Nestorone (segesterone acetate) effects on neuroregeneration.

Nestorone® (segesterone acetate) is a progestin with a chemical structure closely related to progesterone with high affinity and selectivity for the progesterone receptor without significant interaction with other steroid receptors. It has been developed for female and male contraception and is FDA-approved in a first long-acting contraceptive vaginal system for female contraception. Its safety has been extensively demonstrated in both preclinical and clinical studies for contraceptive indications. Nestorone was found to display neuroprotective and neuroregenerative activity in animal models of various central nervous system diseases, including multiple sclerosis, stroke, and amyotrophic lateral sclerosis. Reviewed herein are neuroprotective and myelin- regenerating properties of Nestorone in various animal models and its translational potential as a therapeutic agent for debilitating neurological diseases for which limited therapeutic options are available (Table 1).

[Development possibilities of hormone-containing implants for gynecological applications: A review]. / Nogyógyászati célra szánt, hormontartalmú implantátumok fejlesztési lehetoségeinek áttekintése: irodalmi áttekintés.

Implantable gynecological drug delivery devices are applied for contraceptive, hormone replacement purposes and for the treatments of other gynecological diseases, e.g. endometriosis. The review provides a comprehensive overview about the indications, advantages, limitation of application and the applied technologies of hormone-containing implants, as well. The study comprises the relevant patents and the recently published papers.

Membrane progestin receptor alpha mediates progestin-induced sperm hypermotility and increased fertilization success in southern flounder (Paralichthys lethostigma).

Progestin hormones stimulate sperm motility in teleosts but their mechanisms of action remain unclear. Preliminary results suggest that progestin upregulation of sperm motility in southern flounder and several other marine species is mediated through a sperm membrane progestin receptor with the characteristics of membrane progestin receptor alpha (mPRα, also known as Paqr7b). The hypothesis that mPRα has an important role in progestin regulation of southern flounder sperm motility and fertility was tested in the present study. The specific mPRα agonist, 10-ethenyl-19-norprogesterone (Org OD 02-0, 100nM), mimicked the stimulatory actions of the endogenous progestin, 17,20ß, 21-trihydroxy-4-pregnen-3-one (20ß-S, 100nM) on flounder sperm motility. The concentration of the mPRα protein on sperm plasma membranes was positively correlated to sperm motility as well as the responsiveness of sperm to progestin stimulation. Acute in vitro progestin treatment of sperm with high mPRα protein levels increased both sperm motility and fertilization success in strip spawning experiments. However, in vitro progestin treatments were ineffective on sperm with low receptor abundance. A single injection of the superactive gonadotropin-releasing hormone analog (LHRHa, 100µg/kg) increased sperm motility and fertilization success in strip spawning experiments 72h post-injection which was accompanied by an increase in mPRα protein concentrations on sperm plasma membranes. These results provide clear evidence that southern flounder sperm hypermotility is mediated through mPRα. Stimulatory G proteins, but not inhibitory G proteins, were identified in flounder sperm plasma membrane fractions. The finding that treatment of flounder sperm plasma membrane fractions with either 20ß-S or Org OD 02-0 increases cAMP levels suggests progestins stimulate flounder sperm motility by activating an mPRα/stimulatory G protein/membrane adenylyl cyclase pathway. A similar mechanism has been identified in Atlantic croaker, suggesting that the signaling pathway mediated by mPRα in sperm is highly conserved in advanced teleosts. Collectively, our results indicate that progestin-stimulation of flounder sperm hypermotility and fertility is dependent on a sufficient concentration of mPRα which can be upregulated by in vivo LHRHa treatments. These findings potentially have practical applications for enhancing the fertility of male flounder broodstock.

Optimization of the preparation of fluorine-18-labeled steroid receptor ligands 16alpha-[18F]fluoroestradiol (FES), [18F]fluoro furanyl norprogesterone (FFNP), and 16beta-[18F]fluoro-5alpha-dihydrotestosterone (FDHT) as radiopharmaceuticals.

