Efecto del esteroide sintético tibolona sobre la gliosis reactiva

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Farmacología. Fecha de lectura: 02-12-2019Cuando se produce un daño en el sistema nervioso central (SNC), las células gliales, como los astrocitos y la microglía, sufren una transformación adaptativa, denominada gliosis reactiva, que se caracteriza por un aumento en la liberación de factores pro- y antiinflamatorios. Además, los astrocitos y la microglía aumentan su actividad fagocítica tras la lesión, lo que facilita la reparación del tejido dañado. Aunque en principio la gliosis favorece el retorno a la homeostasis del tejido nervioso dañado, en ciertas condiciones puede producirse una respuesta glial incontrolada, por ejemplo en situaciones de neuroinflamación crónica, lo que llega a producir un aumento en el daño tisular. Y por este motivo en ocasiones es necesario controlarla. Los estrógenos son sustancias producidas por nuestro organismo tanto en la periferia como en el SNC. Aunque estas hormonas tienen efectos neuroprotectores, su utilización en clínica está limitada debido al aumento del riesgo de padecer cáncer de mama, endometrio y ovarios. Una alternativa al uso de estrógenos como agentes neuroprotectores son algunos esteroides sintéticos, utilizados actualmente para el tratamiento de los síntomas de la menopausia, como la tibolona. Este esteroide sufre una metabolización específica en cada tejido y sus metabolitos tienen afinidad por los receptores de estrógeno, de progesterona y de andrógenos. Estudios previos in vitro sugieren que la tibolona tiene acciones protectoras en células neurales. En este estudio se ha analizado su acción protectora en un modelo murino de lesión cerebral, con particular énfasis en su acción sobre la gliosis reactiva. Nuestros estudios se han complementado con un análisis in vitro sobre los mecanismos de acción de la tibolona en astrocitos y microglía. Nuestros resultados indican que la tibolona modula la respuesta de astrocitos y microglía y aumenta la supervivencia neuronal en la corteza cerebral lesionada. El análisis de las acciones de la tibolona in vitro sugiere acciones directas sobre las células gliales mediadas por receptores de estrógeno y andrógenos. Además, nuestros resultados indican que este esteroide regula la actividad fagocítica de astrocitos y microglía, lo cual podría contribuir a su acción neuroprotectora in vivo.When damage occurs in the central nervous system (CNS), glial cells, such as astrocytes and microglia, undergo an adaptive transformation, characterized by increased release of pro- and anti-inflammatory factors, referred to as reactive gliosis. In addition, astrocytes and microglia increase their phagocytic activity after injury, facilitating the repair of damaged tissue and the return to homeostasis. However, certain conditions, such as chronic neuroinflammation, lead to uncontrolled glial responses and tissue damage. For this reason, regulation of glial responses in these circumstances is key. Estrogens are naturally produced hormones, both in the periphery and in the CNS. Although they have been reported to have neuroprotective effects, their clinical use is limited due to the increased risk of breast, endometrial and ovarian cancer. An alternative to the use of estrogens as neuroprotective agents are some synthetic steroids, such as tibolone, currently used for the treatment of menopausal symptoms. Tibolone is a tissue-specific steroid and its metabolites have affinity for estrogen, progesterone and androgen receptors. Previous in vitro studies suggest that tibolone has protective actions in neural cells. In this study, its protective action was analyzed in a mouse model of brain injury, with particular emphasis on its action on reactive gliosis. Our studies have been complemented with an in vitro analysis on the mechanisms of action of tibolone in astrocytes and microglia. Our results indicate that tibolone reduces the response of astrocytes and microglia and increases neuron survival in the injured cerebral cortex. Analysis of the actions of tibolone in vitro suggests direct actions on glial cells mediated by estrogen and androgen receptors. In addition, our results indicate that this steroid regulates the phagocytic activity of astrocytes and microglia, which could contribute to its neuroprotective action in viv

High-fat diet alters stress behavior, inflammatory parameters and gut microbiota in Tg APP mice in a sex-specific manner

