A rapid assay for cholesterol side-chain desmolase and the quantitative determination of desmolase activity in adrenals.
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Adrenal Glands↗
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On the requirement for protein synthesis during corticotropin-induced stimulation of cholesterol side chain cleavage in rat adrenal mitochondrial and solubilized desmolase preparations.
Following simple homogenization, significant amounts of mitochondrial-derived, cholesterol side chain cleaving enzyme (desmolase) activity are recovered in rat adrenal 105 000 X g-supernatant fraction. Corticotropin administration enhances soluble desmolase activity, and cycloheximide potentiates this effect. The lipid droplet fraction which has no desmolase activity markedly enhances pregnenolone synthesis in the soluble desmolase preparations, presumably by supplying free cholesterol substrate. Corticotropin particularly with cycloheximide pretreatment, enhances lipid fraction activity. Thus increased cholesterol availability may largely explain the corticotropin effect on the soluble desmolase system. Since protein synthesis is required for corticotropin activity in intact mitochondria, but not in calcium-swollen mitochondria or the soluble enzyme system, the labile protein apparently required during corticotropin action may function to overcome a "barrier" which exists only in the intact mitochondria and restrains cholesterol side chain cleavage.
Adrenal Glands↗
The developmental changes in plasma adrenal androgens during infancy and adrenarche are associated with changing activities of adrenal microsomal 17-hydroxylase and 17,20-desmolase.
The plasma concentrations of dehydroepiandrosterone, androstenedione, and dehydroepiandrosterone sulfate decrease during the first year of life, remain low during childhood, and then increase during adrenarche. To determine whether alterations in adrenal enzyme activity might explain the changing secretory pattern of the adrenal androgens, we measured human adrenal microsomal 3 beta-hydroxysteroid dehydrogenase-isomerase, 17,20-desmolase, 17-hydroxylase, and 21-hydroxylase activities. 12 adrenals from individuals aged 3 mo to 60 yr were studied. The patients were divided into three groups based upon the age of the patient when the adrenal glands were obtained: group 1, infants aged 3--8 mo (n = 3); group 2, preadrenarchal or early adrenarchal children aged 2--9 yr (n = 4); and group 3, adults aged 20--60 yr (n = 5). The mean activity of the 17,20-desmolase, 17-hydroxylase, and 21-hydroxylase fell by 50% and that of 3 beta-hydroxysteroid dehydrogenase-isomerase activity rose 80% from group 1 to 2. A fourfold increase in 17,20-desmolase (P less than 0.002) and 17-hydroxylase (P less than 0.001) activity and a doubling in 21-hydroxylase activity (P less than 0.005) occurred between groups 2 and 3. We conclude that the decline in plasma adrenal androgens after birth appears to be associated with a rise in 3 beta-hydroxysteroid dehydrogenase-isomerase and a fall in 17,20-desmolase and 17-hydroxylase activity. The subsequent increase in plasma adrenal androgen concentration during adrenarche is coincident with a rise in 17,20-desmolase and 17-hydroxylase activity.
3-Hydroxysteroid Dehydrogenases↗
Effect of ketoconazole on human ovarian C17,20-desmolase and aromatase.
Ketoconazole, an imidazole antimycotic drug, inhibits steroid biosynthesis in adrenal and testicular tissue by blocking cytochrome P-450 dependent enzymes. To study the effect of ketoconazole on steroid biosynthesis in the human ovary we incubated human ovarian tissue (mainly theca cells) or granulosa cells with radiolabeled precursors and increasing concentrations of ketoconazole. After incubation, steroids were extracted and separated by thin layer chromatography (TLC). Activity of C17,20-desmolase and aromatase was estimated by measuring the amount of their radioactive products with liquid scintillation counting. After incubation of ovarian tissue with [3H]17-hydroxyprogesterone the production of [3H]androstenedione was reduced by increasing concentrations of ketoconazole (0-200 microM) to a minimum of 31% of basal production. This indicates a strong inhibition of ovarian C17,20-desmolase by ketoconazole with a 50% inhibiting concentration (IC50) of 23 microM. After incubation of human granulosa cells with ketoconazole (0-2000 microM) and [3H]androstenedione the production of [3H]estrone and [3H]estradiol was suppressed to minimally 37 and 35% of basal values, indicating a significant inhibition of ovarian aromatase. IC50-values were 105 microM ketoconazole for estradiol and 130 microM for estrone. In conclusion, ketoconazole was shown to inhibit human ovarian C17,20-desmolase and aromatase in vitro. As in human adrenals and testes ovarian C17,20-desmolase seems to be most sensitive to the inhibitory effect of ketoconazole.
