The N-methyl-D-aspartate (NMDA) glutamate receptors play important roles in the pathophysiology of substance dependence (SD), but no strong genetic evidence has associated common variants in NMDAR-related genes to SD. We hypothesized that rare variants (RVs) with minor allele frequency <1% in the NMDAR-related genes might exert large effects on SD risk. We sequenced 34 544 bp of coding and flanking intronic regions of 17 genes involved in the NMDA system in 760 subjects, all with co-occurring alcohol dependence, cocaine dependence and opioid dependence (OD), and 760 healthy control subjects. One hundred percent of the target regions were sequenced at >1000× coverage. We identified 454 variants, including 380 RVs. Based on case-control allele count differences, we genotyped 11 exonic RVs in 6751 additional subjects, and the 1520 subjects from the sequencing stage for validation. All alleles of the 11 RVs called in the sequencing stage were confirmed. We found a statistically significant association of the 11 RVs with OD in African Americans (P = 0.00080). Results from gene-based association tests showed that the association signal derived mostly from DISC1 (P = 0.0010) and GRIN2B (P = 0.00085). DISC1 is a well-validated schizophrenia risk gene. This is the first demonstration that RVs affect the risk of OD and the first demonstration of biological convergence of schizophrenia and OD risk-via DISC1.

Up to 30% of patients with obsessive-compulsive disorder (OCD) exhibit an inadequate response to serotonin reuptake inhibitors (SRIs). To date, genetic predictors of OCD treatment response have not been systematically investigated using genome-wide association study (GWAS). To identify specific genetic variations potentially influencing SRI response, we conducted a GWAS study in 804 OCD patients with information on SRI response. SRI response was classified as 'response' (n=514) or 'non-response' (n=290), based on self-report. We used the more powerful Quasi-Likelihood Score Test (the MQLS test) to conduct a genome-wide association test correcting for relatedness, and then used an adjusted logistic model to evaluate the effect size of the variants in probands. The top single-nucleotide polymorphism (SNP) was rs17162912 (P=1.76 × 10(-8)), which is near the DISP1 gene on 1q41-q42, a microdeletion region implicated in neurological development. The other six SNPs showing suggestive evidence of association (P<10(-5)) were rs9303380, rs12437601, rs16988159, rs7676822, rs1911877 and rs723815. Among them, two SNPs in strong linkage disequilibrium, rs7676822 and rs1911877, located near the PCDH10 gene, gave P-values of 2.86 × 10(-6) and 8.41 × 10(-6), respectively. The other 35 variations with signals of potential significance (P<10(-4)) involve multiple genes expressed in the brain, including GRIN2B, PCDH10 and GPC6. Our enrichment analysis indicated suggestive roles of genes in the glutamatergic neurotransmission system (false discovery rate (FDR)=0.0097) and the serotonergic system (FDR=0.0213). Although the results presented may provide new insights into genetic mechanisms underlying treatment response in OCD, studies with larger sample sizes and detailed information on drug dosage and treatment duration are needed.

T-Brain-1 (TBR1), a causative gene in autism spectrum disorders (ASDs), encodes a brain-specific T-box transcription factor. It is therefore possible that TBR1 controls the expression of other autism risk factors. The downstream genes of TBR1 have been identified using microarray and promoter analyses. In this study, we annotated individual genes downstream of TBR1 and investigated any associations with ASDs through extensive literature searches. Of 124 TBR1 target genes, 23 were reported to be associated with ASDs. In addition, one gene, Kiaa0319, is a known causative gene for dyslexia, a disorder frequently associated with autism. A change in expression level in 10 of these 24 genes has been previously confirmed. We further validated the alteration of RNA expression levels of Kiaa0319, Baiap2, and Gad1 in Tbr1 deficient mice. Among these 24 genes, four transcription factors Auts2, Nfia, Nr4a2, and Sox5 were found, suggesting that TBR1 controls a transcriptional cascade relevant to autism pathogenesis. A further five of the 24 genes (Cd44, Cdh8, Cntn6, Gpc6, and Ntng1) encode membrane proteins that regulate cell adhesion and axonal outgrowth. These genes likely contribute to the role of TBR1 in regulation of neuronal migration and axonal extension. Besides, decreases in Grin2b expression and increases in Gad1 expression imply that neuronal activity may be aberrant in Tbr1 deficient mice. These analyses provide direction for future experiments to reveal the pathogenic mechanism of autism.

