Long-term glucocorticoid concentrations as a risk factor for childhood obesity and adverse body-fat distribution.

BACKGROUND: Childhood obesity is an important risk factor for premature development of the metabolic syndrome (MetS) at adulthood. There is need for understanding of the mechanisms underlying the MetS and obesity. Patients with Cushing's disease suffer from similar metabolic complications, leading to the hypothesis that inter-individual cortisol variation may contribute to the onset of obesity. In addition, glucocorticoid receptor (GR)-gene polymorphisms resulting in differential glucocorticoid (GC) sensitivity, have been associated with an adverse metabolic profile. AIM: To study associations of GC levels in scalp hair, as a marker of long-term systemic GC concentrations, and genetically determined GC sensitivity with obesity and body-fat distribution in children. METHODS: We performed a cross-sectional study of cortisol and cortisone concentrations over a 3-month period, measured by LC-MS/MS (Liquid Chromatography Tandem Mass Spectrometry) in hair of 3019 6-year-old children participating in the Generation R study. Genotyping of GR-gene polymorphisms was performed. RESULTS: Of all children, 4.3% was obese and 13.4% overweight. Cortisol was significantly associated with risk of obesity (odd ratio (OR): 9.4 (3.3-26.9)) and overweight (OR: 1.4 (1.0-2.0)). Cortisone was associated with risk of obesity (OR: 1.9 (1.0-3.5)). Cortisol and cortisone were significantly positively associated with body mass index, fat mass (FM) index and android/gynecoid FM ratio. GR polymorphisms were not associated with adiposity parameters. CONCLUSION: Long-term cortisol concentrations are strongly associated with an increased risk of childhood obesity and adverse body-fat distribution. Future research may reveal whether these are causal relations and may be a target for therapy.

Polymorphisms in the glucocorticoid receptor gene and in the glucocorticoid-induced transcript 1 gene are associated with disease activity and response to glucocorticoid bridging therapy in rheumatoid arthritis.

Glucocorticoids (GC) are widely used in rheumatoid arthritis (RA). Ongoing active disease due to GC resistance may unfavorably influence long-term disease outcome in RA. We studied the association between the presence of glucocorticoid receptor (GR) and glucocorticoid-induced transcript 1 (GLCCI1) gene polymorphisms, which modulate GC sensitivity, and baseline disease activity score (DAS) and efficacy of GC bridging therapy in RA. We prospectively studied in vivo GC sensitivity in 138 patients with recent-onset or longstanding RA. In vivo GC sensitivity was expressed as the relative decrease in DAS following 2 weeks of standardized GC therapy. All patients were genotyped for the GR polymorphisms BclI (rs41423247), N363S (rs6195), 9ß (rs6198), ER22/23EK (rs6189 + rs6190), and the GLCCI1 variant rs37972 and subsequently divided in groups carrying a polymorphism associated with increased GC sensitivity (BclI-G allele, N363S-G allele, GLCCI1-C allele) or decreased GC sensitivity (9ß-G allele, ER22/23EK-A/A allele, GLCCI1-T allele). Differences in baseline DAS and relative decrease in DAS in the different genotype groups were analyzed using analysis of covariance and linear regression. Baseline DAS was higher in patients who carried polymorphisms of the GR and GLCCI1 genes associated with decreased GC sensitivity. GLCCI1 genotype, but not GR genotypes, was associated with improvement in DAS in male patients with RA. The GLCCI1 gene minor allele (rs37972) may be associated with less efficient GC bridging therapy in male RA patients. Carriers of the BclI-G, N363S-G, or GLCCI1-C alleles had lower levels of baseline disease activity, suggesting a role for the GLCCI1 and GR gene in regulation of GC sensitivity to endogenously produced cortisol.

Elevated hair cortisol concentrations in children with adrenal insufficiency on hydrocortisone replacement therapy.

