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1.
Int J Mol Sci ; 24(3)2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36768796

RESUMO

The 18 kDa translocator protein (TSPO/PBR) is a multifunctional evolutionary highly conserved outer mitochondrial membrane protein. Decades of research has reported an obligatory role of TSPO/PBR in both mitochondrial cholesterol transport and, thus, steroid production. However, the strict dependency of steroidogenesis on TSPO/PBR has remained controversial. The aim of this study was to provide insight into the steroid profile in complete C57BL/6-Tspotm1GuWu(GuwiyangWurra)-knockout male mice (TSPO-KO) under basal conditions. The steroidome in the brain, adrenal glands, testes and plasma was measured by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). We found that steroids present in wild-type (WT) mice were also detected in TSPO-KO mice, including pregnenolone (PREG), progestogens, mineralo-glucocorticosteroids and androgens. The concentrations of PREG and most metabolites were similar between genotypes, except a significant decrease in the levels of the 5α-reduced metabolites of progesterone (PROG) in adrenal glands and plasma and of the 5α-reduced metabolites of corticosterone (B) in plasma in TSPO-KO compared to WT animals, suggesting other regulatory functions for the TSPO/PBR. The expression levels of the voltage-dependent anion-selective channel (VDAC-1), CYP11A1 and 5α-reductase were not significantly different between both groups. Thus, the complete deletion of the tspo gene in male mice does not impair de novo steroidogenesis in vivo.


Assuntos
Receptores de GABA , Espectrometria de Massas em Tandem , Masculino , Camundongos , Animais , Receptores de GABA/genética , Receptores de GABA/metabolismo , Camundongos Knockout , Camundongos Endogâmicos C57BL , Esteroides , Proteínas de Transporte , Pregnenolona
2.
Autophagy ; 19(2): 660-677, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-35867714

RESUMO

Synapses represent an important target of Alzheimer disease (AD), and alterations of their excitability are among the earliest changes associated with AD development. Synaptic activation has been shown to be protective in models of AD, and deep brain stimulation (DBS), a surgical strategy that modulates neuronal activity to treat neurological and psychiatric disorders, produced positive effects in AD patients. However, the molecular mechanisms underlying the protective role(s) of brain stimulation are still elusive. We have previously demonstrated that induction of synaptic activity exerts protection in mouse models of AD and frontotemporal dementia (FTD) by enhancing the macroautophagy/autophagy flux and lysosomal degradation of pathological MAPT/Tau. We now provide evidence that TFEB (transcription factor EB), a master regulator of lysosomal biogenesis and autophagy, is a key mediator of this cellular response. In cultured primary neurons from FTD-transgenic mice, synaptic stimulation inhibits MTORC1 signaling, thus promoting nuclear translocation of TFEB, which, in turn, induces clearance of MAPT/Tau oligomers. Conversely, synaptic activation fails to promote clearance of toxic MAPT/Tau in neurons expressing constitutively active RRAG GTPases, which sequester TFEB in the cytosol, or upon TFEB depletion. Activation of TFEB is also confirmed in vivo in DBS-stimulated AD mice. We also demonstrate that DBS reduces pathological MAPT/Tau and promotes neuroprotection in Parkinson disease patients with tauopathy. Altogether our findings indicate that stimulation of synaptic activity promotes TFEB-mediated clearance of pathological MAPT/Tau. This mechanism, underlying the protective effect of DBS, provides encouraging support for the use of synaptic stimulation as a therapeutic treatment against tauopathies.Abbreviations: 3xTg-AD: triple transgenic AD mice; AD: Alzheimer disease; CSA: cyclosporine A; DBS: deep brain stimulation; DIV: days in vitro; EC: entorhinal cortex; FTD: frontotemporal dementia; gLTP: glycine-induced long-term potentiation; GPi: internal segment of the globus pallidus; PD: Parkinson disease; STN: subthalamic nucleus; TFEB: transcription factor EB.


