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Despite extensive study of the neurobiological correlates of post-traumatic stress disorder (PTSD), little is known about its molecular determinants. Here, differential gene expression and network analyses of four prefrontal cortex subregions from postmortem tissue of people with PTSD demonstrate extensive remodeling of the transcriptomic landscape. A highly connected downregulated set of interneuron transcripts is present in the most significant gene network associated with PTSD. Integration of this dataset with genotype data from the largest PTSD genome-wide association study identified the interneuron synaptic gene ELFN1 as conferring significant genetic liability for PTSD. We also identified marked transcriptomic sexual dimorphism that could contribute to higher rates of PTSD in women. Comparison with a matched major depressive disorder cohort revealed significant divergence between the molecular profiles of individuals with PTSD and major depressive disorder despite their high comorbidity. Our analysis provides convergent systems-level evidence of genomic networks within the prefrontal cortex that contribute to the pathophysiology of PTSD in humans.

Importance: Primary open-angle glaucoma presents with increased prevalence and a higher degree of clinical severity in populations of African ancestry compared with European or Asian ancestry. Despite this, individuals of African ancestry remain understudied in genomic research for blinding disorders.Objectives: To perform a genome-wide association study (GWAS) of African ancestry populations and evaluate potential mechanisms of pathogenesis for loci associated with primary open-angle glaucoma.Design, Settings, and Participants: A 2-stage GWAS with a discovery data set of 2320 individuals with primary open-angle glaucoma and 2121 control individuals without primary open-angle glaucoma. The validation stage included an additional 6937 affected individuals and 14 917 unaffected individuals using multicenter clinic- and population-based participant recruitment approaches. Study participants were recruited from Ghana, Nigeria, South Africa, the United States, Tanzania, Britain, Cameroon, Saudi Arabia, Brazil, the Democratic Republic of the Congo, Morocco, Peru, and Mali from 2003 to 2018. Individuals with primary open-angle glaucoma had open iridocorneal angles and displayed glaucomatous optic neuropathy with visual field defects. Elevated intraocular pressure was not included in the case definition. Control individuals had no elevated intraocular pressure and no signs of glaucoma.Exposures: Genetic variants associated with primary open-angle glaucoma.Main Outcomes and Measures: Presence of primary open-angle glaucoma. Genome-wide significance was defined as P < 5 × 10−8 in the discovery stage and in the meta-analysis of combined discovery and validation data.Results: A total of 2320 individuals with primary open-angle glaucoma (mean [interquartile range] age, 64.6 [56-74] years; 1055 [45.5%] women) and 2121 individuals without primary open-angle glaucoma (mean [interquartile range] age, 63.4 [55-71] years; 1025 [48.3%] women) were included in the discovery GWAS. The GWAS discovery meta-analysis demonstrated association of variants at amyloid-β A4 precursor protein-binding family B member 2 (APBB2; chromosome 4, rs59892895T>C) with primary open-angle glaucoma (odds ratio [OR], 1.32 [95% CI, 1.20-1.46]; P = 2 × 10−8). The association was validated in an analysis of an additional 6937 affected individuals and 14 917 unaffected individuals (OR, 1.15 [95% CI, 1.09-1.21]; P < .001). Each copy of the rs59892895*C risk allele was associated with increased risk of primary open-angle glaucoma when all data were included in a meta-analysis (OR, 1.19 [95% CI, 1.14-1.25]; P = 4 × 10−13). The rs59892895*C risk allele was present at appreciable frequency only in African ancestry populations. In contrast, the rs59892895*C risk allele had a frequency of less than 0.1% in individuals of European or Asian ancestry.Conclusions and Relevance: In this genome-wide association study, variants at the APBB2 locus demonstrated differential association with primary open-angle glaucoma by ancestry. If validated in additional populations this finding may have implications for risk assessment and therapeutic strategies.

