Neuroscience
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Within the nervous system, plasticity mechanisms attempt to stabilize network activity following disruption by injury, disease, or degeneration. Optic nerve injury and age-related diseases can induce homeostatic-like responses in adulthood. We tested this possibility in the thalamocortical (TC) neurons in the dorsolateral geniculate nucleus (dLGN) using patch-clamp electrophysiology, optogenetics, immunostaining, and single-cell dendritic analysis following loss of visual input via bilateral enucleation. ⋯ Analysis of TC neuron dendritic structure from single-cell dye fills revealed a gradual loss of dendrites proximal to the soma, where TC neurons receive the bulk of RG inputs. Finally, analysis of action potential firing demonstrated that TC neurons have increased excitability following enucleation, firing more action potentials in response to depolarizing current injections. Our findings show that degeneration of the retinal axons/optic nerve and loss of RG synaptic inputs induces structural and functional changes in TC neurons, consistent with neuronal attempts at compensatory plasticity in the dLGN.
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Hydrocephalus is characterized by the accumulation of CSF within the cerebral ventricles and the subarachnoid space. Ventricular volume can progressively increase and generate serious damage to the nervous system, with cerebral hypoxia/ischemia as one of the most important factors involved. Hyperbaric oxygen therapy (HBOT) improves oxygen supply to tissues, which can reduce the progression of lesions secondary to ventricular enlargement. ⋯ To assess the response to treatment, behavioral tests were performed such as modified Morris water maze and object recognition, evaluation by transcranial ultrasonography, histology by Hematoxylin-Eosin and Luxol Fast Blue, immunohistochemistry for GFAP, Ki-67, Caspase-3, COX-2, NeuN and SOD1, and biochemical ELISA assay for GFAP and MBP. The results show that the association of treatments exerts neuroprotective effects such as neurobehavioral improvement, preservation of periventricular structures, antioxidant effect, and reduction of damage resulting from ischemia and the neuroinflammatory process. We conclude that HBOT has the potential to be used as an adjuvant treatment to CSF deviation surgery in experimental hydrocephalus.
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Excessive microglia activation occurred in many neurodegenerative diseases. Brefeldin A-inhibited guanine nucleotide-exchange protein 1 (BIG1, ARFGEF1) is involved in cell migration and neurite growth. In the present study, we aimed to explore the effects and potential mechanisms of BIG1 in LPS-mediated neuro-inflammation and migration in BV2 cells. ⋯ Additionally, ChIP-qPCR and Dual-luciferase reporter assay determined that KLF4 binds to the promoter of BIG1, western blot analysis demonstrated that KLF4 could regulate BIG1 positively. In addition, we observed that BIG1 overexpression partly rescued the biological activities of KLF4 silencing in neuro-inflammation and migration in LPS-stimulated BV2 cells. Taken together, BIG1 was mediated by KLF4 regulated LPS-mediated neuro-inflammation and migration in BV2 cells via PI3K/Akt/NF-kB signaling pathway.
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Chronic macrophage activation was implicated as one of the main culprits for chronical, low-grade inflammation which significantly contributes to development of age-related diseases. Microglia as the brain macrophages have been recently implicated as key players in neuroinflammation and neurodegeneration in the aged brain. Microglial cell functions are indispensable in early development, however, activation or senescence of microglia in aging cells may be detrimental. ⋯ By using low doses we could achieve reduction in inflammation circumventing the astrocyte activation. Removal of microglia cells led to decreased expression of the senescence marker p16Ink4a in the aged brain, indicating a relevant contribution of these cells to the expression of this marker and their senescent status in the healthy aging brain. Our results indicate that increased and detrimental brain inflammation in aged murine brain can be impaired by selectively reducing the microglial cell population.