In vitro exposure to environmentally relevant concentrations of norgestrel affects sperm physiology and reproductive success of the Pacific oyster Crassostrea gigas.

Progestins in aquatic environments are of increasing concern, as shown by the results of toxicological studies on adult invertebrates with external fertilization. However, their potential effects on the gametes and reproductive success of such animals remain largely unknown. Thus, the current study assessed the effect of in vitro exposure of environmentally relevant concentrations (10 ng/L and 1000 ng/L) of norgestrel (NGT) on the sperm of Pacific oyster Crassostrea gigas, analyzing sperm motility, ultrastructure, mitochondrial function, ATP status, characteristic enzyme activities, and DNA integrity underlying fertilization and hatching success. The results showed that NGT increased the percentage of motile sperm by elevating intracellular Ca2+ levels, Ca2+-ATPase activity, creatine kinase activity, and ATP content. Although superoxide dismutase activity was enhanced to eliminate reactive oxygen species generated by NGT, oxidative stress occurred, as indicated by the increase in malonaldehyde content and damage to plasma membranes and DNA. As a consequence, fertilization rates decreased. However, hatching rates did not alter significantly, possibly as a result of DNA repair processes. This study demonstrates oyster sperm as a useful, sensitive tool for toxicological research of progestins and provides ecologically relevant information on reproductive disturbance in oysters resulting from exposure to NGT.

Norgestrel causes digestive gland injury in the clam Mactra veneriformis: An integrated histological, transcriptomics, and metabolomics study.

The potential adverse effects of progestins on aquatic organisms, especially non-target species, are of increasing concern worldwide. However, the effect and mechanism of progestin toxicity on aquatic invertebrates remain largely unexplored. In the present study, clams Mactra veneriformis were exposed to norgestrel (NGT, 0, 10, and 1000 ng/L), the dominant progestin detected in the aquatic environment, for 21 days. NGT accumulation, histology, transcriptome, and metabolome were assessed in the digestive gland. The bioconcentration factor (BCF) was 386 and 268 in the 10 ng/L NGT group and 1000 ng/L NGT group, respectively, indicating efficient accumulation of NGT in the clams. Histological analysis showed that NGT led to the swelling of epithelial cells and blurring of the basement membrane in the digestive gland. Differentially-expressed genes and KEGG pathway enrichment analysis using a transcriptomic approach suggested that NGT primarily disturbed the detoxification system, antioxidant defense, carbohydrate and amino acid metabolism, and steroid hormone metabolism, which was consistent with the metabolites analyzed using a metabolomic approach. Furthermore, we speculated that the oxidative stress caused by NGT resulted in histological damage to the digestive gland. This study showed that NGT caused adverse effects in the clams and sheds light on the mechanisms of progestin interference in aquatic invertebrates.

Synergistic effects of EP-1 and ivermectin mixture (iEP-1) to control rodents and their ectoparasites.

BACKGROUND: Ectoparasites of rodents play significant roles in disease transmission to humans. Conventional poisoning potentially reduces the population densities of rodents, however, they may increase the ectoparasite loads on the surviving hosts. EP-1 has been shown to have anti-fertility effects on many rodent species, while ivermectin is effective in controlling ectoparasites. In this study, we examined the combined effects of EP-1 and ivermectin mixture (iEP-1) baits on rodents and their corresponding flea/tick loads. RESULTS: In males, the weight of testis, epididymis, and seminiferous vesicle were reduced to less than 33%, 25%, and 17%, respectively, compared to the control group following administration of iEP-1 for 7 days. The weight of the uterus increased by approximately 75%. After 5 days of iEP-1 intake, all ticks were killed, whereas 94% of fleas on mice died after 3 days of bait intake. In the field test near Beijing, the flea index was reduced by more than 90% after 7 days of iEP-1 bait delivery. In a field test in Inner Mongolia, the weights of testis, epididymis, and seminiferous vesicle were significantly reduced by 27%, 32%, and 57%, respectively, 2 weeks after iEP-1 bait delivery. Approximately 36% rodents exhibited obvious uterine oedema accompanied by a weight increase of about 150%. The flea index was reduced by over 90%. CONCLUSION: Our results indicated that iEP-1 is a promising treatment for reducing the abundance of both small rodents and their ectoparasites; this will be effective for managing rodent damage and transmission of rodent-borne diseases associated with fleas and ticks. © 2022 Society of Chemical Industry.