Posttraumatic stress disorder (PTSD) affects approximately 8% of the general population, with higher rates in extreme stress groups, including combat veterans or victims of sexual assault. Despite extensive study of the neurobiological correlates of PTSD, little is known about its molecular substrates. Here differential gene expression and network analyses of 4 prefrontal cortex (PFC) postmortem subregions of male and female PTSD subjects demonstrates extensive remodeling of the transcriptomic landscape. The data revealed a highly connected down-regulated set of interneuron transcripts in the most significant gene network associated with PTSD and integration of this data with genotype data from the largest PTSD GWAS identified the interneuron synaptic gene ELFN1 as conferring significant genetic liability for PTSD. We also identified marked sexual dimorphism in the transcriptomic signatures that could contribute to the higher rates of PTSD in women. Comparison with a matched major depressive disorder (MDD) cohort revealed significant divergence between the molecular profiles of subjects with PTSD and depression despite their high comorbidity. Our analysis provides convergent systems-level evidence of genomic networks within the PFC that contribute to the pathophysiology of PTSD in humans.

Symptoms of posttraumatic stress disorder include hyperarousal, avoidance of trauma-related stimuli, re-experiencing of trauma, and mood changes. This review focuses on the frontal cortical areas that form crucial links in circuitry pertinent to posttraumatic stress disorder symptomatology: (1) the conditioned fear extinction circuit, (2) the salience circuit, and (3) the mood circuit. These frontal areas include the ventromedial prefrontal cortex (conditioned fear extinction), the dorsal anterior cingulate and insular cortices (salience), and the lateral orbitofrontal and subgenual cingulate cortices (mood). Frontal lobe structural abnormalities in posttraumatic stress disorder, including volumetric reductions in the cingulate cortices, impact all three circuits. Functional analyses of frontal cortices in posttraumatic stress disorder show abnormal activation in all three according to task demand and emotional valence. Network analyses reveal altered amygdalo-frontal connectivity and failure to suppress the default mode network during cognitive engagement. Spine shape alterations also have been detected in the medial orbitofrontal cortex in posttraumatic stress disorder postmortem brains, suggesting reduced synaptic plasticity. Importantly, frontal lobe abnormalities in posttraumatic stress disorder extend beyond emotion-related circuits to include the lateral prefrontal cortices that mediate executive functions. In conclusion, widespread frontal lobe dysfunction in posttraumatic stress disorder provides a neurobiologic basis for the core symptomatology of the disorder, as well as for executive function impairment.

As discussion of stress and stress-related disorders rapidly extends beyond the brain, gut microbiota have emerged as a promising contributor to individual differences in the risk of illness, disease course, and treatment response. Here, we employed chronic mild social defeat stress and 16S rRNA gene metagenomic sequencing to investigate the role of microbial composition in mediating anxiety- and depressive-like behavior. In socially defeated animals, we found significant reductions in the overall diversity and relative abundances of numerous bacterial genera, including Akkermansia spp., that positively correlated with behavioral metrics of both anxiety and depression. Functional analyses predicted a reduced frequency of signaling molecule pathways, including G-protein-coupled receptors, in defeated animals. Collectively, our data suggest that shifts in microbial composition may play a role in the pathogenesis of anxiety and depression.