Long-term high-fat diet (HFD) consumption commonly leads to obesity, a major health concern of western societies and a risk factor for Alzheimer's disease (AD). Both conditions present glial activation and inflammation and show sex differences in their incidence, clinical manifestation, and disease course. HFD intake has an important impact on gut microbiota, the bacteria present in the gut, and microbiota dysbiosis is associated with inflammation and certain mental disorders such as anxiety. In this study, we have analyzed the effects of a prolonged (18 weeks, starting at 7 months of age) HFD on male and female mice, both wild type (WT) and TgAPP mice, a model for AD, investigating the behavioral profile, gut microbiota composition and inflammatory/phagocytosis-related gene expression in hippocampus. In the open-field test, no overt differences in motor activity were observed between male and female or WT and TgAPP mice on a low-fat diet (LFD). However, HFD induced anxiety, as judged by decreased motor activity and increased time in the margins in the open-field, and a trend towards increased immobility time in the tail suspension test, with increased defecation. Intriguingly, female TgAPP mice on HFD showed less immobility and defecation compared to female WT mice on HFD. HFD induced dysbiosis of gut microbiota, resulting in reduced microbiota diversity and abundance compared with LFD fed mice, with some significant differences due to sex and little effect of genotype. Gene expression of pro-inflammatory/phagocytic markers in the hippocampus were not different between male and female WT mice, and in TgAPP mice of both sexes, some cytokines (IL-6 and IFN¿) were higher than in WT mice on LFD, more so in female TgAPP (IL-6). HFD induced few alterations in mRNA expression of inflammatory/phagocytosis-related genes in male mice, whether WT (IL-1ß, MHCII), or TgAPP (IL-6). However, in female TgAPP, altered gene expression returned towards control levels following prolonged HFD (IL-6, IL-12ß, TNF¿, CD36, IRAK4, PYRY6). In summary, we demonstrate that HFD induces anxiogenic symptoms, marked alterations in gut microbiota, and increased expression of inflammatory genes, except for female TgAPP that appear to be resistant to the diet effects. Lifestyle interventions should be introduced to prevent AD onset or exacerbation by reducing inflammation and its associated symptoms; however, our results suggest that the eventual goal of developing prevention and treatment strategies should take sex into consideration.This work was supported by Ministerio de Economía, Industria y Competitividad (MINECO), Grant Numbers BFU2014-51836-C2-1-R to LMGS and MAA, BFU2014-51836-C2-2-R and BFU2017-82565-C21-R2 to JAC; Madrid Council S2010/BMD-2349 to MLC; Centre for Biomedical Network Research for Physiopathology of Obesity and Nutrition (CIBEROBN) to JAC, Centre for Biomedical Network Research for Frailty and Healthy Ageing (CIBERFES) to LMGS and MAA, and Centre for Biomedical Network Research for Neurodegenerative Diseases (CIBERNED) to MLC. AC-C was granted with a FPI fellowship by the MINECO (BES-2015-072980)

Non-motor symptom burden in patients with Parkinson's disease with impulse control disorders and compulsive behaviours : results from the COPPADIS cohort

The study was aimed at analysing the frequency of impulse control disorders (ICDs) and compulsive behaviours (CBs) in patients with Parkinson's disease (PD) and in control subjects (CS) as well as the relationship between ICDs/CBs and motor, nonmotor features and dopaminergic treatment in PD patients. Data came from COPPADIS-2015, an observational, descriptive, nationwide (Spain) study. We used the validated Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) for ICD/CB screening. The association between demographic data and ICDs/CBs was analyzed in both groups. In PD, this relationship was evaluated using clinical features and treatment-related data. As result, 613 PD patients (mean age 62.47 ± 9.09 years, 59.87% men) and 179 CS (mean age 60.84 ± 8.33 years, 47.48% men) were included. ICDs and CBs were more frequent in PD (ICDs 12.7% vs. 1.6%, p < 0.001; CBs 7.18% vs. 1.67%, p = 0.01). PD patients had more frequent previous ICDs history, premorbid impulsive personality and antidepressant treatment (p < 0.05) compared with CS. In PD, patients with ICDs/CBs presented younger age at disease onset, more frequent history of previous ICDs and premorbid personality (p < 0.05), as well as higher comorbidity with nonmotor symptoms, including depression and poor quality of life. Treatment with dopamine agonists increased the risk of ICDs/CBs, being dose dependent (p < 0.05). As conclusions, ICDs and CBs were more frequent in patients with PD than in CS. More nonmotor symptoms were present in patients with PD who had ICDs/CBs compared with those without. Dopamine agonists have a prominent effect on ICDs/CBs, which could be influenced by dose

