Preventive effects of cristacarpin on experimentally induced uveitis by targeting NF-κB.

Cristacarpin is a novel prenylated pterocarpan that reportedly exhibits broad anti-cancer activity by enhancing endoplasmic reticulum stress. However, whether and how cristacarpin affects in-flammatory processes remain largely unknown. In the present study, the anti-inflammatory effect of cristacarpin on lipopolysaccharide (LPS)-induced inflammation was investigated using zebrafish embryos, RAW 264.7 macrophages, and mouse uveitis models. In the non-toxic concentration range (from 20 to 100 µM), cristacarpin suppressed pro-inflammatory mediators such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α, while stimulating anti-inflammatory mediators such as IL-4 and IL-10 in LPS-stimulated RAW 264.7 cells and uveitis mouse models. Cristacarpin decreased cell adhesion of macrophages through downregulation of the expression of Ninjurin1 and matrix metalloproteinases. Furthermore, cristacarpin reduced macrophage migration in zebrafish embryos in vivo. Cristacarpin also increased cytosolic levels of inhibitor of nuclear factor-κB and suppressed the nuclear translocation of nuclear factor κ-light-chain-enhancer of activated B cells. Collectively, our results suggest that cristacarpin is a potential therapeutic candidate for developing ocular anti-inflammatory drugs.

Neuronal-driven glioma growth requires Gαi1 and Gαi3.

Neuroligin-3 (NLGN3) is necessary and sufficient to promote glioma cell growth. The recruitment of Gαi1/3 to the ligand-activated receptor tyrosine kinases (RTKs) is essential for mediating oncogenic signaling. Methods: Various genetic strategies were utilized to examine the requirement of Gαi1/3 in NLGN3-driven glioma cell growth. Results: NLGN3-induced Akt-mTORC1 and Erk activation was inhibited by decreasing Gαi1/3 expression. In contrast ectopic Gαi1/3 overexpression enhanced NLGN3-induced signaling. In glioma cells, NLGN3-induced cell growth, proliferation and migration were attenuated by Gαi1/3 depletion with shRNA, but facilitated with Gαi1/3 overexpression. Significantly, Gαi1/3 silencing inhibited orthotopic growth of patient-derived glioma xenografts in mouse brain, whereas forced Gαi1/3-overexpression in primary glioma xenografts significantly enhanced growth. The growth of brain-metastatic human lung cancer cells in mouse brain was largely inhibited with Gαi1/3 silencing. It was however expedited with ectopic Gαi1/3 overexpression. In human glioma Gαi3 upregulation was detected, correlating with poor prognosis. Conclusion: Gαi1/3 mediation of NLGN3-induced signaling is essential for neuronal-driven glioma growth.

Neuroligin 2 regulates absence seizures and behavioral arrests through GABAergic transmission within the thalamocortical circuitry.

Epilepsy and autism spectrum disorders (ASD) are two distinct brain disorders but have a high rate of co-occurrence, suggesting shared pathogenic mechanisms. Neuroligins are cell adhesion molecules important in synaptic function and ASD, but their role in epilepsy remains unknown. In this study, we show that Neuroligin 2 (NLG2) knockout mice exhibit abnormal spike and wave discharges (SWDs) and behavioral arrests characteristic of absence seizures. The anti-absence seizure drug ethosuximide blocks SWDs and rescues behavioral arrests and social memory impairment in the knockout mice. Restoring GABAergic transmission either by optogenetic activation of the thalamic reticular nucleus (nRT) presynaptic terminals or postsynaptic NLG2 expression in the thalamic neurons reduces the SWDs and behavioral arrests in the knockout mice. These results indicate that NLG2-mediated GABAergic transmission at the nRT-thalamic circuit represents a common mechanism underlying both epileptic seizures and ASD.

Activation of the Oxytocin Receptor Modulates the Expression of Synaptic Adhesion Molecules in a Cell-Specific Manner.

