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Environmental enrichment (EE) is a paradigm that offers the animal a plethora of stimuli, including physical, cognitive, sensory, and social enrichment. Exposure to EE can modulate both anxiety responses and plasma corticosterone. In this study, our objective was to explore how chronic unpredictable stress (CUS) impacts anxiety-related behaviors in male Swiss mice raised in EE conditions. Additionally, we investigated corticosterone and adrenocorticotropic hormone (ACTH) levels to assess the involvement of the hypothalamic-pituitary-adrenal (HPA) axis in mediating these responses. Mice were housed under either EE or standard housing conditions for 21 days. Afterward, they were exposed to 11 days of CUS while still reared in their distinct housing conditions, with half of the mice receiving daily pretreatment with the vehicle and the other half receiving daily metyrapone (MET) injections, an inhibitor of steroid synthesis, 30 mins before CUS exposure. Blood samples were obtained to assess plasma corticosterone and ACTH levels. The 11-day CUS protocol induced anxiety-like phenotype and elevated ACTH levels in EE mice. Chronic MET pretreatment prevented anxiety-like behavior in the EE-CUS groups, by mechanisms involving increased plasma corticosterone levels and decreased ACTH. These results suggest a role of the HPA axis in the mechanism underlying the anxiogenic phenotype induced by CUS in EE mice and shed light on the complex interplay between environmental factors, stress, and the HPA axis in anxiety regulation.
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Hormônio Adrenocorticotrópico , Ansiedade , Corticosterona , Meio Ambiente , Sistema Hipotálamo-Hipofisário , Sistema Hipófise-Suprarrenal , Estresse Psicológico , Animais , Masculino , Sistema Hipotálamo-Hipofisário/metabolismo , Camundongos , Sistema Hipófise-Suprarrenal/metabolismo , Estresse Psicológico/metabolismo , Hormônio Adrenocorticotrópico/sangue , Corticosterona/sangue , Metirapona/farmacologia , Comportamento Animal/fisiologia , Abrigo para Animais , Aprendizagem em Labirinto/fisiologiaRESUMO
Ouabain (OUA) is a cardiotonic steroid that modulates Na+, K+ -ATPase activity. OUA has been identified as an endogenous substance that is present in human plasma, and it has been shown to be associated with the response to acute stress in both animals and humans. Chronic stress is a major aggravating factor in psychiatric disorders, including depression and anxiety. The present work investigates the effects of the intermittent administration of OUA (1.8 µg/kg) during the chronic unpredictable stress (CUS) protocol in a rat's central nervous system (CNS). The results suggest that the intermittent OUA treatment reversed CUS-induced HPA axis hyperactivity through a reduction in (i) glucocorticoids levels, (ii) CRH-CRHR1 expression, and by decreasing neuroinflammation with a reduction in iNOS activity, without interfering with the expression of antioxidant enzymes. These changes in both the hypothalamus and hippocampus may reflect in the rapid extinction of aversive memory. The present data demonstrate the ability of OUA to modulate the HPA axis, as well as to revert CUS-induced long-term spatial memory deficits.
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Studies investigated how stressful experiences modulate physiological and behavioral responses and the consequences of stress-induced corticosterone release in anxiety-like behavior. Adolescence is crucial to brain maturation, and several neurobiological changes in this period lead individuals to increased susceptibility or resilience to aversive situations. Despite the effects of stress in adults, information about adolescents' responses to acute stress is lacking. We aimed to understand how adolescence affects acute stress responses. Male adolescent rats (30 days old) were 2 h restrained, and anxiety-like behaviors were measured immediately or 10 days after stress in the elevated plus-maze (EPM) and the light-dark box (LDB) tests. To verify the importance of CORT modulation in stress-induced anxiety, another group of rats was treated, 30 min before restraint, with metyrapone to blunt the stress-induced CORT peak and tested immediately after stress. To show that stress effects on behavior were age-dependent, another set of rats was tested in two different periods - early adolescence (30 days old) and mid-adolescence (40 days old) and were treated or not with metyrapone before the stress session and tested immediately or ten days later in the LDB test. Only early adolescent male rats were resilient to delayed anxiety-like behavior in EPM and LDB tests. Metyrapone treatment increased the rats' exploration immediately and ten days after stress. These data suggest a specific age at which adolescent rats are resilient to the delayed effects of acute restraint stress and that the metyrapone treatment has long-term behavioral consequences.