Microglial and Astrocytic Function in Physiological and Pathological Conditions: Estrogenic Modulation

© 2020 by the authors.There are sexual differences in the onset, prevalence, and outcome of numerous neurological diseases. Thus, in Alzheimer’s disease, multiple sclerosis, and major depression disorder, the incidence in women is higher than in men. In contrast, men are more likely to present other pathologies, such as amyotrophic lateral sclerosis, Parkinson’s disease, and autism spectrum. Although the neurological contribution to these diseases has classically always been studied, the truth is that neurons are not the only cells to be affected, and there are other cells, such as glial cells, that are also involved and could be key to understanding the development of these pathologies. Sexual differences exist not only in pathology but also in physiological processes, which shows how cells are differentially regulated in males and females. One of the reasons these sexual differences may occur could be due to the different action of sex hormones. Many studies have shown an increase in aromatase levels in the brain, which could indicate the main role of estrogens in modulating proinflammatory processes. This review will highlight data about sex differences in glial physiology and how estrogenic compounds, such as estradiol and tibolone, could be used as treatment in neurological diseases due to their anti-inflammatory effects and the ability to modulate glial cell functions.This research was funded by Agencia Estatal de Investigación (AEI), co-funded by Fondo Europeo de Desarrollo Regional (FEDER), grant number BFU2017-82754-R, and by Centro de Investigación Biomédica en red (CIBERFES).Peer reviewe

Aging and sex: Impact on microglia phagocytosis

Microglia dysfunction and activation are important hallmarks of the aging brain and are concomitant with age-related neurodegeneration and cognitive decline. Age-associated changes in microglia migration and phagocytic capacity result in maladaptive responses, chronic neuroinflammation, and worsened outcomes in neurodegenerative disorders. Given the sex bias in the incidence, prevalence, and therapy response of most neurological disorders, we have here examined whether the phagocytic activity of aged microglia is different in males and females. With this aim, the phagocytosis activity of male and female cells was compared in an in vitro aged microglia model and in microglia isolated from adult (5-month-old) or aged (18-month-old) mice. In both models, the phagocytosis of neural debris increased with aging in male and female cells and was higher in aged female microglia than in aged male cells. However, female aged microglia lost its ability to adapt its phagocytic activity to inflammatory conditions. These findings suggest that microglia phagocytosis of neural debris may represent a previously unexplored neuroprotective characteristic of aged microglia that may contribute to the generation of sex differences in the manifestation of neurodegenerative diseases.The study was supported by a grant from Agencia Estatal de Investigación (AEI), co-funded by Fondo Europeo de Desarrollo Regional (FEDER): BFU2017-82754-R and by CIBERFES

The synthetic steroid tibolone exerts sex-specific regulation of astrocyte phagocytosis under basal conditions and after an inflammatory challenge

[Background]: Tibolone is a synthetic steroid used in clinical practice for the treatment of climacteric symptoms and osteoporosis. Active metabolites of tibolone, generated in target tissues, have an affinity for estrogen and androgen receptors. Astrocytes are direct targets for estrogenic compounds and previous studies have shown that tibolone protects brain cortical neurons in association with a reduction in reactive astrogliosis in a mouse model of traumatic brain injury. Since phagocytosis is a crucial component of the neuroprotective function exerted by astrocytes, in the present study, we have assessed whether tibolone regulates phagocytosis in primary astrocytes incubated with brain-derived cellular debris.[Methods]: Male and female astrocyte cell cultures were obtained from newborn (P0-P2) female and male Wistar rats. Astrocytic phagocytosis was first characterized using carboxylate beads, Escherichia coli particles, or brain-derived cellular debris. Then, the effect of tibolone on the phagocytosis of Cy3-conjugated cellular debris was quantified by measuring the intensity of Cy3 dye-emitted fluorescence in a given GFAP immunoreactive area. Before the phagocytosis assays, astrocytes were incubated with tibolone in the presence or absence of estrogen or androgen receptor antagonists or an inhibitor of the enzyme that synthesizes estradiol. The effect of tibolone on phagocytosis was analyzed under basal conditions and after inflammatory stimulation with lipopolysaccharide.[Results]: Tibolone stimulated phagocytosis of brain-derived cellular debris by male and female astrocytes, with the effect being more pronounced in females. The effect of tibolone in female astrocytes was blocked by a selective estrogen receptor β antagonist and by an androgen receptor antagonist. None of these antagonists affected tibolone-induced phagocytosis in male astrocytes. In addition, the inhibition of estradiol synthesis in the cultures enhanced the stimulatory effect of tibolone on phagocytosis in male astrocytes but blocked the effect of the steroid in female cells under basal conditions. However, after inflammatory stimulation, the inhibition of estradiol synthesis highly potentiated the stimulation of phagocytosis by tibolone, particularly in female astrocytes.[Conclusions]: Tibolone exerts sex-specific regulation of phagocytosis in astrocytes of both sexes, both under basal conditions and after inflammatory stimulation.This study is supported by a grant from Agencia Estatal de Investigación (AEI), co-funded by Fondo Europeo de Desarrollo Regional (FEDER): BFU2017-82754-R, and by CIBERFES: CB16/10/00383.Peer reviewe

