Dysregulation of the Wnt/ß-catenin signaling pathway via Rnf146 upregulation in a VPA-induced mouse model of autism spectrum disorder.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder associated with impaired social behavior and communication, repetitive behaviors, and restricted interests. In addition to genetic factors, environmental factors such as prenatal drug exposure contribute to the development of ASD. However, how those prenatal factors induce behavioral deficits in the adult stage is not clear. To elucidate ASD pathogenesis at the molecular level, we performed a high-resolution mass spectrometry-based quantitative proteomic analysis on the prefrontal cortex (PFC) of mice exposed to valproic acid (VPA) in utero, a widely used animal model of ASD. Differentially expressed proteins (DEPs) in VPA-exposed mice showed significant overlap with ASD risk genes, including differentially expressed genes from the postmortem cortex of ASD patients. Functional annotations of the DEPs revealed significant enrichment in the Wnt/ß-catenin signaling pathway, which is dysregulated by the upregulation of Rnf146 in VPA-exposed mice. Consistently, overexpressing Rnf146 in the PFC impaired social behaviors and altered the Wnt signaling pathway in adult mice. Furthermore, Rnf146-overexpressing PFC neurons showed increased excitatory synaptic transmission, which may underlie impaired social behavior. These results demonstrate that Rnf146 is critical for social behavior and that dysregulation of Rnf146 underlies social deficits in VPA-exposed mice.

Ethyl pyruvate prevents long-term stress-induced cognitive decline and modulates Akt/GSK-3ß signaling.

Stress is an inevitable part of life and, simultaneously, a stimulus that can trigger various neuropsychiatric disorders. Therefore, proper stress management is essential for maintaining a healthy life. In this study, we investigated the suppression of stress-induced cognitive deficit by controlling changes in synaptic plasticity caused by stress and confirmed that ethyl pyruvate (EP) has such an effect. Corticosterone, a stress hormone, suppresses long-term potentiation (LTP) in mouse acute hippocampal slices. EP blocked the LTP inhibitory effect of corticosterone by regulating GSK-3ß function. Restraint stress for 2 weeks increased the anxiety levels and caused the cognitive decline in the experimental animals. Administration of EP for 14 days did not affect the increase in anxiety caused by stress but improved cognitive decline caused by stress. In addition, the decrease in neurogenesis and synaptic function deficits in the hippocampus, which cause of cognitive decline due to stress, were improved by EP administration. These effects appear via regulation of Akt/GSK-3ß signaling, as in in vitro studies. These results suggest that EP prevents stress-induced cognitive decline through the modulation of Akt/GSK-3ß-mediated synaptic regulation.

Correlation between immune-related genes and depression-like features in an animal model and in humans.

A growing body of evidence suggests that immune-related genes play pivotal roles in the pathophysiology of depression. In the present study, we investigated a plausible connection between gene expression, DNA methylation, and brain structural changes in the pathophysiology of depression using a combined approach of murine and human studies. We ranked the immobility behaviors of 30 outbred Crl:CD1 (ICR) mice in the forced swim test (FST) and harvested their prefrontal cortices for RNA sequencing. Of the 24,532 analyzed genes, 141 showed significant correlations with FST immobility time, as determined through linear regression analysis with p ≤ 0.01. The identified genes were mostly involved in immune responses, especially interferon signaling pathways. Moreover, induction of virus-like neuroinflammation in the brains of two separate mouse cohorts (n = 30 each) using intracerebroventricular polyinosinic:polycytidylic acid injection resulted in increased immobility during FST and similar expression of top immobility-correlated genes. In human blood samples, candidate gene (top 5%) expression profiling using DNA methylation analysis found the interferon-related USP18 (cg25484698, p = 7.04 × 10-11, Δß = 1.57 × 10-2; cg02518889, p = 2.92 × 10-3, Δß =  - 8.20 × 10-3) and IFI44 (cg07107453, p = 3.76 × 10-3, Δß =  - 4.94 × 10-3) genes to be differentially methylated between patients with major depressive disorder (n = 350) and healthy controls (n = 161). Furthermore, cortical thickness analyses using T1-weighted images revealed that the DNA methylation scores for USP18 were negatively correlated with the thicknesses of several cortical regions, including the prefrontal cortex. Our results reveal the important role of the interferon pathway in depression and suggest USP18 as a potential candidate target. The results of the correlation analysis between transcriptomic data and animal behavior carried out in this study provide insights that could enhance our understanding of depression in humans.