17-alpha-Hydroxyprogesterone↗
Regulation of the activities of 17-hydroxylase and 17,20-desmolase in the human adrenal cortex: kinetic analysis and inhibition by endogenous steroids.
Kinetic analyses of 17-hydroxylase and 17,20-desmolase activities have been performed on human adrenal microsomes from 12 individuals, aged 1-60 yr. The median Michaelis constant of 17-hydroxylase for the substrate pregnenolone was 0.09 microM, and that of 17,20-desmolase for the substrate 17-hydroxypregnenolone was 0.12 microM. The median maximum velocity of 17-hydroxylase (0.25 nmol/mg X min) was significantly greater than that of the desmolase (0.13 nmol/mg X min). There was no significant correlation between the age of the adrenal donor and the Michaelis constant, but the maximum velocity for both activities in the single infant donor was lower than the values in older individuals. The inhibitory effects of various steroids on both enzyme activities also were studied. All steroids examined, except cortisol, competitively inhibited both enzymes. In each case the inhibition constant was higher for 17-hydroxylase than for 17,20-desmolase, indicating that C21 side-chain cleavage would be more sensitive to inhibition by endogenous steroids. The results, taken together with those of similar studies of 3 beta-hydroxysteroid dehydrogenase kinetics, are compatible with the suggestion that increased enzyme synthesis mediated by ACTH and differential inhibition by endogenous steroids may, in part, account for developmental changes in adrenal hormone secretion.
Adolescent↗
17,20-desmolase deficiency in a female newborn, paradoxically virilized in utero.
The patient was born with ambiguous genitalia (stade III of Prader). The karyotype revealed a normal female genotype. A defect in 21-hydroxylase, at first suspected, was denied by the hormonal studies. Indeed, extremely high levels of pregnenolone, pregnenolone sulfate, progesterone were found in association with low plasma levels of delta 4-androstenedione, testosterone, dehydroepiandrosterone and its sulfate, while cortisol 17OH-progesterone and ACTH levels and plasma renin activity were normal. The hormonal pattern was thus consistent with 17,20-desmolase deficiency. The dynamic studies further supported this contention: all the progestagens rose further after ACTH stimulation and were suppressed by dexamethasone. Meanwhile, all androgens failed to rise after ACTH: the responses of cortisol were normal. The in utero virilization of the female fetus was not understood until an history of virilization was allegedly found in the mother (luteoma of pregnancy). This is the first case of 17-20 desmolase defect recognized in a female newborn. This child, born with ambiguous genitalia had presented the concurrence of two very rare conditions. The in utero virilization of maternal origin enabled us to make the diagnosis of the 17-20 desmolase defect, which otherwise would have been ignored in a XX subject in the neonatal period because it would obviously be unsymptomatic at this age.
Adrenocorticotropic Hormone↗
Cofactor requirements of steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities in cell extracts of Clostridium scindens.
Two neutral steroid-transforming activities were demonstrated in cell extracts of Clostridium scindens. Steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase were found to be inducible in cells cultured in the presence of cortisol. Both activities required manganese ions and NAD+ or NADH for activity. Cortisol, cortisone and 11-desoxycortisol were substrates as well as inducers of steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities. 17 alpha-Hydroxyprogesterone was an effective inducer but did not serve as a substrate for either enzyme activity. C. scindens is the first bacterial species of the normal human intestinal flora reported to elaborate inducible steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities. The results of cofactor, substrate specificity and induction studies suggest that these two activities may reside in the same enzyme complex.