BACKGROUND: Glucocorticoid replacement therapy in patients with adrenal insufficiency needs to be tailored to the individual patient based on body composition and clinical signs and symptoms as no objective method for assessment of treatment adequacy is available. Current treatment regimens are often not satisfactory, which is shown by the adverse metabolic profile and doubled mortality rates in treated adrenal insufficiency patients. Measurement of cortisol concentrations in hair reflect the long-term systemic cortisol exposure and may be of use in refinement of hydrocortisone treatment. OBJECTIVE: We aimed to study whether long-term cortisol (hydrocortisone) levels, as measured in scalp hair, are similar in children with adrenal insufficiency and healthy children. MATERIAL AND METHODS: We set up a case control study, measuring anthropometric characteristics and hair cortisol concentrations (HCC) in 54 hydrocortisone substituted children with adrenal insufficiency (AI patients) in the age of 4-18 years and 54 healthy children matched for gender and age. RESULTS: Mean HCC were significantly higher in AI patients compared with healthy controls (mean 13·3 vs 8·2 pg/mg, P = 0·02). AI patients also had a higher BMI (P < 0·001) and waist circumference (WC) (P = 0·02). HCC was significantly associated with BMI (P = 0·002) and WC (P = 0·002). HCC explained 13% of the difference in BMI and 29% of the difference in WC between AI patients and controls. CONCLUSION: Hydrocortisone-treated AI patients have increased HCC and adverse anthropometric characteristics compared with healthy controls. HCC measurement may be of value in identifying overtreatment and thereby improve hydrocortisone replacement therapy.

Long-term cortisol levels are not associated with nasal carriage of Staphylococcus aureus.

Staphylococcus aureus (S. aureus) colonizes the anterior nares in part of the population and the persistent carrier state is associated with increased infection risk. Knowledge concerning the determinants of S. aureus nasal carriage is limited. Previously, we found that glucocorticoid receptor polymorphisms influence carrier risk, suggesting involvement of glucocorticoids. Our aim was to study long-term cortisol levels in non-carriers, intermittent, and persistent carriers of S. aureus. We hypothesized that cortisol levels are higher in carriers, since cortisol-induced immune suppression would enhance S. aureus colonization. We determined nasal carrier state and long-term hair cortisol levels in 72 healthy subjects. Nasal swabs were collected twice with an interval of 2 weeks. Cortisol levels were determined in hair segments of 3 cm, which corresponds to a period of roughly 3 months. Of all 72 participants, 38 were non-carriers, 10 were intermittent carriers, and 24 were persistent carriers of S. aureus. Cortisol levels did not differ between these carrier groups (p=0.638). Long-term cortisol levels are not associated with S. aureus nasal carriage.

Working memory performance is associated with common glucocorticoid receptor gene polymorphisms.

Cortisol has a modulatory influence on cognitive functions in humans. Both impairing and enhancing effects of cortisol administration have been shown for hippocampus-dependent declarative memory, and impairing effects have been shown for prefrontal-cortex-dependent working memory function. Given the high density of glucocorticoid (GC) receptors in the prefrontal cortex, we investigated whether common polymorphisms of the GC receptor (GR) gene (ER22/23EK, N363S, BclI, 9 beta A3669G) modulate the influence of cortisol administration on working memory. Working memory performance was investigated in 169 subjects on 10 mg hydrocortisone (cortisol) and placebo using an item recognition task. No impairing effect of hydrocortisone treatment became evident. However, a sex x genotype interaction on general working memory performance was revealed (p = 0.02). While female heterozygous carriers of the 9 beta G allele displayed faster reaction times than the other genotype groups, 9 beta G heterozygous men were relatively slower. Heritability estimates for memory are roughly 50%, indicating that common genetic polymorphisms have an important impact on cognitive performance. Our results suggest that variants of the GR gene might explain some of the variance attributable to genetic factors. Furthermore, it can be speculated that they modulate the individual vulnerability for memory impairments related to stress-related psychiatric disorders.

Tissue mRNA expression of the glucocorticoid receptor and its splice variants in fatal critical illness.

