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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the chronic effects of alpha-melanocyte-stimulating hormone (alpha-MSH) on aldosterone secretion, synthetic alpha-MSH (8 micrograms/day) was infused in Sprague-Dawley rats by miniosmotic pumps for 5 days. Saline was infused in equivalent volume for 5 days using the same type of pumps in the control group of rats. Aldosterone secretion from the capsular cells of the two groups was examined in the basal state and in response to various stimuli of aldosterone secretion. Aldosterone secretion in vitro from the alpha-MSH-treated rats was significantly impaired in response to all stimuli tested including cyclic AMP, suggesting an intracellular defect in aldosterone synthesis in that group. These results are similar to those observed after chronic adrenocorticotropin administration.
Steroids
PMID:Impaired aldosterone secretion from dispersed adrenal capsular cells of chronically alpha-MSH-treated rats. 303 59

3 beta-Hydroxy-5-androsten-17-one is converted to 5-androstene-3, 17-dione by rat liver alcohol dehydrogenase (ADH). We have reported on the purity of the enzyme which is eluted with pyrazole as a single homogeneous protein using an AMP-agarose affinity column. Rat liver ADH can oxidize hydroxyl groups not only at 3 beta-, but also at 3 alpha-, and 17 beta-positions to a lesser extent; thus it is a pure mammalian enzyme with multifunctional activity for steroids. Since it does not contain delta 5-isomerase activity, the reaction of the dehydrogenase to form the delta 5-ketosteroid intermediate can be observed at pH 7.0, 25 degrees C. Similarly, intermediary product, 5-pregnene-3,20-dione, can be isolated in the conversion of pregnenolone by ADH to progesterone. With buffer alone in a cuvette, a non-enzymatic isomerization of the delta 5-3-ketone occurs at a slow rate (t 1/2 = 6 hrs) but occurs rapidly during isolation procedures. The delta 5-3-ketosteroid intermediates were identified by their behavior on TLC plates with UV light and by their characteristic spectra in the NMR.
Steroids 1982 Nov
PMID:Formation and isolation of delta 5-3-ketosteroids using a purified rat liver alcohol dehydrogenase. 622 30

Plasma testosterone levels before and after a single injection of hCG were significantly lower in 24-month old rats than 60--90 day old animals (p less than 0.001). Even with repeated hCG administration for three weeks, plasma testosterone levels of old rats could not be restored to levels present in unstimulated young rats. In response to in vitro LH and 8-bromo-cyclic AMP stimulation, purified young Leydig cells produced significantly higher amounts of testosterone than Leydig cells from old rats. Maximal testosterone formation of the young Leydig cells in response to LH was 42.0 +/- 6.88 ng/10(6) cells, while cells from old rats produced only 16.8 +/- 3.69 ng/10(6) cells (p less than 0.01). However, the dose of LH at which one half maximal response (ED50) occurred was 0.1 mIU/ml for young Leydig cells and 0.05 mIU/ml for old Leydig cells. Basal and 1.0 mIU LH-stimulated cyclic AMP formation were comparable in both groups, but cyclic AMP formation in response to 10 mIU of LH was significantly less in the old rats (p less than 0.05). Present results demonstrate impaired steroidogenic capacity of old rats both in vivo and in vitro. Decreased testosterone response in old rats most likely is the consequence of understimulation of Leydig cells by gonadotropin; however, there appear to be additional intrinsic defects in old Leydig cells.
Steroids 1980 Jun
PMID:The aging Leydig cell: 1. Testosterone and adenosine 3',5'-monophosphate responses to gonadotropin stimulation in rats. 625 Feb 54

