THYROID HORMONE-BINDING INTERACTIONS IN CYTOSOL OF RAT ANTERIOR PITUITARY

1977 ◽  
Vol 85 (2) ◽  
pp. 256-266 ◽  
Author(s):  
Valerie Anne Galton
Keyword(s):  
Thyroid Hormone ◽  
Binding Sites ◽  
Anterior Pituitary ◽  
Binding Capacity ◽  
Relative Effectiveness ◽  
Binding Activity ◽  
Rat Tissues ◽  
Hormone Binding ◽  
Cytosol Fraction ◽  
Binding Interactions

ABSTRACT Thyroxine (T4) and triiodothyronine (T3)-binding interactions in preparations of rat anterior pituitary gland have been studied. T4 is bound primarily to extranuclear binding sites located in the cytosol fraction of the cell. These sites have a medium affinity for T4: Ka = 2.5 × 108 1/mol and a maximum binding capacity (MBC) of 1.15 pmol/mg tissue (wet weight). Binding of T3 to these sites is minimal. The extent of binding of T4 is influenced by the pH of the system and the temperature of incubation. The relative effectiveness of T4 analogues in displacing bound T4 is tetrac > T4 > triac > D-T4 > T3. Similar T4-binding sites are present in other rat tissues, but in all except serum, binding activity is lower than in the pituitary. T4-binding by serum contaminating the pituitary preparations contributed only partially to the total activity observed. Concomitant assessment of T4-binding activity and T4 metabolism in pituitary homogenates prepared at different pH values indicated an inverse relationship between the two processes. The possible role of thyroid hormone binding in cytosol in influencing the intracellular distribution of thyroid hormones is discussed.

scholarly journals A spin label study of the thyroid hormone-binding sites in human plasma thyroxine transport proteins.

1981 ◽  
Vol 256 (2) ◽  
pp. 831-836
Author(s):  
S.Y. Cheng ◽  
G. Rakhit ◽  
F. Erard ◽  
J. Robbins ◽  
C.F. Chignell
Keyword(s):  
Thyroid Hormone ◽  
Human Plasma ◽  
Spin Label ◽  
Binding Sites ◽  
Transport Proteins ◽  
Hormone Binding ◽  
Label Study

scholarly journals Modulation of SHBG binding to testosterone and estradiol by sex and morbid obesity

2017 ◽  
Vol 176 (4) ◽  
pp. 393-404 ◽  
Author(s):  
María del Mar Grasa ◽  
José Gulfo ◽  
Núria Camps ◽  
Rosa Alcalá ◽  
Laura Monserrat ◽  
...  
Keyword(s):  
Morbid Obesity ◽  
Binding Sites ◽  
Binding Capacity ◽  
Specific Binding ◽  
Sex Hormone Binding Globulin ◽  
Morbidly Obese ◽  
Hormone Binding ◽  
Anthropometric Measures ◽  
Obesity Status ◽  
And Gender

ObjectiveSex hormone-binding globulin (SHBG) binds and transports testosterone and estradiol in plasma. The possibility that SHBG is a mixture of transporting proteins has been postulated. We analyzed in parallel the effects of obesity status on the levels and binding capacity of circulating SHBG and their relationship with testosterone and estradiol.DesignAnthropometric measures and plasma were obtained from apparently healthy young (i.e. 35 ± 7 years) premenopausal women (n = 32) and men (n = 30), with normal weight and obesity (BMI >30 kg/m2).MethodsSHBG protein (Western blot), as well as the plasma levels of testosterone, estradiol, cortisol and insulin (ELISA) were measured. Specific binding of estradiol and testosterone to plasma SHBG was analyzed using tritium-labeled hormones.ResultsSignificant differences in SHBG were observed within the obesity status and gender, with discordant patterns of change in testosterone and estradiol. In men, testosterone occupied most of the binding sites. Estrogen binding was much lower in all subjects. Lower SHBG of morbidly obese (BMI >40 kg/m2) subjects affected testosterone but not estradiol. The ratio of binding sites to SHBG protein levels was constant for testosterone, but not for estradiol. The influence of gender was maximal in morbid obesity, with men showing the highest binding/SHBG ratios.ConclusionsThe results reported here are compatible with SHBG being a mixture of at least two functionally different hormone-binding globulins, being affected by obesity and gender and showing different structure, affinities for testosterone and estradiol and also different immunoreactivity.