Background We recently assessed blood-based miRNA expression profiles for association with age in a cohort of 895 Mexican Americans. Of 2,747 miRNAs that were tested (including SNP-derived and novel miRNAs in addition to those reported in miRBase 21), we identified significant associations for 46 known miRNAs (p Methods We conducted in vivo studies to test for correlations between blood and brain miR-34a-5p expression across seven brain regions in four baboons. Then, to investigate the consequences of increased miRNA expression on gene expression, we transfected four neuronal and glial cell lines (CHP-212, HCN-2, SVG-P12 and A172) with a miR-34a-5p mimic. We performed functional annotation of genes that were at least 2-fold up- or down-regulated in each of the cell lines using DAVID. Results Our in vivo studies using baboons as a model organism show moderate to strong correlation of miR-34a-5p expression across blood and amygdala (r=0.69), dorsal anterior cingulate cortex (r=0.95), hypothalamus (r=0.77), lateral orbitofrontal cortex (r=0.81) and medial orbitofrontal cortex (0.56), further strengthening its potential role in neuropsychiatric disease. Our in vitro studies identified several functional categories and gene ontologies that were consistent across two or more cell lines, including phosphoprotein, alternative splicing, protein binding and cell cycle. Discussion Through a combination of in vivo, in vitro and in silico studies, we strengthen the argument for miR-34a-5p as an important player in neuropsychiatric research. Our findings suggest important downstream consequences of induced overexpression of miR-34a-5p. We are currently trying to develop a novel unbiased in vitro method to detect miRNA-mRNA binding interactions that would be broadly applicable to any cell type using miR-34a-5p as a model.

Background Given the inaccessibility of brain tissue for large cohort-based and longitudinal studies, analysis of peripheral blood as a surrogate tissue has become a mainstay within the neuropsychiatric field for analysis of gene and miRNA expression and DNA methylation. Although the importance of peripheral biomarkers as diagnostic and prognostic indicators is well recognized, translation of findings into meaningful pathology is more difficult to achieve. Lack of validation of peripheral biomarkers in brain tissue may be confounded by smaller sample sizes, investigation of inappropriate brain regions, or post-mortem complications. Methods To shed some light on the utility of blood-based biomarkers to inform upon pathology of disease, we investigated correlations between miRNA expression levels in blood and brain tissue from 14 cortical and subcortical regions within two groups of baboons (n=4, n=6; 7 brain regions each). To better understand how blood-brain correlations might relate to human biology and disease, we investigated a subset of 212 miRNAs whose peripheral blood expression was at least moderately correlated (r≥0.5) with 50% or more of the brain regions examined in a family-based cohort of Mexican Americans (n=896) for whom we have extensive neurocognitive and neuroanatomical phenotypes as well as peripheral blood miRNA profiles. We tested 145 human peripheral blood-expressed miRNAs for association against 34 cortical and 10 subcortical structures (using magnetic resonance imaging data), and 24 neurocognitive phenotypes. Due to high inter-relatedness and potentially unknown correlations across many of the phenotypes assessed, we corrected only for the number of miRNAs tested, setting the significance threshold at p Results The overall correlation (r) of miRNA expression profiles between blood and 14 different brain regions in baboons ranged from 0.62–0.66. We identified 444 miRNAs that were expressed in 90% of all samples analyzed and of these, 212 showed at least moderate correlation (r≥0.5) between blood and 50% or more of the brain regions examined. Within this subset of baboon-defined correlated miRNAs, we identified 145 that were also expressed in at least 90% of our human cohort and tested these for association with neurological traits. We identified 34 significant associations between miRNAs and neurological traits. Of these, one of the most interesting findings was association of peripheral miR-144-3p expression with amygdala (p=8.50×10-5) and hippocampus (p=5.86×10-5) volumes, as well as thickness of the fusiform gyrus (p=1.98×10-5). In our baboon study, peripheral expression of this miRNA was highly correlated with expression in the amygdala (r=1.00) and hippocampus (r=0.66), expression was not measured in the fusiform gyrus. Discussion Prior studies have shown that overexpression of miR-144-3p in the basolateral amygdala of mice rescued impaired fear extinction, and also that expression of miR-144-3p is increased in the hippocampus of rats following chronic treatment of both lithium and valproate mood stabilizers. Our studies highlight the utility of using peripheral blood as a surrogate tissue for miRNA profiling and indicate that disease associations identified using peripheral blood may point toward pathological processes within the brain, particularly for miRNAs whose expression is correlated between blood and brain.