The present in vitro studies using interstitial cells of adult rat testes demonstrated that ethanol inhibits LH- and 8-bromo-cyclic AMP-stimulated testosterone synthesis, pregnenolone- and progesterone-stimulated testosterone synthesis, and basal testosterone synthesis. However, the patterns of inhibition following exposure to 0.22 to 880 or 1100 mM ethanol were different. In general, the inhibition curves for LH-, 8-bromo-cyclic AMP-, pregnenolone- and progesterone-stimulated testosterone synthesis were biphasic, with a gradual slope from 0.22 to 220 mM ethanol, and a sharper slope with concentrations of ethanol greater than 220 mM. Basal testosterone synthesis was reduced only to 74% of control with ethanol concentrations up to 44 mM, and higher concentrations of ethanol reduced testosterone synthesis no further. The effect of ethanol on Lh-stimulated cyclic AMP accumulation showed an even different pattern: some of the lower concentrations of ethanol inhibited cyclic AMP accumulation, while higher levels of ethanol progressively increased cyclic AMP accumulation. These studies demonstrate that isolated interstitial cells are highly sensitive to the direct effects of ethanol; they also suggest that the principle site of ethanol inhibition may be at the level of the smooth endoplasmic reticulum where progesterone is converted to testosterone.
Steroids 1980 Nov
PMID:Direct inhibition of testosterone synthesis in rat testis interstitial cells by ethanol: possible sites of action. 625 26

Estrogen secretion and estrogen synthetase (aromatase) activity are stimulated in human trophoblast cells (JAr line) after addition of 1 mM dibutyryl cyclic AMP plus 1 mM theophylline (dbT) to the growth medium. The data given here show that (a) the aromatase specific activity in homogenized cells increases linearly over a 96 hr incubation period after addition of dbT; (b) addition of inhibitors of macromolecular synthesis, cycloheximide or actinomycin D, to the culture medium at the time of addition of dbT abolishes the stimulation of aromatase activity; (c) mixing dbT-grown cells, containing increased aromatase activity, with control cells does not result in an aromatase specific activity higher than the expected average, suggesting that dbT-grown cells do not contain a factor present in excess which serves to stimulate aromatase in control cells; and (d) NADPH, included in vitro in the aromatase assay or incubated with the cells for 48 hr as well as being present in the aromatase assay, has no stimulatory effect on aromatase specific activity in homogenized cells.
Steroids 1981 Jan
PMID:Macromolecular synthesis is required for stimulation of estrogen synthetase activity by dibutyryl cyclic AMP plus theophylline in choriocarcinoma cell culture. 626 25

Using metrizamide gradient centrifugation two populations of Leydig cells were found in both 60-90 day-old and 24 month-old rats. Cells from both Band 2 (B2) and Band 3 (B3) responded to LH stimulation with increased cyclic AMP formation; however, only B3 cells produced significant amounts of testosterone. Cells from both B2 and B3 of the old rats synthesized less cyclic AMP and testosterone than cells from their younger counterparts. In response to LH stimulation, 0.01 - 1.0 mIU/ml, no appreciable difference of cyclic AMP formation could be detected between young and old Leydig cells. Maximal testosterone production occurred when 1 mIU/ml LH was used. Only when LH concentration was increased to 10 and 100 mIU/ml, did young Leydig cells produce significantly more cyclic AMP than old Leydig cells. After addition of 5X10(-7)M of pregnenolone or progesterone to the incubation medium, both young and old Leydig cells produced comparable amounts of testosterone. These results demonstrate no impairment of old rat Leydig cells to synthesize testosterone from pregnenolone and progesterone.
Steroids 1981 Jan
PMID:The aging Leydig cell: 2. Two distinct populations of Leydig cells and the possible site of defective steroidogenesis. 626 26

Transformation of a steroidogenic mouse adrenal cell line (Y-1) by simian adenovirus SA7 produced a cell line with low apparent steroidogenic activity. The effect of ACTH and cholera toxin on cyclic AMP production was similar in both not transformed and virus-transformed cells and activity of cyclic AMP-dependent protein kinase was also similar in both cells. In transformed cells, cholesterol was metabolized to delta 5-3 beta-hydroxysteroids, mainly 20 alpha-dihydropregnenolone while in not transformed cells, the major metabolites were delta 4-3 ketosteroids (20 alpha-dihydro- and 11 beta-hydroxy-20 alpha-dihydroprogesterone). In both cell lines ACTH increased the metabolism of cholesterol. Further studies with labelled pregnenolone and progesterone revealed a loss of delta 5-3 beta-hydroxysteroid dehydrogenase/isomerase and 11 beta-hydroxylase activity in the transformed cells.
Steroids 1981 Mar
PMID:Modification of steroidogenesis in a mouse adrenal cell line (Y-1) transformed by simian adenovirus SA-7. 626 49

