Norethindrone alters growth, sex differentiation and gene expression in marine medaka (Oryzias melastigma).

Norethindrone (NET) is a widely used synthetic progestin, which appears in water environments and threatens aquatic organisms. In this study, marine medaka (Oryzias melastigma) larvae were exposed to 7.6 and 80.1 ng/L NET for 190 days. The effects of NET on growth, sex differentiation, gonad histology and transcriptional expression profiles of hypothalamic-pituitary-gonadal (HPG) axis-related genes were determined. The results showed that exposure to 80.1 ng/L NET caused an all-male marine medaka population and significantly decreased the growth of males. Exposure to 7.6 ng/L NET increased the ratio of males/females in the marine medaka population, decreased the growth of males and delayed the ovary maturation in females. However, the sperm maturation was accelerated by 7.6 or 80.1 ng/L NET. In females, the transcription levels of cytochrome P450 aromatase (cyp19a1a) and progesterone receptor (pgr) in ovaries, glucocorticoid receptor (gr) and vitellogenin (vtg) in livers were suppressed after exposure to 7.6 ng/L NET, which may cause delayed ovary maturation. In males, NET significantly decreased the transcription levels of follicle stimulating hormone ß (fshß) and Luteinizing hormone ß (lhß)in the brain, Estrogen receptor ß (erß)，gr and pgr in the liver, and vitellogenin receptor (vtgr) in the testes, while NET of 80.1 ng/L led to a significant up-regulation of steroidogenic acute regulatory protein (star) in the testes of males. These results showed that NET could influence growth, sex differentiation and gonadal maturation and significantly alter the transcriptional expression levels of HPG axis-related genes.

A new progestin from fungal transformation of norethisterone and its comparative antimicrobial studies.

Fungal transformation of a norethisterone (17α-ethynylestra-4-en-17ß-ol-3-one) (1) by using Macrophomina phaseolina and Paecilomyces variotii was studied. A new metabolite, 17α-hydroxymethyl-androst-4-en-11ß-ol-3-one-17ß-acetate (2) with novel changes and a known metabolite, 17α-ethynylestradiol (3) were obtained from 1 by using M. phaseolina and P. variotii, respectively. Based on various spectroscopic techniques, the structures of both metabolites were characterized. The antimicrobial activities of 1-3 were also evaluated. Compound 1 was found to be moderately active against Salmonella paratyphi while 1-3 were almost inactive against other microorganisms.

Neurodevelopmental effects of natural and synthetic ligands of estrogen and progesterone receptors in zebrafish eleutheroembryos.

Natural and synthetic estrogens and progestins are widely used in human and veterinary medicine and are detected in waste and surface waters. Our previous studies have clearly shown that a number of these substances targets the brain to induce the estrogen-regulated brain aromatase expression but the consequences on brain development remain virtually unexplored. The aim of the present study was therefore to investigate the effect of estradiol (E2), progesterone (P4) and norethindrone (NOR), a 19-nortestosterone progestin, on zebrafish larval neurogenesis. We first demonstrated using real-time quantitative PCR that nuclear estrogen and progesterone receptor brain expression is impacted by E2, P4 and NOR. We brought evidence that brain proliferative and apoptotic activities were differentially affected depending on the steroidal hormone studied, the concentration of steroids and the region investigated. Our findings demonstrate for the first time that steroid compounds released in aquatic environment have the capacity to disrupt key cellular events involved in brain development in zebrafish embryos further questioning the short- and long-term consequences of this disruption on the physiology and behavior of organisms.

PGRMC1 in animal breast cancer tissue and blood is associated with increased tumor growth with norethisterone in contrast to progesterone and dydrogesterone: four-arm randomized placebo-controlled xenograft study.

