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PubMed1975

Time course of the effect of adrenalectomy on transcortin binding characteristics: appraisal of different methods of calculation.

The time course effect of adrenalectomy on the transcortin-corticosterone association constant (KT), its concentration of binding sites (ST) and the corresponding binding constant (SAKA) of albumin has been investigated by equilibrium dialysis at 37 C on plasma samples collected 0, 3, 6, 12, 24, 48, 96 and 144 h after adrenalectomy in male adult rats. The data have been analyzed by 3 different methods: a graphical Scatchard analysis using bound over unbound versus bound as representation axes and 2 least squares minimization methods in which axes were, respectively, bound over total versus mass of corticosterone added and total versus unbound. Confidence regions can be computed in the last two methods allowing the statistical comparison of the different dialysis experiments. Results obtained by the three methods are quite similar and led to the conclusions that following adrenalectomy KT was constant while ST varied. The observed pattern was a decrease until the first 24 h followed by a rise reaching almost twice the control value at 144 h. It would also appear that SAKA decreases slightly within 24 h following adrenalectomy.

Adrenalectomy↗
PubMed1983

Effects of various replacement oestrogens on hepatic transcortin synthesis in climacteric women.

The influence of peri-menopausal oestrogen replacement therapy upon protein synthesis in the liver was investigated. Changes in the cortisol-binding capacity of transcortin (TC-BC) were utilized as an indicator of hepatic oestrogen sensitivity. Forty-two climacteric women were studied before and after treatment with various drugs at different doses (patients receiving identical compounds served as their own controls for the evaluation of dosage effects; duration of medication: 14 days at each dose). Oral administration of oestriol (1 and 2 mg daily; n = 6), oestriol (1 and 2 mg daily) + oestradiol-17 beta (2 and 4 mg daily; n = 8), oestradiol valerate (1, 2, 4 and 6 mg daily; n = 6), conjugated equine oestrogens (0.3 and 0.6 mg daily; n = 6), sodium oestrone sulphate (0.8 and 1.6 mg daily) + sodium equilin sulphate (0.2 and 0.4 mg daily; n = 6) and quinoestrol (25 micrograms daily; n = 6) failed to alter TC-BC. However, ingestion of higher doses of conjugated equine oestrogens (0.9 and 1.25 mg daily; n = 5) and quinoestrol (50 micrograms daily; n = 6) caused a significant rise (P less than 0.01). Ethinyloestradiol was given orally as a reference substance and elicited an elevation of expected magnitude. Vaginal administration of dienoestrol cream (1 mg daily; n = 4) did not change TC-BC. These data indicate that the hepatotrophic effects of replacement oestrogens vary depending on the preparation and dosage selected for treatment.

Climacteric↗
PubMed1978

Relationship between the pituitary gland and gonadal steroids: involvement of a hypophysial factor in reduced alpha 2u-globulin and increased transcortin concentrations in rat serum.

Evidence is presented that the level of alpha 2u-globulin in the serum of male rats depends, at least in part, on neonatal androgens. After castration of adult animals the concentration of this protein falls but remains measurable, whereas in intact or ovariectomized female rats alpha 2u-globulin cannot be detected. Moreover, alpha 2u-globulin is found in adult male and female rats gonadectomized at birth and treated with a single injection of testosterone propionate immediately thereafter. The mechanism by which neonatal androgens increase the concentration of alpha 2u-globulin has been investigated. Transplantation of a supplementary pituitary gland under the renal capsule of male rats resulted in reduced levels of alpha 2u-globulin and increased levels of transcortin. The changes discussed here were observed only in those animals in which the transplant was functional and they were amplified or reversed by modulators of prolactin secretion such as oestrogens or bromocriptine respectively. The hypothesis is advanced that neonatal androgens stimulate the production of a hypothalamic inhibitory factor that controls the secretion of prolactin, or another hypophysial hormone subjected to similar neuroendocrine control. Measurements in gonadectomized animals and in rats receiving both oestradiol benzoate and bromocriptine indicate that, besides these pituitary-mediated effects, both oestrogens and androgens exert direct effects on the level of alpha 2u-globulin.

Alpha-Globulins↗
PubMedDate not supplied

[Changes in binding of corticosteroids by transcortin in blood and in oxidative processes in rabbit liver mitochondria under the effect of decimeter waves].

