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AGE-RELATED COGNITIVE IMPAIRMENT IS ASSOCIATED WITH LONG-TERM NEUROINFLAMMATION AND OXIDATIVE STRESS IN A MOUSE MODEL OF EPISODIC SYSTEMIC INFLAMMATION
Estresse Oxidativo
Comprometimento cognitivo relacionado à idade
Inflamação sistêmica episódica
Oxidative stress
Episodic systemic inflammation
Age-related cognitive impairment
Author
Affilliation
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Imunofarmacologia. Rio de Janeiro, RJ, Brasil.
Universidade Federal do Rio de Janeiro. Instituto de Bioquímica Médica Leopoldo de Meis. Rio de Janeiro, RJ, Brasil.
Pasteur Institute. Human Histopathology and Animal Models. Paris, France.
Universidade Federal do Rio de Janeiro. Instituto de Bioquímica Médica Leopoldo de Meis. Rio de Janeiro, RJ, Brasil.
Universidade Federal do Rio de Janeiro. Instituto de Bioquímica Médica Leopoldo de Meis. Rio de Janeiro, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Imunofarmacologia. Rio de Janeiro, RJ, Brasil.
Pasteur Institute. Human Histopathology and Animal Models. Paris, France.
Pasteur Institute. Human Histopathology and Animal Models. Paris, France.
Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil / Instituto IDÓR de Pesquisa e Educação. Rio de Janeiro, RJ, Brasil.
Universidade Federal do Rio de Janeiro. Instituto de Bioquímica Médica Leopoldo de Meis. Rio de Janeiro, RJ, Brasil.
Pasteur Institute. Human Histopathology and Animal Models. Paris, France.
Universidade Federal do Rio de Janeiro. Instituto de Bioquímica Médica Leopoldo de Meis. Rio de Janeiro, RJ, Brasil.
Universidade Federal do Rio de Janeiro. Instituto de Bioquímica Médica Leopoldo de Meis. Rio de Janeiro, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Imunofarmacologia. Rio de Janeiro, RJ, Brasil.
Pasteur Institute. Human Histopathology and Animal Models. Paris, France.
Pasteur Institute. Human Histopathology and Animal Models. Paris, France.
Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil / Instituto IDÓR de Pesquisa e Educação. Rio de Janeiro, RJ, Brasil.
Abstract
Background: Microglia function is essential to maintain the brain homeostasis. Evidence shows that aged microglia are primed and show exaggerated response to acute inflammatory challenge. Systemic inflammation signals to the brain inducing changes that impact cognitive function. However, the mechanisms involved in age-related cognitive decline associated to episodic systemic inflammation are not completely understood. The aim of this study was to identify neuropathological features associated to age-related cognitive decline in a mouse model of episodic systemic inflammation. Methods: Young and aged Swiss mice were injected with low doses of LPS once a week for 6 weeks to induce episodic systemic inflammation. Sickness behavior, inflammatory markers, and neuroinflammation were assessed in different phases of systemic inflammation in young and aged mice. Behavior was evaluated long term after episodic systemic inflammation by open field, forced swimming, object recognition, and water maze tests. Results: Episodic systemic inflammation induced systemic inflammation and sickness behavior mainly in aged mice. Systemic inflammation induced depressive-like behavior in both young and aged mice. Memory and learning were significantly affected in aged mice that presented lower exploratory activity and deficits in episodic and spatial memories, compared to aged controls and to young after episodic systemic inflammation. Systemic inflammation induced acute microglia activation in young mice that returned to base levels long term after episodic systemic inflammation. Aged mice presented dystrophic microglia in the hippocampus and entorhinal cortex at basal level and did not change morphology in the acute response to SI. Regardless of their dystrophic microglia, aged mice produced higher levels of pro-inflammatory (IL-1β and IL-6) as well as pro-resolution (IL-10 and IL-4) cytokines in the brain. Also, higher levels of Nox2 expression, oxidized proteins and lower antioxidant defenses were found in the aged brains compared to the young after episodic systemic inflammation. Conclusions: Our data show that aged mice have increased susceptibility to episodic systemic inflammation. Aged mice that showed cognitive impairments also presented higher oxidative stress and abnormal production of cytokines in their brains. These results indicate that a neuroinflammation and oxidative stress are pathophysiological mechanisms of age-related cognitive impairments.
Keywords in Portuguese
NeuroinflamaçãoEstresse Oxidativo
Comprometimento cognitivo relacionado à idade
Inflamação sistêmica episódica
Keywords
NeuroinflammationOxidative stress
Episodic systemic inflammation
Age-related cognitive impairment
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