Neuroscience
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Microglial cells are the pivotal immune cells of the central nervous system. Adult microglia cells under physiological conditions are in a ramification state with extensively branched processes. Upon disease stimulation, they retract their processes and become activated. ⋯ Mechanistic studies confirmed that the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signal, extracellular signal-regulated kinase 1/2 (ERK1/2) or small RhoGTPase activation mediated the effect of CC on microglial shape change based on the following observations: (i) CC induced a significant activation of the small RhoGTPase Rac1 and Cdc42; (ii) CC promoted the phosphorylation of ERK1/2 and Akt; (iii) inhibition of Rac1, Cdc42, ERK1/2, or the PI3K-Akt signal abolished the effect of CC on microglial shape change. These signal mechanisms were also ascertained in primary microglia. Our results explore a potential agent that promotes microglial ramification, and provide an alternative explanation for the neuroprotective effects of CC in various disease models such as brain ischemia and subarachnoid hemorrhage.
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Sigma-1 receptor (S1R) is a unique pluripotent modulator of living systems and has been reported to be associated with a number of neurological diseases including pathological pain. Intrathecal administration of S1R antagonists attenuates the pain behavior of rodents in both inflammatory and neuropathic pain models. However, the S1R localization in the spinal cord shows a selective ventral horn motor neuron distribution, suggesting the high likelihood of S1R in the dorsal root ganglion (DRG) mediating the pain relief by intrathecally administered drugs. ⋯ Using immuno-electron microscopy, we showed that S1R is detected in the nuclear envelope and endoplasmic reticulum (ER) of DRG cells. In contrast to other cells, S1R is also located directly at the plasma membrane of the DRG neurons. The presence of S1R in the nuclear envelope of all DRG neurons suggests an exciting potential role of S1R as a regulator of neuronal nuclear activities and/or gene expression, which may provide insight toward new molecular targets for modulating nociception at the level of primary afferent neurons.
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For years, the prevailing hypothesis for Alzheimer's Disease (AD) has proposed a mechanism by which deposition of amyloid-beta (Aβ) in the brain is independent of tau-pathologies and cognitive decline. However, despite extensive research on the disease, the mechanisms underlying the etiology of tau-pathology remain unknown. Previous research in our lab has shown that imatinib methanesulfonate (IM) blocks the peripheral production of Aβ in response to LPS, thereby preventing the buildup of Aβ in the hippocampus, and rescuing the cognitive dysfunction that normally follows. ⋯ In addition, 7days of LPS-induced inflammation and Aβ production also leads to elevated total tau protein expression. Our results may provide support for the hypothesis that enhanced expression of tau following LPS administration is a protective measure by hippocampal neurons to compensate for the loss of the microtubule-stabilizing protein due to phosphorylation. More importantly, our results support the hypothesis that blocking the production of Aβ that follows inflammation also leads to reduced tau phosphorylation, lending credence to a model in which Aβ initiates tau phosphorylation.
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Songbirds, like humans, learn vocalizations and their striatum recruits new neurons in adulthood. Injury in striatal vocal nucleus Area X, involved in song learning and production in songbirds, is followed by massive regeneration. The newborn neurons arise from the subventricular zone (SVZ) rich in dopamine D3 receptors (D3Rs). ⋯ Moreover, lesion alone prolonged the song duration and this may be facilitated by D3Rs in RA. Parallel lesion and stimulation of D3Rs prolonged it even more, while blocking of D3Rs abolished the lesion-induced effect. These data suggest that D3R stimulation after striatal injury accelerates the striatal recovery and can cause behavioral alterations.
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Xylene and its derivatives are raw materials widely used in industry and known to be toxic to animals. However, the mechanism underlying the neurotoxicity of para-xylene (PX) to the central nervous system (CNS) in vivo is less clear. Here, we exposed Xenopus laevis tadpoles to sub-lethal concentrations of PX during the critical period of brain development to determine the effects of PX on Xenopus development and visual behavior. ⋯ In particular, the increase in apoptotic cells in PX-treated brains was also inhibited by GA treatment. These effects indicate that epigenetic regulation plays a key role in PX-induced apoptosis and animal behavior. In an effort to characterize the neurotoxic effects of PX on brain development and behavior, these results suggest that the neurotoxicity of PX requires further evaluation regarding the safety of commercial and industrial uses.