Peroxynitrite alters GABAergic synaptic transmission in immature rat hippocampal slices

Systematic Analysis of RNA Expression Profiles in Different Ischemic Cortices in MCAO Mice

The prognosis of ischemic stroke patients is highly associated with the collateral circulation. And the competing endogenous RNAs (ceRNAs) generated from different compensatory supply regions may also involve in the regulation of ischemic tissues prognosis. In this study, we found the apoptosis progress of ischemic neurons in posterior circulation-supplied regions (close to PCA, cortex2) was much slower than that in anterior circulation-supplied territory (close to ACA, cortex1) in MCAO-3-h mice. Using the RNA sequencing and functional enrichment analysis, we analyzed the difference between RNA expression profile in cortex1 and cortex2 and the related biological processes. The results indicated that the differential expressed ceRNAs in cortex1 were involved in cell process under acute injury, while the differential expressed ceRNAs in cortex2 was more likely to participate in long-term injury and repair process. Besides, by establishing the miRNA-ceRNA interaction network we further sorted out two specifically distributed miRNAs, namely mmu-miR446i-3p (in cortex1) and mmu-miR3473d (in cortex2). And the specifically increased mmu-miR3473d in cortex2 mainly involved the angiogenesis and cell proliferation after ischemic stroke, which may be the critical reason for the longer therapeutic time window in cortex2. In conclusion, the present study reported the specific changes of ceRNAs in distinct compensatory regions potentially involved in the evolution of cerebral ischemic tissues and the unbalance prognosis after stroke. It provided more evidence for the collateral compensatory effects on patients' prognosis and carried out the new targets for the ischemic stroke therapy.

Genetic and molecular basis of epilepsy-related cognitive dysfunction

Epilepsy is a common neurological disease characterized by recurrent seizures. About 70 million people were affected by epilepsy or epileptic seizures. Epilepsy is a complicated complex or symptomatic syndromes induced by structural, functional, and genetic causes. Meanwhile, several comorbidities are accompanied by epileptic seizures. Cognitive dysfunction is a long-standing complication associated with epileptic seizures, which severely impairs quality of life. Although the definitive pathogenic mechanisms underlying epilepsy-related cognitive dysfunction remain unclear, accumulating evidence indicates that multiple risk factors are probably involved in the development and progression of cognitive dysfunction in patients with epilepsy. These factors include the underlying etiology, recurrent seizures or status epilepticus, structural damage that induced secondary epilepsy, genetic variants, and molecular alterations. In this review, we summarize several theories that may explain the genetic and molecular basis of epilepsy-related cognitive dysfunction.

Nitric Oxide-Mediated Posttranslational Modifications: Impacts at the Synapse

Nitric oxide (NO) is an important gasotransmitter molecule that is involved in numerous physiological processes throughout the nervous system. In addition to its involvement in physiological plasticity processes (long-term potentiation, LTP; long-term depression, LTD) which can include NMDAR-mediated calcium-dependent activation of neuronal nitric oxide synthase (nNOS), new insights into physiological and pathological consequences of nitrergic signalling have recently emerged. In addition to the canonical cGMP-mediated signalling, NO is also implicated in numerous pathways involving posttranslational modifications. In this review we discuss the multiple effects of S-nitrosylation and 3-nitrotyrosination on proteins with potential modulation of function but limit the analyses to signalling involved in synaptic transmission and vesicular release. Here, crucial proteins which mediate synaptic transmission can undergo posttranslational modifications with either pre- or postsynaptic origin. During normal brain function, both pathways serve as important cellular signalling cascades that modulate a diverse array of physiological processes, including synaptic plasticity, transcriptional activity, and neuronal survival. In contrast, evidence suggests that aging and disease can induce nitrosative stress via excessive NO production. Consequently, uncontrolled S-nitrosylation/3-nitrotyrosination can occur and represent pathological features that contribute to the onset and progression of various neurodegenerative diseases, including Parkinson's, Alzheimer's, and Huntington's.

