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The study was to investigate the effect of gestrinone on the growth of human uterine leiomyoma cells and on the levels and activity of p38, Src and estrogen receptor alpha (ERα). Human uterine leiomyoma cells were cultured and treated with dimethylsulfoxide (DMSO) or a gestrinone concentration gradient. Morphological changes were observed and apoptosis was evaluated. Levels of p38 and phosphorylated-p38 (pp38) were assayed by enzyme-linked immunosorbent assay (ELISA). Levels of ERα and Src were analyzed using real-time RT-PCR and Western blotting. The result showed that gestrinone significantly inhibited the growth of cultured human uterine leiomyoma cells in a concentration- and time-dependent manner, with a 50% inhibitory concentration (IC(50)) value and corresponding 95% confidence intervals (CI) of 43.67 (23.46∼81.32), 27.78 (12.51∼61.68) and 15.25 (7.17∼32.43) μmol/L at 20, 40 and 60h, respectively. Compared with control-treated leiomyoma cells, gestrinone significantly reduced both the expression of ERα (P<0.05) and the levels of phospho-Ser167-ERα (P<0.05). Gestrinone also markedly suppressed the level of phospho-Tyr416-Src (P<0.05). Moreover, gestrinone significantly increased the ratio of phospho-p38/p38 mitogen-activated protein kinase (MAPK) (P<0.05). However, no significant increase in apoptosis or cell cycle arrest was observed (P>0.05) in response to the tested concentrations of 0.1 to 3.0μmol/L. As a conclusion, gestrinone suppresses the proliferation of uterine leiomyoma cells mainly by regulating the activity of ERα/Src/p38 MAPK in a concentration-dependent manner at a low concentration of 0.1∼3.0μM, but not significantly regulating apoptosis. Gestrinone opposes the growth of uterine leiomyoma through multiple genes., (Copyright © 2012. Published by Elsevier SAS.)

For a long time, athletes have used androgenic anabolic steroids (AASs) in an inappropriate and veiled manner with the aim of improving exercise performance or for cosmetic purposes. Abuse of AASs triggers adverse effects such as hepatocarcinogenesis, heart attacks, and aggressive behavior. However, AAS-induced toxicity is not completely understood at the molecular level. In the present study, we showed, by performing a dioxin response element (DRE)-luciferase reporter gene assay, that tetrahydrogestrinone (THG), a popular and potent androgen receptor agonist, has dioxin-like effects. In addition, we showed that THG increased cytochrome P-450 1A1 (CYP1A1) mRNA and protein levels, and enzyme activity. The gene encoding CYP1A1 is involved in phase 1 xenobiotic metabolism and a target gene of the aryl hydrocarbon receptor (AhR). Using the AhR antagonist CH-223191, we also examined whether the effects of THG on DRE activation depended on AhR. Our results suggest that synthetic anabolic steroids may have dioxin-like side effects that can disturb endocrine systems and may cause other side effects including cancer through AhR., (Copyright © 2012. Published by Elsevier Ltd.)

Background: A previous investigation showed that among 120 healthy women treated with a single oral dose of gestrinone for emergency contraception (EC), there was only one pregnancy. The effect of a single oral dose of gestrinone given for EC on ovarian function and endometrial development was studied., Study Design: Healthy fertile women were randomly assigned to Group A (n=8) or Group B (n=7). Gestrinone 5 mg was orally administered to each woman before (Group A) or after (Group B) ovulation. The day of ovulation was determined by transvaginal ultrasound and by urinary luteinizing hormone (LH) measured by enzyme immunoassay (One Step LH Ovulation Test). An endometrial biopsy was performed during implantation. Endometrial maturation and expression of markers of endometrial receptivity were analyzed. The tested markers were integrins alpha(1)beta(1), alpha(4)beta(1) and beta(3). Serum estradiol (E(2)) and progesterone (P) levels in serum were determined by radioimmunoassay, and estradiol receptors and progesterone receptors (PRs) in the endometrium were assessed by immunohistochemistry., Results: Gestrinone administered during the periovulatory period did not affect follicular development, ovulation, menstrual cycle length and E(2) and P levels but decreased the expression of PR in the endometrium. Integrin alpha(4)beta(1) tended to increase after treatment with gestrinone without reaching statistical significance., Conclusion: The mode of action of gestrinone used for EC is probably inhibition of implantation by acting on the endometrium rather than inhibition of ovulation.

