Neuroscience
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Studies using the flanker task have reported that response conflict is detected by the medial frontal cortex (MFC). As a conflict alert system, the MFC shows enhanced functional communication with task-related regions. Previous studies have revealed individual differences in functional connectivity during cognitive task performance. ⋯ However, these findings were only found in the right hemisphere, which may be related to the asymmetrical role of the bilateral PPC in response conflict processing. Furthermore, hierarchical regression analyses revealed that 44% of individual variability in FCz-P4 conflict-induced theta phase synchronization could be explained by variations in axial diffusivity (AD) in the genu of the corpus callosum (gCC). These results demonstrated that structural integrity in the gCC predicts conflict-induced functional connectivity between the MFC and right PPC.
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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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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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Sirtuin 6 (SIRT6), a member of the sirtuin family of NAD(+)-dependent deacetylases, has been shown to produce beneficial effects in myocardial ischemia/reperfusion (I/R). However, the role of SIRT6 in cerebral I/R is largely unclear. In this study, we investigated the effects of SIRT6 overexpression in regulating I/R injury in a mouse cerebral I/R model in vivo and in oxygen-glucose-deprivation/reoxygenation (OGD/R)-stimulated neuro-2a neuroblastoma cells in vitro. ⋯ Moreover, in OGD/R-stimulated neuro-2A cells, SIRT6 overexpression produced similar protective effects to those induced by the antioxidant NAC, but no added benefits were detected when SIRT6 overexpression was used in combination with NAC (P > 0.05). These findings provide evidence that SIRT6 can protect the brain from cerebral I/R injury by suppressing oxidative stress via NRF2 activation. Thus, SIRT6 may serve as a potential therapeutic target for ischemic stroke.
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Neurons of the Grueneberg ganglion (GG) in the anterior nasal region of mice respond to a small set of odorous compounds, including given dimethylpyrazines present in mouse urine. Consequently, mouse pups living in murine colonies are presumably commonly exposed to such GG-activating substances. Since stimulation of the GG elicits alarm and stress reactions in mice, the question arises whether such a GG activation potentially inducing stress could be reduced when pups might rather feel secure in the presence of their mother. ⋯ The attenuated chemosensory responses of GG neurons at 35 °C coincided with a reduced dimethylpyrazine-evoked activation of the glomeruli in the olfactory bulb innervated by GG neurons. The reduction in dimethylpyrazine-evoked GG responses by warm temperatures was positively correlated with exposure time, suggesting that warm temperatures might enhance desensitization processes in GG neurons. In summary, the findings indicate that warm temperatures similar to those in mouse nests in the presence of the dam attenuate GG activation by colony-derived odorants.