Caspase Cleavage of Receptor Tyrosine Kinases in the Dependence Receptor Family.

Dependence receptors are a group of receptor proteins with shared characteristics of transducing two different signals within cells. They can transduce a positive signal of survival and differentiation in the presence of ligands. On the other hand, dependence receptors can transduce an apoptosis signal in the absence of ligands. The function of these receptors depends on the availability of their ligands. Several receptor tyrosine kinases (RTKs) have been reported as dependence receptors. When cells undergo apoptosis by dependence receptors, the intracellular domain of some RTKs is cleaved by the caspases. Among the RTKs that belong to dependence receptors, we focused on eight RTKs (RET, HER2, MET, ALK, TrkC, EphA4, EphB3, and c-KIT) that are cleaved by caspases. In this review, we describe the features of the receptors, their cleavage sites, and the fate of the cleaved products, as well as recent implications on them being used as potential therapeutics for cancer treatment.

Phyllodulcin improves hippocampal long-term potentiation in 5XFAD mice.

Alzheimer's disease (AD) is a well-known neurodegenerative brain disease, and no curative treatment has yet been developed. The main symptoms include various brain lesions, caused by amyloid ß (Aß) aggregation, and cognitive decline. Therefore, it is believed that substances that control Aß will inhibit the onset of Alzheimer's disease and slow its progression. In this study, the effect of phyllodulcin, a major component of hydrangea, on Aß aggregation and brain pathology in an animal model of AD was studied. Phyllodulcin inhibited the aggregation of Aß and decomposed the pre-aggregated Aß in a concentration-dependent manner. In addition, it inhibited the cytotoxicity of Aß aggregates. Oral administration of phyllodulcin improved Aß-induced memory impairments in normal mice, reduced Aß deposition in the hippocampus, inhibited the activation of microglia and astrocytes, and improved synaptic plasticity in 5XFAD mice. These results suggest that phyllodulcin may be a candidate for the treatment of AD.

Investigation of Phospholipid Differences in Valproic Acid-Induced Autistic Mouse Model Brain Using Mass Spectrometry Imaging.

Autism is a neurodevelopmental disorder for which the cause and treatment have yet not been determined. The polyunsaturated fatty acid (PUFA) levels change rapidly in the blood or cerebrospinal fluid of autistic children and PUFAs are closely related to autism spectrum disorder (ASD). This finding suggests that changes in lipid metabolism are associated with ASD and result in an altered distribution of phospholipids in cell membranes. To further understand ASD, it is necessary to analyze phospholipids in organs consisting of nerve cells, such as the brain. In this study, we investigated the phospholipid distribution in the brain tissue of valproic acid-induced autistic mice using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Phospholipids including phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine were identified in each brain region and exhibited differences between the ASD and control groups. These phospholipids contain docosahexaenoic acid and arachidonic acid, which are important PUFAs for cell signaling and brain growth. We expect that the differences in phospholipids identified in the brain tissue of the ASD model with MALDI-MSI, in conjunction with conventional biological fluid analysis, will help to better understand changes in lipid metabolism in ASD.

Augmented impulsive behavior in febrile seizure-induced mice.

