Hormone-regulated expression and distribution of versican in mouse uterine tissues.

BACKGROUND: Remodeling of the extracellular matrix is one of the most striking features observed in the uterus during the estrous cycle and after hormone replacement. Versican (VER) is a hyaluronan-binding proteoglycan that undergoes RNA alternative splicing, generating four distinct isoforms. This study analyzed the synthesis and distribution of VER in mouse uterine tissues during the estrous cycle, in ovariectomized (OVX) animals and after 17beta-estradiol (E2) and medroxyprogesterone (MPA) treatments, either alone or in combination. METHODS: Uteri from mice in all phases of the estrous cycle, and animals subjected to ovariectomy and hormone replacement were collected for immunoperoxidase staining for versican, as well as PCR and quantitative Real Time PCR. RESULTS: In diestrus and proestrus, VER was exclusively expressed in the endometrial stroma. In estrus and metaestrus, VER was present in both endometrial stroma and myometrium. In OVX mice, VER immunoreaction was abolished in all uterine tissues. VER expression was restored by E2, MPA and E2+MPA treatments. Real Time PCR analysis showed that VER expression increases considerably in the MPA-treated group. Analysis of mRNA identified isoforms V0, V1 and V3 in the mouse uterus. CONCLUSION: These results show that the expression of versican in uterine tissues is modulated by ovarian steroid hormones, in a tissue-specific manner. VER is induced in the myometrium exclusively by E2, whereas MPA induces VER deposition only in the endometrial stroma.

[In vitro metabolic interaction between diphenytriazol and steroid hormone drugs].

AIM: To observe the metabolic interaction between diphenytriazol and steroid hormone drugs, and provide some useful information for clinical medication. METHODS: The steroid hormone drugs which may be co-administrated with diphenytriazol were selected, such as mifepriston, estradiol, medroxyprogesterone acetate, progesterone, norethisterone and so on. Diphenytriazol was incubated with each drug in rat liver microsome. The residual concentration of diphenytriazol or steroid hormone drugs in the microsomal incubates was determined by reversed-phase high-performance liquid chromatography, separately. The inhibition constants (K(i)) for each of them were calculated. RESULTS: The inhibition constant K(is) of diphenytriazol for the metabolism of mifepristone, estradiol, medroxyprogesterone acetate, progesterone and norethisterone were (201.3 +/- 1.0), (94 +/- 4), (128.7 +/- 2.2), (64 +/- 5) and (80 +/- 4) micromol x L(-1), respectively. The inhibition constants K(i) of steroid hormone drugs for the metabolism of diphenytriazol was (66.9 +/- 2.2) micromol x L(-1) for estradiol, (60.0 +/- 2.3) micromol x L(-1) for medroxyprogesterone acetate, (163 +/- 10) micromol x L(-1) for progesterone and (88 +/- 5) micromol x L(-1) for norethisterone, respectively. CONCLUSION: Diphenytriazol shows metabolism interaction with steroid hormone drugs such as estradiol, medroxyprogesterone acetate, progesterone and norethisterone.

Medroxyprogesterone acetate: a steroid with potent progestational activity but low receptor affinity in the guinea pig uterus.

The guinea pig progestin receptor appears to be unique among mammalian receptors studied to date in that it displays a low binding affinity for some biologically potent 17 alpha-substituted progestinss. [3H]Medroxyprogesterone acetate (MPA) was synthesized and used to investigate this dichotomy between binding affinity and biological activity. The comparison of cytoplasmic and nuclear receptor binding characteristics suggested that progesterone and MPA were bound to the same receptor but with different affinities. Following an intravenous injection of 3H-steroids, the plasma level of progesterone was lower than that of MPA at all time points. Correspondingly, for up to 6 hours following steroid administration, progesterone levels were lower in uterine cytoplasm and higher in nuclei than those of MPA. However, by 24 hours, MPA nuclear levels were higher than those of progesterone, in accordance with plasma levels. We conclude that the potent biological activity of MPA relative to progesterone is due in part to its slower rate of metabolism and longer nuclear retention.