THE EFFECT OF CHORIOCARCINOMA ON SERUM THYROID HORMONE-BINDING CAPACITY

1967 ◽  
Vol 39 (1) ◽  
pp. 21-26 ◽  
Author(s):  
JENNIFER D. GODDEN ◽  
E. S. GARNETT ◽  
I. F. SOMMERVILLE ◽  
K. D. BAGSHAWE
Keyword(s):  
Thyroid Hormone ◽  
Binding Capacity ◽  
Hormone Binding ◽  
Serum Thyroid Hormone ◽  
Uptake Test ◽  
Uptake Method ◽  
Trophoblastic Tumours

SUMMARY Thyroid hormone binding capacity in serum was measured indirectly by a [131I]tri-iodothyronine (T3) resin uptake method in 36 patients with trophoblastic tumours. A low [131I]T3 resin uptake (raised thyroid hormone-binding capacity) was found in approximately one-third of the patients but none showed clinical or other evidence of hypothyroidism. There was no correlation between [131I]T3 resin uptake test and gonadotrophin excretion. The results suggest that the increased thyroid-hormone binding capacity found in some patients with trophoblastic tumours may be related to oestrogen secretion and further study is required to establish this.

TRIIODOTHYRONINE BINDING TO LYMPHOCYTES FROM EUTHYROID SUBJECTS AND A PATIENT WITH PERIPHERAL RESISTANCE TO THYROID HORMONE

1976 ◽  
Vol 83 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Kristian Liewendahl
Keyword(s):  
Thyroid Hormone ◽  
Binding Sites ◽  
Binding Capacity ◽  
Human Lymphocytes ◽  
Peripheral Resistance ◽  
Subsequent Treatment ◽  
Affinity Constant ◽  
Prolonged Incubation ◽  
Resistance To Thyroid Hormone ◽  
The Mean

ABSTRACT Triiodothyronine (T3) binding to Ficoll-Isopaque purified human lymphocytes was studied. During incubation of lymphocytes with [125I]T3 in a calcium-free medium at 37°C, maximal uptake of T3 in nuclei occurred after 2 h and declined after prolonged incubation. Incubation of lymphocytes with T3 concentrations ranging from 1 × 10−11 to 1 × 10−9 mol/l and subsequent treatment with Triton X-100 to strip off [125I]T3 bound with low affinity was used for the estimation of affinity and capacity of nuclear T3 binding sites. The mean equilibrium affinity constant (Ka) estimated with the Scatchard method in 11 euthyroid healthy subjects was 4.5 × 109 1/mol, and the mean maximal binding capacity 25 × 10−15 mol/100 μg DNA. In a female patient with peripheral resistance to thyroid hormone action, the estimated Ka was 3.5 × 109 1/mol and the number of T3 binding sites 37 × 10−15 mol/100 μg DNA. Although not statistically different from the mean value in euthyroid subjects, this Ka value was outside the range of control values observed and was considered presumptive evidence that the nuclear T3 receptors in this patient have abnormally low affinity for its ligand. The nuclear T3 binding capacity in this patient was significantly increased.