Synaptic cell adhesion molecules, including neurexins and neuroligins, mediate the formation and maintenance of connections between neuronal cells. Although neurexins and neuroligins are known to interact with each other in a calcium-dependent manner and several neuropeptides have been shown to act through G protein-coupled receptors to increase intracellular calcium levels, no studies have examined the role of the neuropeptide oxytocin in association with adhesion molecules. Given that oxytocin receptors are located on presynaptic and postsynaptic membranes and that oxytocin exerts direct effects on neuronal excitability, it could be hypothesized that oxytocin affects the expression of cell surface adhesion molecules. In the present study, we show that incubation in the presence of oxytocin (1 µM, 48 h) exerted cell-specific effects on the levels of neurexin 2α, neurexin 2ß, and neuroligin 3. Oxytocin significantly increased the mRNA expression levels of neurexin 2α, neurexin 2ß, and neuroligin 3 in SH-SY5Y, U-87MG, and primary cerebellar cells. The effect of inhibiting oxytocin receptors on the expression of neurexin 2ß was more dramatic in U-87MG cells than in SH-SY5Y cells. Oxytocin did not exert effects in primary corticohippocampal cells. Additionally, we measured the expression of selected GTPases to determine whether they could mediate the effects of oxytocin. Oxytocin induced a decrease in the mRNA level of Rac1 in U-87MG and primary cerebellar cells and exerted a stimulatory effect on the expression of RhoB at the gene and protein level in SH-SY5Y cells. These results suggest that the regulation of neurexins and neuroligins involves the activation of oxytocin receptors. These effects are likely mediated by the stimulation of RhoB GTPase, at least in certain types of cells.

Sex-dependent influence of chronic mild stress (CMS) on voluntary alcohol consumption; study of neurobiological consequences.

Alcohol use disorder and depression are highly comorbid, and both conditions exhibit important sexual dimorphisms. Here, we aimed to investigate voluntary alcohol consumption after 6weeks of chronic mild stress (CMS) in Wistar rats - employed as an animal model of depression. Male and female rats were investigated, and changes in several molecular markers were analysed in frontal cortex (FCx) and hippocampal formation (HF). CMS induced depressive-like responses in the forced swimming test - increased immobility time - in male and female animals, without affecting anhedonia (sucrose preference test) nor motor activity (holeboard); body weight gain and food intake were diminished only among CMS males. Voluntary alcohol consumption was evaluated in a two-bottle choice paradigm (ethanol 20% versus tap water) for 4 consecutive days; females exhibited a higher preference for alcohol compared to male animals. In particular, alcohol consumption was significantly higher among CMS females compared to CMS male animals. Remarkably, similar changes in both male and female animals exposed to CMS were observed regarding the expression levels of NCAM-140KDa (decrease), GFAP and CB1R expression (increase) within the FCx as well as for HF PSD-95 levels (increase). However, contrasting effects in males and females were reported in relation to synaptophysin (SYN) protein levels within the FCx, HF CB1R expression (a decrease among male animals but an increase in females); while the opposite pattern was observed for NCAM-140KDa protein levels in the HF. A decrease in CB2R expression was only observed in the HF of CMS-females. The present study suggests that male and female animals might be differentially affected by CMS regarding later voluntary alcohol consumption. In this initial approach, cortical SYN, and NCAM-140KDa, CB1R and CB2R expression within the HF have arisen as potential candidates to explain such sex differences in behaviour. However, the depression-alcoholism relationship still deserves further investigation.

Proteomic Analysis of Unbounded Cellular Compartments: Synaptic Clefts.

Cellular compartments that cannot be biochemically isolated are challenging to characterize. Here we demonstrate the proteomic characterization of the synaptic clefts that exist at both excitatory and inhibitory synapses. Normal brain function relies on the careful balance of these opposing neural connections, and understanding how this balance is achieved relies on knowledge of their protein compositions. Using a spatially restricted enzymatic tagging strategy, we mapped the proteomes of two of the most common excitatory and inhibitory synaptic clefts in living neurons. These proteomes reveal dozens of synaptic candidates and assign numerous known synaptic proteins to a specific cleft type. The molecular differentiation of each cleft allowed us to identify Mdga2 as a potential specificity factor influencing Neuroligin-2's recruitment of presynaptic neurotransmitters at inhibitory synapses.

Astrocytes Assemble Thalamocortical Synapses by Bridging NRX1α and NL1 via Hevin.

Proper establishment of synapses is critical for constructing functional circuits. Interactions between presynaptic neurexins and postsynaptic neuroligins coordinate the formation of synaptic adhesions. An isoform code determines the direct interactions of neurexins and neuroligins across the synapse. However, whether extracellular linker proteins can expand such a code is unknown. Using a combination of in vitro and in vivo approaches, we found that hevin, an astrocyte-secreted synaptogenic protein, assembles glutamatergic synapses by bridging neurexin-1alpha and neuroligin-1B, two isoforms that do not interact with each other. Bridging of neurexin-1alpha and neuroligin-1B via hevin is critical for the formation and plasticity of thalamocortical connections in the developing visual cortex. These results show that astrocytes promote the formation of synapses by modulating neurexin/neuroligin adhesions through hevin secretion. Our findings also provide an important mechanistic insight into how mutations in these genes may lead to circuit dysfunction in diseases such as autism.

