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

The in vivo and in vitro metabolism of 3H-testosterone by rat epididymis and the changes in epididymal weight have been studied after castration and treatment with anti-androgens. The utilization of 3H-testosterone was greatly reduced after castration as was the formation of 5alpha-reduced 17 beta-hydroxy metabolites. The formation of the 17 -keto metabolites was unaffected. Castration had no effect on the ratio between water and ether soluble radioactivity. Administration of testosterone propionate, necessary for giving normal stimulated prostate weight (150 mug/day), restored the metabolism of testosterone to approximately normal values. Estradiol benzoate and progesterone inhibited metabolism of testosterone in vitro and greatly reduced the formation of DHT (17 beta-hydroxy-5alpha-androstan-3-one) and 3 alpha-diol(5 alpha-androstane-3 alpha-17 beta-diol) by experiments both in vivo and in vitro. No effect of cyproterone acetate could be demonstrated on either the in vitro or in vivo metabolism of testosterone. Castration for 14 days reduced the epididymal weight to about 30% of that found in intact animals. Administration of testosterone propionate restored the epididymal weight to about 80% of normal. Estradiol benzoate and cyproterone acetate given to intact rats led to a decrease in the epididymal weight. Progesterone had no such effect. In 14 days castrated rats receiving testosterone propionate all three anti-androgens reduced the weight of the epididymis. In conclusion, our results show that the metabolic conversion of testosterone in epididymis to DHT and 3 alpha-diol is dramatically dependent on the hormonal status of the animal; castration or treatment with anti-androgens causes a reduced formation of the "active" androgens whilst testosterone replacement treatment restores the metabolism of testosterone to normal.
Steroids 1976 Jan
PMID:Androgen metabolism by rat epididymis. 3. Effect of castration and anti-androgens. 126 92

Steroids (testosterone, oestrogen, progesterone, corticosterone, dexamethasone and deoxycorticosterone) were administered intramuscularly (0.1 mg.100 g bw-1) on seven consecutive days to juvenile male soft-shelled turtles. Serotonin, norepinephrine and epinephrine contents of the pineal-paraphyseal complex were measured spectrofluorometrically 24 h after the last injection. Testosterone and oestrogen decreased serotonin, norepinephrine and epinephrine levels. Progesterone treatment resulted in an increase of serotonin level and a fall in norepinephrine and epinephrine levels. Corticosterone treatment caused an increase of serotonin level and a decrease of norepinephrine and epinephrine levels. Dexamethasone failed to alter serotonin content, increased norepinephrine and decreased epinephrine levels. Deoxycorticosterone decreased serotonin and elevated epinephrine content.
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PMID:Effect of steroid hormones on serotonin, norepinephrine and epinephrine contents in the pineal-paraphyseal complex of the soft-shelled turtle (Lissemys punctata punctata). 143 Apr 21

All the classes of hormonal steroids physiologically produced in the body (androgens, estrogens, progestagens, and corticosteroids) are able to exert important effects on the brain, but the mechanisms of their actions are not always well understood. Steroids may interact with intracellular receptors to activate the genome, but some of their effects are probably extragenomic and involve interactions with cellular membranes. Moreover, not all the steroids act always in their native molecular form; a large group of them must actually be transformed into "active" metabolites. This may occur at the level of their respective target structures. For example, androgens are metabolized in the brain into estrogens and into 5 alpha-reduced androgens, like 5 alpha-androstan-17 beta-ol-3-one (dihydrotestosterone; DHT) and 5 alpha-androstan-3 alpha, 17 beta-diol (3 alpha-diol). Progesterone, and possibly corticosteroids, may also be transformed into their corresponding 5 alpha-reduced metabolites. Also the cellular target (neurons and/or glial cells) of the hormonal steroids in the brain is not always clear. This review analyzes in detail one of the two major enzymatic systems that transform steroids in the brain, namely the 5 alpha-reductase-3 alpha-(3 beta)-hydroxysteroid dehydrogenase pathway. An active 5 alpha-reductase-3 alpha-hydroxysteroid dehydrogenase system is widely distributed in practically all CNS structures in all phases of development. In the brain, this enzymatic system is not regulated by castration or sex steroid administration; furthermore, neural inputs seem to be ineffective at the hypothalamic level. A recent interesting finding is the presence of high concentrations of the 5 alpha-reductase in the white matter. This probably is due to the fact that the white matter is particularly rich in myelin membranes, with which the enzymatic activity appears to be associated. An active 5 alpha-reductase activity has also been shown to be present in peripheral myelinated nerves. The localization in myelin membranes may suggest a possible involvement of 5 alpha-reduced metabolites of the different steroids in the process of myelination. The presence of the 5 alpha-reductase was analyzed in neurons, astrocytes, and oligodendrocytes isolated from the brains of male rats, as well as in neurons and glial cells grown in culture. Neurons appear to be more active than glial cells in converting testosterone into DHT. Only neurons possess aromatase activity.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The 5 alpha-reductase in the brain: molecular aspects and relation to brain function. 146 1