The paradigm of norgestimate: a third-generation testosterone-derivative progestin with a peripheral anti-androgenic activity and the lowest risk of venous thromboembolism.

INTRODUCTION: Norgestimate (NGM) is a testosterone derivative with peculiar receptor activities. AREAS COVERED: This is a narrative review of the available data on the pharmacotherapy of NGM in combined hormonal contraceptives (CHCs) in terms of contraceptive efficacy, venous thromboembolism (VTE) risk, safety, tolerability and bleeding patterns. A comprehensive literature review was conducted in August 2020 using PubMed with the keyword 'norgestimate'. EXPERT OPINION: NGM shows a mild estrogenic activity associated with anti-mineralocorticoid and anti-androgenic properties, largely responsible for the cardiovascular safety profile. The anti-androgenic property depends on the androgen receptor (AR) nuclear translocation (AR trafficking and its subnuclear distribution), the inhibition of 5α-reductase activity (it possesses higher activity compared to other available progestins), and the increase on sexual hormone binding globulin (SHBG) levels if combined with an estrogenic counterpart. NGM is one of the molecules that best modulates the power of ethinyl-estradiol on the thromboembolic risk, being associated with the lowest VTE risk between different CHCs. NGM has the advantage of retaining peripheral anti-androgenic activity, demonstrated by the impact on lipid and glucose metabolism, and it should be preferred if compared with other similar progestins of the same class of risk which are much more androgenic, such as levonorgestrel.

Norgestrel, a Progesterone Analogue, Promotes Significant Long-Term Neuroprotection of Cone Photoreceptors in a Mouse Model of Retinal Disease.

Purpose: Retinitis pigmentosa (RP) refers to a group of inherited blinding retinal diseases, whereby the death of mutated rod photoreceptors is followed closely by the death of cone photoreceptors. Cone cell death can be hugely debilitating as color/daytime vision becomes impaired. Thus, treatments that are effective against cone cell death are urgently needed. Our research has been working toward development of a neuroprotective treatment for RP. We have previously demonstrated significant neuroprotective properties of norgestrel, a progesterone analogue, in the mouse retina. The current study further investigates the potential of norgestrel as a treatment for RP, with a focus on long-term preservation of cone photoreceptors. Methods: Using the well-established rd10 mouse model of RP, we administered a norgestrel-supplemented diet at postnatal day (P)30, following widespread loss of rod photoreceptors and at the outset of cone degeneration. We subsequently assessed cone cell morphology and retinal function at P50, P60, and P80, using immunohistochemistry, electroretinograph recordings, and optomotor testing. Results: While cone cell degeneration was widespread in the untreated rd10 retina, we observed profound preservation of cone photoreceptor morphology in the norgestrel-treated mice for at least 50 days, out to P80. This was demonstrated by up to 28-fold more cone arrestin-positive photoreceptors. This protection transpired to functional preservation at all ages. Conclusions: This work presents norgestrel as an incredibly promising long-term neuroprotective compound for the treatment of RP. Crucially, norgestrel could be used in the mid-late stages of the disease to protect remaining cone cells and help preserve color/daytime vision.

A Multi-Center, Open-Label, Pharmacokinetic Drug Interaction Study of Erenumab and a Combined Oral Contraceptive in Healthy Females.

