Learning-induced synaptic potentiation in implanted neural precursor cell-derived neurons

RNA-Seq time-course analysis of neural precursor cell transcriptome in response to herpes simplex Virus-1 infection

The neurogenic niches within the central nervous system serve as essential reservoirs for neural precursor cells (NPCs), playing a crucial role in neurogenesis. However, these NPCs are particularly vulnerable to infection by the herpes simplex virus 1 (HSV-1). In the present study, we investigated the changes in the transcriptome of NPCs in response to HSV-1 infection using bulk RNA-Seq, compared to those of uninfected samples, at different time points post infection and in the presence or absence of antivirals. The results showed that NPCs upon HSV-1 infection undergo a significant dysregulation of genes playing a crucial role in aspects of neurogenesis, including genes affecting NPC proliferation, migration, and differentiation. Our analysis revealed that the CREB signaling, which plays a crucial role in the regulation of neurogenesis and memory consolidation, was the most consistantly downregulated pathway, even in the presence of antivirals. Additionally, cholesterol biosynthesis was significantly downregulated in HSV-1-infected NPCs. The findings from this study, for the first time, offer insights into the intricate molecular mechanisms that underlie the neurogenesis impairment associated with HSV-1 infection.

Panax notoginseng saponins stimulates the differentiation and neurite development of C17.2 neural stem cells against OGD/R injuries via mTOR signaling

Ischemic stroke remains a major disease worldwide, and most stroke patients often suffer from serious sequelae. Endogenous neurogenesis matters in the repair and regeneration of impaired neural cells after stroke. We have previously reported in vivo that PNS could strengthen the proliferation and differentiation of neural stem cells (NSCs), modulate synaptic plasticity and protect against ischemic brain injuries in cerebral ischemia rats, which could be attributed to mTOR signaling activation. Next, to obtain further insights into the function mechanism of PNS, we evaluated the direct influence of PNS on the survival, differentiation and synaptic development of C17.2 NSCs in vitro. The oxygen glucose deprivation/reperfusion (OGD/R) model was established to mimic ischemic brain injuries. We found that after OGD/R injuries, PNS improved the survival of C17.2 cells. Moreover, PNS enhanced the differentiation of C17.2 cells into neurons and astrocytes, and further promoted synaptic plasticity by significantly increasing the expressions of synapse-related proteins BDNF, SYP and PSD95. Meanwhile, PNS markedly activated the Akt/mTOR/p70S6K pathway. Notably, the mTOR inhibitor rapamycin pretreatment could reverse these desirable results. In conclusion, PNS possessed neural differentiation-inducing properties in mouse C17.2 NSCs after OGD/R injuries, and Akt/mTOR/p70S6K signaling pathway was proved to be involved in the differentiation and synaptic development of C17.2 cells induced by PNS treatment under the in vitro ischemic condition. Our findings offer new insights into the mechanisms that PNS regulate neural plasticity and repair triggered by NSCs, and highlight the potential of mTOR signaling as a therapeutic target for neural restoration after ischemic stroke.

The impact of acupuncture on neuroplasticity after ischemic stroke: a literature review and perspectives

Ischemic stroke is common in the elderly, and is one of the main causes of long-term disability worldwide. After ischemic stroke, spontaneous recovery and functional reconstruction take place. These processes are possible thanks to neuroplasticity, which involves neurogenesis, synaptogenesis, and angiogenesis. However, the repair of ischemic damage is not complete, and neurological deficits develop eventually. The WHO recommends acupuncture as an alternative and complementary method for the treatment of stroke. Moreover, clinical and experimental evidence has documented the potential of acupuncture to ameliorate ischemic stroke-induced neurological deficits, particularly sequelae such as dyskinesia, spasticity, cognitive impairment, and dysphagia. These effects are related to the ability of acupuncture to promote spontaneous neuroplasticity after ischemic stroke. Specifically, acupuncture can stimulate neurogenesis, activate axonal regeneration and sprouting, and improve the structure and function of synapses. These processes modify the neural network and function of the damaged brain area, producing the improvement of various skills and adaptability. Astrocytes and microglia may be involved in the regulation of neuroplasticity by acupuncture, such as by the production and release of a variety of neurotrophic factors, including brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Moreover, the evidence presented indicates that acupuncture promotes neuroplasticity by modulating the functional reconstruction of the whole brain after ischemia. Therefore, the promotion of neuroplasticity is expected to become a new target for acupuncture in the treatment of neurological deficits after ischemic stroke, and research into the mechanisms responsible for these actions will be of significant clinical value.

A functional hiPSC-cortical neuron differentiation and maturation model and its application to neurological disorders

The maturation and functional characteristics of human induced pluripotent stem cell (hiPSC)-cortical neurons has not been fully documented. This study developed a phenotypic model of hiPSC-derived cortical neurons, characterized their maturation process, and investigated its application for disease modeling with the integration of multi-electrode array (MEA) technology. Immunocytochemistry analysis indicated early-stage neurons (day 21) were simultaneously positive for both excitatory (vesicular glutamate transporter 1 [VGlut1]) and inhibitory (GABA) markers, while late-stage cultures (day 40) expressed solely VGlut1, indicating a purely excitatory phenotype without containing glial cells. This maturation process was further validated utilizing patch clamp and MEA analysis. Particularly, induced long-term potentiation (LTP) successfully persisted for 1 h in day 40 cultures, but only achieved LTP in the presence of the GABA_A receptor antagonist picrotoxin in day 21 cultures. This system was also applied to epilepsy modeling utilizing bicuculline and its correction utilizing the anti-epileptic drug valproic acid.

