Valproic acid induces differentiation and inhibition of proliferation in neural progenitor cells via the beta-catenin-Ras-ERK-p21Cip/WAF1 pathway

Role of an interdependent Wnt, GSK3-β/β-catenin and HB-EGF/EGFR mechanism in arsenic-induced hippocampal neurotoxicity in adult mice

We previously reported the neurotoxic effects of arsenic in the hippocampus. Here, we explored the involvement of Wnt pathway, which contributes to neuronal functions. Administering environmentally relevant arsenic concentrations to postnatal day-60 (PND60) mice demonstrated a dose-dependent increase in hippocampal Wnt3a and its components, Frizzled, phospho-LRP6, Dishevelled and Axin1 at PND90 and PND120. However, p-GSK3-β(Ser9) and β-catenin levels although elevated at PND90, decreased at PND120. Additionally, treatment with Wnt-inhibitor, rDkk1, reduced p-GSK3-β(Ser9) and β-catenin at PND90, but failed to affect their levels at PND120, indicating a time-dependent link with Wnt. To explore other underlying factors, we assessed epidermal growth factor receptor (EGFR) pathway, which interacts with GSK3-β and appears relevant to neuronal functions. We primarily found that arsenic reduced hippocampal phosphorylated-EGFR and its ligand, Heparin-binding EGF-like growth factor (HB-EGF), at both PND90 and PND120. Moreover, treatment with HB-EGF rescued p-GSK3-β(Ser9) and β-catenin levels at PND120, suggesting their HB-EGF/EGFR-dependent regulation at this time point. Additionally, rDkk1, LiCl (GSK3-β-activity inhibitor), or β-catenin protein treatments induced a time-dependent recovery in HB-EGF, indicating potential inter-dependent mechanism between hippocampal Wnt/β-catenin and HB-EGF/EGFR following arsenic exposure. Fluorescence immunolabeling then validated these findings in hippocampal neurons. Further exploration of hippocampal neuronal survival and apoptosis demonstrated that treatment with rDkk1, LiCl, β-catenin and HB-EGF improved Nissl staining and NeuN levels, and reduced cleaved-caspase-3 levels in arsenic-treated mice. Supportively, we detected improved Y-Maze and Passive Avoidance performances for learning-memory functions in these mice. Overall, our study provides novel insights into Wnt/β-catenin and HB-EGF/EGFR pathway interaction in arsenic-induced hippocampal neurotoxicity.

Influence of β-catenin signaling on neurogenesis in neuropsychiatric disorders: Anxiety and depression

It has been proven that stress, mainly in the early years of life, can lead to anxiety and mood problems. Current treatments for psychiatric disorders are not enough, and some of them show intolerable side effects, emphasizing the urgent need for new treatment targets. Hence, a better understanding of the different brain networks, which are involved in the response to anxiety and depression, may evoke treatments with more specific targets. One of these targets is β-catenin that regulates brain circuits. β-Catenin has a dual response toward stress, which may influence coping or vulnerability to stress response. Indeed, β-catenin signaling involves several processes such as inflammation-directed brain repair, inflammation-induced brain damage, and neurogenesis. Interestingly, β-catenin reduction is accompanied by low neurogenesis, which leads to anxiety and depression. However, in another state, this reduction activates a compensatory mechanism that enhances neurogenesis to protect against depression but may precipitate anxiety. Thus, understanding the molecular mechanism of β-catenin could enhance our knowledge about anxiety and depression's pathophysiology, potentially improving clinical results by targeting it. Herein, the different states of β-catenin were discussed, shedding light on possible drugs that showed action on psychiatric disorders through β-catenin.

Understanding the role of AMPA receptors in autism: insights from circuit and synapse dysfunction

Autism spectrum disorders represent a diverse etiological spectrum that converge on a syndrome characterized by discrepant deficits in developmental domains often highlighted by concerns in socialization, sensory integration, and autonomic functioning. Importantly, the incidence and prevalence of autism spectrum disorders have seen sharp increases since the syndrome was first described in the 1940s. The wide etiological spectrum and rising number of individuals being diagnosed with the condition lend urgency to capturing a more nuanced understanding of the pathogenic mechanisms underlying the autism spectrum disorders. The current review seeks to understand how the disruption of AMPA receptor (AMPAr)-mediated neurotransmission in the cerebro-cerebellar circuit, particularly in genetic autism related to SHANK3 or SYNGAP1 protein dysfunction function and autism associated with in utero exposure to the anti-seizure medications valproic acid and topiramate, may contribute to the disease presentation. Initially, a discussion contextualizing AMPAr signaling in the cerebro-cerebellar circuitry and microstructural circuit considerations is offered. Subsequently, a detailed review of the literature implicating mutations or deletions of SHANK3 and SYNGAP1 in disrupted AMPAr signaling reveals how bidirectional pathogenic modulation of this key circuit may contribute to autism. Finally, how pharmacological exposure may interact with this pathway, via increased risk of autism diagnosis with valproic acid and topiramate exposure and potential treatment of autism using AMPAr modulator perampanel, is discussed. Through the lens of the review, we will offer speculation on how neuromodulation may be used as a rational adjunct to therapy. Together, the present review seeks to synthesize the disparate considerations of circuit understanding, genetic etiology, and pharmacological modulation to understand the mechanistic interaction of this important and complex disorder.

Three Decades of Valproate: A Current Model for Studying Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with increased prevalence and incidence in recent decades. Its etiology remains largely unclear, but it seems to involve a strong genetic component and environmental factors that, in turn, induce epigenetic changes during embryonic and postnatal brain development. In recent decades, clinical studies have shown that inutero exposure to valproic acid (VPA), a commonly prescribed antiepileptic drug, is an environmental factor associated with an increased risk of ASD. Subsequently, prenatal VPA exposure in rodents has been established as a reliable translational model to study the pathophysiology of ASD, which has helped demonstrate neurobiological changes in rodents, non-human primates, and brain organoids from human pluripotent stem cells. This evidence supports the notion that prenatal VPA exposure is a valid and current model to replicate an idiopathic ASD-like disorder in experimental animals. This review summarizes and describes the current features reported with this animal model of autism and the main neurobiological findings and correlates that help elucidate the pathophysiology of ASD. Finally, we discuss the general framework of the VPA model in comparison to other environmental and genetic ASD models.

BML-281 promotes neuronal differentiation by modulating Wnt/Ca2+ and Wnt/PCP signaling pathway

Histone deacetylase (HDAC) inhibitors promote differentiation through post-translational modifications of histones. BML-281, an HDAC6 inhibitor, has been known to prevent tumors, acute dextran sodium sulfate-associated colitis, and lung injury. However, the neurogenic differentiation effect of BML-281 is poorly understood. In this study, we investigated the effect of BML-281 on neuroblastoma SH-SY5Y cell differentiation into mature neurons by immunocytochemistry (ICC), reverse transcriptase PCR (RT-PCR), quantitative PCR (qPCR), and western blotting analysis. We found that the cells treated with BML-281 showed neurite outgrowth and morphological changes into mature neurons under a microscope. It was confirmed that the gene expression of neuronal markers (NEFL, MAP2, Tuj1, NEFH, and NEFM) was increased with certain concentrations of BML-281. Similarly, the protein expression of neuronal markers (NeuN, Synaptophysin, Tuj1, and NFH) was upregulated with BML-281 compared to untreated cells. Following treatment with BML-281, the expression of Wnt5α increased, and downstream pathways were activated. Interestingly, both Wnt/Ca2+ and Wnt/PCP pathways activated and regulated PKC, Cdc42, RhoA, Rac1/2/3, and p-JNK. Therefore, BML-281 induces the differentiation of SH-SY5Y cells into mature neurons by activating the non-canonical Wnt signaling pathway. From these results, we concluded that BML-281 might be a novel drug to differentiation into neuronal cells through the regulation of Wnt signaling pathway to reduce the neuronal cell death.