Fluorine-18-labeled steroid receptor tracers, 16α-[(18)F]fluoroestradiol (FES), [(18)F]fluoro furanyl norprogesterone (FFNP), and 16ß-[(18)F]fluoro-5α-dihydrotestosterone (FDHT), are important imaging tools for studies of breast and prostate cancers using positron emission tomography (PET). The automated production of these ligands with high specific activity (SA) as radiopharmaceuticals requires modification and optimization of the currently reported methods. [(18)F]FES with high SA was synthesized in over 60% radiochemical yield (RCY) at the end of synthesis (EOS) using a small amount of precursor (1) (as low as 0.3 mg) and 1 M H2SO4 for deprotection of the intermediate (2). [(18)F]FFNP was synthesized in up to 77% RCY at EOS using the triflate precursor (4) at room temperature or in 25% RCY using the mesylate precursor (6) at 65°C. Both methods are highly reproducible and afford high SA. [(18)F]FDHT was synthesized by radiofluoride incorporation at room temperature, reduction with NaBH4 , and deprotection with HCl/acetone, giving [(18)F]FDHT in up to 75% yield (RCY). All of these methods can be easily translated to automated production. The information provided here will aid in the development of automated production of these steroid receptor tracers with high or improved yields, optimal SA, and ease of processing for research and clinical use.

Progesterone and related progestins: potential new health benefits.

Progesterone is a steroid hormone that is essential for the regulation of reproductive function. The main physiological roles of this hormone have been widely described. Progesterone and progestins have been approved for a number of indications including the treatment of irregular and anovulatory menstrual cycles and, when combined with estrogen, for contraception, and the prevention of endometrial hyperplasia in postmenopausal hormonal replacement therapy (HRT) regimens. Lack of understanding between the differences in categories of the progestins as well as with the physiological hormone has resulted in considerable controversy surrounding the use of progestins for HRT regimens. Newer evidence suggests that there are distinct differences between the molecules and there is no progestin class effect, with regard to benefits or side-effects. In addition to its role in reproduction, progesterone regulates a number of biologically distinct processes in other tissues, particularly in the nervous system and the vessels. Recently, it has been shown in animal experiments that progesterone and the progestin Nestorone(®) have positive effects on neuroregeneration and repair of brain damage, as well as myelin repair. The potential benefits of natural progesterone and its related derivatives warrant further investigation. It is hoped that a better understanding of the mechanism of action of progesterone and selected progestins will help in defining better therapies for men and women.

Nestorone nanosuspension-loaded dissolving microneedles array patch: A promising novel approach for "on-demand" hormonal female-controlled peritcoital contraception.

"On demand" hormonal female-controlled pericoital contraception is one strategy which could be used to minimize the impact of unintended pregnancy. Nestorone (NES) is a potent contraceptive, with relatively few side effects in comparison with other contraceptives. NES presents an attractive option for "on demand" pericoital contraceptive. Unfortunately, the drug is inactive if taken orally, but it has high progestational activity and antiovulatory potency if administered parenterally. Current drug delivery systems, such as a transdermal hydrogel are not so satisfactory. Dissolving microneedles array (DMNs) are an attractive alternative, minimally-invasive, delivery system. In this study, we report, for the first time, development of tip-loaded NES-nanosuspension (NES-NS)-loaded bilayer DMNs to deliver NES intradermally for subsequent release. NES-NS was prepared and optimised, freeze-dried and then used to fabricate DMNs using a blend of two biocompatible polymers, namely poly(vinyl alcohol) and poly(vinyl pyrrolidone). Both NES-NS and the NES-NS-loaded DMNs were fully characterised and the performance of the DMNs was evaluated in vivo using Sprague Dawley rats. Results showed that the finalised NES-NS had particle size and PDI values of 666.06 ± 1.86 nm and 0.183 ± 0.01, respectively. The NES-NS-DMNs had relatively high tips-localised drug loading (approximately 2.26 ± 1.98 mg/array) and exhibited satisfactory mechanical and insertion properties. In Sprague Dawley rats, DMNs delivered NES into the skin, with the drug then appearing in blood and rapidly reaching its maximum concentration (Cmax of 32.68 ± 14.06 ng/mL) within 1 h post-DMNs application. Plasma levels above 3.4 ng/mL were maintained for 2 days. This suggests that DMNs are a promising drug delivery system that could be used to deliver NES as an "On demand" hormonal female-controlled pericoital contraceptive.

The use of serum segesterone acetate levels to assess adherence of trial participants with a contraceptive vaginal ring.

