Agmatine enhances neurogenesis by increasing ERK1/2 expression, and suppresses astrogenesis by decreasing BMP 2,4 and SMAD 1,5,8 expression in subventricular zone neural stem cells

Agmatine modulation of gut-brain axis alleviates dysbiosis-induced depression-like behavior in rats

Depression is a global health concern affecting nearly 280 million individuals. It not only imposes a significant burden on economies and healthcare systems but also manifests complex physiological connections and consequences. Agmatine, a putative neuromodulator derived primarily from beneficial gut microbes specially Lactobacillus, has emerged as a potential therapeutic agent for mental health. The microbiota-gut-brain axis is involved in the development of depression through the peripheral nervous system, endocrine system, and immune system and may be a key factor in the effect of agmatine. Therefore, this study aimed to investigate the potential mechanism of agmatine in antibiotic-induced dysbiosis and depression-like behavior in rats, focusing on its modulation of the gut-brain axis. Depression-like behavior associated with dysbiosis was induced through a seven-day regimen of the broad-spectrum antibiotic, comprising ampicillin and metronidazole and validated through microbial, biochemical, and behavioral alterations. On day 8, antibiotic-treated rats exhibited loose fecal consistency, altered fecal microbiota, and depression-like behavior in forced swim test. Pro-inflammatory cytokines were elevated, while agmatine and monoamine levels decreased in the hippocampus and prefrontal cortex. Antibiotic administration disrupted tight junction proteins in the ileum, affecting gut architecture. Oral administration of agmatine alone or combined with probiotics significantly reversed antibiotic-induced dysbiosis, restoring gut microbiota and mitigating depression-like behaviors. This intervention also restored neuro-inflammatory markers, increased agmatine and monoamine levels, and preserved gut integrity. The study highlights the regulatory role of endogenous agmatine in the gut-brain axis in broad-spectrum antibiotic induced dysbiosis and associated depression-like behavior.

The Neuroprotective Effects of Agmatine on Parkinson's Disease: Focus on Oxidative Stress, Inflammation and Molecular Mechanisms

Agmatine (AGM), a naturally occurring polyamine derived from L-arginine, has shown significant potential for neuroprotection in Parkinson's Disease (PD) due to its multifaceted biological activities, including antioxidant, anti-inflammatory, and anti-apoptotic effects. This review explores the therapeutic potential of AGM in treating PD, focusing on its neuroprotective mechanisms and evidence from preclinical studies. AGM has been demonstrated to mitigate the neurotoxic effects of rotenone (ROT) by improving motor function, reducing oxidative stress markers, and decreasing levels of pro-inflammatory cytokines in animal models. Additionally, AGM protects against the loss of TH + neurons, crucial for dopamine synthesis. The neuroprotective properties of AGM are attributed to its ability to modulate several key pathways implicated in PD pathogenesis, such as inhibition of NMDA receptors, activation of Nrf2, and suppression of the HMGB1/ RAGE/ TLR4/ MyD88/ NF-κB signaling cascade. Furthermore, the potential of agmatine to promote neurorestoration is highlighted by its role in enhancing neuroplasticity elements such as CREB, BDNF, and ERK1/2. This review highlights agmatine's promising therapeutic potential in PD management, suggesting that it could offer both symptomatic relief and neuroprotective benefits, thereby modifying the disease course and improving the quality of life for patients. Further research is warranted to translate these preclinical findings into clinical applications.

Bone morphogenetic protein 4 derived from the cerebrospinal fluid in patients with postherpetic neuralgia induces allodynia via the crosstalk between microglia and astrocyte

INTRODUCTION

During postherpetic neuralgia (PHN), the cerebral spinal fluid (CSF) possesses the capability to trigger glial activation and inflammation, yet the specific changes in its composition remain unclear. Recent findings from our research indicate elevations of central bone morphogenetic protein 4 (BMP4) during neuropathic pain (NP), serving as an independent modulator of glial cells. Herein, the aim of the present study is to test the CSF-BMP4 expressions and its role in the glial modulation in the process of PHN.