Effects of HDAC inhibitors on neuroblastoma SH-SY5Y cell differentiation into mature neurons via the Wnt signaling pathway

Histone deacetylase (HDAC) inhibitors affect cell homeostasis, gene expression, and cell cycle progression and promote cell terminal differentiation or apoptosis. However, the effect of HDAC inhibition on SH-SY5Y cells, which are neuroblastoma cells capable of differentiating into neurons under specific conditions, such as in the presence of retinoic acid (RA), is unknown. In this study, we hypothesized that HDAC inhibitors induced the neuronal differentiation of SH-SY5Y cells. To test this hypothesis, we used phase contrast microscopy, immunocytochemistry (ICC), qPCR, and western blotting analysis. MS-275 and valproic acid (VPA), two HDAC inhibitors, were selected to evaluate neuronal differentiation. It was confirmed that cells treated with MS-275 or VPA differentiated into mature neurons, which were distinguished by bipolar or multipolar morphologies with elongated branches. In addition, the mRNA expression of neuronal markers (Tuj1 and NEFH) and the oligodendrocyte marker (CNP) was significantly increased with MS-275 or VPA treatment compared to that with RA treatment. In addition, the protein expression of the other neuronal markers, Tuj1 and NeuN, was highly increased with HDAC inhibitor treatments compared to that with RA treatment. Furthermore, we confirmed that noncanonical Wnt signaling was upregulated by HDAC inhibitors via MAPK signaling and the Wnt/JNK pathway. Therefore, both MS-275 and VPA promoted the differentiation of SH-SY5Y cells into mature neurons via the Wnt signaling pathway.

Valproic acid exposure decreases neurogenic potential of outer radial glia in human brain organoids

Valproic acid (VPA) exposure during pregnancy leads to a higher risk of autism spectrum disorder (ASD) susceptibility in offspring. Human dorsal forebrain organoids were used to recapitulate course of cortical neurogenesis in the developing human brain. Combining morphological characterization with massive parallel RNA sequencing (RNA-seq) on organoids to analyze the pathogenic effects caused by VPA exposure and critical signaling pathway. We found that VPA exposure in organoids caused a reduction in the size and impairment in the proliferation and expansion of neural progenitor cells (NPCs) in a dose-dependent manner. VPA exposure typically decreased the production of outer radial glia-like cells (oRGs), a subtype of NPCs contributing to mammalian neocortical expansion and delayed their fate toward upper-layer neurons. Transcriptomics analysis revealed that VPA exposure influenced ASD risk gene expression in organoids, which markedly overlapped with irregulated genes in brains or organoids originating from ASD patients. We also identified that VPA-mediated Wnt/β-catenin signaling pathway activation is essential for sustaining cortical neurogenesis and oRGs output. Taken together, our study establishes the use of dorsal forebrain organoids as an effective platform for modeling VPA-induced teratogenic pathways involved in the cortical neurogenesis and oRGs output, which might contribute to ASD pathogenesis in the developing brain.

Valproic acid and bladder healing: an experimental study in rats

PURPOSE

to recognize the effects of valproic acid (VPA), an epigenetic drug, on the bladder healing process, in rats.

METHOD

twenty male Wistar rats were divided in two groups: experimental (A), treated with VPA (150mg/Kg/day), and control (B) with 0.9% sodium chloridrate. Healing was analyzed on the third and seventh days, evaluating the inflammatory reaction, collagen synthesis and angiogenesis.

RESULTS

inflammatory reaction on the third day was minimal and acute in both groups. On the seventh day, it was subacute in both groups, moderate intensity in group A and minimal in group B (p=0.0476). Collagen III intensity, marked by immunohistochemistry, was similar in both groups. Collagen I intensity on the third day was similar in both groups, but on the seventh day it was higher in experimental than control (p=0.0476). Collagen evaluation by picrosiriusred allowed to verify that the presence of collagen III was similar in both groups (p=0.3312) on the third day, and it was higher in control on the seventh day (p=0.0015). Collagen I showed similarity on the third day (p=0.3100), and it was higher in control on the seventh day (p=0.0015). Vessel marked with anti-SMA counting showed fewer vessels on the third (p=0.0034) and seventh day (p=0.0087) in experimental group. The lower intensity of angiogenesis was confirmed with anti-CD34, on the third day (p=0,0006) and on the seventh day (p=0,0072).

CONCLUSION

VPA determined alterations in the bladder healing process, in rats, with lower collagen density and less angiogenic activity, but without compromising the integrity of the organ.

Prenatal exposure to valproic acid alters Reelin, NGF expressing neuron architecture and impairs social interaction in their autistic-like phenotype male offspring

Maternal exposure to anti-epileptic drug Valproic acid (VPA) during pregnancy increases the risk for the development of autism spectrum disorders (ASD). In this study, we have examined whether prenatal exposure to VPA will alter expression of key genes, synaptic morphology of nerve growth factor (NGF) and Reelin expressing neurons in the cortex of male offspring. To characterize in animal models, rat fetuses were exposed to VPA on 12.5 gestational day. The offspring of the VPA-exposed individuals (42%) resembles ASD-related phenotype (facial malformation, crooked-like tail, flattened paw, toenails and in-turning-ankles). Furthermore, we have observed deficit in social interaction accompanied by deregulation in expression of genes such as Caspase-3, focal adhesion kinase (FAK), Reelin, glial fibrillary acidic protein (GFAP), proliferating cell nuclear antigen (PCNA) and NGF. Subsequently, immunohistochemistry analysis revealed that exposure to VPA alters the cytoarchitecture (area, diameter) and reduced the dendritic arborization of Reelin, NGF expressing neurons in cortex. The compromised neurodevelopment by altered expression of Caspase-3, FAK, Reelin, GFAP, PCNA and NGF may cause defects in neuronal architecture, synaptic formation, synaptic plasticity and neuronal communication which could be linked with observed ASD-like phenotype and deficit social interaction.

A Small Molecule Promoting Neural Differentiation Suppresses Cancer Stem Cells in Colorectal Cancer

Cancer stem cells (CSCs) are a tumor cell subpopulation that drives tumor progression and metastasis, leading to a poor overall survival of patients. In colorectal cancer (CRC), the hyper-activation of Wnt/β-catenin signaling by a mutation of both adenomatous polyposis coli (APC) and K-Ras increases the size of the CSC population. We previously showed that CPD0857 inactivates Wnt/β-catenin signaling by promoting the ubiquitin-dependent proteasomal degradation of β-catenin and Ras proteins, thereby decreasing proliferation and increasing the apoptosis of CRC lines. CPD0857 also decreased the growth and invasiveness of CRC cells harboring mutant K-Ras resistant to EGFR mAb therapy. Here, we show that CPD0857 treatment decreases proliferation and increases the neuronal differentiation of neural progenitor cells (NPCs). CDP0857 effectively reduced the expression of CSC markers and suppressed self-renewal capacity. CPD0857 treatment also inhibited the proliferation and expression of CSC markers in D-K-Ras MT cells carrying K-Ras, APC and PI3K mutations, indicating the inhibition of PI3K/AKT signaling. Moreover, CPD0857-treated xenograft mice showed a regression of tumor growth and decreased numbers of CSCs in tumors. We conclude that CPD0857 could serve as the basis of a drug development strategy targeting CSCs activated through Wnt/β-catenin-Ras MAPK-PI3K/AKT signaling in CRCs.