Progesterone receptor membrane component 1 (PGRMC1) is mediating strong breast cancer cell proliferation induced by certain synthetic progestogens which we have shown within already published in vitro studies. Aim was now to use an animal model, to compare tumor growth using progesterone and its isomer dydrogesterone with norethisterone, which elicited in our in vitro studies the strongest proliferating effect. For the first time, we wanted to investigate if growth can be correlated both with blood concentrations and tissue expression of PGRMC1 to identify if PGRMC1 could be a new tumor marker. Prospective, randomized, blinded, placebo-controlled four-arm study (45-50 days); PGRMC1-transfected or empty-vector T47D- and MCF7-xenotransplants were each treated with estradiol (E2) +placebo; E2 + progesterone; E2 + norethisterone; E2 + dydrogesterone; blood PGRMC1 assessed by a novel ELISA, tissue expression by immunohistochemistry. PGRMC1-transfected tumors further increased with E2 + norethisterone but not with E2-dydrogesterone or E2-progesterone. In both PGRMC1-xenograft groups (T47D, MCF7) with E2/norethisterone, the blood concentrations and tissue expression of PGRMC1 were higher than in all other 14 groups (p < .05), with positive significant correlation between blood PGRMCI concentrations and tissue PGRMC1 expression. In the presence of PGRMC1, certain progestogens could increase the growth of breast tumor, which now also should be tested in clinical studies.

Successful management of abnormal uterine bleeding from uterine arteriovenous malformations with progesterone in postabortal patients.

AIM: To study the feasibility of conservative management with progesterone as a treatment option for postabortal patients with uterine arterio-venous malformations (AVMs). METHODS: This prospective observational study was conducted in the tertiary care teaching hospital over a period of 2 years. Postabortal patients with abnormal uterine bleeding were enrolled. Diagnosis was made by history, clinical and radiological examinations. Oral norethisterone was used (10 mg twice daily for 3 weeks, maximum of three cycles). Descriptive statistics was used to present the data. RESULTS: A total of 30 patients were included. Majority (n = 17) had complete resolution of symptoms after a single 3-week course of progesterone therapy. Rest (n = 13) remained symptomatic and required second course. Of the later, only three remained symptomatic after 2 months, and underwent CT angiography followed by embolization. There was no report of any serious adverse events. CONCLUSION: Oral norethisterone is a safe, effective and novel oral drug as an alternative to embolization or surgical therapy for patients with postabortal AVM bleed. Larger studies are required to confirm the findings of the present study.

Comparing cervical mucus changes in response to an oral progestin or oestrogen withdrawal in ovarian-suppressed women: a clinical pilot.

Purpose: Prior studies evaluating the effect of administered progestogens on peak cervical mucus have not controlled for the influence of endogenous hormones. To address this, we treated women with a gonadotropin-releasing hormone (GnRH) agonist to suppress the hypothalamus-pituitary-ovarian (HPO) axis and used transdermal oestradiol replacement to stimulate peak cervical mucus and then evaluated the effects of an oral progestin or oestradiol withdrawal. Materials and methods: We used a crossover design to examine cervical mucus changes in women receiving transdermal oestradiol replacement following intramuscular administration of leuprolide acetate. After increasing oestradiol patches to mid-cycle levels, subjects were assigned to either 0.35 mg oral norethindrone with continuation of the patches (NET) or oestradiol withdrawal by patch removal (E2WD). We collected serum and cervical mucus samples at 0, 2, 4, 6, 22 and 24 h following the intervention. Results: We analysed 12 cycles (6 NET, 6 E2WD) from three subjects. Baseline cervical mucus scores were favourable to sperm penetration [NET median 11, interquartile range (9-12), E2WD 13 (12-13)]. Two hours after removal of oestradiol patch or administration of norethindrone, cervical mucus scores declined [NET 8.5 (4-9), E2WD 10.5 (10-12)]. Low cervical mucus scores persisted at 24 h with NET [8.0 (7-8)] but not E2WD [10.5 (8-11)]. Conclusions: We observed a rapid decline in cervical mucus Insler scores following administration of a single dose of oral norethindrone, and scores remained lower and unfavourable through 24 h. Oestradiol withdrawal did not result in similar unfavourable changes.

The association between progestins, nuclear receptors expression and inflammation in endometrial stromal cells from women with endometriosis.

