Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00627 (MAP)
 15,705 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of estradiol benzoate in the female rat, testosterone propionate in the male rat, and castration in both sexes on specific prolactin binding sites in the particulate membranes of the kidneys and adrenals were studied. Castration resulted in a significant increase in PRL binding activity in the kidneys of both males and females, and in a significant increase in PRL binding activity in the adrenals of the females. The increase in PRL binding with castration and the decrease seen with testosterone treatment were similar in both immature and mature rats. Progesterone administration to castrate females failed to alter PRL binding in both tissues. The present results suggest that estrogen and testosterone participate in the PRL osmoregulatory system in rat.
Steroids 1976 Feb
PMID:Effects of estrogen and testosterone on specific prolactin binding in the kidneys and adrenal of rats. 17 68

Previous studies on cytoplasmic glucocorticoid receptors and enzyme induction led to the classification of steroids as inducers (optimal or sub-optimal), antagonists, or inactive steroids, with respect to their activity as glucocorticoids. The receptor was postulated to exist in allosteric equilibrium between two conformational states, one "active" and the other "inactive". Steroids behaved as inducers (optimal or sub-optimal), antagonists, or inactive steroids depending on their relative affinity for the active and inactive conformational state of the receptor. Another possible model would invoke multiple binding sites on a single receptor with interactions between the binding sites depending upon the particular steroid bound. To test this latter possibility, an experimental technique was developed to measure the rate of dissociation of tritiated dexamethasone ([3H]DM) or tritiated aldosterone ([3H]A) from the glucocorticoid receptor of rat liver or kidney cytosol. The dissociation of the [3H]DM-receptor at 25 C was not due to irreversible denaturation, and minimal recombination of the receptor with [3H]DM occurred. Progesterone and a number of other steroids consistently and significantly increased the dissociation rate of [3H]DM-receptor complexes in both liver and kidney cytosol. An identical effect was seen with hepatic glucocorticoid receptors labelled with [3H]A, like dexamethasone an optimal inducer. All steroids which enhanced glucocorticoid-receptor dissociation were either antagonists or sub-optimal inducers. Thus, it is postulated that glucocorticoid receptors have at least two classes of binding sites, and that occupation of the second site increases the dissociation rate of agonists from glucocorticoid receptors.
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PMID:Glucocorticoid receptors: evidence for a second, non-glucocorticoid binding site. 18 Dec 39

The specific binding of [3H] prostaglandin (PG) F2alpha to bovine corpus luteum cell membranes was inhibited by progesterone. Progesterone inhibition of binding was dependent on membrane protein and independent of [3H] PGF2alpha concentrations in the medium. The lower inhibition of binding at high protein concentrations can be overcome by increasing the amounts of progesterone added. Progesterone inhibition of binding appears to be due to a decrease in the receptor number rather than a decrease in the receptor affinities. The kinetic properties (association and dissociation rates) of the remaining receptors were unchanged. The inhibition of [3H] PGF2alpha binding was observed by preincubating the membranes with progesterone or by adding at the beginning but not during incubation. The concentrations of progesterone that inhibited binding by about 50% do occur in bovine corpora lutea of estrous cycle and pregnancy.
Steroids 1976 Jun
PMID:Inhibition of (3H) prostaglandin F2alpha binding to its receptors by progesterone. 18 73

Daily administration of LH-RH (100 micrograms sc at 0900 and 1500 h) to rats over day 7-12 (D7-12) of pregnancy induced reovulation by D9 and a sustained decrease in uterine:fetal weight and vaginal bleeding by 0600 h on D10 of pregnancy. Serum hormone levels determined at 0600, 1200, and 2000 h over D7-12 of pregnancy revealed that luteinizing hormone (LH) was significantly elevated after each administration of LH-RH, while prolactin (PRL) was not significantly altered in any systematic fashion. An acute decline in serum progesterone at 2000 h on D7-9 following LH-RH administration was not sustained until after 0600 h on D10 when serum 20 alpha-dihydroprogesterone (20 alpha-hydroxy-4-pregnen-3-one, 20 alpha-DHP) in LH-RH treated animals rose significantly above control (2000 h, D10) and remained elevated throughout D11-12. Progesterone and 20 alpha-DHP values were reflected morphologically after D10 as the corpora lutea of LH-RH treated rats underwent luteolysis. A peak in serum estradiol levels in control animals was observed at 0600 h on D9. Serum estradiol-17 beta levels in LH-RH treated animals were similar to control except at 2000 h on D8 and D12 when LH-RH induced a significant increase. These observations suggest that subsequent to implantation in the rat, the temporal sequence of a decrease in progesterone secretion, luteolysis and pregnancy failure in response to LH-RH does not result from an increase in estradiol secretion attendant to reovulation.
Steroids 1979 Oct
PMID:Serum hormone levels during a post-implantation LH-RH induced luteolysis in the rat. 39 Jul 77

Progesterone, 20alpha-dihydroprogesterone, estrone and estradiol-17beta concentrations were estimated by radioimmunoassay in blood plasma from uterine, uteroovarian and femoral veins of rhesus monkeys (Macaca mulatta) on days 22, 49, 128 and 160 of gestation. Steroids were consistently more concentrated in uterine and uteroovarian that in femoral venous plasma and in many cases levels in the uteroovarian vein were also higher than those in the uterine vein indicating luteal secretion of both progestins and estrogens thoughout gestation. In some animals, however, the corpus luteum appeared quiescent. As reflected in the decline in the uterine venous progesterone/estradiol-17beta concentration ratio, a shift in steroid contribution from the uterus and its contents occurred between days 22 and 49 of gestation with progesterone declining more rapidly than estradiol-17beta. Progesterone/20alpha-dihydroprogesterone was higher in both uterine and uteroovarian than in femoral venous plasma suggesting peripheral metabolism of progesterone to 20alpha-dihydroprogesterone.
Steroids 1977 Feb
PMID:Placental and luteal steroidogenesis in the pregnant rhesus monkey. 40 21

