Characterization of the period of sensitivity of fetal male sexual development to vinclozolin.
(33/1203)
Vinclozolin is a fungicide whose metabolites are androgen receptor (AR) antagonists. Previous work in our laboratory showed that perinatal administration of vinclozolin to rats results in malformations of the external genitalia, permanent nipples, reduced anogenital distance (AGD), and reduced seminal vesicle, ventral prostate, and epididymal weights. The objectives of this study were to determine the most sensitive period of fetal development to antiandrogenic effects of vinclozolin and to identify a dosing regime that would induce malformations in all of the male offspring. Pregnant rats were dosed with 400 mg vinclozolin/kg/day on either GD 12-13, GD 14-15, GD 16-17, GD 18-19, or GD 20-21, or with corn oil (2.5 ml/kg) from GD 12 through GD 21 (Experiment 1). All 2-day periods in which significant effects were produced were included in an extended dosing period, GD 14 through GD 19, in which pregnant rats were dosed with 200 or 400 mg vinclozolin/kg (Experiment 2). In Experiment 1, significant effects of vinclozolin were observed in rats dosed on gestation days (GD) 14-15, GD 16-17, and GD 18-19, while the most significant effects were observed in rats treated on GD 16-17. These effects include reduced AGD; presence of areolas, nipples, and malformations of the phallus; and reduced levator ani/bulbocavernosus weight. In contrast, ventral prostate weight was reduced only in the GD 18-19 group. The expanded dosing regime (Experiment 2) increased the percentage of male offspring with genital malformations (> 92%), and retained nipples (100%), further reduced the weight of the ventral prostate, and reduced the weight of the seminal vesicles. In addition, malformations were more severe and included vaginal pouch and ectopic/undescended testes. The latter was induced only in the 400 mg/kg group. These data indicate that the reproductive system of the fetal male rat is most sensitive to antiandrogenic effects of vinclozolin on GD 16 and 17, although effects are more severe and 100 % of male offspring are affected with administration of vinclozolin from GD 14 through GD 19. (+info)
Early results of LH-RH agonist treatment with or without chlormadinone acetate for hormone therapy of naive localized or locally advanced prostate cancer: a prospective and randomized study. The Prostate Cancer Study Group.
(34/1203)
BACKGROUND: The majority of patients with localized and some cases of locally advanced prostate cancer undergo radical prostatectomy. However, radical prostatectomy cannot always be selected for those patients. In this situation, primary hormone therapy is an alternative treatment option. We have designed a prospective randomized study of the effects of primary hormone therapy for such patients. METHODS: A total of 151 patients with T1b, T1c, T2a, T2b or T3a prostate cancer who were not scheduled for radical prostatectomy were enrolled into this study. Patients were randomly allocated into two groups; Group I received luteinizing hormone-releasing hormone (LH-RH) agonist monotherapy (leuprorelin acetate depot, 3.75 mg monthly) and Group II received LH-RH agonist in combination with chlormadinone acetate (100 mg/day). Effects on serum prostate-specific antigen level, progression-free survival and survival were observed for 2 years. RESULTS: The reasons why radical prostatectomy was not scheduled were poor risk for surgery (38%), patient's wish (32%) and physician's recommendation (30%). After 12 weeks of treatment, 49% of the patients in both groups showed a complete response (CR). Of the patients showing a partial response (PR) after 12 weeks of treatment, 25% in Group I and 52% in Group II improved to CR 1 year later (p<0.05). Group II showed a longer progression-free survival (p <0.05). Progression-free survival rates were 62% (Group I) and 91% (Group II) in T2b patients and 43% (Group I) and 73% (Group II) in T3 patients. Only one patient in each group died from prostate cancer. CONCLUSIONS: Early primary hormone therapy is a reasonable treatment option for localized or locally advanced prostate cancer patients if radical prostatectomy was not scheduled. Chlormadinone acetate showed an additive effect with LH-RH agonist, at least in 2 years' observation. (+info)
Oral, but not transdermal, administration of estrogens lowers tissue-type plasminogen activator levels in humans without affecting endothelial synthesis.