METHODS

CSF samples were collected from both PHN patients and non-painful individuals (Control) to assess BMP4 and its antagonist Noggin levels. Besides, intrathecal administration of both CSF types was conducted in normal rats to evaluate the impact on pain behavior, glial activity, and inflammation.; Additionally, both Noggin and STAT3 antagonist-Stattic were employed to treat the PHN-CSF or exogenous BMP4 challenged cultured astrocytes to explore downstream signals. Finally, microglial depletion was performed prior to the PHN-CSF intervention so as to elucidate the microglia-astrocyte crosstalk.

RESULTS

BMP4 levels were significantly higher in PHN-CSF compared to Control-CSF (P < 0.001), with a positive correlation with pain duration (P < 0.05, r = 0.502). Comparing with the Control-CSF producing moderate paw withdrawal threshold (PWT) decline and microglial activation, PHN-CSF further exacerbated allodynia and triggered both microglial and astrocytic activation (P < 0.05). Moreover, PHN-CSF rather than Control-CSF evoked microglial proliferation and pro-inflammatory transformation, reinforced iron storage, and activated astrocytes possibly through both SMAD159 and STAT3 signaling, which were all mitigated by the Noggin application (P < 0.05). Next, both Noggin and Stattic effectively attenuated BMP4-induced GFAP and IL-6 upregulation, as well as SMAD159 and STAT3 phosphorylation in the cultured astrocytes (P < 0.05). Finally, microglial depletion diminished PHN-CSF induced astrogliosis, inflammation and endogenous BMP4 expression (P < 0.05).

CONCLUSION

Our study highlights the role of CSF-BMP4 elevation in glial activation and allodynia during PHN, suggesting a potential therapeutic avenue for future exploration.

Pharmacological profile of agmatine: An in-depth overview

Agmatine, a naturally occurring polyamine derived from arginine via arginine decarboxylase, has been shown to play multifaceted roles in the mammalian body, impacting a wide range of physiological and pathological processes. This comprehensive review delineates the significant insights into agmatine's pharmacological profile, emphasizing its structure and metabolism, neurotransmission and regulation, and pharmacokinetics and function. Agmatine's biosynthesis is highly conserved across species, highlighting its fundamental role in cellular functions. In the brain, comparable to established neurotransmitters, agmatine acts as a neuromodulator, influencing the regulation, metabolism, and reabsorption of neurotransmitters that are key to mood disorders, learning, cognition, and the management of anxiety and depression. Beyond its neuromodulatory functions, agmatine exhibits protective effects across various cellular and systemic contexts, including neuroprotection, nephroprotection, cardioprotection, and cytoprotection, suggesting a broad therapeutic potential. The review explores agmatine's interaction with multiple receptor systems, including NMDA, α2-adrenoceptors, and imidazoline receptors, elucidating its role in enhancing cell viability, neuronal protection, and synaptic plasticity. Such interactions underpin agmatine's potential in treating neurological diseases and mood disorders, among other conditions. Furthermore, agmatine's pharmacokinetics, including its absorption, distribution, metabolism, and excretion, are discussed, underlining the complexity of its action and the potential for therapeutic application. The safety and efficacy of agmatine supplementation, demonstrated through various animal and human studies, affirm its potential as a beneficial therapeutic agent. Conclusively, the diverse physiological and therapeutic effects of agmatine, spanning neurotransmission, protection against cellular damage, and modulation of various receptor pathways, position it as a promising candidate for further research and clinical application. This review underscores the imperative for continued exploration into agmatine's mechanisms of action and its potential in pharmacology and medicine, promising advances in the treatment of numerous conditions.

Agmatine as a novel intervention for Alzheimer's disease: Pathological insights and cognitive benefits

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by progressive cognitive decline and a significant societal burden. Despite extensive research and efforts of the multidisciplinary scientific community, to date, there is no cure for this debilitating disease. Moreover, the existing pharmacotherapy for AD only provides symptomatic support and does not modify the course of the illness or halt the disease progression. This is a significant limitation as the underlying pathology of the disease continues to progress leading to the deterioration of cognitive functions over time. In this milieu, there is a growing need for the development of new and more efficacious treatments for AD. Agmatine, a naturally occurring molecule derived from L-arginine, has emerged as a potential therapeutic agent for AD. Besides this, agmatine has been shown to modulate amyloid beta (Aβ) production, aggregation, and clearance, key processes implicated in AD pathogenesis. It also exerts neuroprotective effects, modulates neurotransmitter systems, enhances synaptic plasticity, and stimulates neurogenesis. Furthermore, preclinical and clinical studies have provided evidence supporting the cognition-enhancing effects of agmatine in AD. Therefore, this review article explores the promising role of agmatine in AD pathology and cognitive function. However, several limitations and challenges exist, including the need for large-scale clinical trials, optimal dosing, and treatment duration. Future research should focus on mechanistic investigations, biomarker studies, and personalized medicine approaches to fully understand and optimize the therapeutic potential of agmatine. Augmenting the use of agmatine may offer a novel approach to address the unmet medical need in AD and provide cognitive enhancement and disease modification for individuals affected by this disease.