Assuntos
Doença de Alzheimer , Demência Frontotemporal , Doença de Parkinson , Tauopatias , Camundongos , Animais , Doença de Alzheimer/metabolismo , Demência Frontotemporal/metabolismo , Doença de Parkinson/metabolismo , Autofagia , Tauopatias/metabolismo , Camundongos Transgênicos , Lisossomos/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Proteínas tau/metabolismo
3.
Biochem J ; 479(13): 1455-1466, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35819398

RESUMO

Translocator protein (TSPO, 18 kDa), formerly known as peripheral benzodiazepine receptor, is an evolutionary well-conserved protein located on the outer mitochondrial membrane. TSPO is involved in a variety of fundamental physiological functions and cellular processes. Its expression levels are regulated under many pathological conditions, therefore, TSPO has been proposed as a tool for diagnostic imaging and an attractive therapeutic drug target in the nervous system. Several synthetic TSPO ligands have thus been explored as agonists and antagonists for innovative treatments as neuroprotective and regenerative agents. In this review, we provide state-of-the-art knowledge of TSPO functions in the brain and peripheral nervous system. Particular emphasis is placed on its contribution to important physiological functions such as mitochondrial homeostasis, energy metabolism and steroidogenesis. We also report how it is involved in neuroinflammation, brain injury and diseases of the nervous system.


Assuntos
Proteínas Mitocondriais , Receptores de GABA , Encéfalo/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Receptores de GABA/genética , Receptores de GABA/metabolismo
4.
CNS Neurosci Ther ; 27(4): 464-469, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33369182

RESUMO

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


Assuntos
Doenças Desmielinizantes/tratamento farmacológico , Modelos Animais de Doenças , Bainha de Mielina/efeitos dos fármacos , Norprogesteronas/uso terapêutico , Remielinização/efeitos dos fármacos , Animais , Doenças Desmielinizantes/metabolismo , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Bainha de Mielina/metabolismo , Norprogesteronas/farmacologia , Remielinização/fisiologia
5.
Int J Mol Sci ; 21(13)2020 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-32646017

RESUMO

Alzheimer's disease (AD) is a multifactorial age-related neurodegenerative disease that today has no effective treatment to prevent or slow its progression. Neuroactive steroids, including neurosteroids and sex steroids, have attracted attention as potential suitable candidates to alleviate AD pathology. Accumulating evidence shows that they exhibit pleiotropic neuroprotective properties that are relevant for AD. This review focuses on the relationship between selected neuroactive steroids and the main aspects of AD disease, pointing out contributions and gaps with reference to sex differences. We take into account the regulation of brain steroid concentrations associated with human AD pathology. Consideration is given to preclinical studies in AD models providing current knowledge on the neuroprotection offered by neuroactive (neuro)steroids on major AD pathogenic factors, such as amyloid-ß (Aß) and tau pathology, mitochondrial impairment, neuroinflammation, neurogenesis and memory loss. Stimulating endogenous steroid production opens a new steroid-based strategy to potentially overcome AD pathology. This article is part of a Special Issue entitled Steroids and the Nervous System.


Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Esteroides/metabolismo , Animais , Encéfalo/metabolismo , Humanos , Sistema Nervoso/metabolismo , Caracteres Sexuais , Proteínas tau/metabolismo
6.
Cereb Cortex ; 28(11): 3976-3993, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-29048465

RESUMO

The treatment of Alzheimer's disease (AD) remains challenging and requires a better in depth understanding of AD progression. Particularly, the link between amyloid protein precursor (APP) processing and Tau pathology development remains poorly understood. Growing evidences suggest that APP processing and amyloid-ß (Aß) release are upstream of Tau pathology but the lack of animal models mimicking the slow progression of human AD raised questions around this mechanism. Here, we described that an AD-like ßAPP processing in adults wild-type rats, yielding to human APP, ßCTF and Aß levels similar to those observed in AD patients, is sufficient to trigger gradual Tauopathy. The Tau hyperphosphorylation begins several months before the formation of both amyloid plaques and tangle-like aggregates in aged rats and without associated inflammation. Based on a longitudinal characterization over 30 months, we showed that extrasynaptic and emotional impairments appear before long-term potentiation deficits and memory decline and so before Aß and Tau aggregations. These compelling data allowed us to (1) experimentally confirm the causal relationship between ßAPP processing and Tau pathology in vivo and without Tau transgene overexpression, (2) support the amyloidogenic cascade and (3) propose a 4-step hypothesis of prodromal AD progression.