20-Hydroxysteroid Dehydrogenases↗
In vitro fertilization as a diagnostic and therapeutic tool in a patient with partial 17,20-desmolase deficiency.
OBJECTIVE: To present a case with 17,20-desmolase activity deficiency in which in vitro fertilization (IVF) served not only as a therapeutic approach but also as a diagnostic tool for the specificity of the enzymatic deficiency. DESIGN: IVF in the patient under study compared with a control group. All women treated with pure follicle-stimulating hormone (FSH). SETTING: IVF program at the Instituto Valenciano de Infertilidad. PATIENTS, PARTICIPANTS: A patient with primary amenorrhea, who was the subject under study, and seven normally cycling control patients undergoing IVF in the same series. INTERVENTIONS: IVF, steroidogenesis in vitro of granulosa-luteal cell obtained at ovum pick-up. MAIN OUTCOME MEASURE(S): Oocyte fertilization and embryo cleavage. Serum and follicular fluid (FF) levels of estradiol (E2), progesterone (P), testosterone (T), androstendione (A), 17 alpha-hydroxyprogesterone (17-OHP). In vitro accumulation of E2 and P. RESULTS: Ovulation induction with FSH was successful in achieving follicular development despite low circulating E2. Fertilization and cleavage rates were similar to the control subjects. The patient developed ovarian hyperstimulation. The lack of 17,20-desmolase activity was detected by normal P levels in serum and FF, high 17-OHP, and low T, A, and E2 levels in serum and FF. Granulosaluteal cell cultures in the presence of T restored normal E2 and P production in response to gonadotropins. CONCLUSIONS: In patients with 17,20-desmolase deficiency, follicular development, oocyte maturation, and fertilization can take place in a low estrogenic environment.
17-alpha-Hydroxyprogesterone↗
Combined 17-hydroxylase and 17,20-desmolase deficiencies: evidence for synthesis of a defective cytochrome P450c17.
We studied in vivo and in vitro steroidogenesis in six phenotypic female children with 17-hydroxylase deficiency. The diagnosis was suspected as a likely cause of familial low renin hypertension and was confirmed by findings of reduced basal and ACTH-stimulated serum and urinary levels of cortisol and other 17-hydroxysteroids, together with hypergonadotropic hypogonadism in both 46,XY and 46,XX patients, and abnormally increased secretion of 17-desoxysteroids, such as progesterone, 11-deoxycorticosterone, and corticosterone. ACTH stimulation testing demonstrated a lesser degree of 17-hydroxylase deficiency in the obligate heterozygous parents; one father had increased basal serum 17-hydroxyprogesterone values, unresponsive to ACTH, suggesting partial Leydig cell 17,20-desmolase deficiency. In vitro kinetic analysis of testicular microsomal enzymes in the affected 46,XY male pseudohermaphrodites confirmed that both 17-hydroxylase and 17,20-desmolase activities were less than 2% of those in age-matched normal subjects. However, in spite of this virtual absence of both enzymatic activities of cytochrome P450c17, Northern blot analysis demonstrated abundant amounts of RNA in these tests that hybridized to a cDNA specific for this P450 enzyme. Moreover, immunoblot analysis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis-resolved testicular microsomes showed an apparently normal content of an immunoreactive protein with a mol wt similar to that of authentic P450c17. These results suggest that these patients have a point mutation in the gene for P450c17; the mutant gene is transcribed, but gives rise to a protein defective in normal 17-hydroxylase and 17,20-desmolase activities.
Adrenal Hyperplasia, Congenital↗
Conversion from pure 17,20-desmolase- to combined 17,20-desmolase/17 alpha-hydroxylase deficiency with age.
A previously described phenotypically female 46,XY-individual with 17,20-desmolase deficiency was followed from adolescence to adulthood. While at age 16.9 years her 17 alpha-hydroxylating capacity was normal and steroids not hydroxylated in position 17 low, decreasing 17 alpha-hydroxylated and increasing unhydroxylated steroids were observed thereafter up to the age of 25.2 years. Simultaneously with the steroid changes, previously normal blood pressure (110/80 mmHg) increased (180/130 mmHg). Since 17 alpha-hydroxylation and 17,20-desmolase activity are regulated by one cytochrome P450-17 alpha, it is concluded that, in this same patient, 17 alpha-hydroxylase activity was normal during childhood and adolescence, but decreased in the young adult. 17,20-desmolase activity, by contrast, was completely absent already in the fetus, causing absence of masculinization. The factors modulating this difference in cytochrome P450-17 alpha activity with age are as yet unknown.