Treatment with Iodine in Pregnant Rats with Marginal Iodine Deficiency Improves Cell Migration in the Developing Brain of the Progeny.

Marginal iodine deficiency is a common health problem in pregnant women. Epidemiological and animal studies had shown that marginally maternal iodine deficiency could cause the mild changes of maternal thyroid function, eventually lead to a negative effect on neurodevelopment. But the underlying mechanisms responsible for the neurological impairment remain unclear. The aim of this study is to explore whether marginally maternal iodine deficiency could produce subtle changes in cell migration and cognitive function of offspring, and the optimal time of giving intervention to minimize the adverse effects. In the present study, we established a marginal iodine deficiency model, and iodine supplement was performed on pre-pregnancy (PP), G13 (gestation day 13), and postnatal day 0 (P0). Our data showed that there were changes in the cytoarchitecture and the percentage of bromodeoxyuridine (BrdU)-labeled cells in the cerebral cortex in marginal iodine deficiency rats. The Reelin expression was significantly lower, but Tenascin-C was higher in the cerebral cortex of marginal iodine deficiency group on P7 than the normal group, respectively. When iodine supplement, especially before G13 could reverse the abnormal expression of the two proteins involved in cell migration, which was consistent with the results of Morris Water Maze test. The three intervention groups had shorter escape latencies than the marginal iodine deficiency rats. The earlier that iodine is supplied, the better behavior performance would reach. Our findings suggested that iodine supplement in early stage of pregnancy could improve the cell migration of cerebral cortex and neurodevelopment of offspring.

In vivo clonal overexpression of neuroligin 3 and neuroligin 2 in neurons of the rat cerebral cortex: Differential effects on GABAergic synapses and neuronal migration.

We studied the effect of clonal overexpression of neuroligin 3 (NL3) or neuroligin 2 (NL2) in the adult rat cerebral cortex following in utero electroporation (IUEP) at embryonic stage E14. Overexpression of NL3 leads to a large increase in vesicular gamma-aminobutyric acid (GABA) transporter (vGAT) and glutamic acid decarboxylase (GAD)65 in the GABAergic contacts that the overexpressing neurons receive. Overexpression of NL2 produced a similar effect but to a lesser extent. In contrast, overexpression of NL3 or NL2 after IUEP does not affect vesicular glutamate transporter 1 (vGlut1) in the glutamatergic contacts that the NL3 or NL2-overexpressing neurons receive. The NL3 or NL2-overexpressing neurons do not show increased innervation by parvalbumin-containing GABAergic terminals or increased parvalbumin in the same terminals that show increased vGAT. These results indicate that the observed increase in vGAT and GAD65 is not due to increased GABAergic innervation but to increased expression of vGAT and GAD65 in the GABAergic contacts that NL3 or NL2-overexpressing neurons receive. The majority of bright vGAT puncta contacting the NL3-overexpressing neurons have no gephyrin juxtaposed to them, indicating that many of these contacts are nonsynaptic. This contrasts with the majority of the NL2-overexpressing neurons, which show plenty of synaptic gephyrin clusters juxtaposed to vGAT. Besides having an effect on GABAergic contacts, overexpression of NL3 interferes with the neuronal radial migration, in the cerebral cortex, of the neurons overexpressing NL3.

Novel interactive partners of neuroligin 3: new aspects for pathogenesis of autism.

Autism is a neurodevelopmental disorder with a strong genetic predisposition. Neurolign 3 (NLGN3) as a postsynaptic transmembrane protein, functions in both neuron synaptogenesis and glia-neuron communications. Previously, a gain of function mutation (R451C) in NLGN3 was identified in autistic patients, which illustrates the involvement of NLGN3 in autism pathogenesis. As proper synaptic targeting and functioning are controlled by intracellular protein interactions, in the current study, we tried to discover the intracellular regulation network in which NLGN3 might be involved by a yeast two-hybrid-based interactor identification. Fifty-one protein candidate partners were identified after screening a human fetal complementary DNA (cDNA) library with an intracellular fragment of NLGN3. The interactions of NLGN3 with a subset of candidates, including EEF1A1, FLNA, ITPRIP, CYP11A1, MT-CO2, GPR175, ACOT2, and QPRT, were further validated in human neuroblastoma cells or brain tissues. Furthermore, our study suggested that NLGN3 was functioning in cytosolic calcium balance and participating in calcium-regulated cellular processes. Our findings of novel NLGN3 binding partners provide evidences of involvement of NLGN3 in multiple biological pathways, especially calcium regulating and mitochondrial function, thus suggesting further significance. This new data not only leads to a better understanding of the physiological functions of NLGN3, but also provide new aspects for pathogenesis of autism.