β-Site APP-cleaving Enzyme 1 (BACE1) is an endopeptidase responsible for proteolytic processing of several proteins including amyloid-precursor protein (APP) and neuregulin 1 (NRG1), a promising schizophrenia candidate gene (Petryshen et al. 2005; Stefansson et al. 2003a,b; Walss-Bass et al. 2006; Williams et al. 2003; Yang et al. 2003; Zhao et al. 2004). BACE1 cleaves NRG1 at the extracellular site, liberating the NRG1 N-terminal domain for interaction with ErbB tyrosine-kinase receptors and activation of downstream signaling events. BACE1 knockout mice (BACE1−/−) show an increase in full-length NRG1, reflecting lack of protein cleavage. These animals exhibit behaviors similar to mice with impaired NRG1 function, including impaired prepulse inhibition and novelty-induced hyperactivity (Luo et al. 2014; Savonenko et al. 2008; Willem et al. 2009), that are considered rodent analogs of schizophrenia behavior in humans. BACE1−/− furthermore exhibit morphological characteristics resembling those found in schizophrenia, including hypomyelination, decreased CA1 spine density and neuronal number, all of which are potentially consequences of altered NRG1-ErbB4 signaling (Hu et al. 2006). Importantly, genetic variants within BACE1 have been shown to correlate significantly with variants within other genes in the NRG1-ErbB4 signaling pathway in schizophrenia families (Hatzimanolis et al. 2013). At the cellular level, enhanced striatal dopamine (DA) release from the terminals of midbrain DA neurons may underlie the positive symptoms of schizophrenia, i.e. hallucinations and delusions (Howes et al. 2012; Lyon et al. 2011). Previous studies have observed functional impairment of the prefrontal striatonigral circuit characterized by task-evoked hyperactivity of the substantia nigra in schizophrenia patients (Yoon et al. 2013). Terminal DA release from midbrain DA neurons is inhibited by D2 DA autoreceptors that are located on their cell bodies, dendrites and axon terminals. In the midbrain, somatodendritic DA release from neighboring DA neurons activates D2 autoreceptors and induces a potassium conductance that inhibits firing frequency (Lacey et al. 1987; Pucak & Grace 1994). Synaptic depression of D2 autoreceptor function can attenuate firing inhibition and thus increases excitability (Beckstead & Williams 2007), which could contribute to midbrain hyperdopaminergia in schizophrenia. Local perfusion with NRG1 stimulates DA release in the hippocampus (Kwon et al. 2008), and intra-striatal injection of NRG1 evokes an almost immediate overflow of striatal DA (Yurek et al. 2004). However, little is known about how disruption of BACE1-mediated cleavage of NRG1 affects midbrain DA signaling and related behaviors. In light of the previous studies showing NRG1 stimulation of DA release, we hypothesized that because of impaired NRG1 cleavage, mice with a BACE1 deletion would exhibit a diminished behavioral response to amphetamine, an indirect DA agonist, with concurrent alterations in DA neuron excitability. In agreement with our hypothesis, we show that BACE1−/− mice exhibit a decrease in sensitivity to the locomotor activation produced by amphetamine. Striatal levels of DA and DA metabolites were unaltered in these mice. Substantia nigra DA neurons from BACE1−/− exhibited enhanced amphetamine-induced D2 autoreceptor-mediated currents and basal firing rate. The increased autoreceptor-mediated inhibition provides a plausible mechanism to explain the decreased sensitivity to amphetamine-induced locomotion in BACE1−/− mice.

Aims The enzyme catechol-O-methyl transferase (COMT) plays a primary role in the metabolism of catecholamine neurotransmitters and is implicated in the modulation of cognitive and emotional responses. The best-characterized single nucleotide polymorphism (SNP) of the COMT gene consists of a valine (Val)-to-methionine (Met) substitution at codon 108/158. The Met-containing variant confers a marked reduction in COMT catalytic activity. We recently showed that the activity of recombinant COMT is positively regulated by the enzyme Met sulfoxide reductase (MSR), which counters the oxidation of Met residues of proteins. The current study was designed to assess whether brain COMT activity may be correlated to MSR in an allele-dependent fashion.