Blood samples were collected from eight mares for ten days before and two days following parturition. Progesterone, 5 alpha-dihydroprogesterone and hydroxy-5 alpha-pregnanones were extracted from serum, separated by Sephadex LH-20 column chromatography and quantitated by radioimmunoassay. Progesterone levels ranged from 8.5 to 4.1 ng/ml among mares with normal parturition and decreased to 1.2 ng/ml after parturition. One mare with a retained placenta maintained the prepartal levels of progesterone into the postpartum period. 5 alpha-dihydroprogesterone increased to a level of 133 ng/ml at 80 hrs before parturition and began decreasing and reached a level of 9.2 ng/ml in the postpartum period. Levels of hydroxy-5 alpha-pregnanones were variable with a high of 1690 ng/ml and declined to a postpartum level of 60 ng/ml. The timing of the decline varied among the mares. The possible source and significance of these progestins remain speculative.
Steroids 1979 Jan
PMID:Serum levels of progesterone, 5 alpha-dihydroprogesterone and hydroxy-5 alpha-pregnanones in the prepartum and postpartum equine. 45 61

In vitro and in vivo synthesis of progesterone, sequestration of progesterone from the surrounding medium, and its subsequent conversion to metabolites was investigated in 146 hr post coitus preimplantation rabbit blastocysts. No significant conversion of 3H-pregnenolone to 3H-progesterone was observed throughout the 8 hr incubation. Progesterone content in blastocysts and culture medium did not change during the course of an 8 hr incubation. This suggests that the failure to detect incorporation of label into progesterone was not due to the presence of a large endogenous pool of pregnenolone. Significant uptake (p less than 0.05) of 3H-progesterone from the incubation medium was observed as was significant conversion of the 3H-progesterone to unidentified metabolites. Therefore it would appear that the preimplantation rabbit blastocyst is not capable of de novo synthesis of progesterone from pregnenolone prior to implantation but sequesters progesterone from the surrounding medium and converts it to progesterone metabolites.
Steroids 1979 Jun
PMID:The source of progesterone in preimplantation rabbit blastocysts. 46 3

3 alpha-Hydroxy-17-acetoxy-6 alpha-methyl-5 beta-pregnan-20-one (IIIa) has been isolated from urine of patients receiving medroxyprogesterone acetate (MPA). It was characterized by partial synthesis from MPA by catalytic reduction with palladium-charcoal to 17-acetoxy-6 alpha-methyl-5 beta-pregnan-3,20-dione (IV) and reduction of the latter with sodium borohydride. The isolation of 6 beta, 17,21-trihydroxy-6 alpha-methyl-pregn-4-ene-3,20-dione (IIc) is reported for the first time. The 17- and 21-monoacetates of this compound have been isolated and characterized earlier by other investigators. 7 alpha-3H-Medroxyprogesterone acetate was administered to 4 subjects by intravenous and intramuscular injections and by mouth. The ring A saturated metabolite IIIa was excreted in 0.1% to 4.0% of the administered dose; the highest excretion was after the intravenous dose and lowest after oral ingestion. 6 beta, 17,21-Trihydroxy-6 alpha-methylpregn-4-ene-3,20-dione (IIc) and its 17- and 21-monoacetates were excreted in about 5% of the doses in all subjects. No increase in 6 beta-hydroxylation was observed in the patient treated with o,p'-DDD,2,2-bis(2-chlorophenyl, 4'-chlorophenyl)-l,1-dichloroethane.
Steroids 1979 Jul
PMID:Isolation and partial synthesis of a new metabolite of medroxyrogesterone acetate. 48 36

The molecular conformation of 17-hydroxy-6 alpha-methylprogesterone has been determined crystallographically and is compared with 17-hydroxy-progesterone, 17-acetoxyprogesterone and 17-acetoxy-6 alpha-methylprogesterone (MPA). The analysis demonstrates that the 6 alpha-methyl substituent is not sufficient by itself to induce inversion of the A-ring. Consequently, the inverted form observed in MPA and proposed to be responsible for high affinity binding to the progesterone receptor appears to be induced by the combined long range influence of 17 alpha-acetoxy substituent and the direct interaction of the 6 alpha-methyl group with the flexible A-ring.
Steroids 1979 Nov
PMID:Steroid structure and function V. A-ring conformation in 17-hydroxy-6 alpha-methylprogesterone. 51 15

Progesterone-4-14C was extensively metabolized during incubation with dispersed trophoblast prepared from chorionic membranes of the 21-day sheep conceptus. Of the metabolites formed, 17, 20 alpha-dihydroxypregn-4-en-3-one, 20 alpha-hydroxypregn-4-en-3-one, 20 beta-hydroxypregn-4-en-3-one, 5 alpha-pregnane-3 alpha, 17,20 alpha-triol, 5 beta-pregnane-3 alpha, 17,20 alpha-triol, 5 beta-pregnane-3 alpha,20 alpha-diol, 3 beta-hydroxy-5 alpha-pregnan-20-one, 3 alpha-hydroxy-5 beta-pregnan-20-one, 20 beta-hydroxy-5 beta-pregnan-3-one, 5 alpha-pregnane-3,20-dione and 5 beta-pregnane-3,20-dione were identified. These findings indicate that the sheep conceptus acquires extensive steroid metabolizing capability very early in pregnancy.
Steroids 1979 Dec
PMID:Metabolism of progesterone by chorionic cells of the early sheep conceptus in vitro. 53 81


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