The origin of esterase activity of Parkinson's disease causative factor DJ-1 implied by evolutionary trace analysis of its prokaryotic homolog HchA.

DJ-1, a causative gene for hereditary recessive Parkinsonism, is evolutionarily conserved across eukaryotes and prokaryotes. Structural analyses of DJ-1 and its homologs suggested the 106th Cys is a nucleophilic cysteine functioning as the catalytic center of hydratase or hydrolase activity. Indeed, DJ-1 and its homologs can convert highly electrophilic α-oxoaldehydes such as methylglyoxal into α-hydroxy acids as hydratase in vitro, and oxidation-dependent ester hydrolase (esterase) activity has also been reported for DJ-1. The mechanism underlying such plural activities, however, has not been fully characterized. To address this knowledge gap, we conducted a series of biochemical assays assessing the enzymatic activity of DJ-1 and its homologs. We found no evidence for esterase activity in any of the Escherichia coli DJ-1 homologs. Furthermore, contrary to previous reports, we found that oxidation inactivated rather than facilitated DJ-1 esterase activity. The E. coli DJ-1 homolog HchA possesses phenylglyoxalase and methylglyoxalase activities but lacks esterase activity. Since evolutionary trace analysis identified the 186th H as a candidate residue involved in functional differentiation between HchA and DJ-1, we focused on H186 of HchA and found that an esterase activity was acquired by H186A mutation. Introduction of reverse mutations into the equivalent position in DJ-1 (A107H) selectively eliminated its esterase activity without compromising α-oxoaldehyde hydratase activity. The obtained results suggest that differences in the amino acid sequences near the active site contributed to acquisition of esterase activity in vitro and provide an important clue to the origin and significance of DJ-1 esterase activity.

Foxp1 regulation of neonatal vocalizations via cortical development.

The molecular mechanisms driving brain development at risk in autism spectrum disorders (ASDs) remain mostly unknown. Previous studies have implicated the transcription factor FOXP1 in both brain development and ASD pathophysiology. However, the specific molecular pathways both upstream of and downstream from FOXP1 are not fully understood. To elucidate the contribution of FOXP1-mediated signaling to brain development and, in particular, neocortical development, we generated forebrain-specific Foxp1 conditional knockout mice. We show that deletion of Foxp1 in the developing forebrain leads to impairments in neonatal vocalizations as well as neocortical cytoarchitectonic alterations via neuronal positioning and migration. Using a genomics approach, we identified the transcriptional networks regulated by Foxp1 in the developing neocortex and found that such networks are enriched for downstream targets involved in neurogenesis and neuronal migration. We also uncovered mechanistic insight into Foxp1 function by demonstrating that sumoylation of Foxp1 during embryonic brain development is necessary for mediating proper interactions between Foxp1 and the NuRD complex. Furthermore, we demonstrated that sumoylation of Foxp1 affects neuronal differentiation and migration in the developing neocortex. Together, these data provide critical mechanistic insights into the function of FOXP1 in the developing neocortex and may reveal molecular pathways at risk in ASD.

Copy number variations in RNF216 and postsynaptic membrane-associated genes are associated with bipolar disorder: a case-control study in the Japanese population.

AIM: Bipolar disorder (BD) is a common psychiatric disorder characterized by alterations between manic/hypomanic and depressive states. Rare pathogenic copy number variations (CNVs) that overlap with exons of synaptic genes have been associated with BD. However, no study has comprehensively explored CNVs in synaptic genes associated with BD. Here, we evaluated the relationship between BD and rare CNVs that overlap with synaptic genes, not limited to exons, in the Japanese population. METHODS: Using array comparative genome hybridization, we detected CNVs in 1839 patients with BD and 2760 controls. We used the Synaptic Gene Ontology database to identify rare CNVs that overlap with synaptic genes. Using gene-based analysis, we compared their frequencies between the BD and control groups. We also searched for synaptic gene sets related to BD. The significance level was set to a false discovery rate of 10%. RESULTS: The RNF216 gene was significantly associated with BD (odds ratio, 4.51 [95% confidence interval, 1.66-14.89], false discovery rate < 10%). The BD-associated CNV that corresponded with RNF216 also partially overlapped with the minimal critical region of the 7p22.1 microduplication syndrome. The integral component of the postsynaptic membrane (Gene Ontology:0099055) was significantly associated with BD. The CNV overlapping with the intron region of GRM5 in this gene set showed a nominal significant association between cases and controls (P < 0.05). CONCLUSION: We provide evidence that CNVs in RNF216 and postsynaptic membrane-related genes confer a risk of BD, contributing to a better understanding of the pathogenesis of BD.

