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

Progesterone induced a transient increase in the incorporation of [3H]methyl groups into phospholipids of Xenopus oocytes followed by a rise in 45Ca2+ uptake. Phospholipid methylation reached a maximum as early as 15 s after progesterone treatment and returned to basal level within 2 min. Steroids inactive in promoting oocyte maturation were less effective in affecting phospholipid methylation. Methyltransferase inhibitors, 3-deaza-SIBA, SIBA, and Sinefungin, inhibited progesterone-activated stimulation of phospholipid methylation, calcium uptake and meiotic maturation. Phospholipid methylation is the earliest detectable biochemical event occurring in oocytes after exposure to progesterone followed by calcium influx and leading to germinal vesicle dissolution.
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PMID:Early stimulation of phospholipid methylation in Xenopus oocytes by progesterone. 387 22

Patterns of LH and FSH secretion were studied in menopausal and ovariectomized subjects by frequent sampling and the influence of ovarian steroids upon these patterns was observed. Subjects were 5 women who had been subjected to bilateral oophorectomy. At 8:00 AM of Study Day 1 (control day), after fasting since midnight, 5 ml of venous blood was drawn and samples were taken at 20 minute intervals thereafter for a period of 8 hours. Patency of the needle was maintained by a slow infusion of normal saline. Blood serum was stored at - 20 degrees C. The next day blood samples were similarly collected for 2 hours. Then, in 2 patients, at 10:00 AM estradiol benzoate 1 mg was administered in a single dose, after which blood samples were collected at 20 minute intervals for an additional 6 hours. On Day 3 the same procedure was followed, except that at 10:00 AM progesterone 100 mg was given in a single intravenous dose. In 3 other patients the order of steroid administration was reversed so that progesterone was given on Study day 2 and estradiol on Day 3. Serum LH and FSH concentrations were determined by double antibody radioimmunoassays. Serum LH and FSH concentrations were increased in all patients. During control periods serum LH levels fluctuated periodically in all subjects. Serum FSH concentration varied episodically in 2 patients. No synchronous pattern was noted either before or after the administration of the drugs. After estradiol was administered on Day 2 to 2 patients, serum LH concentrations declined 39-55% from pretreatment levels and serum FSH levels decreased 15-20%. In these patients episodic increases in both LH and FSH values were observed even after estradiol injection. When progesterone was given on Day 2 and estradiol on Day 3, serum LH concentrations declined promptly. Fluctuation of LH levels were apparent in 2 of the 3 patients. FSH levels declined in only 1. Progesterone alone had no effect on FSH levels. Steroids seem to modify release of gonadotrophin rather than exert sole control over gonadotrophin release.
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PMID:Episodic secretion of LH and FSH after ovariectomy. Secretory patterns in response to estrogen and progesterone. 468 7

A number of diverse biological compounds involved in the regulation of the hypothalamo-hypophyseal-ovarian axis have been examined for effects on the conversion of 3H-progesterone to 3H-5 alpha-dihydro-progesterone and 3H-3 alpha-hydroxy-5 alpha-pregnan-20-one by female rat hypothalamus and/or anterior pituitary. Broken cell preparations were incubated with 3H-progesterone and NADPH, and product 5 alpha-reduced progestins were quantitated by reverse isotopic dilution analysis. Progesterone 5 alpha-reductase activity was reduced up to 50% in the presence of 10(-2) to 10(-3) M serotonin in both preparations. At 10(-3) M, various indoles including n-acetylserotonin, melatonin, 5-methoxytryptamine, 5-methoxytryptophol, and 5-hydroxyindole acetic acid decreased by 10 to 30% 5 alpha-reduced product formation. At 10(-2) M, carbamylcholine and norepinephrine were without effect, while 10(-2) M dopamine reduced by 20% the 5 alpha-reduction of progesterone only in pituitary homogenates. The LHRH protease inhibitor bacitracin (2 X 10(-3) M) decreased by 10 to 40% progesterone 5 alpha-reductase activity in both tissues. By itself, LHRH did not affect the 5 alpha-reduction of progesterone nor did it potentiate the bacitracin effect. In the presence of 1 mM ATP, 100 micronM cAMP and 100 micronM cGMP increased 5 alpha-reduced product formation in the hypothalamus by 19 and 14%. The gonadotropins LH and FSH and the prostaglandins E1, E2, F1 alpha, and F2 alpha were without effect. Thus, these results and others indicate that a number of cellular components and other factors can affect the in vitro 5 alpha-reduction of progesterone in broken cell preparations.
Steroids 1980 Sep
PMID:The effects of neurotransmitters and other cellular modulators and factors on hypothalamic and anterior pituitary delta 4-steroid (progesterone) 5 alpha-reductase activity. 610 99