Febrile seizure (FS) is one of the most prevalent etiological events in childhood affecting 2-5% of children from 3 months to 5 years old. Debates on whether neurodevelopmental consequences rise in later life following a febrile seizure or not are still ongoing however there is limited evidence of its effect, especially in a laboratory setting. Moreover, the comparative study using both male and female animal models is sparse. To examine the effect of FS on the behavioral features of mice, both sexes of ICR mice were induced with hyperthermic seizures through exposure to an infrared heat lamp. The mice were divided into two groups, one receiving a single febrile seizure at postnatal day 11 (P11) and one receiving three FS at P11, P13, and P15. Starting at P30 the FS-induced mice were subjected to a series of behavioral tests. Mice with seizures showed no locomotor and motor coordination deficits, repetitive, and depressive-like behavior. However, the FS-induced mice showed impulsive-like behavior in both elevated plus maze and cliff avoidance tests, which is more prominent in male mice. A greater number of mice displayed impaired CAT in both males and females in the three-time FS-induced group compared to the single induction group. These results demonstrate that after induction of FS, male mice have a higher susceptibility to consequences of febrile seizure than female mice and recurrent febrile seizure has a higher chance of subsequent disorders associated with decreased anxiety and increased impulsivity. We confirmed the dysregulated expression of impulsivity-related genes such as 5-HT1A and tryptophan hydroxylase 2 from the prefrontal cortices of FS-induced mice implying that the 5-HT system would be one of the mechanisms underlying the increased impulsivity after FS. Taken together, these findings are useful in unveiling future discoveries about the effect of childhood febrile seizure and the mechanism behind it.

Minoxidil Regulates Aging-Like Phenotypes in Rat Cortical Astrocytes In Vitro.

Mainly due to the slanted focus on the mechanism and regulation of neuronal aging, research on astrocyte aging and its modulation during brain aging is scarce. In this study, we established aged astrocyte culture model by long-term culturing. Cellular senescence was confirmed through SA-ß-gal staining as well as through the examination of morphological, molecular, and functional markers. RNA sequencing and functional analysis of astrocytes were performed to further investigate the detailed characteristics of the aged astrocyte model. Along with aged phenotypes, decreased astrocytic proliferation, migration, mitochondrial energetic function and support for neuronal survival and differentiation has been observed in aged astrocytes. In addition, increased expression of cytokines and chemokine-related factors including plasminogen activator inhibitor -1 (PAI-1) was observed in aged astrocytes. Using the RNA sequencing results, we searched potential drugs that can normalize the dysregulated gene expression pattern observed in long-term cultured aged astrocytes. Among several candidates, minoxidil, a pyrimidine-derived anti-hypertensive and anti-pattern hair loss drug, normalized the increased number of SA-ß-gal positive cells and nuclear size in aged astrocytes. In addition, minoxidil restored up-regulated activity of PAI-1 and increased mitochondrial superoxide production in aged astrocytes. We concluded that long term culture of astrocytes can be used as a reliable model for the study of astrocyte senescence and minoxidil can be a plausible candidate for the regulation of brain aging.

Cntnap2-dependent molecular networks in autism spectrum disorder revealed through an integrative multi-omics analysis.

Autism spectrum disorder (ASD) is a major neurodevelopmental disorder in which patients present with core symptoms of social communication impairment, restricted interest, and repetitive behaviors. Although various studies have been performed to identify ASD-related mechanisms, ASD pathology is still poorly understood. CNTNAP2 genetic variants have been found that represent ASD genetic risk factors, and disruption of Cntnap2 expression has been associated with ASD phenotypes in mice. In this study, we performed an integrative multi-omics analysis by combining quantitative proteometabolomic data obtained with Cntnap2 knockout (KO) mice with multi-omics data obtained from ASD patients and forebrain organoids to elucidate Cntnap2-dependent molecular networks in ASD. To this end, a mass spectrometry-based proteometabolomic analysis of the medial prefrontal cortex in Cntnap2 KO mice led to the identification of Cntnap2-associated molecular features, and these features were assessed in combination with multi-omics data obtained on the prefrontal cortex in ASD patients to identify bona fide ASD cellular processes. Furthermore, a reanalysis of single-cell RNA sequencing data obtained from forebrain organoids derived from patients with CNTNAP2-associated ASD revealed that the aforementioned identified ASD processes were mainly linked to excitatory neurons. On the basis of these data, we constructed Cntnap2-associated ASD network models showing mitochondrial dysfunction, axonal impairment, and synaptic activity. Our results may shed light on the Cntnap2-dependent molecular networks in ASD.