Bipolar disorder (BD) shows one of the strongest genetic predispositions among psychiatric disorders and the identification of reliable genetic predictors of treatment response could significantly improve the prognosis of the disease. The present study investigated genetic predictors of long-term treatment-outcome in 723 patients with BD type I from the STEP-BD (Systematic Treatment Enhancement Program for Bipolar Disorder) genome-wide dataset. BD I patients with >6months of follow-up and without any treatment restriction (reflecting a natural setting scenario) were included. Phenotypes were the total and depressive episode rates and the occurrence of one or more (hypo)manic/mixed episodes during follow-up. Quality control of genome-wide data was performed according to standard criteria and linear/logistic regression models were used as appropriate under an additive hypothesis. Top genes were further analyzed through a pathway analysis. Genes previously involved in the susceptibility to BD (DFNB31, SORCS2, NRXN1, CNTNAP2, GRIN2A, GRM4, GRIN2B), antidepressant action (DEPTOR, CHRNA7, NRXN1), and mood stabilizer or antipsychotic action (NTRK2, CHRNA7, NRXN1) may affect long-term treatment outcome of BD. Promising findings without previous strong evidence were TRAF3IP2-AS1, NFYC, RNLS, KCNJ2, RASGRF1, NTF3 genes. Pathway analysis supported particularly the involvement of molecules mediating the positive regulation of MAPK cascade and learning/memory processes. Further studies focused on the outlined genes may be helpful to provide validated markers of BD treatment outcome.

BACKGROUND

The glutamatergic neurotransmitter systems play a crucial role in memory formation and information processing. Alterations in this system contribute to the manifestation of symptoms in Alzheimer's disease (AD). Glutamate transmits signals via the N-methyl-D-aspartate receptors (NMDARs).

OBJECTIVE

The potential involvement of polymorphisms in the GRIN2B gene, encoding subunit 2B of the NMDA receptor, in the risk for AD was evaluated.

METHODS

We investigated the 3 single-nucleotide polymorphisms (SNPs) rs1019385, rs1806201 and rs890, i.e. the G(-200)->>T transversion in the 5'UTR, the A(2664)->>G transition in exon 13 and the G(5072)->>T transition in the 3'UTR of the GRIN2B gene, in 222 Caucasian AD patients and 170 healthy Caucasian age-matched controls.

RESULTS

No differences were found in the overall distribution of the single-nucleotide polymorphism genotypes between AD patients and healthy controls, even when the analysis was adjusted for sex, age and APOE. As expected from genotype frequencies, no differences were found in the distribution of the estimated allele and haplotype frequencies between AD patients and healthy controls.

CONCLUSIONS

In this study no significant association between polymorphisms in the GRIN2B gene and AD was observed. Further investigations of polymorphisms in the gene encoding the NMDA receptor 2B subunit in AD patients with different genetic setting are needed to clarify their role in the pathogenesis of AD.