Assuntos
Doença de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Modelos Animais de Doenças , Hipocampo/metabolismo , Hipocampo/patologia , Proteínas tau/metabolismo , Idoso , Idoso de 80 Anos ou mais , Peptídeos beta-Amiloides/metabolismo , Animais , Progressão da Doença , Feminino , Vetores Genéticos , Humanos , Potenciação de Longa Duração , Masculino , Fragmentos de Peptídeos/metabolismo , Placa Amiloide/metabolismo , Presenilina-1/genética , Agregação Patológica de Proteínas/metabolismo , Ratos Wistar
7.
Psychoneuroendocrinology ; 83: 122-134, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28609670

RESUMO

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 GABAA 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.


Assuntos
Proteínas de Transporte/metabolismo , Oxazinas/metabolismo , Oxazinas/farmacocinética , Receptores de GABA-A/metabolismo , Animais , Ansiolíticos/farmacologia , Encéfalo/metabolismo , Encéfalo/patologia , Corticosterona/sangue , Relação Dose-Resposta a Droga , Isoquinolinas/farmacologia , Ligantes , Masculino , Plasma/metabolismo , Pregnenolona/metabolismo , Progesterona/metabolismo , Ratos , Ratos Sprague-Dawley , Esteroides/metabolismo
8.
Psychopharmacology (Berl) ; 231(17): 3293-3312, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24481566

RESUMO

RATIONALE: Pregnenolone sulfate (PREGS) and dehydroepiandrosterone sulphate (DHEAS) are pro-amnesic, anti-amnesic and neuroprotective steroids in rodents. In Alzheimer's disease (AD) patient's brains, their low concentrations are correlated with high levels of Aß and tau proteins. The unnatural enantiomer ent-PREGS enhanced memory in rodents. We investigated here whether ent-PREGS and ent-DHEAS could be neuroprotective in AD models. OBJECTIVE: The effects of PREGS, ent-PREGS, DHEAS and ent-DHEAS against Aß25-35 peptide-induced toxicity were examined in vitro on B104 neuroblastoma cells and in vivo in mice. METHODS: B104 cells pretreated with the steroids before Aß25-35 were analysed by flow cytometry measuring cell viability and death processes. Mice injected intracerebroventricularly with Aß25-35 and the steroids were analysed for their memory abilities. Additionally, lipid peroxidation levels in the hippocampus were measured. RESULTS: ent-PREGS and PREGS significantly attenuated the Aß25-35-induced decrease in cell viability. Both steroids prevented the Aß25-35-induced increase in late apoptotic cells. PREGS further attenuated the ratio of necrotic cells. ent-DHEAS and DHEAS significantly reduced the Aß25-35-induced toxicity and prevented the cells from entering late apoptosis and necrosis. All steroids stimulated neurite outgrowth per se and prevented the Aß25-35-induced decrease. In vivo, ent-PREGS and ent-DHEAS significantly attenuated the Aß25-35-induced decrease in memory (spontaneous alternation and passive avoidance) and an increase in lipid peroxidation levels. In contrast to the natural steroids, both enantiomers prevented amnesia when injected 6 h before Aß25-35 in contrast to the natural steroids. CONCLUSION: The unnatural steroids ent-PREGS and ent-DHEAS are potent neuroprotective agents and could be effective therapeutical tools in AD.


Assuntos
Peptídeos beta-Amiloides/antagonistas & inibidores , Peptídeos beta-Amiloides/toxicidade , Sulfato de Desidroepiandrosterona/farmacologia , Fármacos Neuroprotetores/farmacologia , Fragmentos de Peptídeos/antagonistas & inibidores , Fragmentos de Peptídeos/toxicidade , Pregnenolona/farmacologia , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Comportamento Animal/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Técnicas In Vitro , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Camundongos , Neuritos/efeitos dos fármacos , Ratos
9.
Age (Dordr) ; 33(4): 565-78, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21222044

