Publications by authors named "Philippe Liere"

50 Publications

Neuroprotective Effects of Testosterone in Male Wobbler Mouse, a Model of Amyotrophic Lateral Sclerosis.

Mol Neurobiol 2021 May 7;58(5):2088-2106. Epub 2021 Jan 7.

Laboratory of Neuroendocrine Biochemistry, Instituto de Biologia y Medicina Experimental-CONICET, Obligado 2490, 1428, Buenos Aires, Argentina.

Patients suffering of amyotrophic lateral sclerosis (ALS) present motoneuron degeneration leading to muscle atrophy, dysphagia, and dysarthria. The Wobbler mouse, an animal model of ALS, shows a selective loss of motoneurons, astrocytosis, and microgliosis in the spinal cord. The incidence of ALS is greater in men; however, it increases in women after menopause, suggesting a role of sex steroids in ALS. Testosterone is a complex steroid that exerts its effects directly via androgen (AR) or Sigma-1 receptors and indirectly via estrogen receptors (ER) after aromatization into estradiol. Its reduced-metabolite 5α-dihydrotestosterone acts via AR. This study analyzed the effects of testosterone in male symptomatic Wobblers. Controls or Wobblers received empty or testosterone-filled silastic tubes for 2 months. The cervical spinal cord from testosterone-treated Wobblers showed (1) similar androgen levels to untreated control and (2) increased levels of testosterone, and its 5α-reduced metabolites, 5α- dihydrotestosterone, and 3β-androstanediol, but (3) undetectable levels of estradiol compared to untreated Wobblers. Testosterone-treated controls showed comparable steroid concentrations to its untreated counterpart. In testosterone- treated Wobblers a reduction of AR, ERα, and aromatase and high levels of Sigma-1 receptor mRNAs was demonstrated. Testosterone treatment increased ChAT immunoreactivity and the antiinflammatory mediator TGFβ, while it lessened vacuolated motoneurons, GFAP+ astrogliosis, the density of IBA1+ microgliosis, proinflammatory mediators, and oxidative/nitrosative stress. Clinically, testosterone treatment in Wobblers slowed the progression of paw atrophy and improved rotarod performance. Collectively, our findings indicate an antiinflammatory and protective effect of testosterone in the degenerating spinal cord. These results coincided with a high concentration of androgen-reduced derivatives after testosterone treatment suggesting that the steroid profile may have a beneficial role on disease progression.
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http://dx.doi.org/10.1007/s12035-020-02209-5DOI Listing
May 2021

Progesterone and fetal-neonatal neuroprotection.

Best Pract Res Clin Obstet Gynaecol 2020 Nov 8;69:50-61. Epub 2020 Sep 8.

U1195 "Diseases and Hormones of the Nervous System", Inserm and University Paris-Saclay, 80, Rue Du Général Leclerc, 94276, Kremlin-Bicêtre, France.

The role of progesterone goes beyond the maintenance of pregnancy. The hormone, indeed, protects the developing fetal brain and influences its maturation. Metabolomes analyzed by mass spectrometric methods have revealed the great diversity of steroids in maternal plasma and fetal fluids, but their developmental significance remains to be investigated. Progesterone and its metabolites reach highest levels during the third trimester, when the brain growth spurt occurs: its volume triples, synaptogenesis is particularly active, and axons start to be myelinated. This developmental stage coincides with a period of great vulnerability. Studies in sheep have shown that progesterone and its metabolite allopregnanolone protect the vulnerable fetal brain. Work in rats and mice have demonstrated that progesterone plays an important role in myelin formation. These experimental studies are discussed in relation to preterm birth. Influences of progesterone on very early stages of neural development at the beginning of pregnancy are yet to be explored.
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http://dx.doi.org/10.1016/j.bpobgyn.2020.09.001DOI Listing
November 2020

Pregnane steroidogenesis is altered by HIV-1 Tat and morphine: Physiological allopregnanolone is protective against neurotoxic and psychomotor effects.

Neurobiol Stress 2020 May 29;12:100211. Epub 2020 Jan 29.

Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, 23298, USA.

Pregnane steroids, particularly allopregnanolone (AlloP), are neuroprotective in response to central insult. While unexplored , AlloP may confer protection against the neurological dysfunction associated with human immunodeficiency virus type 1 (HIV-1). The HIV-1 regulatory protein, trans-activator of transcription (Tat), is neurotoxic and its expression in mice increases anxiety-like behavior; an effect that can be ameliorated by progesterone, but not when 5α-reduction is blocked. Given that Tat's neurotoxic effects involve mitochondrial dysfunction and can be worsened with opioid exposure, we hypothesized that Tat and/or combined morphine would perturb steroidogenesis in mice, promoting neuronal death, and that exogenous AlloP would rescue these effects. Like other models of neural injury, conditionally inducing HIV-1 Tat in transgenic mice significantly increased the central synthesis of pregnenolone and progesterone's 5α-reduced metabolites, including AlloP, while decreasing central deoxycorticosterone (independent of changes in plasma). Morphine significantly increased brain and plasma concentrations of several steroids (including progesterone, deoxycorticosterone, corticosterone, and their metabolites) likely via activation of the hypothalamic-pituitary-adrenal stress axis. Tat, but not morphine, caused glucocorticoid resistance in primary splenocytes. In neurons, Tat depolarized mitochondrial membrane potential and increased cell death. Physiological concentrations of AlloP (0.1, 1, or 10 nM) reversed these effects. High-concentration AlloP (100 nM) was neurotoxic in combination with morphine. Tat induction in transgenic mice potentiated the psychomotor effects of acute morphine, while exogenous AlloP (1.0 mg/kg, but not 0.5 mg/kg) was ameliorative. Data demonstrate that steroidogenesis is altered by HIV-1 Tat or morphine and that physiological AlloP attenuates resulting neurotoxic and psychomotor effects.
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http://dx.doi.org/10.1016/j.ynstr.2020.100211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7109513PMC
May 2020

Dose-dependent and long-term cerebroprotective effects of intranasal delivery of progesterone after ischemic stroke in male mice.

Neuropharmacology 2020 06 6;170:108038. Epub 2020 Mar 6.