Heat stress attenuates new cell generation in the hypothalamus: a role for miR-138.

The anterior hypothalamus (Ant Hyp) of the brain serves as the main regulator of numerous homeostatic functions, among them body temperature. Fine-tuning of the thermal-response set point during the critical postnatal sensory-developmental period involves neuronal network remodeling which might also be accompanied by alterations in hypothalamic cell populations. Here we demonstrate that heat stress during the critical period of thermal-control establishment interferes with generation of new cells in the chick hypothalamus. Whereas conditioning of the 3-day-old chicks under high ambient temperatures for 24h diminished the number of newborn cells in anterior hypothalamic structures 1 week after the treatment, mild heat stress did not influence the amount of new cells. Phenotypic analysis of these newborn cells indicated a predominant decrease in non-neuronal cell precursors, i.e. cells that do not express doublecortin (DCX). Furthermore, heat challenge of 10-day-old previously high-temperature-conditioned chicks abolished hypothalamic neurogenesis and significantly decreased the number of cells of non-neural origin. As a potential regulatory mechanism for the underlying generation of new cells in the hypothalamus, we investigated the role of the microRNA (miRNA) miR-138, previously reported by us to promote hypothalamic cell migration in vitro and whose levels are reduced during heat stress. Intracranial injection into the third ventricle of miR-138 led to an increase in the number of newborn cells in the Ant Hyp, an effect which might be partially mediated by inhibition of its direct target reelin. These data demonstrate the role of ambient temperature on the generation of new cells in the hypothalamus during the critical period of thermal-control establishment and highlight the long-term effect of severe heat stress on hypothalamic cell population. Moreover, miRNAs, miR-138 in particular, can regulate new cell generation in the hypothalamus.

Effects of prenatal hypoxia on schizophrenia-related phenotypes in heterozygous reeler mice: a gene × environment interaction study.

Both genetic and environmental factors play important roles in the pathophysiology of schizophrenia. Although prenatal hypoxia is a potential environmental factor implicated in schizophrenia, very little is known about the consequences of combining models of genetic risk factor with prenatal hypoxia. Heterozygous reeler (haploinsufficient for reelin; HRM) and wild-type (WT) mice were exposed to prenatal hypoxia (9% oxygen for two hour) or normoxia at embryonic day 17 (E17). Behavioral (Prepulse inhibition, Y-maze and Open field) and functional (regional volume in frontal cortex and hippocampus as well as hippocampal blood flow) tests were performed at 3 months of age. The levels of hypoxia and stress-related molecules such as hypoxia-inducible factor-1 α (HIF-1α), vascular endothelial factor (VEGF), VEGF receptor-2 (VEGFR2/Flk1) and glucocorticoid receptor (GR) were examined in frontal cortex and hippocampus at E18, 1 month and 3 months of age. In addition, serum VEGF and corticosterone levels were also examined. Prenatal hypoxia induced anxiety-like behavior in both HRM and WT mice. A significant reduction in hippocampal blood flow, but no change in brain regional volume was observed following prenatal hypoxia. Significant age and region-dependent changes in HIF-1α, VEGF, Flk1 and GR were found following prenatal hypoxia. Serum VEGF and corticosterone levels were found decreased following prenatal hypoxia. None of the above prenatal hypoxia-induced changes were either diminished or exacerbated due to reelin deficiency. These results argue against any gene-environment interaction between hypoxia and reelin deficiency.

Expression patterns of neuroligin-3 and tyrosine hydroxylase across the brain in mate choice contexts in female swordtails.