Aim: To investigate the effect of gestrinone on uterine leiomyomas and the expression of c-Src, estradiol receptors (ER), and progesterone receptors (PR) in a guinea pig model., Methods: After being oophorectomized, the guinea pigs were allocated into random groups. The model group was treated with estradiol benzoate (E2) for 16 weeks. In the gestrinone-treated groups, the animals were treated with E2 for 6 weeks in advance, and then in combination with gestrinone for 10 weeks. Histological examination was performed to evaluate whether there were leiomyoma features in the animals. The protein levels of c-Src, phospho-( 416)Src, ER, and PR were assayed by Western blotting and an immunohistochemical method., Results: Morphological changes were observed in the myometrium of the guinea pig model, including an increase of uterine weights, proliferation of uterine smooth muscles, and the formation of nodules. High protein levels of c-Src, phospho- 416Src, ER, and PR were observed in the myometrium of the guinea pig model. In the gestrinone-treated group, there were no nodules observed. The histological features of the myometrium were similar to that of the control group. Low protein levels of c-Src, phospho-(416 )Src, ER, and PR were observed in the gestrinonetreated group., Conclusion: The upregulation of c-Src and phospho-(416 )Src indicated that the activity of c-Src is augmented in the uterine leiomyoma model. c-Src was associated with the formation of uterine leiomyomas in the model, and gestrinone markedly suppressed the growth of uterine leiomyomas in the model. Gestrinone inhibited not only the protein expression of ER and PR, but also c-Src and the autophosphorylation of c-Src in the guinea pig leiomyoma model.

Tetrahydrogestrinone (THG) is a steroid recently identified to be misused as doping agent. However, the knowledge on functions of this substance in humans or animal models is rather limited. Therefore, it was our aim to further characterize the pharmacological profile of THG and identify potential adverse side effects. THG was synthesized, the purity was confirmed and its biological activity was tested. The potency of THG to transactivate AR dependent reporter gene expression was two orders of magnitude lower compared to dihydrotestosterone. THG binds with high affinity but unselective to the androgen (AR), progesterone (PR), glucocorticoid (GR) and mineralocorticoid (MR) receptor. Treatment of orchiectomised rats with THG resulted in a stimulation of prostate, seminal vesicle and levator ani muscle, indicating androgenic and anabolic properties. In the liver THG, in contrast to testosteronepropionate (TP), down regulates the expression of the GR dependent tyrosine aminotransferase gene (TAT). In summary, our results demonstrate that THG is not a specific AR agonist. THG exhibits a high binding affinity to all tested steroid hormone receptors and binds with highest affinity to the GR. Our in vivo data are indicative of an anabolic and androgenic potency of THG, but the repression of TAT demonstrates that THG also interferes with the glucocorticoid hormone system. Therefore, it is conceivable that an intake will result in adverse side effects.

The discovery of tetrahydrogestrinone (THG) abuse by several elite athletes led the U.S. Congress to declare it a controlled substance, although conclusive evidence of its anabolic/androgenic activity is lacking. We determined whether THG affects myogenic differentiation and androgen receptor (AR)-mediated signaling, whether it binds to AR, and whether it has androgenic and anabolic effects in vivo. Accordingly, we measured the dissociation constant for THG with a fluorescence anisotropy assay using recombinant AR-ligand binding domain. The AR nuclear translocation and myogenic activity of androstenedione were evaluated in mesenchymal, multipotent C3H10T1/2 cells. We performed molecular modeling of the THG:AR interaction. The androgenic/anabolic activity was evaluated in orchidectomized rats. THG bound to AR with an affinity similar to that of dihydrotestosterone. In multipotent C3H10T1/2 cells, THG upregulated AR expression, induced AR nuclear translocation, dose dependently increased the area of myosin heavy chain type II-positive myotubes, and up-regulated myogenic determination and myosin heavy chain type II protein expression. The interaction between AR and the A ring of THG was similar to that between AR and the A ring of dihydrotestosterone, but the C17 and C18 substituents in THG had a unique stabilizing interaction with AR. THG administration prevented the castration-induced atrophy of levator ani, prostate gland, and seminal vesicles and loss of fat-free mass in orchidectomized rats. We conclude that THG is an anabolic steroid that binds to AR, activates AR-mediated signaling, promotes myogenesis in mesenchymal multipotent cells, and has anabolic and androgenic activity in vivo. This mechanism-based approach should be useful for rapid screening of anabolic/androgenic agents.

