Showing papers on "Glucocorticoid published in 1971"

Glucocorticoid Receptors in Lymphoma Cells in Culture: Relationship to Glucocorticoid Killing Activity

Abstract: Mouse lymphoma cells in culture which are killed by adrenal steroids contain specific cortisol receptors that may be involved in the initial events of hormone action The similarity of these receptors to those in hepatoma tissue culture cells, where adrenal steroids induce tyrosine aminotransferase, suggests that certain aspects of steroid action are similar in the two systems In three steroid-resistant lymphoma cell populations specific binding was less than in the parent lines, suggesting that conversion to steroid resistance may be associated with changes in specific steroid binding

Autoradiographic techniques and the localization of estrogen, androgen, and glucocorticoid in the pituitary and brain

Abstract: SYNOPSIS. Autoradiographic techniques are reviewed which have been recommended. for the localization of diffusible substances, such as steroid hormones. Advancement in techniques, including low temperature tissue sectioning, section freeze-drying, and dry-mounting of sections, led to the development of the dry-mount autoradiographic technique. This progress in technique has enabled the cellular and subcellular topotgraphic localization of steroid hormones in peripheral and central target tissues, including the identification of hormone target cells in the pituitary and mapping of hormone neurons in the brain. In the pituitary, tritiated estrogen, androgen, and glucocorticoid are concentrated and retained in nuclei of certain anterior lobe cells. In the brain, estrogens, androgens, and glucocorticoids are attracted by and concentrated in nuclei of certain neurons located mainly within the phylogenetically old periventricular brain. In view of the widespread distribution of sex steroids in different brain areas, the generally held concept of a topographically confined single or dual “sex center” is challenged. While estrogen and androgen neurons in the hypothalamus, in the preoptic-septal-parolfactory region, and in the amygdala overlap, or are even identical in part, glucocorticoid neurons are more heavily concentrated in the gyrus dentatus, hyppocampus, indusium griseum, dorsal nuclei septi lateralis and medialis, as well as in the piriform cortex and portions of the amygdala. It is conceptualized that the steroid hormone neurons are hypophysiotropic neurons, being involved in the neurosecretion of releasing factors, and that they represent sought for hormone “feedback” areas in the brain. This challenges the generally held view of the “hypophysiotrophic area” in the hypothalamus as the anatomical site where releasing factors are produced.

Stereospecific glucocorticoid binding to subcellular fractions of the sensitive and resistant lymphosarcoma P1798.

Abstract: WE have shown that in vitroexposure of cells of these PI798 tumours to physiological doses of glucocorticoids produces significant inhibition of DNA, RNA and protein metabolism1–3 and glucose uptake2, 4 only in the glucocorticoid-sensi-tive tumour. These glucocorticoid-induced inhibitions can be correlated with the inhibition of growth and subsequent regression and dissolution of the sensitive tumour. In this study we have carried out competition experiments using the two 11-hydroxy isomers of Cortisol which have been shown to have the requisite stereospecific restraints necessary to show specific glucocorticoid binding5. It would be reasonable to suppose that both the 11α and 11β-isomers of Cortisol would compete almost equally for nonspecific binding sites of triamcinolone acetonide. But since only 11β-cortisol has glucocorticoid activity, only this isomer could compete with triamcinolone acetonide for specific binding. Thus, the difference in displacement caused by these two 11-hydroxy isomers is an indication of the specific binding of 3H-triamcinolone acetonide to different fractions of the PI 798 tumour.

Relationship of protein synthesis and cyclic AMP to lipolytic action of growth hormone and glucocorticoids

Abstract: The addition of growth hormone and glucocorticoid enhances lipolysis is isolated white fat cells from rats after a lag period of 1 to 2 hours. We have postulated that this lag period is required for synthesis of protein via a mechanism requiring DNA-dependent RNA synthesis. The present studies with cycloheximide, an inhibitor of protein synthesis, support the hypothesis that protein synthesis is involved in the action of these hormones. When cycloheximide was added with growth hormone and glucocorticoid, it blocked their lipolytic action, its effects were reversible, and the cycloheximide sensitive process occurred during the early time period after addition of the hormones. The incorporation of leucine into total fat cell protein was inhibited by growth hormone and glucocorticoids during the first 2 hours and stimulated during the second 2 hours of incubation. The protein made under the influence of growth hormone increases the maximal accumulation of cyclic AMP seen in response to lipolytic agents. Dexamethasone did not enhance the accumulation of cyclic AMP. In cells incubated with insulin for 3 hours prior to addition of epinephrine and theophylline no effect of insulin on cyclic AMP accumulation was seen during the next 5 minutes except in the presence of growth hormone. However, in cells incubated with insulin and lipolytic agents for 15 minutes there was a marked inhibition by insulin of total cyclic AMP accumulation under all conditions.