Estrogenic Regulation of Glia and Neuroinflammation

Estrogens are rapid and potent facilitators of synaptic plasticity in the adult brain; however, the steps that link estrogens to factors that regulate synaptic strength remain unclear. The present chapter will first review the acute effects of 17β‎-estradiol on synaptic transmission and long-term potentiation (LTP). It will then describe a synaptic model used to study the substrates of LTP and provide evidence for the ability of estradiol to rapidly engage a selective actin signaling cascade associated with the consolidation of LTP. Finally, it will be shown that chronic reductions in estradiol levels disrupt LTP and actin dynamics but can be reversed by acute infusions of the hormone. It is concluded here that estradiol can promote learning-related plasticity by modifying the synaptic cytoskeleton.Authors acknowledge economic support from Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Spain

Curso CSIC: Una visión actualizada de la neurociencia desde el Instituto Cajal

El impresionante avance de la investigación en Neurociencia del último siglo ha arrojado luz acerca de la estructura y funcionamiento del sistema nervioso central. La Neurociencia ha experimentado increíbles avances que han permitido no sólo ampliar nuestro conocimiento acerca de cómo funcionan procesos mentales como la memoria o el aprendizaje, sino también diseñar terapias específicas para enfermedades neurodegenerativas o desarrollar tecnologías de elevado impacto social como es el caso de la inteligencia artificial. En este curso, se hará un recorrido general sobre la historia de la Neurociencia, incidiendo en la estructura macroscópica y microscópica del cerebro y médula espinal, así como patologías asociadas al desarrollo y en el adulto. También se comentarán los últimos datos acerca de disciplinas asociadas como la inteligencia artificial y los trastornos de la conducta alimentaria, así como campos emergentes como la Neuroeducación. Finalmente, se plantearán las técnicas y modelos disponibles para el estudio de la Neurociencia, y se propondrán fuentes para la búsqueda de noticias y recursos científicos fiables

The synthetic steroid tibolone decreases reactive gliosis and neuronal death in the cerebral cortex of female mice after a stab wound injury

Previous studies have shown that estradiol reduces reactive gliosis after a stab wound injury in the cerebral cortex. Since the therapeutic use of estradiol is limited by its peripheral hormonal effects, it is of interest to determine whether synthetic estrogenic compounds with tissue-specific actions regulate reactive gliosis. Tibolone is a synthetic steroid that is widely used for the treatment of climacteric symptoms and/or the prevention of osteoporosis. In this study, we have assessed the effect of tibolone on reactive gliosis in the cerebral cortex after a stab wound brain injury in ovariectomized adult female mice. By 7 days after brain injury, tibolone reduced the number of glial fibrillary acidic protein (GFAP) immunoreactive astrocytes, the number of ionized calcium binding adaptor molecule 1 (Iba1) immunoreactive microglia, and the number of microglial cells with a reactive phenotype in comparison to vehicle-injected animals. These effects on gliosis were associated with a reduction in neuronal loss in the proximity to the wound, suggesting that tibolone exerts beneficial homeostatic actions in the cerebral cortex after an acute brain injury