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Results for “20-alpha-Dihydroprogesterone”

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At least 19 recordsLinked to original sources
PubMed1979

Interrelationships of circulating maternal steroid concentrations in third trimester pregnancies. III. Effect of intravenous cortisol infusion on maternal concentrations of estriol, 16 alpha-hydroxyprogesterone, 17 alpha-hydroxyprogesterone, progesterone, 20 alpha-dihydroprogesterone, delta 5-pregnenolone, delta5-pregnenolone sulfate, dehydroepiandrosterone sulfate, and cortisol.

The effect of a large dose (1000 mg) of iv cortisol-hemisuccinate on circulating steroid concentrations in five women, 28--34 weeks, gestational age, is reported. Maternal concentrations of estriol, 16 alpha-hydroxyprogesterone, 17 alpha-hydroxyprogesterone, progesterone, 20 alpha-dihydroprogesterone, delta 5-pregnenolone, delta 5-pregnenolone sulfate, dehydroepiandrosterone sulfate, and cortisol were measured by RIA before and at 8 and 12 h after iv cortisol infusions at 0 and 8 h. Data were evaluated by repeated measure analysis of variance. Estriol and 17 alpha-hydroxyprogesterone suppressed initially (P less than 0.05) and suppressed further with retreatment and increased treatment time (P less than 0.05). Dehydroepiandrosterone sulfate and progesterone suppressed initially (P less than 0.05) but did not suppress further with retreatment and increased treatment time (P greater than 0.05). delta 5-Pregnenolone and delta5-pregnenolone sulfate increased initially (P less than 0.05) but did not increase further (P greater than 0.05). Concentrations of 16 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone were unchanged by cortisol infusion initially (P greater than 0.1) and with retreatment and increased treatment time (P greater than 0.1).

20-alpha-Dihydroprogesterone↗
PubMed1978

Progesterone metabolism in cultured amniotic fluid cells.

Amniotic fluid cells obtained by amnicentesis at 16-20 weeks' gestation were grown in culture until a confluent monolayer of cell had been formed. Radiolabeled pregnenolone, progesterone and 20 alpha-dihydroprogesterone were added to the cell cultures; steroid metabolites which formed after 24 and 48 hours of incubation were identified. Incubation of the cell cultures with pregnenolone-3H resulted in the formation of progesterone, 17alpha-progesterone and 20 alpha-dihydroprogesterone. A significant amount of progesterone was identified after incubating the cell cultures with 20 alpha-dihydroprogesterone. The results indicate that 3 beta-ol-dehydrogenase, 17 alpha-hydroxylase and 20 alpha-hydroxysteroid dehydrogenase enzymes are present in cultured amniotic fluid cells obtained at 16-20 weeks' gestation.

20-alpha-Dihydroprogesterone↗
PubMed1975

Progesterone concentration in placenta, molar tissue, and ovarian theca lutein cyst.

Progesterone concentrations in 2 full-term normal placentas, molar tissue from 3 cases of hydatidiform mole were measured by competitive protein binding. Sephadex LH-20 column chromatographic separation of extracts from these tissues showed that, in placental and molar tissue, 85 to 95% of the extracts were progesterone and very small amounts of 20 alpha-dihydroprogesterone and 17 alpha-hydroxyprogesterone. The concentration of progesterone in the placenta were 368.8 and 317.2 ng/g tissue, respectively, while in molar tissue the concentration were 2474.5, 1974.6, and 4146.0 ng/g tissue, respectively. Progesterone concentration in ovarian tissue was between 1121;2 and 1440.9 ng/g tissue. It is suggested that the high concentration of progesterone in molar tissue reflects functional capacity of the abnormal trophoblast in progesterone synthesis and accumulation of progesterone due to absence of a fetus. The lower concentration of progesterone in the ovary in molar pregnancy would appear to suggest that the ovary is a secondary source of progesterone in molar pregnancy.

Chorionic Gonadotropin↗
PubMed1978

Modification of vascular responsiveness to angiotensin II in pregnant women by intravenously infused 5alpha-dihydroprogesterone.