U1195 Inserm and University Paris-Sud and University Paris-Saclay, 80 rue du Général Leclerc, 94276 Kremlin-Bicêtre, France. Electronic address:

Intranasal administration is emerging as a very promising route to deliver therapeutics to the brain. We have recently shown that the intranasal delivery of progesterone at 8 mg/kg is neuroprotective after stroke in male mice. To explore the translational potential of intranasal progesterone treatment, we performed a dose-response study and analyzed outcomes at 48 h after middle cerebral artery occlusion (MCAO). The effects on functional outcomes at long-term were examined by using the optimal dose. In the first experiment, male C57BL/6JRj mice were treated with progesterone at 8, 16 or 24 mg/kg, or with placebo at 1, 6 and 24 h post-MCAO. Our results show that the dose of 8 mg/kg was optimal in counteracting the early histopathological impairments as well as in improving functional recovery. Steroid profiling in plasma showed that the dose of 8 mg/kg is the one that leads to sustained high levels of progesterone and its neuroactive metabolites. In the second experiment, the dose of 8 mg/kg was used and analyzes were performed at 2, 7 and 21 days post-MCAO. Progesterone increased survival, glycemia and body weight. Furthermore, progesterone decreased neurological deficits and improved performances of mice on the rotarod and pole as early as 2 days and up to 21 days post-MCAO. These findings show that intranasal administration of progesterone has a significant translational potential as a cerebroprotective treatment after stroke that can be effective to reduce mortality, to limit tissue and cell damage at the acute phase; and to confer a long-term functional recovery.
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http://dx.doi.org/10.1016/j.neuropharm.2020.108038DOI Listing
June 2020

Steroid profiles in quail brain and serum: Sex and regional differences and effects of castration with steroid replacement.

J Neuroendocrinol 2019 02 1;31(2):e12681. Epub 2019 Feb 1.

GIGA Neurosciences, University of Liège, Liège, Belgium.

Both systemic and local production contribute to the concentration of steroids measured in the brain. This idea was originally based on rodent studies and was later extended to other species, including humans and birds. In quail, a widely used model in behavioural neuroendocrinology, it was demonstrated that all enzymes needed to produce sex steroids from cholesterol are expressed and active in the brain, although the actual concentrations of steroids produced were never investigated. We carried out a steroid profiling in multiple brain regions and serum of sexually mature male and female quail by gas chromatography coupled with mass spectrometry. The concentrations of some steroids (eg, corticosterone, progesterone and testosterone) were in equilibrium between the brain and periphery, whereas other steroids (eg, pregnenolone (PREG), 5α/β-dihydroprogesterone and oestrogens) were more concentrated in the brain. In the brain regions investigated, PREG sulphate, progesterone and oestrogen concentrations were higher in the hypothalamus-preoptic area. Progesterone and its metabolites were more concentrated in the female than the male brain, whereas testosterone, its metabolites and dehydroepiandrosterone were more concentrated in males, suggesting that sex steroids present in quail brain mainly depend on their specific steroidogenic pathways in the ovaries and testes. However, the results of castration experiments suggested that sex steroids could also be produced in the brain independently of the peripheral source. Treatment with testosterone or oestradiol restored the concentrations of most androgens or oestrogens, respectively, although penetration of oestradiol in the brain appeared to be more limited. These studies illustrate the complex interaction between local brain synthesis and the supply from the periphery for the steroids present in the brain that are either directly active or represent the substrate of centrally located enzymes.
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http://dx.doi.org/10.1111/jne.12681DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6412023PMC
February 2019

Steroids in Stroke with Special Reference to Progesterone.

Cell Mol Neurobiol 2019 May 9;39(4):551-568. Epub 2018 Oct 9.

U1195 Inserm and University Paris-Sud and University Paris-Saclay, 80 rue du Général Leclerc, 94276, Le Kremlin-Bicêtre, France.

Both sex and steroid hormones are important to consider in human ischemic stroke and its experimental models. Stroke initiates a cascade of changes that lead to neural cell death, but also activates endogenous protective processes that counter the deleterious consequences of ischemia. Steroids may be part of these cerebroprotective processes. One option to provide cerebroprotection is to reinforce these intrinsic protective mechanisms. In the current review, we first summarize studies describing sex differences and the influence of steroid hormones in stroke. We then present and discuss our recent results concerning differential changes in endogenous steroid levels in the brains of male and female mice and the importance of progesterone receptors (PR) during the early phase after stroke. In the third part, we give an overview of experimental studies, including ours, that provide evidence for the pleiotropic beneficial effects of progesterone and its promising cerebroprotective potential in stroke. We also highlight the key role of PR signaling as well as potential additional mechanisms by which progesterone may provide cerebroprotection.
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http://dx.doi.org/10.1007/s10571-018-0627-0DOI Listing
May 2019

Abnormal steroidogenesis and aromatase activity in preeclampsia.

Placenta 2018 09 7;69:40-49. Epub 2018 Jul 7.

Department of Nephrology, Assistance Publique des Hôpitaux de Paris (APHP), Sorbonne University, Tenon Hospital, Paris, France. Electronic address:

Introduction: Estrogens and progesterone play critical roles in angiogenesis and vasodilation. Moreover, placental aromatase deficiency is detected in women with preeclampsia (PE) at delivery. We hypothesized that abnormal steroidogenesis occurs much earlier than typical PE diagnosis. Thus, we investigated whether the circulating steroid profile was already disturbed at 24-29 weeks of gestation in women with subsequent PE, and compared the profile with that of women with "placental" small gestational age (SGA) without PE.

Methods: We selected nulliparous women (n = 90) from the MOMA trial, including women with PE (n = 25), SGA (n = 25), and controls (NP; n = 40), for plasma steroid profiling by gas chromatography/mass spectrometry and to measure placental growth factor and soluble fms-like tyrosine kinase-1. Placental aromatase expression was evaluated in a new set of women.

Results: Compared with that of controls, the women with PE had a significantly lower estrone/androstenedione ratio, and exhibited a decreasing trend for estradiol and estrone levels. Lower estriol levels were observed in the SGA group compared to the NP group. Compared with that of controls, the women with PE and SGA had significantly higher levels of 20α-dihydroprogesterone (20α-DHP) and 20α-DHP/progesterone ratios. Pregnenolone sulfate levels were lower in the PE group than in the NP and SGA groups. Decreased expression of aromatase was observed in the PE group compared to the control group.

Discussion: Preeclampsia appears to be characterized by specific steroidogenesis dysregulation long before PE diagnosis, highlighting potential new biomarkers of PE.
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http://dx.doi.org/10.1016/j.placenta.2018.07.004DOI Listing
September 2018

Behavioral evidence for sex steroids hypersensitivity in castrated male canaries.

Horm Behav 2018 07 28;103:80-96. Epub 2018 Jun 28.