Objective: To investigate the effects of gestrinone on growth and apoptosis, as well as the expression of phosphatase and tension homologue deleted on chromosome 10 (PTEN) in isolated ectopic endometrium cells in vitro and the underlying mechanisms., Methods: Ectopic endometrium cells were cultured and exposed to gestrinone of different doses of 0, 10(-6) and 10(-4) mol/L respectively. The inhibition of the cells during 48 hours was determined by methylthiazolyl tetrazolium (MTT) assay, and the cell growth curve was made. Gestrinone was administered to the cells and at 24 hours the morphological changes were observed by transmission electron microscopy and the apoptosis rate, cell cycle and PTEN expression were monitored by flow cytometry (FCM) at the same time., Results: Gestrinone at different concentrations could inhibit the growth and proliferation of ectopic endometrium cells in a dose- and time-dependent manner. The inhibition rate of cell growth after exposed to gestrinone for 8, 16, 24, 32, 40 and 48 h was 99.6%, 87.3%, 79.8%, 62.3%, 51.7% and 44.2% in the 10(-6) mol/L group, and 99.2%, 77.1%, 69.6%, 51.1%, 33.7% and 23.6% in the 10(-4) mol/L group (P < 0.05), and cell growth curve was changed accordingly. After 24 hour exposure to gestrinone from 10(-6) to 10(-4) mol/l, apoptotic changes of cells were observed under transmission electron microscope. FCM showed that after the exposure to gestrinone, the apoptotic rate of ectopic endometrium cells was 1.3% in 10(-6) mol/L group and 15.0% in 10(4) mol/L group. It was significantly increased when compared with the 0 mol/L group, the apoptotic rate of which was 0% (P < 0.05). The level of PTEN expression of the ectopic endometrium cells was 60.6% after treated with 0 mol/L gestrinone, while in 10(-6) and 10(-4) mol/l groups the level of PTEN expression was increased to 75.3% and 85.7%, significantly higher than that of the 0 mol/L group (P < 0.05)., Conclusion: Gestrinone can significantly inhibit the growth and proliferation of ectopic endometrium cells, and this effect was related to increase of PTEN expression.

Tetrahydrogestrinone (THG) was recently identified as a novel steroid used illicitly to improve athletic performance. Although its structure is closely related to gestrinone, a 19-nor progestin, and resembles that of trenbolone, THG was never marketed, so information on its hormonal properties is not known. In this study, we demonstrate that THG is a highly potent androgen and progestin in a yeast-based in vitro bioassay system expressing human androgen and progesterone receptors. It has no estrogenic activity and no antagonism for any of the three steroid receptor classes.