Chronic alcohol consumption may result in sustained gene expression alterations in the brain, leading to alcohol abuse or dependence. Because of ethical concerns of using live human brain cells in research, this hypothesis cannot be tested directly in live human brains. In the present study, we used human embryonic stem cell (hESC)-derived cortical neurons as in vitro cellular models to investigate alcohol-induced expression changes of genes involved in alcohol metabolism (ALDH2), anti-apoptosis (BCL2 and CCND2), neurotransmission (NMDA receptor subunit genes: GRIN1, GRIN2A, GRIN2B, and GRIN2D), calcium channel activity (ITPR2), or transcriptional repression (JARID2). hESCs were differentiated into cortical neurons, which were characterized by immunostaining using antibodies against cortical neuron-specific biomarkers. Ethanol-induced gene expression changes were determined by reverse-transcription quantitative polymerase chain reaction (RT-qPCR). After a 7-day ethanol (50 mM) exposure followed by a 24-hour ethanol withdrawal treatment, five of the above nine genes (including all four NMDA receptor subunit genes) were highly upregulated (GRIN1: 1.93-fold, P = 0.003; GRIN2A: 1.40-fold, P = 0.003; GRIN2B: 1.75-fold, P = 0.002; GRIN2D: 1.86-fold, P = 0.048; BCL2: 1.34-fold, P = 0.031), and the results of GRIN1, GRIN2A, and GRIN2B survived multiple comparison correction. Our findings suggest that alcohol responsive genes, particularly NMDA receptor genes, play an important role in regulating neuronal function and mediating chronic alcohol consumption-induced neuroadaptations.

The postnatal functions of the Dlx1&2 transcription factors in cortical interneurons (CINs) are unknown. Here, using conditional Dlx1, Dlx2, and Dlx1&2 knockouts (CKOs), we defined their roles in specific CINs. The CKOs had dendritic, synaptic, and survival defects, affecting even PV+ CINs. We provide evidence that DLX2 directly drives Gad1, Gad2, and Vgat expression, and show that mutants had reduced mIPSC amplitude. In addition, the mutants formed fewer GABAergic synapses on excitatory neurons and had reduced mIPSC frequency. Furthermore, Dlx1/2 CKO had hypoplastic dendrites, fewer excitatory synapses, and reduced excitatory input. We provide evidence that some of these phenotypes were due to reduced expression of GRIN2B (a subunit of the NMDA receptor), a high confidence Autism gene. Thus, Dlx1&2 coordinate key components of CIN postnatal development by promoting their excitability, inhibitory output, and survival.

Autism (MIM 209850) is a complex neurodevelopmental disorder characterized by social communication impairments and restricted repetitive behaviors. It has a high heritability, although much remains unclear. To evaluate genetic variants of GRIN2B in autism etiology, we performed a system association study of common and rare variants of GRIN2B and autism in cohorts from a Chinese population, involving a total sample of 1,945 subjects. Meta-analysis of a triad family cohort and a case-control cohort identified significant associations of multiple common variants and autism risk (Pmin = 1.73 × 10(-4)). Significantly, the haplotype involved with the top common variants also showed significant association (P = 1.78 × 10(-6)). Sanger sequencing of 275 probands from a triad cohort identified several variants in coding regions, including four common variants and seven rare variants. Two of the common coding variants were located in the autism-related linkage disequilibrium (LD) block, and both were significantly associated with autism (P < 9 × 10(-3)) using an independent control cohort. Burden analysis and case-only analysis of rare coding variants identified by Sanger sequencing did not find this association. Our study for the first time reveals that common variants and related haplotypes of GRIN2B are associated with autism risk.

OBJECTIVE

In humans, depending on dose, blocking the N-methyl-D-aspartate receptor (NMDAR) with ketamine can cause psychomimetic or antidepressant effects. The overall outcome for drugs such as ketamine depends on dose and the number of its available binding sites in the central nervous system, and to understand something of the latter variable we measure NMDAR in the frontal pole, dorsolateral prefrontal, anterior cingulate and parietal cortices from people with schizophrenia, bipolar disorder, major depressive disorders and age/sex matched controls.

METHODS

We measured levels of NMDARs (using [(3)H]MK-801 binding) and NMDAR sub-unit mRNAs (GRINs: using in situ hybridisation) as well as post-synaptic density protein 95 (anterior cingulate cortex only; not major depressive disorders: an NMDAR post-synaptic associated protein) in bipolar disorder, schizophrenia and controls.