Adrenal Hyperplasia, Congenital↗
Cigarette smoke-induced cholesterol C-20, 22-desmolase inhibition in pregnancy.
In an attempt to demonstrate the physiological importance of cholesterol C-20, 22-desmolase regulation of pregnenolone formation in maternal cigarette smoking during pregnancy, the in vitro effect of cigarette smoke extract on corpus luteal and placental desmolase ability to cleave (26-14C) cholesterol to (14C) isocaproic acid, was studied. Using the reverse-isotope dilution technique, (14C) isocaproic acid was isolated and characterized. With the homogenates of corpora lutea of pregnancy (4 to 9 weeks gestation) the maximal inhibitory effect (98.3%) on desmolase efficiency became evident at equivalent of 4 cigarettes. In response to concentrations of the extract at 1/2, 1, 2 and 4 cigarette equivalents on the preparations of placentae (18 to 20 weeks gestation), a dose-dependent pattern of inhibitory effect was observed (29.1 to greater than 95.1%). These results are consistent with the interpretation that decreased supply of pregnenolone for the biosynthesis of progestational and oestrogenic hormones may be causally related to changes characteristic of cigarette-smoke induced pathologic state. It is suggested that similar studies directed towards alteration in biosynthetic capacity of steroidogenic enzymes may provide the basis for our understanding of molecular events initiated in response to the common insult.
Adult↗
Synthesis and evaluation of sulfur-containing glutethimide derivatives for aromatase and desmolase inhibitory activity.
Novel sulfur-containing glutethimide derivatives, substituted with either thiol or methylsulfide groups in the ortho/para positions of the aromatic ring, were synthesized and tested for both human placental aromatase and bovine adrenocortical desmolase inhibitory activities. The synthesis was achieved by the chlorosulfonation of gluthethimide, which yielded a 3:1 mixture of the para to ortho sulfonyl chlorides 2a/b. The sulfonyl chlorides of gluthethimide were reduced with Zn/H2SO4 to give the thioglutethimides 3a/b, which in turn were methylated with MeI/EtOH to give the corresponding methylsulfides 4a/b. In comparison to aminoglutethimide (AG), 3a/b and 4a/b were weak inhibitors of aromatase, with 3a/b being more potent than 4a/b. Aromatase inhibition by the thiol compound was pH-dependent; 3a/b was most potent at higher pH (7.4) than at lower (6.6). This suggested that the thiolate form of 4 coordinates with the ferric heme of aromatase. Likewise, both 3a/b were less potent at inhibiting bovine adrenal desmolase than AG. Possible reasons for the surprisingly poor aromatase inhibitor activity of these compounds are discussed.
Adrenal Cortex↗
Familial partial 17,20-desmolase and 17alpha-hydroxylase deficiency presenting as infertility.
PURPOSE: Females with 17alpha-hydroxylase/17,20-desmolase deficiency normally present with amenorrhea, sexual infantilism, hypertension, and hypokalemia. We report on a new clinical presentation of this combined enzymatic defect. METHODS: Four Jewish women from two unrelated families presented with primary infertility. All patients exhibited a normal phenotype, blood pressure, and serum potassium levels with abnormally high follicular phase serum progesterone and low E2 levels. In order to characterize the underlying defect, the following steps were undertaken: 1) ovarian suppression by GnRH agonist, 2) adrenal suppression by dexamethasone, 3) ovarian stimulation by gonadotropins, 4) adrenal stimulation by ACTH, 5) hormonal assessment of follicular fluid aspirates, and 6) assessment of in vitro E2 production by luteinized granulosa cells. RESULTS: The clinical characteristics and endocrine testing results support the diagnosis of a partial deficiency in 17alpha-hydroxylase/17,20-desmolase activities, shared by the adrenal gland and the ovaries CONCLUSIONS: Female infertility can be the first and sole clinical manifestation of this enzymatic defect. Its exact nature and prevalence remain to be determined.