Objective: Our purpose was to determine and compare the efficacy and hormonal and metabolic effects of 1.25 mg with 2.5 mg of gestrinone given twice a week in the treatment of mild and moderate pelvic endometriosis., Study Design: A phase II, prospective, randomized, double-blind study involving 11 patients given gestrinone 1.25 mg (five patients) or 2.5 mg (six patients) orally twice a week for 24 weeks was performed. Revised American Fertility Society scores were determined by laparoscopy before and at the end of treatment. Serum hormone (free thyroxine, free testosterone, estradiol, progesterone, follicle-stimulating hormone, luteinizing hormone), sex hormone binding globulin, and lipid concentrations were measured before, throughout, and for 6 months after treatment. Quantitated computerized tomography of thoracic 12 through lumbar 4 vertebral bodies were determined before, at the end of, and 6 months after treatment., Results: Gestrinone 2.5 mg significantly reduced the endometriosis implant score from 10.3 +/- 2.8 to 3.8 +/- 0.8 (p = 0.05). Both doses significantly reduced serum progesterone and sex hormone binding globulin levels. Estradiol, free testosterone, free thyroxine, follicle-stimulating hormone, and luteinizing hormone levels were not significantly affected. Spinal bone increased significantly by 7.1% with 2.5 mg but lost significantly by 7.1% with 1.25 mg gestrinone; these changes had not reversed completely 6 months after stopping treatment., Conclusions: In mild to moderate pelvic endometriosis 2.5 mg of gestrinone twice a week was more effective and had a more positive effect on bone mass than did 1.25 mg of gestrinone.

Recent evidence suggested that periovulatory treatment with an immunomodulatory agent such as verapamil might be an effective alternative to conventional treatment for endometriosis-associated subfertility. In particular, it has been reported that the drug might reduce the accentuated macrophage peritoneal activation demonstrated in patients with endometriosis. In this study, we compared the effect of the calcium antagonist verapamil with those of gestrinone, danazol and testosterone on human monocyte phagocytosis in an attempt to evaluate any significant differences in their ability to influence a parameter of cell inflammatory activation. Peripheral blood monocytes were isolated from 37 healthy women. Monocyte function was determined by phagocytosis of fluorescent microspheres after an overnight incubation in the presence or absence of the various agents. This study indicates that verapamil at the pharmacological concentration of 0.4 micrograms/ml, the systemic level in patients taking 40-80 mg/8 h p.o., significantly inhibits monocyte function. A lower immunosuppressive but still significant effect was achieved in this assay system with gestrinone at a concentration of 3 x 10(-8) M). The pharmacological concentration of danazol (10(-6) M) and the physiologic concentration of testosterone (10(-8) M) did not significantly affect this immunologic test system. These results provide evidence that verapamil is able to exert a slightly greater immunosuppressive effect than steroidal drugs on monocyte phagocytosis. However, due to the small differences observed, further studies on the biological mechanism of the drug seem to be necessary to completely elucidate its potential role in endometriosis-associated subfertility.

Clinical and experimental evidence supports the hypothesis that some steroidal drugs with androgenic effects might influence the immune system. The present study investigated whether gestrinone is able to affect macrophage and lymphocyte activity in vitro. Macrophage function was determined by phagocytosis of fluorescent microspheres, whilst lymphocyte proliferation was assessed by cell counting. Macrophage phagocytosis was evaluated after an overnight incubation in the presence or absence of gestrinone at serial dilutions; lymphocyte proliferation was detected in basal conditions and after stimulation with Concanavalin A (Con A) in the presence or absence of gestrinone. The results of this study showed that gestrinone significantly inhibited macrophage phagocytosis at the concentrations of 10(-8), 3 x 10(-8) and 10(-7) M. Furthermore, a significant suppression of lymphocyte blastogenesis was observed when lymphocytes were incubated with gestrinone at the concentration of 10(-7) M for 6 days. The biological significance of gestrinone as an inhibitor of immune functions under experimentally defined conditions is discussed in relation to its potential mechanism for fertility enhancement.