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Glucocorticoides , Metirapona , Ratos , Animais , Masculino , Glucocorticoides/farmacologia , Metirapona/farmacologia , Ansiedade/induzido quimicamente , Transtornos de Ansiedade , Corticosterona/farmacologia , Estresse Psicológico/complicações , Comportamento AnimalRESUMO
COVID-19 causes more than million deaths worldwide. Although much is understood about the immunopathogenesis of the lung disease, a lot remains to be known on the neurological impact of COVID-19. Here, we evaluated immunometabolic changes using astrocytes in vitro and dissected brain areas of SARS-CoV-2 infected Syrian hamsters. We show that SARS-CoV-2 alters proteins of carbon metabolism, glycolysis, and synaptic transmission, many of which are altered in neurological diseases. Real-time respirometry evidenced hyperactivation of glycolysis, further confirmed by metabolomics, with intense consumption of glucose, pyruvate, glutamine, and alpha ketoglutarate. Consistent with glutamine reduction, the blockade of glutaminolysis impaired viral replication and inflammatory response in vitro. SARS-CoV-2 was detected in vivo in hippocampus, cortex, and olfactory bulb of intranasally infected animals. Our data evidence an imbalance in important metabolic molecules and neurotransmitters in infected astrocytes. We suggest this may correlate with the neurological impairment observed during COVID-19, as memory loss, confusion, and cognitive impairment.
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COVID-19 , Animais , Astrócitos , Carbono , Cricetinae , Modelos Animais de Doenças , Glucose , Glutamina , Ácidos Cetoglutáricos , Mesocricetus , Piruvatos , SARS-CoV-2RESUMO
Transient global ischemia is a leading cause of learning and memory dysfunction and induces a pattern of delayed neuronal death in the CA1 subfield of the hippocampus by down-regulating GluR2 mRNA AMPA receptors in this cerebral area. This study sought to investigate the neuroprotective effect of coumestrol against spatial memory impairment induced by global ischemia that leads to neural death by reducing the GluR2 receptors content in the hippocampal CA1 area. Our studies demonstrated that coumestrol administration prevented spatial memory deficits in mice. These findings suggest a cognitive enhancement role of coumestrol against cognitive impairment in ischemic events.
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Isquemia Encefálica , Ataque Isquêmico Transitório , Fármacos Neuroprotetores , Animais , Isquemia Encefálica/complicações , Isquemia Encefálica/tratamento farmacológico , Cumestrol , Hipocampo/metabolismo , Isquemia , Ataque Isquêmico Transitório/complicações , Ataque Isquêmico Transitório/tratamento farmacológico , Ataque Isquêmico Transitório/genética , Transtornos da Memória/tratamento farmacológico , Transtornos da Memória/etiologia , Camundongos , Fármacos Neuroprotetores/farmacologia , Receptores de AMPA/metabolismo , Aprendizagem EspacialRESUMO
Background and Aim: Cortisol binds to mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) found in the hippocampus. The balanced expression of these receptors is essential to neuronal survival as MR and GR activations have antiapoptotic and proapoptotic effects, respectively. Given the aging changes in dogs' dentate gyrus (DG) and the possible involvement of cortisol receptors in this process, this study aimed to evaluate the expression of MR and GR and neuronal degeneration in this hippocampal region of aged dogs. Materials and Methods: This study included cadaveric histologic hippocampus sections from six dogs aged 10 years and older (AG group) and 12 young/adult dogs aged up to 8 years (YAd group). Nissl staining and immunohistochemistry were performed to identify cells and investigate MR and GR expression, respectively. Furthermore, fluorescent labeling (fluoro-Jade B) was used to detect degenerating neurons. Results: The AG group's polymorphic layer of the DG had a lower cell count (16%) and more degenerating neurons than the YAd group. In addition to these cellular changes, the AG group had lower MR immunoreactivity and MR-to-GR ratio. Furthermore, the lowest MR expression was associated with neuronal degeneration in the polymorphic layer of the DG of dogs. Conclusion: An imbalance in the MR-to-GR ratio was observed in the polymorphic layer of the DG of aged dogs, along with lower MR expression and a greater number of degenerating neurons. These findings have clinical implications for understanding the decline in hippocampal memory formation associated with cognitive changes in aged dogs.