Hycanthone Inhibits Inflammasome Activation and Neuroinflammation-Induced Depression-Like Behaviors in Mice.

Despite the various medications used in clinics, the efforts to develop more effective treatments for depression continue to increase in the past decades mainly because of the treatment-resistant population, and the testing of several hypotheses- and target-based treatments. Undesirable side effects and unresponsiveness to current medications fuel the drive to solve this top global health problem. In this study, we focused on neuroinflammatory response-mediated depression which represents a cluster of depression etiology both in animal models and humans. Several meta-analyses reported that proinflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) were increased in major depressive disorder patients. Inflammatory mediators implicated in depression include type-I interferon and inflammasome pathways. To elucidate the molecular mechanisms of neuroinflammatory cascades underlying the pathophysiology of depression, we introduced hycanthone, an antischistosomal drug, to check whether it can counteract depressive-like behaviors in vivo and normalize the inflammation-induced changes in vitro. Lipopolysaccharide (LPS) treatment increased proinflammatory cytokine expression in the murine microglial cells as well as the stimulation of type I interferon-related pathways that are directly or indirectly regulated by Janus kinase-signal transducer and activator of transcription (JAK-STAT) activation. Hycanthone treatment attenuated those changes possibly by inhibiting the JAK-STAT pathway and inflammasome activation. Hycanthone also ameliorated depressive-like behaviors by LPS. Taken together, we suggest that the inhibitory action of hycanthone against the interferon pathway leading to attenuation of depressive-like behaviors can be a novel therapeutic mechanism for treating depression.

The effect of lansoprazole on MK-801-induced schizophrenia-like behaviors in mice.

As a heterogeneous disorder, schizophrenia is known to be associated with neuroinflammation. A recent study showed that several cytokines are higher in the plasma and cerebrospinal fluid of schizophrenia patients. Lansoprazole, a proton pump inhibitor used for treating erosive esophagitis, has been reported to reduce INF-γ-induced neurotoxicity and decrease inflammatory cytokines including IL-1ß, IL-6, and TNF-α. These findings persuaded us to examine whether lansoprazole ameliorates schizophrenia-like symptoms. The schizophrenia mouse model was induced by the acute administration of MK-801, an NMDA receptor antagonist. Sensorimotor gating, Barnes maze, and social novelty preference tests were conducted to evaluate schizophrenia-like behaviors. We found that lansoprazole (0.3, 1, or 3 mg/kg) ameliorated sensorimotor gating deficits, spatial learning, and social deficits caused by MK-801 treatment (0.2 mg/kg). The catalepsy test, balance beam test, and rotarod test were performed to reveal the adverse effects of lansoprazole on motor coordination. The behavioral results indicated that lansoprazole did not result in any motor function deficits. Moreover, lansoprazole decreased inflammatory cytokines including IL-6 and TNF-α only in the cortex, but not in the hippocampus. Collectively, these results suggest that lansoprazole could be a potential candidate for treating schizophrenia patients who suffer from sensorimotor gating deficits or social disability without any motor-related adverse effects.

Pirenperone relieves the symptoms of fragile X syndrome in Fmr1 knockout mice.