The in vivo effects of gestrinone (R2323) and medroxyprogesterone acetate (MPA) on the estrogen production by rat ovaries were investigated. Hypophysectomized immature female rats treated with 2.5 or 5 IU of pregnant mare serum gonadotropin (PMS) were daily given vehicle only, gestrinone (0.5 mg/kg body weight) or MPA (10 mg/kg body weight), and the activities of 3 beta-hydroxysteroid dehydrogenase, 17 alpha-hydroxylase, 17, 20-lyase, 17 beta-hydroxysteroid dehydrogenase and aromatase in ovaries of these rats were measured. Gestrinone suppressed the 3 beta-hydroxysteroid dehydrogenase activity and increased activities of 17 alpha-hydroxylase, 17, 20-lyase and aromatase in ovaries stimulated by 5 IU of PMS, while MPA suppressed activities of 17 alpha-hydroxylase and aromatase in these ovaries. On the other hand, the aromatase activity in ovaries stimulated by 2.5 IU of PMS was suppressed by gestrinone and increased by MPA, and neither gestrinone nor MPA affected the production of aromatizable androgens from progesterone by these ovaries. Thus, gestrinone and MPA administrated in vivo showed divergent influences on steroidogenic enzyme activities in ovaries, but they did not affect the serum concentration of estradiol-17 beta. The present results suggest that neither gestrinone nor MPA reduced estrogen production by the rat ovary under the gonadotropin stimulation although they influenced some process of its steroidogenesis.

Gestrinone has a biophysical antiestrogenic effect. But the mechanism of its antiestrogenic effect is not clear. Gestrinone blocked the increase of estrogen binding of nuclear type II sites and uterine weight in the estrogen-treated immature rabbit. Competitive assays indicated that gestrinone, at low concentrations (0.4 approximately 4 nM), inhibited [3H]-estradiol binding to nuclear type II sites. This inhibitory effect was the same as the addition of 20 microM diethyl-stilbestrol. This inhibition with gestrinone on [3H]-estradiol binding to nuclear type II sites appeared only when used at concentrations less than an equivalent molar of [3H]-estradiol. Time course analysis of the gestrinone binding inhibition showed that within the first 6 min gestrinone did not inhibit specific [3H]-estradiol binding to nuclear type II sites. This gestrinone-mediated inhibition was not observed in soluble fractions such as the cytosolic and KCl-extracted nuclear binding sites. These results suggest that gestrinone acts primarily on the nuclear fraction and then it operates the inhibitory mechanism on estradiol binding to nuclear type II sites.

The present study was designed to determine the effects of gestrinone (R2323) in the process of follicle rupture and oocyte maturation and degeneration in an in vitro perfused rabbit ovary model. In the first experiment, R2323 at 10(2), 10(3), or 10(4) ng/ml was added to the perfusate of one ovary. The contralateral control ovary was perfused simultaneously with medium alone. Thirty minutes after the onset of perfusion, 50IU of human chorionic gonadotropin (hCG) was added to the perfusate of both ovaries. All ovaries exposed to R2323 plus hCG or hCG alone ovulated. The addition of R2323 to the perfusate did not affect the ovulatory efficiency of ovaries treated with hCG. No significant difference in the percentage of ovulated ova or follicular oocytes demonstrating germinal vesicle breakdown was seen with R2323 treatment. R2323 increased the degeneration rate of ovulated ova in a dose-dependent fashion. In the second experiment, in which experimental ovaries were perfused with R2323 (10(4) ng/ml) plus progesterone (10(3) ng/ml) and the control ovaries with R2323 (10(4) ng/ml) alone ovulation occurred in response to hCG. However, the addition of progesterone to the perfusate reduced the degeneration-inducing effect of R2323 on both ovulated ova and follicular oocytes. In conclusion, R2323 appears to act as an antiprogesterone, thereby promoting the degeneration of oocytes. The increased production of progesterone in the preovulatory follicle following the gonadotropin surge protects oocytes from premature degeneration within the follicles.

Ovarian cells of pregnant rats were cultured with synthetic progestins (R5020, R2323), dexamethasone and RU486. Progesterone and 20 alpha-hydroxy-pregn-4-en-3-one (20 alpha-dihydroprogesterone) in the medium were measured by specific radioimmunoassay. Both R5020 and R2323 increased concentrations of these intrinsic progestins. RU486 decreased concentrations of progesterone, however, the addition of R5020 or R2323 counteracted this action. Immature hypophysectomized rats treated with pregnant mare serum gonadotropin (PMS) and human chorionic gonadotropin (hCG) were administered with RU486; the serum levels of progesterone and 20 alpha-dihydroprogesterone tended to decrease. R5020 and R2323 inhibited the effect of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), whereas RU486 did not. Inhibition of the cholesterol side chain cleavage enzyme (CSCC) by RU486 was more marked than that by R5020 or R2323. These results show that RU486 decreases progesterone synthesis in cultured ovarian cells. A part of the mechanism may involve an inhibition of CSCC.

