Heterogeneity of pituitary glucocorticoid binding evidence for a transcortin-like compound

Koch, Bernard; Lutz, B; Briaud, B.; Mialhe, C

doi:10.1016/0304-4165(76)90393-7

Cited by 68 publications

(12 citation statements)

References 20 publications

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“…Nevertheless, our data showing that the t~ for the free fraction of corticosterone is always greater than for the bound fraction suggest that bound corticosterone may be preferentially metabolized. Tissue uptake of CBG-bound corticosterone is consistent with the presence of intracellular CBG or CBG-like molecules in various glucocorticoid target organs (35,36). Immunocytochemical localization of intracellular CBG has been shown in rat (37) and guinea pig (38) tissues, but there has been some controversy as to the adequacy of experimental controls.…”

Section: Discussionmentioning

confidence: 66%

Kinetics of Circulating Corticosterone in Infant Rats

1988

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ABSTRACT. Corticosterone plays an important role in the regulation of postnatal development in the rat. Basal concentrations of plasma corticosterone increase markedly during the 3rd wk of life. To date, however, the physiologic bases of this increase have remained unclear. To understand the determinants of circulating concentrations of corticosterone during this period, the plasma half-life of disappearance at steady state (tlh), the apparent volume of distribution, and metabolic clearance rate were determined after injection of a tracer dose of 3H-corticosterone in rats at 12, 16, and 22 days of age. The tlh for total plasma corticosterone decreased with increasing age. The volume of distribution decreased even more steeply and, consequently, the MCR displayed a highly significant decline between 12 and 22 days of age. As plasma concentrations of corticosteroid-binding globulin are known to increase markedly during this period, the t~ of protein-bound corticosterone was measured and that of free corticosterone was computed. At all ages the tth of bound corticosterone was less than that of free corticosterone. Protein binding of the injected 3H-corticosterone increased significantly with development. Thus, increased binding of corticosterone is associated with decreased t~. The increasing association of corticosterone with corticosteroid-binding globulin during this developmental period is the most likely explanation for the steep decline of volume of distribution and thus of the metabolic clearance rate for corticosterone. The latter provides, for the first time, an understanding of the basis of the developmental increase in plasma concentrations of corticosterone. (Pediatr Res 24: 595-599,1988)

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Section: Discussionmentioning

confidence: 66%

Kinetics of Circulating Corticosterone in Infant Rats

1988

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“…In addition to these receptors, numerous studies have identified the presence of intracellular CBG (or transcortin) in the anterior pituitary corticotrope (de Kloet & McEwen 1976, Koch et al 1976. Pituitary transcortin binds corticosterone with high affinity, but unlike the corticosteroid receptors, does not translocate into the cell nucleus, effectively limiting the nuclear corticosterone signal (Sakly & Koch 1981, 1983.…”

Section: Introductionmentioning

confidence: 99%

Testosterone-dependent variations in plasma and intrapituitary corticosteroid binding globulin and stress hypothalamic-pituitary-adrenal activity in the male rat

Viau

Meaney²

2004

Journal of Endocrinology

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Hypothalamic-pituitary-adrenal (HPA) activity is governed by glucocorticoid negative feedback and the magnitude of this signal is determined, in part, by variations in plasma corticosteroid-binding globulin (CBG) capacity. Here, in gonadectomized male rats we examine the extent to which different testosterone replacement levels impact on CBG and HPA function. Compared with gonadectomized rats with low testosterone replacement ( 2 ng/ ml), plasma adrenocorticotropin and -endorphin/ -lipotropin responses to restraint stress were reduced in gonadectomized rats with high testosterone replacement ( 5 ng/ml). Plasma CBG levels also varied negatively as a function of testosterone concentration. Moreover, glucocorticoid receptor binding in the liver was elevated by higher testosterone replacement, suggesting that testosterone acts to enhance glucocorticoid suppression of CBG synthesis. Since pituitary intracellular CBG (or transcortin) is derived from plasma, this prompted us to examine whether transcortin binding was similarly responsive to different testosterone replacement levels. Transcortin binding was lower in gonadectomized rats with high plasma testosterone replacement ( 7 ng/ml) than in gonadectomized rats with low testosterone replacement ( 2 ng/ml). This testosterone-dependent decrease in pituitary transcortin was associated, in vitro, with an enhanced nuclear uptake of corticosterone. These findings indicate that the inhibitory effects of testosterone on corticotrope responses to stress may be linked to decrements in plasma and intrapituitary CBG. This could permit greater access of corticosterone to its receptors and enhance glucocorticoid feedback regulation of ACTH release and/or proopiomelanocortin processing.

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“…We have tentatively termed these the B-preferring sites, and have shown that they differ from previously described nonclassical glucocorticoid binding sites (6)(7)(8). Differentiation from classical glucocorticoid receptors has been achieved on the basis of steroid specificity, and the preferential occupation and nuclear translocation of classical glucocorticoid receptors by the in vivo administration of DM.…”

Section: Discussionmentioning

confidence: 89%

“…McEwen and his co-workers have shown tritiated corticosterone (3H-B) to be negligibly bound by pituitary nuclei in comparison with tritiated dexamethasone (3H-DM) (4,5). Intracellular or membrane bound CBG-like 'H-B sequestering sites have been proposed to account for this difference (6)(7)(8). However, despite the apparently very low levels of corticosterone retained in the nucleus, this steroid has been shown to suppress ACTH secretion from cultured mouse pituitary tumor AtT-20 cells (9).…”

Section: Introductionmentioning

confidence: 99%