Isolated hamster granulosa cells and theca from preovulatory follicles were incubated in vitro for 2 and 6 h in the absence/or presence of LH and steroid substrates. The purpose of the experiments was to determine, in theca, the relative activities of the delta 5 and delta 4 pathways under controlled conditions, and to compare the ability of granulosa cells and theca to form progesterone from exogenous pregnenolone. The results of the experiments show that the delta 5 pathway in theca predominates before and up to 2 h after LH stimulation. The delayed effect of LH after 2 h is a switch from delta 5 to delta 4 as the major metabolic pathway. Progesterone formation from exogenous pregnenolone is 7 to 10 times greater in unstimulated granulosa cells than in theca. Acute effects of LH lead to increased conversion of exogenous pregnenolone to progesterone in granulosa cells but not theca. LH does, however, acutely stimulate the thecal conversion of DHEA to androstenedione. The longer term effect of LH in both cell types is to increase pregnenolone conversion to progesterone.
Steroids 1983 Dec
PMID:Significance of the delta 5 and delta 4 steroidogenic pathways in the hamster preovulatory follicle. 624 59

The suggestion has been made that prenatal exposure to synthetic progestogens contributes to an increased incidence of hypospadias. One potential mechanism for such an effect might be inhibition of 5 alpha-reductase, a key enzyme in normal male sexual differentiation. We have examined the effect of progesterone and of five synthetic progestogens upon 5 alpha-reductase activity in fibroblast monolayers from 12 genital skin cell lines obtained from normal newborn infants, boys with phimosis and hypospadias and a normal adult male. Basal enzyme activities ranged from 0.8-12.1 pmoles 5 alpha-reduced product/micrograms DNA/hour. Progesterone and norethindrone inhibited 5 alpha-reductase activity in a dose dependent manner to a maximum of 95% and 50% of basal levels respectively at 10(-5) M. Similar concentrations (10(-5) M) of norethynodrel, ethisterone, dl-norgestrel and d-norgestrel had little or no effect. Studies of cell viability showed that the effects of progesterone and norethindrone were specific for 5 alpha-reductase and not non-specific toxic effects.
Steroids 1984 Jan
PMID:The effect of five synthetic progestational compounds on 5 alpha-reductase activity in genital skin fibroblast monolayers. 652 31

Progesterone, estrone, estradiol-17 beta and corticosterone were quantified simultaneously for the first time in female American kestrel (Falco sparverius) plasma. A mean level for each hormone was determined for the laying and non-laying periods of the summer (April-September), and for February. Means were comparable to those of other wild avian species and were significantly higher for the laying period than for the other 2 periods. The mean corticosterone level for February was higher than that for the non-laying summer period. Plasma from laying kestrels, unlike that from other avian species, required lipid removal before column chromatography. Of 2 lipid removal techniques compared, i.e. the cold methanol and hexane:methanol techniques, the latter proved superior.
Steroids 1984 Apr
PMID:Simultaneous quantification of progesterone, estrone, estradiol-17 beta and corticosterone in female American kestrel plasma. 652 50

Testosterone biosynthesis by Leydig cells can be modulated by estradiol. This modulation appears to occur at the 17-hydroxylase and 17,20-desmolase stage. In this study we have examined the effects of estradiol and progesterone on the activities of the 17-hydroxylase (17-OH) and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in rat ovarian tissue, to examine the hypothesis that estradiol may regulate these enzymes in the ovary as well as in the testis. Estradiol capsule implants produced a decrease in 17-OH activity (0.5 +/- 0.05 vs. 2.1 +/- 0.1 nmol/mg protein/min, mean +/- SEM, p less than 0.001), and an increase in 3 beta-HSD activity (15.5 +/- 0.9 vs 9.7 +/- 0.7 nmol/mg protein/min p less than 0.001). Progesterone injections produced a decrease in both 17-OH (0.9 +/- 0.1 vs. 2.3 +/- 0.2 p less than 0.005) and 3 beta-HSD (2.5 +/- .4 vs. 8.6 +/- 0.5; p less than 0.005) activities. We conclude that estradiol decreases 17-OH activity in the ovary as it does in the testis. This, coupled with an increase in 3 beta-HSD may explain the pre-ovulatory increase in progesterone seen in many species. Progesterone seems to decrease the steroidogenic activity of the ovarian tissue, perhaps offering an explanation for the gonadotropin resistance seen in corpus luteus bearing ovaries.
Steroids 1983 Jan
PMID:The effects of estradiol and progesterone on rat ovarian 17-hydroxylase and 3 beta-hydroxysteroid dehydrogenase activities. 660 68

