scholarly journals Minocycline Alleviates Abnormal Phagocytosis of Synapses by Microglia in a Mouse Model of Depression

2021 ◽  
Author(s):  
Qiu-Qin Han ◽  
Shi-Yu Shen ◽  
Xiao-Rong Chen ◽  
Adam Pilot ◽  
Ling-Feng Liang ◽  
...  
Keyword(s):  
Mouse Model ◽  
Microglial Activation ◽  
Functional Brain Imaging ◽  
Behavioral Impairment ◽  
Synaptic Loss ◽  
Neuronal Synapses ◽  
Pathological Conditions ◽  
Treatment Of Depression ◽  
Novel Drugs

Abstract Background Depression is an affective disorder characterized by low mood and loss of interest. So far, the mechanism of antidepressants commonly used in clinical practice has proved problematic, thus it is urgent to gain an updated understanding of the pathogenesis of depression and find potential therapeutic targets. As both functional brain imaging studies and autopsy reports indicated that there is indeed a loss of synapses in depressed patients, it is necessary to explore the mechanism of this process. Methods We firstly investigated the effect of CSDS (a mouse model of depression) on behaviors, synapses, microglia, and phagocytosis of synapses by microglia in mice. Then, to confirm the role of microglia in depression, we used minocycline, a microglial activation inhibitor, to study its effect on behaviors and phagocytosis of synapses in stressed mice. Results Our results show that the expression levels of PSD-95 in the hippocampus of CSDS-induced depression mice are significantly reduced, while the microglia are significantly activated. We co-labeled the synaptic protein PSD-95 with the microglia marker Iba-1, and found that the microglia in the hippocampus of stressed mice contained significantly more PSD-95 engulfed puncta, which revealed that microglia in stressed mice abnormally phagocytized synapses. Moreover, our results indicated that minocycline treatment dampened microglial activation, reduced synaptic loss, alleviated behavioral impairment, and reduced abnormal phagocytosis of synapses by microglia in stressed mice. Conclusions Under depressive pathological conditions, the activated microglia may abnormally engulf neuronal synapses causing synaptic loss. Our findings are important for the discovery of novel drugs for the treatment of depression.

scholarly journals Iron activates microglia and directly stimulates indoleamine-2,3-dioxygenase activity in the N171-82Q mouse model of Huntington’s disease

2019 ◽  
Author(s):  
David W. Donley ◽  
Marley Realing ◽  
Jason P. Gigley ◽  
Jonathan H. Fox
Keyword(s):  
Mouse Model ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Microglial Activation ◽  
Iron Supplementation ◽  
Kynurenine Pathway ◽  
Indoleamine 2,3 Dioxygenase ◽  
Tryptophan Degradation ◽  
Microglial Morphology

AbstractHuntington’s disease (HD) is a neurodegenerative disorder caused by a dominant CAG-repeat expansion in the huntingtin gene. Morphologic activation of microglia is a key marker of neuroinflammation that is present before clinical onset in HD patients. The kynurenine pathway of tryptophan degradation is restricted in part to microglia and is activated in HD, where it contributes to disease progression. Indoleamine-2,3-dioxygenase (IDO) is a microglial enzyme that catalyzes the first step in this pathway. HD brain microglial cells also accumulate iron; however, the role of iron in promoting microglial activation and the kynurenine pathway is unclear. Based on analyses of morphological characteristics of microglia, we showed that HD mice demonstrate an activated microglial morphology compared with controls. Neonatal iron supplementation resulted in additional microglial morphology changes compared with HD controls. Increased microglial activation in iron-supplemented HD mice was indicated by increased soma volume and decreased process length. In our assessment of whether iron can affect the kynurenine pathway, iron directly enhanced the activity of human recombinant IDO1 with an EC50 of 1.24 nM. We also detected elevated microglial cytoplasmic labile iron in N171-82Q HD mice, an increase that is consistent with the cellular location of IDO. We further demonstrated that neonatal iron supplementation, a model for studying the role of iron in neurodegeneration, activates IDO directly in the mouse brain and promotes neurodegeneration in HD mice. Kynurenine pathway metabolites were also modified in HD and by iron supplementation in wild-type mice. These findings indicate that iron dysregulation contributes to the activation of microglia and the kynurenine pathway in a mouse model of HD.

scholarly journals Microglial Activation Contributes to Cognitive Impairments in Rotenone-induced Mouse Parkinson’s Disease Model

2020 ◽  
Author(s):  
Dongdong Zhang ◽  
Sheng Li ◽  
Liyan Hou ◽  
Lu Jing ◽  
Zhengzheng Ruan ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Cognitive Decline ◽  
Passive Avoidance ◽  
Cognitive Performance ◽  
Cognitive Deficits ◽  
Water Maze ◽  
Microglial Activation ◽  
Cognitive Impairments ◽  
Synaptic Loss