Choosing mates is a commonly shared behavior across many organisms, with important fitness consequences. Variations in female preferences can be due in part to differences in neural and cellular activity during mate selection. Initial studies have begun to identify putative brain regions involved in mate preference, yet the understanding of the neural processes regulating these behaviors is still nascent. In this study, we characterized the expression of a gene involved in synaptogenesis and plasticity (neuroligin-3) and one that codes for the rate-limiting enzyme in dopamine biosynthesis (tyrosine hydroxylase; TH1) in the female Xiphophorus nigrensis (northern swordtail) brain as related to mate preference behavior. We exposed females to a range of different mate choice contexts including two large courting males (LL), two small coercive males (SS), and a context that paired a large courting male with a small coercive male (LS). Neuroligin-3 expression in a mate preference context (LS) showed significant correlations with female preference in two telencephalic areas (Dm and Dl), a hypothalamic nucleus (HV), and two regions associated with sexual and social behavior (POA and Vv). We did not observe any context- or behavior-specific changes in tyrosine hydroxylase mRNA expression concomitant with female preference in any of the brain regions examined. Analysis of TH and neuroligin-3 expression across different brain regions showed that expression patterns varied with the male social environment only for neuroligin-3, where the density of correlated expression between brain regions was positively associated with mate choice contexts that involved a greater number of courting male phenotypes (LS and LL). This study identified regions showing presumed high levels of synaptic plasticity using neuroligin-3, implicating and supporting their roles in female mate preference, but we did not detect any relationship between tyrosine hydroxylase and mate preference with 30 min of stimulus presentation in X. nigrensis. These data suggest that information about potential mates is processed in select forebrain regions and the entire brain shows different degrees of correlated expression depending on the mate preference context.

MiR-138 promotes the migration of cultured chicken embryonic hypothalamic cells by targeting reelin.

Neuronal network remodeling during critical periods of sensory development might be accompanied by alterations in hypothalamic cell populations. MicroRNAs play a central role in regulating neuronal function, including neural stem cell proliferation, and neuronal migration, maturation and integration into viable circuits by modulating different mRNA targets. Here we investigated the role of miR-138 in cell proliferation and migration in a neuron-enriched hypothalamic cell culture prepared from chicks on embryonic day 16. Ectopic expression of miR-138 enhanced hypothalamic cell migration, but did not affect cell proliferation. As a potential mechanism for miR-138's effect on cell migration, we investigated reelin (Reln) as a direct target of miR-138. Luciferase reporter assay and Ago2-immunoprecipitation experiments confirmed direct binding of miR-138 to the Reln 3'-untranslated region. Ectopic miR-138 abolished Reln levels in hypothalamic cells and enhanced their migration, similar to Reln-antisense DNA. Furthermore, inhibition of Reln expression by miR-138 led to decreased phosphorylation level of the key component of Reln-regulated signaling cascades, Disabled 1. These findings describe miR-138 as a novel regulator of hypothalamic cell migration, acting at least in part via inhibition of Reln expression and leading to the inactivation of Reln signals.

A network of genetic repression and derepression specifies projection fates in the developing neocortex.

Neurons within each layer in the mammalian cortex have stereotypic projections. Four genes-Fezf2, Ctip2, Tbr1, and Satb2-regulate these projection identities. These genes also interact with each other, and it is unclear how these interactions shape the final projection identity. Here we show, by generating double mutants of Fezf2, Ctip2, and Satb2, that cortical neurons deploy a complex genetic switch that uses mutual repression to produce subcortical or callosal projections. We discovered that Tbr1, EphA4, and Unc5H3 are critical downstream targets of Satb2 in callosal fate specification. This represents a unique role for Tbr1, implicated previously in specifying corticothalamic projections. We further show that Tbr1 expression is dually regulated by Satb2 and Ctip2 in layers 2-5. Finally, we show that Satb2 and Fezf2 regulate two disease-related genes, Auts2 (Autistic Susceptibility Gene2) and Bhlhb5 (mutated in Hereditary Spastic Paraplegia), providing a molecular handle to investigate circuit disorders in neurodevelopmental diseases.

Decreased reelin expression in the left prefrontal cortex (BA9) in chronic schizophrenia patients.

BACKGROUND: Reelin is under epigenetic control and has been reported to be decreased in cortical regions in schizophrenia. METHODS: To establish if expression of reelin is altered in specific cortical, hippocampal or thalamic regions of schizophrenia patients, we measured gene expression of reelin in a postmortem study of elderly patients with schizophrenia and non-affected controls in both hemispheres differentiating between gray and white matter. We compared cerebral postmortem samples (dorsolateral prefrontal cortex BA9 and BA46, superior temporal cortex BA22, entorhinal cortex BA28, sensoric cortex BA1-3, hippocampus, CA4, mediodorsal nucleus of the thalamus) from 12 schizophrenia patients with 13 normal subjects investigating gene expression of reelin in the gray and white matter of both hemispheres by in situ-hybridization. RESULTS: The left prefrontal area (BA9) of schizophrenia patients revealed a decreased expression of reelin-mRNA of 29.1% in the white (p = 0.022) and 13.6% in the gray matter (p = 0.007) compared to the control group. None of the other regions examined showed any statistically significant differences. CONCLUSION: Since reelin is responsible for migration and synapse formation, the decreased gene expression of reelin in the left prefrontal area of schizophrenia patients points to neurodevelopmental deficits in neuronal migration and synaptic plasticity. However, our study group was small, and results should be verified using larger samples.