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Recently, much attention has been drawn to the importance of the impact of infectious disease on human cognition. Several theories have been proposed, to explain the cognitive decline following an infection as well as to understand better the pathogenesis of human dementia, especially Alzheimer's disease. This article aims to review the state of the art regarding the knowledge about the impact of acute viral infections on human cognition, laying a foundation to explore the possible cognitive decline followed coronavirus disease 2019 (COVID-19). To reach this goal, we conducted a narrative review systematizing six acute viral infections as well as the current knowledge about COVID-19 and its impact on human cognition. Recent findings suggest probable short- and long-term COVID-19 impacts in cognition, even in asymptomatic individuals, which could be accounted for by direct and indirect pathways to brain dysfunction. Understanding this scenario might help clinicians and health leaders to deal better with a wave of neuropsychiatric issues that may arise following COVID-19 pandemic as well as with other acute viral infections, to alleviate the cognitive sequelae of these infections around the world.
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COVID-19 , Disfunção Cognitiva , COVID-19/complicações , COVID-19/epidemiologia , Disfunção Cognitiva/epidemiologia , Disfunção Cognitiva/virologia , Humanos , Pandemias , SARS-CoV-2RESUMO
The persistence of anxiety and the deficit of fear memory extinction are both phenomena related to the symptoms of a trauma-related disorder, such as post-traumatic stress disorder (PTSD). Recently we have shown that single acute restraint stress (2 h) in rats induces a late anxiety-related behavior (observed ten days after stress), whereas, in the present work, we found that the same stress impaired fear extinction in animals conditioned ten days after stress. Fourteen days of environmental enrichment (EE) prevented the deleterious effect of stress on fear memory extinction. Additionally, we observed that EE prevented the stress-induced increase in AMPA receptor GluA1 subunit phosphorylation in the hippocampus, but not in the basolateral amygdala complex and the frontal cortex, indicating a potential mechanism by which it exerts its protective effect against the stress-induced behavioral outcome.
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Medo , Transtornos de Estresse Pós-Traumáticos , Animais , Extinção Psicológica , Hipocampo , Fosforilação , Ratos , Estresse Psicológico , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol PropiônicoRESUMO
The embryonic stage is the most vulnerable period for congenital abnormalities. Due to its prolonged developmental course, the central nervous system (CNS) is susceptible to numerous genetic, epigenetic, and environmental influences. During embryo implantation, the CNS is more vulnerable to external influences such as environmental tobacco smoke (ETS), increasing the risk for delayed fetal growth, sudden infant death syndrome, and immune system abnormalities. This study aimed to evaluate the effects of in utero exposure to ETS on neuroinflammation in the offspring of pregnant mice challenged or not with lipopolysaccharide (LPS). After the confirmation of mating by the presence of the vaginal plug until offspring birth, pregnant C57BL/6 mice were exposed to either 3R4F cigarettes smoke (Kentucky University) or compressed air, twice a day (1h each), for 21 days. Enhanced glial cell and mixed cell cultures were prepared from 3-day-old mouse pups. After cell maturation, both cells were stimulated with LPS or saline. To inhibit microglia activation, minocycline was added to the mixed cell culture media 24 h before LPS challenge. To verify the influence of in utero exposure to ETS on the development of neuroinflammatory events in adulthood, a different set of 8-week-old animals was submitted to the Autoimmune Experimental Encephalomyelitis (EAE) model. The results indicate that cells from LPS-challenged pups exposed to ETS in utero presented high levels of proinflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNFα) and decreased cell viability. Such a proinflammatory environment could modulate fetal programming by an increase in microglia and astrocytes miRNA155. This scenario may lead to the more severe EAE observed in pups exposed to ETS in utero.
