Showing papers on "Steroid biosynthesis published in 1983"

The effect of ketoconazole on steroidogenesis in cultured mouse adrenal cortex tumor cells

Abstract: The effects of the antimycotic agent ketoconazole on steroid biosynthesis in adrenal cells was investigated in monolayer cultures of functional mouse adrenal cortex tumors. Ketoconazole inhibits ACTH-stimulated steroidogenesis to below non-stimulated levels at concentrations of 1.0 μg/ml or higher. Half maximal inhibition occurs at a concentration of 0.3 μg/ml. These drug levels are in the therapeutic range achieved by oral administration in human subjects. The inhibitory effects of 3.3 μg/ml or less of ketoconazole are totally reversible within the first hour after removal of the agent. Exposure of the cultures to high concentrations of ketoconazole for periods of 24–48 hours is not toxic to the cells, with a resumption of steroidogenic activity within several hours after its removal. Cyclic AMP-stimulated steroidogenesis is also inhibited by this agent, but it has no effect on ACTH-stimulated cAMP production in these cultures. Ketoconazole is an even more potent inhibitor of 11β hydroxylation in these c...

Androgenic modulation of cyclic adenosine monophosphate (cAMP)-dependent meiotic arrest.

Abstract: This study investigated further our previous finding that testosterone synergizes with dibutyryl cyclic AMP (dbcAMP) to arrest the meiosis of a very high proportion of cumulus-enclosed (intact) pig oocytes in vitro, suggesting that estradiol may have mediated in this synergism. The effects of androgens [testosterone (T), 0.5 MM; dihydrotestosterone (DHT), 0.5 MMI, estradiol (E2), 0.5 MM, gonadotropins [NIH follicle-stimulating hormone (FSH), 0.1 to 10 pg/mI; highly purified (hp) FSH, 0.1 pg/mI; luteinizing hormone (hpLH), 30 ng/mlJ, and dbcAMP, 1 mM, on the maturation of liberated intact or cumulus-free (denuded) oocytes were investigated. In one series of experiments, intact oocytes were cultured in medium containing T with NIH-FSH (10 pg/mI) with or without the steroid biosynthesis inhibitor, cyanoketone (0.7 X 10” M). After culture for 6 to 48 h, oocytes were air dried for cytogenetic analysis, the meiotic stage was scored and in some cases spent media were analyzed by radioimmunoassay for E3 and progesterone (P4) content. After 24 h of culture, FSH and dbcAMP similarly and significantly arrested meiosis of intact oocytes (45% and 43% matured, respectively), but the arresting actions of these compounds were modulated quite differently by androgen; that of dbcAMP was significantly enhanced by T, while that of FSH was significantly depressed by both T and DHT. Nevertheless, FSH with T transiently maintained meiotic arrest since a very high proportion of oocytes remained at the germinal vesicle (GV) stage after 12 h of culture, compared with controls (95% and 45% at GV stage, respectively). No difference was detected between impure NIH-FSH and hpFSH relative to the meiotic progression of intact oocytes and hpLH with T did not duplicate the arresting actions of either FSH preparation. This transient arresting action of FSH with T was mediated by the adherent cumulus cells since the maturation of denuded oocytes was not affected by FSH, T or FSH with T. While substitution of T with E3 did not duplicate this cumulus cell-mediated androgenic effect, the modulations exerted by DHT on either dbcAMP- or FSH-induced meionc arrest were not as marked as those exerted by T. Furthermore, analysis of E2 and P4 in the spent media of intact oocytcs cultured for 6 or 12 h in the presence of FSH with T revealed positive correlations between the proportion of immature oocytes and the E2 :P4 ratio in the media. Compared with controls, meiotic arrest was maintained for up to 24 h in medium containing cyanoketone with T and FSH, and positive correlations were established between the proportion of GV oocytes and the E2 P4 ratio in the spent media. These results indicate that androgens have the capacity to modulate cyclic AMP-dependent meiotic arrest in vitro and suggest that the expression of this modulation may be regulated by the aromatase system and/or the Ea :P4 status of the adherent cumulus cells. These findings are considered in light of the two currently popular hypotheses regarding the mechanisms which control meiotic maturation.