Endometriosis is an inflammatory disease and nuclear receptors play a crucial role in mediating the inflammatory response. In endometrial stromal cells (ESC), nuclear receptors expression can be influenced by the local environment. Progestins are first-line, on-label treatments of endometriosis that may have direct effects on endometriotic lesions through these nuclear receptors. Therefore, we investigated whether there was an association between nuclear receptors expression and the influence of progestins on inflammatory cytokines production in a preliminary, in vitro study with primary cultures. ESC from endometrial biopsies of six subjects with histologically confirmed endometriosis were treated for 6 h with medium alone or with TNF-α (10 or 100 ng/ml) in the presence of dienogest (DNG), medroxyprogesterone acetate (MPA) and norethisterone acetate (NETA) 10-5 M. The progestin-mediated change in IL6, IL8 and MCP-1 mRNA transcription was measured, as was the PRA, PRB, GR, AR and MCR protein expression. The change (medium versus TNF-α 10 ng/ml and medium versus TNF-α 100 ng/ml) in IL6 mRNA transcription was positively associated with the change in PRB, but not PRA with both DNG and NETA treatment. The change in IL8 mRNA was negatively associated with AR expression in the presence of NETA. The change in MCP-1 mRNA expression was positively associated with GR expression and negatively associated with MCR after MPA treatment. The associations between the change in cytokines mRNA expression and nuclear receptors protein expression in response to progestins activity may indirectly suggest different activities of these compounds at a local level worthy of further investigations.

Does menopausal hormone therapy (MHT), exercise or a combination of both, improve pain and function in post-menopausal women with greater trochanteric pain syndrome (GTPS)? A randomised controlled trial.

BACKGROUND: Greater trochanteric pain syndrome (GTPS) is pathology in the gluteus medius and minimus tendons and trochanteric bursa that causes debilitating tendon pain and dysfunction, particularly in post-menopausal women. Limited evidence in clinical studies suggests hormone changes after menopause may have a negative effect on tendon. This protocol describes a randomised controlled trial comparing the effectiveness of menopausal hormone therapy (MHT) and exercise therapy in reducing pain and dysfunction associated with GTPS in post-menopausal women. METHOD: One hundred and sixteen post-menopausal women will be recruited and randomised to receive one of two exercise programs (sham or targeted intervention exercise) and transdermal creams (MHT cream containing oestradiol 50mcg and norethisterone acetate 140mcg or placebo cream). Interventions will be 12-weeks in duration and outcomes will be examined at baseline, 12-weeks and 52-weeks. The primary outcome measure will be the VISA-G questionnaire and secondary outcomes measures will include three hip pain and function questionnaires (Hip dysfunction and Osteoarthritis Outcome Score, Oxford Hip Score, Lateral Hip Pain questionnaire), a global change in symptom questionnaire (using a 15-point Likert scale) and a quality of life measure (AQoL-8D questionnaire). Data will be analysed using the intention to treat principle. DISCUSSION: This study is the first randomised controlled trial to compare the effectiveness of menopausal hormone therapy therapy alone, and with the combination of exercise therapy, to treat pain and dysfunction associated with GTPS. This study has been pragmatically designed to ensure that the interventions in this study can be integrated into policy and clinical practice if found to be effective in the treatment of GTPS in post-menopausal women. If successful, there is potential for this treatment regimen to be explored in future studies of other persistent tendon conditions in the post-menopausal population. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12614001157662 Registered 31 October 2014.

A survey of bonobo (Pan paniscus) oral contraceptive pill use in North American zoos.