RESUMO

A major problem of ageing is progressive impairment of neuronal function and ultimately cell death. Since sex steroids are neuroprotective, their decrease with age may underlie age-related neuronal degeneration. To test this, we examined Purkinje cell numbers, plasma sex steroids and cerebellar neurosteroid concentrations during normal ageing (wild-type mice, WT), in our model of precocious ageing (Rora(+/sg), heterozygous staggerer mice in which expression of the neuroprotective factor RORα is disrupted) and after long-term hormone insufficiency (WT post-gonadectomy). During normal ageing (WT), circulating sex steroids declined prior to or in parallel with Purkinje cell loss, which began at 18 months of age. Although Purkinje cell death was advanced in WT long-term steroid deficiency, this premature neuronal loss did not begin until 9 months, indicating that vulnerability to sex steroid deficiency is a phenomenon of ageing Purkinje neurons. In precocious ageing (Rora(+/sg)), circulating sex steroids decreased prematurely, in conjunction with marked Purkinje cell death from 9 months. Although Rora(+/sg) Purkinje cells are vulnerable through their RORα haplo-insufficiency, it is only as they age (after 9 months) that sex steroid failure becomes critical. Finally, cerebellar neurosteroids did not decrease with age in either genotype or gender; but were profoundly reduced by 3 months in male Rora(+/sg) cerebella, which may contribute to the fragility of their Purkinje neurons. These data suggest that ageing Purkinje cells are maintained by circulating sex steroids, rather than local neurosteroids, and that in Rora(+/sg) their age-related death is advanced by premature sex steroid loss induced by RORα haplo-insufficiency.


Assuntos
Envelhecimento/fisiologia , Morte Celular/fisiologia , Sobrevivência Celular/fisiologia , Cerebelo/metabolismo , Hormônios Esteroides Gonadais/fisiologia , Membro 1 do Grupo F da Subfamília 1 de Receptores Nucleares/fisiologia , Células de Purkinje/fisiologia , Animais , Castração , Contagem de Células , Cerebelo/citologia , Estradiol/sangue , Feminino , Hormônios Esteroides Gonadais/metabolismo , Terapia de Reposição Hormonal , Masculino , Camundongos , Camundongos Mutantes , Camundongos Mutantes Neurológicos , Progesterona/sangue , Células de Purkinje/citologia , Testosterona/sangue
10.
Eur Neuropsychopharmacol ; 21(2): 211-5, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21036556

RESUMO

This study examined the role of forebrain N-methyl-D-aspartate receptors (NMDA-Rs) in the promnesiant effects of natural (+) pregnenolone sulfate (PREGS) and its synthetic (-) enantiomer ent-PREGS in young adult mice. Using the two-trial arm discrimination task in a Y-maze, PREGS and ent-PREGS administration to control mice increased memory performances. In mice with a knock-out of the NR1 subunit of NMDA-Rs in the forebrain, the promnesiant effect of ent-PREGS was maintained whereas the activity of PREGS was lost. Memory enhancement by PREGS involves the NMDA-R activity in the hippocampal CA1 area and possibly in some locations of the cortical layers, whereas ent-PREGS acts independently of NMDA-R function.


Assuntos
Memória/efeitos dos fármacos , Pregnenolona/farmacologia , Prosencéfalo/efeitos dos fármacos , Esteroides/farmacologia , Animais , Hipocampo/efeitos dos fármacos , Hipocampo/fisiologia , Masculino , Memória/fisiologia , Camundongos , Camundongos Knockout , N-Metilaspartato/farmacologia , Receptores de N-Metil-D-Aspartato/deficiência , Receptores de N-Metil-D-Aspartato/fisiologia , Percepção Espacial/efeitos dos fármacos , Estereoisomerismo
11.
Neurochem Int ; 52(4-5): 522-40, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18068870

RESUMO

Pregnenolone sulfate (PREGS) has been shown, either at high nanomolar or at micromolar concentrations, to increase neuronal activity by inhibiting GABAergic and by stimulating glutamatergic neurotransmission. PREGS is also a potent modulator of sigma type 1 (sigma1) receptors. It has been proposed that these actions of PREGS underlie its neuropharmacological effects, and in particular its influence on memory processes. On the other hand, the PREGS-mediated increase in neuronal excitability may become dangerous under particular conditions, for example in the case of excitotoxic stress or convulsions. However, the physiopathological significance of these observations has recently been put into question by the failure to detect significant levels of PREGS within the brain and plasma of rats and mice, either by direct analytical methods based on liquid chromatography/mass spectrometry (LC/MS) or enzyme linked immunosorbent assay (ELISA) with specific antibodies against PREGS, or by indirect gas chromatography/mass spectrometry (GC/MS) analysis with improved sample workup. These recent results have not come to the attention of a large number of neurobiologists interested in steroid sulfates. However, although available direct analytical methods have failed to detect levels of PREGS above 0.1-0.3 ng/g in brain tissue, it may be premature to completely exclude the local formation of biologically active PREGS within specific and limited compartments of the nervous system. In contrast to the situation in rodents, significant levels of sulfated 3beta-hydroxysteroids have been measured in human plasma and brain. Previous indirect measures of steroid sulfates by radioimmunoassays (RIA) or GC/MS had detected elevated levels of PREGS in rodent brain. The discrepancies between the results of different assay procedures have revealed the danger of indirect analysis of steroid sulfates. Indeed, PREGS must be solvolyzed/hydrolyzed prior to RIA or GC/MS analysis, and it is the released, unconjugated PREG which is then quantified. Extreme caution needs to be exercised during the preparation of samples for RIA or GC/MS analysis, because the fraction presumed to contain only steroid sulfates can be contaminated by nonpolar components from which PREG is generated by the solvolysis/hydrolysis/derivatization reactions.