Human forebrain organoids reveal connections between valproic acid exposure and autism risk

Valproic acid (VPA) exposure as an environmental factor that confers risk of autism spectrum disorder (ASD), its functional mechanisms in the human brain remain unclear since relevant studies are currently restricted to two-dimensional cell cultures and animal models. To identify mechanisms by which VPA contribute to ASD risk in human, here we used human forebrain organoids (hFOs), in vitro derived three-dimensional cell cultures that recapitulate key human brain developmental features. We identified that VPA exposure in hFOs affected the expression of genes enriched in neural development, synaptic transmission, oxytocin signaling, calcium, and potassium signaling pathways, which have been implicated in ASD. Genes (e.g., CAMK4, CLCN4, DPP10, GABRB3, KCNB1, PRKCB, SCN1A, and SLC24A2) that affected by VPA were significantly overlapped with those dysregulated in brains or organoids derived from ASD patients, and known ASD risk genes, as well as genes in ASD risk-associated gene coexpression modules. Single-cell RNA sequencing analysis showed that VPA exposure affected the expression of genes in choroid plexus, excitatory neuron, immature neuron, and medial ganglionic eminence cells annotated in hFOs. Microelectrode array further identified that VPA exposure in hFOs disrupted synaptic transmission. Taken together, this study connects VPA exposure to ASD pathogenesis using hFOs, which is valuable for illuminating the etiology of ASD and screening for potential therapeutic targets.

Duloxetine ameliorates valproic acid-induced hyperactivity, anxiety-like behavior, and social interaction deficits in zebrafish

Syndromic autism spectrum disorders (ASDs) are characterized by impaired social communication and repetitive/stereotyped behaviors. Currently available therapeutic agents against ASD have limited efficacy. Thus, searching for novel and effective drugs ameliorating core symptoms, in particular social deficits, is of utmost importance. Duloxetine (DLX), an antidepressant that has been identified as an agonist mimetic for the cell adhesion molecule L1, exhibits beneficial functions in vitro and in vivo. Therefore, in this study, we focused on the rapid and persistent neuroprotective function of DLX following valproic acid (VPA)-triggered hyperactivity, anxiety-like behavior and social deficits in zebrafish. Embryonic exposure to VPA reduced survival in a dose- and time-dependent manner, delayed hatching, and also resulted in a significant number of malformed larvae. After initial dose-response experiments in zebrafish larvae, 10 μM VPA exposure between 0.33 and 4.5 days post fertilization (dpf) was identified as an effective concentration that led to an early and persistent ASD-like phenotype in zebrafish. ASD-like elevated acetylcholine esterase (AChE) activity and reduced Akt-mTOR signaling was observed in zebrafish whole brain. Acute administration of DLX (4.5-6 dpf) reduced the VPA-induced ASD-like phenotype in zebrafish larvae. Additionally, such early-life acute DLX treatment had long-term effects in ameliorating social impairments, hyperactivity, and anxiety-like behaviors through adulthood. This was accompanied by reduced AChE activity and by normalized Akt-mTOR signaling. Overall, DLX treatment showed a long-term therapeutic effect on autistic-like behaviors, and alteration of AChE activity and Akt-mTOR signaling were identified as crucial in the VPA-induced ASD zebrafish model.

Valproic acid enhances neurosphere formation in cultured rat embryonic cortical cells through TGFβ1 signaling

This study aimed to investigate the effect and mechanism of valproic acid (VPA) on the neurosphere formation in rat embryonic cortical cells. We used free-floating neurosphere formation as a model system to evaluate the VPA on the proliferation of neural stem cells (NSCs). We found a time- and dose-dependent increase in neurosphere formation and NSC proliferation after VPA treatment. Further RNA-seq analysis demonstrated that the upregulated TGFβ1 signaling might attribute to the effect of VPA on the neurosphere formation and NSC proliferation. Consistently, the neurosphere formation and NSC proliferation were blocked by the treatment with SB431542, an inhibitor of TGFβ1 receptor. Moreover, in a coculture system, NSCs treated with VPA significantly reduced the oxygen-glucose deprivation-induced neuronal apoptosis. Taken together, our results showed that VPA could enhance neurosphere formation and NSC proliferation by activating TGFβ1, which might be a novel therapeutic strategy for neurological disorders.

Ácido valpróico e cicatrização em bexiga: estudo experimental em ratos

RESUMO Objetivo: reconhecer os efeitos do ácido valpróico (VPA), uma droga epigenética, no processo de cicatrização da bexiga, em ratos. Método: vinte ratos Wistar machos foram divididos em dois grupos: experimental (A), utilizando VPA (150mg/Kg/dia), e controle (B), tratados com cloreto de sódio 0,9% por gavagem. A cicatrização da bexiga foi analisada no terceiro e sétimo dia, estudando-se a reação inflamatória, síntese de colágeno, reepitelização e angiogênese. Resultados: a reação inflamatória no terceiro dia foi mínima e aguda em ambos os grupos. No sétimo dia, foi subaguda em ambos os grupos com intensidade moderada no grupo A e mínima no grupo B (p=0,0476). A intensidade do colágeno III, marcada pela imuno-histoquímica, foi semelhante nos dois grupos, nos dois tempos estudados. A intensidade de colágeno I no terceiro dia foi semelhante nos dois grupos, e maior no sétimo dia no grupo experimental (p=0,0476). A avaliação do colágeno pelo picrosiriusred mostrou que a presença de colágeno III foi semelhante em ambos os grupos (p=0,3312) no terceiro dia, e maior no controle no sétimo dia (p=0,0015). O colágeno I foi semelhante no terceiro dia (p=0,3100), e maior no controle no sétimo dia (p=0,0015). A contagem de vasos marcados pelo anti-SMA mostrou menos vasos no terceiro (p=0,0034) e sétimo dia (p=0,0087) no grupo experimental, confirmado pelo anti-CD34, no terceiro (p=00006) e no sétimo dia (p=0,0072). Conclusão: o VPA determinou alterações no processo de cicatrização da bexiga, em ratos, com menor densidade de colágeno e menor atividade angiogênica, mas sem comprometer a integridade do órgão.

Melatonin Ameliorates Valproic Acid-Induced Neurogenesis Impairment: The Role of Oxidative Stress in Adult Rats

Background

Valproic acid (anticonvulsant medication) has been found to inhibit histone deacetylase activity and suppress hippocampal neurogenesis, which causes memory impairment in both humans and rodents. The neurohormone melatonin, which regulates mammalian seasonal and circadian physiology, has recently been shown to have neuroprotective properties, counteracting memory impairment associated with VPA-caused hippocampal neurogenesis reduction. This study is aimed at investigating the molecular mechanisms of melatonin associated with VPA-induced hippocampal neurogenesis and memory impairment.

Methods

Male Spraque-Dawley rats received VPA (300 mg/kg) twice daily or melatonin (8 mg/kg/day) or some rats were given melatonin for 14 days during VPA administration.

Results

The VPA-treated rats showed a significant increase in malondialdehyde (MDA) levels in the hippocampus and p21-positive cells in the subgranular zone (SGZ) of the dentate gyrus (DG) but decreased superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) activities. Moreover, VPA significantly decreased levels of nestin, Notchl, nuclear factor erythroid 2-related factor 2 (Nrf2), doublecortin (DCX), sex determining region Y-box 2 (SOX2), and brain-derived neurotrophic factor (BDNF).

Conclusions

We found that melatonin was able to counteract these neurotoxic effects, acting as a neuroprotectant in VPA-induced memory hippocampal neurogenesis impairment by preventing intracellular oxidative stress and increasing antioxidant activity.