Interstitial cells derived from intact immature rats were cultured as monolayers. Their response to gonadotropins was evaluated by radioimmunoassay of 3',5'-cyclic AMP and steroids in the medium. Steroids were measured either directly (testosterone and progesterone) or after previous oxidation and thin layer chromatographic purification of the steroid extracts (4-androstene-3,17-dione, 5 alpha-androstane-3,17-dione, progesterone, 5 alpha-pregnane-3,20-dione). It could be demonstrated that these cells respond to gonadotropins with increased secretion of C19- and C21-steroids for at least 10 days. The total amount of steroids secreted in the medium, however, decreases markedly. During the first days of culture C19-steroid production falls dramatically whereas the secretion of C21 derivatives increases. A major fraction of the extracted steroids has undergone 5 alpha-reduction. A characteristic feature of cultured interstitial cells is the bell-shaped profile of the dose-response curve for gonadotropin stimulated androgen production. This profile is the result of a steroidogenic lesion situated at the level of the 17 alpha-hydroxylase and/or 17,20-desmolase and induced by high concentrations of gonadotropins. Daily changes with medium supplemented with LH or FSH, initiated on day 3 of culture, prevent a further loss of steroidogenic potential, restore the ability to produce C19-derivatives, and tend to normalize the dose-response curve for gonadotropin stimulated production of androgens.
 ...
PMID:Androgen and progestogen production in cultured interstitial cells derived from immature rat testis. 629 Jul 87

The long-term effects of dibutyryl cyclic AMP [(Bu)2-cAMP] on steroidogenesis in bovine adrenocortical cells maintained in primary culture were investigated. During the first 36 h, total steroid production by cells incubated with (Bu)2-cAMP increased progressively. Thereafter, however, there was a marked fall in steroid output. During the first 36 h adrenocortical cells incubated in the presence of (Bu)2-cAMP produced substantially more C19-steroids and 17 alpha-hydroxylated C21-steroids than did cells incubated in the absence of (Bu)2-cAMP. By 48 h, however, such steroid secretion by cells incubated in the continued presence of (Bu)2-cAMP declined toward control levels. By contrast, the secretion of corticosterone and 11-deoxycorticosterone was consistently less by cells maintained in the presence of (Bu)2-cAMP than by cells maintained in its absence. These results suggest that refractoriness results, at least in part, from events which occur distal to the formation of cAMP. The action of ACTH and (Bu)2cAMP to promote the secretion of 17 alpha-hydroxylated C21-steroids and C19-steroids, on the other hand, appears to reflect an increase in the rate of cholesterol side-chain cleavage, as well as an increase in 17 alpha-hydroxylase and possibly also 17, 20-lyase activities.
Steroids 1983 Feb
PMID:Steroidogenic refractoriness of bovine adrenocortical cells to dibutyryl cyclic AMP. 631 99

The molecular and species specificity of glucocorticoid suppression of corticosteroidogenesis was investigated in isolated adrenocortical cells. Trypsin-isolated cells from male rat, domestic fowl and bovine adrenal glands were incubated with or without steroidogenic agents and with or without steroids. Glucocorticoids were measured by radioimmunoassay or fluorometric assay after 1-2 h incubation. Glucocorticoids suppressed ACTH-induced steroidogenesis of isolated rat cells with the following relative potencies: corticosterone greater than cortisol = cortisone greater than dexamethasone. The mineralocorticoid, aldosterone did not affect steroidogenesis. Suppression by glucocorticoids was acute (within 1-2 h), and varied directly with the glucocorticoid concentration. Testosterone also suppressed ACTH-induced steroidogenesis. Glucocorticoid-type steroids have equivalent suppressive potencies, thus suggesting that these steroids may induce suppression at least partly by a common mechanism. Although corticosterone caused the greatest suppression, testosterone was more potent. The steroid specificity of suppression of cyclic AMP (cAMP)-induced and ACTH-induced steroidogenesis were similar, suggesting that suppression is not solely the result of interference with ACTH receptor function or the induction of adenylate cyclase activity. Exogenous glucocorticoids also suppressed ACTH-induced steroidogenesis of cells isolated from domestic fowl and beef adrenal glands, thus suggesting that this observed suppression may be a general mechanism of adrenocortical cell autoregulation.
Steroids 1983 Jun
PMID:Steroid control of steroidogenesis in isolated adrenocortical cells: molecular and species specificity. 632 May 2


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