Irradiation of rabbits with decimetre waves (regions of adrenal glands, liver and lower part of thigh) was accompanied by an increased content of free, biologically active corticosteroids in blood plasma due to liberation of the substances from a complex with transcortine. This phenomenon correlated with activation of the electron transport in respiratory chain of liver tissue mitochondria. The irradiation of the liver region caused distinct alteration in mitochondrial functions apparently due to intensified effect of the decimetre waves directly on the liver tissue.

Adrenal Cortex Hormones↗
PubMed1988

[Changes in plasma binding protein of sex steroids and transcortin during the treatment of menopause with oral estrogens].

Sex steroid binding protein (SBP) and transcortin (CBG) plasma concentrations were measured in 15 postmenopausal women before and during oral administration of estradiol 2 mg plus estriol 1 mg given alone for one month and in sequential combination with noresthisterone 1 mg for the following months. The results were compared with those obtained in a group of 13 premenopausal women who were studied during the early follicular phase or during administration of estroprogestagens. The oral administration of estrogens slightly increased CBG levels (56.1 +/- 11.4 vs 46.0 +/- 5.2 mg/l, P less than 0.05) which in 4 patient were higher than in premenopausal women. The mean SBP level was lower in postmenopausal women than in premenopausal women (1.02 +/- 0.40 vs 1.35 +/- 0.38 micrograms/dl, P less than 0.02), and SBP correlated negatively and significantly with the body mass index (r = 0.794, P less than 0.02). On average, SBP increased twofold during the estrogen treatment. In 6 patients the concentrations of estrogen-stimulated SBP were higher than the upper limit for premenopausal women. Lowered SBP levels were normalized during estrogen therapy. During estrogen substitution in the postmenopausal women, the mean E2 to SBP ratio (an index of free estradiol) was within the normal limits for premenopausal women. These results demonstrate that SBP is highly sensitive to oral estrogens. The increase in SBP is associated with a free E2 index which is within the physiological range of premenopausal women. The risk(s) or benefit(s) associated with the increase in SBP during estrogen therapy in postmenopausal women deserve to be evaluated by further investigations.

Administration, Oral↗
PubMed1985

Serum inflammatory responses of transcortin binding activities and of total and free corticosterone and progesterone levels in developing rats: a kinetic approach.

The kinetics of the inflammatory responses of 5 serum parameters involved in specific protein-hormone interactions were studied, namely: transcortin (CBG) binding activities; total corticosterone (B), main ligand of CBG; unbound corticosterone (free B); total progesterone (P4), main competitor of B for binding on CBG; and the free P4. The studies were performed in developing animals, i.e. on rats given a single turpentine injection at 1, 10, 21 or 90 days of post-natal age. The responses showed similar trends at all ages, but age-dependent differences in kinetics and reactivities. Common characteristics were 3-5-fold increases of the hormone parameters as soon as 4-8 h after the injection, and 2-3-fold decreases in CBG activities. A remarkable age-dependent difference was the contrast of early CBG decrease in adults (4 h after turpentine) to the delayed occurrence of this reaction in immatures (8-24 h after turpentine). On the other hand, the increase of free B lasted for 72 h in neonates, but only 40 h in rats treated at 21 or 90 days. Age-dependent characteristics were seen also in reactivities: the peak increases in the hormone levels were highest in the young, while the peak decreases of CBG were most marked in the mature animals. The results suggest that the regulatory mechanisms governing the mutual effects of hormonal activities and CBG synthesis might depend on the stage of development.

Aging↗
PubMed1978

Evaluation of a competitive binding assay for cortisol using horse transcortin.

A non-chromatographic competitive binding assay (CBA) using horse transcortin has been employed in the routine measurement of cortisol in plasma, urine and amniotic fluids. Comparing the values with those of a radioimmunoassay (RIA) or a fluorimetric method (FM) an excellent correlation between the three methods both in plasma and urine has been calculated in normal subjects and in patients with various endocrine disorders. In amniotic fluids, however, there were discrepancies between CBA and RIA. Whereas CBA showed no differences, RIA gave significantly higher values in amniotic fluids of female than of male fetuses. Elevated free plasma cortisol levels observed in patients with prostatic cancer after diethyl stilboestrol diphosphate therapy did not correlate with unconjugated urinary cortisol concentration as measured with CBA and FM. In newborns, a relatively high plasma level found 12 hours after birth was followed by a nadir on the 2nd and 3rd day of life and by an increase until levels of adults on the 5th day of life were reached.