Criss-crossing autism spectrum disorder and adult neurogenesis

Autism spectrum disorder (ASD) comprises a group of multifactorial neurodevelopmental disorders primarily characterized by deficits in social interaction and repetitive behavior. Although the onset is typically in early childhood, ASD poses a lifelong challenge for both patients and caretakers. Adult neurogenesis (AN) is the process by which new functional neurons are created from neural stem cells existing in the post-natal brain. The entire event is based on a sequence of cellular processes, such as proliferation, specification of cell fate, maturation, and ultimately, synaptic integration into the existing neural circuits. Hence, AN is implicated in structural and functional brain plasticity throughout life. Accumulating evidence shows that impaired AN may underlie some of the abnormal behavioral phenotypes seen in ASD. In this review, we approach the interconnections between the molecular pathways related to AN and ASD. We also discuss existing therapeutic approaches targeting such pathways both in preclinical and clinical studies. A deeper understanding of how ASD and AN reciprocally affect one another could reveal important converging pathways leading to the emergence of psychiatric disorders.

Valproic acid and Propionic acid modulated mechanical pathways associated with Autism Spectrum Disorder at prenatal and neonatal exposure

Autism Spectrum Disorder (ASD) is a composite disorder of brain development with uncertain etiology and pathophysiology. Genetic factors are important in ASD causation, although environmental factors are also involved in ASD pathophysiology. Environmental factors might affect the genetic processes of brain development through the modulation of molecular pathways that might be involved with ASD. Valproic acid and Propionic acid are the major environmental factors that serve as medicine and food preservative. VPA is used as an anti-epileptic medicine, but it has adverse effects on pregnant women and alters the developmental patterns of the embryo. It is a multi-targeting agent and affects through the 5-HT, GABA, etc. PPA is a secondary metabolite of gut microbiota that is commonly used as a food preservative. PPA plays a significant role in ASD causation by altering the several developmental molecular pathways like PTEN/Akt, mTOR/Gskβ, Cytokines activated pathways, etc., at the prenatal and neonatal stage. Moreover, ASD complexity might be increased by some other important factors like vitamin A deficiency and Vitamin A is important for cortical brain development and neuronal cell differentiation. Additionally, several important genes such as RELN, Lhx2, CREB, IL-6, NMDA, BDNF, etc. also altered in ASD that involved in brain development, Central Nervous System, Enteric Nervous System. These genes affect the neuronal differentiation, hyperactivity, oxidative stress, oxytocin, and GABA imbalance that lead the improper behavior in autistic individuals. These genes are also studied in VPA and PPA ASD-like animal models. In this review, we explored the mechanical pathways that might be altered with VPA and PPA exposures at the embryonic developmental stage or neonatal developmental stage.

Valproic acid up-regulates the whole NO-citrulline cycle for potent iNOS-NO signaling to promote neuronal differentiation of adipose tissue-derived stem cells

Valproic acid (VPA) remarkably promotes the differentiation of adipose tissue-derived stem cells (ASCs) to mature neuronal cells through nitric oxide (NO) signaling due to up-regulated inducible NO synthase (iNOS) as early as within 3 days. Here, we investigated mechanisms of VPA-promoted neuronal differentiation of ASCs concerning the NO-citrulline cycle, the metabolic cycle producing NO. Cultured rat ASCs were differentiated to mature neuronal cells rich in dendrites and expressing a neuronal marker by treatments with VPA at 2 mM for 3 days and subsequently with the neuronal induction medium for 2 h. Inhibitor (α-methyl-d, l-aspartic acid, MDLA) of arginosuccinate synthase (ASS), a key enzyme of the NO-citrulline cycle, abolishes intracellular NO increase and VPA-promoted neuronal differentiation in ASCs. l-Arginine, the substrate of iNOS, restores the promotion effect of VPA, being against MDLA. Immunocytochemistry showed that ASS and iNOS were increased in ASCs expressing neurofilament medium polypeptide (NeFM), a neuronal marker, by VPA and NIM synergistically. Real-time RT-PCR analysis showed that mRNAs of Ass and arginosuccinate lyase (Asl) in the NO-citrulline cycle were increased by VPA. Chromatin immunoprecipitation assay indicated that Ass and Asl were up-regulated by VPA through the acetylation of their associated histone. From these results, it was considered that VPA up-regulated the whole NO-citrulline cycle, which enabled continuous NO production by iNOS in large amounts for potent iNOS-NO signaling to promote neuronal differentiation of ASCs. This may also indicate a mechanism enabling short-lived NO to function conveniently as a potent signaling molecule that can disappear quickly after its role.

The anti-epileptic drug valproic acid causes malformations in the developing craniofacial skeleton of zebrafish larvae

Valproic acid (VPA) is an anti-epileptic drug known to cause congenital craniofacial abnormalities, including orofacial clefts (OFC). The exact mechanisms by which VPA leads to craniofacial skeletal malformations are poorly understood. In this study, we investigated the effects of VPA on cartilage and bone formation in the zebrafish larval head during 1-13 hpf (early) and 25-37 hpf (late) development in which cranial neural crest cells (CNCCs) arise and then proliferate and differentiate, respectively. Double-staining for cartilage and bone at 5 dpf revealed that VPA reduced cartilage and bone formation in a dose-dependent manner after both early or late exposure. Several different CNCC-derived cartilage and bone elements were affected in both groups. In the early group (100 μM VPA), the posterior head length and the ethmoid plate were reduced in length (both p < 0.01), while mineralization of 4 out of 9 bone elements was often lacking (all p < 0.01). In the late group (100 μM VPA), also the posterior head length was reduced as well as the length of the ceratohyals (both p < 0.01). Similar to early exposure, mineralization of 3 out of 9 bone elements was often lacking (all p < 0.01). These results indicate that both CNCC formation (early) and differentiation (late) are hampered by VPA treatment, of which the consequences for bone and cartilage formation are persistent at 5 dpf. Indeed, we also found that the expression of several genes related to cartilage and bone was upregulated at 5 dpf. These data indicate a compensatory reaction to the lack of cartilage and bone. Altogether, VPA seems to induce craniofacial malformations via disturbed CNCC function leading to defects in cartilage and bone formation.

Histone Deacetylases Inhibitors in Neurodegenerative Diseases, Neuroprotection and Neuronal Differentiation

Histone deacetylases (HADC) are the enzymes that remove acetyl group from lysine residue of histones and non-histone proteins and regulate the process of transcription by binding to transcription factors and regulating fundamental cellular process such as cellular proliferation, differentiation and development. In neurodegenerative diseases, the histone acetylation homeostasis is greatly impaired, shifting towards a state of hypoacetylation. The histone hyperacetylation produced by direct inhibition of HDACs leads to neuroprotective actions. This review attempts to elaborate on role of small molecule inhibitors of HDACs on neuronal differentiation and throws light on the potential of HDAC inhibitors as therapeutic agents for treatment of neurodegenerative diseases. The role of HDACs in neuronal cellular and disease models and their modulation with HDAC inhibitors are also discussed. Significance of these HDAC inhibitors has been reviewed on the process of neuronal differentiation, neurite outgrowth and neuroprotection regarding their potential therapeutic application for treatment of neurodegenerative diseases.

Gene expression changes induced by valproate in the process of rat hippocampal neural stem cells differentiation

Valproate (VPA), an effective clinical approved anti-epileptic drug and mood stabilizer, has been believed to induce neuronal differentiation at the expense of inhibiting astrocytic and oligodendrocytic differentiation. Nevertheless, the involving mechanisms of it remain unclear yet. In the present study, we explored the global gene expression changes of fetus rat hippocampal neural stem cells following VPA treatment by high-throughput microarray. We obtained 874 significantly upregulated genes and 258 obviously downregulated genes (fold change > 2 and P < 0.05). Then, we performed gene ontology and pathway analyses of these differentially expressed genes and chose several genes associated with nervous system according to gene ontology analysis to conduct expression analysis to validate the reliability of the array results as well as reveal possible mechanisms of VPA. To get a better comprehension of the differentially regulated genes by VPA, we conducted protein-protein association analysis of these genes, which offered a source for further studies. In addition, we made the overlap between the VPA-downregulated genes and the predicted target genes of VPA-upregulated microRNAs (miRNAs), which were previously demonstrated. These overlapped genes may provide a source to find functional VPA/miRNA/mRNA axes during neuronal differentiation. This study first constructed a comprehensive potential downstream gene map of VPA in the process of neuronal differentiation.