Changes in cytosolic 3,5,3′-tri-iodo-l-thyronine (T3) binding activity during administration of l-thyroxine to thyroidectomized rats: cytosolic T3-binding protein and its activator act as intracellular regulators for nuclear T3 binding

1989 ◽  
Vol 123 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Y. Nishii ◽  
K. Hashizume ◽  
K. Ichikawa ◽  
T. Miyamoto ◽  
S. Suzuki ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Nuclear Receptor ◽  
Binding Capacity ◽  
Binding Protein ◽  
Binding Activity ◽  
Affinity Constant ◽  
Maximal Binding

ABSTRACT Changes in the amount of cytosolic 3,5,3′-tri-iodo-l-thyronine (T3)-binding protein (CTBP) and its activator during administration of l-thyroxine (T4) to thyroidectomized rats were investigated. Thyroidectomy decreased the amount of CTBP in the kidney, whereas the activator was not significantly modified by thyroidectomy. The activator was increased by administration of T4 to thyroidectomized rats. The amount of CTBP was also increased by administration of T4. The activator increased the maximal binding capacity (MBC) without changes in the affinity constant for T3 binding in CTBP. A T4-induced increase in MBC in cytosol inhibited nuclear T3 binding in vitro by competition of T3 binding between CTBP and the nuclear receptor. These results suggest that thyroid hormone increases the capacity for cytosolic T3 binding through increasing the amount of CTBP and its activator, and that these increases play a role in regulating the amount of T3 that binds to its nuclear receptor. Journal of Endocrinology (1989) 123, 99–104

Increase in pituitary dopaminergic receptors after monosodium glutamate treatment

1983 ◽  
Vol 245 (3) ◽  
pp. E261-E265
Author(s):  
M. L. Heiman ◽  
N. Ben-Jonathan
Keyword(s):  
Binding Sites ◽  
Anterior Pituitary ◽  
Arcuate Nucleus ◽  
Binding Capacity ◽  
Monosodium Glutamate ◽  
Male Rats ◽  
Single Class ◽  
Binding Characteristics ◽  
Physiological Conditions ◽  
Da Receptors

We investigated whether a decrease in arcuate nucleus dopamine (DA) levels resulting from neonatal treatment with monosodium glutamate (MSG) affects the anterior pituitary DA receptors in adult male rats. MSG treatment resulted in a significant reduction in medial basal hypothalamic (MBH) DA levels, no change in its norepinephrine (NE) and epinephrine (E) concentrations, and a marked increase in circulating prolactin (PRL). Scatchard analyses of DA binding characteristics to anterior pituitary membranes using [3H]spiperone revealed linear plots, suggesting a single class of high-affinity, low-capacity binding sites. The DA binding capacity was significantly higher in MSG-treated rats than in controls with no change in affinity. The data indicate that anterior pituitary DA receptors change in accordance with altered physiological conditions. The increase in the number of DA receptors following destruction of the arcuate nucleus is probably a direct effect of reduced DA levels reaching the anterior pituitary gland.

Expression and binding activity of the glucocorticoid receptor are upregulated in septic muscle

2002 ◽  
Vol 282 (2) ◽  
pp. R509-R518 ◽  
Author(s):  
Xiaoyan Sun ◽  
David R. Fischer ◽  
Timothy A. Pritts ◽  
Curtis J. Wray ◽  
Per-Olof Hasselgren
Keyword(s):  
Skeletal Muscle ◽  
Glucocorticoid Receptor ◽  
Binding Sites ◽  
Cecal Ligation ◽  
Binding Activity ◽  
Scatchard Analysis ◽  
Regulatory Effect ◽  
Hormone Binding ◽  
Experimental Conditions ◽  
Protein Levels

We examined the influence of sepsis, induced by cecal ligation and puncture in rats, on the protein and gene expression and hormone binding activity of the glucocorticoid receptor (GR) in skeletal muscle. Sepsis resulted in increased GR mRNA and protein levels and upregulated hormone binding activity in extensor digitorum longus and soleus muscles. Scatchard analysis suggested that the increased GR hormone binding activity reflected an increased number of hormone binding sites, whereas receptor affinity for glucocorticoids was unchanged. The GR antagonist RU-38486 blocked the sepsis-induced increase in GR expression and hormone binding activity, implicating a positive regulatory effect of glucocorticoids on GR expression and binding activity under the present experimental conditions. The results suggest that glucocorticoid-dependent metabolic changes in skeletal muscle during sepsis may reflect not only high circulating glucocorticoid levels but increased amounts and hormone binding activity of the GR as well.

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