OBJECTIVES: To determine the incidence of out-of-range segesterone acetate (NES) concentrations in participants of a pharmacokinetic/pharmacodynamic trial of a continuous use contraceptive vaginal ring (CVR) releasing NES and estradiol (E2). We hypothesized that out-of-range concentrations reflect nonadherent ring use and predict ovulation risk. STUDY DESIGN: We conducted a secondary analysis of data from a prospective, multi-centered, randomized, Phase IIa dose-finding trial for a CVR releasing NES and E2. Our primary outcome was the risk of ovulation associated with out-of-range NES events. We calculated the 5th and 95th percentile NES concentrations of subjects at steady state to determine high and low cutoffs. We used a Fisher's exact test to determine group differences, and calculated the relative risk of ovulation for each group. RESULTS: We analyzed available serum NES data from cycles 2 (n = 172), 3 (n = 156) and 7 (n = 115) to determine the 5th and 95th percentile of all NES concentrations (64, 296 pg/mL). In the 443 cycles of observation, no ovulations occurred in participants with NES concentrations within the expected range. In contrast, we found ovulatory elevations of progesterone in 21 cycles with out-of-range values. Of these, 15 (71%) cycles had evidence of one or more nonadherent low and 6 (29%) one or more unexpected peak. The relative risk of ovulation increased with evidence of multiple non-adherent levels. CONCLUSIONS: We found out-of-range NES concentrations, suggestive of improper use of a CVR associated with an increased risk of ovulation, with a direct relationship between the number of out-of-range events and the relative risk. IMPLICATIONS: The results of this study support the use of out-of-range serum NES values as a marker of adherence in contraceptive clinical trials of continuous vaginal rings, and suggest that nonadherence occurs even in early phase clinical trials with close monitoring.

Contraceptive drug, Nestorone, enhances stem cell-mediated remodeling of the stroke brain by dampening inflammation and rescuing mitochondria.

Ischemic stroke remains a significant unmet need causing massive mortality and morbidity due to few treatment options with limited therapeutic window. The progestin Nestorone® (segesterone acetate) displays high affinity for the progesterone receptor in exerting its potent birth control and hormone replacement therapy. Accumulating evidence implicates a new utility of Nestorone in affording neuroprotection in a variety of central nervous system diseases, including stroke. However, the mechanism of action mediating Nestorone's neuroprotection in stroke remains unknown. Here, we showed that stand-alone treatments of Nestorone or human amniotic fluid-derived stem cells (hAFSc), but more pronounced with their combined treatment, led to significant improvements in behavioral function and reductions in infarction and peri-infarct cell loss in adult rats with ischemic stroke. We detected significantly lower levels of pro-inflammatory signals (OX6 and IBA1) coupled with enhanced levels of stem cell proliferation (Ki67) and differentiation (DCX and MAP2) in both brain and spleen of stroke rats that received stand-alone or combined treatments of Nestorone and hAFSc. In concert, the in vitro oxygen-glucose deprivation stroke model revealed that neural stem cells treated with Nestorone exhibited increased stem cell proliferation and differentiation that was accompanied by rescue of the mitochondrial respiratory activity characterized by reduced mitochondrial reactive oxygen species, increased ATP, elevated mitochondrial deacetylase Sirtuin 3 (SIRT3), and a normalized ratio of acetyl-superoxide dismutase 2 (Ac-SOD2)/SOD2, suggesting the key role of mitochondrial metabolism and oxidative protection in Nestorone's therapeutic effects in stroke.

Sex differences in the cerebroprotection by Nestorone intranasal delivery following stroke in mice.