The in vivo metabolism of progestins. I. The metabolic clearance rates of progesterone and medroxyprogesterone acetate in the dog.

[3H]Medroxyprogesterone acetate (MPA) was synthesized by selective catalytic tritiation of the delta1-olefinic bond of 6alpha-methyl-17alpha-hydroxy-pregn-1,4-diene-3,20 dione acetate. [14C]MPA was synthesized by acetylation of 6alpha-methyl-17alpha-hydroxy-pregn-4-ene-3,20-dione with [14C]acetic anhydride. These radioactive materials were used to determine the MPA metabolic clearance rates (MCRMPA)and volumes of distribution (VoMPA) in dogs by the single injection technique. The metabolism of progesterone was also studied in the same animals. The MCRMPA (696 +/- 51 l/day) was only one-half that of progesterone (1332 +/- 59). By contrast, the volumes of distribution for the two steroids were similar. The metabolic clearance rates and the volumes of distribution for MPA and progesterone did not change during treatment with amino-glutethimide, a drug which is known to alter steroid metabolism in man.

Nuclear progestin receptors in normal and malignant human endometrium.

PIP: The use of medroxyprogesterone acetate (MPA) was incorporated into a nuclear receptor assay for progestin receptor in human endometrium. The assay was developed because MPA is a better ligand than progesterone since it does not bind to corticosteroid-binding globulin and gives greater kinetic stability to the nuclear complex. The MPA nuclear receptor complex for malignant endometrium dissociated at a faster rate than did the complex obtained from normal endometrium, an alteration in binding kinetics which could not be explained by instability of the receptors from malignant endometrium. Factors, including radiation therapy, plasma proteins, endogenous steroids, receptor degradation, tissue heterogeneity, and limited sample size, which influence the interpretation of receptor assay were systematically evaluated. In spite of these controls, it would be premature to conclude that the clinical observations indicate altered receptor from malignant tissue. Further studies are required on endometrial carcinoma which is free of normal tissue fragments. Clinically, nuclear receptor levels were highest in normal endometrium but decreased in samples of malignant endometrium as tumors became more anaplastic. The lowest nuclear binding activity was detected in samples of metastatic endometrial tissue (carcinoma). Hopefully, this nuclear receptor assay (which uses MPA because its dissociation was slower than progesterone) will provide data for correlating clinical response to therapy.^ieng

The role of progestins in the treatment of breast cancer.

In unselected populations of women, the progestins medroxyprogesterone acetate (MPA) and megestrol acetate (MA) have produced response rates of 14% to 31% in metastatic breast cancer, sparking new investigative activity to define their proper role. One proposed mechanism of action for progestins is that they interfere with replenishment of the cytoplasmic estrogen receptor. Although not binding to estrogen receptors, progesterone has been shown to decrease the quantity of estrogen receptor in target tissue. Prediction of response of metastatic breast cancer to progestins largely follows the conventional rules established for the selection of additive hormonal therapy. Little difference is seen between appropriate doses of MPA and of MA in reports of prognostic factors associated with tumor response. The presence of hormone receptors in tumor tissue may be the most significant predictor for response to progestins. Tumors that contain both estrogen and progesterone receptors will respond to progestins in over 61% of instances, whereas those with only one type of hormone receptor will respond 20% to 30% of the time. Response to MPA or MA is probably independent of the presence of progesterone receptor. Response rates to MA of around 30% have been noted in patients who had previously responded to tamoxifen and then progressed. Previous exposure to chemotherapy does not appear to jeopardize chances for response to MA. A limited number of randomized trials of tamoxifen versus MA show no significant response difference between the two therapies in breast cancer patients with similar prognoses.

Binding of progestins to the glucocorticoid receptor. Correlation to their glucocorticoid-like effects on in vitro functions of human mononuclear leukocytes.