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RATIONALE: Studies point out a higher prevalence of posttraumatic stress disorder (PTSD) in individuals with diabetes mellitus. It is known that glucocorticoid (GR) and mineralocorticoid (MR) receptors are implicated in fear memory processes and PTSD. However, there is no preclinical studies addressing the involvement of these receptors on abnormal fear memories related to diabetic condition. OBJECTIVES: By inducing a contextual conditioned fear memory, we generate a suitable condition to investigate the extinction and the generalization of the fear memory in streptozotocin-induced diabetic (DBT) rats alongside the expression of the cytosolic and nuclear GR and MR in the hippocampus (HIP) and prefrontal cortex (PFC). Moreover, we investigated the involvement of the MR or GR on the acquisition of fear memory extinction and on the generalization of this fear memory. When appropriate, anxiety-related behavior was evaluated. METHODS: Male Wistar rats received one injection of steptozotocin (i.p.) to induce diabetes. After 4 weeks, the animals (DBTs and non-DBTs) were subjected to a conditioned contextual fear protocol. RESULTS: The expression of MR and GR in the HIP and PFC was similar among all the groups. The single injection of MR agonist was able to facilitate the acquisition of the impaired fear memory extinction in DBTs animals together with the impairment of its generalization. However, the GR antagonism impaired only the generalization of this fear memory which was blocked by the previous injection of the MR antagonist. All treatments were able to exert anxiolytic-like effects. CONCLUSIONS: The results indicate that MR activation in DBT animals disrupts the overconsolidation of aversive memory, without discarding the involvement of emotional behavior in these processes.
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Diabetes Mellitus Experimental/metabolismo , Extinção Psicológica/fisiologia , Medo/fisiologia , Generalização Psicológica/fisiologia , Memória/fisiologia , Receptores de Mineralocorticoides/metabolismo , Animais , Diabetes Mellitus Experimental/psicologia , Extinção Psicológica/efeitos dos fármacos , Medo/efeitos dos fármacos , Medo/psicologia , Fludrocortisona/farmacologia , Generalização Psicológica/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Memória/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Ratos , Ratos Wistar , Receptores de Mineralocorticoides/agonistasRESUMO
Multiple sclerosis (MS) is an autoimmune and neuroinflammatory disease characterized by demyelination of the Central Nervous System. Immune cells activation and release of pro-inflammatory cytokines play a crucial role in the disease modulation, decisively contributing to the neurodegeneration observed in MS and the experimental autoimmune encephalomyelitis (EAE), the widely used MS animal model. Synthetic glucocorticoids, commonly used to treat the MS attacks, have controversial effects on neuroinflammation and cognition. We sought to verify the influence of dexamethasone (DEX) on the EAE progression and on EAE-induced cognitive deficits. In myelin oligodendrocyte glycoprotein peptide (MOG35-55)-induced EAE female mice, treated once with DEX (50 mg/kg) or not, on the day of immunization, DEX decreased EAE-induced motor clinical scores, infiltrating cells in the spinal cord and delayed serum corticosterone peak. At the asymptomatic phase (8-day post-immunization), DEX did not protected from the EAE-induced memory consolidation deficits, which were accompanied by increased glucocorticoid receptor (GR) activity and decreased EGR-1 expression in the hippocampus. Blunting hippocampal GR genomic activation with DnGR vectors prevented DEX effects on EAE-induced memory impairment. These data suggest that, although DEX improves clinical signs, it decreases cognitive and memory capacity by diminishing neuronal activity and potentiating some aspects of neuroinflammation in EAE.