BACKGROUND: Critical illness results in activation of the hypothalamic-pituitary-adrenal (HPA) axis, which might be accompanied by a peripheral adaptation in glucocorticoid sensitivity. Tissue sensitivity is determined by the active glucocorticoid receptor GRalpha, of which two splice variants involving the hormone-binding domain exist, GRbeta and GR-P. OBJECTIVE: To study tissue mRNA expression of the GR and its splice variants in fatal critical illness. DESIGN AND METHODS: We assessed mRNA expression of the GRalpha, GRbeta and GR-P variants in liver (n = 58) and muscle (n = 65) of patients who had died after intensive care, and had been randomized for insulin treatment. We analysed whether GR mRNA expression was associated with insulin treatment, cortisol levels and glucocorticoid treatment. RESULTS: GRalpha and GR-P mRNA constituted 87 +/- 8% and 13 +/- 2%, respectively, of total GR mRNA in liver. GRbeta mRNA could only be amplified in five liver samples. All variants were present in most muscle samples (alpha = 96 +/- 11%, P = 3.9 +/- 0.4%, beta = 0.010 +/- 0.002%). GR expression was not associated with insulin therapy. A strong positive relationship was observed between the different GR variants in both liver and muscle (P < 0.001 for all). Serum cortisol levels were negatively associated with liver GRalpha and muscle GR-P expression (P < 0.05). mRNA expression of both liver GRalpha and GR-P, but not muscle GR, was substantially lower in patients who had received exogenous glucocorticoids (P < 0.01). CONCLUSION: We demonstrate the presence of GRalpha and GR-P mRNA in liver and of GRalpha, GRbeta and GR-P mRNA in muscle, with no evidence for altered splicing in critical illness. In contrast to muscle GR, liver GR expression was substantially lower in patients receiving exogenous glucocorticoids.

Salivary cortisol is related to atherosclerosis of carotid arteries.

BACKGROUND: Dysregulation of the hypothalamic-pituitary-adrenal axis has been suggested as an independent risk factor for ischemic heart disease. The aim of our study was to evaluate whether two markers of the hypothalamic-pituitary-adrenal axis activity, the level of salivary cortisol and the diurnal salivary cortisol pattern, are associated with atherosclerosis of the carotid arteries in an elderly population. METHODS AND RESULTS: A total of 1866 participants of the Rotterdam Study, a population-based cohort study in the elderly, provided four salivary cortisol samples throughout 1 d, and underwent ultrasonography to examine the presence of plaques in the common, internal, and bifurcation sites of both carotid arteries. Two summary measures of the separate cortisol values were computed: area under the curve (AUC), which is a measure of total cortisol exposure while awake; and the slope, which is a measure of diurnal cortisol decline. RESULTS: Total cortisol exposure while awake (AUC) was associated with higher plaque scores (beta = 0.08 per sd of AUC, 95% confidence interval 0.00-0.16; P = 0.04) in a fully adjusted linear regression model. Persons with an AUC in the highest tertile had a higher number of plaques of carotid arteries compared with those in the lowest tertile (3.08 vs. 2.80, 95% confidence interval of difference 0.09-0.48; P = 0.005). There was no relation between diurnal cortisol decline and plaque score. CONCLUSION: Our results support the hypothesis that increased total cortisol exposure is independently associated with atherosclerosis of the carotid arteries.

Glucocorticoid receptor gene polymorphisms associated with more aggressive disease phenotype in MS.

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system, in which unknown environmental factors are thought to trigger disease in genetically susceptible persons. Glucocorticoids (GCs) play an important role in controlling chronic inflammatory diseases, like MS. Three polymorphisms in the glucocorticoid receptor (GR) gene (N363S, ER22/23EK and the Bcl I C/G) have been shown to alter glucocorticoid sensitivity, and therefore may influence disease course. We investigated the influence of these polymorphisms on clinical and MRI parameters. The ER22/23EK polymorphism was associated with a more aggressive MS phenotype, measured both clinically and on MRI.