Abstract BackgroundCognitive decline occurs frequently in Parkinson’s disease (PD), which greatly decreases the life quality of patients. However, the mechanisms remain to be investigated. Neuroinflammation mediated by over-activated microglia is a common pathological feature in multiple neurological disorders, including PD. This study is designed to explore the role of microglia in cognitive deficits by using rotenone-induced mouse PD model. Methods: To evaluate the role of microglia in rotenone-induced cognitive deficits, PLX3397, an inhibitor of colony-stimulating factor 1 receptor, and minocycline, a widely used antibiotic, were used to deplete or inactivate microglia, respectively. Cognitive performance of mice among groups was detected by morris water maze, objective recognition and passive avoidance tests. Neurodegeneration, synaptic loss, α-synuclein phosphorylation, glial activation and apoptosis were determined by immunohistochemistry, Western blot or immunofluorescence staining. The gene expressions of inflammatory factors and lipid peroxidation were further explored by using RT-PCR and ELISA kits, respectively. ResultsRotenone dose-dependently induced cognitive deficits in mice by showing decreased abilities of novel objective recognition, passive avoidance, as well as morris water maze performance compared with vehicle controls. Rotenone-induced cognitive decline was associated with neurodegeneration, synaptic loss, Ser129-phosphorylation of α-synuclein and microglial activation in the hippocampal and cortical regions of mice. Time course study revealed that rotenone-induced microglial activation preceded neurodegeneration. Interestingly, microglial depletion by PLX3397 or inactivation by minocycline significantly reduced neuronal damage and α-synuclein pathology as well as improved cognitive performance in rotenone-injected mice. Mechanistically, PLX3397 or minocycline attenuated rotenone-induced astroglial activation and production of cytotoxic factors in mice. Reduced lipid peroxidation was also observed in combined PLX3397 or minocycline and rotenone-treated mice compared with rotenone alone group. Finally, microglial depletion or inactivation was found to mitigate rotenone-induced neuronal apoptosis. ConclusionsTaken together, our findings suggested that microglial activation contributed to cognitive impairments in rotenone-induced mouse PD model via neuroinflammation, oxidative stress and apoptosis, providing novel insight for the immunopathogensis of cognitive deficits in PD.

scholarly journals αB-Crystallin Alleviates Endotoxin-Induced Retinal Inflammation and Inhibits Microglial Activation and Autophagy

2021 ◽  
Vol 12 ◽  
Author(s):  
Fangyu Wang ◽  
Zhaoxin Jiang ◽  
Bingsheng Lou ◽  
Fang Duan ◽  
Suo Qiu ◽  
...  
Keyword(s):  
Mouse Model ◽  
Microglial Activation ◽  
Ganglion Cells ◽  
Inflammatory Diseases ◽  
Small Heat Shock Protein ◽  
Bv2 Cells ◽  
Αb Crystallin ◽  
Retinal Inflammation

αB-Crystallin, a member of the small heat shock protein (sHSP) family, plays an immunomodulatory and neuroprotective role by inhibiting microglial activation in several diseases. However, its effect on endotoxin-induced uveitis (EIU) is unclear. Autophagy may be associated with microglial activation, and αB-crystallin is involved in the regulation of autophagy in some cells. The role of αB-crystallin in microglial autophagy is unknown. This study aimed to explore the role of αB-crystallin on retinal microglial autophagy, microglial activation, and neuroinflammation in both cultured BV2 cells and the EIU mouse model. Our results show that αB-crystallin reduced the release of typical proinflammatory cytokines at both the mRNA and protein level, inhibited microglial activation in morphology, and suppressed the expression of autophagy-related molecules and the number of autophagolysosomes in vitro. In the EIU mouse model, αB-crystallin treatment alleviated the release of ocular inflammatory cytokines and the representative signs of inflammation, reduced the apoptosis of ganglion cells, and rescued retinal inflammatory structural and functional damage, as evaluated by optical coherence tomographic and electroretinography. Taken together, these results indicate that αB-crystallin inhibits the activation of microglia and supresses microglial autophagy, ultimately reducing endotoxin-induced neuroinflammation. In conclusion, αB-crystallin provides a novel and promising option for affecting microglial autophagy and alleviating symptoms of ocular inflammatory diseases.

scholarly journals Microglia drive APOE-dependent neurodegeneration in a tauopathy mouse model

2019 ◽  
Vol 216 (11) ◽  
pp. 2546-2561 ◽  
Author(s):  
Yang Shi ◽  
Melissa Manis ◽  
Justin Long ◽  
Kairuo Wang ◽  
Patrick M. Sullivan ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Mouse Model ◽  
Microglial Activation ◽  
Therapeutic Strategies ◽  
Minor Role ◽  
Cell Type ◽  
Chronic Activation ◽  
A Minor ◽  
Immunomodulatory Function

Chronic activation of brain innate immunity is a prominent feature of Alzheimer’s disease (AD) and primary tauopathies. However, to what degree innate immunity contributes to neurodegeneration as compared with pathological protein-induced neurotoxicity, and the requirement of a particular glial cell type in neurodegeneration, are still unclear. Here we demonstrate that microglia-mediated damage, rather than pathological tau-induced direct neurotoxicity, is the leading force driving neurodegeneration in a tauopathy mouse model. Importantly, the progression of ptau pathology is also driven by microglia. In addition, we found that APOE, the strongest genetic risk factor for AD, regulates neurodegeneration predominantly by modulating microglial activation, although a minor role of apoE in regulating ptau and insoluble tau formation independent of its immunomodulatory function was also identified. Our results suggest that therapeutic strategies targeting microglia may represent an effective approach to prevent disease progression in the setting of tauopathy.