Contraception is an essential tool in reproductive management of captive species. The Association of Zoos and Aquariums (AZA) Reproductive Management Center (RMC) gathers data on contraception use and provides recommendations. Although apes have been given oral contraceptive pills (OCPs) for at least 30 years, there have been no published reports with basic information on why the pill is administered, formulations and brands used, and effects on physiology and behavior. Here, we report survey results characterizing OCP use in bonobos (Pan paniscus) housed in North American zoos, as well as information accumulated in the RMC's Contraception Database. Of 26 females treated, there have been no failures and nine reversals. The most commonly administered OCP formulation in bonobos contained ethinyl estradiol (EE) 35 µg/norethindrone 1 mg. Few females on combined oral contraceptives (COCs) were given a continuous active pill regimen; a hormone-free interval of at least 5 days was allowed in most. Crushing the pill and mixing with juice or food was common. Females on COCs seldom experienced breakthrough estrus or bleeding, while these conditions were sometimes observed for females on continuous COCs. All females on COCs exhibited some degree of perineal swelling, with a mean score of 3 or 3+ most commonly reported. Behavioral changes included less sexual behavior, dominant females becoming subordinate, and a negative effect on mood. No appreciable change in weight was noted. Taken together, these results indicate that OCPs are an effective and reversible contraceptive option for bonobos that can be used by zoos and sanctuaries to limit reproduction. Zoo Biol. 35:444-453, 2016. © Wiley Periodicals, Inc.

Effects of estradiol, progestogens, and of tibolone on breast proliferation and apoptosis.

AIM: To study the effects of estrogen therapy, alone or combined with progestogens, and of tibolone on the expression of proliferation and apoptosis markers in normal breast tissue. METHODS: Thirty 250-day-old Wistar rats were castrated and 3 weeks later received one of the following treatments by gavage for 5 weeks: (1) estradiol benzoate; (2) estradiol benzoate + medroxyprogesterone acetate; (3) estradiol benzoate + norethisterone acetate; (4) estradiol benzoate + dydrogesterone; (5) tibolone; (6) placebo. Following treatment, the expression of proliferating cell nuclear antigen (PCNA) and caspase-3 was analyzed by quantitative immunohistochemistry in the breast tissue, and proliferation and apoptosis were analyzed semiquantitatively by microscopic imaging. RESULTS: There was a statistically significant difference among the groups for PCNA, caspase-3 and the caspase-3 : PCNA ratio. Tibolone was associated with the lowest proliferative activity, followed by estradiol benzoate + dydrogesterone; however, estradiol benzoate + dydrogesterone showed the greatest rate of apoptosis. CONCLUSIONS: The various progestogens can have more or less proliferative and pro-apoptotic effects than estradiol alone. Among the treatment schemes analyzed, the estradiol + dydrogesterone combination resulted in a higher apoptosis rate in relation to the proliferation rate and tibolone was associated with the lowest proliferation.

Is expression of rat breast matrix components influenced by estrogen, progestins and tibolone?

AIM: To study the effects of estrogen therapy, alone or combined with progestogens, and of tibolone on the expression of heparanase (HSPE), extracellular matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9), perlecan and proliferating cell nuclear antigen (PCNA) in normal breast tissue. METHODS: Thirty 250-day-old Wistar rats were castrated and 3 weeks later received one of the following treatments by gavage for 5 weeks: (1) estradiol benzoate; (2) estradiol benzoate + medroxyprogesterone acetate; (3) estradiol benzoate + norethisterone acetate; (4) estradiol benzoate + dydrogesterone; (5) tibolone; (6) placebo. Following treatment, the expressions of mRNA for HSPE, MMP-2 and MMP-9 were analyzed by real-time PCR and the protein expressions of HSPE, MMP-2, MMP-9, perlecan and PCNA were quantified by immunohistochemistry. RESULTS: There was a statistically significant difference among the groups for the expression of HSPE mRNA due to high levels in the tibolone group. The groups differed in terms of PCNA, with lower levels found in the tibolone group followed by the estradiol benzoate + dydrogesterone group. A statistically significant positive correlation was observed for PCNA versus perlecan and MMP-9. CONCLUSIONS: There was no difference in the effects of combinations of estradiol and different progestogens on extracellular matrix components, and breast cell proliferation was associated with increases in perlecan and MMP-9.

Estrone - a partial estradiol antagonist in the normal breast.