A number of physiological and synthetic progestins were tested for their ability to compete with [3H]dexamethasone for the binding to the glucocorticoid receptor of human mononuclear leukocytes and their ability to elicit glucocorticoid-like effects on the same cells. As compared to the reference compound dexamethasone (relative receptor binding affinity defined as 100%), two potent synthetic progestins with a pregnane-type structure, megestrol acetate and medroxyprogesterone acetate, were found to display a considerable binding affinity towards the receptor (46 and 42%, respectively). The relative binding affinity of the naturally occurring ligand, cortisol, to the receptor was clearly lower (25%). The effective binding of medroxyprogesterone acetate to the glucocorticoid receptor was confirmed by direct binding studies utilizing a tritiated derivative of this steroid. No evidence for the existence of a specific progesterone receptor in human mononuclear leukocytes was obtained as judged by the results of competition experiments where a progesterone receptor-specific ligand [3H]Org 2058 was used. Medroxyprogesterone acetate and megestrol acetate also induced glucocorticoid-like effects on the lymphocyte functions. These included inhibition of the proliferative responses to the T-cell mitogens concanavalin A and phytohaemagglutinin and an enhanced accumulation of immunoglobulin secreting cells in pokeweed mitogen-stimulated cultures. The progestin effect appears to be mediated through a radiosensitive (suppressor) subpopulation of T lymphocytes. In contrast, the synthetic progestins related structurally to 19-nortestosterone, norethisterone and d-norgestrel, were virtually devoid of binding affinity towards the glucocorticoid receptor nor did they measurably influence the in vitro lymphocyte functions. These studies demonstrate that certain progestins in common clinical use probably possess inherent glucocorticoid activity and suggest that side effects attributable to this character (e.g. suppression of the pituitary-adrenal axis) might be expected when these compounds are used in pharmacological doses.

Medroxyprogesterone acetate and the nuclear uptake of testosterone and its metabolites by brain, pituitary gland and genital tract in male cynomolgus monkeys.

The synthetic progestin, medroxyprogesterone acetate (MPA), is used to treat male sex offenders, and it is also suppresses sexual activity in male monkeys. To examine the possibility that MPA may act as an anti-androgen in the primate brain, 4 intact male cynomolgus monkeys were given MPA (40 mg i.m.) once a week for 16 weeks, while 4 control males received i.m. injections of vehicle. All males were then castrated and 3 days later were given 3 mCi [3H]testosterone ([3H]T) i.v.; 1 h after injection males were killed, and radioactivity in nuclear pellets obtained from the hypothalamus (HYP), preoptic area (POA), amygdala (AMG), septum, pituitary gland and genital tract was analyzed by HPLC. Concentrations of [3H]T and [3H]dihydrotestosterone in nuclear pellets were 65-96% lower in MPA-treated males than in controls (P less than 0.001), but the aromatized metabolite, [3H]estradiol, which was the major form of radioactivity present in nuclear pellets from HYP, POA and AMG, was unchanged. There were no differences in concentrations of [3H]T in supernatants from the tissues of MPA-treated and control males. Because the reduced nuclear uptake of androgen in brain occurred in males whose androgen-dependent behavior had been suppressed by MPA treatments, it is proposed that MPA may have anti-androgenic effects at the level of the cell nucleus in brain regions that control behavior.

Membrane-initiated steroid signaling (MISS): genomic steroid action starts at the plasma membrane.

