Neuroscience
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Profound alterations in both the synaptic and intrinsic membrane properties of neurons that increase the neuronal network excitability are found in epileptic tissue. However, there are still uncertainties regarding the kind of changes in the intrinsic membrane properties occurring during epileptogenesis. Epileptogenesis is typically triggered by the initial brain-damaging insult, and status epilepticus (SE) is one of such insults. ⋯ We found that one day after SE: (1) the intrinsic membrane properties of EC neurons are significantly altered, while the properties of PFC neurons are mostly unchanged; (2) the input resistance and membrane time constant of regular-spiking neurons are reduced due to enhanced leak current; (3) the active membrane properties of neurons are mostly unaffected; and (4) changes in the passive membrane properties diminish the intrinsic neuronal excitability. Therefore, our results suggest that the acute changes in the intrinsic membrane properties of entorhinal neurons following pilocarpine-induced SE do not contribute to network hyperexcitability. In contrast, at the early stage of epileptogenesis, protective homeostatic plasticity of intrinsic membrane properties is observed in the EC; it reduces the neuronal excitability in response to increased network excitability.
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Emerging evidence suggests that acupuncture treatment has anti-oxidative effects that affect cognitive impairment in vascular dementia (VD) rats. In the present study, we aimed to investigate whether thioredoxin-1 (Trx-1)/thioredoxin reductase-1 (TrxR-1) was involved in the beneficial effects of acupuncture. After 2-weeks of acupuncture treatment, Morris water maze (MWM), dihydroethidium (DHE) staining, Nissl staining and TdT-mediated dUTP nick end labeling (TUNEL) staining were used to assess the effects of acupuncture on cognitive function and hippocampal neuronal injury in two-vessel occlusion (2VO) model. ⋯ Acupuncture also up-regulated the expressions of Trx-1 and TrxR-1, increased the activity of TrxR-1, accompanied with inhibiting the activation of the ASK1-JNK/p38 pathway. However, the effects of acupuncture on improving cognitive function, inhibiting oxidative stress and neuron apoptotic damage were blocked by Trx-1siRNA. In conclusion, these findings indicated that acupuncture treatment improved VD though anti-oxidative and anti-apoptotic mechanisms which involved the up-regulations of Trx-1/TrxR-1 and inhibitions of ASK1-JNK/p38 pathway.
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The consequences of stress depend on characteristics of the stressor, including the duration of exposure, severity, and predictability. Exposure of mice to repeated neck restraint has been shown to bidirectionally modulate the potential for long-term potentiation (LTP) in the dentate gyrus (DG) in a manner dependent on the number of restraint repetitions, but the influence of repeated brief neck restraint on electrophysiology of single DG neurons has not yet been investigated. Here, we aimed at finding the effects of 1, 3, 7, 14, or 21 daily neck restraint sessions lasting 10 min on electrophysiological characteristics of DG granule cells as well as excitatory and inhibitory synaptic inputs to these neurons. ⋯ Neck restraint stress impaired cognitive performance in the OLT after three repetitions but improved it after 14 and 21 repetitions. Mice subjected to three neck restraint sessions displayed an increase in the measures of depressive and anxiety-like behaviors, however, prolongation of the exposure to neck restraint resulted in a gradual decline in the intensity of these measures. These data indicate that stress imposed by an increasing number of repeated neck restraint episodes bidirectionally modulates both excitatory synaptic transmission in the DG and cognitive performance in the object location memory task.
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Neural activity varies continually from moment to moment. Such temporal variability (TV) has been highlighted as a functionally specific brain property playing a fundamental role in cognition. We sought to investigate the mechanisms involved in TV changes between two basic behavioral states, namely having the eyes open (EO) or eyes closed (EC) in vivo in humans. ⋯ This reduction is correlated with an increase in energy consumption and with regional GABAA receptor density. This suggests that the modulation of TV by behavioral state involves an increase in overall neural activity that is related to an increased effect from GABAergic inhibition in addition to any excitatory changes. These findings contribute to our understanding of the mechanisms underlying activity variability in the human brain and its control.
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The aims of this study were to examine the levels of serum and exosomal miR-137, miR-155 and miR-223, three neuroinflammation-related miRNAs, in dementia patients and to explore the value of these miRNAs for the diagnosis and prognostic evaluation of dementia. Thirty-two patients with dementia were enrolled, and sixteen volunteers without dementia served as controls. Serum exosomes were isolated by precipitation with ExoQuick and characterized by western blotting, nanoparticle-tracking analysis and immunofluorescence microscopy. ⋯ The level of miR-223 was significantly correlated with Mini-Mental State Examination (MMSE) scores, Clinical Dementia Rating (CDR) scores, magnetic resonance spectroscopy (MRS) spectral ratios and serum concentrations of IL-1β, IL-6, TNF-α, and CRP. The diagnostic utility of exosomal miR-233 was evaluated by the area under the receiver operating characteristic (ROC) curve, and the area under the curve (AUC) was 0.875. This study suggests that serum exosomal miR-223 is a promising biomarker for diagnosing dementia and evaluating the progression of disease.