RESULTS

Compared to controls, levels of NMDAR were lower in the outer laminae of the dorsolateral prefrontal cortex (-17%, p = 0.01) in people with schizophrenia. In bipolar disorder, levels of NMDAR binding (laminae IV-VI; -19%, p < 0.01) and GRIN2C mRNA (laminae I-VI; -27%, p < 0.05) were lower in the anterior cingulate cortex and NMDAR binding was lower in the outer lamina IV of the dorsolateral prefrontal cortex (-19%, p < 0.01). In major depressive disorders, levels of GRIN2D mRNA were higher in frontal pole (+22%, p < 0.05). In suicide completers, levels of GRIN2B mRNA were higher in parietal cortex (+20%, p < 0.01) but lower (-35%, p = 0.02) in dorsolateral prefrontal cortex while post-synaptic density protein 95 was higher (+26%, p < 0.05) in anterior cingulate cortex.

CONCLUSIONS

These data suggest that differences in cortical NMDAR expression and post-synaptic density protein 95 are present in psychiatric disorders and suicide completion and may contribute to different responses to ketamine.

Diseases caused by single-gene mutations can display substantial phenotypic variability, which may be due to genetic, environmental, or epigenetic modifiers. Here, we induce Gaucher disease (GD), a rare inherited metabolic disorder, by injecting 15 inbred mouse strains with a low dose of a chemical inhibitor of acid β-glucosidase, the enzyme defective in GD. Different mouse strains exhibit widely different lifespans, which is unrelated to levels of acid β-glucosidase's substrate accumulation. Genome-wide association reveals a number of candidate risk loci, including a marker within Grin2b, which in combination with another marker allows us to predict the lifespan of additional mouse strains. An antagonist of the NMDA receptor (encoded by Grin2b) significantly increases the lifespan of GD mice that would otherwise have lived for a short time. Our data identify putative modifier genes that may be involved in determining GD severity, which might help elucidate phenotypic variability between patients with similar GD mutations.

In the present work we genotyped three single-nucleotide polymorphisms (SNPs) (rs7301328, rs1805247, and rs1805502) of the GRIN2B gene in a set of 480 unrelated bipolar disorder patients and 480 unrelated genetically matched normal controls in Chinese Han population by either allelic-specific multiplex ligation-detection reaction (AMLR) technology or direct sequencing. Rs1805247 and the haplotype consisting of rs1805502 and rs1805247 were significantly associated, suggesting GRIN2B as having a role in the etiology of bipolar disorder.

OBJECTIVE

Venlafaxine (VLX), a serotonine-noradrenaline reuptake inhibitor, is one of the most commonly used antidepressant drugs in clinical practice for the treatment of major depressive disorder (MDD). Despite being more potent than its predecessors, similarly to them, the therapeutical effect of VLX is visible only 3-4 weeks after the beginning of treatment. Furthermore, recent papers show that antidepressants, including also VLX, enhance the motor recovery after stroke even in non depressed persons. In the present, transcriptomic-based study we looked for changes in gene expressions after a long-term VLX administration.

METHODS

Osmotic minipumps were implanted subcutaneously into Dark Agouti rats providing a continuous (40 mg/kg/day) VLX delivery for three weeks. Frontal regions of the cerebral cortex were isolated and analyzed using Illumina bead arrays to detect genes showing significant chances in expression. Gene set enrichment analysis was performed to identify specific regulatory networks significantly affected by long term VLX treatment.

RESULTS

Chronic VLX administration may have an effect on neurotransmitter release via the regulation of genes involved in vesicular exocytosis and receptor endocytosis (such as Kif proteins, Myo5a, Sv2b, Syn2 or Synj2). Simultaneously, VLX activated the expression of genes involved in neurotrophic signaling (Ntrk2, Ntrk3), glutamatergic transmission (Gria3, Grin2b and Grin2a), neuroplasticity (Camk2g/b, Cd47), synaptogenesis (Epha5a, Gad2) and cognitive processes (Clstn2). Interestingly, VLX increased the expression of genes involved in mitochondrial antioxidant activity (Bcl2 and Prdx1). Additionally, VLX administration also modulated genes related to insulin signaling pathway (Negr1, Ppp3r1, Slc2a4 and Enpp1), a mechanism that has recently been linked to neuroprotection, learning and memory.