Crafting Carbazole-Based Vorinostat and Tubastatin-A-like Histone Deacetylase (HDAC) Inhibitors with Potent in Vitro and in Vivo Neuroactive Functions

Small-molecule inhibitors of HDACs (HDACi) induce hyperacetylation of histone and nonhistone proteins and have emerged as potential therapeutic agents in most animal models tested. The established HDACi vorinostat and tubastatin-A alleviate neurodegenerative and behavioral conditions in animal models of neuropsychiatric disorders restoring the neurotrophic milieu. In spite of the neuroactive pharmacological role of HDACi (vorinostat and tubastatin-A), they are limited by efficacy and toxicity. Considering these limitations and concern, we have designed novel compounds 3-11 as potential HDACi based on the strategic crafting of the key pharmacophoric elements of vorinostat and tubastatin-A into architecting a single molecule. The molecules 3-11 were synthesized through a multistep reaction sequence starting from carbazole and were fully characterized by NMR and mass spectral analysis. The novel molecules 3-11 showed remarkable pan HDAC inhibition and the potential to increase the levels of acetyl H3 and acetyl tubulin. In addition, few novel HDAC inhibitors 4-8, 10, and 11 exhibited significant neurite outgrowth-promoting activity with no observable cytotoxic effects, and interestingly, compound 5 has shown comparably more neurite growth than the parent compounds vorinostat and tubastatin-A. Also, compound 5 was evaluated for possible mood-elevating effects in a chronic unpredictable stress model of Zebrafish. It showed potent anxiolytic and antidepressant-like effects in the novel tank test and social interaction test, respectively. Furthermore, the potent in vitro and in vivo neuroactive compound 5 has shown selectivity for class II over class I HDACs. Our results suggest that the novel carbazole-based HDAC inhibitors, crafted with vorinostat and tubastatin-A pharmacophoric moieties, have potent neurite outgrowth activity and potential to be developed as therapeutics to treat depression and related psychiatric disorders.

Probing disrupted neurodevelopment in autism using human stem cell-derived neurons and organoids: An outlook into future diagnostics and drug development

Autism spectrum disorders (ASDs) represent a spectrum of neurodevelopmental disorders characterized by impaired social interaction, repetitive or restrictive behaviors, and problems with speech. According to a recent report by the Centers for Disease Control and Prevention, one in 68 children in the US is diagnosed with ASDs. Although ASD-related diagnostics and the knowledge of ASD-associated genetic abnormalities have improved in recent years, our understanding of the cellular and molecular pathways disrupted in ASD remains very limited. As a result, no specific therapies or medications are available for individuals with ASDs. In this review, we describe the neurodevelopmental processes that are likely affected in the brains of individuals with ASDs and discuss how patient-specific stem cell-derived neurons and organoids can be used for investigating these processes at the cellular and molecular levels. Finally, we propose a discovery pipeline to be used in the future for identifying the cellular and molecular deficits and developing novel personalized therapies for individuals with idiopathic ASDs.

Harnessing the HDAC-histone deacetylase enzymes, inhibitors and how these can be utilised in tissue engineering

There are large knowledge gaps regarding how to control stem cells growth and differentiation. The limitations of currently available technologies, such as growth factors and/or gene therapies has led to the search of alternatives. We explore here how a cell’s epigenome influences determination of cell type, and potential applications in tissue engineering. A prevalent epigenetic modification is the acetylation of DNA core histone proteins. Acetylation levels heavily influence gene transcription. Histone deacetylase (HDAC) enzymes can remove these acetyl groups, leading to the formation of a condensed and more transcriptionally silenced chromatin. Histone deacetylase inhibitors (HDACis) can inhibit these enzymes, resulting in the increased acetylation of histones, thereby affecting gene expression. There is strong evidence to suggest that HDACis can be utilised in stem cell therapies and tissue engineering, potentially providing novel tools to control stem cell fate. This review introduces the structure/function of HDAC enzymes and their links to different tissue types (specifically bone, cardiac, neural tissues), including the history, current status and future perspectives of using HDACis for stem cell research and tissue engineering, with particular attention paid to how different HDAC isoforms may be integral to this field.

Positive effects of α-asarone on transplanted neural progenitor cells in a murine model of ischemic stroke

BACKGROUND

Some traditional Oriental herbal medicines, such as Acorus tatarinowii and Acorus gramineus, produce beneficial effects for cognition enhancement. An active compound in rhizomes and the bark of these plants is α-asarone.

PURPOSE

This study investigated the effects of α-asarone on the proliferation and differentiation of neural progenitor cells (NPCs) in a primary culture and a murine model of ischemic stroke.

METHODS

NPCs were isolated from mouse fetal cerebral cortices on embryonic day 15, and all experiments were performed using passage 3 NPCs. We utilized a cell counting kit-8 assay, flow cytometry, western blot, and immunohistochemical analysis to assess proliferation and differentiation of NPCs and employed α-asarone in NPC transplanted ischemic stroke mice to evaluate stroke-related functional recovery using behavioral and immunohistochemical analysis.

RESULT

Treatment with 1 µM, 3 µM, or 10 μM α-asarone induced significant NPC proliferation compared to vehicle treatment. Induced NPCs expressed the neuronal marker neuronal nuclei (NeuN) or the astrocyte marker S100 calcium-binding protein B (S100β). Both immunohistochemistry and flow cytometry revealed that treatment with α-asarone increased the number of NeuN-immunoreactive cells and decreased the number of S100β-immunoreactive cells. Treatment with α-asarone also increased the expression of β-catenin, cyclin D1, and phosphorylated extracellular signal-regulated kinase (ERK) compared to vehicle treatment. In a murine model of ischemic stroke, treatment with α-asarone and transplanted NPCs alleviated stroke-related functional impairments. The corner and rotarod test results revealed that treatment with α-asarone in the NPC transplanted group had greater-than-additive effects on sensorimotor function and motor balance. Moreover, α-asarone treatment promoted the differentiation of transplanted NPCs into NeuN-, glial fibrillary acidic protein (GFAP)-, platelet-derived growth factor-α (PDGFR-α)-, and 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)-immunoreactive cells.

CONCLUSION

α-asarone may promote NPC proliferation and differentiation into neuron-lineage cells by activating β-catenin, cyclin D1, and ERK. Moreover, α-asarone treatment facilitated neurofunctional recovery after NPC transplantation in a murine model of ischemic stroke. Therefore, α-asarone is a potential adjunct treatment to NPC therapy for functional restoration after brain injuries such as ischemic stroke.

Effect of Lithium and Valproate on Proliferation and Migration of Limbal Epithelial Stem/Progenitor Cells

PURPOSE

The effects of lithium (Li) and Valproic Acid (VA) drugs have been recently revealed to improve the Mesenchymal stem cells')MSCs (migration and proliferation processes. The aim of this study is to determine the expression of the genes involved in the proliferation and migration of limbal epithelial stem/progenitor cells (LESPCs) after treatment with Li and VA.

