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Neuroinflammation is initiated through microglial activation and cytokine release which can be induced through lipopolysaccharide treatment (LPS) leading to a transcriptional cascade culminating in the differential expression of target proteins. These differentially expressed proteins can then be packaged into extracellular vesicles (EVs), a form of cellular communication, further propagating the neuroinflammatory response over long distances. Despite this, the EV proteome in the brain, following LPS treatment, has not been investigated. Brain tissue and brain derived EVs (BDEVs) isolated from the cortex of LPS‐treated mice underwent thorough characterisation to meet the minimal information for studies of extracellular vesicles guidelines before undergoing mass spectrometry analysis to identify the differentially expressed proteins. Fourteen differentially expressed proteins were identified in the LPS brain tissue samples compared to the controls and 57 were identified in the BDEVs isolated from the LPS treated mice compared to the controls. This included proteins associated with the initiation of the inflammatory response, epigenetic regulation, and metabolism. These results allude to a potential link between small EV cargo and early inflammatory signalling. [ABSTRACT FROM AUTHOR]

Neuroinflammation is an underlying feature of neurodegenerative conditions, often appearing early in the aetiology of a disease. Microglial activation, a prominent initiator of neuroinflammation, can be induced through lipopolysaccharide (LPS) treatment resulting in expression of the inducible form of nitric oxide synthase (iNOS), which produces nitric oxide (NO). NO post‐translationally modifies cysteine thiols through S‐nitrosylation, which can alter function of the target protein. Furthermore, packaging of these NO‐modified proteins into extracellular vesicles (EVs) allows for the exertion of NO signalling in distant locations, resulting in further propagation of the neuroinflammatory phenotype. Despite this, the NO‐modified proteome of activated microglial EVs has not been investigated. This study aimed to identify the protein post‐translational modifications NO signalling induces in neuroinflammation. EVs isolated from LPS‐treated microglia underwent mass spectral surface imaging using time of flight‐secondary ion mass spectrometry (ToF‐SIMS), in addition to iodolabelling and comparative proteomic analysis to identify post‐translation S‐nitrosylation modifications. ToF‐SIMS imaging successfully identified cysteine thiol side chains modified through NO signalling in the LPS treated microglial‐derived EV proteins. In addition, the iodolabelling proteomic analysis revealed that the EVs from LPS‐treated microglia carried S‐nitrosylated proteins indicative of neuroinflammation. These included known NO‐modified proteins and those associated with LPS‐induced microglial activation that may play an essential role in neuroinflammatory communication. Together, these results show activated microglia can exert broad NO signalling changes through the selective packaging of EVs during neuroinflammation. [ABSTRACT FROM AUTHOR]

Prion diseases, also known as transmissible spongiform encephalopathies, are rare, progressive, and fatal neurodegenerative disorders, which are caused by the accumulation of the misfolded cellular prion protein (PrPC). The resulting cytotoxic prion species, referred to as the scrapie prion isoform (PrPSc), assemble in aggregates and interfere with neuronal pathways, ultimately rendering neurons dysfunctional. As the prion protein physiologically interacts with redox-active metals, an altered redox balance within the cell can impact these interactions, which may lead to and facilitate further misfolding and aggregation. The initiation of misfolding and the aggregation processes will, in turn, induce microglial activation and neuroinflammation, which leads to an imbalance in cellular redox homeostasis and enhanced redox stress. Potential approaches for therapeutics target redox signalling, and this review illustrates the pathways involved in the above processes. [ABSTRACT FROM AUTHOR]

Exercise has been shown to be beneficial in reducing symptoms of affective disorders and to increase the expression of brain‐derived neurotrophic factor (BDNF). The BDNF Val66Met polymorphism is associated with reduced activity‐dependent BDNF release and increased risk for anxiety and depression. Male and female Val66Met rats were given access to running wheels from 3 weeks of age and compared to sedentary controls. Anxiety‐ and depression‐like behaviors were measured in adulthood using the elevated plus maze (EPM), open field (OF), and forced swim test (FST). Expression of BDNF and a number of stress‐related genes, the glucocorticoid receptor (Nr3c1), serum/glucocorticoid‐regulated kinase 1 (Sgk1), and FK506 binding protein 51 (Fkbp5) in the hippocampus were also measured. Rats given access to running wheels developed high levels of voluntary exercise, decreased open‐arm time on the EPM and center‐field time in the OF, reduced overall exploratory activity in the open field, and increased immobility time in the FST with no differences between genotypes. Chronic exercise induced a significant increase in Bdnf mRNA and BDNF protein levels in the hippocampus with some of these effects being genotype specific. Exercise decreased the expression of Nr3c1 and Sgk1, but increased the expression of Fkbp5. These results suggest that chronic running‐wheel exercise from adolescence increased anxiety and depression‐like phenotypes in adulthood, independent of BDNF Val66Met genotype. Further studies are required to confirm that increased indices of anxiety‐like behavior are independent from reduced overall locomotor activity. [ABSTRACT FROM AUTHOR]

Exposure to stressful stimuli causes activation of the hypothalamic-pituitary-adrenal axis which rapidly releases high concentrations of glucocorticoid stress hormones, resulting in increased cellular metabolism and spontaneous oxygen and nitrogen radical formation. High concentrations of nitrogen radicals, including nitric oxide, cause damage to cellular proteins in addition to inhibiting components of the mitochondrial transport chain, leading to cellular energy deficiency. During stress exposure, pharmacological inhibition of nitric oxide production reduces indicators of anxiety- and depressive-like behavior in animal models. Therefore, the purpose of this review is to present an overview of the current literature on stress-evoked changes in the nitrergic system, particularly within neural tissue. [ABSTRACT FROM AUTHOR]