GIGA Neurosciences, University of Liege, Liège, Belgium. Electronic address:

In seasonally breeding songbirds such as canaries, singing behavior is predominantly under the control of testosterone and its metabolites. Short daylengths in the fall that break photorefractoriness are followed by increasing daylengths in spring that activate singing via both photoperiodic and hormonal mechanisms. However, we observed in a group of castrated male Fife fancy canaries maintained for a long duration under a short day photoperiod a large proportion of subjects that sang at high rates. This singing rate was not correlated with variation in the low circulating concentrations of testosterone. Treatment of these actively singing castrated male canaries with a combination of an aromatase inhibitor (ATD) and an androgen receptor blocker (flutamide) only marginally decreased this singing activity as compared to control untreated birds and did not affect various measures of song quality. The volumes of HVC and of the medial preoptic nucleus (POM) were also unaffected by these treatments but were relatively large and similar to volumes in testosterone-treated males. In contrast, peripheral androgen-sensitive structures such as the cloacal protuberance and syrinx mass were small, similar to what is observed in castrates. Together these data suggest that after a long-term steroid deprivation singing behavior can be activated by very low concentrations of testosterone. Singing normally depends on the activation by testosterone and its metabolites of multiple downstream neurochemical systems such as catecholamines, nonapeptides or opioids. These transmitter systems might become hypersensitive to steroid action after long term castration as they probably are at the end of winter during the annual cycle in seasonally breeding temperate zone species.
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http://dx.doi.org/10.1016/j.yhbeh.2018.06.004DOI Listing
July 2018

Intranasal administration of progesterone: A potential efficient route of delivery for cerebroprotection after acute brain injuries.

Neuropharmacology 2019 02 6;145(Pt B):283-291. Epub 2018 Jun 6.

M et P Pharma AG, Schynweg 7, P.O. Box 138, 6376, Emmetten, Switzerland; Nova Southeastern University, Fort Lauderdale, FL, 33314, USA.

Progesterone has been shown to be cerebroprotective in different experimental models of brain injuries and neurodegenerative diseases. The preclinical data provided great hope for its use in humans. The failure of Phase 3 clinical trials to demonstrate the cerebroprotective efficiency of progesterone in traumatic brain injury (TBI) patients emphasizes that different aspects of the design of both experimental and clinical studies should be reviewed and refined. One important aspect to consider is to test different routes of delivery of therapeutic agents. Several studies have shown that the intranasal delivery of drugs could be used in different experimental models of central nervous system diseases. In this review, we will summarize the pharmacokinetic characteristics and practical advantages of intranasal delivery of progesterone. A special emphasis will be placed on describing and discussing our recent findings showing that intranasal delivery of progesterone after transient focal cerebral ischemia: 1) improved motor functions; 2) reduced infarct volume, neuronal loss, blood brain barrier disruption; and 3) reduced brain mitochondrial dysfunctions. Our data suggest that intranasal delivery of progesterone is a potential efficient, safe and non-stressful mode of administration that warrants evaluation for cerebroprotection in patients with brain injuries. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".
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http://dx.doi.org/10.1016/j.neuropharm.2018.06.006DOI Listing
February 2019

Role of Sex Hormones on Brain Mitochondrial Function, with Special Reference to Aging and Neurodegenerative Diseases.

Front Aging Neurosci 2017 7;9:406. Epub 2017 Dec 7.

U1195 Inserm and University Paris-Sud and University Paris-Saclay, Le Kremlin-Bicêtre, France.

The mitochondria have a fundamental role in both cellular energy supply and oxidative stress regulation and are target of the effects of sex steroids, particularly the neuroprotective ones. Aging is associated with a decline in the levels of different steroid hormones, and this decrease may underline some neural dysfunctions. Besides, modifications in mitochondrial functions associated with aging processes are also well documented. In this review, we will discuss studies that describe the modifications of brain mitochondrial function and of steroid levels associated with physiological aging and with neurodegenerative diseases. A special emphasis will be placed on describing and discussing our recent findings concerning the concomitant study of mitochondrial function (oxidative phosphorylation, oxidative stress) and brain steroid levels in both young (3-month-old) and aged (20-month-old) male and female mice.
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http://dx.doi.org/10.3389/fnagi.2017.00406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5725410PMC
December 2017

Revisiting medial preoptic area plasticity induced in male mice by sexual experience.

Sci Rep 2017 12 19;7(1):17846. Epub 2017 Dec 19.

Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris - Seine; Institut de Biologie Paris Seine, 75005, Paris, France.

Sexual experience in male rodents, induced by a first exposure to a receptive female, improves efficiency of following copulations. In mice, the mechanisms supporting this improvement are poorly understood. We characterized molecular modifications of the mouse hypothalamic medial preoptic area (mPOA), the main integrative structure for male sexual behaviour, after a single mating event. This paradigm induced long-lasting behavioural improvements and mPOA morphological changes, evidenced by dendritic spine maturation and an increase in the acetylated and tri-methylated forms of histone H3. Ejaculation affected testosterone, progesterone and corticosterone levels in both naive and experienced mice, but sexual experience did not modify basal plasma or hypothalamic levels of steroids. In contrast to studies carried out in rats, no changes were observed, either in the nitrergic system, or in sex steroid receptor levels. However, levels of glutamate- and calcium-associated proteins, including PSD-95, calbindin and the GluN1 subunit of the NMDA receptor, were increased in sexually experienced male mice. The Iba-1 microglial marker was up-regulated in these animals suggesting multicellular interactions induced within the mPOA by sexual experience. In conclusion, plasticity mechanisms induced by sexual experience differ between rat and mouse, even if in both cases they converge to potentiation of the mPOA network.
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http://dx.doi.org/10.1038/s41598-017-18248-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5736590PMC
December 2017

Long-lasting masculinizing effects of postnatal androgens on myelin governed by the brain androgen receptor.

PLoS Genet 2017 Nov 6;13(11):e1007049. Epub 2017 Nov 6.

U1195 Inserm and Universities Paris-Sud and Paris-Saclay, 80 rue du Général Leclerc, Kremlin-Bicêtre, France.

The oligodendrocyte density is greater and myelin sheaths are thicker in the adult male mouse brain when compared with females. Here, we show that these sex differences emerge during the first 10 postnatal days, precisely at a stage when a late wave of oligodendrocyte progenitor cells arises and starts differentiating. Androgen levels, analyzed by gas chromatography/tandem-mass spectrometry, were higher in males than in females during this period. Treating male pups with flutamide, an androgen receptor (AR) antagonist, or female pups with 5α-dihydrotestosterone (5α-DHT), revealed the importance of postnatal androgens in masculinizing myelin and their persistent effect into adulthood. A key role of the brain AR in establishing the sexual phenotype of myelin was demonstrated by its conditional deletion. Our results uncover a new persistent effect of postnatal AR signaling, with implications for neurodevelopmental disorders and sex differences in multiple sclerosis.
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http://dx.doi.org/10.1371/journal.pgen.1007049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5690690PMC
November 2017

A Role of Endogenous Progesterone in Stroke Cerebroprotection Revealed by the Neural-Specific Deletion of Its Intracellular Receptors.