BACKGROUND: Erenumab is a human anti-calcitonin gene-related peptide monoclonal antibody developed for migraine prevention. Migraine predominately affects women of childbearing age; thus, it is important to determine potential drug-drug interactions between a common oral contraceptive and drugs used to treat migraine. OBJECTIVES: We sought to evaluate potential drug-drug interactions between erenumab and a common oral contraceptive. METHODS: Healthy women received three cycles of a norgestimate/ethinyl estradiol-containing oral contraceptive with a single 140-mg subcutaneous dose of erenumab during cycle three. Norgestimate metabolites (norgestrel and norelgestromin) and ethinyl estradiol pharmacokinetics were evaluated in the absence and presence of erenumab. Primary endpoint was peak plasma concentration (Cmax) and area under concentration-time curve from time 0 to 24 h (AUCtau). Luteinizing hormone, follicle-stimulating hormone, and progesterone concentrations were evaluated as pharmacodynamic markers. RESULTS: Erenumab did not influence the pharmacokinetics of norelgestromin, norgestrel, or ethinyl estradiol. Least-squares mean estimates (90% confidence interval) for Cmax ratios were 1.05 (0.90-1.23), 1.06 (0.97-1.16), and 1.04 (0.88-1.22) for norelgestromin, norgestrel, and ethinyl estradiol, respectively. Respective AUCtau ratios were 1.02 (0.94-1.12), 1.03 (0.96-1.10), and 1.02 (0.91-1.14). Luteinizing hormone, follicle-stimulating hormone, and progesterone concentrations were similar after exposure to oral contraceptive alone and with erenumab. CONCLUSION: Erenumab did not alter the pharmacokinetics of the active components of an estrogen/progestin combination oral contraceptive. Thus, no change in contraceptive efficacy is expected with erenumab. TRIAL REGISTRATION: ClinicalTrials.gov NCT02792517.

Reproductive effects of synthetic progestin norgestrel in zebrafish (Danio rerio).

The aim of this study was to assess the adverse effects of synthetic progestin norgestrel (NGT) on the reproduction of zebrafish by measuring the egg production, histology and transcriptional expression profiles along the hypothalamic-pituitary-gonadal (HPG) axis in adult zebrafish. After a pre-exposure period of 7 days, adult zebrafish were exposed to 6, 29 and 69 ng L-1 NGT for 21 days. The results showed that exposure to 69 ng L-1 NGT led to a significant up-regulation of follicle stimulating hormone, beta polypeptide (fshb), luteinizing hormone, beta polypeptide (lhb), progesterone receptor (pgr), estrogen receptor 1 (esr1) and androgen receptor (ar) genes in the brains, as well as significant up-regulation of hydroxysteroid 20-beta dehydrogenase (hsd20b) and hydroxysteroid 11-beta dehydrogenase 2 (hsd11b2) genes and down-regulation of 11-beta-hydroxylase (cyp11b) gene in the ovaries of females. In the testes of males, an overall down-regulation of steroidogenic acute regulatory protein (star), cytochrome P450-mediated side-chain cleavage enzyme (cyp11a1), cyp11b, hsd20b, hydroxysteroid 17-beta dehydrogenase type 3 (hsd17b3), hsd11b2 and ar genes were observed following exposure to different treatments of NGT. These transcriptional alterations imply that NGT could exhibit the potent progestogenic and androgenic activities in zebrafish. Egg production as well as histology in the ovaries and testes was not affected by NGT. Taken together, the overall results demonstrated that NGT could significantly affect transcriptional expression levels of genes related to HPG axis in zebrafish, and whether that change translates to additional physiological effects is needed further research.

Microglial-induced Müller cell gliosis is attenuated by progesterone in a mouse model of retinitis pigmentosa.

Norgestrel, a progesterone analogue, has demonstrated neuroprotective effects in a mouse model of retinitis pigmentosa. Neuroprotection is achieved in part through Norgestrels anti-inflammatory properties, alleviating detrimental microglial activity. Gliosis is a feature of many neurodegenerative diseases of the retina, including retinitis pigmentosa. Müller glia, a type of macroglia found in the retina, are major contributors of gliosis, characterized by the upregulation of glial fibrillary acidic protein (GFAP). Microglia-Müller glia crosstalk has been implicated in the initiation of gliosis. In the rd10 retina, increased microglial activity and gliotic events are observed prior to the onset of photoreceptor loss. We hypothesized that Norgestrels dampening effects on harmful microglial activity would consequently impact on gliosis. In the current study, we explore the role of microglia-Müller glia crosstalk in degeneration and Norgestrel-mediated neuroprotection in the rd10 retina. Norgestrels neuroprotective effects in the rd10 retina coincide with significant decreases in both microglial activity and Müller cell gliosis. Using a Müller glial cell line, rMC-1, and isolated microglia, we show that rd10 microglia stimulate GFAP production in rMC-1 cells. Norgestrel attenuates gliosis through direct actions on both microglia and Müller glia. Norgestrel reduces the release of harmful stimuli from microglia, such as interferon-γ, which might otherwise signal to Müller glia and stimulate gliosis. We propose that Norgestrel also targets Müller cell gliosis directly, by limiting the availability of pSTAT3, a known transcription factor for GFAP. These findings highlight an important aspect to Norgestrels neuroprotective effects in the diseased retina, in combating Müller cell gliosis.