Accelerated evolution of oligodendrocytes in the human brain.

Recent discussions of human brain evolution have largely focused on increased neuron numbers and changes in their connectivity and expression. However, it is increasingly appreciated that oligodendrocytes play important roles in cognitive function and disease. Whether both cell types follow similar or distinctive evolutionary trajectories is not known. We examined the transcriptomes of neurons and oligodendrocytes in the frontal cortex of humans, chimpanzees, and rhesus macaques. We identified human-specific trajectories of gene expression in neurons and oligodendrocytes and show that both cell types exhibit human-specific up-regulation. Moreover, oligodendrocytes have undergone more pronounced accelerated gene expression evolution in the human lineage compared to neurons. We highlighted human-specific coexpression networks with specific functions. Our data suggest that oligodendrocyte human-specific networks are enriched for alternative splicing and transcriptional regulation. Oligodendrocyte networks are also enriched for variants associated with schizophrenia and other neuropsychiatric disorders. Such enrichments were not found in neuronal networks. These results offer a glimpse into the molecular mechanisms of oligodendrocytes during evolution and how such mechanisms are associated with neuropsychiatric disorders.

Foxp1 in Forebrain Pyramidal Neurons Controls Gene Expression Required for Spatial Learning and Synaptic Plasticity.

Genetic perturbations of the transcription factor Forkhead Box P1 (FOXP1) are causative for severe forms of autism spectrum disorder that are often comorbid with intellectual disability. Recent work has begun to reveal an important role for FoxP1 in brain development, but the brain-region-specific contributions of Foxp1 to autism and intellectual disability phenotypes have yet to be determined fully. Here, we describe Foxp1 conditional knock-out (Foxp1cKO) male and female mice with loss of Foxp1 in the pyramidal neurons of the neocortex and the CA1/CA2 subfields of the hippocampus. Foxp1cKO mice exhibit behavioral phenotypes that are of potential relevance to autism spectrum disorder, including hyperactivity, increased anxiety, communication impairments, and decreased sociability. In addition, Foxp1cKO mice have gross deficits in learning and memory tasks of relevance to intellectual disability. Using a genome-wide approach, we identified differentially expressed genes in the hippocampus of Foxp1cKO mice associated with synaptic function and development. Furthermore, using magnetic resonance imaging, we uncovered a significant reduction in the volumes of both the entire hippocampus as well as individual hippocampal subfields of Foxp1cKO mice. Finally, we observed reduced maintenance of LTP in area CA1 of the hippocampus in these mutant mice. Together, these data suggest that proper expression of Foxp1 in the pyramidal neurons of the forebrain is important for regulating gene expression pathways that contribute to specific behaviors reminiscent of those seen in autism and intellectual disability. In particular, Foxp1 regulation of gene expression appears to be crucial for normal hippocampal development, CA1 plasticity, and spatial learning.SIGNIFICANCE STATEMENT Loss-of-function mutations in the transcription factor Forkhead Box P1 (FOXP1) lead to autism spectrum disorder and intellectual disability. Understanding the potential brain-region-specific contributions of FOXP1 to disease-relevant phenotypes could be a critical first step in the management of patients with these mutations. Here, we report that Foxp1 conditional knock-out (Foxp1cKO) mice with loss of Foxp1 in the neocortex and hippocampus display autism and intellectual-disability-relevant behaviors. We also show that these phenotypes correlate with changes in both the genomic and physiological profiles of the hippocampus in Foxp1cKO mice. Our work demonstrates that brain-region-specific FOXP1 expression may relate to distinct, clinically relevant phenotypes.

