Aminoglutethimide

A method to separate radiolabelled urinary estrogens by high performance liquid chromatography (HPLC) is described. Estrogen glucuronides were isolated from the urine of women receiving bolus injections of [4-14C]estrone or [4-14C]estradiol by adsorption on Sep-Pak C18 cartridges and subsequent DEAE Sephadex A25 column chromatography. Following enzyme hydrolysis, free estrogens were extracted and concentrated in methanol-water containing ascorbic acid. HPLC was performed either by C18 reversed phase chromatography using different concentrations of acetonitrile with or without tetrahydrofurane in phosphate buffer or methanol-water as mobile phases, or on a Diol column using chloroform-isooctane-n-hexane or isopropanol-isooctane-n-hexane as mobile phases. 3H-labelled estrogens were added as internal standards, and urinary [14C]estriol, [14C]estradiol and [14C]estrone concentrations could be measured with an interassay coefficient of variation less than 5%. Interassay coefficients of v...

Background: Major depressive disorder affects a substantial percentage of the US population, and can be highly debilitating. Selective serotonin reuptake inhibitors are commonly prescribed to treat depression, but may not be as effective for more severe or persistent ...

The pyridylglutarimide 3-ethyl-3-(4-pyridyl)-piperidine-2,6-dione (PyG) is a novel inhibitor of aromatase that was shown to cause effective suppression of plasma oestradiol levels in postmenopausal patients. In four patients receiving oral doses of PyG (500 mg) twice daily for 3–4 days, oestradiol levels fell to 31.1%±6.3% of baseline values within 48 h and remained suppressed during treatment. Of a further six patients who received oral PyG (1 g) as a single dose, five had quantifiable oestradiol levels. Oestradiol suppression was sustained for 36 h and recovery correlated with a fall of PyG concentrations below a threshold value of ca. 2 μg/ml. The pharmacokinetics of PyG were non-linear and, when fitted to the integrated Michaelis-Menten equation, yielded good parameter estimates forC o (21.7±1.82 μg/ml),K m (2.66±0.68 μg/ml) and Vmax (0.86±0.06 μg ml−1 h−1). On subsequent repeated dosing with PyG, both theK m (4.31±0.48 μg/ml) and the Vmax (1.83±0.13 μg ml−1 h−1) values increased and recovery from oestradiol suppression was more rapid, indicating that PyG induces its own metabolism.

The endocrine effects of 125 mg (low dose) aminoglutethimide (AG) twice daily (b.d.) were compared with those of 125 mg AG + 20 mg hydrocortisone (HC) b.d. in 23 and 45 postmenopausal patients with advanced breast cancer, respectively. The patients in each group were drawn from two separate populations, but the mean age and weight of the groups were similar and there were no significant differences between the pretreatment serum levels of the hormones investigated. Serum oestrone and oestradiol levels were suppressed by both treatments, but there was a significantly greater suppression by AG + HC. This greater suppression is probably due to the observed increase in serum androstenedione (i.e. precursor) levels with AG alone, whilst with AG + HC these levels were found to be reduced. In terms of suppression of serum oestrogen levels it is of benefit to combine low dose AG with HC.

To define the nature of the lesion of the early steroidogenic pathway (prior to pregnenolone formation) in gonadotropin-induced desensitization of rat testicular Leydig cells, we evaluated cholesterol side-chain cleavage activity in isolated mitochondria by measurement of pregnenolone synthesis and [14C]isocaproic acid formation from [26-14C]cholesterol. The enzyme activity was shown to be reduced after in vivo treatment with 10 micrograms hCG when compared to that of mitochondria from control animals only when measured in the presence of limiting NADPH concentrations (100 microM). Sonication of mitochondria from control and hCG-treated rats caused complete loss of cholesterol side-chain cleavage activity. When acetone-powdered adrenal cell mitochondria were employed as the source of the enzyme, the addition of sonicated Leydig cell mitochondria from control and hCG-treated animals caused the same differences as those observed with intact Leydig cell mitochondria in the presence of ...

To identify and prioritize chemicals that may alter steroidogenesis, an in vitro screening assay based on measuring alterations in hormone production was developed using the H295R human adrenocortical carcinoma cell line. Previous studies indicated that this cell line was useful to screen for effects on gene expression of steroidogenic enzymes. This study extended that work to measure the integrated response on production of testosterone (T), estradiol (E2), and progesterone/pregnenolone (P) using an ELISA. Under optimized culture and experimental conditions, the basal release of P, T and E2 into the medium was 7.0+/-1.2 ng/ml, 1.6+/-0.4 ng/ml, and 0.51+/-0.13 ng/ml, respectively. Model chemicals with different modes of action on steroidogenic systems were tested. Exposure to forskolin resulted in dose-dependent increases in all three hormones with the greatest relative increase being observed for E2. This differed from cells exposed to prochloraz or ketoconazole where P concentrati...