Neuroprotection by agmatine: Possible involvement of the gut microbiome?

Agmatine, an endogenous polyamine derived from L-arginine, elicits tremendous multimodal neuromodulant properties. Alterations in agmatinergic signalling are closely linked to the pathogeneses of several brain disorders. Importantly, exogenous agmatine has been shown to act as a potent neuroprotectant in varied pathologies, including brain ageing and associated comorbidities. The antioxidant, anxiolytic, analgesic, antidepressant and memory-enhancing activities of agmatine may derive from its ability to regulate several cellular pathways; including cell metabolism, survival and differentiation, nitric oxide signalling, protein translation, oxidative homeostasis and neurotransmitter signalling. This review briefly discusses mammalian metabolism of agmatine and then proceeds to summarize our current understanding of neuromodulation and neuroprotection mediated by agmatine. Further, the emerging exciting bidirectional links between agmatine and the resident gut microbiome and their implications for brain pathophysiology and ageing are also discussed.

Neural Stem Cells Overexpressing Arginine Decarboxylase Improve Functional Recovery from Spinal Cord Injury in a Mouse Model

Current therapeutic strategies for spinal cord injury (SCI) cannot fully facilitate neural regeneration or improve function. Arginine decarboxylase (ADC) synthesizes agmatine, an endogenous primary amine with neuroprotective effects. Transfection of human ADC (hADC) gene exerts protective effects after injury in murine brain-derived neural precursor cells (mNPCs). Following from these findings, we investigated the effects of hADC-mNPC transplantation in SCI model mice. Mice with experimentally damaged spinal cords were divided into three groups, separately transplanted with fluorescently labeled (1) control mNPCs, (2) retroviral vector (pLXSN)-infected mNPCs (pLXSN-mNPCs), and (3) hADC-mNPCs. Behavioral comparisons between groups were conducted weekly up to 6 weeks after SCI, and urine volume was measured up to 2 weeks after SCI. A subset of animals was euthanized each week after cell transplantation for molecular and histological analyses. The transplantation groups experienced significantly improved behavioral function, with the best recovery occurring in hADC-mNPC mice. Transplanting hADC-mNPCs improved neurological outcomes, induced oligodendrocyte differentiation and remyelination, increased neural lineage differentiation, and decreased glial scar formation. Moreover, locomotor and bladder function were both rehabilitated. These beneficial effects are likely related to differential BMP-2/4/7 expression in neuronal cells, providing an empirical basis for gene therapy as a curative SCI treatment option.

Astrocyte and Oligodendrocyte Responses From the Subventricular Zone After Injury

Under normal conditions, neural stem cells (NSCs or B cells) in the adult subventricular zone (SVZ) give rise to amplifying neural progenitor cells (NPCs or C cells), which can produce neuroblasts (or A cells) that migrate to the olfactory bulb and differentiate into new neurons. However, following brain injury, these cells migrate toward the injury site where they differentiate into astrocytes and oligodendrocytes. In this review, we will focus on recent findings that chronicle how astrocytes and oligodendrocytes derived from SVZ-NSCs respond to different types of injury. We will also discuss molecular regulators of SVZ-NSC proliferation and their differentiation into astrocytes and oligodendrocytes. Overall, the goal of this review is to highlight how SVZ-NSCs respond to injury and to summarize the regulatory mechanisms that oversee their glial response. These molecular and cellular processes will provide critical insights needed to develop strategies to promote brain repair following injury using SVZ-NSCs.