J Neurosci 2017 11 6;37(45):10998-11020. Epub 2017 Oct 6.

U1195 Inserm and University Paris-Sud and University Paris-Saclay, 94276 Kremlin-Bicêtre, France,

Treatment with progesterone protects the male and female brain against damage after middle cerebral artery occlusion (MCAO). However, in both sexes, the brain contains significant amounts of endogenous progesterone. It is not known whether endogenously produced progesterone enhances the resistance of the brain to ischemic insult. Here, we used steroid profiling by gas chromatography-tandem mass spectrometry (GC-MS/MS) for exploring adaptive and sex-specific changes in brain levels of progesterone and its metabolites after MCAO. We show that, in the male mouse brain, progesterone is mainly metabolized via 5α-reduction leading to 5α-dihydroprogesterone (5α-DHP), also a progesterone receptor (PR) agonist ligand in neural cells, then to 3α,5α-tetrahydroprogesterone (3α,5α-THP). In the female mouse brain, levels of 5α-DHP and 3α,5α-THP are lower and levels of 20α-DHP are higher than in males. After MCAO, levels of progesterone and 5α-DHP are upregulated rapidly to pregnancy-like levels in the male but not in the female brain. To assess whether endogenous progesterone and 5α-DHP contribute to the resistance of neural cells to ischemic damage, we inactivated PR selectively in the CNS. Deletion of PR in the brain reduced its resistance to MCAO, resulting in increased infarct volumes and neurological deficits in both sexes. Importantly, endogenous PR ligands continue to protect the brain of aging mice. These results uncover the unexpected importance of endogenous progesterone and its metabolites in cerebroprotection. They also reveal that the female reproductive hormone progesterone is an endogenous cerebroprotective neurosteroid in both sexes. The brain responds to injury with protective signaling and has a remarkable capacity to protect itself. We show here that, in response to ischemic stroke, levels of progesterone and its neuroactive metabolite 5α-dihydroprogesterone are upregulated rapidly in the male mouse brain but not in the female brain. An important role of endogenous progesterone in cerebroprotection was demonstrated by the conditional inactivation of its receptor in neural cells. These results show the importance of endogenous progesterone, its metabolites, and neural progesterone receptors in acute cerebroprotection after stroke. This new concept could be exploited therapeutically by taking into account the progesterone status of patients and by supplementing and reinforcing endogenous progesterone signaling for attaining its full cerebroprotective potential.
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http://dx.doi.org/10.1523/JNEUROSCI.3874-16.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6596486PMC
November 2017

Differential effects of the 18-kDa translocator protein (TSPO) ligand etifoxine on steroidogenesis in rat brain, plasma and steroidogenic glands: Pharmacodynamic studies.

Psychoneuroendocrinology 2017 Sep 3;83:122-134. Epub 2017 Jun 3.

U1195 INSERM and Université Paris Sud and Université Paris-Saclay, 80 rue du Général Leclerc, 94276 Le Kremlin-Bicêtre, France. Electronic address:

Etifoxine is indicated in humans for treating anxiety. In rodents, besides its anxiolytic-like properties, it has recently shown neuroprotective and neuroregenerative activities. It acts by enhancing GABA receptor function and by stimulating acute steroid biosynthesis via the activation of the 18-kDa translocator protein. However, the regulatory action of etifoxine on steroid production is not well characterized. In this work, we performed dose-response, acute and chronic time-course experiments on the effects of intraperitoneal injections of etifoxine on steroid levels in adult male rat brain and plasma analyzed by gas chromatography-mass spectrometry. Concentrations of pregnenolone, progesterone and its 5α-reduced metabolites were significantly increased in both tissues in response to 25 and 50mg/kg of etifoxine, as compared with vehicle controls, and reached maximal values at 0.5-1h post-injection. Daily injections of etifoxine (50mg/kg, 15days) kept them increased at day 15. Comparisons between steroidogenic tissues revealed that 1h after 50mg/kg of etifoxine treatment, levels of pregnenolone, progesterone and corticosterone were highest in adrenal glands and markedly increased together with their reduced metabolites. They were also increased by etifoxine in brain and plasma, but not in testis except for corticosterone and its metabolites. In contrast, testosterone level was significantly decreased in testis while with its 5α-reduced metabolites, it was unchanged in brain. Results demonstrate that the modulation of steroid concentrations by etifoxine is dependent on the type of steroid and on the steroidogenic organ. They further suggest that adrenal steroids upregulated by etifoxine make an important contribution to the steroids present in brain. This work provides a precise and complete view of steroids regulated by etifoxine that could be useful in therapeutic research.
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http://dx.doi.org/10.1016/j.psyneuen.2017.05.022DOI Listing
September 2017

From Pregnancy to Preeclampsia: A Key Role for Estrogens.

Endocr Rev 2017 04;38(2):123-144

University of Pierre and Marie Curie, Sorbonne University, Paris 06, 75005 Paris, France.

Preeclampsia (PE) results in placental dysfunction and is one of the primary causes of maternal and fetal mortality and morbidity. During pregnancy, estrogen is produced primarily in the placenta by conversion of androgen precursors originating from maternal and fetal adrenal glands. These processes lead to increased plasma estrogen concentrations compared with levels in nonpregnant women. Aberrant production of estrogens could play a key role in PE symptoms because they are exclusively produced by the placenta and they promote angiogenesis and vasodilation. Previous assessments of estrogen synthesis during PE yielded conflicting results, possibly because of the lack of specificity of the assays. However, with the introduction of reliable analytical protocols using liquid chromatography/mass spectrometry or gas chromatography/mass spectrometry, more recent studies suggest a marked decrease in estradiol levels in PE. The aim of this review is to summarize current knowledge of estrogen synthesis, regulation in the placenta, and biological effects during pregnancy and PE. Moreover, this review highlights the links among the occurrence of PE, estrogen biosynthesis, angiogenic factors, and cardiovascular risk factors. A close link between estrogen dysregulation and PE occurrence might validate estrogen levels as a biomarker but could also reveal a potential approach for prevention or cure of PE.
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http://dx.doi.org/10.1210/er.2016-1065DOI Listing
April 2017

Nestorone® as a Novel Progestin for Nonoral Contraception: Structure-Activity Relationships and Brain Metabolism Studies.

Endocrinology 2017 01;158(1):170-182

Population Council, Center for Biomedical Research, New York, New York 10065.