Effects of progesterone on the response to epidermal growth factor and other growth factors in cultured human meningioma cells.

The presence of receptors for progesterone in a large proportion of human meningioma tissues is well established. The occurrence of increased rates of growth of meningiomas in situ during pregnancy suggests the existence of a relationship between high progesterone levels and the growth of meningiomas. However, experiments with cultured meningioma tissue (cells or explants) have shown only minimal effects of progesterone. It has been shown recently that many meningiomas have receptors for epidermal growth factor. In this paper we have investigated the response of cultured human meningioma cells to epidermal growth factor and other growth factors and the modulation of this response by progesterone and the progesterone-receptor blocking agent mifepristone (RU 38486). The results suggest that the presence of progesterone in the culture medium increases the sensitivity of meningioma cells to mitogenic stimuli, whereas mifepristone can counteract the stimulating effects of progesterone.

Distribution and biochemical characterization of somatostatin receptors in tumors of the human central nervous system.

Fifty-two brain tumors, consisting of 17 astrocytomas, 4 oligodendrogliomas, 20 glioblastomas, 3 neurinomas, 2 ependymomas, 1 neurofibroma, 1 ganglioneuroblastoma, 1 medulloblastoma, 1 plexus papilloma, 1 teratoma, and 1 germinoma, were tested for their content of specific somatostatin receptors using autoradiographic techniques or in vitro binding assays with membrane homogenates. Somatostatin receptors were found in most of the differentiated glia-derived tumors such as astrocytomas and oligodendrogliomas whereas the poorly differentiated glioblastomas were usually free of receptors. Tumors originating from neuroblasts, i.e., ganglioneuroblastoma and medulloblastoma, contained a high density of somatostatin receptors, whereas neurinomas and neurofibromas as well as the ependymomas, one teratoma, and one plexus papilloma were lacking such receptors. In one germinoma, low amounts of somatostatin receptors were observed over the lymphocytic elements. Receptor-positive tumors had saturable and high affinity receptors with pharmacological specificity for somatostatin and somatostatin analogues resembling that of normal human central nervous system tissue. In most instances, they could be labeled with two different iodinated radioligands, a somatostatin octapeptide derivative (204-090) or a somatostatin-28 analogue. This is the first time that somatostatin receptors have been shown to exist not only on neuronal structures of the central nervous system but also on glial elements. The precise function of such somatostatin receptors on glial cells, which may be different from neurotransmission, remains to be determined.

Familial and iatrogenic cortisol receptor resistance.

A family is described in which the father, a daughter, and two sons had cortisol receptor resistance. Hirsutism, skull baldness, and menstrual irregularities existed only in the female patient, while all three males were asymptomatic. The syndrome was transmitted via a dominant autosomal trait. A lowered dexamethasone affinity and a lowered number of glucocorticoid receptors were detected on the peripheral mononuclear leukocytes of the female patient. Chronic administration of the glucocorticoid receptor-blocking agent mifepristone (RU 38486) to normal individuals resulted in resetting of the hypothalamo-pituitary-adrenal axis at a higher level, while the diurnal rhythm of cortisol and the responsiveness to corticotropin releasing factor remained present. In four postmenopausal women this resulted in a considerable increase in circulating androstenedione levels (and eventually of estradiol levels). This iatrogenic RU 38486-induced biochemical syndrome is similar and difficult to differentiate from familial cortisol receptor resistance. Among a group of patients with so-called "idiopathic hirsutism," four patients were recognized with elevated androstenedione and (slightly) elevated cortisol levels which showed abnormalities in the affinity and/or number of glucocorticoid receptors on their peripheral mononuclear leukocytes. Therefore it is hypothesized that the syndrome of (partial) glucocorticoid receptor resistance is far more common than currently thought, especially among the group of patients with so-called "idiopathic hirsutism."

Desensitization and resensitization of rat pituitary tumor cells in long-term culture to the effects of the somatostatin analogue SMS 201-995 on cell growth and prolactin secretion.