SNAP-25 is a neurotransmitter vesicular docking protein which has been associated with brain disorders such as attention deficit hyperactivity disorder, bipolar disorder and schizophrenia. In this project, we were interested if clinical factors are associated with differential SNAP-25 expression. We examined the SNAP-25 isoform mRNA and protein levels in postmortem cortex Brodmann's area 9 (BA9) and BA24 (n = 29). Subjects were divided by psychiatric diagnosis, clinical variables including mood state in the last week of life and lifetime impulsiveness. We found affected subjects with a diagnosis of alcohol use disorder (AUD) had a lower level of SNAP-25b BA24 protein compared to those without AUD. Hispanic subjects had lower levels of SNAP-25a, b and BA9 mRNA than Anglo-American subjects. Subjects who smoked had a total pan (total) SNAP-25 BA9/BA24 ratio. Subjects in the group with a low level of anxious-psychotic symptoms had higher SNAP-25a BA24 mRNA compared to normal controls, and both the high and low symptoms groups had higher pan (total) SNAP-25 BA9/BA24 ratios than normal controls. These data expand our understanding of clinical factors associated with SNAP-25. They suggest that SNAP-25 total and isoform levels may be useful biomarkers beyond limited neurological and psychiatric diagnostic categories.

Circadian abnormalities may be related to mood disorders. Circadian gene expression was measured in postmortem brain tissue from individuals with affective disorders and controls. Relationships between circadian gene expression, clinical characteristics, and alcohol and psychotropic medication use were noted. Further study is warranted to characterize these relationships.

Venlafaxine (VEN) and its metabolite O-desmethylvenlafaxine (ODV) inhibit reuptake of serotonin and norepinephrine. This study examines whether VEN is differentially distributed in postmortem brain and examines relationships between brain and femoral blood concentrations from donors prescribed VEN for treatment of depression. Using high-pressure liquid chromatography-ultraviolet detection, VEN and ODV concentrations were measured in temporal, occipital, and cerebellar cortex of six postmortem brains. The ODV/VEN ratio was calculated as a relative measure of drug metabolism within each region where higher ratios indicated a greater conversion of VEN to ODV. Compared to the other regions examined, the cerebellum showed decreased VEN (p = 0.056), ODV (p = 0.006), and ODV/VEN (p = 0.027) ratios. In parts per million, VEN was higher in temporal and occipital cortex, but not cerebellum, as compared to femoral blood concentration. These observations suggest that VEN and ODV are differentially distributed in the brain, and metabolism of VEN to ODV may vary across brain regions.

Thompson PM, Cruz DA, Olukotun DY, Delgado PL. Serotonin receptor, SERT mRNA and correlations with symptoms in males with alcohol dependence and suicide. Objective: This study tested the hypothesis that abnormalities in components of the serotonin (5HT) system in the prefrontal cortex are associated with suicide in alcohol-dependent subjects. Second, we assessed the relationship of lifetime impulsivity and mood symptoms with prefrontal cortex 5-HT measures. Method: Tissue was obtained from Brodmann’s areas (BA) 9 and 24 in postmortem samples of individuals who were alcohol dependent with suicide (n = 5), alcohol dependent without suicide (n = 9) and normal controls (n = 5). Serotonin receptor (5HT) and serotonin reuptake transporter (SERT) mRNA were measured. Interviews with next of kin estimated lifetime impulsivity and mood symptoms in the last week of life. Results: Serotonin receptor 1A (5HT1A) mRNA in BA 9 was elevated in the alcohol dependence without suicide group compared with controls. In the alcohol dependence with suicide group, anxiety symptoms were associated with decreased BA 24 SERT mRNA and depressive symptoms with BA 9 5HT1A mRNA expression. In the alcohol dependent only group impulsivity is correlated with increased BA 9, and BA 24 serotonin receptor 2A mRNA. Conclusion: Our data suggest region-specific change, rather than global serotonin blunting is involved in alcohol dependence and suicide. It also suggests that symptoms are differentially influenced by prefrontal cortex serotonin receptor mRNA levels.