Our previous studies showed that intranasal delivery of progesterone offers a good bioavailability and neuroprotective efficacy after experimental stroke. We have also demonstrated that progesterone receptors (PR) are essential for cerebroprotection by endogenous progesterone and by progesterone treatment. The identification of PR as a potential drug target for stroke therapy opens new therapeutic indications for selective synthetic progestins. Nestorone® (16-methylene-17α-acetoxy-19-nor-pregn-4-ene-3, 20-dione, also known as segesterone acetate) is a 19-norprogesterone derivative that more potently targets PR than progesterone. The objective of this study was to evaluate the cerebroprotective efficiency of intranasal administration of Nestorone after middle cerebral occlusion (MCAO) in mice. We show here that intranasal administration is a very efficient route to achieve a preferential delivery of Nestorone to the brain and confers a slow elimination and a sustained bioavailability. Furthermore, intranasal administration of Nestorone (at 0.08 mg/kg) improved the functional outcomes and decreased the ischemic lesion in male but not in female mice at 48 h post MCAO. Use of PRNesCre mice, selectively lacking expression of PR in neural cells, and their control PRloxP/loxP littermates showed that the cerebroprotective effects of Nestorone in male mice depended on neural PR as they were not observed in PRNesCre mice. Our findings show that intranasal delivery of Nestorone may be an efficient strategy to promote recovery after stroke in males and confirm the key role of PR in cerebroprotection. Furthermore, they point to sex differences in the response to Nestorone treatment and emphasize the necessity to include males and females in experimental studies.

Nestorone® , a 19nor-progesterone derivative boosts remyelination in an animal model of demyelination.

INTRODUCTION: We previously showed that Nestorone® (NES), a synthetic progestin structurally related to progesterone, stimulated remyelination of the corpus callosum in a Cuprizone (CUP) mouse model of demyelination in intact females by promoting replenishment with mature oligodendrocytes (OL) (Glia. 2015;63:104-117). Here, we further investigated the underlying mechanisms of this promyelinating effect. METHODS: We explored whether NES, applied subcutaneously through Alzet mini-osmotic pumps, regulates specific transcription factors involved in oligodendrocyte progenitor cell (OPC) proliferation and their differentiation into mature OL, using RT-qPCR and Western Blot analysis. RESULTS: Our present data show that in comparison to controls, a one-week treatment with NES, through Alzet mini-osmotic pumps, enhanced the production of three relevant transcription factor mRNAs encoding Olig2, Myt1, and Sox17. After 3 weeks, NES treatment reversed the effect of CUP on the levels of corresponding Olig2, Myt1, and Sox17 proteins. Moreover, in mice receiving NES + Estradiol (E2) co-treatment, levels of Olig2, Myt1, and Sox17 proteins did not change as compared to NES alone. CONCLUSION: NES alone or with E2 increased the levels of transcription factors, essential for myelin synthesis.

Simultaneous assay of segesterone acetate (Nestorone®), estradiol, progesterone, and estrone in human serum by LC-MS/MS.

OBJECTIVE: To develop a method to simultaneously quantify the synthetic contraceptive progestin segesterone acetate (Nestorone®, NES) and the endogenous steroid hormones estradiol (E2), progesterone (P4), and estrone (E1) in human serum samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). STUDY DESIGN: We analyzed 615 serum samples collected from 67 reproductive-age women actively using a contraceptive vaginal ring (CVR) designed to release NES (200 mcg/d) and E2 (75-200 mcg/d). Samples were taken prior to and up to 30 days after CVR insertion and analyzed for concentrations of NES, E2, P4, and E1 in human serum using a Shimadzu Nexera-LCMS-8050 LC-MS/MS platform. Precision, accuracy, and sensitivity for all analytes were determined across multiple assays. RESULTS: The assay ranges for NES, E2, P4, and E1 in this analytical method were 10 pg/mL to 10 ng/mL with a lower limit of quantification of 10 pg/mL for all targets. Assay precisions were less than or equal to 14.5% and accuracies ranged from 87.0% to 110.8%. When applied to the 615 clinical samples, 550 samples had quantifiable concentrations of NES (value range 0.014-1471 ng/mL). Similarly, 595 samples had quantifiable concentrations of E2 (0.010-0.312 ng/mL), 596 samples had quantifiable concentrations of P4 (0.010-5.791 ng/mL), and 609 samples had quantifiable concentrations of E1 (0.010-0.416 ng/mL). CONCLUSIONS: The LC-MS/MS platform results in a robust, accurate, and sensitive method for the simultaneous quantification of NES and endogenous steroid hormones in human serum. IMPLICATIONS: The analytical method described allows for the simultaneous quantification of NES and endogenous steroids and can be used to monitor NES concentrations during clinical trials and subject adherence to treatment with NES.

The hypertensiogenetic steroid 19-nor-progesterone does not influence cortisol inactivation by 11beta-hydroxysteroid dehydrogenase type 2.