Role of agmatine in the application of neural progenitor cell in central nervous system diseases: therapeutic potentials and effects

Agmatine, the primary decarboxylation product of L-arginine, generated from arginine decarboxylase. Since the discovery of agmatine in the mammalian brain in the 1990s, an increasing number of agmatine-mediated effects have been discovered, demonstrating the benefits of agmatine on ischemic strokes, traumatic brain injury and numerous psychological disorders such as depression, anxiety, and stress. Agmatine also has cellular protective effects and contributes to cell proliferation and differentiation in the central nervous system (CNS). Neural progenitor cells are an important component in the recovery and repair of many neurological disorders due to their ability to differentiate into functional adult neurons. Recent data has revealed that agmatine can regulate and increase proliferation and the fate of progenitor cells in the adult hippocampus. This review aims to summarise and discuss the role of agmatine in the CNS; specifically, the effects and relationship between agmatine and neural progenitor cells and how these ideas can be applied to potential therapeutic application.

The Smad Dependent TGF-β and BMP Signaling Pathway in Bone Remodeling and Therapies

Bone remodeling is a continuous process that maintains the homeostasis of the skeletal system, and it depends on the homeostasis between bone-forming osteoblasts and bone-absorbing osteoclasts. A large number of studies have confirmed that the Smad signaling pathway is essential for the regulation of osteoblastic and osteoclastic differentiation during skeletal development, bone formation and bone homeostasis, suggesting a close relationship between Smad signaling and bone remodeling. It is known that Smads proteins are pivotal intracellular effectors for the members of the transforming growth factor-β (TGF-β) and bone morphogenetic proteins (BMP), acting as transcription factors. Smad mediates the signal transduction in TGF-β and BMP signaling pathway that affects both osteoblast and osteoclast functions, and therefore plays a critical role in the regulation of bone remodeling. Increasing studies have demonstrated that a number of Smad signaling regulators have potential functions in bone remodeling. Therefore, targeting Smad dependent TGF-β and BMP signaling pathway might be a novel and promising therapeutic strategy against osteoporosis. This article aims to review recent advances in this field, summarizing the influence of Smad on osteoblast and osteoclast function, together with Smad signaling regulators in bone remodeling. This will facilitate the understanding of Smad signaling pathway in bone biology and shed new light on the modulation and potential treatment for osteoporosis.

Effects of primary microglia and astrocytes on neural stem cells in in vitro and in vivo models of ischemic stroke

Transplantation of neural stem cells (NSCs) can protect neurons in animal stroke models; however, their low rates of survival and neuronal differentiation limit their clinical application. Glial niches, an important location of neural stem cells, regulate survival, proliferation and differentiation of neural stem cells. However, the effects of activated glial cells on neural stem cells remain unclear. In the present study, we explored the effects of activated astrocytes and microglia on neural stem cells in vitro stroke models. We also investigated the effects of combined transplantation of neural stem cells and glial cells after stroke in rats. In a Transwell co-culture system, primary cultured astrocytes, microglia or mixed glial cells were exposed to glutamate or H₂O₂ and then seeded in the upper inserts, while primary neural stem cells were seeded in the lower uncoated wells and cultured for 7 days. Our results showed that microglia were conducive to neurosphere formation and had no effects on apoptosis within neurospheres, while astrocytes and mixed glial cells were conducive to neurosphere differentiation and reduced apoptosis within neurospheres, regardless of their pretreatment. In contrast, microglia and astrocytes induced neuronal differentiation of neural stem cells in differentiation medium, regardless of their pretreatment, with an exception of astrocytes pretreated with H₂O₂. Rat models of ischemic stroke were established by occlusion of the middle cerebral artery. Three days later, 5 × 10⁵ neural stem cells with microglia or astrocytes were injected into the right lateral ventricle. Neural stem cell/astrocyte-treated rats displayed better improvement of neurological deficits than neural stem cell only-treated rats at 4 days after cell transplantation. Moreover, neural stem cell/microglia-, and neural stem cell/astrocyte-treated rats showed a significant decrease in ischemic volume compared with neural stem cell-treated rats. These findings indicate that microglia and astrocytes exert different effects on neural stem cells, and that co-transplantation of neural stem cells and astrocytes is more conducive to the recovery of neurological impairment in rats with ischemic stroke. The study was approved by the Animal Ethics Committee of Tongji University School of Medicine, China (approval No. 2010-TJAA08220401) in 2010.