Danazol and gestrinone are both effective agents in the treatment of endometriosis. Their mechanism of action is unknown but may be related to their androgenic activity, which is at least partly dependent on increases in the proportion of testosterone which circulates unbound to plasma protein. We have quantified these increases in patients on treatment, and by experimentation in vitro have demonstrated the relative importance of the reduction of sex hormone binding globulin (SHBG) binding capacity and competition with testosterone for SHBG binding sites by the drugs and some of their metabolites. The mean SHBG binding capacity in patients treated with danazol (400 mg/d, n = 7) and gestrinone (5 mg/week, n = 7) fell from 66.9 and 56.4 nmol/l to 36.1 and 28.1 nmol/l, after 1 week's treatment and to 11.1 and 7.1 nmol/l after 4 weeks respectively. Despite the similarity between the falls in SHBG binding capacity there was a significantly greater increase in % free testosterone in plasma samples from patients treated with danazol than in those from patients treated with gestrinone at 1 week. Experiments in vitro suggest that this was largely due to ethisterone (a major metabolite of danazol) competing with testosterone for SHBG binding sites. After 4 weeks on treatment there was a similar, near maximal reduction in SHBG binding of testosterone in both treatment groups. At the low levels of SHBG binding capacity reached by this time the extra effect of any competition for binding sites was much reduced.

Danazol and gestrinone are effective drugs in the treatment of endometriosis. Their mechanism of action remains uncertain, but may be related to their androgenic activity. The authors examined the effect of danazol on human endometrial cells cultured in vitro, its two major metabolites, ethisterone and 2 hydroxymethyl ethisterone, gestrinone, and testosterone (T) at 1X and 10X expected plasma concentrations. Danazol and T suppressed growth by 20.8 and 25.0% (P less than 0.01), respectively, at the lower dose, and by 26.9 and 35.5% (P less than 0.01), respectively, at the 10-fold higher dose. No significant suppression of growth occurred with gestrinone, ethisterone, or 2 hydroxymethyl ethisterone. The results provide further evidence that danazol and T (but not gestrinone) may act by a direct effect on endometrial tissue.

Gestrinone (R 2323) is a synthetic progestogen, and noteworthy agent for endometriosis treatment. The effect of this reagent on cultured cells from porcine granulosa, human endometrial and endometrial carcinoma origin was investigated concerning their hormonal activities and cell proliferations. Also, the effect of gestrinone on the serum levels of gonadotropins and gonadal steroids in patients with XY gonadal dysgenesis (Swyer's syndrome) and uterine myoma was studied. The monolayer cell colony established from the endometrial tissue fragments was positively stained by PAS similar to the secretory phase endometrium by 10 ng/ml gestrinone in the culture media. Endometrial carcinoma cells from a 65-year-old patient were proliferated by gestrinone at the concentration of 50 ng/ml in the culture media. The effect of gestrinone on the secretions of progesterone and estradiol-17 beta with or without hCG/testosterone from the cultured porcine granulosa cells was also investigated. Progesterone secretions were stimulated at the 50 ng/ml concentration of gestrinone, especially in association with hCG. Nonetheless, at the concentration of 500 ng/ml, those were inhibited. The secretions of estradiol-17 beta were stimulated by this reagent both with and without testosterone in dose-dependent manners. The effect of 25 mg gestrinone administration for 3 days on the levels of LH, FSH, progesterone and estradiol-17 beta in a patient with XY gonadal dysgenesis was as follows. Both LH and FSH levels gradually decreased, whereas estradiol-17 beta level was increased. The same dosage of this reagent was administered to a patient with uterine myoma on her menstrual days 7, 8, and 9.(ABSTRACT TRUNCATED AT 250 WORDS)