Comparison of estrus synchronization by controlled internal drug release device (CIDR) and adhesive transdermal progestin patch in postpartum beef cows.

Estrous synchronization with progesterone based protocols has been essentially used in cattle industry. Although intravaginal devices have been commonly used, this technique may induce vaginitis. This study aimed at examining the efficiency of novel transdermal progestin patch on follicle development and comparing the progestin patch versus CIDR device on estrous synchronization, complication at treated site and pregnancy in beef cattle. In experiment 1, seven beef cows were treated with an adhesive transdermal progestin patch on the ventral surface of the proximal part of the tail for 7 days. The cows were daily examined the follicular development using ultrasonography starting on Day 0 till 3 days after hormone removal. Experiment 2, forty beef cows were divided into two equal groups (20 cows per group). The cows randomly allocated to received either vaginal insertion of CIDR (n = 20) or treated with an adhesive transdermal progestin patch (n = 20). The levels of plasma progesterone during the experiment and the numbers of standing estrous cows were recorded. Timed artificial inseminated (TAI) was performed at 60 h after CIDR or patch termination. Pregnancy rates were determined at 60 days after TAI. Experiment 1 revealed that the novel transdermal progestin patch could efficiently control follicular growth. All the seven treated cows had dominant follicle upon dermal patch removal indicating the effectiveness of the progestin patch. In experiment 2, the percentages of cows exhibited standing estrus were similar between transdermal patch (72.22%) and CIDR (70.00%). The levels of plasma progesterone during CIDR treatment were significantly higher (4.06 ± 1.65 ng/mL on Day 1 and 3.62 ± 1.60 ng/mL on Day 7) compared with transdermal patch (2.60 ± 1.43 ng/mL on Day 1 and 1.81 ± 1.57 ng/mL on Day 7). Three cows treated with CIDR (15%) developed vaginitis while none of cows had physically dermal reaction at adhesive site. Cows synchronized with these two protocols had similar pregnancy rates (50.00%) following fixed time artificial insemination. It is concluded that transdermal progestin patch was equally effective in estrus synchronization as compared with traditional CIDR. However, the transdermal patch demonstrated less complication. This device should therefore be considered as an alternative method for estrus synchronization in postpartum beef cattle.

Pro-survival redox signalling in progesterone-mediated retinal neuroprotection.

Retinitis pigmentosa (RP) is a group of hereditary retinal diseases, characterised by photoreceptor cell loss. Despite a substantial understanding of the mechanisms leading to cell death, an effective therapeutic strategy is sought. Our laboratory has previously demonstrated the neuroprotective properties of Norgestrel, a progesterone analogue, in the degenerating retina, mediated in part by the neurotrophic factor basic fibroblast growth factor (bFGF). In other retinal studies, we have also presented a pro-survival role for reactive oxygen species (ROS), downstream of bFGF. Thus, we hypothesized that Norgestrel utilises bFGF-driven ROS production to promote photoreceptor survival. Using the 661W photoreceptor-like cell line, we now show that Norgestrel, working through progesterone receptor membrane complex 1 (PGRMC1); generates an early burst of pro-survival bFGF-induced ROS. Using the rd10 mouse model of RP, we confirm that Norgestrel induces a similar early pro-survival increase in retinal ROS. Norgestrel-driven protection in the rd10 retina was attenuated in the presence of antioxidants. This study therefore presents an essential role for ROS signalling in Norgestrel-mediated neuroprotection in vitro and demonstrates that Norgestrel employs a similar pro-survival mechanism in the degenerating retina.

Metabolite Identification, Reaction Phenotyping, and Retrospective Drug-Drug Interaction Predictions of 17-Deacetylnorgestimate, the Active Component of the Oral Contraceptive Norgestimate.