Assuntos
Encéfalo/fisiologia , Pregnenolona/fisiologia , Animais , Barreira Hematoencefálica/fisiologia , Química Encefálica , Humanos , Camundongos , Pregnenolona/antagonistas & inibidores , Pregnenolona/metabolismo , Ratos , Receptores de Neurotransmissores/efeitos dos fármacos , Receptores de Neurotransmissores/fisiologia , Sulfatases/metabolismo , Sulfotransferases/metabolismo
12.
Prog Neurobiol ; 84(1): 25-39, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18037225

RESUMO

Symptomatic medications, l-Dopa and dopaminergic agents, remain the only clinically pertinent pharmacological treatment proven effective and available for the large population of patients with Parkinson's disease. The challenge for the pharmaceutical industry is to develop disease-modifying drugs which could arrest, delay or at least oppose the progression of the specific pathogenic processes underlying Parkinson's disease. The purpose of this review, based on recent biological and genetic data to be validated with appropriate animal models, was to re-examine the putative neuroprotective agents in Parkinson's disease and discuss the development of new strategies with the ultimate goal of demonstrating neurocytoprotective activity in this neurodegenerative disease. Since guidelines for research on neurocytoprotective drugs remain to be written, innovation will be the key to success of future clinical trials. It is reasonable to expect that future advances in our understanding of the pathogenic processes of Parkinson's disease will open the way to new perspectives for the treatment of other neurodegenerative diseases.


Assuntos
Antiparkinsonianos/farmacologia , Citoproteção/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Doença de Parkinson/tratamento farmacológico , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Citoproteção/fisiologia , Modelos Animais de Doenças , Humanos , Degeneração Neural/tratamento farmacológico , Degeneração Neural/genética , Degeneração Neural/fisiopatologia , Doença de Parkinson/genética , Doença de Parkinson/fisiopatologia
13.
Endocr Rev ; 28(4): 387-439, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17431228

RESUMO

The utility and safety of postmenopausal hormone replacement therapy has recently been put into question by large clinical trials. Their outcome has been extensively commented upon, but discussions have mainly been limited to the effects of estrogens. In fact, progestagens are generally only considered with respect to their usefulness in preventing estrogen stimulation of uterine hyperplasia and malignancy. In addition, various risks have been attributed to progestagens and their omission from hormone replacement therapy has been considered, but this may underestimate their potential benefits and therapeutic promises. A major reason for the controversial reputation of progestagens is that they are generally considered as a single class. Moreover, the term progesterone is often used as a generic one for the different types of both natural and synthetic progestagens. This is not appropriate because natural progesterone has properties very distinct from the synthetic progestins. Within the nervous system, the neuroprotective and promyelinating effects of progesterone are promising, not only for preventing but also for reversing age-dependent changes and dysfunctions. There is indeed strong evidence that the aging nervous system remains at least to some extent sensitive to these beneficial effects of progesterone. The actions of progesterone in peripheral target tissues including breast, blood vessels, and bones are less well understood, but there is evidence for the beneficial effects of progesterone. The variety of signaling mechanisms of progesterone offers exciting possibilities for the development of more selective, efficient, and safe progestagens. The recognition that progesterone is synthesized by neurons and glial cells requires a reevaluation of hormonal aging.