In gravid women who are destined to develop pregnancy-induced hypertension (PIH), normal pregnancy-associated refractoriness to the pressor effects of administered angiotensin II (A-II) is lost several weeks before the onset of hypertension. From a study of the determinants of A-II pressor responsiveness in normal gravid women, it appears likely that the loss of resistance to A-II is principally unrelated to plasma renin activity or to plasma A-II levels. However, it recently has been shown that the vascular refractoriness to A-II in normal women can be reduced significantly by the administration of the prostaglandin synthetase inhibitors, indomethacin or aspirin. In seven women who had developed PIH and who had lost their refractoriness to A-II, the infusion of 5alpha-pregnan-3,20-dione (5alpha-DHP) was associated with restoration of refractoriness to the pressor effects of A-II. Moreover, in five normotensive gravid women beyond 28 weeks' gestation in whom the refractoriness to A-II was reduced by the administration of indomethacin, the intravenous infusion of 5alpha-DPH was associated with restoration of refractoriness to the pressor effects of A-II. These observations are consistent with the view that a progesterone metabolite(s) may be important in the maintenance of normal blood pressure during human pregnancy.

20-alpha-Dihydroprogesterone↗
PubMed1979

Suppression of mixed lymphocyte reaction by progesterone and estradiol-17beta.

The effects of estrone, estradiol-17beta, estriol, testosterone, progesterone, and 20alpha-dihydroprogesterone on incorporation of 3H-thymidine into cultured lymphocytes from normal men and nonpregnant women in response to allogeneic stimulation was investigated with two-way MLR. A dose-dependent reduction in the mean percent incorporation was observed in the range of progesterone concentration between 2 x 10(3) and 10(4) ng/ml with statistically significant differences from the control cultures. Estradiol-17 beta at 10(4) ng/ml produced a slight but significant inhibition of incorporation. No significant change in incorporation occurred with the other steroids tested. Since the suppressive property of progesterone in phytohemagglutinin-induced lymphocyte culture reported in our previous communication was reproduced by the present investigation in MLR, the possible role of progesterone in immunoregulation during pregnancy is emphasized as has been postulated previously.

20-alpha-Dihydroprogesterone↗
PubMed1975

17alpha-Ethyl-20alpha-and -20beta-dihydroprogesterones and other 17alpha-ethyl-substituted pregnanes as potential contragestational agents.

The 17alpha-ethyl-substituted analogs of the two epimeric 20-dihydroprogesterones, allopregnadedione and pregn-5-ene-3,20-dione, were synthesized and evaluated for their possible oral contragestational (postcoital antifertility) activity in the rat. The compounds, though bound strongly to the progesterone receptor in vitro, were inactive preimplantively at 10 mg/kg and postimplantively at 40 mg/kg in vivo.

20-alpha-Dihydroprogesterone↗
PubMed1978

Periovulatory steroid concentrations in HCG-treated rabbits.

The level of pregnenolone increased within 1 h and remained high for 4 h after an intravenous injection of HCG in conscious rabbits. Peaks for progesterone, estrogens and dehydroepiandrosterone were recorded at 2 h, and that of 20alpha-dihydroprogesterone 6 h after HCG injection. At the time of ovulation the serum concentrations of all steroids had returned to their basal levels. It seems that HCG maintained a high production of pregnenolone and promoted the synthesis of different steroids.

20-alpha-Dihydroprogesterone↗
PubMed1977

Initiation of human parturition. VI. Identification and quantification of progesterone metabolites produced by the components of human fetal membranes.

The fetal membranes play a central role in the initiation of human parturition, a role that may be subserved in part by quantitative changes in progesterone metabolism. In order to identify and to quantify the metabolites of progesterone produced by the components of the human fetal membranes, amnion and chorion laeve tissues and homogenates were incubated with [3H]progesterone in the presence of added NADPH. The radioactive metabolites, 20alpha-hydroxy-4-pregnen-3-one, 5alpha-pregnane-3,20-dione and 3beta-hydroxy-5alpha-pregnan-20-one, were isolated and identified by derivative formation, a combination of chromatographic techniques, and by crystallization to constant specific activity after addition of authentic standards. A simplified technique of metabolite quantification was developed that involves one thin layer chromatographic procedure and liquid scintillation assay of radioactivity. The accuracy of this method was established by comparison with data obtained using classical techniques. This study demonstrates the presence of human fetal membranes 5alpha-reductase, 20alpha-hydroxysteroid oxidoreductase, and 3beta-hydroxy-steroid oxidoreductase, and a qualitative difference between amnion and chorion laeve.

20-alpha-Dihydroprogesterone↗
PubMed1976

Hormonal changes during the menstrual cycle of the baboon (Papio hamadryas).

Eleven unconjugated steroids were measured daily during a complete cycle in the peripheral plasma of 6 normally menstruating baboons (Papio hamadryas) by means of a radioimmunoassay procedure and the levels were compared with those found previously in 17 normally menstruating women. The patterns of progesterone and 20alpha-dihydroprogesterone were very similar to those found in women throughout the entire menstrual cycle. However, the ratio of these steroids differed markedly from that found in women. A great similarity of the follicular phase and the peri-ovulatory period profiles was observed in both species for 17-hydroxy-progesterone, pregnenolone, androstenedione, oestradiol and oestrone. The pattern of oestradiol:oestrone ratios was similar in both species. However, an elevation of the above five steroids, typical for the human luteal phase, was not found in baboons. The increase of testosterone values, seen in women at mid-cycle, was not detected in baboons. The plasma concentrations were lower in baboons than in humans for all the above steroids.