Ortho Tri-Cyclen, a two-drug cocktail comprised of ethinylestradiol and norgestimate (13-ethyl-17-acetoxy-18, 19-dinor-17α-pregn-4-en-20yn-3 oxime), is commonly prescribed to avert unwanted pregnancies in women of reproductive age. In vivo, norgestimate undergoes extensive and rapid deacetylation to produce 17-deacetylnorgestimate (NGMN), an active circulating metabolite that likely contributes significantly to norgestimate efficacy. Despite being of primary significance, the metabolism and reaction phenotyping of NGMN have not been previously reported. Hence, detailed biotransformation and reaction phenotyping studies of NGMN with recombinant cytochrome P450 (P450), recombinant uridine 5'-diphospho-glucuronosyltransferases, and human liver microsomes in the presence and absence of selective P450 inhibitors were conducted. It was found that CYP3A4 plays a key role in NGMN metabolism with a fraction metabolized (fm) of 0.57. CYP2B6 and to an even lesser extent CYP2C9 were also observed to catalyze NGMN metabolism. Using this CYP3A4 fm value, the predicted plasma concentration versus time area under the curve (AUC) change in NGMN using a basic/mechanistic static model was found to be within 1.3-fold of the reported NGMN AUC changes for four modulators of CYP3A4. In addition to NGMN, we have also elucidated the biotransformation of norgestrel (NG), a downstream norgestimate and NGMN metabolite, and found that CYP3A4 and UGT1A1 have a major contribution to the elimination of NG with a combined fm value of 1. The data presented in this paper will lead to better understanding and management of NGMN-based drug-drug interactions when norgestimate is coadministered with CYP3A4 modulators.

Transcriptional alterations induced by binary mixtures of ethinylestradiol and norgestrel during the early development of zebrafish (Danio rerio).

Synthetic estrogens and progestins are commonly used in human and veterinary medicine. After use, they reach aquatic environments via discharge of wastewaters from human and animals, thus posing potential risks to organisms. So far, very little is known about their combined effects in aquatic organisms. The aim of this study was to investigate the effects of binary mixtures of ethinylestradiol (EE2) and norgestrel (NGT) on embryonic zebrafish (Danio rerio) by measuring transcriptional alterations. Zebrafish embryos were exposed to EE2 and NGT alone or in combination at concentrations between 36 and 5513ngL-1 for 96h post-fertilization (hpf). The results showed that most of gene transcriptions of hypothalamic-pituitary-gonadal axis (e.g., Pgr, Mprα, Esr1, Esr2a, Vtg1, Ar, Cyp11b, Star, Gnrh3 and Fshb) and circadian rhythm signaling (e.g., Cry1a, Cry2a, Cry2b, Per3, Arntl1b, Arntl2, Clock1a, Cry3 and Cry4) displayed most pronounced alterations in the mixtures as compared to single EE2 and NGT exposures. This finding suggests exposure to the binary mixtures of EE2 and NGT produced significantly enhanced effects in fish as compared to single chemical exposures, and their coexistence could have significant environmental implications.

Fractalkine-CX3CR1 signaling is critical for progesterone-mediated neuroprotection in the retina.

Retinitis pigmentosa (RP) encompasses a group of retinal diseases resulting in photoreceptor loss and blindness. We have previously shown in the rd10 mouse model of RP, that rd10 microglia drive degeneration of viable neurons. Norgestrel, a progesterone analogue, primes viable neurons against potential microglial damage. In the current study we wished to investigate this neuroprotective effect further. We were particularly interested in the role of fractalkine-CX3CR1 signaling, previously shown to mediate photoreceptor-microglia crosstalk and promote survival in the rd10 retina. Norgestrel upregulates fractalkine-CX3CR1 signaling in the rd10 retina, coinciding with photoreceptor survival. We show that Norgestrel-treated photoreceptor-like cells, 661Ws, and C57 explants modulate rd10 microglial activity in co-culture, resulting in increased photoreceptor survival. Assessment of Norgestrel's neuroprotective effects when fractalkine was knocked-down in 661 W cells and release of fractalkine was reduced in rd10 explants confirms a crucial role for fractalkine-CX3CR1 signaling in Norgestrel-mediated neuroprotection. To further understand the role of fractalkine in neuroprotection, we assessed the release of 40 cytokines in fractalkine-treated rd10 microglia and explants. In both cases, treatment with fractalkine reduced a variety of pro-inflammatory cytokines. These findings further our understanding of Norgestrel's neuroprotective properties, capable of modulating harmful microglial activity indirectly through photoreceptors, leading to increased neuroprotection.