Oral hormone replacement therapy (HRT) based on estradiol-17ß (E2) greatly increases circulating estrone (E1) levels. E1 is an estrogen receptor agonist but may also be a partial E2 antagonist. We investigated the effects of circulating E1 on the association between circulating E2 and the increase in mammographic density (∂MD) in 46 healthy post-menopausal women treated with E2 2 mg and norethisterone acetate 1 mg daily. MD and serum E1 and E2 were measured before and after 6 months of treatment. At high E1 levels, ∂MD showed significant positive correlations leading to increase (∂-values) in both E1 and E2. Lowering the upper serum E1 limit strengthened the correlations to ∂E2 while the significant correlations to ∂E1 disappeared. E1 at high concentrations may act as a partial E2 antagonist also in the normal breast in vivo and disturb relationships between circulating E2 and biological estrogen effects. When investigating the relations between circulating steroids and their effects, structurally related compounds, which may act as partial antagonists, have to be considered, at least when they are present in higher concentrations.

The effect of protease inhibitors on the cervical mucus of HIV-positive women taking norethindrone contraception.

OBJECTIVE: To compare cervical mucus score (CMS) with and without protease inhibitors (PI) before and after taking norethindrone (NET). STUDY DESIGN: This two-arm, researcher blinded, non-randomised, prospective study was conducted to evaluate cervical mucus quality in HIV-positive women taking progestin only pills. The study group was taking a PI, and compared to women taking ARV regimens that have demonstrated no significant interaction with NET in prior pharmacokinetic trials with combined oral contraceptives. The women had a cervical mucus score prior to NET administration. Mucus Scoring was repeated after 21 days of steady state exposure to oral NET 0.35 milligrams. Cervical mucus quality was quantified according to the World Health Organisation criteria, which include: volume, consistency, cellularity, spinnbarkeit, and ferning. RESULTS: Sixteen women took PI and 17 were controls. Baseline CMS were similar (p ≥ 0.1). After 21 days CMS were similar among the two groups (p = 1). CONCLUSIONS: HIV-positive women taking PI demonstrated thickened cervical mucus with oral norethindrone 0.35 mg and are similar to HIV-positive women taking no PI therapy. This may suggest no difference in contraceptive efficacy of progestin only pills in HIV-positive women taking PI.

Pharmacokinetic and pharmacodynamic interactions between the hepatitis C virus protease inhibitor, boceprevir, and the oral contraceptive ethinyl estradiol/norethindrone.

PURPOSE: The purpose of this study was to examine drug interactions between boceprevir, a hepatitis C virus NS3/4A protease inhibitor, and a combined oral contraceptive containing ethinyl estradiol (EE) and norethindrone (NE). METHODS: A single-center, open-label study was conducted in 20 healthy female volunteers. In three consecutive 28-day treatment periods, subjects received EE/NE (0.035 mg/1 mg; 21 days on, 7 days off). During period 3, subjects also received boceprevir (800 mg three times daily) for 28 days. RESULTS: Coadministration of boceprevir with EE/NE did not affect NE AUC0-24 but slightly reduced NE C max. Geometric mean ratios (GMRs) for NE AUC0-24 and C max with EE/NE alone and EE/NE plus boceprevir were 0.96 (90% confidence interval (CI), 0.87-1.06) and 0.83 (90% CI, 0.76-0.90). Coadministration of boceprevir with EE/NE reduced EE AUC0-24 and C max by 26 and 21%, with GMRs of 0.74 (90% CI, 0.68-0.80) and 0.79 (90% CI, 0.75-0.84). Boceprevir had no effect on mid-cycle luteinizing hormone (LH), follicle-stimulating hormone (FSH), or sex hormone-binding globulin levels, and progesterone concentrations remained <1 ng/ml during the luteal phase. Adverse events reported in this study were consistent with the well-established safety profile of boceprevir. CONCLUSION: Serum progesterone, LH, and FSH levels indicate that ovulation was suppressed during coadministration of boceprevir with EE/NE. Coadministration of boceprevir with combined oral contraceptives containing EE and ≥1 mg of NE is therefore unlikely to alter contraceptive effectiveness. The ovulation suppression activity of oral contraceptives containing lower doses of NE, and of other forms of hormonal contraception during coadministration with boceprevir, has not been established.

The effect of hormone therapy on biochemical and ultrasound parameters associated with atherosclerosis in 46,XY DSD individuals with female phenotype.