METHODS

After extraction of LSCs from human Corneoscleral tissue, cells were subcultured three times. The cell culture media were divided into four separate groups including groups treated with VA, Li, combination, and control groups after determining the non-toxic concentration of drugs (64mml) Li and (28mml) VA based on MTT assay, and then cells cultures were treated for 3 hours. A real-time polymerase chain reaction was performed to detect the expression levels of CD44, Ki67, CXCR4, CXCR7, MMP-2, MMP-9, and SDF-1 genes. Changes in the expression of each gene in different treatments were calculated. Finally, the graphs were analyzed by SPSS (Version 18) software.

RESULTS

The highest expression of CXCR4 and CXCR7 was in the Li-treated group. Additionally, the highest expression levels of MMP-9 and CD44 genes were observed in the VA-treated group. In contrast, the expression level of SDF-1a, MMP2, and Ki67 genes in all three treatment groups reduced compared to the control group.

CONCLUSION

Increasing the LSCs migration genes (CXCR4 and MMP9) was more evident than cell proliferation genes (Ki67). In sum, Li and VA can affect the process of proliferation and migration of LSCs in vitro.

Neonatal Oxytocin Treatment Ameliorates Autistic-Like Behaviors and Oxytocin Deficiency in Valproic Acid-Induced Rat Model of Autism

Autism spectrum disorder (ASD) is characterized by impaired social communication and repetitive/stereotyped behaviors. The neuropeptide oxytocin (OXT) plays a critical role in regulating social behaviors in the central nervous system, as indicated in both human and animal studies. We hypothesized that central OXT deficit is one of causes of etiology of ASD, which may be responsible for the social impairments. To test our hypothesis, central OXT system was examined in valproic acid (VPA)-induced rat model of autism (VPA rat). Our results showed that adolescent VPA rats exhibited a lower level of OXT mRNA and fewer OXT-ir cells in the hypothalamus than control rats. Additionally, OXT concentration in cerebrospinal fluid (CSF) was reduced. The number of OXT-ir cells in the supraoptic nucleus (SON) of neonatal VPA rats was also lower. Autistic-like behaviors were observed in these animals as well. We found that an acute intranasal administration of exogenous OXT restored the social preference of adolescent VPA rats. Additionally, early postnatal OXT treatment had long-term effects ameliorating the social impairments and repetitive behaviors of VPA rats until adolescence. This was accompanied by an increase in OXT-ir cells. Taken together, we demonstrated there was central OXT deficiency in the VPA-induced rat model of autism, and showed evidence that early postnatal OXT treatment had a long-term therapeutic effect on the autistic-like behaviors in VPA rats.

Valproic acid promotes the neuronal differentiation of spiral ganglion neural stem cells with robust axonal growth

Hearing loss occurs with the loss of hair cells of the cochlea and subsequent degeneration of spiral ganglion neurons (SGNs). Regeneration of SGNs is a potentially promising therapeutic approach to hearing loss in addition to the use of a cochlear implant (CI), because this device stimulates SGNs directly to restore hearing bypassing the missing hair cells. The presence of SGN-neural stem cells (NSCs) has been reported in adult human and mice. These cells have the potential to become SGNs and thus represent a cellular foundation for regeneration therapies for hearing loss. Valproic acid (VPA) has been shown to influence the neural differentiation of NSCs through multiple signaling pathways involving glycogen synthase kinase3β (GSK3β). Our present study therefore aimed to modulate the neural differentiation potential of SGN-NSCs by treatment with VPA. We here report that a clinically relevant concentration of 1 mM VPA induced the differentiation of basic fibroblast growth factor (bFGF)-treated P1- and P14-SGN-NSCs into neuronal and glial cells, confirmed by neuronal marker (Tuj1 and MAP2) and glial cell marker (GFAP and S100β) detection. VPA-treated cells also promoted much longer neurite outgrowth compared to differentiated cells cultured without bFGF. The effects of VPA on the regulation of differentiation may be related to the activation of the Wnt/β-catenin signaling pathway, but not the inhibition of histone deacetylases (HDACs). We propose that VPA has the potential to convert SGN-NSCs into SGNs and thereby restore hearing when combined with a CI.

Transcutaneous implantation of valproic acid-encapsulated dissolving microneedles induces hair regrowth

The interest in alternative material systems and delivery methods for treatment of androgenetic alopecia has been increasing in the recent decades. Topical application of valproic acid (VPA), an FDA-approved anticonvulsant drug, has been shown to effectively stimulate hair follicle (HF) regrowth by upregulating Wnt/β-catenin, a key pathway involved in initiation of HF development. Moreover, a majority of studies have suggested that cutaneous wound re-epithelialization is capable of inducing HF through Wnt/β-catenin pathway. Here, we report fabrication and evaluation of a novel VPA-encapsulating dissolving microneedle (DMN-VPA) that creates minimally invasive dermal micro-wounds upon application, significantly improving the VPA delivery efficiency. DMN-VPA not only delivers encapsulated VPA with higher accuracy than topical application, it also stimulates wound re-epithelialization signals involved in HF regrowth. Through a series of in vivo studies, we show that micro-wounding-mediated implantation of DMN-VPA upregulates expression of Wnt/β-catenin pathway, alkaline phosphatase, proliferating cell nuclear antigen, loricrin and HF stem cell markers, including keratin 15, and CD34 more effectively than topical application.

Fluid shear stress induces osteoblast differentiation and arrests the cell cycle at the G0 phase via the ERK1/2 pathway

Numerous studies have demonstrated that fluid shear stress (FSS) may promote the proliferation and differentiation of osteoblast cells. However, proliferation and differentiation are mutually exclusive processes and are unlikely to be promoted by FSS simultaneously. Cell proliferation and differentiation induced by FSS has rarely been reported. In order to provide an insight into this process, the present study investigated the effects of FSS on osteoblast‑like MC3T3 cells in the G0/G1 phase, the period during which the fate of a cell is determined. The results of the present study demonstrated that FSS promoted alkaline phosphatase (ALP) activity, and the mRNA expression and protein expression of osteocalcin, collagen type I and runt‑related transcription factor 2 (Runx2), while inhibiting DNA synthesis and arresting the cell cycle at the G0/G1 phase. The increase in Runx2 and ALP activity was accompanied by the activation of calcium/calmodulin‑dependent protein kinase type II (CaMK II) and extracellular signal‑regulated kinases 1/2 (ERK1/2), which was completely abolished by treatment with KN93 and U0126, respectively. In addition, the inhibition of ERK1/2, although not CaMK II, decreased p21Cip/Kip activity, resulting in an increase in cell number and S phase re‑entry. The results of the present study indicated that in the G0/G1 phase, FSS promoted osteoblast differentiation via the CaMK II and ERK1/2 signaling pathways, and blocked the cell cycle at the G0/G1 phase via the ERK1/2 pathway only. The present findings provided an increased understanding of osteoblastic mechanobiology.

Adverse effects of prenatal and early postnatal exposure to antiepileptic drugs: Validation from clinical and basic researches

Epilepsy requires the long-term administration of antiepileptic drugs (AEDs), and thus, we must consider the effects of prenatal AED exposure on fetus when treating female patients of child bearing age. Large prospective clinical researches in humans have demonstrated the following: (1) prenatal exposure to valproic acid (VPA), carbamazepine, and phenobarbital increases the risk of congenital malformations in a dose-dependent manner and (2) prenatal exposure to VPA increases the risk of higher brain function impairments including intellectual disabilities and autistic spectrum disorders in the offspring. Furthermore, basic researches in animals have shown that prenatal exposure to specific AEDs causes microscopic structural abnormalities in the fetal brain. Specifically, prenatal exposure to VPA has been reported to inhibit the differentiation of neural progenitor cells during the early to middle phases of neuronogenesis, leading to increased number of projection neurons in the superficial layers of postnatal neocortices in mice. It is indispensable to prescribe AEDs that are associated with lower risk of congenital malformations and impairment of higher brain functions as well as to administer them at requisite minimum doses.

