Neuroscience
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Neuroglobin (Ngb) is a member of the globin family of respiratory proteins, which was recently observed in many neurons of the auditory pathways. Up to now, however, nothing was known about the role of Ngb in hearing processes. We therefore studied auditory function by recording distortion-product otoacoustic emissions (DPOAE) and auditory brainstem responses (ABRs) in wild-type (C57BL/6N) and Ngb-knockout mice. ⋯ While ABR amplitudes were similar in both groups before noise overexposure, four weeks after trauma a moderate but statistically significant decrease of the latest peak-to-peak response amplitude (originating in the inferior colliculus) was observed in KO mice. Our results suggest that the lack of Ngb, at least in the model used in the present study, results in only marginal deficits in hearing ability. A putative functional role of Ngb in the efferent system warrants further studies.
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According to the theories of neural plasticity and neural efficiency, professional skill training improves performance by strengthening the underlying neural mechanisms. Therefore, subjects trained professionally may exhibit changes in resting-state neurophysiological characteristics closely related to performance. ⋯ There was also a significant linear correlation between the characteristic path length of the resting-state theta band brain network and shooting performance (r = 0.56, P < 0.0005). This study identifies potential neural mechanisms underlying successful shooting and a new method for predicting and evaluating performance based on EEG characteristics.
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Repeated use of opioids can lead to the development of analgesic tolerance and dependence. Additionally, chronic opioid exposure can cause a paradoxical emergence of heightened pain sensitivity to noxious stimuli, termed hyperalgesia, which may drive continued or escalated use of opioids to manage worsening pain symptoms. Opioid-induced hyperalgesia has traditionally been measured in rodents via reflex-based assays, including the von Frey method. ⋯ We next investigated individual relationships between pain avoidance-like behavior and alterations in protein phosphorylation in central motivation-related brain areas. We discovered that pain avoidance-like behavior was significantly correlated with alterations in phosphorylation status of protein kinases (ERK, CaMKII), transcription factors (CREB), presynaptic markers of neurotransmitter release (Synapsin), and the rate-limiting enzyme for dopamine synthesis (TH) across specific brain regions. Our findings suggest that alterations in phosphorylation events in specific brain centers may support cognitive/motivational responses to avoid pain.
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The aim of this study is to investigate the effect of ketogenic metabolism, induced by different diet interventions, on histone acetylation and its potential antioxidant capacity to injured spinal cord tissue in rats. 72 male Sprague-Dawley rats were randomly divided into 4 groups, fed with ketogenic diet (KD), every other day fasting (EODF), every other day ketogenic diet (EODKD) and standard diet (SD) respectively for 2 weeks. β-Hydroxybutyrate (βOHB) concentration was measured both in serum and cerebrospinal fluid (CSF). C5 spinal cord tissue was harvested before, at 3 h and 24 h after injury for analysis of HDAC activity, histone acetylation and oxidative makers. All three dietary interventions resulted in a significant increase of βOHB level in both serum and CSF, and inhibited HDAC activity by 31-43% in spinal cord. ⋯ Anti-oxidative stress genes Foxo3a and Mt2 and related proteins, such as mitochondrial superoxide dismutase (SOD), FOXO3a, catalase were increased in dietary intervention groups. After SCI, high ketogenic metabolism demonstrated significant reduction of the expression of lipid peroxidation factors malondialdehyde (MDA), and this might contribute to the reported neuroprotection of the spinal cord from oxidative damage possibly mediated by increasing SOD. The result of this study suggested that by inhibiting HDAC activity and modifying related gene transcription, ketogenic metabolism, induced by KD, EODF or EODKD, might reduce oxidative damage in the spinal cord tissue after acute injury.
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Although inflammation-induced peripheral sensitization oftentimes resolves as an injury heals, this sensitization can be pathologically maintained and contribute to chronic inflammatory pain. Numerous inflammatory mediators increase the production of reactive oxygen (ROS) and nitrogen species (RNS) during inflammation and in animal models of chronic neuropathic pain. Our previous studies demonstrate that ROS/RNS and subsequent DNA damage mediate changes in neuronal sensitivity induced by anticancer drugs and by ionizing radiation in sensory neurons, thus we investigated whether inflammation and inflammatory mediators also could cause DNA damage in sensory neurons and whether that DNA damage alters neuronal sensitivity. ⋯ Genetically enhancing the expression of the DNA repair enzyme, apurinic/apyrimidinic endonuclease (APE1) or treatment with a small-molecule modulator of APE1 DNA repair activity, both which enhance DNA repair, attenuated DNA damage and the changes in neuronal sensitivity elicited by LPS or MCP-1. In conclusion, our studies demonstrate that inflammation or exposure to inflammatory mediators elicits DNA damage in sensory neurons. By enhancing DNA repair, we demonstrate that this DNA damage mediates the alteration of neuronal function induced by inflammatory mediators in peptidergic sensory neurons.