Amniotic Fluid↗
PubMed1984

[Decrease in transcortin binding activity in depression].

In a preliminary study, Cortico-Binding Globuline (CBG) has been determined in 10 depressed major inpatients (DSM3) and compared with healthy volunteers. A clear cut fall of binding activity of transcortin is reported in depressed patients associated with an increase of total and free plasmatic cortisol.

Adult↗
PubMed1980

[Effect of the equilibrium constant of steroid-transcortin binding on the metabolic clearance rate of cortisol and corticosterone in the rabbit].

In the Rabbit the metabolic clearance rate (MCR) was shown to be eightfold greater for corticosterone than for cortisol. This marked difference in the clearance kinetics of both glucocorticosteroids appears to result from a difference in the affinity of transcortin (CBG) towards both hormones, since the maximal association constant of CBG was twice as high for cortisol as for corticosterone.

Aldosterone↗
PubMed1982

Immunoglobulin levels in breast cyst fluid: apparent connection with intracystic transcortin (CBG) binding activity.

Immunoglobulin levels of the major classes of IgG, IgA and IgM have been measured by radial immunodiffusion in 74 samples of breast cyst fluid (BCF) aspirated by women with "Gross Cystic Disease". Appreciable levels of Ig were found in all samples. No significant correlation was observed between intra-cystic Ig levels and the corresponding levels measured on coincidental blood specimens. A significant linear correlation was found between intra-cystic Ig levels and the apparent specific binding activity for cortisol attributable to a transcortin like component (n = 30; p less than 0.05 for IgA, p less than 0.0025 for IgG; p less than 0.05 for IgM).

Adult↗
PubMed1994

[Synthesis and characteristics of anti-CBG antibodies (anti-transcortin)].

We used corticosteroid binding globulin purified by chromatography on the Sepharose column for immunisation of the rabbits. We analysed serum by rocket immunoelectrophoresis and cross immunoelectrophoresis. The titre of the serum was estimated by reaction with 125 I-labelled transcortin (corticosteroid binding globulin). The results of our studies indicate that own serum is valuable and can be use for radioimmunoassay of the CBG in the serum.

Animals↗
PubMedDate not supplied

[Interaction of transcortin with human syncytiotrophoblast].

Interactions of transcortin (corticosteroid-binding globulin, CBG) variants, nCBG and rCBG, present in the blood of pregnant women, and microvesicular fraction of the brush border membrane of human placental syncytiotrophoblast at 23 +/- 2 degrees C were studied. Interaction of nCBG in complex with a steroid with each of the two types for specific binding was found associated with transmembranous transfer of glycoprotein. Interaction of rCBG with binding sites of both types did not involve subsequent glycoprotein transfer through the membrane. Possibility of penetration of only one CBG variant through syncytiotrophoblast membrane suggests the presence of different mechanisms of these glycoproteins' participation in the hormonal effects of steroids associated with them.

Binding Sites↗
PubMed1994

[Isolation and purification of transcortin (cortisol binding globulin--CBG) using two-step chromatography].

The isolation of cortisol and progesterone binding globulin (CBG) from pregnant women serum was performed using affinity and hydrophobic chromatography. The purity and specificity of isolated transcortin was tested by agarose gel electrophoresis using racket and cross immunoelectrophoresis and specific CBG antibodies. High purity and immunoreactivity of the isolated globulin destitute of other proteins contamination, were obtained.

Chromatography↗
PubMed1993

[The effect of steroids on binding of transcortin with human syncytiotrophoblasts].

The effects of steroids on specific binding of transcortin (corticosteroid-binding globulin, CBG) variants (nCBG and vCBG) from pregnant women sera to the microvesicular membrane fraction derived from placental syncytiotrophoblast brush border have been studied. It was shown that native CBG variants stripped of steroids lose their ability to interact with specific membrane sites. Specific binding of CBG variants was found to increase in parallel with an increasing per cent content of glycoproteins associated with cortisol, reaching a maximum at cortisol concentrations of 5.10(-8)-5.10(-7) M which is saturating for the complex formation. Specific binding sites in the syncytiotrophoblast membrane do not differentiate between the nCBG complexed to cortisol, corticosterone, progesterone or testosterone but show a selectivity towards the vCBG-cortisol complex.

Binding Sites↗