Thyroid Function in Rats and Chickens. Equilibration of Injected Iodide with Existing Thyroidal Iodine in Long-Evans Rats and White Leghorn Chickens1

Rosenberg, Lawson L.; Goldman, Max; Dimick, M. K.

doi:10.1210/endo-74-2-212

Cited by 33 publications

(13 citation statements)

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“…Besides these two compounds, azide, ascorbic acid and reduced glutathione inhibited the enzyme significantly. This inhibition of the iodination reaction by reduced glutathione confirms the earlier observation of Schussler and Ingbar [1961]. PCMB (parachloromercuribenzoate) had very little effect but the stimulatory effect of IAA (iodoacetic acid) was so striking that it led us to study the effect of different concentrations of this compound on the enzyme (Fig.…”

Section: Resultssupporting

confidence: 87%

“…Though there are substantial reports on in vivo work on avian thyroid gland [Kobayashi and Gorbman, 1960;Rosenberg et at., 1964] practically no report is available on the in vitro synthesis of iodotyrosines catalysed by any enzyme preparation from avian thyroid gland. As in the observations of some previous workers [Cunningham and Kirkwood, 1961;Alexander, 1959;Hati and Datta, 1967] in mammalian iodinating enzymes, the pigeon enzyme is also dependent on copper for its activity.…”

Section: Discussionmentioning

confidence: 99%

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STUDIES ON THE IN VITRO FORMATION OF MONOIODOTYROSINE BY SOLUBLE SUPERNATANT OF PIGEON THYROID GLAND

Bhattacharya¹,

Datta²

1970

Exp Physiol

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A soluble supernatant preparation of pigeon thyroid gland can catalyse the iodination of tyrosine to monoiodotyrosine in vitro. The enzyme needs a hydrogen peroxide generative system such as glucose and glucose oxidase or Cu2+ for its activity. The optimum concentration of Cu2+ was found to be 1·33 x 10−3 M. Direct and slow addition of hydrogen peroxide cannot be substituted for Cu2+. Antithyroid agents like thiourea and thiouracil are found to be more potent inhibitors of avian enzyme than of mammalian enzyme. Ascorbic acid inhibits the enzyme but stimulates remarkably when a dialysed enzyme is used instead of an undialysed one.

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Section: Resultssupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

STUDIES ON THE IN VITRO FORMATION OF MONOIODOTYROSINE BY SOLUBLE SUPERNATANT OF PIGEON THYROID GLAND

Bhattacharya¹,

Datta²

1970

Exp Physiol

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“…It is not known if thyrotropin-releasing hormone (TRH) secretion can also be elicited by photostimulation. Although the pituitary thyrotropic function of birds depends less on hypothalamic control than does that of mammals (Rosenberg et al, 1964), interrupting the hypothalamohypophyseal connection does reduce thyroid weight, metabolism, and secretion (Takahara et al, 1967;Ringer, 1976).…”

Section: Resultsmentioning

confidence: 99%

Effects of Light Environment and Pinealectomy on Growth and Thyroid Function in the Broiler Cockerel

1980

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Four replicate experiments were conducted to determine the effects of pinealectomy and environmental lighting on growth and thyroid function in broiler cockerels. Birds were housed in battery brooders under a 14L:10D white light regime for 2 weeks and then allotted to lightcontrolled chambers. The light environments were 14L:10D white, 14L:10D green (narrow band, 545 nm peak), and constant dark. Surgery was performed when the chicks were 3 to 5 days old. At the end of the 32-day experimental period, weight gain and thyroid weights were measured and plasma triiodothyronine (T 3 ) and thyroxine (T 4 ) levels were determined by radioimmunoassay.Pinealectomy significantly (P<.05) depressed growth but did not affect thyroid weight or circulating plasma levels of T 3 or T 4 .Birds grown under white light were significantly (P<,05) lighter in weight than those grown under green light or darkness. Plasma T 4 levels were significantly (P<.05) elevated in chicks grown under green light while T 3 levels were signficantly (P<.05) higher in dark-treated birds when compared to either light treatment.

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“…after the injection of 131I was selected since it had been suggested that the relative pro¬ portion of the labelled compounds reaches a steady state within this interval (Mayberry & Astwood, 1960;Pitt-Rivers, 1962). However, recent work has shown that the injected 131I requires 2-4 days to achieve complete equilibrium with the existing thyroidal 127I, depending on the level of dietary iodine intake (Rosenberg, Goldman, La Roche & Dimick, 1964). Therefore, the proportions of labelled iodoaminoacids should not be considered as equivalent to the absolute amounts of these compounds present.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Prolonged Feeding of Goitrogens on Thyroid Function in Rats

Broadhead¹,

Pearson²,

Wilson³

1965

Journal of Endocrinology

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Graded doses of propylthiouracil, carbimazole, sulphadiazine, potassium perchlorate and potassium thiocyanate were fed to groups of rats under standardized conditions for 2 months. The rats were given 131I 24 hr. before they were killed, and the thyroid weight, the proportions of labelled iodoaminoacids, and the thyroidal iodine content were determined. All the goitrogens produced increase in thyroid size, reduction of thyroidal iodine content, and an elevation of the monoiodotyrosine : di-iodotyrosine (MIT : DIT) ratio. The tri-iodothyronine : thyroxine (T3 : T4) ratio was usually increased. Irrespective of the antithyroid compound used, there was a close correlation between the decrease in thyroidal iodine content and the rise in the MIT:DIT ratio.In further experiments, either thyroid stimulating hormone (TSH) or thyroxine were injected s.c. twice daily for 5 days. TSH decreased the MIT:DIT ratio and increased the amount of labelled T3. Thyroxine increased the MIT : DIT ratio and decreased the amount of T4.It is suggested that when goitrogens were administered for a prolonged period, the pattern of 131I-labelling of iodoaminoacids was dependent on a balance between inhibition of synthesis caused by the goitrogen and stimulation due to TSH. There was increased production of the physiologically more economical T3 in an attempt to compensate for decreased thyroxine formation.

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Thyroid Function in Rats and Chickens. Equilibration of Injected Iodide with Existing Thyroidal Iodine in Long-Evans Rats and White Leghorn Chickens1

Cited by 33 publications

References 0 publications

STUDIES ON THE IN VITRO FORMATION OF MONOIODOTYROSINE BY SOLUBLE SUPERNATANT OF PIGEON THYROID GLAND

STUDIES ON THE IN VITRO FORMATION OF MONOIODOTYROSINE BY SOLUBLE SUPERNATANT OF PIGEON THYROID GLAND

Effects of Light Environment and Pinealectomy on Growth and Thyroid Function in the Broiler Cockerel

The Effect of Prolonged Feeding of Goitrogens on Thyroid Function in Rats

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