Arginase Inhibition Supports Survival and Differentiation of Neuronal Precursors in Adult Alzheimer's Disease Mice

Adult neurogenesis is a complex physiological process, which plays a central role in maintaining cognitive functions, and consists of progenitor cell proliferation, newborn cell migration, and cell maturation. Adult neurogenesis is susceptible to alterations under various physiological and pathological conditions. A substantial decay of neurogenesis has been documented in Alzheimer’s disease (AD) patients and animal AD models; however, several treatment strategies can halt any further decline and even induce neurogenesis. Our previous results indicated a potential effect of arginase inhibition, with norvaline, on various aspects of neurogenesis in triple-transgenic mice. To better evaluate this effect, we chronically administered an arginase inhibitor, norvaline, to triple-transgenic and wild-type mice, and applied an advanced immunohistochemistry approach with several biomarkers and bright-field microscopy. Remarkably, we evidenced a significant reduction in the density of neuronal progenitors, which demonstrate a different phenotype in the hippocampi of triple-transgenic mice as compared to wild-type animals. However, norvaline showed no significant effect upon the progenitor cell number and constitution. We demonstrated that norvaline treatment leads to an escalation of the polysialylated neuronal cell adhesion molecule immunopositivity, which suggests an improvement in the newborn neuron survival rate. Additionally, we identified a significant increase in the hippocampal microtubule-associated protein 2 stain intensity. We also explore the molecular mechanisms underlying the effects of norvaline on adult mice neurogenesis and provide insights into their machinery.

Restorative Mechanism of Neural Progenitor Cells Overexpressing Arginine Decarboxylase Genes Following Ischemic Injury

Cell replacement therapy using neural progenitor cells (NPCs) following ischemic stroke is a promising potential therapeutic strategy, but lacks efficacy for human central nervous system (CNS) therapeutics. In a previous in vitro study, we reported that the overexpression of human arginine decarboxylase (ADC) genes by a retroviral plasmid vector promoted the neuronal differentiation of mouse NPCs. In the present study, we focused on the cellular mechanism underlying cell proliferation and differentiation following ischemic injury, and the therapeutic feasibility of NPCs overexpressing ADC genes (ADC-NPCs) following ischemic stroke. To mimic cerebral ischemia in vitro , we subjected the NPCs to oxygen-glucose deprivation (OGD). The overexpressing ADC-NPCs were differentiated by neural lineage, which was related to excessive intracellular calcium-mediated cell cycle arrest and phosphorylation in the ERK1/2, CREB, and STAT1 signaling cascade following ischemic injury. Moreover, the ADC-NPCs were able to resist mitochondrial membrane potential collapse in the increasingly excessive intracellular calcium environment. Subsequently, transplanted ADC-NPCs suppressed infarct volume, and promoted neural differentiation, synapse formation, and motor behavior performance in an in vivo tMCAO rat model. The results suggest that ADC-NPCs are potentially useful for cell replacement therapy following ischemic stroke.

Agmatine modulates calcium handling in cardiomyocytes of hibernating ground squirrels through calcium-sensing receptor signaling

True hibernators are remarkable group of mammals whose hearts are resistant to such stressors as deep hypothermia, ischemia, arrhythmia. Capability of cardiac cells from hibernating species to effectively rule Ca²⁺ homeostasis during torpor is poorly studied. Better understanding of these mechanisms could allow to introduce new strategies for improvement the cardiac performance and may be useful for cardiovascular medicine. Here for the first time we have shown that the regulation of Ca²⁺ handling and thereby cardiomyocyte contractility by endogenous neurotransmitter agmatine occurs through the modulation of calcium-sensing receptor (CaSR). In isolated cardiocytes of hibernating ground squirrels generating stationary Ca²⁺ transients in the absence of actual myocellular excitation, low doses of this polyamine (up to 500 μM) induce the G_βγ-dependent activation of PI₃-kinase with subsequent stimulation of Akt-kinase and nitric oxide (NO) production by endothelial NO-synthase (eNOS). NO production abolishes Ca²⁺ oscillations in virtue of the enhancement of Ca²⁺ reuptake by sarco(endo)plasmic Ca²⁺ ATPase (SERCA). Simultaneously, the activation of phospholipase A₂ (PLA₂) and arachidonic-acid dependent Ca²⁺ entry occur providing replenishment of Ca²⁺ store. High concentrations of agmatine (> 2 mM) induce other CaSR-mediated pathways involving phospholipase C (PLC) pathway, the formation of inositoltriphosphate (IP₃) and diacylglicerol (DAG) followed by induction of their targets: IP₃ receptors and protein kinase C isoforms (PKC), respectively. Furthermore, it is also responsible for the stimulation of PLA₂ and elevation of intracellular calcium caused by arachidonic acid-regulated Ca²⁺-permeable (ARC) channels. Additionally, there is a potent store-operated Ca²⁺ entry (SOC) in cardiomyocyte. Negative (NPS 2143) and positive (R 568) allosteric modulators of CaSR recapitulate effects of low and high agmatine doses on Ca²⁺ handling and NO synthesis. These facts and the alteration of agmatine influence in response to an increase of extracellular Ca²⁺, which is the direct agonist of CaSR, may confirm the participation of CaSR in regulation of Ca²⁺ handling and excitability of cardiomyocytes by agmatine.