Steroid concentrations in plasma and follicular tissues (theca plus granulosa layers) were determined by radioimmunoassay in the aplacental viviparous ray, Torpedo marmorata, during various stages of the reproductive cycle. Steroids in the uterine fluid of pregnant animals and in preovulatory atretic follicles were also measured. In the follicular tissue of cyclic animals, levels of progesterone were always lower than those of estradiol-17 beta and androgens (testosterone plus 5 alpha-dihydrotestosterone). Estradiol-17 beta and androgen levels increased as the animals approached the ultimate maturational stage before ovulation. Androgens were not detectable in plasma, while estradiol-17 beta increased dramatically before ovulation. In pregnant animals, only small ovarian follicles (less than 5 mm in diameter) were observed, and these had hormone concentrations that were similar to those of the small follicles of cyclic animals. Progesterone was the only steroid detected in the uterine fluid of pregnant animals. In completely sclerotic atretic follicles of pregnant animals, steroids were not detected. Progesterone was the main hormone in atretic follicles undergoing yolk resorption. This suggests that the latter may contribute to the elevated plasma progesterone concentrations of pregnant animals.
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PMID:Plasma and follicular tissue steroid levels in the elasmobranch fish, Torpedo marmorata. 160 Dec 64

The study reported here examined the effects of a phytoestrogen diet on progestin receptor induction, vaginal opening, and the onset and maintenance of vaginal cycles in developing female rats. A natural dietary concentration (0.01%) of the isoflavonoid coumestrol was incorporated into the AIN semipurified diet and fed from 21 to 24 days (acute treatment) or from 22 to 60 days (chronic treatment). Progestin receptor induction was observed in the uterus, pituitary, and hypothalamus-preoptic area following acute treatment. Responses were more marked in the uterus and pituitary than in the hypothalamus-preoptic area. Vaginal opening was accelerated by 4 days during chronic coumestrol treatment and occurred at a lighter body weight. Vaginal cycles began on vaginal opening and did not differ in regularity from those of control animals. However, irregular cycles were observed in coumestrol-treated animals at 116 to 131 days, suggesting that chronic coumestrol treatment may have induced some permanent changes in reproductive function. These findings demonstrate that plant estrogens, at natural dietary levels, produce significant, agonistic actions in several estrogen-dependent tissues and processes.
Steroids 1992 Feb
PMID:Effects of a phytoestrogen diet on estrogen-dependent reproductive processes in immature female rats. 162 Dec 56

A 59-year-old previously oophorectomized woman underwent surgery for a recurrent malignant granulosa cell tumor. Specimens and dispersed cells from the tumor tissue were incubated for 2 hr and cultured for 48 hr, respectively, with and without gonadotropins. Steroids and cyclic AMP (cAMP) concentrations were measured in the incubation and culture media. Incubated specimens from the tumor tissue released measurable amounts of cAMP, progesterone, and estradiol into the medium. Human follicle-stimulating hormone (FSH) 1 microgram/ml significantly stimulated the formation of cAMP and both steroids. Human luteinizing hormone (LH) 1 microgram/ml stimulated cAMP and progesterone but not estradiol release. Human chorionic gonadotropin (hCG) 10 micrograms/ml stimulated cAMP and progesterone formation in tumor tissue but was totally devoid of effect on estradiol release. In the tissue culture experiments progesterone and estradiol were formed in considerable amounts, with a higher capacity for progesterone than for estradiol. Progesterone formation was stimulated by FSH and hCG, while estradiol release was stimulated only by hCG. The addition of testosterone significantly enhanced estradiol formation in both incubation and culture experiments. It is concluded that the steroidogenesis of this granulosa cell tumor is sensitive to gonadotropins.
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PMID:Human granulosa cell tumor: stimulation of steroidogenesis by gonadotropins in vitro. 184 99