Assuntos
Terapia de Reposição de Estrogênios/métodos , Fenômenos Fisiológicos do Sistema Nervoso , Congêneres da Progesterona/uso terapêutico , Progesterona/uso terapêutico , Progestinas/uso terapêutico , Envelhecimento/fisiologia , Animais , Feminino , Humanos , Neuroglia/efeitos dos fármacos , Neuroglia/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Progesterona/farmacologia , Congêneres da Progesterona/farmacologia , Progestinas/farmacologia
14.
Hum Psychopharmacol ; 22(4): 189-97, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17415706

RESUMO

According to Evidence-Based-Medicine, any proposal for the rationale treatment of mild cognitive impairment (MCI) must be based on the results of double-blind, randomized clinical trials (RCTs). However, since MCI at the present time does not constitute a homogeneous clinical syndrome, it is still inappropriate to propose a specific drug treatment. Moreover, RCTs assessing the therapeutic value of acetylcholinesterase-inhibitors (AChEIs) are negative either trying to improve symptoms (memory performance) or preventing the conversion from MCI to real Alzheimer's Disease (AD). The same negative results were obtained with drugs targeting some systems considered as the early steps of the pathophysiological cascade leading to dementia: non-steroidal anti-inflammatory compounds (rofecoxib), sex steroid hormones (testosterone, estrogens), or antioxidants (tocopherol). Either MCI is considered as the very early phase of development of AD (and then the treatments will aim at preventively antagonizing the hallmarks of the disease) or MCI is a new entity (and then the drugs will target the associated neurochemical disturbances such as tau protein or soluble Abeta oligomers); MCI could also be considered as a monosymptomatic syndrome (amnesia) leading to the development of pure pro-mnestic drugs. These three hypotheses will be presented on the basis of the neurobiology and the pharmacology, and examples of potentially active candidates will be discussed.


Assuntos
Transtornos Cognitivos/terapia , Idoso , Amnésia/psicologia , Amnésia/terapia , Amiloide/antagonistas & inibidores , Anti-Inflamatórios não Esteroides/uso terapêutico , Antioxidantes/uso terapêutico , Estimulantes do Sistema Nervoso Central/uso terapêutico , Inibidores da Colinesterase/uso terapêutico , Ensaios Clínicos como Assunto , Transtornos Cognitivos/psicologia , Agonistas de Dopamina/farmacologia , Hormônios Esteroides Gonadais/sangue , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Receptores Dopaminérgicos/efeitos dos fármacos
15.
Neuropsychiatr Dis Treat ; 3(1): 103-16, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19300541

RESUMO

Cognitive psychology has provided clinicians with specific tools for analyzing the processes of cognition (memory, language) and executive functions (attention-concentration, abstract reasoning, planning). Neuropsychology, coupled with the neurosciences (including neuroimaging techniques), has authenticated the existence of early disorders affecting the "superior or intellectual" functions of the human brain. The prevalence of cognitive and attention disorders is high in adults because all the diseases implicating the central nervous system are associated with cognitive correlates of variable intensity depending on the disease process and the age of the patient. In some pathologies, cognitive impairment can be a leading symptom such as in schizophrenia, posttraumatic stress disorder or an emblematic stigmata as in dementia including Alzheimer's disease. Paradoxically, public health authorities have only recognized as medications for improving cognitive symptoms those with proven efficacy in the symptomatic treatment of patients with Alzheimer's disease; the other cognitive impairments are relegated to the orphanage of syndromes and symptoms dispossessed of medication. The purpose of this review is to promote a true "pharmacology of cognition" based on the recent knowledge in neurosciences. Data from adult human beings, mainly concerning memory, language, and attention processes, will be reported. "Drug therapeutic strategies" for improving cognition (except for memory function) are currently rather scarce, but promising perspectives for a new neurobiological approach to cognitive pharmacology will be highlighted.