Multi-walled carbon nanotube inhibits CA1 glutamatergic synaptic transmission in rat's hippocampal slices

The purpose of the study was to investigate the neurotoxic effect of multi-walled carbon nanotubes (MWCNTs) on the properties of glutamatergic synaptic transmission in rat's hippocampal slices using whole-cell patch clamp technique. The amplitude and frequency of excitatory postsynaptic current (EPSC) were accessed on the hippocampal pyramidal neurons. The alterations of glutamatergic synaptic transmission in CA3-CA1 were examined by measuring both the amplitude of evoked excitatory postsynaptic current (eEPSC) and paired-pulse ratio (PPR). The data showed that the amplitude of either spontaneous excitatory postsynaptic current (sEPSC) or miniature excitatory postsynaptic current (mEPSC) was significantly inhibited by 1 μg/mL MWCNTs. However, it was found that there was a trend of different change on the frequency index. When 1 μg/mL MWCNTs was applied, there were a decreased frequency of mEPSC and an increased frequency of sEPSC, which might be due to the effect of action potential. Furthermore, the amplitudes of eEPSC at CA3-CA1 synapses were remarkably decreased. And the mean amplitude of AMPAR-mediated eEPSC was significantly reduced as well. Meanwhile, a majority of PPRs data were greater than one. There were no significant differences of PPRs between control and MWCNTs states, but an increased trend of paired-pulse facilitation was found. These results suggested that MWCNT markedly inhibited hippocampal CA1 glutamatergic synaptic transmission in vitro, which provided new insights into the MWCNT toxicology on CNS at cellular level.

The synergetic effect of edaravone and borneol in the rat model of ischemic stroke

Free radical production contributes to the early ischemic response and the neuroinflammatory response to injury initiates the second wave of cell death following ischemic stroke. Edaravone is a free radical scavenger, and borneol has shown anti-inflammatory effect. We investigated the synergistic effect of these two drugs in the rat model of transient cerebral ischemia. Edaravone scavenged OH, NO and ONOO─ concentration-dependently, and borneol inhibited ischemia/reperfusion-induced tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β) and cyclooxygenase-2 (COX-2) expressions. In the rat model of transient cerebral ischemia and reperfusion, the combination of edaravone and borneol significantly ameliorated ischemic damage with an optimal proportion of 4:1. Emax (% inhibition) of edaravone, borneol and two drugs in combination was 55.7%, 65.8% and 74.3% respectively. ED50 of edaravone and borneol was 7.17 and 0.36 mg/kg respectively. When two drugs in combination, ED50 was 0.484 mg/kg, in which edaravone was 0.387 mg/kg (ineffective dose) and borneol was 0.097 mg/kg (ineffective dose). Combination index (CI)<1 among effects observed in experiments, suggesting a significant synergistic effect. Reduced levels of pro-inflammatory mediators and free radicals were probably associated with the synergistic effect of edaravone and borneol. The combination exhibited a therapeutic time window of 6h in ischemia/reperfusion model, and significantly ameliorated damages in permanent ischemia model. Moreover, two drugs in combination promoted long-term effect, including improved elemental vital signs, sensorimotor functions and spatial cognition. Our results suggest that the combination of edaravone and borneol have a synergistic effect for treating ischemic stroke.

VEGF ameliorates cognitive impairment in in vivo and in vitro ischemia via improving neuronal viability and function

Vascular endothelial growth factor (VEGF) has recently been proved to be a potential therapeutic drug in ischemic disorders depending on the dose, route and time of administration, especially in focal cerebral ischemia. Whether VEGF could exert protection in a long-term total cerebral ischemic model is still uncertain, and the cellular mechanism has not been clarified so far. In order to answer the above issue, an experiment was performed in non-invasively giving exogenous VEGF to a total cerebral ischemic model rats and examining their spatial cognitive function by performing Morris water maze and long-term potential test. Moreover, we performed in vitro experiment to explore the cellular mechanism of VEGF protection effect. In an in vitro ischemia model oxygen-glucose deprivation (OGD), whole-cell patch-clamp recording was employed to examine neuronal function. Additionally, hematoxylin-eosin and propidium iodide staining were applied in vivo and in vitro in the neuropathological and viability study, separately. Our results showed that intranasal administration of VEGF could improve the cognitive function, synaptic plasticity and damaged hippocampal neurons in a global cerebral ischemia model. In addition, VEGF could retain the membrane potential, neuronal excitability and spontaneous excitatory postsynaptic currents in the early stage of ischemia, which further demonstrated that there was an acute effect of VEGF in OGD-induced pyramidal neurons. Simultaneously, it was also found that the death of CA1 pyramidal neuronal was significantly reduced by VEGF, but there was no similar effect in VEGF coexists with SU5416 group. These results indicated that VEGF could ameliorate cognitive impairment and synaptic plasticity via improving neuronal viability and function through acting on VEGFR-2.