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Anti-Inflamatórios/administração & dosagem , Dexametasona/administração & dosagem , Encefalomielite Autoimune Experimental/complicações , Encefalomielite Autoimune Experimental/tratamento farmacológico , Aprendizagem/efeitos dos fármacos , Memória/efeitos dos fármacos , Transtornos Motores/etiologia , Transtornos Motores/prevenção & controle , Animais , Anti-Inflamatórios/farmacocinética , Corticosterona/sangue , Dexametasona/farmacocinética , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/diagnóstico , Imunofluorescência , Hipocampo/metabolismo , Hipocampo/patologia , Camundongos , Camundongos Endogâmicos C57BL , Transtornos Motores/fisiopatologia , Esclerose Múltipla/complicações , Esclerose Múltipla/tratamento farmacológico , Receptores de Glucocorticoides/metabolismo , Medula Espinal/metabolismo , Medula Espinal/patologiaRESUMO
Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the expression of an array of enzymes with important detoxifying and antioxidant functions. Current findings support the role of high levels of oxidative stress in the pathogenesis of neurological disorders. Given the central role played by Nrf2 in counteracting oxidative damage, a number of studies have targeted the modulation of this transcription factor in order to confer neuroprotection. Nrf2 activity is tightly regulated by oxidative stress and energy-based stimuli. Thus, many dietary interventions based on energy intake regulation, such as dietary energy restriction (DER) or high-fat diet (HFD), modulate Nrf2 with consequences for a variety of cellular processes that affect brain health. DER, by either restricting calorie intake or meal frequency, activates Nrf2 thereby triggering its protective effects, whilst HFD inhibit this pathway, thereby exacerbating oxidative stress. Consequently, DER protocols can be valuable strategies in the management of central nervous system (CNS) disorders. Herein, we review current knowledge of the role of Nrf2 signaling in neurological diseases, namely Alzheimer's disease, Parkinson's disease, multiple sclerosis and cerebral ischemia, as well as the potential of energy intake regulation in the management of Nrf2 signaling.
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Chronic psychogenic stress can increase neuronal calcium influx and generate the intracellular accumulation of oxidative (ROS) and nitrosative (RNS) reactive species, disrupting synaptic transmission in the brain. These molecules impair the Na,K-ATPase (NKA) activity, whose malfunction has been related to neuropsychiatric disorders, including anxiety, depression, schizophrenia, and neurodegenerative diseases. In this study, we assessed how 14â¯days of restraint stress in rats affect NKA activity via oxidative/nitrosative damage in the frontal cortex (FCx), a crucial region for emotional and cognitive control. One day after the last stress session (S14â¯+â¯1d), but not immediately after the last stress session (S14), α2,3-NKA activity was significantly reduced in the FCx, without changes in the protein levels. The S14â¯+â¯1d animals also showed increased lipid peroxidation, iNOS, and AP-1 activities, as well as TNF-α protein levels, evidencing oxidative stress and neuroinflammation. No cellular death or neurodegeneration was observed in the FCx of S14â¯+â¯1d animals. Pharmacological inhibition of iNOS or COX-2 before each stress session prevented lipid peroxidation and the α2,3-NKA activity loss. Our results show that repeated restraint exposure for 14â¯days decreases the activity of α2,3-NKA in FCx 24â¯h after the last stress, an effect associated with augmented inflammatory response and oxidative and nitrosative damage and suggest new pathophysiological roles to neuroinflammation in neuropsychiatric diseases.