CONCLUSIONS

Our results strongly suggest that chronic VLX treatment improves functional reorganization and brain plasticity by influencing gene expression in regulatory networks of motor cortical areas. These results are consonant with the synaptic (network) hypothesis of depression and antidepressant-induced motor recovery after stroke.

Glutamate is an important excitatory neurotransmitter within functional prefrontal-basal ganglia loops. These distinct loops mediate different cognitive functions. One function of the anterior-cingulate loop is error processing. One function of the orbito-frontal loop is response inhibition. These functions are altered in several neuro-psychiatric disorders like Huntington's disease (HD). Because of the known role of the GRIN2B C2664T polymorphism in HD neuropathology, which is partly due to increased glutamatergic neural transmission, we analyze how this polymorphism influences error processing and response inhibition in a sample of healthy probands (N=65). Combining a genetic approach with event-related potential (ERP) measurements of response inhibition (OFC-loop function) and error processing (ACC-loop function), we provide robust results showing a selective modulation of response inhibition processes by the GRIN2B C2664T polymorphism at the behavioural and neurophysiological level. Response inhibition processes were stronger in the CT/TT genotype group, compared to the CC genotype group. Since error processing functions were not affected, the results suggest for differential influences of the GRIN2B C2664T polymorphism on response inhibition and error processing functions. The results provide first insight into cognitive-neurophysiological effects of the GRIN2B C2664T polymorphism. The dissociation obtained may be due to a differential importance of N-methyl-D-aspartate receptors for glutamatergic neural transmission in different striatal compartments (matrix and striosomes). We provide a model on this that may be a target for future research.

Tardive dyskinesia (TD) is a neurological disorder characterized by irregular, non-rhythmic, choreoathetotic and involuntary movements in single or multiple body regions. Chronic administration of typical antipsychotic agents, which predominantly act on dopamine receptors, implicates the dopamine system in susceptibility to TD. An alternative to this dopaminergic supersensivity hypothesis in understanding the pathogenesis of TD is the glutamatergic neurotoxicity hypothesis, which implicates the N-methyl-D-aspartate (NMDA) receptor in TD pathogenesis. In the present study, the association between three polymorphisms (T-200G, C366G and C2664T) of the GRIN2B gene, which encodes the 2B subunit of the NMDA receptor, and the occurrence and severity of TD were investigated in 273 Chinese schizophrenic patients receiving long-term antipsychotic treatment (TD: 142, non-TD: 133). There was no significant association between patients' genotype and allele frequencies and TD occurrence. Among the TD patients, the differences in the total scores on the Abnormal Involuntary Movement Scale (AIMS) among the three genotypes of each polymorphism were not significant. Because the three studied markers are in weak linkage disequilibrium with each other, haplotype-based association was not carried out. We conclude that genetic variations in the human GRIN2B gene probably do not play a major role in susceptibility to, or severity of TD.

OBJECTIVE

To identify the reliable connectivity between causal genes or variants with an abnormality expressed in a certain endophenotype has been viewed as a crucial step in unraveling the etiology of schizophrenia because of the considerable heterogeneity in this disorder.

METHODS

According to this practical and scientific demand, we aimed to investigate the relationship between seven top-ranked variants in the SZgene database [120-bpTR in DRD4, rs1801028 and rs6277 in DRD2, rs1019385 (T200G) in GRIN2B, rs1800532 in TPH1, rs1801133 (C677T) in MTHFR, rs2619528 (P1765) in DTNBP1] and prepulse inhibition (PPI) and habituation after acoustic stimulus (HAB).

RESULTS

Both PPI and HAB were decreased significantly in patients with schizophrenia. In addition, we observed a significant effect of GRIN2B (human NMDA receptor 2B subunit gene, NR2B) genotype on HAB (P<0.05, not corrected).