The synthetic progestin norgestrel modulates Nrf2 signaling and acts as an antioxidant in a model of retinal degeneration.

Retinitis pigmentosa (RP) is one of the most common retinal degenerative conditions affecting people worldwide, and is currently incurable. It is characterized by the progressive loss of photoreceptors, in which the death of rod cells leads to the secondary death of cone cells; the cause of eventual blindness. As rod cells die, retinal-oxygen metabolism becomes perturbed, leading to increased levels of reactive oxygen species (ROS) and thus oxidative stress; a key factor in the secondary death of cones. In this study, norgestrel, an FDA-approved synthetic analog of progesterone, was found to be a powerful neuroprotective antioxidant, preventing light-induced ROS in photoreceptor cells, and subsequent cell death. Norgestrel also prevented light-induced photoreceptor morphological changes that were associated with ROS production, and that are characteristic of RP. Further investigation showed that norgestrel acts via post-translational modulation of the major antioxidant transcription factor Nrf2; bringing about its phosphorylation, subsequent nuclear translocation, and increased levels of its effector protein superoxide dismutase 2 (SOD2). In summary, these results demonstrate significant protection of photoreceptor cells from oxidative stress, and underscore the potential of norgestrel as a therapeutic option for RP.

A positive feedback loop between progesterone and microsomal prostaglandin E synthase-1-mediated PGE2 promotes production of both in mouse granulosa cells.

Microsomal prostaglandin E synthase-1 (mPGES-1) is primarily expressed in granulosa cells (GCs) in the preovulatory follicle. Both prostaglandin E2 (PGE2) and progesterone (P4) are implicated in various reproductive functions. Here, we demonstrate that mPges-1 may be a direct downstream target gene of the P4 receptor and P4-stimulated PGE2 secretion can stimulate P4 production in a newly generated mouse GC line (GtsT). Treatment of GtsT cells with a P4 receptor agonist, norgestrel, markedly increased mPGES-1 expression detected by RT-PCR analysis. PGE2 secretion measured by an enzyme-linked immunosorbent assay was enhanced by P4 treatment. Luciferase assays revealed that the proximal promoter region of the mPges-1 gene was responsible for the effects of P4 treatment. Conversely, PGE2 treatment stimulated P4 secretion, which coordinated with mRNA expression of steroidogenic acute regulatory protein. Taken together, P4 may regulate mPGES-1 expression to increase PGE2 secretion and in turn P4 production. An autocrine loop between P4 and PGE2 might function to maintain the increased levels of both in GCs.

The synthetic progestin norgestrel acts to increase LIF levels in the rd10 mouse model of retinitis pigmentosa.

PURPOSE: Retinal degenerative conditions affect thousands of people worldwide. Retinitis pigmentosa (RP) is among the most common, but it is currently incurable. It is characterized by the progressive death of photoreceptor cells, eventually leading to blindness. Neurotrophic factors play an important role in such retinopathies, and much research has been performed on their use as treatments. Our group previously demonstrated the ability of the synthetic progestin norgestrel to rescue photoreceptors from cell death, the mechanism of which is believed to include upregulation of the neurotrophic factor basic fibroblast growth factor (bFGF). The objective of the present study was to investigate whether the protection provided by norgestrel is likely to be mediated by other neurotrophins. METHODS: The 661W photoreceptor cells and retinal explants from P30 to P40 wild-type (wt) C57BL/6 mice were treated with norgestrel over time. Homozygous rd10/rd10 mice that mimic the human form of RP were fed either a control or a norgestrel-containing diet. Changes in neurotrophic factor expression in response to norgestrel were detected with real-time PCR, western blotting, or immunofluorescence staining. Using specific siRNA, leukemia inhibitory factor (Lif) expression was knocked down in 661W photoreceptor cells that were stressed by serum starvation. Cells were treated with norgestrel followed by measurement of cell viability with (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay. RESULTS: LIF, a potent neuroprotective cytokine, was found to be upregulated in response to norgestrel in vitro and in vivo. Upregulation of LIF in degenerating rd10 retinas coincided with preservation of the photoreceptor layer. We also found LIF was necessary for the norgestrel-mediated rescue of stressed photoreceptor cells from cell death in vitro. CONCLUSIONS: LIF was upregulated in response to norgestrel in all models studied and is necessary for the protective effects of norgestrel in vitro. The increase in LIF expression in rd10 mice undergoing retinal degeneration was concurrent with rescue of the photoreceptor cell layer. These results highlight the ability of norgestrel to induce prosurvival molecules in the compromised retina, underlining norgestrel's potential as a viable drug for treatment of RP.