19-nor-progesterone (19-nor-P) has the characteristics of a potent mineralocorticoid in adrenalectomized or salt-loaded rats and is capable of causing hypertension. In human placenta, progesterone is converted to 19-hydroxy-progesterone, a precursor of 19-nor-P. In some states of pregnancy hypertension, 19-nor-P may inhibit renal 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), thus allowing cortisol to bind to the mineralocorticoid receptor (MR). Therefore, we investigated the ability of 19-nor-P to inhibit human 11beta-HSD2. Fetal kidney cells (HEK 293) were transfected with human 11beta-HSD2 and incubated with increasing concentrations of 19-nor-P, labelled and unlabelled cortisol. Steroids were extracted, separated by TLC, and radioactivity was measured using a TLC scanner. 19-nor-P treatment did not significantly reduce 11beta-HSD2 activity (430 to 300 pmol/mg protein/h) in the range of tested concentrations. In conclusion, 19-nor-P did not inhibit human 11beta-HSD2 and seems not to be involved in human hypertension. Nevertheless, 19-nor-P may be converted by extra-adrenal tissues into 19-nor-deoxycorticosterone (DOC) or 19-nor-corticosterone, which are potent mineralocorticoids and may be involved in the pathogenesis of hypertension during pregnancy.

Preventing secondary exposure to women from men applying a novel nestorone/testosterone contraceptive gel.

BACKGROUND: Testosterone (T)/Nestorone (NES) combination gel is a potential transdermal male contraceptive that suppresses gonadotropins and spermatogenesis. Transfer of transdermal T from men to women can be prevented by washing or covering application sites with clothing. OBJECTIVES: We hypothesized that showering or wearing a shirt over gel application sites would prevent secondary exposure of T and NES to a woman after close skin contact. MATERIALS AND METHODS: Twelve healthy male and 12 healthy female participants were recruited. Men applied T/NES 62 mg/8 mg gel to their shoulders and upper arms. Two hours after application, female partners rubbed the application site for 15 min. Exposure in the female partner was assessed under three conditions: a shirt covered the application site; the man showered prior to skin contact; or without intervention to reduce transfer. Serum T and NES concentrations were measured by LC-MS/MS in serial blood samples for 24 h after gel exposure. MAIN OUTCOMES: Change in female serum T and NES levels as measured by average concentration over 24 h (Cavg ). RESULTS: Median female serum T Cavg was 23.9 ng/dL (interquartile range, 19.3, 33.9) with the shirt barrier and 26.7 ng/dL (20.7, 33.9) after showering, which was higher than baseline 20.9 ng/dL (16.7, 25.0), both p < 0.03) but lower than without intervention (58.2 ng/dL [30.9, 89.1], both p < 0.01). Female serum NES Cavg and maximum concentration were below the lower limit of quantification with the shirt barrier and after showering, but increased without intervention in six of 12 women (maximum concentration <60 pg/mL). Men had lower average serum NES levels after showering (47 pg/ml [20, 94] compared to no intervention (153.3 pg/mL [51, 241], p < 0.02). CONCLUSION: Secondary transfer of T and NES occurs after intensive skin contact with the gel application site. Secondary transfer is decreased by a shirt barrier or showering before contact.

Beyond contraception and hormone replacement therapy: Advancing Nestorone to a neuroprotective drug in the clinic.

Neurological diseases such as ischemic stroke can be debilitating and have limited treatments available. The progestin Nestorone® (segesterone acetate) has been evaluated for use in birth control and hormone replacement therapy due to its potency and high affinity for the progesterone receptor. Interestingly, Nestorone also exerts neuroprotection in animals afflicted with various central nervous system diseases, including stroke, which implicates its potential for treating these maladies in clinical settings. In fact, a recent Brain Research paper by Tanaka and colleagues demonstrates Nestorone's ability to reduce infarct sizes and preclude functional impairments in rats subjected to ischemic stroke. This commentary highlights Nestorone's properties as a progestin, its neuroprotective capabilities in animal studies, and how the Tanaka team's findings and previous clinical trials contribute to Nestorone's translation into a therapeutic agent for stroke and other neurological diseases.