Hypercholesterolemia due to Elevated Low Density Lipoprotein-Cholesterol in Newborns with Anencephaly and Adrenal Atrophy

Abstract: In the present investigation, we evaluated the relationship between plasma lipoprotein-cholesterol and adrenal steroid production in abortuses and newborns in whom the adrenal was expected to be atrophic, i.e. in anencephalics. We found that umbilical cord plasma levels of dehydroepiandrosterone sulfate (DS) in 23 anencephalics delivered between 13.5 and 45.5 weeks of gestation (mean +/- SE, 176 +/- 37 ng/ml) were significantly lower than those in normal newborns of similar gestational ages; the umbilical cord plasma concentrations of cortisol in many anencephalics, however, were within normal limits. The levels of total cholesterol (134 +/- 10 mg/dl) and low density lipoprotein (LDL)-cholesterol (94 +/- 8 mg/dl) were substantially higher (up to 4-fold) in umbilical cord plasma of anencephalics than in umbilical cord plasma of normal newborns. The mean level of high density lipoprotein-cholesterol in umbilical cord plasma of anencephalic abortuses and newborns (38 +/- 4 mg/dl) was approximately 50% higher than that in normal newborns. The lowest plasma cholesterol level (56 mg/dl) and a concentration of DS (480 ng/ml) that was among the highest seen in the group of anencephalics were found in an anencephalic newborn in whom adrenals were of near-normal weight. Plasma cholesterol levels were inversely correlated to adrenal weights and plasma DS levels, and plasma DS levels were correlated to adrenal weight. Whereas the estimated plasma pool of DS in normal newborns increased to over 300 micrograms during the latter part of gestation, that of anencephalic newborns was much lower (less than 1 to 26 micrograms) and did not appear to increase as a function of gestational age. Conversely, the estimated plasma pool of cholesterol in normal newborns appeared to decline slightly during the last 10 weeks of gestation (80 mg at term), whereas that of anencephalic newborns expanded greatly near term; levels (approximately 200 mg) were attained that were about 3 times those in normal newborns. We conclude that the hypercholesterolemia in anencephalic newborns, due primarily to extremely elevated plasma levels of LDL-cholesterol, is a result of decreased uptake and utilization of plasma LDL-cholesterol for steroid biosynthesis by the adrenals. Since hypercholesterolemia is apparently early in gestation in anencephalic abortuses, we speculate that in normally developing fetuses, plasma LDL-cholesterol is used as substrate for adrenal steroidogenesis early in gestation as well as near term when the rates of growth and steroid production by the adrenals accelerate markedly.

Inborn errors of steroid biosynthesis: detection by a new mass-spectrometric method.

Abstract: A new mass-spectrometric technique relies on ionization during bombardment of the analyte (dissolved in a liquid matrix, usually glycerol) by an atom beam (e.g., Ar0, Xe0). This technique, termed "fast atom bombardment," is particularly useful in the characterization of polar charged molecules. A neutral beam is not essential, and a primary beam of cesium ions has been successfully used to produce spectra equivalent to those obtained by fast atom bombardment. In this communication I report data on the use of both ion and atom primary beams for producing secondary-ion mass spectra of conjugated steroids. In negative-ion spectra produced for steroid glucuronides and sulfates, the ion [M - H]- is invariably the major high-mass peak, and the lack of substantial fragmentation allows assay of relatively complex mixtures if the analytes differ in mass. I describe here the use of secondary-ion mass spectrometry for distinguishing, by urinary steroid analysis, patients with the four enzyme defects that can affect cortisol synthesis: defects in 17 alpha-hydroxylase, 3 beta-hydroxysteroid dehydrogenase/isomerase, 21-hydroxylase, and 11 beta-hydroxylase.

Structural studies of metyrapone: a potent inhibitor of cytochrome P-450.

Abstract: The crystal and molecular structure of metyrapone, a powerful inhibitor of certain cytochromes P-450, is described. Cytochrome P-450 enzymes are involved in metabolic processes, including those activating insecticides, drugs, and carcinogens. Metyrapone inhibits both the adrenal cytochrome P-450 catalyzing 11-beta-hydroxylation in steroid biosynthesis and most microsomal cytochromes P-450 induced by phenobarbital pretreatment. Crystal data are as follows: a = 11.828 (1), b = 6.268 (6), c = 18.269 (3) A, beta = 115.27 (1) degree, V = 1224.9 (3) A3, space group P21/c, dcalcd = 1.227 g cm-3, Z = 4. No intermolecular interactions are apparent in the solid state other than van der Waals forces. The torsion angle about the C(7)-C(10) bond to which the two 3-pyridyl groups are attached is 59.4 (1) degree. The three negatively charged heteroatoms form a triangle; the nitrogen atoms are anti to the exocyclic oxygen and are 4.347 (1) A apart. The N5-O11 distance is 5.850 (1) A; the N14-O11 intramolecular distance is 4.750 (1) A. The "twisted butterfly" conformation found for metyrapone is found in other molecules that are substrates and inducers of the specific cytochrome P-450 inhibited by metyrapone. The availability of nucleophilic functional groups is a feature common to most directly acting inhibitors of cytochrome P-450 enzymes and is manifested in metyrapone by the presence of the basic nitrogens. These factors may be necessary for interaction with the protein.