New Insights into the Neural Differentiation Potential of Canine Adipose Tissue-Derived Mesenchymal Stem Cells

Adipose tissue-derived stem cells (ASCs) can be obtained from different adipose tissue sources within the body. It is an abundant cell pool, easily accessible, suitable for cultivation and expansion in vitro and preparation for therapeutic approaches. Amongst these therapeutic approaches are tissue engineering and nervous system disorders such as spinal cord injuries. For such treatment, ASCs have to be reliably differentiated in to the neuronal direction. Therefore, we investigated the neural differentiation potential of ASCs using protocols with neurogenic inductors such as valproic acid and forskolin, while dog brain tissue served as control. Morphological changes could already be noticed 1 h after neuronal induction. Gene expression analysis revealed that the neuronal markers nestin and βIII-tubulin as well as MAP2 were expressed after induction of neuronal differentiation. Additionally, the expression of the neurotrophic factors NGF, BDNF and GDNF was determined. Some of the neuronal markers and neurotrophic factors were already expressed in undifferentiated cells. Our findings point out that ASCs can reliably be differentiated into the neuronal lineage; therefore, these cells are a suitable cell source for cell transplantation in disorders of the central nervous system. Follow-up studies would show the clinical benefit of these cells after transplantation.

alproic Acid Modulates the Multipotency in Periodontal Ligament Stem Cells via p53-Mediated Cell Cycle

Human periodontal ligament stem cells (PDLSCs), a type of mesenchymal stem cell, are a promising source for dental regeneration and are identified in human periodontal ligaments from extracted third molars. Valproic acid (VPA) is a histone deacetylase inhibitor that has been used as a wide-spectrum antiepileptic drug and a medication for mood disorders. VPA has shown several effects on increasing the pluripotency of embryonic stem cells and controlling osteogenic differentiation, besides the prevention of seizures. However, its effect on proliferation and osteogenesis depends on the cell type and concentration. The aim of this study was to investigate the effects of cyclic and constant VPA treatment on PDLSCs. Proliferation and apoptosis of PDLSCs were determined with cyclic and constant VPA treatment. In cemento/osteogenic differentiation, osteogenic markers decreased significantly after cyclic treatment with 0.5 mM VPA. In contrast, VPA enhanced osteogenic differentiation after constant treatment. With cyclic VPA treatment, p53 levels related to apoptotic pathway decreased to induce proliferation. These findings indicated that VPA has different roles in proliferation and differentiation of PDLSCs in vitro and in vivo via p53-related pathway.

The therapeutic contribution of nanomedicine to treat neurodegenerative diseases via neural stem cell differentiation

The discovery of adult neurogenesis drastically changed the therapeutic approaches of central nervous system regenerative medicine. The stimulation of this physiologic process can increase memory and motor performances in patients affected by neurodegenerative diseases. Neural stem cells contribute to the neurogenesis process through their differentiation into specialized neuronal cells. In this review, we describe the most important methods developed to restore neurological functions via neural stem cell differentiation. In particular, we focused on the role of nanomedicine. The application of nanostructured scaffolds, nanoparticulate drug delivery systems, and nanotechnology-based real-time imaging has significantly improved the safety and the efficacy of neural stem cell-based treatments. This review provides a comprehensive background on the contribution of nanomedicine to the modulation of neurogenesis via neural stem cell differentiation.

Valproic acid reduces hair loss and improves survival in patients receiving temozolomide-based radiation therapy for high-grade glioma

PURPOSE

Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, is also used to manage seizures in glioblastoma patients. HDAC inhibitors can protect normal cells and tissues from the deleterious effects of radiotherapy, and VPA is reported to improve the survival of glioblastoma patients receiving chemoradiation therapy. VPA also promotes hair growth, and thus has the potential to reduce the radiotherapy side effect of hair loss while improving the survival of patients with glioblastoma. The purpose of this study was to determine whether VPA use during radiotherapy for high-grade glioma is associated with decreased side effects of radiotherapy and an improvement in overall survival (OS) and progression-free survival (PFS).

METHODS

Medical records of 112 patients with high-grade glioma were retrospectively reviewed. We grouped patients by VPA use or non-use during radiotherapy, and evaluated hair loss, OS, and PFS.

RESULTS

The radiation dose and fractionation at the onset of hair loss were 4 Gy and two fractions higher, respectively, in the VPA group compared with the VPA non-use group (P < 0.01). Median OS was 42.2 and 20.3 months in the VPA use and non-use groups, respectively (P < 0.01; hazard ratio [HR], 0.36; 95% confidence interval [CI], 0.18-0.74). Median PFS was 22.7 and 11.0 months in the VPA use and non-use groups, respectively (P = 0.099; HR, 0.62; 95% CI, 0.36-1.09).

CONCLUSIONS

VPA use during radiotherapy for glioma is associated with delayed hair loss and improvement in survival. Hair loss prevention benefits patients suffering from the deleterious effects of radiation.

RhoA inhibits neural differentiation in murine stem cells through multiple mechanisms

Spontaneous neural differentiation of embryonic stem cells is induced by Noggin-mediated inhibition of bone morphogenetic protein 4 (BMP4) signaling. RhoA is a guanosine triphosphatase (GTPase) that regulates cytoskeletal dynamics and gene expression, both of which control stem cell fate. We found that disruption of Syx, a gene encoding a RhoA-specific guanine nucleotide exchange factor, accelerated retinoic acid-induced neural differentiation in murine embryonic stem cells aggregated into embryoid bodies. Cells from Syx(+/+) and Syx(-/-) embryoid bodies had different abundances of proteins implicated in stem cell pluripotency. The differentiation-promoting proteins Noggin and RARγ (a retinoic acid receptor) were more abundant in cells of Syx(-/-) embryoid bodies, whereas the differentiation-suppressing proteins SIRT1 (a protein deacetylase) and the phosphorylated form of SMAD1 (the active form of this transcription factor) were more abundant in cells of Syx(+/+) embryoid bodies. These differences were blocked by the overexpression of constitutively active RhoA, indicating that the abundance of these proteins was maintained, at least in part, by RhoA activity. The peripheral stress fibers in cells from Syx(-/-) embryoid bodies were thinner than those in Syx(+/+) cells. Furthermore, less Noggin and fewer vesicles containing Rab3d, a GTPase that mediates Noggin trafficking, were detected in cells from Syx(-/-) embryoid bodies, which could result from increased Noggin exocytosis. These results suggested that, in addition to inhibiting Noggin transcription, RhoA activity in wild-type murine embryonic stem cells also prevented neural differentiation by limiting Noggin secretion.

Retinoic-acid-mediated HRas stabilization induces neuronal differentiation of neural stem cells during brain development

Ras signaling is tightly regulated during neural stem cell (NSC) differentiation, and defects in this pathway result in aberrant brain development. However, the mechanism regulating Ras signaling during NSC differentiation was unknown. Here, we show that stabilized HRas specifically induces neuronal differentiation of NSCs. Lentivirus-mediated HRas overexpression and knockdown resulted in stimulation and inhibition, respectively, of NSC differentiation into neuron in the ex vivo embryo. Retinoic acid, an active metabolite of vitamin A, promoted neuronal differentiation of NSCs by stabilizing HRas, and HRas knockdown blocked the retinoic acid effect. Vitamin-A-deficient mice displayed abnormal brain development with reduced HRas levels and a reduced thickness of the postmitotic region containing differentiated neurons. All of these abnormal phenotypes were rescued with the restoration of HRas protein levels achieved upon feeding with a retinoic-acid-supplemented diet. In summary, this study shows that retinoic acid stabilizes HRas protein during neurogenesis, and that this is required for NSC differentiation into neurons and murine brain development.