MiRNA Influences in Neuroblast Modulation: An Introspective Analysis

Neuroblastoma (NB) is the most common occurring solid paediatric cancer in children under the age of five years. Whether of familial or sporadic origin, chromosome abnormalities contribute to the development of NB and cause dysregulation of microRNAs (miRNAs). MiRNAs are small non-coding, single stranded RNAs that target messenger RNAs at the post-transcriptional levels by repressing translation within all facets of human physiology. Such gene 'silencing' activities by miRNAs allows the development of regulatory feedback loops affecting multiple functions within the cell, including the possible differentiation of neural stem cell (NSC) lineage selection. Neurogenesis includes stages of self-renewal and fate specification of NSCs, migration and maturation of young neurones, and functional integration of new neurones into the neural circuitry, all of which are regulated by miRNAs. The role of miRNAs and their interaction in cellular processes are recognised aspects of cancer genetics, and miRNAs are currently employed as biomarkers for prognosis and tumour characterisation in multiple cancer models. Consequently, thorough understanding of the mechanisms of how these miRNAs interplay at the transcriptomic level will definitely lead to the development of novel, bespoke and efficient therapeutic measures, with this review focusing on the influences of miRNAs on neuroblast modulations leading to neuroblastoma.

Agmatine inhibits chronic morphine exposure-induced impairment of hippocampal neural progenitor proliferation in adult rats

Our previous studies have shown that agmatine inhibited opioid dependence, yet the neural mechanism remains unclear. Growing evidence showed that opioids decrease neurogenesis in the adult hippocampal subgranular zone by inhibiting neural progenitor proliferation. However, whether agmatine affects chronic opioid exposure-induced impairment to hippocampal neural progenitor cell proliferation remains unknown. In the present study, we investigated the role of agmatine in hippocampal neural progenitors in morphine dependence rats. We found that chronic administration of morphine for 12 days induced morphine dependence in rats. This treatment not only decreased the proliferation of hippocampal neural progenitors in the granule cell layer, but also decreased the levels of hippocampal cAMP, pCREB and BDNF. However, these alterations can be restored to normal levels by co-treatment of agmatine (10mg/kg, s.c.). In vitro treatment with agmatine (10µM) for two days significantly increased proliferation of the cultured hippocampal neural progenitors. Concurrent treatment of agmatine (10µM) with morphine (10 or 50µM) reversed the supression of morphine-induced neural progenitor proliferation. In conclusion, we found that agmatine abolished chronic morphine-induced decrease in proliferation of hippocampal progenitors in vivo and in vitro, which may be due to the increase in cAMP-CREB-BDNF signaling. The enhancement of agmatine to proliferation of hippocampal progenitors may be one of the important mechanisms involved in the inhibition of morphine dependence by agmatine.