17-alpha-Hydroxypregnenolone↗
PubMed1976

Plasma levels of unconjugated steroids in male baboons (Papio hamadryas) and rhesus monkeys (Macaca mulatta).

In an attempt to find suitable animal models to aid in the study of the reproductive processes of the human male, plasma levels of unconjugated pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, 20alpha-dihydroprogesterone, 17-hydroxyprogesterone, androstenedione, testosterone, dihydrotestosterone, oestrone and oestradiol were measured in 18 male baboons and 10 male rhesus monkeys and the steroid levels were compared with those previously established in normospermic, middle-aged men. Significant species differences were found with regard to the three delta5-steroids studied; whereas the approximate relationship of pregnenolone to 17-hydroxypregnenolone and dehydroepiandrosterone was 1:2:4 in men, the corresponding relationship was 1:5:30 in rhesus monkeys and 1:10:10 in baboons. Similar levels of 20alpha-dihydroprogesterone were found in the three species. On the other hand, the 17-hydroxyprogesterone levels in baboons were much lower and the levels of androstenedione lower than those found in men and in rhesus monkeys. No species difference was found with regard to circulating testosterone levels. However, both rhesus monkeys and baboons exhibited much higher levels of dihydrostestosterone than did men. Oestrone levels were higher in baboons than in men and oestradiol levels were higher in rhesus monkeys than in men and in baboons. The significant differences in circulating steroid levels suggest that further studies (including i.a. steroid analyses in testicular tissue, seminal plasma and spermatic artery and vein following both stimulation and suppression of testicular endocrine function) are required before preference can be given to any of the two species studied as a suitable animal model for the study of new fertility regulating agents.

17-alpha-Hydroxypregnenolone↗
PubMed1979

Effect of stress on the profile of plasma steroids in baboons (Papio hamadryas).

Adult baboons (5 males and 5 females) were exposed to immobilization stress by being strapped to a table in a horizontal position for 2 h. In females the experiment was performed during both the follicular and luteal phase. Peripheral blood was withdrawn at frequent intervals, the first sample just before immobilization, and the last one 3 days later. A number of steroids were measured in blood plasma samples by radioimmunoassay (17-hydroxypregnenolone, 17-hydroxyprogesterone, pregnenolone, testosterone, dihydrotestosterone, progesterone, 20alpha-dihydroprogesterone, oestone, oestradiol) or competitive protein binding (cortisol) techniques. The cortisol levels exhibited a marked increase in both sexes. This increase was observed already during the immobilization and lasted for approximately 24 h. A similar, even more pronounced increase was seen in 17-hydroxypregnenolone, 17-hydroxyprogesterone and pregnenolone levels. A marked, long-lasting (72 h) decrease of testosterone and dihydrotestosterone levels was a consistent finding in male baboons. This was not observed in the females which, on the other hand, exhibited a marked decrease (duration 48 h) of progesterone and 20alpha-dihydroprogesterone levels during the luteal phase, and a significant decrease (duration greater than 24 h) of oestradiol and oestrone concentrations during the follicular phase. It is concluded that stress has a marked inhibitory action on gonadal function both in male and female baboons. In females and inhibition of steroidogenetic function is exerted both on the ovarian follicles and on the corpus luteum.

17-alpha-Hydroxypregnenolone↗
PubMed1978

[Specific binding of 3H-progesterone to a plasma protein in the guinea pig fetus].

The presence of a protein that binds specifically and with high affinity to progesterone is found in the plasma of fetal guinea Pig. Progesterone and 5 alpha-dihydroxyprogesterone strongly compete for the 3H-progesterone-protein complex. 5 beta-dihydroxy progesterone, 20 beta-dihydroxyprogesterone, testosterone and synthetic progestagen, R-5020 (17,21-dimethyl-19-norpregna-4, 9-diene-3,20 dione), also compete but less intensely. 17-hydroxyprogesterone, aldosterone, cortisol, oestradiol and oestrone have no effect. The 3H-progesterone-protein, complex has an affinity of Kd = 8.8 +/- 3.5 x 10(-10) M and in sucrose density gradient the sedimentation coefficient is 4.6 S.

20-alpha-Dihydroprogesterone↗