Glucocorticoid Receptors in Rat Thymus Cells

Abstract: Summary Studies of binding of glucocorticoids to rat thymus cells in vitro demonstrate two forms of binding: (a) Specific binding, which is well correlated with glucocorticoid activity, saturates at high physiological concentrations, and is characterized by slow association and dissociation. Specific binding appears to represent association with glucocorticoid receptors. With cortisol no metabolic transformation precedes this association. (b) Non-specific binding, which correlates with nonpolarity and interfacial activity, does not saturate, and is characterized by rapid association and dissociation. With all steroids tested this is the major fraction. It is distributed throughout the cell including the nucleus, accounting for the well-known nonspecific effects of steroids in vitro. ATP or some related substance may be necessary for specific binding in whole cells. A competitor for specific glucocorticoid binding, cortexolone, blocks the hormonal activity of cortisol. If cells are disrupted by hypotonic shock in 1.5 mM MgCl2 after incubation with cortisol at 20 °C or 37 °C most of the specifically bound hormone sediments with nuclei. But after incubation at 3 °C the hormone is mainly in the supernatant. For convenience the supernatant fraction is referred to as “cytoplasmic”. Cortisol in both the nuclear and “cytoplasmic” fractions is bound to macromolecules. These “receptors” are in part proteins. The binding properties – specificity, saturation, dissociation rates – of the isolated receptors, both of which can be extracted from cells that have not been preexposed to cortisol, are similar to those characteristic of specific binding to cells at 37 °C, showing that specific binding to cells at 37 °C displays the intrinsic properties of the receptor complexes. Cortisol bound to “cytoplasmic” receptors is rapidly transferred to the nucleus even in the presence of excess unlabelled cortisol, indicating that formation of the cytoplasmic complex is an obligatory step. The receptors do not appear to be ‘carriers’ since the cells are freely permeable to glucocorticoids. It is suggested that the hormone directs the cytoplasmic receptor to the nuclear site by increasing its affinity for the nuclear site and/or by releasing it from some initial site. To initiate metabolic activity the receptor probably has to have attached an active hormone molecule, since with cortexolone a nuclear steroid-receptor complex appears to be formed but activity is not initiated.

The Prematurely Evoked Synthesis of Liver Tryptophan Oxygenase

Abstract: Livers of normal rats are devoid of catalytically or immunochemically reactive tryptophan oxygenase (EC 1.13.1.12) up to the 10th postnatal day; the enzyme reaches adult concentrations on about the twentieth day. Premature tryptophan oxygenase synthesis can be evoked in 4-day-old rats: if an injection of glucocorticoid is followed, a day later, by an injection of tryptophan, adult levels of tryptophan oxygenase activity and antigen content can be attained within 5 hr. The prematurely evoked tryptophan oxygenase is degraded in about 2 days, but the preparatory action of the glucocorticoid is longlasting. Even 4 days later, an injection of tryptophan can evoke significant enzyme formation. Actinomycin D, injected together with or 12 hr before the tryptophan, is not inhibitory, but if injected with the glucocorticoid it prevents enzyme formation upon later injection of tryptophan. The observations suggest that appearance of the new enzyme in developing tissue results from the sequential action of more than one stimulus and that the potentiality for its transcription may develop long before its actual synthesis.