The aim of this study was to evaluate the effect of hormone therapy (HT) in the endothelial function of 46,XY disorders of sexual development (DSD) patients with female phenotype. Biochemical and ultrasound measurements were performed in 20 patients at initiation of oral 2 mg 17ß-estradiol/1 mg norethisterone acetate, and after 6 months of therapy. Lipid profile, including total cholesterol (TC), LDL, HDL, triglycerides (TG) and Atherogenic Index of Plasma (AIP), as well as levels of VE-Cadherin, E-Selectin, Thrombomodulin and vWf were determined. Ultrasonographic examinations included evaluation of flow-mediated dilatation (FMD) and measurement of Carotid and Femoral Intima Media Thickness (IMT). HT raised HDL (35.4 mg/dl versus 40.1 mg/dl, p = 0.019) while lowering TG (166 mg/dl versus 109 mg/dl, p = 0.026) and AIP (0.24 versus 0.04, p = 0.007). No changes were noted in TC and LDL (215.7 mg/dl versus 192.25 mg/dl and 87.46 mg/dl versus 76.35 mg/dl, respectively). There was significant reduction of VE-Cadherin (4.05 ng/ml versus 2.20 ng/ml, p = 0.002) and E-selectin (73.98 ng/ml versus 56.73 ng/ml, p = 0.004). No change was observed in Thrombomodulin and vWf (11.76 ng/ml versus 13.90 ng/ml and 80.75% versus 79.55%, respectively). FMD improved significantly (5.4% versus 8.15%, p = 0.003), while only carotid bulb IMT decreased significantly (0.65 mm versus 0.60 mm, p = 0.018). Overall, HT was found to improve biochemical and ultrasound markers of endothelial function in 46,XY DSD patients with female phenotype.

Norethindrone-induced masculinization and progeny testing in guppy, Poecilia reticulata (Peters 1859).

Norethindrone(NE) was evaluated for its efficacy on alteration of sex ratio of P. reticulata. Either the young fry or the brooders and the resultant fry were fed a commercial diet incorporated with NE at 0, 25, 50, 75 and 100 mg kg(-1) diet (ppm) for 30-40 d in rectangular glass aquaria; this was followed by 40-60 d rearing on NE-free diet in out-door concrete tanks. In general, the androgen treatment altered sex ratio, leading to the production of a dose dependent increase in the percentage of males. The oral administration of the steroid at 75 ppm for 40 d or 100 ppmfor 30 or 40 d to first feeding fry, yielded 100% males. On the other hand, NE administration to brooders before parturition and the resultant fry also produced an all-male population of guppy. The sex ratio of the untreated control was almost 1:1. The survival of fish in all the trials was high, ranging between 67 and 100%. Mating masculinized males ("XX" male) with normal female resulted in an all-female progeny, while crossing normal male (XY) from treatment groups with normal female sired normal sex ratio (1:1), elucidating XX-XY sex determination system in the guppy.

Relugolix/Estradiol/Norethisterone Acetate: A Review in Endometriosis-Associated Pain.

An oral fixed-dose combination of relugolix/estradiol/norethisterone (also known as norethindrone) acetate [Myfembree® (USA); Ryeqo® (EU)] (hereafter referred to as relugolix combination therapy) has been approved in the USA for the management of moderate to severe pain associated with endometriosis in premenopausal women and in the EU for the symptomatic treatment of endometriosis in adult women of reproductive age with a history of previous medical or surgical treatment for their endometriosis. The gonadotropin-releasing hormone (GnRH) receptor antagonist relugolix decreases estradiol and progesterone levels, while the addition of estradiol/norethisterone acetate mitigates hypoestrogenic effects including bone mineral density (BMD) loss and vasomotor symptoms. In two pivotal phase III trials, relugolix combination therapy significantly improved dysmenorrhoea and non-menstrual pelvic pain in premenopausal women with moderate to severe endometriosis. The combination also reduced overall pelvic pain and dyspareunia, reduced analgesic and opioid use, and improved health-related quality of life. The efficacy of relugolix combination therapy was sustained over the longer term (up to 2 years). Relugolix combination therapy was generally well tolerated and BMD loss over time was minimal. With the convenience of a once daily oral dosing regimen, relugolix combination therapy is a valuable addition to the options currently available for the management of endometriosis-associated pain.