We are colonized by a vast population of genetically diverse microbes, the majority of which are unculturable bacteria that reside within the gastrointestinal tract. As affordable, advanced next-generation sequencing technologies become more widely available, important discoveries about the composition and function of these microbes become increasingly possible. In addition to rapid advancement in sequencing technologies, automated systems have been developed for nucleic acid extraction; however, these methods have yet to be widely used for the isolation of bacterial DNA from fecal samples. Here, we adapted Promega’s Maxwell® RSC PureFood GMO and Authentication kit for use with fecal samples and compared it to the commonly used Qiagen QIAamp® PowerFecal® kit. Results showed that the two approaches yielded similar measures of DNA purity and successful next-generation sequencing amplification and produced comparable composition of microbial communities. However, DNA extraction with the Maxwell® RSC kit produced higher concentrations with a lower fecal sample input weight and took a fraction of the time compared to the QIAamp® PowerFecal® protocol. The results of this study demonstrate that the Promega Maxwell® RSC system can be used for medium-throughput DNA extraction in a time-efficient manner without compromising the quality of the downstream sequencing.

Markers of GABA neurotransmission between chandelier neurons and their synaptic targets, the axon initial segment (AIS) of pyramidal neurons, are altered in the dorsolateral prefrontal cortex (dlPFC) of subjects with schizophrenia. For example, immunoreactivity for the GABA membrane transporter (GAT1) is decreased in presynaptic chandelier neuron axon terminals, whereas immunoreactivity for the GABA(A) receptor alpha2 subunit is increased in postsynaptic AIS. To understand the nature and functional significance of these alterations, we determined the density, laminar distribution, and length of AIS immunoreactive (IR) for ankryin-G and betaIV spectrin, two proteins involved in the regulation of synapse structure and ion channel clustering at AIS, in dlPFC area 46 from 14 matched triads of subjects with schizophrenia or major depressive disorder (MDD) and normal comparison participants. The density of ankyrin-G-IR AIS in the superficial, but not in the deep, cortical layers was significantly decreased by 15-19% in the subjects with schizophrenia relative to the other participant groups. In contrast, no group differences were present in the density of betaIV spectrin-IR AIS. The length of labeled AIS did not differ across participant groups for either ankyrin-G or betaIV spectrin. The density of ankyrin-G-IR AIS was not altered in the dlPFC of macaque monkeys chronically exposed to antipsychotic medications. Given the important role of ankyrin-G in the recruitment and stabilization of sodium channels and other integral membrane proteins to AIS, our findings suggest that these processes are selectively altered in superficial layer pyramidal neurons in subjects with schizophrenia.

The enzyme catechol-O-methyltransferase (COMT) plays a primary role in the metabolism of catecholamine neurotransmitters and is implicated in the modulation of cognitive and emotional responses. The best characterized single nucleotide polymorphism (SNP) of the COMT gene consists of a valine (Val)-to-methionine (Met) substitution at codon 108/158. The Met-containing variant confers a marked reduction in COMT catalytic activity. We recently showed that the activity of recombinant COMT is positively regulated by the enzyme Met sulphoxide reductase (MSR), which counters the oxidation of Met residues of proteins. The current study was designed to assess whether brain COMT activity may be correlated to MSR in an allele-dependent fashion.COMT and MSR activities were measured from post-mortem samples of prefrontal cortices, striata and cerebella of 32 subjects by using catechol and dabsyl-Met sulphoxide as substrates, respectively. Allelic discrimination of COMT Val(108/185) Met SNP was performed using the Taqman 5'nuclease assay.Our studies revealed that, in homozygous carriers of Met, but not Val alleles, the activity of COMT and MSR was significantly correlated throughout all tested brain regions.These results suggest that the reduced enzymatic activity of Met-containing COMT may be secondary to Met sulphoxidation and point to MSR as a key molecular determinant for the modulation of COMT activity.