UNLABELLED: Plasma membrane (PM) steroid recognition sites are thought to be responsible only for rapid, non-genomic responses without any link to the nuclear receptor-mediated genomic effects of steroids. We focused on a PM "glucocorticoid-importer" (GC-importer) that imports GC into rat liver cells. This site interacts also with particular gestagens (progesterone, P; medroxyprogesterone, MP; ethynodiol, Ethy) and estrogens (ethinylestradiol, EE(2); mestranol), which do not bind to the nuclear GC receptor (GR). To elucidate the role of the GC-importer, we transfected a rat wild-type hepatocyte (CC-1) and a hepatoma cell line, unable to import GC (MH 3924), with a GC<-->GR-responsive luciferase (luc)-reporter gene. Selected steroids were tested for their ability to induce or inhibit luc expression. Corticosterone (B) and dexamethasone (Dex), but also the GC-antagonists cortexolone (Cortex), P and MP, induced luc. Even the PM-impermeable BSA-derivatives of B, Dex and Cortex did so to almost the same extent as the free steroids. MH 3924 cells respond stronger than CC-1 to luc inducing steroids. Luc expression was inhibited by RU 38 486, but also by EE(2) and Ethy. The thiol reactive mesylate-derivatives of B, Dex and Cortex induced to a considerably lesser extent than the free or BSA-steroids. The thiol reagent mersalyl blocks cellular entry of GC and inhibits luc induction in CC-1 cells. Incubation with EE(2) and B of PM-vesicles, isolated from liver cells, resulted in a decrease of the density of two 75 and 52kDa G-proteins reflecting a diminished exchange of GDP by GTP. CONCLUSION: the PM-residing GC-importer, now renamed "Steroid Hormone Recognition and Effector Complex" (SHREC) is an interdependent part of the complete GC signal propagation in which G-proteins are involved. Free SH-groups of SHREC are a prerequisite for genomic GC activity. Specific interactions between SHREC and GC-agonist/-antagonist trigger steroid-dependent signaling. However, import of the ligand into the cell terminates it. Thus, the PM-related non-genomic steroid responses are clearly linked to the GR-related genomic effects.

Androgenic, synandrogenic, and antiandrogenic actions of progestins.

In addition to their action on the uterus and vagina, progestins exert diverse metabolic effects on a variety of tissues. These actions include androgenic, synandrogenic, and antiandrogenic effects on androgen-responsive tissues of rats and mice. The androgenic and antiandrogenic effects of progestins have been demonstrated in multiple tissues. These actions appear to be mediated via the androgen receptor. A synandrogenic effect of progestins has also been detected in some tissues. However, there are few data to indicate how this response is mediated. Progestins may also alter androgen action indirectly through changes in steroid synthesis and metabolism. The overall biologic effect of a steroid may thus be determined by the sum of its actions on a variety of tissues.

Depo-medroxyprogesterone acetate compared with conjugated estrogens for the treatment of postmenopausal women.

Forty-three women who had undergone a natural or surgical menopause were randomized to receive either 0.625 mg of conjugated estrogens or an intramuscular injection of 150 mg of depo-medroxyprogesterone acetate (DMPA) for 25 days each month. Vasomotor symptoms were recorded before treatment for three weeks and weekly thereafter for three months. Serum estradiol (E2) and estrone (E1) were measured before and during the second month of treatment, as were urinary calcium, hydroxyproline, and creatinine levels. Vasomotor symptoms decreased significantly in both groups, and this reduction was of a similar magnitude with either treatment. Whereas 18% of patients in both groups did not have a reduction in vasomotor symptoms, of those women who did benefit, vasomotor symptoms decreased 61.5 +/- 7.5% with conjugated estrogens and 69.4 +/- 7.7% with DMPA. Eighteen percent of patients treated with conjugated estrogens reported no vasomotor symptoms whatsoever, as compared with 33% among those treated with DMPA. Serum estrone and estradiol increased in patients receiving conjugated estrogens, but were lower in women treated with depo-medroxyprogesterone acetate. Urinary calcium/creatinine and hydroxyproline/creatinine ratios were significantly lowered to the premenopausal range in women treated with conjugated estrogens and DMPA. There were no differences in these ratios when the two treatments were compared. Adverse side effects such as vulvovaginal complaints and weight gain were negligible in both groups and the complaints of dyspareunia were similar. The data from this short-term study suggest that depo-medroxyprogesterone acetate affords a suitable alternative to estrogen therapy for reducing vasomotor symptoms and may prevent bone resorption as well.

Comparative pharmacokinetics of medroxyprogesterone acetate administered by oral and intramuscular routes.