Gonadal Sources of the Posterior Pituitary Hormones

Abstract: Publisher Summary The actions of oxytocin and related peptides on the reproductive system are achieved via the release from the neurohypophysis into the peripheral circulation; however, the ovary itself may be a major source of oxytocin in some species and raises the possibility that oxytocin can act as a local hormone within the gonads. Both oxytocin- and vasopressin-related neurophysins indicate that synthesis of these neuropeptides may occur in the testis, as well as the ovary. The primary roles of gonadal oxytocin and vasopressin remain undetermined although several possibilities warrant serious consideration. Both hormones can stimulate the contraction of the smooth muscle of the male and female reproductive tracts, and they can, therefore, play a role in processes such as egg transport and spacing or sperm transport. Oxytocin releases PGF 2α , from the uterine endometrium of the ewe, and is probably involved in the control of luteolysis in this species. The most exciting possibility, which has been suggested by recent in vitro data, is that these peptides may provide a local feedback control system on steroid biosynthesis within the gonad.

Metabolic Errors of Adrenal Steroidogenesis

Abstract: Publisher Summary This chapter discusses several disorders of steroid biosynthesis and describes their hormonal and clinical manifestations as well as the current methods of diagnosis and treatment. It presents a spectrum of 21-hydroxylase deficiencies, which exist with differing degrees of severity of enzyme deficiency. Congenital adrenal hyperplasia (CAH) is a family of inherited disorders of adrenal steroidogenesis. The three main classes of hormones synthesized by the adrenal cortex are mineralocorticoids, glucocorticoids, and sex steroids. Aldosterone secretion is primarily regulated via the rennin–angiotensin system, which is responsive to the state of electrolyte balance and plasma volume. The genes for human leukocyte antigens, cell surface antigens important in transplantation, are located on the sixth chromosome. The virilization that is caused by CAH can be remedied by the surgical correction of the ambiguous genitalia, but the decision to do so must take into account an assessment of the patient's potential for future sexual function and fertility.

The pituitary and testis : clinical and experimental studies

Abstract: 1 Patterns of Secretion and Metabolism of the Gonadotrophic Hormones- 11 Assay Methods- 111 Human FSH, LH and Prolactin- 112 Animal Gonadotrophins- 12 Patterns of LH and FSH Secretion in Normal Men- 13 Metabolic Clearance and Gonadotrophin Secretion Rates in Normal Men- 131 MCR and Production Rate of LH- 132 MCR and Production Rate of FSH- 133 Initial Clearance of Gonadotrophin Subunits- 134 Effect of Renal Disease on MCR- 14 Summary- 2 Control of FSH and LH Secretion- 21 Sites of Production of FSH and LH- 22 Hypothalamic Influences on FSH and LH Secretion- 23 Influence of Testicular Feedback- 231 Feedback Control of LH- 232 Feedback Control of FSH- 24 Assays for Inhibin- 241 Modified Steelman-Pohley Bioassay- 242 Bioassays Using Castrate Rams- 243 Bioassays In Vivo Using Rodents- 244 In Vitro Bioassays for Inhibin- 25 Assay Specificity- 26 Sources of Inhibin- 27 Evidence for Inhibin from Immunisation Studies- 28 Characteristics and Mode of Action of Inhibin- 29 Physiological Implications of Inhibin- 210 Summary- 3 Pituitary Testicular Axis During Pubertal Development- 31 Studies in Men- 311 Changes During Fetal Life- 312 Changes in the Newborn- 313 Changes During Childhood and Adolescence- 314 Pituitary Responses to LHRH- 32 Studies in Rats- 321 Changes in LH, FSH and Testosterone Concentrations with Age- 322 Relationship Between Age and Hormonal Levels- 323 Changes in Testicular Histology with Age- 324 Significance of Hormonal Changes in the Developing Rat- 33 Studies in Rams- 331 Changes in FSH, LH, Prolactin and Testosterone Concentrations with Age- 332 LH, FSH and Testosterone Responses to LHRH with Age- 333 Changes in Testicular Histology with Age- 334 Significance of Hormonal Changes- 34 Overall Comments- 4 Changes in the Pituitary-Testicular Axis with Age- 41 Introduction- 42 Methods- 421 Testing the Pituitary-Testicular Axis- 422 Selection of Subjects- 423 Statistical Methods- 43 Summary of Results- 431 Virility, Testicular Size and Histology- 432 Gonadotrophin and Sex Hormone Levels- 433 Metabolic Clearance and Production Rates of Sex Steroids- 434 Dynamic Tests of Gonadotrophin and Testosterone Secretion- 44 Significance of Senescent Testicular Degeneration- 441 Mechanism of Hormone Changes with Age- 442 Further Studies- 443 Aetiology of Testicular Damage- 45 Clinical Relevance- 46 Summary- 5 Spermatogenesis and the Sertoli Cell- 51 Spermatogenesis- 511 The Spermatogenic Cycle- 512 Kinetics of the Spermatogenic Process- 513 Duration of Spermatogenesis- 514 Requirements for Quantitation of Spermatogenesis- 52 The Sertoli Cell- 521 Morphological Characteristics- 522 Nucleus- 523 Cytoplasm- 524 Inter-Sertoli Cell Junctions- 525 Sertoli Cell Maturation- 526 Secretory Products- 5261 Seminiferous Tubule Fluid- 5262 Androgen-Binding Protein- 5263 Inhibin- 5264 Plasminogen Activator- 5265 Other Secretory Products- 527 Steroidogenic Activity- 528 Hormonal Regulation of Sertoli Cell Function- 529 Actions of FSH on the Sertoli Cell- 5210 Effects of Androgen on the Sertoli Cell- 5211 Biochemical Changes Associated with Sertoli Cell Maturation- 6 Leydig Cell Function- 61 Introduction- 62 Morphology of the Leydig Cell- 63 Steroid Biosynthesis and Secretion- 64 Regulation of Leydig Cell Function- 65 Hormonal Regulation of LH Receptors- 651 LHRH and Leydig Cell Function- 66 Leydig Cells and Spermatogenesis- 67 Androgens in Blood- 68 Abnormalities of Leydig Cell Function- 681 Congenital Disorders- 682 Acquired Disorders- 6821 Cirrhosis of the Liver- 6822 Chronic Renal Failure- 6823 Age- 683 Testicular Disorders- 7 The Effect of Testicular Damage on Sertoli and Leydig Cell Function- 71 Introduction- 72 Spermatogenic Damage and the Control of FSH Secretion- 73 Sertoli Cell Function and Testicular Damage- 74 Luteinising Hormone, Testosterone and Spermatogenic Damage- 75 Leydig Cell Structure and Spermatogenic Damage- 76 Leydig Cell Function and Testicular Damage- References