Cultured cells, prepared from the transplantable rat prolactin (rPRL)-secreting rat pituitary tumor 7315b were found to be inhibited in a dose-dependent way in their cell growth and hormone secretion by the somatostatin analogue SMS 201-995 (Sandostatin). In short-term (1 week) experiments these effects were not time dependent and of similar magnitude (an inhibition of approximately 50% at 100 nM SMA 201-995) both for the rate of rPRL secretion and for the rate of incorporation of tritiated thymidine into the tumor cells. When freshly isolated 7315b cells were used for long-term experiments (38 days), continuous exposure to SMS 201-995 at all concentrations tested (0.1 nM, 10 nM, and 1 microM) resulted in desensitization of the cells to the peptide with respect to rPRL secretion. Using a stable cell line derived from the long-term experiment and designated 7315c, we show that (a) long-term exposure of 7315c cells to SMS 201-995 leads to loss of sensitivity with respect to both rPRL secretion and cell growth, (b) this loss of sensitivity is accompanied by complete disappearance of the somatostatin receptors from the cells, (c) withdrawal of treatment from desensitized cells leads to reappearance of receptors and of sensitivity to SMS 201-995, showing that selection for a non-receptor-bearing population was not the cause of desensitization, and (d) since these experiments were carried out with a pure population of 7315c cells the effects of SMS 201-995 are direct effects on these cells and not effects mediated by other cell or organ systems.

Expression in hematological malignancies of a glucocorticoid receptor splice variant that augments glucocorticoid receptor-mediated effects in transfected cells.

Glucocorticoids play an important role in the treatment of a number of hematological malignancies, such as multiple myeloma. The effects of glucocorticoids are mediated through the glucocorticoid receptor alpha, the abundance of which can be modulated by alternative splicing of the glucocorticoid receptor mRNA. Two splice variants of the glucocorticoid receptor mRNA have been described: glucocorticoid receptor beta, which reportedly has a dominant negative effect on the actions of the glucocorticoid receptor alpha, and glucocorticoid receptor P, of which the effects are unknown. In this study, we have investigated the expression levels of these two splice variants at the mRNA level in multiple myeloma cells and in a number of other hematological tumors. Although the glucocorticoid receptor beta mRNA was, if at all, expressed at very low levels, considerable amounts (up to 50% of the total glucocorticoid receptor mRNA) glucocorticoid receptor P mRNA was present in most hematological malignancies. In transient transfection studies in several cell types and in multiple myeloma cell lines, the glucocorticoid receptor P increased the activity of the glucocorticoid receptor alpha. These results suggest that the relative levels of the glucocorticoid receptor alpha and the glucocorticoid receptor P may play a role in the occurrence of glucocorticoid resistance in tumor cells during the treatment of hematological malignancies with glucocorticoids.

Socioeconomic status in children is associated with hair cortisol levels as a biological measure of chronic stress.

INTRODUCTION: Low socioeconomic status (SES) may be associated with a high risk of lifestyle-related diseases such as cardiovascular diseases. There is a strong association between parental SES, stress and indicators of child health and adult health outcome. The exact mechanisms underlying this association have not yet been fully clarified. Low SES may be associated with chronic stress, which may lead to activation of the hypothalamic-pituitary-adrenal (HPA)-axis, resulting in a higher circulating level of the stress hormone cortisol. Therefore, chronic stress may mediate the association between low SES and elevated cortisol levels and its adverse outcomes. AIM: We investigated whether SES was associated with a chronic measure of cortisol exposure in a child population. METHODS: Cortisol and cortisone were measured in scalp hair in 270 children and adolescents, aged 4-18 years, enrolled through school visits. Neighborhood level SES was based on a score developed by the Netherlands Institute for Social Research using postal codes, and this includes neighborhood measures of income education and unemployment. Maternal and paternal education level were used as indicators of family SES. RESULTS: Neighborhood level socioeconomic status score was significantly associated with hair cortisol (ß=-0.103, p=0.007, 95%CI [-0.179, -0.028]) and hair cortisone (ß=-0.091, p=0.023, 95%CI [-0.167, -0.015]), adjusted for age and sex. Additionally, hair cortisol was significantly correlated with maternal education level and hair cortisone was significantly correlated with paternal education level. CONCLUSION: The results of our study suggest that the widely shown association between low family SES and adverse child health outcomes may be mediated by chronic stress, given the chronically higher levels of cortisol in children and adolescents in families with low SES. It is especially notable that the association between SES and cortisol was already found in children of young age as this can have major consequences, such as increased risk of cardio metabolic diseases in later life.