Bone turnover markers in women participating in a dose-finding trial of a contraceptive vaginal ring releasing Nestorone and estradiol.

OBJECTIVE: To evaluate changes in the bone turnover markers CTx and P1NP during 6 months' use of novel continuous contraceptive vaginal rings delivering Nestorone (NES) 200 mcg/day and three doses of estradiol (E2) (10, 20, and 40 mcg/day). STUDY DESIGN: This randomized trial enrolled 189 women who used two consecutive vaginal rings over 180 days. Frequent blood sampling permitted analysis of NES, E2, CTx and P1NP concentrations. The bone-turnover marker analyses included only women with complete sampling and excluded women with characteristics that might interfere with accurate measurement of bone markers such as afternoon sampling, poor ring compliance or recent pregnancy. We evaluated the change from baseline to 6 months in CTx and P1NP, stratified by ring dose and by average circulating E2 concentrations. RESULTS: One hundred fifty-one women completed the study, and 82 women had complete data available for the bone marker analyses; the three dosage groups were balanced with regard to baseline characteristics. E2 concentrations remained low throughout treatment, regardless of which dose ring the participant used. Individual CTx changes from baseline averaged 27±56% (p<.01). Similarly, individual P1NP changes averaged 11±33% (p=.04). These increases were within the premenopausal reference ranges, and unrelated to treatment dose or to circulating E2 concentrations. CONCLUSIONS: The low E2 dose of these rings was associated with low E2 concentrations and modest increases in serum bone turnover makers. Because we have only 6-month bone turnover markers and no direct evidence of bone loss or bone density change, these results must be interpreted with caution. IMPLICATIONS: Nestorone, a 19-norprogesterone derivative, leads to complete ovarian suppression, which should yield excellent contraceptive effectiveness. To prevent potential adverse effects on bone, the NES contraceptive ring should be combined with higher doses of E2 than were assessed in this study.

Combined nestorone-testosterone gel suppresses serum gonadotropins to concentrations associated with effective hormonal contraception in men.

BACKGROUND: Novel male-based contraceptives are needed to broaden family planning choices. A progestin, Nestorone® (Nes) gel, plus a testosterone (T) gel suppresses sperm concentrations to levels associated with effective contraception in normal men. However, administration of two gels on different parts of the body daily is impractical. OBJECTIVE: Compare the effectiveness of daily application of a single, combined 8.3 mg Nes-62.5 mg T gel (Nes-T) vs. 62.7 mg T gel to suppress serum FSH and LH concentrations to ≤1.0 IU/L (a threshold associated with suppression of sperm concentrations to ≤1 million and effective contraception) and to compare the pharmacokinetics of serum Nes and T concentrations between the gel groups. DESIGN: We conducted a 28-day, double-blind, controlled trial of 44 healthy men randomized to daily Nes-T or T gel with measurement of hormones at baseline, treatment, and recovery and during 24-h pharmacokinetic studies on days 1 and 28 of treatment. RESULTS: Of the subjects who met pre-defined inclusion criteria, 84% of the Nes-T group suppressed serum gonadotropin concentrations to ≤1.0 IU/L at days 21-28 vs. 16.7% in the T group (p < 0.001). On day 1, Nes concentrations rose significantly above baseline by 2 h and continued to rise up to 24 h after Nes-T gel application. Nes concentrations were not detectable in the T group. Serum total T concentrations rose and were significantly higher in the T gel group compared to the Nes-T group at 24 h on day 1 and days 11, 14, and 21 (p < 0.01). There were no serious adverse events in either group. About 80% of the subjects reported satisfaction with both gels. CONCLUSION: Daily Nes-T gel effectively and safely suppresses serum gonadotropins and is acceptable to most men. It should be studied further in efficacy trials of hormonal male contraception.

Nestorone exerts long-term neuroprotective effects against transient focal cerebral ischemia in adult male rats.