A forward genetic screen with a thalamocortical axon reporter mouse yields novel neurodevelopment mutants and a distinct emx2 mutant phenotype.

BACKGROUND: The dorsal thalamus acts as a gateway and modulator for information going to and from the cerebral cortex. This activity requires the formation of reciprocal topographic axon connections between thalamus and cortex. The axons grow along a complex multistep pathway, making sharp turns, crossing expression boundaries, and encountering intermediate targets. However, the cellular and molecular components mediating these steps remain poorly understood. RESULTS: To further elucidate the development of the thalamocortical system, we first created a thalamocortical axon reporter line to use as a genetic tool for sensitive analysis of mutant mouse phenotypes. The TCA-tau-lacZ reporter mouse shows specific, robust, and reproducible labeling of thalamocortical axons (TCAs), but not the overlapping corticothalamic axons, during development. Moreover, it readily reveals TCA pathfinding abnormalities in known cortical mutants such as reeler. Next, we performed an unbiased screen for genes involved in thalamocortical development using random mutagenesis with the TCA reporter. Six independent mutant lines show aberrant TCA phenotypes at different steps of the pathway. These include ventral misrouting, overfasciculation, stalling at the corticostriatal boundary, and invasion of ectopic cortical cell clusters. An outcross breeding strategy coupled with a genomic panel of single nucleotide polymorphisms facilitated genetic mapping with small numbers of mutant mice. We mapped a ventral misrouting mutant to the Emx2 gene, and discovered that some TCAs extend to the olfactory bulbs in this mutant. Mapping data suggest that other lines carry mutations in genes not previously known for roles in thalamocortical development. CONCLUSIONS: These data demonstrate the feasibility of a forward genetic approach to understanding mammalian brain morphogenesis and wiring. A robust axonal reporter enabled sensitive analysis of a specific axon tract inside the mouse brain, identifying mutant phenotypes at multiple steps of the pathway, and revealing a new aspect of the Emx2 mutant. The phenotypes highlight vulnerable choice points and latent tendencies of TCAs, and will lead to a refined understanding of the elements and interactions required to form the thalamocortical system.

Neuron-glial cell communication in the traumatic stress-induced immunomodulation.

We have previously reported that neuron and glia could collaboratively govern the immunomodulation in traumatic rats. Herein, we characterized the sequential involvement of cortical neuron, microglia, and astrocytes in the traumatic stress-mediated neuroimmune modulation. At day 1 of trauma, transient extracellular signal related kinase 1/2 (ERK1/2) activation was initiated in neuron and microglia, which was accompanied by RSK-1 expression in the cytosol. At day 3 of trauma, persistent ERK1/2 activation occurred in astrocytes, which were destined for the nucleus leading to Elk-1 expression. Furthermore, the functional overlap of ERK1/2 and neuroligin 1 in astrocytes was strengthened at day 3 of trauma and responsible for the recovery from the immnosuppression. These effects could be disrupted by ß-neurexin blockade. Altogether, we proposed the mechanism underlying the traumatic stress-induced immunosuppression, in which local activity ensured the initial establishment of neural circuitry in the frontal cortex. ERK1/2-signaling events are required for the temporal and spatial coordination between neuron and glial cells.

L-methionine decreases dendritic spine density in mouse frontal cortex.

Schizophrenia postmortem brain is characterized by gamma aminobutyric acid downregulation and by decreased dendritic spine density in frontal cortex. Protracted L-methionine treatment exacerbates schizophrenia symptoms, and our earlier work (Tremolizzo et al. and Dong et al.) has shown that L-methionine decreases reelin and GAD67 transcription in mice which is prevented by co-administration of valproate. In this study, we observed a decrease in spine density following L-methionine treatment, which was prevented by co-administration of valproate. Together with our earlier findings conducted under the same experimental conditions, we suggest that downregulation of spine density in L-methionine-treated mice may be because of the decreased expression of reelin and that valproate may prevent spine downregulation by inhibiting the methylation induced decrease in reelin.