Endometriosis is a disease where tissue similar to the lining of the uterus grows outside the uterus and may reach other organs. This causes chronic pain as a result of increased inflammation and scar tissue. Women with endometriosis may experience painful menstrual periods, pelvic pain between periods, pain during sex, painful bowel movements and painful urination. Recently, a fixed-dose tablet comprising relugolix, estradiol and norethisterone (also known as norethindrone) acetate [Myfembree^® (USA); Ryeqo^® (EU)] (hereafter referred to as relugolix combination therapy) has been approved to treat endometriosis-associated pain. The treatment works by decreasing levels of ovarian hormones (estrogen and progesterone). In clinical trials, relugolix combination therapy improved period pain and pain between periods in women with moderate to severe pain associated with endometriosis. The treatment also improved other symptoms (overall pelvic pain and pain during sex), reduced the need for pain medications and improved health-related quality of life. Relugolix combination therapy was generally well tolerated and caused minimal bone loss, which is known to occur with some hormone therapies. With the convenience of a once daily oral pill, relugolix combination therapy is a valuable addition to the options currently available for women with endometriosis-associated pain.

Investigating the anti-mineralocorticoid properties of synthetic progestins used in hormone therapy.

A more detailed understanding of the affinities and efficacies for transcriptional regulation by the synthetic progestins medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-A) via the mineralocorticoid receptor (MR) is required, to better understand their relative risk profiles. Both MPA and NET-A bind to the MR, although with about 100-fold lower affinities than that of Prog. MPA and NET-A exhibit no agonist activity, but NET-A, unlike MPA, has similar antagonistic efficacy to Prog on the endogenous mineralocorticoid/glucocorticoid response element (MRE/GRE)-containing genes, α-glycolytic protein or orosomucoid-1 (Orm-1) and plasminogen activator inhibitor-1 (PAI-1). This study is the first to show that NET-A, but not MPA, can dissociate between transrepression and transactivation via the MR. Given the relatively low affinity and potency of MPA and NET-A for the MR, our results suggest that these progestins are unlikeley to exert significant effects via the MR at doses used in hormonal therapy. However, considering their relative free concentrations compared to endogenous hormones, the possibility that NET-A may exhibit significant MR antagonist activity, with some possible cardiovascular protective benefits, should not be excluded.

Effects of tibolone or continuous combined oestradiol/norethisterone acetate on glucose and insulin metabolism.

OBJECTIVE: To determine the effects of tibolone or oestradiol (E(2) )/norethisterone acetate (NETA) hormone replacement therapy on glucose and insulin metabolism in postmenopausal women. DESIGN: Single-centre double-blind placebo-controlled randomized clinical trial. SUBJECTS/METHODS: We randomized 105 healthy postmenopausal women to tibolone 2·5 mg daily, continuous combined oral E(2) 2 mg/NETA 1 mg daily or placebo over a 2-year study. We performed intravenous glucose tolerance tests (IVGTT) with measurements of plasma glucose, insulin and C-peptide concentrations and the IVGTT glucose elimination rate, k. Mathematical modelling was performed to determine measures of insulin sensitivity, S(i) , pancreatic insulin secretion and hepatic and plasma insulin elimination. RESULTS: Tibolone decreased S(i) to 53-63% and k to 72-79% of baseline values but increased IVGTT phase 2 C-peptide concentrations 1·6-1·8-fold and pancreatic insulin secretion 2·2-2·4-fold, so overall IVGTT glucose concentrations were unaffected. Similar, but for k, significantly smaller changes in insulin and C-peptide secretion were seen with E(2) /NETA, also with no effect on overall IVGTT glucose concentrations. CONCLUSIONS: Tibolone reduces insulin sensitivity. Healthy postmenopausal women seem able to compensate for this and maintain normal postload glucose concentrations, but it may not be advisable to prescribe tibolone to women with, or at increased risk for, diabetes.