Nestorone® (NES) is a potent nonandrogenic progestin being developed for contraception. NES is a synthetic progestin that may possess neuroprotective and myelin regenerative potential as added health benefits. In receptor transactivation experiments, NES displayed greater potency than progesterone to transactivate the human progesterone receptor (PR). This was confirmed by docking experiments where NES adopts the same docking position within the PR ligand-binding domain (LBD) as progesterone and forms additional stabilizing contacts between 17α-acetoxy and 16-methylene groups and PR LBD, supporting its higher potency than progesterone. The analog 13-ethyl NES also establishes similar contacts as NES with Met909, leading to comparable potency as NES. In contrast, NES is not stabilized within the human androgen receptor LBD, leading to negligible androgen receptor transactivation. Because progesterone acts in the brain by both PR binding and indirectly via binding of the metabolite allopregnanolone to γ-aminobutyric acid type A receptor (GABAAR), we investigated if NES is metabolized to 3α, 5α-tetrahydronestorone (3α, 5α-THNES) in the brain and if this metabolite could interact with GABAAR. In female mice, low concentrations of reduced NES metabolites were identified by gas chromatography/mass spectrometry in both plasma and brain. Electrophysiological studies showed that 3α, 5α-THNES exhibited only limited activity to enhance GABAAR-evoked responses with WSS-1 cells and did not modulate synaptic GABAARs of mouse cortical neurons. Thus, the inability of reduced metabolite of NES (3α, 5α-THNES) to activate GABAAR suggests that the neuroprotective and myelin regenerative effects of NES are mediated via PR binding and not via its interaction with the GABAAR.
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http://dx.doi.org/10.1210/en.2016-1426DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5412978PMC
January 2017

Steroid Profiling in Male Wobbler Mouse, a Model of Amyotrophic Lateral Sclerosis.

Endocrinology 2016 Nov 29;157(11):4446-4460. Epub 2016 Aug 29.

Unité 1195 INSERM and University Paris-Sud and University Paris Saclay (P.L., A.P., F.A., A.C., M.S., R.G.), 94276 Kremlin-Bicêtre, France; Laboratory of Neuroendocrine Biochemistry (M.C.G.-D., M.M., A.F.D.N.) and Laboratory of Neuroendocrinology (N.P.D.G.), Instituto de Biologia y Medicina Experimental-Consejo Nacional de Investigaciones Cientificas y Técnicas, 1428 Buenos Aires, Argentina; and Departamento de Ciencias Fisiológicas (M.C.G.-D.), Facultad de Medicina, Universidad de Buenos Aires, 1121 Buenos Aires, Argentina.

The Wobbler mouse is an animal model for human motoneuron diseases, especially amyotrophic lateral sclerosis (ALS), used in the investigation of both pathology and therapeutic treatment. ALS is a fatal neurodegenerative disease, characterized by the selective and progressive death of motoneurons, leading to progressive paralysis. Previous limited studies have reported steroidal hormone dysregulation in Wobbler mouse and in ALS patients, suggesting endocrine dysfunctions which may be involved in the pathogenesis of the disease. In this study, we established a steroid profiling in brain, spinal cord, plasma, adrenal glands, and testes in 2-month-old male Wobbler mice and their littermates by gas chromatography coupled to mass spectrometry. Our results show in Wobbler mice the following: 1) a marked up-regulation of corticosterone levels in adrenal glands, plasma, spinal cord regions (cervical, thoracic, lumbar) and brain; 2) a strong decrease in T levels in the testis, plasma, spinal cord, and brain; and 3) increased levels of progesterone and especially of its reduced metabolites 5α-dihydroprogesterone, allopregnanolone, and 20α-dihydroprogesterone in the brain, spinal cord, and adrenal glands. Furthermore, Wobbler mice showed a hypothalamic-pituitary-gonadal hypoactivity. Interestingly, plasma concentrations of corticosterone and T correlate well with their respective levels in cervical spinal cord in both control and Wobbler mice. T down-regulation is probably the consequence of adrenal hyperactivity, and the up-regulation of progesterone and its reduced metabolites may correspond to an endogenous protective mechanism in response to motoneuron degeneration. Our findings suggest that increased levels of corticosterone and decreased levels of T in plasma could be a signature of motoneuron degeneration.
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http://dx.doi.org/10.1210/en.2016-1244DOI Listing
November 2016

Steroid hormones in bovine oviductal fluid during the estrous cycle.

Theriogenology 2016 Oct 7;86(6):1409-1420. Epub 2016 May 7.

PRC, INRA, CNRS, IFCE, Université de Tours, Nouzilly, France; UFR Sciences et Techniques, Université François Rabelais de Tours, Tours, France. Electronic address:

Ovarian steroid hormones are major regulators of the physiology of the oviduct and reproductive events occurring within the oviduct. To establish a whole steroid profiling of the bovine oviductal fluid (OF) during the estrous cycle, contralateral and ipsilateral (to the corpus luteum or preovulatory follicle) oviducts were classified into four stages of the estrous cycle (n = 18-27 cows per stage): postovulatory (Post-ov), mid-luteal (Mid-lut), late luteal (Late-lut), and preovulatory on the basis of the ovarian morphology and intrafollicular steroid concentrations. Steroids were extracted from pools of 150 to 200 μL OF (three to 10 cows per pool; three to four pools per "stage × side" group), purified, fractioned by high-performance liquid chromatography, and analyzed by gas chromatography coupled with tandem mass spectrometry. The concentrations of progesterone (P4) in ipsilateral OF increased from Post-ov (56.9 ± 13.4 ng/mL) to Mid-lut (120.3 ± 34.3 ng/mL), then decreased from Late-lut (76.7 ± 1.8 ng/mL) to Pre-ov (6.3 ± 1.7 ng/mL), and were four to 16 times higher than in contralateral OF. Most P4 metabolites followed similar patterns of variation. Concentrations of 17beta-estradiol (E2) were significantly higher at Pre-ov (290.5 ± 63.2 pg/mL) compared with all other stages (<118.3 pg/mL), with no difference regarding the side of ovulation. Concentrations of androstenedione displayed a pattern similar to that of E2, whereas other androgens, estrone, and corticoids did not vary between stages or sides. In conclusion, a highly concentrated and fluctuating hormonal environment was evidenced in the bovine OF. These results could be useful to improve media for IVF, embryo development, and culture of oviductal cells.
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http://dx.doi.org/10.1016/j.theriogenology.2016.04.086DOI Listing
October 2016

Differential efficacy of the TSPO ligands etifoxine and XBD-173 in two rodent models of Multiple Sclerosis.

Neuropharmacology 2016 09 30;108:229-37. Epub 2016 Mar 30.