Pyridoxamine: A novel treatment for schizophrenia with enhanced carbonyl stress.

AIM: The aim of this clinical trial was to obtain proof of concept for high-dose pyridoxamine as a novel treatment for schizophrenia with enhanced carbonyl stress. METHODS: Ten Japanese schizophrenia patients with high plasma pentosidine, which is a representative biomarker of enhanced carbonyl stress, were recruited in a 24-week, open trial in which high-dose pyridoxamine (ranging from 1200 to 2400 mg/day) was administered using a conventional antipsychotic regimen. Main outcomes were the total change in Positive and Negative Syndrome Scale score and the Brief Psychiatric Rating Scale score from baseline to end of treatment at week 24 (or at withdrawal). RESULTS: Decreased plasma pentosidine levels were observed in eight patients. Two patients showed marked improvement in their psychological symptoms. A patient who harbors a frameshift mutation in the Glyoxalase 1 gene also showed considerable reduction in psychosis accompanied with a moderate decrease in plasma pentosidine levels. A reduction of greater than 20% in the assessment scale of drug-induced Parkinsonism occurred in four patients. Although there was no severe suicide-related ideation or behavior, Wernicke's encephalopathy-like adverse drug reactions occurred in two patients and were completely suppressed by thiamine supplementation. CONCLUSION: High-dose pyridoxamine add-on treatment was, in part, effective for a subpopulation of schizophrenia patients with enhanced carbonyl stress. Further randomized, placebo-controlled trials with careful monitoring will be required to validate the efficacy of high-dose pyridoxamine for these patients.

The regulation of soluble receptor for AGEs contributes to carbonyl stress in schizophrenia.

Our previous study showed that enhanced carbonyl stress is closely related to schizophrenia. The endogenous secretory receptor for advanced glycation end-products (esRAGE) is a splice variant of the AGER gene and is one of the soluble forms of RAGE. esRAGE is considered to be a key molecule for alleviating the burden of carbonyl stress by entrapping advanced glycation end-products (AGEs). In the current study, we conducted genetic association analyses focusing on AGER, in which we compared 212 schizophrenic patients to 214 control subjects. We also compared esRAGE levels among a subgroup of 104 patients and 89 controls and further carried out measurements of total circulating soluble RAGE (sRAGE) in 25 patients and 49 healthy subjects. Although the genetic association study yielded inconclusive results, multiple regression analysis indicated that a specific haplotype composed of rs17846798, rs2071288, and a 63 bp deletion, which were in perfect linkage disequilibrium (r2 = 1), and rs2070600 (Gly82Ser) were significantly associated with a marked decrease in serum esRAGE levels. Furthermore, compared to healthy subjects, schizophrenia showed significantly lower esRAGE (p = 0.007) and sRAGE (p = 0.03) levels, respectively. This is the first study to show that serum esRAGE levels are regulated by a newly identified specific haplotype in AGER and that a subpopulation of schizophrenic patients are more vulnerable to carbonyl stress.

Clozapine ameliorates epigenetic and behavioral abnormalities induced by phencyclidine through activation of dopamine D1 receptor.

Accumulating evidence suggests that dysregulation of histone modification is involved in the pathogenesis and/or pathophysiology of psychiatric disorders. However, the abnormalities in histone modification in the animal model of schizophrenia and the efficacy of antipsychotics for such abnormalities remain unclear. Here, we investigated the involvement of histone modification in phencyclidine-induced behavioral abnormalities and the effects of antipsychotics on these abnormalities. After repeated phencyclidine (10 mg/kg) treatment for 14 consecutive days, mice were treated with antipsychotics (clozapine or haloperidol) or the histone deacetylase inhibitor sodium butyrate for 7 d. Repeated phencyclidine treatments induced memory impairment and social deficit in the mice. The acetylation of histone H3 at lysine 9 residues decreased in the prefrontal cortex with phencyclidine treatment, whereas the expression level of histone deacetylase 5 increased. In addition, the phosphorylation of Ca²âº/calmodulin-dependent protein kinase II in the nucleus decreased in the prefrontal cortex of phencyclidine-treated mice. These behavioral and epigenetic changes in phencyclidine-treated mice were attenuated by clozapine and sodium butyrate but not by haloperidol. The dopamine D1 receptor antagonist SCH-23390 blocked the ameliorating effects of clozapine but not of sodium butyrate. Furthermore, clozapine and sodium butyrate attenuated the decrease in expression level of GABAergic system-related genes in the prefrontal cortex of phencyclidine-treated mice. These findings suggest that the antipsychotic effect of clozapine develops, at least in part, through epigenetic modification by activation of the dopamine D1 receptor in the prefrontal cortex.