Adrenal Glands↗
Male pseudohermaphroditism consistent with 17,20-desmolase deficiency.
A 16-year-old phenotypic female with XY genotype presented an unusual form of nonfamilial male pseudohermaphroditism. Seemingly a normal girl during childhood, the patient failed to undergo pubertal changes presenting with scant pubic hair, absent axillary hair, lack of breast development, retarded bone age and primary amenorrhea. Neither uterus nor adnexa were palpable above the blind-ending vagina. Serum testosterone and estradiol were barely detectable by radioimmunoassay, while LH and FSH reached castrate levels. Two small testes were removed from the pelvic sidewalls which, on biopsy, showed atrophy and hyalinization of seminiferous tubules, but clusters of Leydig cells without signs of hypertrophy or hyperplasia. Administration of testosterone resulted in urinary nitrogen retention and a decrease in serum LH and FSH. Radioimmunoassay of various serum or plasma steroids and gas chromatographic determination of urinary steroids prior to and following ACTH stimulation yielded results which permitted to rule out 20,22-desmolase, 3beta-hydroxysteroid dehydrogenase, 17-hydroxylase and 17beta-hydroxysteroid dehydrogenase deficiency. Low plasma dehydroepiandrosterone sulfate (DHEA-S) and androstenedione (delta4 A) concentrations, low urinary 17-ketosteroid and particularly low dehydroepiandrosterone (DHEA) excretion and the minimal rise of plasma DHEA-S and delta4 A and of urinary DHEA in response to ACTH in conjunction with a normal response of other serum and urinary C-21 steroids are consistent with 17,20-desmolase deficiency. Direct confirmation of this defect, however, seems impossible in the absence of in vitro studies of testicular steroidogenesis.
17-Ketosteroids↗
Two types of male pseudohermaphroditism due to 17, 20-desmolase deficiency.
Three patients with male pseudohermaphroditism due to 17,20-desmolase deficiency were studied at a pubertal age. Patients 1 and 2 (first cousins, raised as males) had inter-sexual external genitalia, some spontaneous male pubertal development, some response of plasma testosterone to hCG, low plasma dehydroepiandrosterone, and pregnanetriolone (3 alpha, 17 alpha, 20 alpha-trihydroxypregnan-11-one) in urine. Patient 3 (unrelated, raised as a female) had female external genitalia, no spontaneous pubertal development, no response of plasma testosterone to hCG, normal plasma dehydroepiandrosterone, and no pregnanetriolone in urine. It is concluded that two types of 17,20-desmolase deficiency exist: one with an incomplete defect in both, the delta 4- and the delta 5-pathway (patients 1 and 2), and one with a complete defect in the delta 4-pathway only (patient 3).
Aldehyde-Lyases↗
Marked attenuation of ultradian and circadian rhythms of dehydroepiandrosterone in postmenopausal women: evidence for a reduced 17,20-desmolase enzymatic activity.