scholarly journals Microglial activation contributes to cognitive impairments in rotenone-induced mouse Parkinson’s disease model

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Dongdong Zhang ◽  
Sheng Li ◽  
Liyan Hou ◽  
Lu Jing ◽  
Zhengzheng Ruan ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Cognitive Decline ◽  
Passive Avoidance ◽  
Cognitive Performance ◽  
Cognitive Deficits ◽  
Water Maze ◽  
Microglial Activation ◽  
Cognitive Impairments ◽  
Synaptic Loss

Abstract Background Cognitive decline occurs frequently in Parkinson’s disease (PD), which greatly decreases the quality of life of patients. However, the mechanisms remain to be investigated. Neuroinflammation mediated by overactivated microglia is a common pathological feature in multiple neurological disorders, including PD. This study is designed to explore the role of microglia in cognitive deficits by using a rotenone-induced mouse PD model. Methods To evaluate the role of microglia in rotenone-induced cognitive deficits, PLX3397, an inhibitor of colony-stimulating factor 1 receptor, and minocycline, a widely used antibiotic, were used to deplete or inactivate microglia, respectively. Cognitive performance of mice among groups was detected by Morris water maze, objective recognition, and passive avoidance tests. Neurodegeneration, synaptic loss, α-synuclein phosphorylation, glial activation, and apoptosis were determined by immunohistochemistry and Western blot or immunofluorescence staining. The gene expression of inflammatory factors and lipid peroxidation were further explored by using RT-PCR and ELISA kits, respectively. Results Rotenone dose-dependently induced cognitive deficits in mice by showing decreased performance of rotenone-treated mice in the novel objective recognition, passive avoidance, and Morris water maze compared with that of vehicle controls. Rotenone-induced cognitive decline was associated with neurodegeneration, synaptic loss, and Ser129-phosphorylation of α-synuclein and microglial activation in the hippocampal and cortical regions of mice. A time course experiment revealed that rotenone-induced microglial activation preceded neurodegeneration. Interestingly, microglial depletion by PLX3397 or inactivation by minocycline significantly reduced neuronal damage and α-synuclein pathology as well as improved cognitive performance in rotenone-injected mice. Mechanistically, PLX3397 and minocycline attenuated rotenone-induced astroglial activation and production of cytotoxic factors in mice. Reduced lipid peroxidation was also observed in mice treated with combined PLX3397 or minocycline and rotenonee compared with rotenone alone group. Finally, microglial depletion or inactivation was found to mitigate rotenone-induced neuronal apoptosis. Conclusions Taken together, our findings suggested that microglial activation contributes to cognitive impairments in a rotenone-induced mouse PD model via neuroinflammation, oxidative stress, and apoptosis, providing novel insight into the immunopathogensis of cognitive deficits in PD.

The role of tachykinin 1 in a mouse model of trait anxiety

2007 ◽  
Vol 40 (05) ◽  
Author(s):  
L Czibere ◽  
LA Baur-Jaronowski ◽  
P Weber ◽  
B Pütz ◽  
M Panhuysen ◽  
...  
Keyword(s):  
Mouse Model ◽  
Trait Anxiety

Dietary Carotenoids in Managing Metabolic Syndrome and Role of PPARs in the Process

2020 ◽  
Vol 16 (6) ◽  
pp. 846-853
Author(s):  
Raghunandan Purohith ◽  
Nagendra P.M. Nagalingaswamy ◽  
Nanjunda S. Shivananju
Keyword(s):  
Metabolic Syndrome ◽  
Dietary Intervention ◽  
Bioactive Constituents ◽  
Dietary Antioxidants ◽  
Predisposing Factor ◽  
Beneficial Effects ◽  
Pathological Conditions ◽  
Established Relationship ◽  
Comprehensive Study

Metabolic syndrome is a collective term that denotes disorder in metabolism, symptoms of which include hyperglycemia, hyperlipidemia, hypertension, and endothelial dysfunction. Diet is a major predisposing factor in the development of metabolic syndrome, and dietary intervention is necessary for both prevention and management. The bioactive constituents of food play a key role in this process. Micronutrients such as vitamins, carotenoids, amino acids, flavonoids, minerals, and aromatic pigment molecules found in fruits, vegetables, spices, and condiments are known to have beneficial effects in preventing and managing metabolic syndrome. There exists a well-established relationship between oxidative stress and major pathological conditions such as inflammation, metabolic syndrome, and cancer. Consequently, dietary antioxidants are implicated in the remediation of these complications. The mechanism of action and targets of dietary antioxidants as well as their effects on related pathways are being extensively studied and elucidated in recent times. This review attempts a comprehensive study of the role of dietary carotenoids in alleviating metabolic syndromewith an emphasis on molecular mechanism-in the light of recent advances.

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