Metabolic Effects of a Commonly Used Combined Hormonal Oral Contraceptive in Women With and Without Polycystic Ovary Syndrome.

BACKGROUND: Data on combined hormonal oral contraceptives' (OCs) effects on metabolic changes in women with polycystic ovary syndrome (PCOS) have been conflicting and were predominantly based on OCs with cyproterone acetate (unavailable in the United States) Most studies did not include normal women as controls. We compared metabolic changes before and after an OC commonly used in the United States between women with and without PCOS. METHODS: Ten PCOS and 20 control women took ethinyl estradiol 35 µg and norgestimate 0.18/0.215/0.25 mg. Fasting glucose and insulin, area-under-the-curve (AUC) glucose and insulin, insulin sensitivity (homeostatic model assessment of insulin sensitivity index [HOMA-ISI] and Matsuda index), insulinogenic index (Δinsulin0-30 minutes/Δglucose0-30 minutes), blood pressure, and lipids were evaluated at baseline and after three cycles of OC. RESULTS: At baseline, PCOS women had lower insulin sensitivity (Matsuda index p = 0.0093, HOMA-ISI p = 0.0397), higher fasting insulin (p = 0.0495), fasting glucose (p = 0.0393), AUC insulin (p = 0.0023), and triglycerides (p = 0.0044) versus controls. Baseline AUC glucose did not differ between PCOS women and controls. After 3 months of OC use, glucose tolerance worsened in PCOS women versus controls (p = 0.0468). Higher baseline androgens were predictive of worsened glucose tolerance, and a reduction of AUC insulin during OC use. The insulinogenic index significantly decreased in PCOS women (p < 0.01), while fasting insulin and insulin resistance significantly worsened in control women. CONCLUSION: Women with PCOS exhibited worsened glucose tolerance (demonstrated by AUC glucose) after 3 months of a commonly used OC compared with control women. Larger studies with longer follow-up should confirm these findings.

The synthetic progesterone Norgestrel is neuroprotective in stressed photoreceptor-like cells and retinal explants, mediating its effects via basic fibroblast growth factor, protein kinase A and glycogen synthase kinase 3ß signalling.

The synthetic progesterone Norgestrel has been shown to have proven neuroprotective efficacy in two distinct models of retinitis pigmentosa: the rd10/rd10 (B6.CXBI-Pde6b(rd10)/J) mouse model and the Balb/c light-damage model. However, the cellular mechanism underlying this neuroprotection is still largely unknown. Therefore, this study aimed to examine the downstream signalling pathways associated with Norgestrel both in vitro and ex vivo. In this work, we identify the potential of Norgestrel to rescue stressed 661W photoreceptor-like cells and ex vivo retinal explants from cell death over 24 h. Norgestel is thought to work through an upregulation of neuroprotective basic fibroblast growth factor (bFGF). Analysis of 661W cells in vitro by real-time polymerase chain reaction (rt-PCR), enzyme-linked immunosorbent assay (ELISA) and Western blotting revealed an upregulation of bFGF in response to Norgestrel over 6 h. Specific siRNA knockdown of bFGF abrogated the protective properties of Norgestrel on damaged photoreceptors, thus highlighting the crucial importance of bFGF in Norgestrel-mediated protection. Furthermore, Norgestrel initiated a bFGF-dependent inactivation of glycogen synthase kinase 3ß (GSK3ß) through phosphorylation at serine 9. The effects of Norgestrel on GSK3ß were dependent on protein kinase A (PKA) pathway activation. Specific inhibition of both the PKA and GSK3ß pathways prevented Norgestrel-mediated neuroprotection of stressed photoreceptor cells in vitro. Involvement of the PKA pathway following Norgestrel treatment was also confirmed ex vivo. Therefore, these results indicate that the protective efficacy of Norgestrel is, at least in part, due to the bFGF-mediated activation of the PKA pathway, with subsequent inactivation of GSK3ß.