Acetoacetate is a cholesterogenic precursor for myelinating rat brain and spinal cord. Incorporation of label from [3-14C]acetoacetate, [14C]glucose and 3H2O.

Rat pups, 3 weeks old, were injected i.p. with combinations of 3H2O and either [3-14C]acetoacetate or [14C]glucose. 3H/14C incorporation ratios were measured in lipid fractions of homogenates and myelin prepared from whole brain and spinal cord. Spinal cord synthesized at least twice as much fatty acids and 3-fold more sterols than whole brain. Both tissues used acetoacetate preferentially for sterol synthesis, whereas label from [14C]glucose was distributed between fatty acids and sterols in the same way as 3H from 3H2O. The relative contributions of acetoacetate to sterol synthesis in whole tissue and in the purified myelin fraction were about the same, both for the cerebrum and for the spinal cord.

Preferential utilization of ketone bodies for the synthesis of myelin cholesterol in vivo.

1. The distribution of radioactivity among lipid classes of myelin and other subcellular brain fractions of young rats (18-21 days) was determined after in vivo injection of (3-(14)C-labelled ketone bodies, [U-(14)C] glucose or [2-(14)C] glucose. 2. The incorporation ratios (sterol/fatty acids) were 0.67, 1.48, 0.25, 0.62 and 0.54 for whole brain, myelin, mitochondria, microsomes and synaptosomes, respectively, with (3-(14)C)-labelled ketone bodies as substrate and 0.37, 0.89, 0.19, 0.34 and 0.29 with [U-(14)C] glucose as substrate. These data show that, both in whole brain and in subcellular brain fractions, acetyl groups derived from ketone bodies are used for sterol synthesis to a large extent than acetyl groups originating from glucose. 3. The specific radioactivity of cholesterol is much higher in myelin than in whole brain or in the other brain fractions, particularly after administration of labelled ketone bodies as substrate. 4. The incorporation patterns of acetoacetate and D-3-hydroxybutyrate were very similar, indicating that both ketone bodies contribute acetyl groups for lipid synthesis via the same metabolic route. 5. Our data suggest that a direct metabolic path from ketone bodies towards cholesterol exists - possibly via acetoacetyl-CoA formation in the cytosol of brain cells - and that this process is most active in oligodendrocytes.

Effects of triiodothyronine on the synthesis of sulfolipids by oligodendrocyte-enriched glial cultures.

Glial cultures were obtained from the brains of 1-week-old rats and were grown in a chemically defined, serum-free medium. We investigated the development of oligodendrocytes in these cultures and the synthesis of sulfolipids in the presence and absence of triiodothyronine (T3) in the medium: (1) In the presence of T3, the incorporation of [35S]sulfate into sulfolipids exhibited a developmental profile which is comparable to that found in the developing brain in vivo. A sharp peak of sulfolipid synthesis was observed at day 5 in vitro, which is equivalent to day 12 after birth. As observed in vivo, the percentage of label incorporated into sulfogalactosyldiradylglycerols decreased with time in culture. (2) Addition of T3 to the medium stimulated sulfolipid synthesis by oligodendrocytes in a dose-related manner (optimal T3 concentration, 30 nM). The hormone also enhanced the rates of cholesterogenesis and lipogenesis but to a lesser extent than sulfolipid synthesis. (3) The temporary omission of T3 from the medium resulted in lower rates of sulfolipid synthesis that could not be restored by readdition of T3. This inhibitory effect was most pronounced if the hormone was omitted from the medium on days 2 and 3 in culture. (4) Omission of T3 also resulted in the development of fewer oligodendrocytes in the cultures. Our results show that T3 is essential for the development of oligodendrocytes in our neurone-free culture system. They also indicate that the stimulation of myelination by thyroid hormones can, at least partially, be explained as a direct effect of T3 on oligodendrocytes, independent of an effect of T3 on neuronal growth.