Circulating levels of adrenal delta 5-androgens [dehydroepiandrosterone (DHEA), and its sulfate (DS)] selectively decrease with age in both sexes, while cortisol secretion remains unchanged. The mechanism(s) to account for this dissociation is unclear. We tested the hypothesis that a reduced enzymatic activity for delta 5-androgen biosynthesis may be responsible for this phenomenon by examining the ultradian and circadian rhythmicity (15-min sampling frequency for 24 h) of DHEA and cortisol and the responsiveness of DHEA, DS, and cortisol to human CRF stimulation and by the analysis of relative enzymatic activities in the biosynthesis of adrenal steroids in older postmenopausal women (PMW) and younger cycling women (NCW). Our data show that the timing of the circadian rhythm of DHEA secretion was not altered, but the acrophase amplitude was decreased (P less than 0.01) in aged PMW compared to NCW. While the pulse frequency of DHEA remained unchanged, the pulse amplitude was markedly attenuated in PMW compared with NCW (3.5 +/- 0.6 vs. 8.1 +/- 1.1 nmol/L; P less than 0.01). Correspondingly, the 24-h mean of DHEA was markedly reduced (P less than 0.001) in PMW (5.5 +/- 0.8 nmol/L) from that in NCW (12.1 +/- 1.4 nmol/L). For cortisol, all parameters were similar between the two groups. Thus, compared to NCW, the decline of circulating DHEA level in PMW was expressed by attenuations of pulse amplitude and circadian amplitude, without changes in the timing of the circadian rhythm or pulse frequency. Further, DHEA and DS, but not cortisol, responses to 8-h hCRF infusion were significantly (P less than 0.01) diminished in PMW. These findings together with decreased product/precursor ratios for DHEA/17-hydroxypregnenolone (P less than 0.01) and androstenedione/17-hydroxyprogesterone (P less than 0.05) suggest a reduction of 17,20-desmolase enzymatic activity in PMW compared to that in NCW. Steroid ratios for 3 beta-hydroxysteroid dehydrogenase and 17 alpha-hydroxylase were unaltered. We conclude from these preliminary data that the disparity of DHEA and cortisol secretion in aged PMW is probably related to an intraadrenal event, resulting from a decrease in 17,20-desmolase expression, which governs the biosynthesis of delta 5-adrenal androgen.
Adrenal Glands↗
Hypergonadotrophic hypogonadism in an XX female subject due to 17,20 steroid desmolase deficiency.
A 22 year old XX female patient with primary amenorrhoea and sexual infantilism was studied. Persistently elevated serum LH and FSH concentrations and exaggerated LRH pituitary responsiveness indicated deficient ovarian hormonal production. Serum levels of C21 and C19 steroids measured by specific radioimmunoassays before and after appropriate stimulations demonstrated an impairment of adrenal and ovarian steroid biosynthesis. Baseline levels of androstenedione (delta 4-A), testosterone (T), and oestradiol-17 beta (E2) were persistently below the normal range for healthy women at early follicular phase, whereas progesterone (P) and 17 alpha-OH-progesterone (17-OH-P) serum levels were significantly higher than those observed for normal women. Adrenal and gonadal stimulation with ATCH and hCG, respectively, resulted in a considerable rise in serum P and 17-OH-P without any significant change in circulating levels of delta 4-A, T, and E2. These findings were consistent with the diagnosis of 17,20 steroid desmolase deficiency at both adrenal and ovarian levels. This is the first report of a 17,20 desmolase deficiency in an XX individual, and is in line with previous suggestions that familial occurrence of the disorder would fit an autosomal recessive pattern of inheritance.
Adrenal Cortex Hormones↗
Mode of action of steroid desmolase and reductases synthesized by Clostridium "scindens" (formerly Clostridium strain 19).
A recently isolated hitherto unknown Clostridium from human feces, designated Clostridium "scindens" (formerly strain 19), synthesizes at least two enzymes active on the side-chain of the steroid molecule and two enzymes active on the hydroxyl groups of the 7-position of bile acids. Steroid desmolase, responsible for side-chain cleavage of corticoids, and 20 alpha-hydroxysteroid dehydrogenase have not been detected in any other bacterial species of the resident colonic flora. Steroid desmolase is Eh-dependent (optimum ca. -130 mV), requires a hydroxy group at C-17, and preferably an alpha-ketol group in the side-chain; an alpha-hydroxy group at C-20 reduces and a beta-hydroxy group at C-20 prevents side-chain cleavage. With suitable substrates, the yield of C-19 steroids is proportional to the bacterial multiplication rate. 20 alpha-Hydroxysteroid dehydrogenase (20 alpha-HSDH) is also Eh-dependent (optimum ca. -300 mV) and reduces the C-20 keto function to an alpha-hydroxy group, regardless of the presence or absence of a hydroxy group at C-17. 7 alpha-Dehydroxylase metabolizes cholic and chenodeoxycholic acid, while 7 beta-hydroxysteroid dehydrogenase acts upon ursodeoxycholic acid. The latter two enzymes are not specific for C. scindens.
Bile Acids and Salts↗