Evaluation of the effects of the weak CYP3A inhibitors atorvastatin and ethinyl estradiol/norgestimate on lomitapide pharmacokinetics in healthy subjects.

Lomitapide is a microsomal triglyceride transfer protein inhibitor approved as an adjunctive treatment for adult patients with homozygous familial hypercholesterolemia. Lomitapide is extensively metabolized via cytochrome P450 3A (CYP3A) and is a weak CYP3A inhibitor. Two phase 1 open-label, randomized (1:1), 2-arm drug interaction studies in healthy subjects assessed the effects of atorvastatin and ethinyl estradiol (EE)/norgestimate, both weak CYP3A inhibitors, on lomitapide pharmacokinetics with staggered (separated by 12 hours) or simultaneous administration. All subjects received a single dose of lomitapide (20 mg) in the evening on day 1. Atorvastatin (80 mg once daily, n = 32) or EE/norgestimate (0.035/0.25 mg once daily, n = 32) dosing was initiated on days 11 or 8, respectively, with evening (arm 1) or morning (arm 2) dosing; at steady state (days 15 or 22), a single lomitapide dose was administered; CYP3A inhibitor dosing continued for 6 days. Blood samples for pharmacokinetic analysis were taken until 168 hours postdose. With atorvastatin, lomitapide exposure was increased by approximately 2-fold and 1.3-fold, respectively, with simultaneous and staggered administration, respectively. Simultaneous and staggered EE/norgestimate and lomitapide administration resulted in an approximately 1.3-fold increase in lomitapide exposure. Reductions in lomitapide dose may be required for some patients when administered concomitantly with a weak CYP3A inhibitor.

Progesterone receptor signalling in retinal photoreceptor neuroprotection.

'Norgestrel', a synthetic form of the female hormone progesterone has been identified as potential drug candidate for the treatment of the degenerative eye disease retinitis pigmentosa. However, to date, no work has looked at the compound's specific cellular target. Therefore, this study aimed to identify the receptor target of Norgestrel and begin to examine its potential mechanism of action in the retina. In this work, we identify and characterize the expression of progesterone receptors present in the C57 wild type and rd10 mouse model of retinitis pigmentosa. Classical progesterone receptors A and B (PR A/B), progesterone receptor membrane components 1 and 2 (PGRMC1, PGRMC2) and membrane progesterone receptors α, ß and γ were found to be expressed. All receptors excluding PR A/B were also found in the 661W photoreceptor cell line. PGRMC1 is a key regulator of apoptosis and its expression is up-regulated in the degenerating rd10 mouse retina. Activated by Norgestrel through nuclear trafficking, siRNA knock down of PGRMC1 abrogated the protective properties of Norgestrel on damaged photoreceptors. Furthermore, specific inhibition of PGRMC1 by AG205 blocked Norgestrel-induced protection in stressed retinal explants. Therefore, we conclude that PGRMC1 is crucial to the neuroprotective effects of Norgestrel on stressed photoreceptors. The synthetic progestin 'Norgestrel' has been identified as a potential therapeutic for the treatment of Retinitis Pigmentosa, a degenerative eye disease. However, the mechanism behind this neuroprotection is currently unknown. In this work, we identify 'Progesterone Receptor Membrane Component 1' as the major progesterone receptor eliciting the protective effects of Norgestrel, both in vitro and ex vivo. This furthers our understanding of Norgestrel's molecular mechanism, which we hope will help bring Norgestrel one step closer to the clinic.