CONCLUSIONS

Although these findings need to be replicated in other samples, an underlying mechanism of impaired biological reaction may be influenced by NMDA hypofunctioning in schizophrenia.

The kinesin superfamily of motor proteins is known to be ATP-dependent transporters of various types of cargoes. In neurons, KIF17 is found to transport vesicles containing the N-methyl-D-aspartate receptor NR2B subunit from the cell body specifically to the dendrites. These subunits are intimately associated with glutamatergic neurotransmission as well as with learning and memory. Glutamatergic synapses are highly energy-dependent, and recently we found that the same transcription factor, nuclear respiratory factor 1 (NRF-1), co-regulates energy metabolism (via its regulation of cytochrome c oxidase and other mitochondrial enzymes) and neurochemicals of glutamatergic transmission (NR1, NR2B, GluR2, and nNOS). The present study tested our hypothesis that NRF-1 also transcriptionally regulates KIF17. By means of in silico analysis, electrophoretic mobility shift and supershift assays, in vivo chromatin immunoprecipitation assays, promoter mutations, and real-time quantitative PCR, we found that NRF-1 (but not NRF-2) functionally regulates Kif17, but not Kif1a, gene. NRF-1 binding sites on Kif17 gene are highly conserved among mice, rats, and humans. Silencing of NRF-1 with small interference RNA blocked the up-regulation of Kif17 mRNA and proteins (and of Grin1 and Grin2b) induced by KCl-mediated depolarization, whereas over-expressing NRF-1 rescued these transcripts and proteins from being suppressed by TTX. Thus, NRF-1 co-regulates oxidative enzymes that generate energy and neurochemicals that consume energy related to glutamatergic neurotransmission, such as KIF17, NR1, and NR2B, thereby ensuring that energy production matches energy utilization at the molecular and cellular levels.

Insight into the biological pathomechanism of a clinical syndrome facilitates the development of effective interventions. This paper applies this perspective to the important clinical problem of obsessive-compulsive symptoms (OCS) occurring during the lifetime diagnosis of schizophrenia. Up to 25% of schizophrenia patients suffer from OCS and about 12% fulfil the diagnostic criteria of obsessive-compulsive disorder (OCD). This is accompanied by marked subjective burden of disease, high levels of anxiety, depression and suicidality, increased neurocognitive impairment, less favourable levels of social and vocational functioning, and greater service utilization. Comorbid patients can be assigned to heterogeneous subgroups. It is assumed that second generation antipsychotics (SGAs), most importantly clozapine, might aggravate or even induce second-onset OCS. Several epidemiological and pharmacological arguments support this assumption. Specific genetic risk factors seem to dispose patients with schizophrenia to develop OCS and risk-conferring polymorphisms has been defined in SLC1A1, BDNF, DLGAP3, and GRIN2B and in interactions between these individual genes. Further research is needed with detailed characterization of large samples. In particular interactions between genetic risk constellations, pharmacological and psychosocial factors should be analysed. Results will further define homogeneous subgroups, which are in need for differential causative interventions. In clinical practise, schizophrenia patients should be carefully monitored for OCS, starting with at-risk mental states of psychosis and longitudinal follow-ups, hopefully leading to the development of multimodal therapeutic interventions.

Multiple animal models have been developed to recapitulate phenotypes of the human disease, schizophrenia. A model that simulates many of the cognitive and sensory deficits of the disorder is the use of random variable prenatal stress (PS) in the rat. These deficits suggest a molecular origin in the hippocampus, a brain region that plays a role in the regulation of stress. To study both hippocampal gene expression changes in offspring of prenatally stressed dams and to address genetic variability, we used a random array of prenatal stressors in three different rat strains with diverse responses to stress: Fischer, Sprague-Dawley, and Lewis rats. Candidate genes involved in stress, schizophrenia, cognition, neurotrophic effects, and immunity were selected for assessment by real-time quantitative PCR under resting conditions and following a brief exposure to restraint stress. PS resulted in significant differences in gene expression in the offspring that were strain dependent. mRNA expression for the N-methyl-D-aspartate receptor subtype 2B (Grin2b) was increased, and tumor necrosis factor-alpha (Tnfα) transcript was decreased in PS Sprague-Dawley and Lewis rats, but not in the Fischer rats. Expression of brain-derived neurotrophic factor (Bdnf) mRNA in the hippocampus was increased after an acute stress in all controls of each strain, yet a decrease was seen after acute stress in the PS Sprague-Dawley and Lewis rats. Expression of the glucocorticoid receptor (Nr3c1) was decreased in the Fischer strain when compared to Lewis or Sprague-Dawley rats, though the Fischer rats had markedly higher α7 nicotinic receptor (Chrna7) expression. The expression differences seen in these animals may be important elements of the phenotypic differences seen due to PS and genetic background.