(35/1203)
Oral estrogen administration decreases plasma levels of tissue-type plasminogen activator (tPA), which may be explained by a decrease in endothelial tPA synthesis, an increase in its hepatic clearance, or both. In the present study, we determined (1) differences between oral (ie, via the liver) ethinyl estradiol and transdermal (ie, systemic) 17beta-estradiol administration on plasma antigen levels of tPA and plasminogen activator inhibitor type-1 before and after 4 months of hormone administration and (2) effects on endothelial tPA synthesis, by measuring the local increase in plasma tPA during venous occlusion of the upper extremity. Thirty transsexual males (median age 32 years, range 20 to 44 years ) were randomly assigned to either oral ethinyl estradiol (n=15) or transdermal 17beta-estradiol (n=15); both treatments included the antiandrogen cyproterone acetate (CA). Ten males were treated with CA alone. Seventeen transsexual females (median age 27 years, range 18 to 37 years) were treated with intramuscular testosterone esters. Only oral ethinyl estradiol plus CA but neither transdermal 17beta-estradiol plus CA, nor oral CA, nor parenteral testosterone lowered plasma tPA and plasminogen activator inhibitor-1 (P<0.001 for both). tPA release during venous occlusion was not affected by oral ethinyl estradiol plus CA in males (P=0.52) or by parenteral testosterone in females (P=0.89). These data are consistent with a previous observation, in rodents, that the decrease in tPA after oral estrogen administration can be explained by an increase in hepatic tPA clearance, leaving endothelial tPA synthesis unchanged, and suggest that these mechanisms also explain the decrease in tPA in humans. (+info)
Androgen receptor localisation and turnover in human prostate epithelium treated with the antiandrogen, casodex.
(36/1203)
In vitro models of normal and malignant human prostate are currently limited to a few well established cell lines that, with a single exception (LNCaP), fail to express the androgen receptor (AR) - a common characteristic of prostatic epithelium grown in culture. To investigate the molecular mechanism of action of the non-steroidal antiandrogen Casodex (bicalutamide) against wild-type AR, we have established a transient AR expression model in non-tumorigenic prostate cells of both epithelial and mesenchymal origin. In this model, both dihydrotestosterone and Casodex can effectively transport the AR protein into the nucleus of prostate cells. Whereas the natural ligand, dihydrotestosterone, stabilises the receptor, the AR is rapidly degraded at a nuclear location when the transfected cells are treated with Casodex. In contrast, whereas the mutant AR in the LNCaP line is also degraded on Casodex treatment over the same time period, its intracellular targeting is defective. (+info)
Effects of androgens, progesterone and their antagonists on the developmental competence of in vitro matured bovine oocytes.
(37/1203)
The aim of the present study was to determine whether androgens and progesterone influence the in vitro maturation of bovine oocytes as assessed by cleavage rates and competence to form blastocysts after in vitro fertilization. Bovine cumulus-oocyte complexes were cultured (n = 20 per drop) for 22-24 h at 38.5 degrees C in TCM-199 medium supplemented with 10% oestrous cow serum, eCG (2.5 iu ml(-1)) and a range of treatments that included aromatizable (testosterone; 100 nmol l(-1)) and non-aromatizable (dihydrotestosterone; 100 nmol l(-1)) androgens, an androgen antagonist (flutamide; 36 micromol l(-1)), progesterone (300 nmol l(-1)) and a progesterone antagonist (mifeprisone, RU486; 100 nmol l(-1)). Production of inhibin A, total alpha-subunit, activin A and follistatin by each group of cumulus-oocyte complexes was also measured, since inhibin-related peptides have been implicated as modulators of oocyte maturation and their production may be influenced by steroids and anti-steroids. Both testosterone and dihydrotestosterone increased oocyte cleavage rate (25%; P < 0.01) and dihydrotestosterone also increased (24%; P < 0.05) the proportion of oocytes that reached the >/= eight-cell stage. However, neither androgen affected blastocyst yield, or the proportion of blastocysts that hatched. The stimulatory effect of dihydrotestosterone on cleavage rate was reduced by flutamide but the anti-androgen had no effect when tested alone. Treatment with testosterone, but not dihydrotestosterone, decreased (P < 0.05) endogenous follistatin and increased (P < 0.05) the activin A:follistatin ratio in maturation medium. Concentrations of inhibin A, total alpha-subunit and activin A were not affected significantly by androgen or flutamide. Addition of progesterone or the anti-progestin mifepristone to cumulus-oocyte complexes had no effect on cleavage rate. However, progesterone reduced by approximately 40% (P < 0.05) the proportions of both total oocytes and cleaved oocytes that formed blastocysts. This effect was partially reversed by mifepristone. Neither progesterone nor mifepristone affected inhibin A, activin A or follistatin production. However, total alpha-subunit concentration was significantly greater in the progesterone-treated group than in the controls (50%; P < 0.05), indicating that the negative effect of progesterone on blastocyst yield may be mediated by increased inhibin alpha-subunit expression by cumulus cells. (+info)
Anti-tumour effects and pharmacokinetic profile of 17-(5'-isoxazolyl)androsta-4,16-dien-3-one (L-39) in mice: an inhibitor of androgen synthesis.