Lsh/HELLS regulates self-renewal/proliferation of neural stem/progenitor cells

Epigenetic mechanisms are known to exert control over gene expression and determine cell fate. Genetic mutations in epigenetic regulators are responsible for several neurologic disorders. Mutations of the chromatin remodeling protein Lsh/HELLS can cause the human Immunodeficiency, Centromere instability and Facial anomalies (ICF) syndrome, which is associated with neurologic deficiencies. We report here a critical role for Lsh in murine neural development. Lsh depleted neural stem/progenitor cells (NSPCs) display reduced growth, increases in apoptosis and impaired ability of self-renewal. RNA-seq analysis demonstrates differential gene expression in Lsh-/- NSPCs and suggests multiple aberrant pathways. Concentrating on specific genomic targets, we show that ablation of Lsh alters epigenetic states at specific enhancer regions of the key cell cycle regulator Cdkn1a and the stem cell regulator Bmp4 in NSPCs and alters their expression. These results suggest that Lsh exerts epigenetic regulation at key regulators of neural stem cell fate ensuring adequate NSPCs self-renewal and maintenance during development.

Suppression of MicroRNA let-7a Expression by Agmatine Regulates Neural Stem Cell Differentiation

PURPOSE

Neural stem cells (NSCs) effectively reverse some severe central nervous system (CNS) disorders, due to their ability to differentiate into neurons. Agmatine, a biogenic amine, has cellular protective effects and contributes to cellular proliferation and differentiation in the CNS. Recent studies have elucidated the function of microRNA let-7a (let-7a) as a regulator of cell differentiation with roles in regulating genes associated with CNS neurogenesis.

MATERIALS AND METHODS

This study aimed to investigate whether agmatine modulates the expression of crucial regulators of NSC differentiation including DCX, TLX, c-Myc, and ERK by controlling let-7a expression.

RESULTS

Our data suggest that high levels of let-7a promoted the expression of TLX and c-Myc, as well as repressed DCX and ERK expression. In addition, agmatine attenuated expression of TLX and increased expression of ERK by negatively regulating let-7a.

CONCLUSION

Our study therefore enhances the present understanding of the therapeutic potential of NSCs in CNS disorders.

Transfection of arginine decarboxylase gene increases the neuronal differentiation of neural progenitor cells

Growing evidence suggests that the clinical use of neural progenitor cells (NPCs) is hampered by heterogeneity, poor neuronal yield and low survival rate. Recently, we reported that retrovirus-delivered human arginine decarboxylase (hADC) genes improve cell survival against oxidative insult in murine NPCs in vitro. This study investigates whether the induced expression of hADC gene in mNPCs induces any significant change in the cell fate commitment. The evaluation of induced hADC gene function was assessed by knockdown of hADC gene using specific siRNA. The hADC gene delivery triggered higher expression of N-CAM, cell adhesion molecule and MAP-2, neuronal marker. However, the hADC gene knockdown showed downregulation of N-CAM and MAP-2 expression suggesting that hADC gene delivery favors cell fate commitment of mNPCs towards neuronal lineage. Neurite outgrowth was significantly longer in the hADC infected cells. The neurotrophic signal, BDNF aided in the neuronal commitment, differentiation, and maturation of hADC-mNPCs through PI3K and ERK1/2 activation. The induction of neuron-like differentiation is believed to be regulated by the expression of GSK-3β and Wnt/β-catenin signaling pathways. Our findings suggest that hADC gene delivery favors cell fate commitment of mNPCs towards neuronal lineage, bring new advances in the field of neurogenesis and cell therapy.

Neuroprotective Effects of Bone Marrow Stromal Cell Transplantation in Combination With Treadmill Exercise Following Traumatic Brain Injury

Purpose:

Traumatic brain injury (TBI) causes cognitive impairments, motor deficits, and neuropsychiatric/behavioral deficits problems. Transplantation of bone marrow stromal cells (BMSCs) facilitates functional recovery from brain insults. Treadmill exercise increases neurogenesis and inhibits apoptosis. In this study, we investigated the effects of BMSC transplantation in combination with treadmill exercise on memory function, by evaluating its effect on neurogenesis and apoptosis in the hippocampus following TBI.

Methods:

TBI was induced using an electromagnetic-controlled cortical impact device. BMSCs were transplanted into both sides of traumatic scar region 1 week after TBI induction. One week after transplantation of BMSCs, the rats in the exercise groups were trained to run on a treadmill for 30 minutes once daily for 28 days. Step-down avoidance task and radial 8-arm maze test were conducted. Levels of 5-bromo-2ʹ-deoxyuridine and caspase-3 were evaluated using immunohistochemistry. Western blot was used to evaluate the expression of brain-derived neurotrophic factor (BDNF), tyrosine kinase B (TrkB), total-extracellular signal-regulated kinase 1 and 2 (t-ERK1/2), phosphorylated-ERK1/2 (p-ERK1/2), Bcl-2, and Bax.