Clinical and Neurobiological Relevance of Current Animal Models of Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social and communication impairments, as well as repetitive and restrictive behaviors. The phenotypic heterogeneity of ASD has made it overwhelmingly difficult to determine the exact etiology and pathophysiology underlying the core symptoms, which are often accompanied by comorbidities such as hyperactivity, seizures, and sensorimotor abnormalities. To our benefit, the advent of animal models has allowed us to assess and test diverse risk factors of ASD, both genetic and environmental, and measure their contribution to the manifestation of autistic symptoms. At a broader scale, rodent models have helped consolidate molecular pathways and unify the neurophysiological mechanisms underlying each one of the various etiologies. This approach will potentially enable the stratification of ASD into clinical, molecular, and neurophenotypic subgroups, further proving their translational utility. It is henceforth paramount to establish a common ground of mechanistic theories from complementing results in preclinical research. In this review, we cluster the ASD animal models into lesion and genetic models and further classify them based on the corresponding environmental, epigenetic and genetic factors. Finally, we summarize the symptoms and neuropathological highlights for each model and make critical comparisons that elucidate their clinical and neurobiological relevance.

Reduced Adult Hippocampal Neurogenesis and Cognitive Impairments following Prenatal Treatment of the Antiepileptic Drug Valproic Acid

Prenatal exposure to valproic acid (VPA), an established antiepileptic drug, has been reported to impair postnatal cognitive function in children born to VPA-treated epileptic mothers. However, how these defects arise and how they can be overcome remain unknown. Using mice, we found that comparable postnatal cognitive functional impairment is very likely correlated to the untimely enhancement of embryonic neurogenesis, which led to depletion of the neural precursor cell pool and consequently a decreased level of adult neurogenesis in the hippocampus. Moreover, hippocampal neurons in the offspring of VPA-treated mice showed abnormal morphology and activity. Surprisingly, these impairments could be ameliorated by voluntary running. Our study suggests that although prenatal exposure to antiepileptic drugs such as VPA may have detrimental effects that persist until adulthood, these effects may be offset by a simple physical activity such as running.

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Prenatal VPA treatment caused an untimely enhancement of embryonic neurogenesis

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Prenatal VPA treatment has the long-term effect of impairing adult neurogenesis

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Reduced level of adult neurogenesis is associated with cognitive functional impairments

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Voluntary running can ameliorate the persistent detrimental effects caused by VPA

Differentiation of rat adipose tissue-derived stem cells into neuron-like cells by valproic acid, a histone deacetylase inhibitor

Valproic acid (VPA) is a widely used antiepileptic drug, which has recently been reported to modulate the neuronal differentiation of adipose tissue-derived stem cells (ASCs) in humans and dogs. However, controversy exists as to whether VPA really acts as an inducer of neuronal differentiation of ASCs. The present study aimed to elucidate the effect of VPA in neuronal differentiation of rat ASCs. One or three days of pretreatment with VPA (2 mM) followed by neuronal induction enhanced the ratio of immature neuron marker βIII-tubulin-positive cells in a time-dependent manner, where the majority of cells also had a positive signal for neurofilament medium polypeptide (NEFM), a mature neuron marker. RT-PCR analysis revealed increases in the mRNA expression of microtubule-associated protein 2 (MAP2) and NEFM mature neuron markers, even without neuronal induction. Three-days pretreatment of VPA increased acetylation of histone H3 of ASCs as revealed by immunofluorescence staining. Chromatin immunoprecipitation assay also showed that the status of histone acetylation at H3K9 correlated with the gene expression of TUBB3 in ASCs by VPA. These results indicate that VPA significantly promotes the differentiation of rat ASCs into neuron-like cells through acetylation of histone H3, which suggests that VPA may serve as a useful tool for producing transplantable cells for future applications in clinical treatments.

Amniotic fluid exerts a neurotrophic influence on fetal neurodevelopment via the ERK/GSK-3 pathway

BACKGROUND

The fetus is surrounded by the amniotic fluid (AF) contained by the amniotic sac of the pregnant female. The AF is directly conveyed to the fetus during pregnancy. Although AF has recently been reported as an untapped resource containing various substances, it remains unclear whether the AF could influence fetal neurodevelopment.

RESULTS

We used AF that was extracted from embryos at 16 days in pregnant SD rat and exposed the AF to the neural cells derived from the embryos of same rat. We found that the treatment of AF to cortical neurons increased the phosphorylation in ERK1/2 that is necessary for fetal neurodevelopment, which was inhibited by the treatment of MEK inhibitors. Moreover, we found the subsequent inhibition of glycogen synthase kinase-3 (GSK-3), which is an important determinant of cell fate in neural cells. Indeed, AF increased the neural clustering of cortical neurons, which revealed that the clustered cells were proliferating neural progenitor cells. Accordingly, we confirmed the ability of AF to increase the neural progenitor cells through neurosphere formation. Furthermore, we showed that the ERK/GSK-3 pathway was involved in AF-mediated neurosphere enlargement.

CONCLUSIONS

Although the placenta mainly supplies oxygenated blood, nutrient substances for fetal development, these findings further suggest that circulating-AF into the fetus could affect fetal neurodevelopment via MAP kinases-derived GSK-3 pathway during pregnancy. Moreover, we suggest that AF could be utilized as a valuable resource in the field of regenerative medicine.

Kuwanon V inhibits proliferation, promotes cell survival and increases neurogenesis of neural stem cells

Neural stem cells (NSCs) have the ability to proliferate and differentiate into neurons and glia. Regulation of NSC fate by small molecules is important for the generation of a certain type of cell. The identification of small molecules that can induce new neurons from NSCs could facilitate regenerative medicine and drug development for neurodegenerative diseases. In this study, we screened natural compounds to identify molecules that are effective on NSC cell fate determination. We found that Kuwanon V (KWV), which was isolated from the mulberry tree (Morus bombycis) root, increased neurogenesis in rat NSCs. In addition, during NSC differentiation, KWV increased cell survival and inhibited cell proliferation as shown by 5-bromo-2-deoxyuridine pulse experiments, Ki67 immunostaining and neurosphere forming assays. Interestingly, KWV enhanced neuronal differentiation and decreased NSC proliferation even in the presence of mitogens such as epidermal growth factor and fibroblast growth factor 2. KWV treatment of NSCs reduced the phosphorylation of extracellular signal-regulated kinase 1/2, increased mRNA expression levels of the cyclin-dependent kinase inhibitor p21, down-regulated Notch/Hairy expression levels and up-regulated microRNA miR-9, miR-29a and miR-181a. Taken together, our data suggest that KWV modulates NSC fate to induce neurogenesis, and it may be considered as a new drug candidate that can regenerate or protect neurons in neurodegenerative diseases.

Shoc2/Sur8 protein regulates neurite outgrowth

The Shoc2 protein has been implicated in the positive regulation of the Ras-ERK pathway by increasing the functional binding interaction between Ras and Raf, leading to increased ERK activity. Here we found that Shoc2 overexpression induced sustained ERK phosphorylation, notably in the case of EGF stimulation, and Shoc2 knockdown inhibited ERK activation. We demonstrate that ectopic overexpression of human Shoc2 in PC12 cells significantly promotes neurite extension in the presence of EGF, a stimulus that induces proliferation rather than differentiation in these cells. Finally, Shoc2 depletion reduces both NGF-induced neurite outgrowth and ERK activation in PC12 cells. Our data indicate that Shoc2 is essential to modulate the Ras-ERK signaling outcome in cell differentiation processes involved in neurite outgrowth.