Paeoniflorin (PF) is a main bioactive component of the root of Paeonia lactiflora Pal, and previous investigations suggest that it may impact cardiac remodeling in spontaneous hypertensive rats (SHR) via the MAPK signaling pathway. Thus, the purpose of this investigation was to examine the impacts of paeoniflorin cardiac function in SHR rats. Cardiac function and blood pressure were observed using echocardiography and non-invasive tail pressure gauge. Heart histopathology was assessed by histological staining and transmission electron microscopy. Genomic sequencing was performed and signaling pathway enrichment analyzed the function of differentially expressed genes(DEGs). Biochemical kits were used to analyze the serum level of proinflammatory cytokines including TNF-α, IL-6 and MCP-1. qRT-PCR proved the mRNA expression of Ngfr, Grin2b, and Ntf4. MAPK pathways were determined via western blot. Paeoniflorin decreased blood pressure and increased hemodynamic indexes. 131 DEGs were identified (SHR vs. PF), and mainly enriched on the MAPK signaling pathway. Paeoniflorin reduced IL-6, MCP-1, Ngfr, Grin2b, and Ntf4, and also decreased p-JNK, p-Erk1/2, and p-p38 proteins compared with the SHR group. Paeoniflorin attenuated cardiac hypertrophy, cardiac fibrosis, and inflammation, and subsequently improved LV function. In conclusion, the cardioprotective role of paeoniflorin was associated with the inhibition of MAPK signaling pathway.

BACKGROUND

The purpose of this study was to investigate the association between the ionotropic and glutamate receptors, N-methyl D-asparate 2A (GRIN2A) and 2B (GRIN2B), and the metabotropic glutamate receptor mGluR7 (GRM7) gene polymorphisms and attention-deficit hyperactivity disorder (ADHD) in Korean population.

METHODS

We conducted a case-control analysis of 202 ADHD subjects and 159 controls, performed a transmission disequilibrium test (TDT) on 149 trios, and compared scores from the continuous performance test (CPT), the Children's Depression Inventory (CDI), and the State-Trait Anxiety Inventory for Children (STAIC) according to the genotype of the glutamate receptor genes.

RESULTS

There were no significant differences in the genotype or allele frequencies of the GRIN2A rs8049651, GRIN2B rs2284411, or GRM7 rs37952452 polymorphisms between the ADHD and control groups. For 148 ADHD trios, the TDT analysis also showed no preferential transmission of the GRIN2A rs8049651 or GRIN2B rs2284411 polymorphisms. However, the TDT analysis of the GRM7 rs3792452 polymorphism showed biased transmission of the G allele (χ2 = 4.67, p = 0.031). In the ADHD probands, the subjects with GG genotype in the GRM7 rs37952452 polymorphism had higher mean T-scores for omission errors on the CPT than did those with the GA or AA genotype (t = 3.38, p = 0.001). In addition, the ADHD subjects who were homozygous for the G allele in the GRM7 rs37952452 polymorphism had higher STAIC-T (t = 5.52, p < 0.001) and STAIC-S (t = 2.74, p = 0.007) scores than did those with the GA or AA genotype.

CONCLUSIONS

These results provide preliminary evidence of an association between the GRM7 rs37952452 polymorphism and selective attention deficit and anxiety found within the Korean ADHD population.