... L HARRIS, DPHIL, MRCP, lecturer in medicine ROBIN STUART-HARRIS, MRCP, lecturer ... MS, FRCS, consultant surgeon HARVEY WHITE, MCH, FRCS, consultant surgeon CLIVE L HARMER ... FRCS, consultant surgeon Correspondence and requests for reprints to: Dr IE Smith. ...

The hypothalamic-pituitary-adrenal axis is hyporesponsive to stress in late pregnancy, exemplified as reduced adrenocorticotropic hormone (ACTH) and corticosterone responses to restraint, but the mechanisms are unknown. We investigated forward drive and negative feedback upon the hypothalamic-pituitary-adrenal axis in pregnant rats. Corticotropin-releasing hormone (CRH) and vasopressin mRNA expression in the parvocellular paraventricular nucleus and mineralocorticoid and glucocorticoid receptor expression in the paraventricular nucleus and hippocampus were quantified with in situ hybridization. Because it can enhance the corticosterone negative feedback signal, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) bioactivity in these brain regions and anterior pituitary was measured in vitro, and ACTH and corticosterone stress responses were measured after intracerebroventricular glycyrrhetinic acid, an 11beta-HSD inhibitor. Changes in corticosterone feedback on ACTH secretion were examined after pharmacological adrenalectomy by metyrapone and aminoglutethimide. Parvocellular paraventricular nucleus CRH mRNA content was reduced on day 21 and the CRH mRNA : vasopressin mRNA ratio was unaltered, indicating decreased production of both CRH and vasopressin. An increase in glucocorticoid receptor mRNA expression in the dentate gyrus (mineralocorticoid receptor mRNA expression was unaltered) and increased 11beta-HSD1 activity in the paraventricular nucleus and anterior pituitary suggest an increase in slow negative feedback mechanisms in pregnancy, but glycyrrhetinic acid did not modify the stress response. After metyrapone/aminoglutethimide treatment, corticosterone decreased ACTH secretion more slowly in pregnancy, indicating a decrease in rapid feedback sensitivity. Thus, reduced forward drive rather than increased effectiveness of glucocorticoid negative feedback may underlie stress hyporesponsiveness of the hypothalamic-pituitary-adrenal axis in pregnancy.

Inhibition of postmenopausal estrogen production by aromatase inhibitors is an established drug treatment modality for postmenopausal breast cancer. In this article postmenopausal estrogen disposition and the alterations caused by treatment with aromatase inhibitors are reviewed. Recent investigations have challenged the hypothesis that aromatization of androstenedione into estrone is the sole production pathway for estrogens in postmenopausal women. The finding that estrogens persist in the plasma of patients receiving aminoglutethimide treatment despite a near total inhibition of the aromatase enzyme suggests that alternative pathways for estrogen synthesis exist. While nonspecific actions of aromatase inhibitors may be disadvantageous, certain effects may also be beneficial. Recent findings that aminoglutethimide may induce estrone sulfate metabolism questions whether this "prototype" aromatase inhibitor might have a dual mechanism of action. The importance of investiga...

There exists evidence that body mass index (BMI) impacts on the efficacy of aromatase inhibitors in patients with breast cancer. The relationship between BMI and the efficacy of tamoxifen is conflicting. We investigated the impact of BMI on the efficacy of single tamoxifen and tamoxifen plus an aromatase inhibitor in the well-defined prospective study population of the ABCSG-06 trial. ABCSG-06 investigated the efficacy of tamoxifen vs tamoxifen plus aminoglutethimide in postmenopausal women with hormone receptor-positive breast cancer. Taking BMI at baseline, patients were classified as normal weight (BMI=18.5-24.9 kg m(-)(2)), overweight (BMI=25-29.9 kg m(-)(2)), and obese (30 kg m(-)(2)) according to WHO criteria. Overweight+obese patients had an increased risk for distant recurrences (hazard ratio (HR): 1.51; Cox P=0·018) and a worse overall survival (OS; HR: 1·49; Cox P=0·052) compared with normal weight patients. Analysing patients treated with single tamoxifen only, no differe...