Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q17RS7 (Gen)
 130,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Long-term administration of L-thyroxine (T4) in the wax bill (lal munia) inhibited the current gonad development cycle, and the increase in gonadal volume in the second cycle was suppressed only by higher concentrations. Gonadal inhibition by high but not by low doses of L-T4 was associated with a failure in the development of LH-dependent pigmented nuptial plumage. This suggests that L-T4 depresses FSH secretion more readily than LH secretion. The results indicate that the effects of L-T4 administration on the body weight cycle depends upon the physiological and/or gonadal status of the bird at the start of the experiment and that the juvenile hypothalamo-hypophysial-gonadal axis is more sensitive to L-T4 than that of the adult birds. The bill color, like plumage pigmentation, appears to be LH controlled. It is suggested that while thyroid hormone, acting by way of the hypothalamo-hypophysial complex and/or by direct action on the feather papillae, modulates the annual cycles of plumage pigmentation, bill color, gonad development, and body weight of lal munia, the finch has an endogenous mechanism which enables it to adapt to chronic hyperthyroidism in such a way that breeding occurs at the normal time of the year.
Gen Comp Endocrinol 1984 Jul
PMID:Thyroid and annual gonad development, body weight, plumage pigmentation, and bill color cycles of lal munia, Estrilda amandava. 674 30

To elucidate the environmental factors and endocrine mechanisms which are responsible for inducing neoteny in the salamander Hynobius retardatus, the effect of temperature on the growth and metamorphosis of this amphibian, as well as the actions of thyroid hormone and prolactin at low temperature, were studied. (1) The metamorphosis of larvae cultivated at 10 degrees was significantly delayed compared with that of larvae cultivated at 22 degrees, but the metamorphosis was eventually completed. At 4 degrees, metamorphosis never occurred, even after 2 years. (2) Exogenously administered thyroid hormone accelerated metamorphosis at 10 degrees or 22 degrees, but was ineffective in larvae kept at 4 degrees, whether administered by injection or immersion. (3) If a higher concentration of thyroid hormone was given by a single injection to larvae cultured at 4 degrees, an appreciable acceleration of metamorphosis was observed after transferring the larvae to 22 degrees. (4) Unlike thyroid hormone, prolactin promoted growth at 4 degrees.
Gen Comp Endocrinol 1983 Jan
PMID:The effect of temperature on the action of thyroid hormone and prolactin in larvae of the salamander Hynobius retardatus. 682 44

Plasma levels of thyroxine (T4) and triiodothyronine (T3) were measured by radioimmunoassay in intact Pacific lamprey (Entosphenus tridentatus) undergoing the period of natural fasting and in Pacific hagfish (Eptatretus stouti) maintained unfed in the laboratory. Plasma T3 levels in both lamprey and hagfish were always severalfold lower than T4 levels. The influence of thyroid hormones on glycemic level was studied following intraperitoneal injection of T4 or T3 (13-20 micrograms/100 g body wt), as well as after implantation of sealed Silastic capsules containing the goitrogen, 6-propylthiouracil (6-PTU), or after intraperitoneal injections of an antithyroglobulin serum (ATgS) exhibiting both anti-T4 and anti-T3 activities. Measured plasma T4 and T3 levels after hormonal injection were extremely high and could be considered pharmacological. The 6-PTU treatment decreased plasma levels of both T4 and T3 within several weeks. The glycemic levels in lampreys and hagfish after thyroid hormone treatment were lower than in control animals, whereas in animals treated with either 6-PTU or ATgS, hyperglycemic levels prevailed. It is concluded that thyroid hormones, possibly acting with other hormones, may participate in the maintenance of glycemic levels in cyclostomes and that their action is to reduce glycemic levels.
Gen Comp Endocrinol 1983 Jan
PMID:Plasma thyroid hormones in cyclostomes: do they have a role in regulation of glycemic levels? 682 52