Progesterone (P4) exerts long-term neuroprotective effects in animal models of stroke, and P4 receptors play a crucial role in this neuroprotection. However, it currently remains unclear whether the activation of P4 receptors alone is sufficient to exert long-term neuroprotection because P4 exhibits other steroidogenic and GABAergic activities via several of its metabolites. Nestorone is a potent selective P4 receptor agonist without other steroidogenic and GABAergic activities. Therefore, we examined the effects of nestorone in adult male rats subjected to transient middle cerebral artery occlusion (MCAO). The dose-response relationship of nestorone showed that the 6-h post-ischemic administration of 10 µg/kg nestorone resulted in greater reductions in infarct sizes 48 h after MCAO than the other two doses tested (5 and 80 µg/kg), and this dose of nestorone significantly decreased astrocyte activation in the peri-infarct cortical region. Moreover, 10 µg/kg nestorone significantly prevented functional impairments on the 28th and 29th days and slightly reduced infarct size on the 30th day after MCAO. The present results suggest that the activation of P4 receptors alone is sufficient to exert neuroprotection against transient cerebral ischemia in adult male rats; therefore, nestorone is a promising agent in post-stroke treatment due to its potent progestational effects without other steroid-related activities.

Differential metabolism of clinically-relevant progestogens in cell lines and tissue: Implications for biological mechanisms.

Steroid hormones regulate a variety of physiological processes, including reproductive function, and are widely used in hormonal therapy. Synthetic progestogens, or progestins, were designed to mimic progesterone (P4) for use in contraception and hormonal replacement therapy in women. Medroxyprogesterone acetate (MPA) and norethisterone (NET) are the most widely used injectable contraceptives in the developing world, while other progestins such as levonorgestrel (LNG), etonogestrel (ETG) and nestorone (NES) are used in or being developed for other forms of contraception. As concerns remain about the most appropriate choice of progestin and dosage, and the associated side-effects, the mechanisms and biological effects of progestins are frequently investigated in various in vitro mammalian cell line and tissue models. However, whether progestogens are differentially metabolised in different cell types in vivo or in vitro is unknown. For nine mammalian cell lines commonly used to investigate progestogen mechanisms of action, we developed and validated an ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) protocol for simultaneously quantifying the metabolism of the above-mentioned steroids. We show for the first time that, while 50-100% of P4 was metabolised within 24 h in all cell lines, the metabolism of the progestins is progestin- and cell line-specific. We also show that MPA and NET are significantly metabolised in human cervical tissue, but to a lesser extent than P4. Taken together, our findings suggest that differential progestogen metabolism may play a role in cell-specific therapeutic and side-effects. Relative affinities for binding to steroid receptors as well as potencies, efficacies and biocharacters for transcriptional activity of progestins, relative to P4, are most frequently determined using some of the cell lines investigated. Our results, however, suggest that differential metabolism of progestins and P4 may confound these results. In particular, metabolism may under-estimate the receptor-mediated intrinsic in vitro binding and dose-response values and predicted endogenous physiological effects of P4.

Progesterone receptor activation regulates seizure susceptibility.

OBJECTIVE: Progesterone is a potent neuromodulator that exerts effects on the brain through neurosteroids, progesterone receptors (PRs), and other molecules. Whether PR activation regulates seizures is not known. We determined whether PR activation increased seizure susceptibility. METHODS: Adult female rats that developed epilepsy following lithium-pilocarpine-induced status epilepticus (SE) were used. Seizures were recorded by continuous-video EEG and read by an individual blinded to the treatment of the animals. The animals were treated for a week with progesterone (50 mg/kg per day), and the effect of progesterone withdrawal on seizure frequency was assessed during the subsequent week. During the week of progesterone treatment, the animals were treated with PR antagonist RU-486 (10 mg/kg per day) or a vehicle control, which was administered 30 min before progesterone. In another set of animals, we determined the effect of the PR agonist Nestorone (3 mg/kg per day) on seizure frequency. The animals were treated with Nestorone or vehicle for a week, and seizure frequencies at baseline and during the treatment week were compared. RESULTS: Progesterone withdrawal induced twofold increase in seizures in 57% of animals (n = 14). RU-486 treatment in combination with progesterone, prevented this increase, and a smaller fraction of animals (17%) experienced withdrawal seizures (n = 13). The specific activation of PRs by Nestorone also increased the seizure frequency. Forty-six percent (n = 14) of Nestorone-treated animals experienced at least a 50% increase in seizures compared to only 9% of the vehicle-treated animals (n = 11). INTERPRETATION: PR activation increased seizure frequency in epileptic animals. Thus, PRs may be novel targets for treating catamenial epilepsy.