5 can be detected in the pituitary by quantitative-PCR, but at extremely low levels, 2000-fold lower than TSH b-subunit (GPBtsh). Furthermore, the levels of GPB5 remain constant during the estrus cycle, while those of GPA2 vary. Finally, we found that none of the thyrostimulin subunits was induced by TRH in pituitary cell culture. These data point at the thyrostimulin system as being functionally different to the TSH system.

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Section: Discussionmentioning

confidence: 99%

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

Nagasaki

Wang

Jackson

et al. 2006

Journal of Molecular Endocrinology

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“…Abundant reports now exist confirming the intrinsic thyroid-stimulating activity of the hCG molecule (1,21,22). hCG has activity in the mouse TSH bioassay (1,21,22), increases cAMP in human thyroid tissue (23), and displaces labeled TSH from the thyroid receptor in human and bovine thyroid tissue (23)(24)(25).…”

Section: Discussionmentioning

confidence: 99%

Comparison of Thyroid Stimulators and Thyroid Hormone Concentrations in the Sera of Pregnant Women*

Harada

Hershman

Reed

et al. 1979

The Journal of Clinical Endocrinology & Metabolism

211

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To clarify the role of various thyroid stimulators in normal human pregnancy, we measured serum TSH, chorionic TSH (hCT), hCG, bioassayable thyroid-stimulating activity, T4, T3, T3 uptake, free T4 and free T3 indexes, free T4, and free T3 by dialysis in 339 serum samples from pregnant women at various intervals of pregnancy and in 40 normal female controls. Serum T4 and T3 and free T4 and free T3 indexes were significantly elevated throughout pregnancy in comparison with controls. Free T4 concentration was elevated after 10 weeks of pregnancy and free T3 concentration was elevated at 13--20 weeks. Bioassayable thyroid-stimulating activity was elevated from 9--16 weeks when serum hCG concentrations were highest. Serum TSH levels were significantly lower at 9--12 weeks compared with the rest of pregnancy. hCT was detected in only 35% of sera tested; the mean detectable value was 0.60 +/- 0.04 (SE) microU/ml; only 15% of the detectable values exceeded 1 microU/ml. The level of hCG correlated with bioassayable thyroid-stimulating activity (P less than 0.01). The data indicate that hCT is not a significant thyroid stimulator. We propose that hCG, as a weak thyroid stimulator, causes a modest rise in free thyroid hormone levels early in pregnancy which in turn causes a modest reduction in pituitary TSH secretion.

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“…In mammals thyroidgonadotropin hormone interaction is well documented (e.g. Nisula & Ketelsleger 1974, Nisula et al 1974, Amir et al 1977, Aranda et al 1976). Studies in a number of teleostean species have shown an apparent thyrotropic effect of mammalian or piscine gonadotropin preparations (Ahsan & Hoar 1963, Fontaine 1969b, Donaldson & McBride 1974, Grau & Stetson 1977a, Miline & Leatherland 1979, 1980b.…”

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confidence: 99%

Environmental physiology of the teleostean thyroid gland: a review

Leatherland

1982

Environ Biol Fish

140

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SynopsisRecent studies of thyroid hormone function are reviewed as they relate to the environmental physiology of teleost fish. In addition, reports dealing with the apparent interdependence of thyroid gland function with that of other endocrine glands are discussed with emphasis on the interrelated endocrine response associated with changing physiological status of teleosts.Seasonal changes in thyroid gland activity are described in several species. Although seasonal alterations in apparent thyroid status are concomitant with changes in ambient temperature, photoperiod and/or gonadal status, their biological significance is not fully understood and direct relationships are for the most part, not proven. Similarly, most reports of thyroid involvement in gonadal development or maturation are based on indirect evidence of the relationship. The exception to this is a study in immature or hypophysectomized goldfish in which thyroxine (T4) was shown to promote ovarian development and maturation, possibly acting collateralistically or synergistically with gonadotropin. Even in this study it is not clear whether the Td effect is a direct action on the ovarian tissue or an indirect action via the regulation of metabolites necessary for gonad metabolism. Integumentary silvering and retinal porphyropsin formation in salmonids are stimulated by administration of T4 or thyroid extracts. Administration of T4 or triiodothyronine (T3) enhances skeletal and somatic growth in some teleostean species, although the effect on somatic growth is most pronounced when these hormones act synergistically with somatotropin (STH) or androgens. The growth-promoting effects of T4 and T3 may be linked to their apparent involvement in lipid, carbohydrate, protein and vitamin metabolism. Alterations in apparent thyroid activity concomitant with changes in ambient temperature have been reported (for example correlated with seasonal ambient thermal changes), although there are marked contradictions in data presented by different investigators. Reported temperature-related effects on thyroid function are probably secondary responses of thyroid metabolism to altered temperatures. Evidence of a direct rate of thyroid hormones in the regulation of migration (and associated behavioural modifications), salmonid smoltification, oxygen consumption, and osmotic or ionic regulation although highly suggestive in a number of areas is inconclusive and requires further critical experimental evaluation.The pituitary control (by thyrotropin) of thyroid secretion of T4 is convincingly shown in several teleosts, and Receivrd 26.6.1980 Accepted 6.12.1980 0 Dr W. Junk Publishers, The Hague. Printed in The Netherlands. 0378.1909/82/0071-0083 $03.4083 evidence of an inhibitory hypothalamic control of thyrotrop activity is highly suggestive in some species. A thyrotropic effect of somatotropin preparations is well established in several teleostean species; the effect does not appear to be related to contamination of the somatotropin preparations with thyrotropin, and ma...

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Thyroid-Stimulating Activity and Chorionic Gonadotropin

Cited by 85 publications

References 32 publications

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

Comparison of Thyroid Stimulators and Thyroid Hormone Concentrations in the Sera of Pregnant Women*

Environmental physiology of the teleostean thyroid gland: a review

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