•

Characterization of human cortical neuronal differentiation to a mature phenotype

•

Microelectrode evaluation of development from a mixed to pure excitatory population

•

Utilization of defined culture stage to create an epilepsy model

•

Manipulation of immaturity with inhibitors for maintaining long-term potentiation

Cognitive Deficits after Cerebral Ischemia and Underlying Dysfunctional Plasticity: Potential Targets for Recovery of Cognition

Cerebral ischemia affects millions of people worldwide and survivors suffer from long-term functional and cognitive deficits. While stroke and cardiac arrest are typically considered when discussing ischemic brain injuries, there is much evidence that smaller ischemic insults underlie neurodegenerative diseases, including Alzheimer's disease. The "regenerative" capacity of the brain relies on several aspects of plasticity that are crucial for normal functioning; less affected brain areas may take over function previously performed by irreversibly damaged tissue. To harness the endogenous plasticity mechanisms of the brain to provide recovery of cognitive function, we must first understand how these mechanisms are altered after damage, such as cerebral ischemia. In this review, we discuss the long-term cognitive changes that result after cerebral ischemia and how ischemia alters several plasticity processes. We conclude with a discussion of how current and prospective therapies may restore brain plasticity and allow for recovery of cognitive function, which may be applicable to several disorders that have a disruption of cognitive processing, including traumatic brain injury and Alzheimer's disease.

Effect of aucubin on neural precursor cell survival during neuronal differentiation

PURPOSE OF THE STUDY

Aucubin (ACB) is an iridoid glycoside with various biological activities. Previously, it is reported that ACB reduces cell survival and proliferation in many human tumors, whereas it facilitates cell survival and neuroprotection in damaged neuronal cells and disease models. However, its effects on cell survival in the non-proliferating or differentiated neurons are not known.

MATERIALS AND METHODS

We examined whether ACB facilitated cell survival in differentiating neural precursor cells, HiB5, compared with the proliferating HiB5 cells at various concentrations.

RESULTS

The cell viabilities were evaluated by measuring MTT values, cell numbers, amounts of neurotransmittersD1 and protein amounts of neuronal markers. Here, we showed that ACB promotes cell survival in differentiated neurons (10-200 μg/mL), but reduces it in proliferating NPCs (200-400 μg/mL). Protein amounts of neurofilament proteins, NF-H, NF-M, PSD-95 in post-synaptic density, GAP-43 in growing neurites and NeuN in differentiated neurons were upregulated by addition of ACB, indicating that cell survival increased in differentiated neurons, shown by immunoblot analysis. Especially, when PDGF was added into N2 media to facilitate neuronal differentiation of HiB5 cells, the viability of differentiated HiB5 cells was significantly elevated following the increase of ACB concentration. Furthermore, ACB promoted cell survival of specific neuron types, such as GABAergic neurons and glutamatergic neurons. When differentiated neurons were immunostained with markers for specific neurons, neuronal subtypes producing GABA and GAD 65/67 were immunostained more than subtypes producing glutamate and vGluT1.

CONCLUSION

These results indicate that ACB improves neuronal cell survival in differentiated cells, suggesting it may be a therapeutic compound for neurodegenerative disorders.

Therapeutic Potentials of Synapses after Traumatic Brain Injury: A Comprehensive Review

Massive studies have focused on the understanding of the pathobiology of cellular and molecular changes and injury mechanisms after traumatic brain injury (TBI), but very few studies have specially discussed the role of synapses in the context of TBI. This paper specifically highlights the role and therapeutic potentials of synapses after TBI. First, we review and conclude how synapses interact with constant structural, metabolic, neuroendocrine, and inflammatory mechanisms after TBI. Second, we briefly describe several key synaptic proteins involved in neuroplasticity, which may be novel neuronal targets for specific intervention. Third, we address therapeutic interventions in association with synapses after TBI. Finally, we concisely discuss the study gaps in the synapses after TBI, in hopes that this would provide more insights for future studies. Synapses play an important role in TBI; while the understandings on the synaptic participation in the treatments and prognosis of TBI are lacking, more studies in this area are warranted.

Electroacupuncture Regulates Hippocampal Synaptic Plasticity via miR-134-Mediated LIMK1 Function in Rats with Ischemic Stroke

MircoRNAs (miRs) have been implicated in learning and memory, by regulating LIM domain kinase (LIMK1) to induce synaptic-dendritic plasticity. The study aimed to investigate whether miRNAs/LIMK1 signaling was involved in electroacupuncture- (EA-) mediated synaptic-dendritic plasticity in a rat model of middle cerebral artery occlusion induced cognitive deficit (MICD). Compared to untreatment or non-acupoint-EA treatment, EA at DU20 and DU24 acupoints could shorten escape latency and increase the frequency of crossing platform in Morris water maze test. T2-weighted imaging showed that the MICD rat brain lesions were located in cortex, hippocampus, corpus striatum, and thalamus regions and injured volumes were reduced after EA. Furthermore, we found that the density of dendritic spine and the number of synapses in the hippocampal CA1 pyramidal cells were obviously reduced at Day 14 after MICD. However, synaptic-dendritic loss could be rescued after EA. Moreover, the synaptic-dendritic plasticity was associated with increases of the total LIMK1 and phospho-LIMK1 levels in hippocampal CA1 region, wherein EA decreased the expression of miR-134, negatively regulating LIMK1 to enhance synaptic-dendritic plasticity. Therefore, miR-134-mediated LIMK1 was involved in EA-induced hippocampal synaptic plasticity, which served as a contributor to improving learning and memory during the recovery stage of ischemic stroke.