The effect of some sex hormones (estradiol-17 alpha), estradiol-17 beta, estrone, progesterone and testosterone) on the mechanical activity of rabbit left ventricle was studied in concentrations within the physiological range. Investigations were carried out during the first ten minutes after the introduction of the steroid. Only progesterone and estradiol-17 beta affect the isovolumetric pressure curve; the other steroids do not exhibit any effect. The effects of estradiol-17 beta and progesterone counterbalance each other. Estradiol-17 beta enhances the rate of pressure development and decreases the time to reach peak pressure. Progesterone decreases both the rate of pressure development and the time to reach peak pressure.
Steroids 1983 Jan
PMID:The effect of some sex hormones on the isovolumetric pressure curve of the rabbit's left ventricle. 665 64

Effects of steroids on the accumulation of glycoprotein gonadotropin (GTH) in pituitaries of juvenile trout were investigated by means of scanning cytophotometry applied to immunocytochemical preparations, and with the use of a radioimmunoassay. Effects on other aspects of GTH-cell activity were analyzed by measuring the size of the gonadotrops and their nuclei. Progesterone added to aquarium water and methyltestosterone incorporated into the food showed a pronounced stimulatory effect on the accumulation of GTH. To a lesser extent, treatment with cortisol, cortisone, and desoxycorticosterone acetate administered to aquarium water, and 11 beta-hydroxy-androstenedione added to the food resulted in an increase of the hypophysial content of GTH. Steroids stimulating the accumulation of GTH in the pituitary also exhibited a positive effect on GTH-cell activity as indicated by an increase in the size of gonadotropic cells. Progesterone incorporated into the food did not influence the GTH-content and the GTH-cell activity. It is suggested that the route of administration of an exogenous steroid is essential for its effect on GTH cells in trout. Comparison of GTH values reveals an excellent correlation between the data from the radioimmunoassay and those from the corresponding densitometric measurements. No correlation was observed between values of morphometrically determined GTH-cell activity and the densitometric values reflecting hypophysial GTH content.
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PMID:Accumulation of glycoprotein gonadotropin in the pituitary of juvenile rainbow trout in response to androgens and C21-steroids, including 11-steroids. 671 90

We have investigated the action of high doses of androgens in Gobius niger L., a marine teleostean fish, by characterizing specific steroid receptors in liver and by assaying the plasma vitellogenin concentration under different hormonal treatments. Estrogen and androgen receptors were characterized in the liver nuclear extracts according to their binding specificity. The maximum binding capacity was 25 fmoles/mg protein for the estrogen and androgen receptors. In vivo, high doses of DHT()increased the concentration of plasmatic vitellogenin as assayed by immunodiffusion while low doses were inefficient. In spite of a similar number of estrogen and androgen nuclear receptor sites (25 fmoles/mg protein), DHT was at least 70 fold less active than E2 on yolk protein and vitellogenin induction both in male and female Gobius niger. In addition, the antiestrogen tamoxifen, which was inactive by itself, inhibited the E2 and the DHT induced accumulation of vitellogenin. Progesterone (2 mg/fish) was also totally inactive in inducing vitellogenin. We conclude that the induction of vitellogenin by DHT is mediated by the estrogen receptor rather than by the androgen receptor. In addition to the estradiol induced protein in rat uterus and to other estrogenic responses obtained by androgens in mammary cancer, fish vitellogenin is another estrogen regulated protein which can be induced by high doses of androgens.
Steroids 1980 Mar
PMID:Effect of androgen mediated by the estrogen receptor of fish liver: vitellogenin accumulation. 676 82


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