Deletion of SHATI/NAT8L increases dopamine D1 receptor on the cell surface in the nucleus accumbens, accelerating methamphetamine dependence.

In a previous report, we identified a novel molecule, SHATI/NAT8L, having an inhibitory effect on methamphetamine (METH)-induced hyperlocomotion, sensitization, and conditioned place preference (CPP). SHATI/NAT8L attenuates the METH-induced increase in dopamine overflow in the nucleus accumbens (NAc) by promoting plasmalemmal and vesicular dopamine uptake. However, the biological functions of the protein remain unclear. In this study, we explored NAT8L-binding proteins using pull-down assays and identified a number of components of the adaptor protein (AP)-2 complex, which is a multimeric protein localized to the plasma membrane that functions to internalize cargo during clathrin-mediated endocytosis. To investigate whether NAT8L regulates the receptor localization to the cell surface, cell-surface dopamine D1 receptor in the NAc of Nat8l knockout (KO) mice was quantified. We found that dopamine D1 receptor on the cell surface was increased in the NAc of Nat8l KO mice compared with the wild type (WT) animals. Consistent with this finding, Nat8l KO mice showed higher basal locomotor activity and heightened sensitivity to D1 agonist compared with WT mice. In addition, METH-induced sensitization and CPP were enhanced in Nat8l KO mice. These results suggest that NAT8L might regulate the localization of cell-surface dopamine D1 receptor, thereby controlling basal behaviour and sensitivity to METH. Furthermore, we observed a single nucleotide polymorphism (SNP) in the human NAT8L gene related to reward dependence, a personality trait, and grey matter volume in the caudate nucleus in healthy subjects, suggesting that NAT8L might also affect human personality.

Carbonyl stress and schizophrenia.

Appropriate biological treatment and psychosocial support are essential to achieve and maintain recovery for patients with schizophrenia. Despite extensive efforts to clarify the underlying disease mechanisms, the main cause and pathophysiology of schizophrenia remain unclear. This is due in large part to disease heterogeneity, which results in biochemical differences within a single disease entity. Other factors include variability across clinical symptoms and disease course, along with varied risk factors and treatment responses. Although schizophrenia's positive symptoms are largely managed through treatment with atypical antipsychotics, new classes of drugs are needed to address the unmet medical need for improving cognitive dysfunction and promoting recovery of negative symptoms in these patients. Accumulation of toxic reactive dicarbonyls, such as methylglyoxal, are typical indicators of carbonyl stress, and result in the modification of proteins and the formation of advanced glycation end products, such as pentosidine. In June 2010, we reported on idiopathic carbonyl stress in a subpopulation of schizophrenia patients, leading to a failure of metabolic systems with plasma pentosidine accumulation and serum pyridoxal depletion. Our findings suggest two markers, pentosidine and pyridoxal, as beneficial for distinguishing a specific subgroup of schizophrenics. We believe that this information, derived from in vitro and in vivo studies, is beneficial in the search for personalized and hopefully more effective treatment regimens in schizophrenia. Here, we define a subtype of schizophrenia based on carbonyl stress and the potential for using carbonyl stress as a biomarker in the challenge of overcoming heterogeneity in schizophrenia treatment.

Amyloban, extracted from Hericium erinaceus, ameliorates social deficits and suppresses the enhanced dopaminergic system in social defeat stress mice.