Injections of adult Fundulus heteroclitus with 0.2 IU of oTSH over 4 days caused an increase in serum T4, with no effect on serum T3. Administration of 12 IU of oPRL in conjunction with the same dosage of TSH prevented the TSH-induced rise in T4, without affecting serum T3 levels. The failure of TSH to cause T4 levels to rise in the presence of PRL may result from either inhibition of release or acceleration of metabolic clearance of T4. We therefore conducted three experiments to examine potential effects of PRL on the kinetics of peripheral clearance of thyroid hormones. 125I T4 was cleared from serum in a biphasic pattern that was unaltered by PRL. Clearance of labeled T3 followed a similar pattern that was also not influenced by PRL treatment. Generation of labeled T3 by deiodination of a dose of 125I T4 was quantified over a 24-h period. Again, PRL-treated fish showed no significant differences. Since PRL is without effects on thyroid hormone clearance patterns or deiodination rate, we conclude that PRL prevents TSH-induced increases in serum T4 in this species by directly affecting thyroid function.
Gen Comp Endocrinol 1983 May
PMID:Prolactin--thyroid interaction in Fundulus heteroclitus. 686 66

Electron microscopical observations were made on the thyrotrophic (TSH) cells during the monthly cycle of oocyte development and pregnancy in female sailfin mollies. Parallel light microscopic studies were made on the thyroid gland. By morphological criteria, TSH secretion and thyroid activity run in parallel, and the findings indicate that TSH secretion and thyroid hormone output are higher during vitellogenic oocyte growth than during earlier oocyte development and during pregnancy. Measurements of TSH cell area and nuclear area and of thyroid epithelial cell height confirm this pattern. The results are discussed in the light of what is known of thyroid hormone involvement in teleostean ovarian physiology.
Gen Comp Endocrinol 1983 Jul
PMID:Ultrastructural changes in the adenohypophysis during the ovarian cycle of the viviparous teleost Poecilia latipinna. II. The thyrotrophic cells and the thyroid gland. 688 59

Sublethal doses of potassium thiocyanate (KSCN), an iodide competitor, depressed thyroidal radioiodide uptake of fed laboratory rainbow trout at 11 degrees, but did not depress either plasma levels of T4 (L-thyroxine) and T3 (triiodo-L-thyronine) or radioiodide incorporation into plasma iodothyronines. Furthermore, plasma T4 levels of KSCN-treated trout increased to levels comparable to those of control trout in response to bovine TSH. The apparent inability of KSCN to inhibit thyroid hormone synthesis and release may be due to non-carrier-mediated iodide diffusion into the thyroid from the high iodide concentration normally found in plasma of freshwater salmonids. In conclusion, KSCN is not a practical inhibitor of thyroid hormone release in laboratory trout, and thyroid radioiodide uptake is a highly misleading index of thyroidal status.
Gen Comp Endocrinol 1983 Jul
PMID:Influence of potassium thiocyanate on thyroid function of rainbow trout, Salmo gairdneri. 688 60

1. The purpose of this study was to examine the possibility that the cellular action of amiodarone is mediated by inhibition of thyroid hormone regulatory functions within the myocardial cell. We measured the rate of cell beating and the activity of Na-K-ATPase in cultured neonatal rat heart myocytes. 2. Amiodarone (0.25 and 1 microgram/ml) reduced beating rate up to 75% within 20 min, and Na-K-ATPase activity up to 40% within 2 hr. No toxic effects were detected in the treated cells. 3. The inhibitory actions of amiodarone on beating rate and Na-K-ATPase activity were the same in myocytes grown in the presence or absence of 3-iodothyronine (T3, 5 nM). 4. These data indicate that amiodarone affects beating rate and Na-K-ATPase activity independently of thyroid hormone. It is suggested that interference of amiodarone with thyroid hormone action is not the only mechanism by which this drug modulates some functions of the myocardial cell.
Gen Pharmacol 1995 Mar
PMID:Effects of amiodarone on beating rate and Na-K-ATPase activity in cultured neonatal rat heart myocytes. 759 75