The antifertility mechanism of a new progestin preparation, ethylnorgestrienone (13 beta-ethyl-17 alpha-ethynyl-17-hydroxy-gona-4,9,11-triene-3-one) (R2323), was evaluated. The compound was administered orally in doses of 5 mg weekly to seven subjects for a total of nine treatment cycles. Each woman served as her own control and was studied during a normal menstrual cycle followed by a cycle in which she received R2323. Serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and progesterone, as well as cervical mucus properties, were studied serially during the control and treatment cycles. Results indicated that all control cycles were ovulatory. Ovulatory gonadotropin patterns were observed in four treated cycles, but preovulatory FSH and LH peaks and progesterone production during the luteal phase were suppressed significantly. Estradiol levels showed an early increase during the follicular phase and a significantly decreased preovulatory peak. Cervical mucus properties were altered and sperm penetration in cervical mucus was inhibited in all treatment cycles. These findings suggest that at least two different factors might be involved in the contraceptive mechanism of R2323: (1) alteration of the ovulatory process and progesterone production, and (2) cervical mucus changes leading to inhibition of sperm migration.

The rate of embryo transport through the mouse oviduct was unaltered by ovariectomy after ovulation, essentially unaltered by administration of progesterone after ovulation but increased by preovulatory administration of progesterone. The antiprogestational steroid RMI 12,936 caused an arrest of embryo movement when given on Day 1, 2 or 3 of pregnancy and similar, though less marked, delay was caused by R2323, another progesterone antagonist. The effects of RMI 12,936 given on Day 1 were reversed by progesterone administration after a latent period of 24-48 h. These results indicate that the egg transport process in the mouse in triggered by progesterone and requires continued progesterone activity for its maintenance.

The effects of androgen and estrogen receptor antagonists on the action of danazol and gestrinone (R2323) were investigated. The tropic effect of danazol and gestrinone on sex accessory tissues of castrated, immature male rats was inhibited by the antiandrogen flutamide, whereas the uterotropic action of these steroids in immature female and adult ovariectomized rats was not inhibited by flutamide. In contrast, the uterotropic effect of danazol was reduced by the antiestrogen, LY156758. The estrogen-sensitive endpoints, vaginal keratinization and uterine progesterone receptor concentration, were enhanced by treatment with a combination of flutamide and either danazol or gestrinone. These data indicate that danazol and gestrinone have estrogenic activity that is masked by the androgenic component of these drugs.

Gestrinone (G) was given to 12 females with endometriosis in weekly doses of 5 or 10mg for 4 to 6 months, and the change in serum lipids and lipoproteins was analysed. G decreased total cholesterol by 20% (p less than 0.05), triglycerides by 36% (p less than 0.05), phospholipids by 28% (p less than 0.01) and lipid peroxides by 34% (p less than 0.05), among which reductions in them were statistically significant when compared with the pretreatment levels. Levels of high density lipoproteins (HDL) also fell: HDL-cholesterol by 41% (p less than 0.01), HDL-triglycerides by 49% (p less than 0.05) and HDL-phospholipids by 38% (p less than 0.01) which were significant. Concurrently apolipoproteins (Apo) and lecithin-cholesterol acyltransferase activity (LCAT) decreased: Apo A-I by 31% (p less than 0.01), Apo A-II by 13% (p less than 0.05) and LCAT by 53% (p less than 0.05), which were significant. In contrast, there were few changes in the levels of low density lipoproteins (LDL) and Apo B. There was also little effect on very low density lipoproteins (VLDL) except VLDL-triglycerides which decreased by 52% (p less than 0.05). Meanwhile free fatty acids increased by 61% (p less than 0.05). Therefore, the atherogenic index defined as the ratio of LDL-cholesterol to HDL-cholesterol rose as much as 92% (p less than 0.01) of the initial value in 24 weeks of medication. When these results were examined with respect to the 5 and 10mg administration group, dose-dependent effects were observed, but these were not marked.(ABSTRACT TRUNCATED AT 250 WORDS)