Effects of beta-naphthoflavone administration to pregnant rats on steroid hormone biosynthesis and metabolism in ovarian microsomes.

Abstract: Administration of low doses of beta-naphthoflavone (beta-NF) to pregnant rats on days 7 to 14 of gestation has been associated with extensive fetal mortality. Studies were conducted to evaluate the effects of beta-NF administration on several extrahepatic cytochrome P-450-dependent enzymes responsible for steroid biosynthesis in the ovary. Pregnant rats received beta-NF (15 mg/kg) for 2-, 4- or 6-day periods before study on day 15 of gestation. At this stage of pregnancy no adverse effects on maternal weight gain, percent resorptions or fetal body weight were observed after beta-NF treatment. Cytochrome P-450 content of ovarian microsomes was not altered by beta-NF treatment. Estrogen biosynthesis in ovarian microsomes (aromatase activity), assayed as conversion of [14C]testosterone to 17 beta-estradiol, was increased nearly 2-fold in the beta-NF-treated dams. Incubation of ovarian microsomes with [14C]progesterone yielded 20 alpha-hydroxy progesterone and an unidentified compound as major products. There was no evidence of cytochrome P-450-dependent conversion of progesterone to androgens at this stage in pregnancy. In contrast to the effects of beta-NF on aromatase activity, progesterone catabolism was unaltered after administration of beta-NF for a 4-day period. The absence of a change in 20 alpha-hydroxy steroid dehydrogenase activity suggests that corpus luteum function is unaltered after beta-NF exposure. These data indicate that beta-NF administration during midgestation is associated with a selective alteration in in vitro ovarian steroidogenesis and further suggest a mechanism for beta-NF related in utero toxicity.

A new synthetic route for preparing 14C-labelled aminogutethimide

Abstract: A new route for preparing aminoglutethimide labelled at C5 (Scheme I (10)) with 14C is described, which offers the advantage of introducing 14C at a late stage in the synthesis.

Effects of drugs associated with hyperprolactinemia on plasma steroids and on steroid receptors and metabolism in human breast cancer.

Abstract: Certain commonly taken pharmaceutical preparations induce increased levels of plasma prolactin. The effects of these drugs on (a) tumor steroid receptors and metabolism, and (b) plasma hormones and hormone binding proteins have been studied in postmenopausal women with breast cancer. Two groups have been compared, 18 patients on drug treatment for at least 2 months and 15 subjects with no history of drug ingestion. Patients taking medication had significantly higher levels of plasma prolactin compared with control women. No significant difference was observed between the groups with regard to the plasma concentrations of dehydroepiandrosterone (DHA) and its sulphate (DHS), testosterone, estrone, estradiol-17β, sex hormone binding globulin (SHBG), and albumin. Similarly, no difference was observed between these two groups with regard to estrogen receptor (ER), progestogen receptor (PR), or androgen receptor (AR) levels in the tumors nor their ability to metabolize (7−3H) testosterone. It is considered that the ingestion of these drugs does not affect tumor mechanisms involving steroids.