EMD Serono Research and Development Institute, Billerica, MA 01821, USA. Electronic address:

Neurosteroids such as progesterone and allopregnanolone have been shown to exert neuroprotective effects under a variety of pathological or insult conditions, and there is evidence that the neurosteroid system is perturbed in Multiple Sclerosis (MS) patients. Neurosteroids are synthesized in the central nervous system (CNS) through a series of metabolic transformations, beginning with a rate-limiting step of cholesterol transport through the outer mitochondrial membrane via the transporter translocator protein (TSPO). We examined the effects of etifoxine and XBD-173, two different brain penetrant TSPO agonists, for their ability to ameliorate clinical signs in two different experimental autoimmune encephalitis (EAE) models. Etifoxine, as previously reported, was efficacious in EAE, while XBD-173 was not. Surprisingly, XBD-173, but not etifoxine elevated relevant neurosteroids in brain of female rats and differed in its ability to exert anti-inflammatory and direct neuroprotective effects in vitro as compared to etifoxine. We conclude that the neurosteroid elevations produced in brain by XBD-173 are not sufficient to ameliorate EAE and suggest that etifoxine may have additional mechanisms of action that provide therapeutic benefit in this model system.
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http://dx.doi.org/10.1016/j.neuropharm.2016.03.053DOI Listing
September 2016

Mass spectrometric analysis of steroids: all that glitters is not gold.

Expert Rev Endocrinol Metab 2015 Sep 7;10(5):463-465. Epub 2015 Jul 7.

b 2 Neuroprotective, Neuroregenerative and Remyelinating Small Molecules, U1195 Inserm and University Paris-Sud, 80 rue du Général Leclerc, 94276 Kremlin-Bicêtre, France.

Steroid hormones are small molecules (MW around 300 Da) characterized by a large range of polarity and their analysis has always presented a serious challenge. Persistent problems with the specificity of conventional immunological methods are the cause of inconsistent results in the literature, a particularly problematic situation for healthcare decisions. At present, mass spectrometric methods have become the gold standard for accurate steroid profiling, and their advent will require the re-analysis of previously published data. However, it is a common misconception to consider the use of theses sophisticated technologies as a guarantee for accurate measures. Steroid analysis, especially in nervous tissues, indeed requires well-validated purification and separation steps before mass spectrometry, only then will mass spectrometric analysis be the absolute reference methodology.
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http://dx.doi.org/10.1586/17446651.2015.1063997DOI Listing
September 2015

Analytical challenges for measuring steroid responses to stress, neurodegeneration and injury in the central nervous system.

Steroids 2015 Nov 21;103:42-57. Epub 2015 Aug 21.

U1195 Inserm and University Paris-Sud, Kremlin-Bicêtre, France.

Levels of steroids in the adult central nervous system (CNS) show marked changes in response to stress, degenerative disorders and injury. However, their analysis in complex matrices such as fatty brain and spinal cord tissues, and even in plasma, requires accurate and precise analytical methods. Radioimmunoassays (RIA) and enzyme-linked immunosorbent assays, even with prepurification steps, do not provide sufficient specificity, and they are at the origin of many inconsistent results in the literature. The analysis of steroids by mass spectrometric methods has become the gold standard for accurate and sensitive steroid analysis. However, these technologies involve multiple purification steps prone to errors, and they only provide accurate reference values when combined with careful sample workup. In addition, the interpretation of changes in CNS steroid levels is not an easy task because of their multiple sources: the endocrine glands and the local synthesis by neural cells. In the CNS, decreased steroid levels may reflect alterations of their biosynthesis, as observed in the case of chronic stress, post-traumatic stress disorders or depressive episodes. In such cases, return to normalization by administering exogenous hormones or by stimulating their endogenous production may have beneficial effects. On the other hand, increases in CNS steroids in response to acute stress, degenerative processes or injury may be part of endogenous protective or rescue programs, contributing to the resistance of neural cells to stress and insults. The aim of this review is to encourage a more critical reading of the literature reporting steroid measures, and to draw attention to the absolute need for well-validated methods. We discuss reported findings concerning changing steroid levels in the nervous system by insisting on methodological issues. An important message is that even recent mass spectrometric methods have their limits, and they only become reliable tools if combined with careful sample preparation.
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http://dx.doi.org/10.1016/j.steroids.2015.08.013DOI Listing
November 2015

Intranasal delivery of progesterone after transient ischemic stroke decreases mortality and provides neuroprotection.

Neuropharmacology 2015 Oct 14;97:394-403. Epub 2015 Jun 14.

U1195 Inserm and University Paris-Sud, 80 rue du Général Leclerc, 94276 Kremlin-Bicêtre, France. Electronic address:

Progesterone is a potential neuroprotective agent for cerebral stroke. One of the STAIR's recommendations is to test different routes of delivery of therapeutic agents. Here, we investigated the neuroprotective efficacy of intranasal delivery of progesterone in oleogel. Male mice were subjected to transient middle cerebral occlusion (MCAO) for 1 h. Mice received intranasal or intraperitoneal administrations of progesterone (8 mg/kg) at 1, 6, and 24 h post-MCAO. Plasma and brain levels of steroids were measured by gas chromatography-mass spectrometry 2 and 24 h after the last administration of progesterone. Behavioral and histopathological analyzes were performed at 48 h post-MCAO. For blood-brain barrier (BBB) permeability analysis, mice received one intranasal administration of progesterone or placebo at reperfusion and Evans Blue and sodium fluorescein extravasations were assessed at 4 h post-MCAO. Two hours after its nasal administration, progesterone reached elevated levels in brain and plasma and was bioconverted to its 5α-reduced metabolites and to 20α-dihydroprogesterone. However, brain levels of progesterone and its metabolites were about half those measured after intraperitoneal injections, whereas levels of 11-deoxycorticosterone and corticosterone were 5-times lower. In contrast, after 24 h, higher levels of progesterone were measured in brain and plasma after intranasal than after intraperitoneal delivery. Intranasal progesterone decreased the mortality rate, improved motor functions, reduced infarct, attenuated neuronal loss, and decreased the early BBB disruption. This study demonstrates a good bioavailability, a prolonged absorption and a good neuroprotective efficacy of intranasal delivery of progesterone, thus potentially offering an efficient, safe, non-stressful and very easy mode of administration in stroke patients.
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http://dx.doi.org/10.1016/j.neuropharm.2015.06.002DOI Listing
October 2015

Effect of Sex Differences on Brain Mitochondrial Function and Its Suppression by Ovariectomy and in Aged Mice.

Endocrinology 2015 Aug 3;156(8):2893-904. Epub 2015 Jun 3.