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Lobo Frontal/metabolismo , Estresse Nitrosativo/fisiologia , Estresse Oxidativo/fisiologia , Restrição Física , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Ciclo-Oxigenase 2/metabolismo , Depressão/metabolismo , Masculino , Ratos Wistar , Restrição Física/métodosRESUMO
Previous studies showed that acute restraint stress or transient elevation of glucocorticoid (GC) stress hormones produces emergent changes in both anxiety behavior and dendritic branches in the basolateral amygdala complex (BLA) of rats. In this work, we demonstrate that exposure to environmental enrichment (EE) prevented stress-induced increases in anxiety (emerging 10 days post-stress) in adult rats without blocking stress-induced dendritic branch remodeling in the BLA nor stress-induced enhancement of GC serum levels.
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Plasticidade Neuronal/fisiologia , Estimulação Física/métodos , Estresse Psicológico/fisiopatologia , Tonsila do Cerebelo , Animais , Ansiedade/fisiopatologia , Transtornos de Ansiedade , Complexo Nuclear Basolateral da Amígdala/fisiologia , Dendritos , Meio Ambiente , Masculino , Ratos , Ratos Wistar , Restrição Física/psicologiaRESUMO
The peculiar neurochemical profile of the adolescent brain renders it differently susceptible to several stimuli, including stress and/or drug exposure. Among several stress mediators, nitric oxide (NO) has a role in stress responses. We have demonstrated that adolescent mice are less sensitive to ethanol-induced sensitization than adult mice. The present study investigated whether chronic unpredictable stress (CUS) induces behavioral sensitization to ethanol in adolescent and adult Swiss mice, and investigated the influence of Ca2+-dependent nitric oxide synthase (NOS) activity in the phenomenon. Adolescent and adult mice were exposed to repeated 1.8 g/kg ethanol or CUS and challenged with saline or ethanol. A neuronal nitric oxide synthase (nNOS) inhibitor, 7-nitroindazole (7NI), was administered along with ethanol and CUS to test its effects on behavioral sensitization. Both adolescent and adult mice displayed cross-sensitization between CUS and ethanol in adult mice, with adolescents showing a lower degree of sensitization than adults. nNOS inhibition by 7NI reduced both ethanol sensitization and cross-sensitization. All age differences in the Ca2+-dependent NOS activity in the hippocampus and prefrontal cortex were in the direction of greater activity in adults than in adolescents. Adolescents showed lower sensitivity to cross-sensitization between CUS and ethanol, and the nitric oxide (NO) system seems to have a pivotal role in ethanol-induced behavioral sensitization and cross-sensitization in both adolescent and adult mice.
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Depressores do Sistema Nervoso Central/farmacologia , Etanol/farmacologia , Óxido Nítrico Sintase Tipo I/metabolismo , Estresse Psicológico/metabolismo , Envelhecimento/psicologia , Animais , Comportamento Animal/efeitos dos fármacos , Corticosterona/sangue , Inibidores Enzimáticos/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/enzimologia , Indazóis/farmacologia , Camundongos , Atividade Motora/efeitos dos fármacos , Óxido Nítrico Sintase Tipo I/antagonistas & inibidores , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/enzimologiaRESUMO
We have previously demonstrated that calcium-binding protein S100A8 and myeloid differentiation factor-88 (MyD88) are important mediators of nuclear transcription factor kappa-B (NF-κB) activation in cardiomyocytes and that signalling molecules are involved in the hypertrophic response that is stimulated by thyroid hormones (TH). Angiotensin II (Ang II), the main active peptide of the renin-angiotensin system (RAS), binds to type 1 Ang II receptor (AT1R) and subsequently promotes cardiac hypertrophy and the inflammatory response with NF-κB activation underlying the cardiovascular effects. Considering the amount of evidence that RAS is an important mediator of TH actions on the cardiovascular system, we aimed to investigate whether cardiac expression of NF-κB and upstream associated molecules could be altered in hyperthyroidism, as well as whether AT1R could mediate the effects of TH on cardiac tissue and in cardiomyocytes in culture. Wistar rats were subjected to hyperthyroidism with or without the AT1R blocker losartan. The TH serum levels, haemodynamic parameters and cardiac mass were assessed to confirm the hyperthyroid status. The S100A8, MyD88 and nuclear NF-κB expression levels were increased in the hearts of the hyperthyroid rats, and the losartan treatment attenuated these TH effects. In addition, the cultured cardiomyocytes that had been stimulated with losartan exhibited blunted S100A8 upregulation and NF-κB activation compared with the TH-treated cells. Together, our results suggest that AT1R participates in TH-induced cardiac hypertrophy partly by mediating S100A8, MyD88 and NF-κB activation via TH. These findings indicate the important crosstalk between TH and RAS, highlighting the participation of AT1R in the triggered mechanisms of TH that contribute to the cardiac hypertrophy response.
