Neuroscience
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Astrocytes are major glial cells critical in assisting the function of the central nervous system (CNS), but the functional changes and regulation mechanism of reactive astrocytes are still poorly understood in CNS diseases. In this study, mouse primary astrocytes were cultured, and inflammatory insult was performed to observe functional changes in astrocytes and the involvement of Notch-PI3K-AKT signaling activation through immunofluorescence, PCR, Western blot, CCK-8, and inhibition experiments. Notch downstream signal Hes-1 was clearly observed in the astrocytes, and Notch signal inhibitor GSI dose-dependently decreased the cleaved Notch-l level without an influence on cell viability. ⋯ While an increase in MyD88, NF-кB, and phosphor-NF-кB was confirmed, upregulation of PI3K, AKT, and phosphor-AKT was observed in the activated astrocytes with LPS+IFNγ insult and was reduced by GSI treatment. Inhibitor experiments showed that inhibition of Notch-PI3K-AKT signaling activation reduced the pro-inflammatory cytokine production triggered by LPS+IFNγ inflammatory insult. This study showed that the reactive astrocytes displayed pro-inflammatory adaptability through Notch-PI3K-AKT signaling activation in response to inflammatory stimulation, suggesting that the Notch-PI3K-AKT pathway in reactive astrocytes may serve as a promising target against CNS inflammatory disorders.
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The dorsomedial nucleus of the hypothalamus (DMH) plays an important role in the regulation of energy intake and expenditure. Numerous appetite-regulatory signals present in the DMH, including nitric oxide (NO) and endogenous cannabinoids (eCBs), act to regulate food intake, but whether these signals are involved in regulating high fat food intake remains unknown. We therefore asked whether NO and eCBs, administered alone or in combination, would influence the consumption of high fat food in rats. ⋯ The l-arginine-induced increase in high fat food intake is dependent on NO synthesis, as it is prevented with the NO synthase inhibitor, l-NAME. We also demonstrate that l-arginine increases glutamate transmission onto DMH neurons, an effect that also requires NO synthesis and is abolished with 2-AG. Together, these data indicate that NO acts in the DMH to regulate the consumption of high fat food, possibly by enhancing glutamate signaling at DMH synapses.
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Alzheimer's disease (AD) pathology is characterized by amyloid plaques containing amyloid beta (Aβ) peptides, neurofibrillary tangles containing hyperphosphorylated tau protein, and neuronal loss. In addition, Aβ deposition in brain microvessels, known as cerebral amyloid angiopathy (CAA), increases blood-brain barrier (BBB) permeability and induces vascular dysfunction which aggravates AD pathology. The aim of the present study was to characterize neurovascular dysfunction in the Tg-SwDI mouse model of AD. ⋯ In addition, the TJ protein occludin was decreased in Tg-SwDI mice relative to WT mice, which correlated with an increase in BBB permeability in cultured brain endothelial cells. These findings demonstrated that Tg-SwDI mice exhibit Aβ aggregation that is due, in part, to impaired Aβ clearance driven by both a decrease in P-gp and increase in RAGE protein levels in brain capillaries. Aβ aggregation promotes a decrease in the expression of the TJ protein occludin, and as consequence an increase in BBB permeability.
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NAD(P)+ transhydrogenase (NNT) links redox states of the mitochondrial NAD(H) and NADP(H) via a reaction coupled to proton-motive force across the inner mitochondrial membrane. NNT is believed to be ubiquitously present in mammalian cells, but its expression may vary substantially in different tissues. The present study investigated the tissue distribution and possible roles of NNT in the mouse brain. ⋯ Despite the colocalization between NNT and NO synthase, the S-nitrosation and cGMP levels were independent of the Nnt genotype. Taken together, our results indicated that NNT is unevenly distributed throughout the brain and associated with 5-THergic and NOergic neurons. The lack of NNT led to alterations in brain functions related to mood and motor behavior/performance in aged mice.
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The tumor suppressor RNA-binding motif 5 (RBM5) regulates the expression levels and cassette exon-definition (i.e. splicing) of a select set of mRNAs in a tissue-specific manner. Most RBM5-regulated targets were identified in oncological investigations and frequently involve genes which mediate apoptotic cell death. Little is known about the role of RBM5 in the brain. ⋯ Surprisingly, KO increased the mRNA levels of novel targets including casein kinase 2 alpha prime interacting protein (Csnka2ip/CKT2) - a gene not thought to be expressed in the brain, contrary to findings here. Twenty-two unique splicing events were also detected in KOs including increased block-inclusion of cassette exons 20-22 in regulating synaptic membrane exocytosis 2 (Rims2). In conclusion, here we used genome-wide transcriptomic analysis on healthy and injured RBM5 KO mouse brain tissue to elucidate the first known gene targets of this enigmatic RBP in this CNS.