U1195 Inserm and University Paris-Sud (P.G., P.L., A.P., M.S., R.G.), 94276 Le Kremlin-Bicêtre Cedex, France; and Biochemistry Laboratory (P.G., S.S., P.T., A.S.), Bicêtre Hospital, Assistance Publique - Hôpitaux de Paris, University Paris-Sud, 94275 Le Kremlin-Bicêtre Cedex, France.

Sex steroids regulate brain function in both normal and pathological states. Mitochondria are an essential target of steroids, as demonstrated by the experimental administration of 17β-estradiol or progesterone (PROG) to ovariectomized female rodents, but the influence of endogenous sex steroids remains understudied. To address this issue, mitochondrial oxidative stress, the oxidative phosphorylation system, and brain steroid levels were analyzed under 3 different experimental sets of endocrine conditions. The first set was designed to study steroid-mediated sex differences in young male and female mice, intact and after gonadectomy. The second set concerned young female mice at 3 time points of the estrous cycle in order to analyze the influence of transient variations in steroid levels. The third set involved the evaluation of the effects of a permanent decrease in gonadal steroids in aged male and female mice. Our results show that young adult females have lower oxidative stress and a higher reduced nicotinamide adenine dinucleotide (NADH)-linked respiration rate, which is related to a higher pyruvate dehydrogenase complex activity as compared with young adult males. This sex difference did not depend on phases of the estrous cycle, was suppressed by ovariectomy but not by orchidectomy, and no longer existed in aged mice. Concomitant analysis of brain steroids showed that pregnenolone and PROG brain levels were higher in females during the reproductive period than in males and decreased with aging in females. These findings suggest that the major male/female differences in brain pregnenolone and PROG levels may contribute to the sex differences observed in brain mitochondrial function.
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http://dx.doi.org/10.1210/en.2014-1913DOI Listing
August 2015

Liver X receptors alpha and beta promote myelination and remyelination in the cerebellum.

Proc Natl Acad Sci U S A 2015 Jun 28;112(24):7587-92. Epub 2015 May 28.

UMR-S 1124 INSERM, Paris Descartes University, Sorbonne Paris Cité University, Centre Interdisciplinaire Chimie Biologie-Paris (FR 3567, CNRS), 75270 Paris Cedex 6, France;

The identification of new pathways governing myelination provides innovative avenues for remyelination. Liver X receptors (LXRs) α and β are nuclear receptors activated by oxysterols that originated from the oxidation of cholesterol. They are crucial for cholesterol homeostasis, a major lipid constituent of myelin sheaths that are formed by oligodendrocytes. However, the role of LXRs in myelin generation and maintenance is poorly understood. Here, we show that LXRs are involved in myelination and remyelination processes. LXRs and their ligands are present in oligodendrocytes. We found that mice invalidated for LXRs exhibit altered motor coordination and spatial learning, thinner myelin sheaths, and reduced myelin gene expression. Conversely, activation of LXRs by either 25-hydroxycholesterol or synthetic TO901317 stimulates myelin gene expression at the promoter, mRNA, and protein levels, directly implicating LXRα/β in the transcriptional control of myelin gene expression. Interestingly, activation of LXRs also promotes oligodendroglial cell maturation and remyelination after lysolecithin-induced demyelination of organotypic cerebellar slice cultures. Together, our findings represent a conceptual advance in the transcriptional control of myelin gene expression and strongly support a new role of LXRs as positive modulators in central (re)myelination processes.
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http://dx.doi.org/10.1073/pnas.1424951112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4475952PMC
June 2015

Progesterone and nestorone promote myelin regeneration in chronic demyelinating lesions of corpus callosum and cerebral cortex.

Glia 2015 Jan 4;63(1):104-17. Epub 2014 Aug 4.

UMR 788 Inserm and University Paris-Sud, 94276, Kremlin-Bicêtre, France.

Multiple Sclerosis affects mainly women and consists in intermittent or chronic damages to the myelin sheaths, focal inflammation, and axonal degeneration. Current therapies are limited to immunomodulators and antiinflammatory drugs, but there is no efficient treatment for stimulating the endogenous capacity of myelin repair. Progesterone and synthetic progestins have been shown in animal models of demyelination to attenuate myelin loss, reduce clinical symptoms severity, modulate inflammatory responses and partially reverse the age-dependent decline in remyelination. Moreover, progesterone has been demonstrated to promote myelin formation in organotypic cultures of cerebellar slices. In the present study, we show that progesterone and the synthetic 19-nor-progesterone derivative Nestorone® promote the repair of severe chronic demyelinating lesions induced by feeding cuprizone to female mice for up to 12 weeks. Progesterone and Nestorone increase the density of NG2(+) oligodendrocyte progenitor cells and CA II(+) mature oligodendrocytes and enhance the formation of myelin basic protein (MBP)- and proteolipid protein (PLP)-immunoreactive myelin. However, while demyelination in response to cuprizone was less marked in corpus callosum than in cerebral cortex, remyelination appeared earlier in the former. The remyelinating effect of progesterone was progesterone receptor (PR)-dependent, as it was absent in PR-knockout mice. Progesterone and Nestorone also decreased (but did not suppress) neuroinflammatory responses, specifically astrocyte and microglial cell activation. Therefore, some progestogens are promising therapeutic candidates for promoting the regeneration of myelin.
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http://dx.doi.org/10.1002/glia.22736DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4237628PMC
January 2015

Mutation of the palmitoylation site of estrogen receptor α in vivo reveals tissue-specific roles for membrane versus nuclear actions.

Proc Natl Acad Sci U S A 2014 Jan 26;111(2):E283-90. Epub 2013 Dec 26.

Institut National de la Santé et de la Recherche Médicale U1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université de Toulouse, 31 432 Toulouse Cedex 4, France.