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Cardiomegalia/metabolismo , Hipertireoidismo/metabolismo , Miócitos Cardíacos/metabolismo , Receptor Tipo 1 de Angiotensina/metabolismo , Hormônios Tireóideos/farmacologia , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Animais , Calgranulina A/genética , Calgranulina A/metabolismo , Cardiomegalia/etiologia , Células Cultivadas , Hipertireoidismo/complicações , Losartan/farmacologia , Masculino , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , NF-kappa B/genética , NF-kappa B/metabolismo , Ratos , Ratos Wistar , Hormônios Tireóideos/sangueRESUMO
Recent studies have evidenced the involvement of inflammation-related pathways to the development of cardiac hypertrophy and other consequences on the cardiovascular system, including the calcium-binding protein S100A8. However, this has never been investigated in the thyroid hormone (TH)-prompted cardiac hypertrophy. Thus, we aimed to test whether S100A8 and related signaling molecules, myeloid differentiation factor-88 (MyD88) and nuclear factor kappa B (NF-ÒB), could be associated with the cardiomyocyte hypertrophy induced by TH. Our results demonstrate that the S100A8/MyD88/NF-ÒB signaling pathway is activated in cardiomyocytes following TH stimulation. The knockdown of S100A8 and MyD88 indicates the contribution of those molecules to cardiomyocyte hypertrophy in response to TH, as evaluated by cell surface area, leucine incorporation assay, and gene expression. Furthermore, S100A8 and MyD88 are crucial mediators of NF-ÒB activation, which is also involved in the hypertrophic growth of TH-treated cardiomyocytes. Supporting the in vitro data, the contribution of NF-ÒB for TH-induced cardiac hypertrophy is confirmed in vivo, by using transgenic mice with cardiomyocyte-specific suppression of NF-ÒB. These data identify a novel pathway regulated by TH that mediates cardiomyocyte hypertrophy. However, the potential role of this new pathway in short and long-term cardiac effects of TH remains to be further investigated. KEY MESSAGES: Inflammation-related signaling is activated by T3 in cardiomyocytes. S100A8 and MyD88 have a crucial role in cardiomyocyte hypertrophy by T3. S100A8 and MyD88 mediate NF-ÒB activation by T3. NF-ÒB contributes to T3-induced cardiac hypertrophy in vitro and in vivo.
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Calgranulina A/genética , Cardiomegalia/genética , Fator 88 de Diferenciação Mieloide/genética , NF-kappa B/genética , Tri-Iodotironina , Animais , Fator Natriurético Atrial/genética , Células Cultivadas , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Peptídeo Natriurético Encefálico/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , Ratos Wistar , Transdução de Sinais , Receptor 4 Toll-Like/genéticaRESUMO
Environmental enrichment (EE) is an experimental animal model that enhances an animal's opportunity to interact with sensory, motor, and social stimuli, compared to standard laboratory conditions. A prominent benefit of EE is the reduction of stress-induced anxiety. The relationship between stress and the onset of anxiety-like behavior has been widely investigated in experimental research, showing a clear correlation with structural changes in the hippocampus and basolateral amygdala (BLA). However, the mechanisms by which EE exerts its protective roles in stress and anxiety remain unclear, and it is not known whether EE reduces the effects of acute stress on animal behavior shortly following the cessation of stress. We found that EE can prevent the emergence of anxiety-like symptoms in rats measured immediately after acute restraint stress (1 h) and this effect is not due to changes in systemic release of corticosterone. Rather, we found that stress promotes a rapid increase in the nuclear translocation of glucocorticoid receptor (GR) in the BLA, an effect prevented by previous EE exposure. Furthermore, we observed a reduction of ERK (a MAPK protein) and CREB activity in the BLA promoted by both EE and acute stress. Finally, we found that EE decreases the expression of the immediate-early gene EGR-1 in the BLA, indicating a possible reduction of neuronal activity in this region. Hyperactivity of BLA neurons has been reported to accompany anxiety-like behavior and changes in this process may be one of the mechanism by which EE exerts its protective effects against stress-induced anxiety.