Fragile X syndrome (FXS) is a neurodevelopmental disorder that is caused by the loss of Fragile X-linked mental retardation protein (FMRP), an RNA binding protein that can bind and recognize different RNA structures and regulate the target mRNAs' translation involved in neuronal synaptic plasticity. Perturbations of this gene expression network have been related to abnormal behavioral symptoms such as hyperactivity, and impulsivity. Considering the roles of FMRP in the modulation of mRNA translation, we investigated the differentially expressed genes which might be targeted to revert to normal and ameliorate behavioral symptoms. Gene expression data was analyzed and used the connectivity map (CMap) to understand the changes in gene expression in FXS and predict the effective drug candidates. We analyzed the GSE7329 dataset that had 15 control and 8 FXS patients' lymphoblastoid samples. Among 924 genes, 42 genes were selected as signatures for CMap analysis, and 24 associated drugs were found. Pirenperone was selected as a potential drug candidate for FXS for its possible antipsychotic effect. Treatment of pirenperone increased the expression level of Fmr1 gene. Moreover, pirenperone rescued the behavioral deficits in Fmr1 KO mice including hyperactivity, spatial memory, and impulsivity. These results suggest that pirenperone is a new drug candidate for FXS, which should be verified in future studies.

Novel Therapeutics for Treating Sleep Disorders: New Perspectives on Maydis stigma.

Sleep is a restorative period that plays a crucial role in the physiological functioning of the body, including that of the immune system, memory processing, and cognition. Sleep disturbances can be caused by various physical, mental, and social problems. Recently, there has been growing interest in sleep. Maydis stigma (MS, corn silk) is a female maize flower that is traditionally used as a medicinal plant to treat many diseases, including hypertension, edema, and diabetes. It is also used as a functional food in tea and other supplements. ß-Sitosterol (BS) is a phytosterol and a natural micronutrient in higher plants, and it has a similar structure to cholesterol. It is a major component of MS and has anti-inflammatory, antidepressive, and sedative effects. However, the potential effects of MS on sleep regulation remain unclear. Here, we investigated the effects of MS on sleep in mice. The effects of MS on sleep induction were determined using pentobarbital-induced sleep and caffeine-induced sleep disruption mouse models. MS extracts decreased sleep latency and increased sleep duration in both the pentobarbital-induced sleep induction and caffeine-induced sleep disruption models compared to the positive control, valerian root extract. The butanol fraction of MS extracts decreased sleep latency time and increased sleep duration. In addition, ß-sitosterol enhances sleep latency and sleep duration. Both MS extract and ß-sitosterol increased alpha activity in the EEG analysis. We measured the mRNA expression of melatonin receptors 1 and 2 (MT1/2) using qRT-PCR. The mRNA expression of melatonin receptors 1 and 2 was increased by MS extract and ß-sitosterol treatment in rat primary cultured neurons and the brain. In addition, MS extract increased the expression of clock genes including per1/2, cry1/2, and Bmal1 in the brain. MS extract and ß-sitosterol increased the phosphorylation of ERK1/2 and αCaMKII. Our results demonstrate for the first time that MS has a sleep-promoting effect via melatonin receptor expression, which may provide new scientific evidence for its use as a potential therapeutic agent for the treatment and prevention of sleep disturbance.

Agmatine relieves behavioral impairments in Fragile X mice model.

BACKGROUND: Fragile X syndrome (FXS) is the most common heritable form of neurodevelopmental disorder, which is caused by the loss of fragile X mental retardation protein (FMRP) expression. Despite the unceasing efforts to develop therapeutic agents against FXS based on the pathophysiological changes observed in animal models of FXS and human patients, therapeutic candidates including mGluR signaling modulators have failed to provide sufficient effects. Based on the recent successful demonstration of an endogenous polyamine, agmatine, to improve the autism-like symptoms in the valproic acid animal model of autism, we investigated the effects of agmatine against FXS symptoms using Fmr1 knockout (KO) mice. METHODS: We used male Fmr1 KO mice for behavioral tests such as marble burying, open-field test, memory tasks, social interaction tests and startle response to confirm the symptoms of FXS. We also checked the electrophysiological profile of neural activity in agmatine-treated Fmr1 KO mice. RESULTS: Agmatine reversed the compulsion, learning and memory deficits, hyperactivity, aberrant social interaction, and communication deficit in Fmr1 KO mice while it normalized the aberrant LTP and LTD in the hippocampus. CONCLUSIONS: The results highlight the potential of agmatine's novel disease-ameliorating effects in FXS, which warrants further studies to ascertain whether these findings translate into clinical effects in FXS patients.