(38/1203)
17-(5'-Isoxazolyl)androsta-4,16-dien-3-one (L-39), a novel androstene derivative, was synthesized and evaluated in vitro and in vivo. L-39 showed potent and non-competitive inhibition of human testicular microsomal 17alpha-hydroxylase/C(17,20)-lyase with an IC50 value of 59 nM and Ki of 22 nM. L-39 also showed potent and competitive inhibition of 5alpha-reductase in human prostatic microsomes with IC50 and Ki values of 33 and 28 nM respectively. L-39 (5 microM) has also been shown to manifest anti-androgenic activity in cultures of human prostate cancer cell lines (LNCaP) by preventing the labelled synthetic androgen R1881 (5 nM) from binding to the androgen receptors. Androgen-dependent human prostate cancer xenografts (PC-82) were grown in nude mice and the effects of L-39 (50 mg kg(-1) day(-1)) on tumour growth and prostate-specific antigen (PSA) levels were determined after 28 days. L-39 significantly (P < 0.01) diminished tumour growth and wet weights to a similar extent as castration or flutamide treatment. L-39 also significantly (P < 0.01) reduced serum PSA levels by more than 80% in the mice bearing human prostate cancer xenografts. Pharmacokinetic studies were also conducted in male Balb/c mice. After subcutaneous administration of a single bolus dose, L-39 was rapidly absorbed into the systemic circulation. Peak plasma levels occurred at 0.75 h and then declined with a t(1/2) of 1.51 h. The bioavailability of L-39 after subcutaneous administration was 28.5%. These results demonstrate that L-39 is a potent inhibitor of androgen synthesis and is effective in reducing the growth of human prostate cancer xenografts in nude mice. Although improvements in the bioavailability are necessary, L-39 is a potential lead compound with this profile as an inhibitor of prostate cancer growth. (+info)
Cellular and molecular mechanisms of action of linuron: an antiandrogenic herbicide that produces reproductive malformations in male rats.
(39/1203)
Antiandrogenic chemicals alter sex differentiation by several different mechanisms. Some, like flutamide, procymidone, or vinclozolin compete with androgens for the androgen receptor (AR), inhibit AR-DNA binding, and alter androgen-dependent gene expression in vivo and in vitro. Finasteride and some phthalate esters demasculinize male rats by inhibiting fetal androgen synthesis. Linuron, which is a weak competitive inhibitor of AR binding (reported Ki of 100 microM), alters sexual differentiation in an antiandrogenic manner. However, the pattern of malformations more closely resembles that produced by the phthalate esters than by vinclozolin treatment. The present study was designed to determine if linuron acted as an AR antagonist in vitro and in vivo. In vitro, we (1) confirmed the affinity of linuron for the rat AR, and found (2) that linuron binds human AR (hAR), and (3) acts as an hAR antagonist. Linuron competed with an androgen for rat prostatic AR (EC(50) = 100-300 microM) and human AR (hAR) in a COS cell-binding assay (EC(50) = 20 microM). Linuron inhibited dihydrotestosterone (DHT)-hAR induced gene expression in CV-1 and MDA-MB-453-KB2 cells (EC(50) = 10 microM) at concentrations that were not cytotoxic. In short-term in vivo studies, linuron treatment reduced testosterone- and DHT-dependent tissue weights in the Hershberger assay (oral 100 mg/kg/d for 7 days, using castrate-immature-testosterone propionate-treated male rats; an assay used for decades to screen for AR agonists and antagonists) and altered the expression of androgen-regulated ventral prostate genes (oral 100 mg/kg/d for 4 days). Histological effects of in utero exposure to linuron (100 mg/kg/d, day 14-18) or DBP (500 mg/kg/d, day 14 to postnatal day 3) on the testes and epididymides also are shown here. Taken together, these results support the hypothesis that linuron is an AR antagonist both in vivo and in vitro, but it remains to be determined if linuron alters sexual differentiation by additional mechanisms of action. (+info)
Exclusive androgenic effect of dehydroepiandrosterone in sebaceous glands of rat skin.
(40/1203)
In order to analyze the hormonal effects of dehydroepiandrosterone (DHEA) in skin sebaceous glands, the precursor steroid was administered to ovariectomized (OVX) female Sprague-Dawley rats at a dose of 30 mg applied on the dorsal skin, twice daily, for 3, 6 and 12 months. In a parallel experiment, female OVX rats were treated with DHEA at the same daily percutaneous dose of 30 mg, alone or in combination with the antiandrogen Flutamide or the pure antiestrogen EM-800, for 12 months, in order to determine the androgenic and/or estrogenic components of DHEA action. Treatment of female OVX rats with DHEA resulted in a similar mild to moderate hyperplasia of the sebaceous glands of both dorsal (site of application) and ventral skin, as illustrated by an increase in the number and size of the acini. The above-indicated effects were observed at all time intervals studied, beginning at 3 months of treatment, and they were not further increased after longer term administration of DHEA (for 6 and 12 months). The addition of Flutamide to DHEA treatment completely prevented the DHEA-induced changes in the sebaceous glands, whereas the antiestrogen EM-800 had no effect. The present data indicate an exclusive androgenic stimulatory action of DHEA on the sebaceous glands, thus pointing out the importance of local intracrine DHEA transformation into androgens for skin anatomical integrity and function, while showing that estrogens, if active in rat skin, do not originate from DHEA. (+info)