Neuroscience
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The tumor necrosis factor like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible 14 (Fn14), mediate inflammation and neuronal apoptosis in cerebral edema, ischemic stroke and multiple sclerosis. The downstream effectors and pathways linked to TWEAK-Fn14 signaling are strongly implicated in the pathology of Parkinson's disease (PD), thus indicating a putative role for TWEAK/Fn14 signaling in PD neurodegeneration. Using the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model, we aimed to determine whether genetic ablation or pharmacologic mitigation of the TWEAK protein and its Fn14 receptor affected substantia nigra and striatum Parkinsonian pathology. ⋯ Mitigating the effects of endogenous TWEAK protein using neutralizing antibody did affect MPTP-mediated neurotoxicity in the substantia nigra using the sub-acute model of MPTP (30mg/kg i.p. over five consecutive days). Neither TWEAK nor Fn14 genetic ablation led to attenuation of MPTP-toxicity in the acute model. These findings suggest that TWEAK signaling might be an aspect of MPTP-mediated neuropathology and be involved in the overall neurodegenerative pathology of PD.
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Activation of P2X7 receptor (P2X7R), a purinergic receptor, expressed by neurons is well-known to induce their death, but whether or not their sensitivity to ATP depends on its expression levels remains unclear. Here, we examined the effect of the expression level of P2X7Rs on cell viability using pure neuron cultures, co-cultures with astrocytes derived from SJL- and ddY-strain mice, and mouse P2X7R-expressing HEK293T cell systems. Treatment of pure neuron cultures with 5mM ATP for 2h, followed by 3-h incubation in fresh medium, resulted in death of both types of neurons, and their death was prevented by administration of P2X7R-specific antagonists. ⋯ The ATP-induced neuronal death was greater for SJL-neurons than for ddY-ones, this being correlated with the expression level of P2X7R in them, and the same results were obtained for the HEK293T cell systems. Co-culture of neurons with astrocytes increased the ATP-induced neuronal death compared to the case of pure neuron cultures. Overall, we reveal that neuronal vulnerability to ATP depends on the expression level of P2X7R, and co-existence of astrocytes exacerbates ATP-induced neuronal death.
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Microglia have multiple functions in regulating homeostasis in the central nervous system (CNS), and microglial inflammation is thought to play a role in the etiology of the neurodegenerative diseases. When endogenous or exogenous stimuli trigger disorders in microenvironmental homeostasis in CNS, microglia critically determine the fate of other neural cells. ⋯ Though the interaction between autophagy and macrophages has been reported and reviewed in length, the role of autophagy in microglia has yet to be reviewed. Herein, we will highlight recent advances on the emerging role of autophagy in microglia, focusing on the regulation of autophagy during microglial inflammation, and the possible mechanism involved.
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Binge eating is defined by the consumption of an excessive amount of food in a short time, reflecting a form of hedonic eating that is not necessarily motivated by caloric need. Foods consumed during a binge are also often high in fat and/or sugar. Ghrelin, signaling centrally via the growth-hormone secretagogue receptor (GHSR), stimulates growth hormone release and appetite. ⋯ GHSR KO mice also had reduced activation of the nucleus accumbens shell, but not core, following HFD consumption. These data support the ability of INT HFD in mice to induce a binge-compensate pattern of intake that emulates select components of binge eating in humans. There also appears to be a role for GHSR signaling in driving HFD consumption under these conditions, potentially via mediation of reward-related circuitry.
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The aim of this study was to investigate the role of monoamine neurotransmitters on the severity of experimental autoimmune encephalomyelitis (EAE) in obese mice. EAE was induced in mice with normal diets (ND-EAE) and obese mice with high-fat diets (HFD-EAE) through the immune response to myelin oligodendrocyte glycoprotein (MOG) (35-55). The levels of dopamine (DA), serotonin (5-HT) and their metabolites in different anatomical brain regions were measured by high-performance liquid chromatography. ⋯ The cytokine levels in the plasma, tissues, and cultured splenocytes were found to be significantly altered in EAE mice compared with control mice. Moreover, HFD-EAE mice exhibited significantly higher MMP-9 activity and lower IL-4 levels than ND-EAE mice and were significantly correlated with brain 5-HT levels. In conclusion, the increased 5-HT levels in the brain significantly correlated with MMP-9 activity and IL-4 levels play an important role in the exacerbation of disease severity in HFD-EAE mice.