Social dysfunctions are common in various psychiatric disorders, including depression, schizophrenia, and autism, and are long-lasting and difficult to treat. The development of treatments for social impairment is critical for the treatment of several psychiatric disorders. "Amyloban 3399," a product extracted from the mushroom Hericium erinaceus, markedly improves social dysfunctions in patients with treatment-resistant schizophrenia and depression. However, the molecular mechanism(s) through which amyloban ameliorates social impairment remains unclear. To clarify this mechanism, in this study, we aimed to establish a mouse model of social defeat stress (SDS) and investigate the effects of amyloban on social deficits. Amyloban administration ameliorated social deficits and the dopamine system activity in SDS mice. These findings suggest that there is a possibility that amyloban may improve social deficits by suppressing the hyperactivation of the dopaminergic system. Amyloban may be an effective treatment for social dysfunctions associated with various psychiatric disorders.

Association of homocysteine with white matter dysconnectivity in schizophrenia.

Several studies have shown white matter (WM) dysconnectivity in people with schizophrenia (SZ). However, the underlying mechanism remains unclear. We investigated the relationship between plasma homocysteine (Hcy) levels and WM microstructure in people with SZ using diffusion tensor imaging (DTI). Fifty-three people with SZ and 83 healthy controls (HC) were included in this retrospective observational study. Tract-Based Spatial Statistics (TBSS) were used to evaluate group differences in WM microstructure. A significant negative correlation between plasma Hcy levels and WM microstructural disruption was noted in the SZ group (Spearman's ρ = -.330, P = 0.016) but not in the HC group (Spearman's ρ = .041, P = 0.712). These results suggest that increased Hcy may be associated with WM dysconnectivity in SZ, and the interaction between Hcy and WM dysconnectivity could be a potential mechanism of the pathophysiology of SZ. Further, longitudinal studies are required to investigate whether high Hcy levels subsequently cause WM microstructural disruption in people with SZ.

SHATI/NAT8L regulates neurite outgrowth via microtubule stabilization.

We previously identified a new molecule, "SHATI/NAT8L," which has an inhibitory effect on methamphetamine (METH)-induced hyperlocomotion, sensitization, and conditioned place preference. Nevertheless, the extent of SHATI localization and its functions are only partially understood. In this study, we used the FLAG-tag method to investigate SHATI localization. We found that SHATI was localized to microtubules when expressed in COS7 cells and cortical primary neurons. This distribution of SHATI was less apparent after cells were treated with colchicine, a tubulin polymerization inhibitor that disrupts the microtubule structure. This finding suggests that SHATI is associated with microtubule structure. Interestingly, overexpression of SHATI in COS7 cells could attenuate the colchicine-induced decrease in acetylated microtubules, indicating that SHATI plays a role in stabilizing microtubules. Furthermore, we showed that Shati deletion impaired neurite elongation. In cortical primary neurons, neurite length and complexity in Shati-knockout (KO) mice were significantly decreased. In pyramidal neurons in the prefrontal cortex, dendrite length and complexity were also significantly decreased in Shati-KO mice compared with wild-type mice. These results suggest a novel function for SHATI, which may be a new member of the microtubule-associated protein family.

A Cell System-Assisted Strategy for Evaluating the Natural Antioxidant-Induced Double-Stranded DNA Break (DSB) Style.

Natural antioxidants derived from plants exert various physiological effects, including antitumor effects. However, the molecular mechanisms of each natural antioxidant have not yet been fully elucidated. Identifying the targets of natural antioxidants with antitumor properties in vitro is costly and time-consuming, and the results thus obtained may not reliably reflect in vivo conditions. Therefore, to enhance understanding regarding the antitumor effects of natural antioxidants, we focused on DNA, one of the targets of anticancer drugs, and evaluated whether antioxidants, e.g., sulforaphane, resveratrol, quercetin, kaempferol, and genistein, which exert antitumor effects, induce DNA damage using gene-knockout cell lines derived from human Nalm-6 and HeLa cells pretreated with the DNA-dependent protein kinase inhibitor NU7026. Our results suggested that sulforaphane induces single-strand breaks or DNA strand crosslinks and that quercetin induces double-strand breaks. In contrast, resveratrol showed the ability to exert cytotoxic effects other than DNA damage. Our results also suggested that kaempferol and genistein induce DNA damage via unknown mechanisms. Taken together, the use of this evaluation system facilitates the analysis of the cytotoxic mechanisms of natural antioxidants.