Acetoacetate and glucose as substrates for lipid synthesis by rat brain oligodendrocytes and astrocytes in serum-free culture.

We have compared glucose and acetoacetate as precursors for lipogenesis and cholesterogenesis by oligodendrocytes and astrocytes, using mixed glial cultures enriched in oligodendrocytes. In order to differentiate between metabolic processes in oligodendrocytes and those in astrocytes, the other major cell type present in the mixed culture, we carried out parallel incubations with cultures from which the oligodendrocytes had been removed by treatment with anti-galactocerebroside serum and guinea-pig complement. The following results were obtained: 1. Both oligodendrocytes and astrocytes in culture actively utilize acetoacetate as a precursor for lipogenesis and cholesterogenesis. 2. In both cell types, the incorporation of acetoacetate into fatty acids and cholesterol exceeds that of glucose by a factor of 5-10 when the precursors are present at concentrations of 1 mM and higher. 3. Glucose stimulates acetoacetate incorporation into fatty acids and cholesterol, whereas acetoacetate reduces the entry of glucose into these lipids. This suggests that glucose is necessary for NADPH generation, but that otherwise the two precursors contribute to the same acetyl-CoA pool. 4. Both with acetoacetate and with glucose as precursor, oligodendrocytes are more active in cholesterol synthesis than astrocytes. 5. Using incorporation of 3H2O as an indicator for total lipid synthesis, we estimated that acetoacetate contributes one third of the acetyl groups and glucose one twentieth when saturating concentrations of both substrates are present.

Long-term treatment with RU486 and glucocorticoid receptor resistance: theoretical and therapeutic implications.

Glucocorticoid receptor resistance in humans occurs rarely in hereditary disorders. RU486 blocks progesterone receptors, but at higher doses also blocks glucocorticoid receptors. In this article, the clinical and biochemical effects of long-term treatment with RU486 of patients with meningiomas, breast cancer, and Cushing's syndrome are compared with those present in patients with hereditary glucocorticoid receptor resistance. The potential use of RU486 outside the field of fertility regulation is discussed.

Differential hormone-dependent transcriptional activation and -repression by naturally occurring human glucocorticoid receptor variants.

The molecular mechanisms underlying primary glucocorticoid resistance or hypersensitivity are not well understood. Using transfected COS-1 cells as a model system, we studied gene regulation by naturally occurring mutants of the glucocorticoid receptor (GR) with single-point mutations in the regions encoding the ligand-binding domain or the N-terminal domain reflecting different phenotypic expression. We analyzed the capacity of these GR variants to regulate transcription from different promoters, either by binding directly to positive or negative glucocorticoid-response elements on the DNA or by interfering with protein-protein interactions. Decreased dexamethasone (DEX) binding to GR variants carrying mutations in the ligand-binding domain correlated well with decreased capacity to activate transcription from the mouse mammary tumor virus (MMTV) promoter. One variant, D641V, which suboptimally activated MMTV promoter-mediated transcription, repressed a PRL promoter element containing a negative glucocorticoid-response element with wild type activity. DEX-induced repression of transcription from elements of the intercellular adhesion molecule-1 promoter via nuclear factor-kappaB by the D641V variant was even more efficient compared with the wild type GR. We observed a general DEX-responsive AP-1-mediated transcriptional repression of the collagenase-1 promoter, even when receptor variants did not activate transcription from the MMTV promoter. Our findings indicate that different point mutations in the GR can affect separate pathways of gene regulation in a differential fashion, which can explain the various phenotypes observed.