Hyperoside improves learning and memory deficits by amyloid ß1-42 in mice through regulating synaptic calcium-permeable AMPA receptors.

Alzheimer's disease (AD) is the most common degenerative disease and is indicative of dementia. The cerebral accumulation of amyloid ß (Aß), a crucial factor in AD, initiates synaptic and cognitive dysfunction. Therefore, the elevation of synaptic and cognitive functions may help manage dementia in AD. In this study, we suggest hyperoside as a synaptic function- and memory-enhancing agent. Hyperoside enhanced learning and memory in passive avoidance and object recognition tasks. Hyperoside facilitated synaptic long-term potentiation (LTP) in acute hippocampal slices. IEM-1460, a calcium-permeable amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (CP-AMPAR) antagonist, blocked the facilitation effect of hyperoside. Hyperoside also induced N-methyl-d-aspartate receptor (NMDAR)-independent LTP, which was blocked by IEM-1460, suggesting the involvement of CP-AMPARs in the synaptic effects of hyperoside-mediated LTP. PKI (a PKA inhibitor) or SQ22536 (adenylyl cyclase, an AC inhibitor) blocked hyperoside-facilitated LTP and hyperoside-induced NMDAR-independent LTP. Hyperoside-enhanced learning and memory were blocked by IEM-1460, suggesting the involvement of CP-AMPARs in the effect of hyperoside on learning and memory. Finally, hyperoside ameliorated Aß-induced memory impairments in an AD mouse model. These results suggest that hyperoside enhances learning and memory, and this may be due to the effect of CP-AMPARs.

Eugenitol ameliorates memory impairments in 5XFAD mice by reducing Aß plaques and neuroinflammation.

Alzheimer's disease (AD) is caused by various pathological mechanisms; therefore, it is necessary to develop drugs that simultaneously act on multiple targets. In this study, we investigated the effects of eugenitol, which has anti-amyloid ß (Aß) and anti-neuroinflammatory effects, in an AD mouse model. We found that eugenitol potently inhibited Aß plaque and oligomer formation. Moreover, eugenitol dissociated the preformed Aß plaques and reduced Aß-induced nero2a cell death. An in silico docking simulation study showed that eugenitol may interact with Aß1-42 monomers and fibrils. Eugenitol showed radical scavenging effects and potently reduced the release of proinflammatory cytokines from lipopolysaccharide-treated BV2 cells. Systemic administration of eugenitol blocked Aß aggregate-induced memory impairment in the Morris water maze test in a dose-dependent manner. In 5XFAD mice, prolonged administration of eugenitol ameliorated memory and hippocampal long-term potentiation impairment. Moreover, eugenitol significantly reduced Aß deposits and neuroinflammation in the hippocampus of 5XFAD mice. These results suggest that eugenitol, which has anti-Aß aggregation, Aß fibril dissociation, and anti-inflammatory effects, potently modulates AD-like pathologies in 5XFAD mice, and could be a promising candidate for AD therapy.

Decreased in vivo glutamate/GABA ratio correlates with the social behavior deficit in a mouse model of autism spectrum disorder.