Urinary exosomal microRNAs as predictive biomarkers for persistent psychotic-like experiences.

Psychotic-like experiences (PLEs) occur occasionally in adolescence and mostly disappear with increasing age. Their presence, if persistent, is considered a robust risk factor for subsequent psychiatric disorders. To date, only a few biological markers have been investigated for persistent PLE prediction. This study identified urinary exosomal microRNAs that can serve as predictive biomarkers for persistent PLEs. This study was part of a population-based biomarker subsample study of the Tokyo Teen Cohort Study. A total of 345 participants aged 13 (baseline) and 14 (follow-up) years underwent PLE assessments by experienced psychiatrists using semi-structured interviews. We defined remitted and persistent PLEs based on longitudinal profiles. We obtained urine at baseline and the expression levels of urinary exosomal miRNAs were compared between 15 individuals with persistent PLEs and 15 age- and sex-matched individuals with remitted PLEs. We constructed a logistic regression model to examine whether miRNA expression levels could predict persistent PLEs. We identified six significant differentially expressed microRNAs, namely hsa-miR-486-5p, hsa-miR-199a-3p, hsa-miR-144-5p, hsa-miR-451a, hsa-miR-143-3p, and hsa-miR-142-3p. The predictive model showed an area under the curve of 0.860 (95% confidence interval: 0.713-0.993) for five-fold cross-validation. We found a subset of urinary exosomal microRNAs that were differentially expressed in persistent PLEs and presented the likelihood that a microRNA-based statistical model could predict them with high accuracy. Therefore, urine exosomal miRNAs may serve as novel biomarkers for the risk of psychiatric disorders.

Association between enhanced carbonyl stress and decreased apparent axonal density in schizophrenia by multimodal white matter imaging.

Carbonyl stress is a condition featuring increased rich reactive carbonyl compounds, which facilitate the formation of advanced glycation end products including pentosidine. We previously reported the relationship between enhanced carbonyl stress and disrupted white matter integrity in schizophrenia, although which microstructural component is disrupted remained unclear. In this study, 32 patients with schizophrenia (SCZ) and 45 age- and gender-matched healthy volunteers (HC) were recruited. We obtained blood samples for carbonyl stress markers (plasma pentosidine and serum pyridoxal) and multi-modal magnetic resonance imaging measures of white matter microstructures including apparent axonal density (intra-cellular volume fraction (ICVF)) and orientation (orientation dispersion index (ODI)), and inflammation (free water (FW)). In SCZ, the plasma pentosidine level was significantly increased. Group comparison revealed that mean white matter values were decreased for ICVF, and increased for FW. We found a significant negative correlation between the plasma pentosidine level and mean ICVF values in SCZ, and a significant negative correlation between the serum pyridoxal level and mean ODI value in HC, regardless of age. Our results suggest an association between enhanced carbonyl stress and axonal abnormality in SCZ.

Glucuronic acid is a novel source of pentosidine, associated with schizophrenia.

Pentosidine (PEN) is an advanced glycation end-product (AGEs), where a fluorescent cross-link is formed between lysine and arginine residues in proteins. Accumulation of PEN is associated with aging and various diseases. We previously reported that a subpopulation of patients with schizophrenia showed PEN accumulation in the blood, having severe clinical features. PEN is thought to be produced from glucose, fructose, pentoses, or ascorbate. However, patients with schizophrenia with high PEN levels present no elevation of these precursors of PEN in their blood. Therefore, the molecular mechanisms underlying PEN accumulation and the molecular pathogenesis of schizophrenia associated with PEN accumulation remain unclear. Here, we identified glucuronic acid (GlcA) as a novel precursor of PEN from the plasma of subjects with high PEN levels. We demonstrated that PEN can be generated from GlcA, both in vitro and in vivo. Furthermore, we found that GlcA was associated with the diagnosis of schizophrenia. Among patients with high PEN, the proportion of those who also have high GlcA is 25.6%. We also showed that Aldo-keto reductase (AKR) activity to degrade GlcA was decreased in patients with schizophrenia, and its activity was negatively correlated with GlcA levels in the plasma. This is the first report to show that PEN is generated from GlcA. In the future, this finding will contribute to understanding the molecular pathogenesis of not only schizophrenia but also other diseases with PEN accumulation.