It is known that a syndrome resembling schizophrenia is produced by the N-methyl-d-aspartate receptor antagonists. It has also been demonstrated that the level of an ionotropic N-methyl-d-aspartate 2B subunit (GRIN2B) of the glutamate receptor tends to increase after subchronic administration of clozapine, suggesting that GRIN2B may play an active role in the pathogenesis of schizophrenia and the function of clozapine medication. We studied 100 schizophrenic patients, investigating the associations for the GRIN2B genetic variants, and psychiatric symptoms and clozapine response. No significant differences were demonstrated comparing these three groups in terms of the baseline Brief Psychiatric Rating Scale (BPRS) score (P = 0.441). The percentage of patients scoring within 20% of baseline BPRS after clozapine treatment was similar for the three genotype groups (P = 0.132). A marginally higher mean clozapine dosage was revealed, however, for patients bearing the 2664C/C genotype (P = 0.013). Although replication of this research is required to confirm the results, an association for the GRIN2B C2664T polymorphism and clozapine treatment is suggested from our findings, which may assist in the prediction of optimal dosage for schizophrenic patients.

N-methyl d-aspartate receptors (NMDARs), a subtype of glutamate receptor, have important functional roles in cellular activity and neuronal development. They are well-studied in rodent and adult human brains, but limited information is available about their distribution in the human fetal cerebral cortex. Here we show that 3 NMDAR subunits, NR1, NR2A, and NR2B, are expressed in the human cerebral cortex during the second trimester of gestation, a period of intense neurogenesis and synaptogenesis. With increasing fetal age, expression of the NMDAR-encoding genes Grin1 (NR1) and Grin2a (NR2A) increased while Grin2b (NR2B) expression decreased. The protein levels of all 3 subunits paralleled the changes in gene expression. On cryosections, all 3 subunits were expressed in proliferative ventricular and subventricular zones, in radial glia, and in intermediate progenitor cells, consistent with their role in the proliferation of cortical progenitor cells and in the determination of their respective fates. The detection of NR1, NR2A, and NR2B in both glutamatergic and GABAergic neurons of the cortical plate suggests the involvement of NMDARs in the maturation of human cortical neurons and in early synapse formation. Our results and previous studies in rodents suggest that NMDAR expression in the developing human brain is evolutionarily conserved.

We investigated three polymorphisms in the NMDA receptor 2B subunit gene (GRIN2B) as a candidate gene for lithium response involved in glutamatergic neurotransmission. One hundred five bipolar patients treated with lithium for at least 5 years were analyzed. The lithium response was assessed as excellent - no affective episodes during lithium treatment; partial - 50% reduction in the episode index; or no response - less than 50% reduction, no change or worsening in the episode index. Genotypes for the -200G/T, 366C/G and rs890G/T GRIN2B polymorphisms were established using the PCR-RFLP method. Genotype distributions were in Hardy-Weinberg equilibrium for all three polymorphisms. No association was found between the three polymorphisms studied and the treatment response to lithium. The authors conclude that polymorphisms of the GRIN2B gene did not show an association with the treatment response to lithium in bipolar patients.

Heterozygous loss-of-function mutations in GRIN2B, a subunit of the NMDA receptor, cause intellectual disability and language impairment. We developed clonal models of GRIN2B deletion and loss-of-function mutations in a region coding for the glutamate binding domain in human cells and generated neurons from a patient harboring a missense mutation in the same domain. Transcriptome analysis revealed extensive increases in genes associated with cell proliferation and decreases in genes associated with neuron differentiation, a result supported by extensive protein analyses. Using electrophysiology and calcium imaging, we demonstrate that NMDA receptors are present on neural progenitor cells and that human mutations in GRIN2B can impair calcium influx and membrane depolarization even in a presumed undifferentiated cell state, highlighting an important role for non-synaptic NMDA receptors. It may be this function, in part, which underlies the neurological disease observed in patients with GRIN2B mutations.