Glucocorticoid Hormone Receptors

Abstract: Summary The available data lead us to conclude that steroid binding to the specific glucocorticoid receptor in HTC cells is an important event in the hormone-mediated induction of both tyrosine aminotransferase (TAT) and cell adhesiveness because: 1. The kinetics of dexamethasone binding to and dissociation from the specific receptor are rapid enough to account for the rapid kinetics of induction and deinduction of TAT. 2. Plots of specific steroid binding, induction of TAT, and induction of cell adhesiveness as a function of dexamethasone concentration are very similar. 3. The binding characteristics of a number of steroids (including inducers, anti-inducers and inactive steroids) parallels their biological activity. After incubation of HTC cells with 3 H–dexamethasone at 37° C, specific macromolecular binding of 3 H can be found in both the nuclear and cytoplasmic fractions. However, in cell-free incubations, most of the binding activity is in the cytoplasmic fraction. Therefore, nuclear localization of specifically bound radioactivity may occur only after the initial binding reaction in the cytoplasm. The receptor are very probably proteins, which sediment in sucrose gradients near 4S at 0.5M KCl and 8S at lower ionic strength. Binding is inhibited by mercurials and by 1M KCl. The dissociation constant for the reaction dexamethasone + receptor ⇌ dexamethasone-receptor complex determined at 0-5 C by equilibrium studies is 3.0 × 10 −9 M and by kinetic analysis is 7.4 × 10 −10 M. Specific glucocorticoid binding which is similar to that in HTC cells, also occurs in rat liver and in mouse lymphoid cell lines, suggesting that the initial binding reaction is similar even in tissues whose responses to glucocorticoids are quite different. Also steroid resistant lymphoma cells showed decreased specific binding compared with steroid-sensitive parent lines. How the specific receptors are actually involved in enzyme induction is unknown although they do not appear themselves to be the labile post-transcriptional repressor of TAT synthesis predicted from other data.

In vitro induction of tyrosine aminotransferase in liver slices by hydrocortisone.

Abstract: A liver slice system has been developed which actively incorporates labeled precursors into RNA and protein for as long as 10 h of incubation. The addition of glucocorticoid induces tyrosine aminotransferase (TA) in liver slices of hypophysectomized rats but not in liver homogenates of hypophysectomized rats or in slices derived from normal rats. TA activity is increased two- to sixfold during 6 h of incubation, the maximal response being observed with 10−6 M steroid. Addition of cydoheximide, at a concentration which depresses protein synthesis 95%, blocks the accumulation of TA. The half-life of induced TA is approximately 2–3 h and is similar to that of the basal, noninduced system. These data indicate that glucocorticoid acts only to increase the rate of TA synthesis without affecting its rate of degradation.

Glucose tolerance testing after intravenous betamethasone phosphate, with concomitant uric acid and cholesterol analyses. A reassessment of both glucocorticoid and afternoon testing in «Early Chemical Diabetes»

Abstract: The intense, sustained and predictable glucocorticoid action of i.v. betamethasone disodium phosphate (BSP) has been used as an effective method of stressing the insulinogenic reserve before glucose tolerance testing (GTT). The 13 selected patients in this study received 4.5 mg of BSP 16 to 18 hrs before ingesting a 100 g glucose load. «Early chemical diabetes» was suspected in 8 patients on the basis of the following: 1) clinical features such as hypercholesterolemia, transient glucosuria, diabetic-like peripheral neuropathies, gout, and large babies; 2) a family history of diabetes, especially when bilateral; and 3) nondiabetic or equivocal responsesboth by conventional morning glucose tolerance testing (MGTT) and afternoon glucose tolerance testing (AGTT).Every patient showed an unequivocal diabetic response after BSP priming. Five patients evidencing decreased glucose tolerance by AGTT, but not by MGTT, also were studied. Their diabetic diathesis was readily confirmed by BSP-GTT, even after improvement of glucose tolerance had been evidenced by repeat AGTT following treatment with diet and oral hypoglycemic drugs. The diagnostic and prognostic usefulness of corticosteroid-GTT remains limited, since it imposes apharmacologic stress upon the insulinogenic reserve. This contrasts with thephysiologic method of AGTT, which has demonstrated decreased tolerance in most diabetic suspects whose responses to MGTT proved nondiabetic or equivocal. Prognostically, depletion of the insulinogenic reserve is probably more advanced in the patient with «early chemical diabetes» whose diagnostic hyperglycemia is demonstrable by AGTT than when it can be evoked only after glucocorticoid priming. The paradoxic postglucose rise in the uric acid concentration, cholesterol concentration, or both, during AGTT and BSP-GTT in certain patients has been demonstrated. The implications of these phenomena relative to the pathogenesis and treatment of gout, hypercholesterolemia, and «secondary sulfonylurea failure» are discussed.