Results:

TBI deteriorated memory function, suppressed neurogenesis, and accelerated apoptosis in the hippocampus. Treadmill exercise and BMSC transplantation independently improved memory function by increasing neurogenesis with suppression of apoptosis through the BDNF-ERK pathway in the TBI-induced rats. Combination of BMSC transplantation with treadmill exercise showed additional enhancement of neurogenesis and suppression of apoptosis in the hippocampus.

Conclusions:

The present study shows that treadmill exercise may aid the therapeutic effect of BMSC transplantation on TBI in rats.

The Effect of Agmatine on Expression of IL-1β and TLX Which Promotes Neuronal Differentiation in Lipopolysaccharide-Treated Neural Progenitors

Differentiation of neural progenitor cells (NPCs) is important for protecting neural cells and brain tissue during inflammation. Interleukin-1 beta (IL-1β) is the most common pro- inflammatory cytokine in brain inflammation, and increased IL-1β levels can decrease the proliferation of NPCs. We aimed to investigate whether agmatine (Agm), a primary polyamine that protects neural cells, could trigger differentiation of NPCs by activating IL-1β in vitro. The cortex of ICR mouse embryos (E14) was dissociated to culture NPCs. NPCs were stimulated by lipopolysaccharide (LPS). After 6 days, protein expression of stem cell markers and differentiation signal factors was confirmed by using western blot analysis. Also, immunocytochemistry was used to confirm the cell fate. Agm treatment activated NPC differentiation significantly more than in the control group, which was evident by the increased expression of a neuronal marker, MAP2, in the LPS-induced, Agm-treated group. Differentiation of LPS-induced, Agm-treated NPCs was regulated by the MAPK pathway and is thought to be related to IL-1β activation and decreased expression of TLX, a transcription factor that regulates NPC differentiation. Our results reveal that Agm can promote NPC differentiation to neural stem cells by modulating IL-1β expression under inflammatory condition, and they suggest that Agm may be a novel therapeutic strategy for neuroinflammatory diseases.

The role of the ERK1/2 signalling pathway in the pathogenesis of female stress urinary incontinence

Objective:

To investigate the role of extracellular-regulated protein kinase (ERK)1/2 and phosphorylated (p)-ERK1/2 in the pathogenesis of female stress urinary incontinence (SUI).

Methods:

Anterior vaginal wall tissue was collected from women with SUI and control subjects. Immunohistochemistry and Western blotting were performed for p-ERK1/2. Primary vaginal fibroblast cultures were incubated in the presence or absence of PD98059 (an inhibitor of ERK kinase) and levels of collagen I and III mRNA and protein were examined by quantitative reverse transcription–polymerase chain reaction and Western blot, respectively.

Results:

Levels of p-ERK1/2 were significantly lower in vaginal wall tissue from patients with SUI ( n = 10) compared with controls ( n = 10). PD98059 treatment significantly reduced levels of collagen I and III mRNA and protein.

Conclusions:

Female SUI is associated with reduced levels of p-ERK1/2 compared with controls, and inhibition of the ERK1/2 signalling pathway inhibits collagen type I and III synthesis in vaginal wall fibroblasts.

Waking up the sleepers: shared transcriptional pathways in axonal regeneration and neurogenesis

In the last several years, relevant progress has been made in our understanding of the transcriptional machinery regulating CNS repair after acute injury, such as following trauma or stroke. In order to survive and functionally reconnect to the synaptic network, injured neurons activate an intrinsic rescue program aimed to increase their plasticity. Perhaps, in the attempt to switch back to a plastic and growth-competent state, post-mitotic neurons wake up and re-express a set of transcription factors that are also critical for the regulation of their younger brothers, the neural stem cells. Here, we review and discuss the transcriptional pathways regulating both axonal regeneration and neurogenesis highlighting the connection between the two. Clarification of their common molecular substrate may help simultaneous targeting of both neurogenesis and axonal regeneration with the hope to enhance functional recovery following CNS injury.