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Ansiedade/metabolismo , Complexo Nuclear Basolateral da Amígdala/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/fisiologia , Meio Ambiente , Sistema de Sinalização das MAP Quinases/fisiologia , Receptores de Glucocorticoides/fisiologia , Estresse Psicológico/metabolismo , Animais , Ansiedade/genética , Ansiedade/prevenção & controle , Proteína 1 de Resposta de Crescimento Precoce/biossíntese , Proteína 1 de Resposta de Crescimento Precoce/genética , Genes Precoces/fisiologia , Masculino , Aprendizagem em Labirinto/fisiologia , Distribuição Aleatória , Ratos , Ratos Wistar , Estresse Psicológico/genéticaRESUMO
Glucocorticoids are a class of steroid hormones derived from cholesterol. Their actions are mediated by the glucocorticoid and mineralocorticoid receptors, members of the superfamily of nuclear receptors, which, once bound to their ligands, act as transcription factors that can directly modulate gene expression. Through protein-protein interactions with other transcription factors, they can also regulate the activity of many genes in a composite or tethering way. Rapid non-genomic signaling was also demonstrated since glucocorticoids can act through membrane receptors and activate signal transduction pathways, such as protein kinases cascades, to modulate other transcriptions factors and activate or repress various target genes. By all these different mechanisms, glucocorticoids regulate numerous important functions in a large variety of cells, not only in the peripheral organs but also in the central nervous system during development and adulthood. In general, glucocorticoids are considered anti-inflammatory and protective agents due to their ability to inhibit gene expression of pro-inflammatory mediators and other possible damaging molecules. Nonetheless, recent studies have uncovered situations in which these hormones can act as pro-inflammatory agents depending on the dose, chronicity of exposure, and the structure/organ analyzed. In this review, we will provide an overview of the conditions under which these phenomena occur, a discussion that will serve as a basis for exploring the mechanistic foundation of glucocorticoids pro-inflammatory gene regulation in the brain.
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Aging is a multifactorial process associated with an increased susceptibility to neurodegenerative disorders which can be related to chronic inflammation. Chronic inflammation, however, can be characterized by the persistent elevated glucocorticoid (GCs) levels, activation of the proinflammatory transcription factor NF-кB, as well as an increase in cytokines. Interestingly, both NF-кB and cytokines can be even modulated by Glycogen Synthase Kinase 3 beta (GSK-3ß) activity, which is a key protein that can intermediate inflammation and metabolism, once it has a critical role in AKT signaling pathway, and can also intermediate WNT/ß-CATENIN signaling pathway. The aim of this study was to verify age-related changes in inflammatory status, as well as in the AKT and WNT signaling pathways. Results showed an age-related increase in neuroinflammation as indicated by NF-кB activation, TNF-α and GCs increased levels, a decrease in AKT activation and an increase in GSK-3ß activity in both 12- and 24- month old animals. Aging also seems to induce a progressive decrease in canonical WNT/ß-CATENIN signaling pathway once there is a decrease in DVL-2 levels and in the transcription of Axin2 gene. Little is known about the DVL-2 regulation as well as its roles in WNT signaling pathway, but for the first time it was suggested that DVL-2 expression can be changed along aging.