The present study was undertaken to elucidate (1) the relationship between plasma concentration of medroxyprogesterone acetate (MPA; Clinovir) administered by the PO and the IM routes; and (2) the relationship between dose and plasma concentration of MPA. Nineteen patients entered the study. In each patient the plasma concentration was monitored after a single PO and IM administration of MPA at the following dose levels: 100 mg (5 patients), 400 mg (5 patients), 800 mg (5 patients) and 1,200 mg (4 patients). The time interval between PO and the IM administration was 1 week. The results show (1) a very large interindividual variation in plasma concentration; (2) increasing plasma concentration with both PO and IM dose; (3) after the IM administration plasma levels are steady or increase slightly within the test period; (4) after the oral administration the concentration increases rapidly to reach a peak before 2-7 h and subsequently decreases again, peak concentrations being 2-10 times higher than after IM administration; and (5) within the test periods the plasma concentration x time (0-168 h) is comparable with the two methods of administration.

Medroxyprogesterone acetate plasma pharmacokinetics after intravenous administration in rabbits.

Medroxyprogesterone acetate (MAP) plasma pharmacokinetics was followed up in a total of 30 New Zealand rabbits after i.v. administration (0.1, 0.5, and 1.0 mg/kg) of either an aqueous suspension or a homogeneous solution of the drug in dimethylsulphoxide (DMSO). A well-defined triphasic decay of MAP plasma levels was noticeable in the animals treated with DMSO solutions. A delayed concentration peak was often present when aqueous suspensions were used, so if is not feasible to fit the experiment with simple polyexponential equations. Model-independent pharmacokinetic analysis (statistical moment theory) revealed a significant dependence of plasma clearance and mean residence time on the dose administered in both conditions.

Medroxyprogesterone acetate bioavailability after high-dose intraperitoneal administration in advanced cancer.

Administration of medroxyprogesterone acetate IP in advanced cancer with peritoneal metastases and ascitic effusion generates considerably higher drug plasma levels than those observed after PO or IM treatment. Comparison of areas under the time-concentration curves (AUC) with reference to the three administration routes indicates that after oral administration only 0.2%-17.4% (mean 5.7%; SD 3.77; 40 patients) of the administered dose is absorbed; after IM treatment a daily absorption of 0.7%-7.7% (mean 2.5%; SD 1.66; 30 patients) of the administered dose per injection site was computed.

Pharmacokinetic approach to the selection of dose schedules for medroxyprogesterone acetate in clinical oncology.

The pharmacokinetic and bioavailability properties of medroxyprogesterone acetate (MPA) after single PO and IM doses in man were used as a basis to predict, on a theoretical pharmacokinetic basis, the blood level profile of the drug during repeated dose administration with various dosage schedules. Because of the unusually long-lasting depot effect of IM MPA, a different build-up process of blood levels is expected during repeated IM or PO administration, and this should be taken into account when dose schedules for use in clinical oncology are selected. As regards the IM route, dose schedules based on 4 weeks' treatment with daily injections of 500-1,000 mg followed by a maintenance therapy with 1,000 mg/week are suggested, since they permit rapid achievement and maintenance of relatively high plasma levels. A similar plasma level profile can be obtained with oral MPA provided that daily doses twice as large as the IM doses are given during the first month of treatment and continued during the maintenance period. The serum levels observed in 25 patients with advanced breast cancer treated with MPA given IM or PO according to various dose schedules and recent literature data are very close to the serum level profiles predicted on a theoretical pharmacokinetic basis.

Hormone-releasing silastic intrauterine devices: effect or provera-releasing intrauterine devices on two species of primates.

Silastic intrauterine contraceptive devices (IUDs) 13 mm long and 1.07 mm in diameter could be inserted easily into patas monkey uteri which, like human uteri, expelled them. Addition of 10% Provera to these devices did not reduce the expulsion rate significantly in our study. Control devices had no effect on cycle length in rhesus monkeys. After insertion, the active IUDs frequently caused a delay in onset of menstruation; however, cycles did occur with the device in situ, and normal-length cycles were resumed following removal of the device. A short period of rapid release (almost 35% of the total amount) of Provera from the device was followed by a longer period of sustained release of low levels of the hormone. Even 9 mug/day were sufficient to maintain a decidual reaction in the endometrium of the rhesus monkey. The drug could not be detected in the blood stream at 3,6, or 12 hours in patas monkeys or at 1 or 2 months in rhesus monkeys and so may never have reached the systemic circulation. Devices currently under study in baboons catain Provera or one of three other steroids to determine whether these compounds improve retention rates as well as meet the other two criteria set for the ideal IUD incorporation, for unless we meet this first criterion we can never achieve, let alone test, the others.