Estrogen receptor alpha (ERα) activation functions AF-1 and AF-2 classically mediate gene transcription in response to estradiol (E2). A fraction of ERα is targeted to plasma membrane and elicits membrane-initiated steroid signaling (MISS), but the physiological roles of MISS in vivo are poorly understood. We therefore generated a mouse with a point mutation of the palmitoylation site of ERα (C451A-ERα) to obtain membrane-specific loss of function of ERα. The abrogation of membrane localization of ERα in vivo was confirmed in primary hepatocytes, and it resulted in female infertility with abnormal ovaries lacking corpora lutea and increase in luteinizing hormone levels. In contrast, E2 action in the uterus was preserved in C451A-ERα mice and endometrial epithelial proliferation was similar to wild type. However, E2 vascular actions such as rapid dilatation, acceleration of endothelial repair, and endothelial NO synthase phosphorylation were abrogated in C451A-ERα mice. A complementary mutant mouse lacking the transactivation function AF-2 of ERα (ERα-AF2(0)) provided selective loss of function of nuclear ERα actions. In ERα-AF2(0), the acceleration of endothelial repair in response to estrogen-dendrimer conjugate, which is a membrane-selective ER ligand, was unaltered, demonstrating integrity of MISS actions. In genome-wide analysis of uterine gene expression, the vast majority of E2-dependent gene regulation was abrogated in ERα-AF2(0), whereas in C451A-ERα it was nearly fully preserved, indicating that membrane-to-nuclear receptor cross-talk in vivo is modest in the uterus. Thus, this work genetically segregated membrane versus nuclear actions of a steroid hormone receptor and demonstrated their in vivo tissue-specific roles.
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http://dx.doi.org/10.1073/pnas.1322057111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3896153PMC
January 2014

Prevention of obesity and insulin resistance by estrogens requires ERα activation function-2 (ERαAF-2), whereas ERαAF-1 is dispensable.

Diabetes 2013 Dec 31;62(12):4098-108. Epub 2013 Jul 31.

INSERM U1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III, Toulouse, France.

The beneficial metabolic actions of estrogen-based therapies are mainly mediated by estrogen receptor α (ERα), a nuclear receptor that regulates gene transcription through two activation functions (AFs): AF-1 and AF-2. Using mouse models deleted electively for ERαAF-1 (ERαAF-1°) or ERαAF-2 (ERαAF-2°), we determined their respective roles in the actions of estrogens on body composition and glucose homeostasis in response to either a normal diet or a high-fat diet (HFD). ERαAF-2° males and females developed accelerated weight gain, massive adiposity, severe insulin resistance, and glucose intolerance--quite reminiscent of the phenotype observed in mice deleted for the entire ERα protein (ERα(-/-)). In striking contrast, ERαAF-1° and wild-type (wt) mice shared a similar metabolic phenotype. Accordingly, 17β-estradiol administration regulated key metabolic genes in insulin-sensitive tissues and conferred a strong protection against HFD-induced metabolic disturbances in wt and ERαAF-1° ovariectomized mice, whereas these actions were totally abrogated in ERαAF-2° and ERα(-/-) mice. Thus, whereas both AFs have been previously shown to contribute to endometrial and breast cancer cell proliferation, the protective effect of estrogens against obesity and insulin resistance depends on ERαAF-2 but not ERαAF-1, thereby delineating new options for selective modulation of ERα.
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http://dx.doi.org/10.2337/db13-0282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3837069PMC
December 2013

Neuroprotection by steroids after neurotrauma in organotypic spinal cord cultures: a key role for progesterone receptors and steroidal modulators of GABA(A) receptors.

Neuropharmacology 2013 Aug 28;71:46-55. Epub 2013 Mar 28.

UMR 788, Inserm and University Paris-Sud., 80 rue du Général Leclerc, 94276 Kremlin-Bicêtre, France.

Progesterone is neuroprotective after spinal cord injury, however its mechanism of action remains unexplored. Here we used organotypic spinal cord slice cultures from 3 weeks-old mice to evaluate the mechanisms of neuroprotection by progesterone and its 5α-reduced metabolites. In vitro spinal cord injury, using a weight drop model, induced a decrease in the number of motoneurons. This was correlated with an increase in the number of dying cells (PI⁺ cells) and in LDH release. Addition of 10 μM of progesterone, 5α-dihydroprogesterone (5α-DHP) or allopregnanolone (3α, 5α-tetrahydroprogesterone) to the medium at the time of injury rescued the spinal cord slices from the effects of damage. Progesterone prevented membrane cell damage, motoneuron loss and cell death. These effects were not due to its bioconversion to 5α-DHP nor to allopregnanolone, as supported by the finasteride, an inhibitor of 5α-reductase enzymes, and by the absence of 5α-reduced progesterone metabolites in the slices analyzed by gas chromatography-mass spectrometry. The neuroprotective effects of progesterone required PR as they could not be observed in slices from homozygous knockout PR(-/-) mice. Allopregnanolone treatment was also neuroprotective. Its effects were not due to its bioconversion back to 5α-DHP, which can activate gene transcription via PR, because they were still observed in slices from knockout PR(-/-) mice. Allopregnanolone effects involved GABA(A) receptors, as they were inhibited by the selective GABA(A) receptor antagonist Gabazine, in both PR(+/+) and PR(-/-) mice. Altogether, these findings identify both PR and GABA(A) receptors as important targets for neuroprotection by progestagens after spinal cord injury.
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http://dx.doi.org/10.1016/j.neuropharm.2013.03.010DOI Listing
August 2013

Differential regulation of Wnt/beta-catenin signaling by Liver X Receptors in Schwann cells and oligodendrocytes.

Biochem Pharmacol 2013 Jul 13;86(1):106-14. Epub 2013 Mar 13.

University Paris Descartes, UMR 8194 CNRS, 45 rue des Saints-Pères, 75270, Paris Cedex 6, France.

Oxysterols are reactive molecules generated by the oxidation of cholesterol. Their implication in cholesterol homeostasis and in the progression of neurodegenerative disorders is well known. Here, we study the role of oxysterols and their nuclear receptors, Liver X Receptor (LXR), in myelinating glial cells of the central and peripheral nervous systems. First, we show by gas chromatography/mass spectrometry that the brain, sciatic nerve, oligodendrocytes and Schwann cells contain 24(S)-hydroxycholesterol, 25-hydroxycholesterol (25-OH) and 27-hydroxycholesterol, and they express their biosynthetic enzymes. We observed a differential effect of 25-OH toward myelin genes (MPZ and PMP22) expression: 25-OH inhibits MPZ and PMP22 in Schwann cell line but not in oligodendrocyte cell line. Importantly, the invalidation of LXR in mice enhanced MPZ and PMP22 transcripts expression in the sciatic nerve, but inhibited their expression in the brain. We have previously reported that Wnt signaling pathway is crucial for myelin gene expression. We show that the transcripts of Wnt components (Disheveled, TCF3, beta-catenin) are strongly repressed by oxysterols in Schwann cells but are activated in oligodendrocytes. Furthermore, we show by immunofluorescent labeling that beta-catenin is re-localized on the level of the Golgi apparatus of Schwann cells after incubation with 25-OH. We did not observe such an unusual localization of beta-catenin in oligodendrocytes. Our findings reveal a complex cross-talk between LXR and Wnt/beta-catenin pathway in myelinating glial cells.
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http://dx.doi.org/10.1016/j.bcp.2013.02.036DOI Listing
July 2013