16.
Endocrinology ; 147(6): 2737-43, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16513833

RESUMO

Immortalized hypothalamic GT1-7 neurons represent a good model system to investigate the control of GnRH secretion. Using these cells, we observed that the neuroactive steroid, pregnenolone sulfate (PREGS), is able to stimulate the release of GnRH in a dose-dependent manner through N-methyl-D-aspartate (NMDA) receptors, because its action is completely blocked by a specific NMDA receptor antagonist and magnesium. GT1-7 neurons express mRNAs for various mouse NMDA receptor subunits (zeta,1, epsilon3, epsilon4, and epsilon2, corresponding to the NR1, NR2C, NR2D, and NR2B rat subunits) and increase their spontaneous release of GnRH when incubated in the presence of exogenous glutamate or NMDA. In addition, we found that these neurons are able to release and synthesize glutamate, as demonstrated by the presence of glutamate accumulated in the defined incubation medium of the neurons, during the experiment and the expression of mRNA coding for vesicular glutamate transporter 2, a specific marker of glutamatergic neurons. The potentiating effect of PREGS on the secretion of GnRH induced by glutamate is consistent with the role of the steroid as a positive allosteric modulator of NMDA receptors. Together these results point to a novel mechanism by which the neuroactive steroid PREGS may potentiate an autocrine excitatory loop in GnRH neurons.


Assuntos
Hormônio Liberador de Gonadotropina/metabolismo , Hipotálamo/efeitos dos fármacos , Pregnenolona/farmacologia , Receptores de N-Metil-D-Aspartato/fisiologia , Animais , Células Cultivadas , Ácido Glutâmico/metabolismo , Ácido Glutâmico/farmacologia , Glicina/metabolismo , Hipotálamo/metabolismo , Camundongos , N-Metilaspartato/farmacologia , RNA Mensageiro/análise , Receptores de AMPA/fisiologia , Receptores de GABA-A/fisiologia , Receptores de N-Metil-D-Aspartato/genética , Proteína Vesicular 2 de Transporte de Glutamato/genética
17.
Alzheimer Dis Assoc Disord ; 19(4): 226-39, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16327350

RESUMO

Neurodegenerative diseases and, in particular, Alzheimer disease, are characterized by progressive neuronal loss correlated in time with the symptoms of the disease considered. Whereas the symptoms of those incapacitating diseases are beginning to be managed with a relative efficacy, the ultimate objective of therapy nonetheless remains preventing cell (neuronal and/or astrocytic) death in a neurocytoprotective approach. In biologic terms, in the light of progress at basic research level, three strategies may be envisaged: (1) antagonizing the cytotoxic causal events (excess intracellular calcium, accumulation of abnormal proteins, excitotoxic effects of amino acids, oxidative stress, processes related to inflammation, etc.); (2) stimulating the endogenous protective processes (anti-free radical or DNA repair systems, production of neurotrophic factors, potential cytoprotective action of steroids, etc.); (3) promoting damaged structure repair strategies (grafts) or deep brain or cortical neurostimulation with a view to triggering (beyond the symptomatic actions) potential 'protective' cell mechanisms. The clinical transition of the various strategies whose efficacy is being tested in animal and/or cell models, experimental analogs of the diseases, and thus the objective demonstration in humans of pharmacological and/or surgical neurocytoprotection, is currently the subject of considerable methodological debate (What are the right psychometric assessment criteria? What are the most pertinent laboratory or neuroradiological markers, etc.?). A number of clinical trials have been completed or are ongoing with drugs that are reputed to be neuroprotective. Thus, elements of the response are beginning to be generated with a view to determining whether it will soon be possible to effectively slow or even stop the neurodegenerative process whose etiology, in most cases, remains obscure.


Assuntos
Doença de Alzheimer/fisiopatologia , Apoptose/efeitos dos fármacos , Doenças Neurodegenerativas/fisiopatologia , Neurônios/fisiologia , Fármacos Neuroprotetores/farmacologia , Doença de Alzheimer/prevenção & controle , Ensaios Clínicos como Assunto , Humanos , Doenças Neurodegenerativas/prevenção & controle , Fármacos Neuroprotetores/uso terapêutico
18.
Drugs Aging ; 22(9): 749-65, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16156679