To diagnose autism spectrum disorder (ASD), researchers have sought biomarkers whose alterations correlate with the susceptibility to ASD. However, biomarkers closely related to the pathophysiology of ASD are lacking. Even though excitation/inhibition (E/I) imbalance has been suggested as an underlying mechanism of ASD, few studies have investigated the actual ratio of glutamate (Glu) to γ-aminobutyric acid (GABA) concentration in vivo. Moreover, there are controversies in the directions of E/I ratio alterations even in extensively studied ASD animal models. Here, using proton magnetic resonance spectroscopy (1H-MRS) at 9.4T, we found significant differences in the levels of different metabolites or their ratios in the prefrontal cortex and hippocampus of Cntnap2-/- mice compared to their wild-type littermates. The Glu/GABA ratio, N-acetylaspartate (NAA)/total creatine (tCr) ratio, and tCr level in the prefrontal cortex were significantly different in Cntnap2-/- mice compared to those in wild-type mice, and they significantly correlated with the sociability of mice. Moreover, receiver operating characteristic (ROC) analyses indicated high specificity and selectivity of these metabolites in discriminating genotypes. These results suggest that the lowered Glu/GABA ratio in the prefrontal cortex along with the changes in the other metabolites might contribute to the social behavior deficit in Cntnap2-/- mice. Our results also demonstrate the utility of 1H-MRS in investigating the underlying mechanisms or the diagnosis of ASD.

Behavioral Deficits in Adolescent Mice after Sub-Chronic Administration of NMDA during Early Stage of Postnatal Development.

Neurodevelopmental disorders are complex conditions that pose difficulty in the modulation of proper motor, sensory and cognitive function due to dysregulated neuronal development. Previous studies have reported that an imbalance in the excitation/ inhibition (E/I) in the brain regulated by glutamatergic and/or GABAergic neurotransmission can cause neurodevelopmental and neuropsychiatric behavioral deficits such as autism spectrum disorder (ASD). NMDA acts as an agonist at the NMDA receptor and imitates the action of the glutamate on that receptor. NMDA however, unlike glutamate, only binds to and regulates the NMDA receptor subtypes and not the other glutamate receptors. This study seeks to determine whether NMDA administration in mice i.e., over-activation of the NMDA system would result in long-lasting behavioral deficits in the adolescent mice. Both gender mice were treated with NMDA or saline at early postnatal developmental period with significant synaptogenesis and synaptic maturation. On postnatal day 28, various behavioral experiments were conducted to assess and identify behavioral characteristics. NMDA-treated mice show social deficits, and repetitive behavior in both gender mice at adolescent periods. However, only the male mice but not female mice showed increased locomotor activity. This study implies that neonatal exposure to NMDA may illicit behavioral features similar to ASD. This study also confirms the validity of the E/I imbalance theory of ASD and that NMDA injection can be used as a pharmacologic model for ASD. Future studies may explore the mechanism behind the gender difference in locomotor activity as well as the human relevance and therapeutic significance of the present findings.

Role of extracellular signal-regulated kinase in rubrofusarin-enhanced cognitive functions and neurite outgrowth.

Memory-enhancing agents have long been required for various reasons such as for obtaining a good score in a test in the young and for retaining memory in the aged. Although many studies have found that several natural products may be good candidates for memory enhancement, there is still a need for better agents. The present study investigated whether rubrofusarin, an active ingredient in Cassiae semen, enhances learning and memory in normal mice. Passive avoidance and Morris water maze tests were performed to determine the memory-enhancing ability of rubrofusarin. To investigate synaptic function, hippocampal long-term potentiation (LTP) was measured. Western blotting was performed to determine protein levels. To investigate neurite outgrowth, DCX immunohistochemistry and cell culture were utilised. Rubrofusarin (1, 3, 10, 30 mg/kg) enhanced memory in passive avoidance and Morris water maze tests. Moreover, rubrofusarin ameliorated scopolamine-induced memory impairment. In the rubrofusarin-treated group, high-frequency stimulation induced higher LTP in the hippocampal Schaffer-collateral pathway compared to the control group. The rubrofusarin-treated group showed a higher number of DCX-positive immature neurons with an increase in the length of dendrites compared to the control group in the hippocampal dentate gyrus region. In vitro experiments showed that rubrofusarin facilitated neurite outgrowth in neuro2a cells through extracellular signal-regulated kinase (ERK). Finally, we found that extracellular signal-regulated kinase (ERK) is required for rubrofusarin-induced enhancement of neurite outgrowth, learning and memory. These results demonstrate that rubrofusarin enhances learning and memory and neurite outgrowth, and these might need activation of ERK pathway.