Daily variations of pineal and plasma melatonin and plasma thyroid hormones were measured in harp seals (Phoca groenlandica), grey seals (Halichoerus grypus), and hooded seals (Cystophora cristata), ranging in age from newborn to 14 days. In newborn harp seals the mean mass of the pineal gland was 273 mg (+/- 45 SEM, n = 11), containing 49 ng (median) melatonin. In newborn, 4- and 10-day-old grey seals, the pineal mass was similar, weighing on average 337 mg (+/- 74, n = 6) and containing 90 ng melatonin. Two newborn hooded seal pups had pineals weighing 520 and 1289 mg, with 254 and 7600 ng melatonin, respectively. There were no day-night differences in the pineal contents of melatonin or in the number of pineal beta-adrenergic receptors measured in newborn harp seals, and, in newborn, 4- and 10-day-old grey seals, there were no day-night or age differences in pineal melatonin content. Plasma melatonin levels were 10 times higher in newborn seals than in two 10-day-old grey seals and one 14-day-old harp seal pup. In all seal pups, the levels exhibited a 24-hr rhythmicity, with increasing night- and decreasing daytime concentrations. Plasma levels of thyroxine (T4) and triiodothyronine (T3) were generally higher in newborn seals than in 10- and 14-day-old seals or in adult females. There was no apparent 24-hr rhythmicity, but the thyroid hormone levels generally declined throughout each sampling sequence. High pineal and thyroid activities may play a thermoregulatory role in newborn seals, but the results do not indicate a stimulatory action of melatonin in the peripheral conversion of T4 to T3. It is speculated that the large and active pineal gland, particularly in newborn seals, may be related to aspects of their diving habit.
Gen Comp Endocrinol 1995 Jun
PMID:Pineal and thyroid functions in newborn seals. 762 91

Changes in the pituitary cells involved in amphibian metamorphosis were studied in Bufo arenarum tadpoles with inhibited thyroid function. After hatching, larvae were treated for 5 months with potassium perchlorate (KClO4), a goitrogenic substance known to prevent absorption of iodine from water or food, resulting in impaired thyroid hormone synthesis. Treated larvae continued to grow but halted their development in premetamorphosis, showing hyperplastic thyroid glands with disorganized follicles lacking colloid. Thyrotrop (TSH), lactotrop (PRL), somatotrop (GH), and corticotrop (ACTH) cells were stained immunocytochemically and the changes observed were evaluated morphometrically using an automatic image analyzer. Pars distalis volume increased in treated larvae. Morphometric results showed that, in treated tadpoles, TSH and PRL cell populations and cell volumes increased compared to normal larvae at the same stage. Changes in the GH and ACTH cell morphometry were slight. These results indicate that in Bufo tadpoles, after chronic thyroid hormone withdrawal, TSH, PRL, GH, and ACTH cells are able to develop and that thyroid hormones exert a strong feedback control on the synthesis and storage of TSH and PRL.
Gen Comp Endocrinol 1995 May
PMID:Immunocytochemical and morphometric study of TSH, PRL, GH, and ACTH cells in Bufo arenarum larvae with inhibited thyroid function. 763 70

Metamorphosis was induced in neotenic axolotls by immersion of the animals in a solution of thyroid hormone. Hematology of the axolotls was examined before, during, and after metamorphosis. There was a transient decrease in numbers of certain white blood cells during metamorphic climax and a permanent shift in the pattern of circulating cells. The eosinophilic granulocyte was the dominating leukocyte type in neotenes and in metamorphosing animals up to midclimax. Lymphocytes and neutrophilic granulocytes (polymorphs) significantly decreased during midclimax. In postmetamorphic axolotls, lymphocytes and polymorphs predominated. The observed decrease of some leukocytes in metamorphosing animals accords with a transient immunosuppression at metamorphic climax. Metamorphosed axolotls showed a humoral immune response (increase in circulating plasma cells) after repeated antigen challenge, whereas neotenic axolotls did not. Alterations in both cellular and humoral immunity are suggested to occur in both young and adult axolotls following experimental induction of metamorphosis.
Gen Comp Endocrinol 1995 Mar
PMID:Effect of induced metamorphosis on the immune system of the axolotl, Ambystoma mexicanum. 778 46


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