RESUMO

The aim of this review is to establish the relationship between treatment with hypnotics and the risk of postural instability and as a consequence, falls and hip fractures, in the elderly. A review of the literature was performed through a search of the MEDLINE, Ingenta and PASCAL databases from 1975 to 2005. We considered as hypnotics only those drugs approved for treating insomnia, i.e. some benzodiazepines and the more recently launched 'Z'-compounds, i.e. zopiclone, zolpidem and zaleplon. Large-scale surveys consistently report increases in the frequency of falls and hip fractures when hypnotics are used in the elderly (2-fold risk). Benzodiazepines are the major class of hypnotics involved in this context; falls and fractures in patients taking Z-compounds are less frequently reported, and in this respect, zolpidem is considered as at risk in only one study. It is important to note, however, that drug adverse effect relationships are difficult to establish with this type of epidemiological data-mining. On the other hand, data obtained in laboratory settings, where confounding factors can be eliminated, prove that benzodiazepines are the most deleterious hypnotics at least in terms of their effects on body sway. Z-compounds are considered safer, probably because of their pharmacokinetic properties as well as their selective pharmacological activities at benzodiazepine-1 (BZ(1)) receptors. The effects of hypnotics on balance, gait and equilibrium are the consequence of differential negative impacts on vigilance and cognitive functions, and are highly dose- and time-dependent. Z-compounds have short half-lives and have less cognitive and residual effects than older medications. Some practical rules need to be followed when prescribing hypnotics in order to prevent falls and hip fractures as much as possible in elderly insomniacs, whether institutionalised or not. These are: (i) establish a clear diagnosis of the sleep disorder; (ii) take into account chronic conditions leading to balance and gait difficulties (motor and cognitive status); (iii) search for concomitant prescription of psychotropics and sedatives; (iv) use half the recommended adult dosage; and (v) declare any adverse effect to pharmacovigilance centres. Comparative pharmacovigilance studies focused on the impact of hypnotics on postural stability are very much needed.


Assuntos
Acidentes por Quedas , Benzodiazepinas/uso terapêutico , Fraturas do Quadril , Hipnóticos e Sedativos/uso terapêutico , Equilíbrio Postural/efeitos dos fármacos , Distúrbios do Início e da Manutenção do Sono/tratamento farmacológico , Acidentes por Quedas/economia , Acetamidas/uso terapêutico , Idoso , Idoso de 80 Anos ou mais , Compostos Azabicíclicos , Benzodiazepinas/efeitos adversos , Estudos de Casos e Controles , Fraturas do Quadril/economia , Fraturas do Quadril/etiologia , Humanos , Hipnóticos e Sedativos/efeitos adversos , Hipnóticos e Sedativos/farmacocinética , Farmacoepidemiologia , Piperazinas/uso terapêutico , Postura , Estudos Prospectivos , Piridinas/uso terapêutico , Pirimidinas/uso terapêutico , Estudos Retrospectivos , Medição de Risco , Zolpidem
19.
Pharmacol Biochem Behav ; 82(4): 712-20, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16388839

RESUMO

The peripheral benzodiazepine receptors (PBR) might be involved in certain pathophysiological events, such as anxiety, by stimulating the production of neuroactive steroids in the brain. A recent electrophysiological study has revealed an interaction between PK11195, a PBR ligand and the anxiolytic compound etifoxine at micromolar concentrations. The present work was aimed at further characterizing the etifoxine-PBR interaction. In membrane preparations from intact male rat forebrain, etifoxine uncompetitively inhibited the binding of [(3)H]PK11195 with an IC(50) = 18.3 +/- 1.2 microM, a value consistent with etifoxine plasma and brain concentrations measured after an anxiolytic-like dose (50 mg/kg). In vivo, that etifoxine dose was associated with increased concentrations of pregnenolone, progesterone, 5alpha-dihydroprogesterone and allopregnanolone in plasma and brain of sham-operated animals. In adrenalectomized and castrated rats, etifoxine enhanced the brain levels of these steroids, suggesting a stimulation of their local synthesis and/or a decrease of their disappearance rate, independently of peripheral sources. Finasteride, an inhibitor of 5alpha-reductase that converts progesterone into its 5alpha-reduced metabolites like allopregnanolone, attenuated the anti-conflict effect of etifoxine even though brain allopregnanolone contents were drastically reduced. These results indicate that following activation of the PBR in the brain, an increased cerebral production of allopregnanolone, a potent positive modulator of the GABA(A) receptor function, may partially contribute to the anxiolytic-like effects of etifoxine.


Assuntos
Ansiolíticos/farmacologia , Encéfalo/efeitos dos fármacos , Oxazinas/farmacologia , Receptores de GABA-A/efeitos dos fármacos , Esteroides/metabolismo , Animais , Encéfalo/metabolismo , Isoquinolinas/metabolismo , Masculino , Pregnanolona/metabolismo , Ensaio Radioligante , Ratos , Ratos Wistar
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