Navegando por Palavras-chave "Chronic stress"
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- ItemSomente MetadadadosChronic unpredictable stress exacerbates lipopolysaccharide-induced activation of nuclear factor-kappa B in the frontal cortex and hippocampus via glucocorticoid secretion(Soc Neuroscience, 2006-04-05) Munhoz, Carolina Demarchi; Lepsch, Lucilia Brochado; Kawamoto, Elisa Mitiko; Malta, Marília Brinati; Lima, Larissa de Sá; Avellar, Maria Christina Werneck [UNIFESP]; Sapolsky, Robert M.; Scavone, Cristoforo; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Stanford UnivAlthough the anti-inflammatory actions of glucocorticoids (GCs) are well established in the periphery, these stress hormones can increase inflammation under some circumstances in the brain. the transcription factor nuclear factor-kappa B (NF-kappa B), which is inhibited by GCs, regulates numerous genes central to inflammation. in this study, the effects of stress, GCs, and NMDA receptors on lipopolysaccharide (LPS)-induced activation of NF-kappa B in the brain were investigated. One day after chronic unpredictable stress (CUS), nonstressed and CUS rats were treated with saline or LPS and killed 2 h later. CUS potentiated the increase in LPS-induced activation of NF-kappa B in frontal cortex and hippocampus but not in the hypothalamus. This stress effect was blocked by pretreatment of rats with RU-486, an antagonist of the GC receptor. MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate], an NMDA receptor antagonist, also reduced the effect of LPS in all three brain regions. However, the combined antagonism of both GC and NMDA receptors produced no further reduction in NF-kappa B activation when compared with the effect of each treatment alone. Our results indicate that stress, via GC secretion, can increase LPS-induced NF-kappa B activation in the frontal cortex and hippocampus, agreeing with a growing literature demonstrating proinflammatory effects of GCs.
- ItemAcesso aberto (Open Access)Efeitos do estresse agudo e crônico sobre o sistema serotonérgico de diferentes subnúcleos do núcleo dorsal da rafe(Universidade Federal de São Paulo (UNIFESP), 2015-03-03) Lopes, Danielle Abreu [UNIFESP]; Viana, Milena de Barros [UNIFESP]; http://lattes.cnpq.br/3053794724319601; http://lattes.cnpq.br/7678648200199762; Universidade Federal de São Paulo (UNIFESP)The concept of stress is based on the observation that different types of stimuli (external or internal) that threaten homeostasis induce a set of bodily changes, called "general adaptation syndrome". The term stimulus or stressor corresponds to events or circumstances that are perceived as aversive by the individual, generating the so-called stress response or stress condition, involving visceral, neuroendocrine and behavioral responses. This set of responses aim at maintaining the body homeostasis / allostasis, and by themselves are not pathological. However, when the aversive stimulation occurs for a prolonged period or exceeds the body's ability to maintain homeostasis / allostasis, stress can cause pathological sequelae. One of the major neurotransmitter systems that appear to be dysregulated in stress-related disorders such as anxiety and depression is the serotonergic system, originating from the dorsal raphe nucleus (DRN). In previous studies, we verified that exposure to acute restraint and to unpredictable chronic mild stress (UCMS) increased anxiety-related behavior and Fos-immunoreactivity in different brain areas, including the dorsal raphe (DR). Since, it has been shown that the DR is composed by distinct subpopulations of serotonergic and non-serotonergic neurons, the present study investigated the pattern of activation of these different subnuclei of the region in response to acute and chronic stressors. Male Wistar rats were either unstressed or exposed to acute restraint or to the UCMS procedure for two weeks and, subsequently, analyzed for Fos protein-immunoreactivity (Fos-ir), tryptophan hidroxilase enzyme immunoreactivity (TrpOH-ir) and double-labeling (Fos/TrpOH-ir) in serotonergic cells of the DR. For comparison reasons, the median raphe (MR) nucleus was also evaluated. Results showed that the UCMS procedure increased Fos-ir and the number of double-labeled neurons in the mid-rostral subdivision of the dorsal part of the DR and in the mid-caudal region of the lateral wings. In this last region, there was also a significant increase in the number of tryptophan hydroxylase immunoreactive cells. Although both acute restraint and UCMS exposure increased Fos-ir in the MR, only acute restraint increased double immunolabeling in this region. This data indicates that acute restraint and UCMS exposure differently activate the DR and the MR, corroborating the idea that these regions play distinct roles in the regulation of stressrelated responses.
- ItemSomente MetadadadosMultiple trial inhibitory avoidance acquisition and retrieval are resistant to chronic stress(Elsevier Science Bv, 2018) Raya, J. [UNIFESP]; Girardi, C. E. N. [UNIFESP]; Esumi, L. A. [UNIFESP]; Ferreira, L. B. T. [UNIFESP]; Hipolide, D. C. [UNIFESP]Chronic mild stress (CMS) is a widely accepted animal model relevant to depression that among other consequences, is chiefly known to induce anhedonia, often assessed as decreased preference for sucrose solution. CMS is also known to affect cognition, particularly memory tasks. In this study we have employed the multiple trial inhibitory avoidance memory task (MTIA) to assess CMS effects on memory acquisition and retrieval. MTIA consists of repeated exposures to the unconditioned stimulus until a learning criterion is reached. Wistar rats underwent CMS for 5 weeks, and sucrose consumption was assessed once a week. At the end of CMS, animals were evaluated in the MTIA task. Overall decreased sucrose solution preference was highly variable. Further analyses showed that a subset of animals expressed resilience while another subset was sensitive to stress. CMS did not affect the number of acquisition sessions before reaching criterion or retrieval latency of MTIA task in neither sensitive nor resilient groups. Although tasks that assess learning ability in animal models relevant to depression indicate cognitive deficits, the ability to learn the association between compartment crossing and the aversive electric foot shock, which is strongly dependent on emotional aspects, was intact.