The stimulatory and inhibitory effects of progesterone on luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion were found to be dependent on the length of estrogen exposure in ovariectomized estrogen-primed rats. Progesterone suppressed LH and FSH secretion when administered 16 hours after a single injection of estradiol to ovariectomized rats. If the estradiol treatment was extended over 40 hours by two injections of estradiol 24 hours apart, progesterone administration led to a highly significant elevation of both serum LH and FSH levels 6 hours later. In addition to the direct stimulatory effect on LH and FSH release, progesterone, when injected 1 hour before, was able to antagonize the suppressive effect of a third injection of estradiol on LH and FSH release. In the immature ovariectomized estrogen-primed rat, 10 IU of ACTH brought about a release of progesterone and corticosterone 15 minutes later and LH and FSH 6 hours later. Progesterone, but not corticosterone, appeared to be responsible for the effect of ACTH on gonadotropin release. The synthetic corticosteroid triamcinolone acetonide brought about LH and FSH release in the afternoon, while cortisol, similar to corticosterone, was unable to do so. Nevertheless, triamcinolone acetonide and cortisol brought about increased secretion of FSH the following morning.
Steroids 1991 Feb
PMID:Validation of the mechanisms proposed for the stimulatory and inhibitory effects of progesterone on gonadotropin secretion in the estrogen-primed rat: a possible role for adrenal steroids. 185 May 62

Steroids modulate the secretory activity of the uterus, but little is known of their effect on ectopic endometrium protein synthesis and secretion. We utilized two-dimensional electrophoresis to visualize proteins produced by the uteri and endometriotic implants of both steroid-treated and reproductively cyclic rats with and without surgically induced endometriosis. Of the greater than 300 proteins visualized, only the uterine cultures from progesterone (P)-stimulated, estrogen-suppressed rats contained a distinctive glycoprotein (P-induced uterine protein-1; molecular weight [Mr] 70,000; isoelectric point [pI] 5.7). This protein was not detected in any of the endometriotic implant cultures. Progesterone-induced uterine protein-1 could play a role in luteal or endometrial physiology and may be valuable in assessing endometrial function. The aberrant secretory behavior of the ectopic endometrium suggests a possible involvement in the reproductive dysfunction associated with endometriosis.
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PMID:Detection of a progesterone-induced secretory protein synthesized by the uteri but not the endometriotic implants of rats with induced endometriosis. 199 38

Progesterone and estradiol interact to regulate secretion of prostaglandin (PG) F2 alpha from the ovine endometrium in response to oxytocin. Two experiments were conducted to determine if these effects were due to changes in activity of phospholipase C or in the second messenger responsive pathways that regulate production of PGF2 alpha. In both experiments, ovariectomized ewes were assigned to one of four treatment groups (control, estradiol, progesterone, progesterone and estradiol). Steroids were administered, in vivo, to mimic the changes that occur during the estrous cycle. On Day 16 of steroid treatment, endometrial tissue was collected and incubated, in vitro, to measure activity of phospholipase C and release of PGF2 alpha. Treatment with progesterone, in vivo, enhanced basal and oxytocin-induced activity of phospholipase C and release of PGF2 alpha, in vitro. Estradiol suppressed oxytocin-induced activity of phospholipase C, both in the presence and absence of progesterone. In contrast to its effects on phospholipase C, estradiol inhibited basal and oxytocin-induced release of PGF2 alpha when administered alone, but not when administered with progesterone. Steroids had similar effects on the release of PGF2 alpha induced by phorbol 12-myristate 13-acetate and A23187. It was concluded that progesterone and estradiol regulate endometrial release of PGF2 alpha by affecting both the activity of phospholipase C and its associated second messenger responsive pathways that may regulate production of PGF2 alpha.
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PMID:Activity of phospholipase C and release of prostaglandin F2 alpha by endometrial tissue from ovariectomized ewes receiving progesterone and estradiol. 201 59

The urinary excretion pattern of 2-hydroxyestrone, estradiol, estrone, and progesterone was examined in rats during early, mid, and late pregnancy. Progesterone increased from early to mid pregnancy and declined significantly 2 to 3 days prior to parturition, corresponding to changes observed in blood levels by others. 2-Hydroxyestrone, the major estrogen in rat urine, increased significantly 4 days prior to delivery and remained elevated until it further increased sharply the day of parturition. Urinary estradiol and estrone levels showed little change until the day of parturition, when they increased significantly. Multiple correlation analysis of the data implied that 2-hydroxyestrone and estradiol were negatively correlated at the time of implantation. The results suggest that catechol estrogens, through their effect on prostaglandin synthesis, may participate in the process of implantation as well as in the mechanism involved in the onset of labor.
Steroids 1991 Mar
PMID:Temporal relationships among the excretory patterns of 2-hydroxyestrone, estrone, estradiol, and progesterone during pregnancy in the rat. 204 32


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