A preliminary pharmacokinetic and pharmacodynamic evaluation of depot-medroxyprogesterone acetate and norethisterone oenanthate.

PIP: 2 populations attending WHO centers, one in Sweden and one in India, participated in a comparative, pilot trial of 2 increasingly popular injectable progestin-only female contraceptives, Depo-Provera and Norigest. The purpose of the study was to assess the pharmacokinetic and pharmacodynamic properties of the 2 formulations (depot medroxyprogesterone acetate and norethisterone enanthate). Differences were found between Swedish women and Indian women in their reactions to the 2 drugs: 1) Norigest was detectable in blood samples a significantly shorter time after injection of the agent in Indian women than in Swedish women; this difference was not apparent with Depo-Provera. 2) Although there was no difference at the 2 centers in the time of ovulation return for subjects receiving Norigest, 0 of 4 Swedish women ovulated more than 156 days after Depo-Provera injection, whereas all 4 Indian women ovulated within 73 days of Depo-Provera injection; in the Swedish women, the levels of medroxyprogesterone were undetectable at time of return to ovulation, whereas Indian women had levels of .6 ng/ml when ovulation resumed. 3) In both cultures, Depo-Provera users had significantly more episodes of bleeding and spotting than Norigest users. This preliminary report emphasizes the variety of responses possible to injection of different contraceptive progestins among various populations and points to the need for further culturally comparative studies.^ieng

Effects of progesterone, progestogens, and danazol on the specific cortisol binding in human plasma.

The interaction of medroxyprogesterone acetate (MPA) with cortisol binding to corticosteroid-binding globulin (CBG) was studied with the use of an aqueous two-phase system with polyethylene glycol and dextran for equilibrium partition. Competitive binding analyses were also performed for progesterone (P), levonorgestrel, norethisterone, danazol, and tamoxifen. P and danazol were found to exert cortisol displacing activity, whereas MPA and the other tested compounds had no such effect. The glucocorticoid effects reported for MPA could not be explained by displacement. In general, P serum concentrations are lower than those of cortisol, and most binding sites on CBG are occupied by the glucocorticoid. At high P levels displacement and an increase in free cortisol may occur. Danazol displacement of cortisol is hampered by its pronounced albumin binding. In conclusion, none of the tested compounds should increase free and biologically active cortisol during normal clinical treatment.

Pre-optic and hypothalamic neurons accumulate [3H]medroxyprogesterone acetate in male cynomolgus monkeys.

Medroxyprogesterone acetate (MPA) is a synthetic progestin that is reported to be effective in the treatment of paraphilic behavior, including paraphilic aggression, in men. The mechanisms and sites of action for its behavioral effects are not known. Thaw-mount autoradiography was used to help identify sites in the brain at which MPA may act in a male primate. Two adult, castrated male cynomolgus monkeys were administered [3H]MPA and killed one hour later. Radioactivity was concentrated in the nuclei of many neurons in the medial preoptic nucleus (n.), anterior hypothalamic area, ventromedial hypothalamic n., and arcuate n. Virtually no labeled cells were observed in the bed n. of the stria terminalis, lateral septal n., or amygdala. Analysis by high performance liquid chromatography of brain samples from the same animals demonstrated that 84% of the extractable radioactivity in cell nuclei from the hypothalamus and preoptic area was in the form of unmetabolized [3H]MPA. The localization of MPA-concentrating neurons in regions of the brain known to be implicated in regulating both sexual behavior and pituitary function suggests that, among other sites of action, MPA may act directly upon the brain.

Isolation and partial synthesis of a new metabolite of medroxyrogesterone acetate.

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.