GABAergic precursor transplantation into the prefrontal cortex prevents phencyclidine-induced cognitive deficits.

Phencyclidine (PCP) is a noncompetitive NMDA receptor antagonist, and it induces schizophreniform cognitive deficits in healthy humans and similar cognitive deficits in rodents. Although the PCP-induced cognitive deficits appear to be accompanied and possibly caused by dysfunction of GABAergic inhibitory interneurons in the prefrontal cortex (PFC), the potential benefit(s) of GABAergic interneuron manipulations on PCP-induced cognitive deficits remains unexplored. In this study we show that when embryonic medial ganglionic eminence (MGE) cells, many of which differentiate into cortical GABAergic interneurons in situ, were grafted into the medial PFC (mPFC) of neonatal mice, they differentiated into a specific class of GABAergic interneurons and became functionally integrated into the host neuronal circuitry in adults. Prior MGE cell transplantation into the mPFC significantly prevented the induction of cognitive and sensory-motor gating deficits by PCP. The preventive effects were not reproduced by either transplantation of cortical projection neuron precursors into the mPFC or transplantation of MGE cells into the occipital cortex. The preventive effects of MGE cell transplantation into the mPFC were accompanied by activation of callosal projection neurons in the mPFC. These findings suggest that increasing GABAergic interneuron precursors in the PFC may contribute to the development of a cell-based approach as a novel means of modulating the PFC neuronal circuitry and preventing schizophreniform cognitive deficits.

Exposure to enriched environments during adolescence prevents abnormal behaviours associated with histone deacetylation in phencyclidine-treated mice.

Enriched environments (EEs) during development have been shown to influence adult behaviour. Environmental conditions during childhood may contribute to the onset and/or pathology of schizophrenia; however, it remains unclear whether EE might prevent the development of schizophrenia. Herein, we investigated the effects of EE during adolescence on phencyclidine (PCP)-induced abnormal behaviour, a proposed schizophrenic endophenotype. Male ICR mice (3 wk old) were exposed to an EE for 4 wk and then treated with PCP for 2 wk. The EE potentiated the acute PCP treatment-induced hyperlocomotion in the locomotor test and prevented chronic PCP treatment-induced impairments of social behaviour and recognition memory in the social interaction and novel object recognition tests. It also prevented the PCP-induced decrease of acetylated Lys9 in histone H3-positive cells and increase of the histone deacetylase (HDAC)5 level in the prefrontal cortex. To investigate whether the histone modification during adolescence might be critical for the effect of EE, 3-wk-old mice were first treated with sodium butyrate (SB; an HDAC inhibitor) for 4 wk and then treated with PCP for 2 wk. Chronic SB treatment during adolescence mimicked the effects of EE, including potentiation of hyperlocomotion induced by acute PCP treatment and prevention of social and cognitive impairments, decrease of acetylated Lys9 in histone H3-positive cells and increase of the HDAC5 level in the prefrontal cortex associated with chronic PCP treatment. Our results suggest that EEs prevent PCP-induced abnormal behaviour associated with histone deacetylation. EEs during childhood might prove to be a novel strategy for prophylaxis against schizophrenia.

Determination of N-acetylaspartic acid concentration in the mouse brain using HPLC with fluorescence detection.

The concentration of brain N-acetylaspartic acid (NAA) in mice was determined by high-performance liquid chromatography (HPLC) using fluorescence detection after pre-column derivatization with 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benzoxadiazole (DBD-ED). Six different brain parts, namely, the prefrontal cortex, olfactory bulb, nucleus accumbens, striatum, cerebellum and hippocampus, of male C57BL6/J mice, were investigated. The NAA concentration (nmol/mg protein) was highest in the olfactory bulb (58.2 ± 4.0, n = 8) and lowest in the hippocampus (42.8 ± 1.6, n = 8). The proposed HPLC method with fluorescence detection was successfully used to determine the NAA concentration in each investigated brain area.