Inhibition mediated by gamma-aminobutyric acid at the axon initial segment of pyramidal neurons appears to be altered in the prefrontal cortex in schizophrenia. This study examined the densities and laminar distribution of axon initial segments labeled with an antibody against the serotonin(1A) (5-HT(1A)) receptor, which also mediates inhibitory regulation of pyramidal neurons, in subjects with schizophrenia.The densities and laminar distribution of axon initial segments with 5-HT(1A)-like immunoreactivity were assessed in postmortem tissue from the prefrontal cortex (Brodmann's area 46) of 14 matched triads of subjects with schizophrenia, subjects with major depressive disorder, and comparison subjects with no psychiatric disorder.The relative densities of the labeled axon initial segment in both the superficial and the deep cortical layers did not differ across the three subject groups.The findings do not support a role for altered serotonin transmission by means of the 5-HT(1A) receptor in dysfunction of prefrontal cortex pyramidal neurons in schizophrenia.

Catechol-O-methyl transferase (COMT) plays a key role in the degradation of brain dopamine (DA). Specifically, low COMT activity results in higher DA levels in the prefrontal cortex (PFC), thereby reducing the vulnerability for attentional and cognitive deficits in both psychotic and healthy individuals. COMT activity is markedly reduced by a non-synonymous single-nucleotide polymorphism (SNP) that generates a valine-to-methionine substitution on the residue 108/158, by means of as-yet incompletely understood post-translational mechanisms. One post-translational modification is methionine sulfoxide, which can be reduced by the methionine sulfoxide reductase (Msr) A and B enzymes. We used recombinant COMT proteins (Val/Met108) and mice (wild-type (WT) and MsrA knockout) to determine the effect of methionine oxidation on COMT activity and COMT interaction with Msr, through a combination of enzymatic activity and Western blot assays. Recombinant COMT activity is positively regulated by MsrA, especially under oxidative conditions, whereas brains of MsrA knockout mice exhibited lower COMT activity (as compared with their WT counterparts). These results suggest that COMT activity may be reduced by methionine oxidation, and point to Msr as a key molecular determinant for the modulation of COMT activity in the brain. The role of Msr in modulating cognitive functions in healthy individuals and schizophrenia patients is yet to be determined.

Background Neuregulin 1 (NRG1) is a key candidate susceptibility gene for both schizophrenia (SCZ) and bipolar disorder (BPD). The function of the NRG1 transmembrane proteins is regulated by cleavage. Alteration of membrane bound-NRG1 cleavage has been previously shown to be associated with behavioral impairments in mouse models lacking expression of NRG1-cleavage enzymes such as BACE1 and gamma secretase. We sought to determine whether alterations in NRG1 cleavage and associated enzymes occur in patients with SCZ and BPD. Methodology/Principal Findings Using human postmortem brain, we evaluated protein expression of NRG1 cleavage products and enzymes that cleave at the external (BACE1, ADAM17, ADAM19) and internal (PS1-gamma secretase) sides of the cell membrane. We used three different cohorts (Controls, SCZ and BPD) and two distinct brain regions: BA9-prefrontal cortex (Controls (n = 6), SCZ (n = 6) and BPD (n = 6)) and hippocampus (Controls (n = 5), SCZ (n = 6) and BPD (n = 6)). In BA9, the ratio of the NRG1 N-terminal fragment relative to full length was significantly upregulated in the SCZ cohort (Bonferroni test, p = 0.011). ADAM17 was negatively correlated with full length NRG1 levels in the SCZ cohort (r = –0.926, p = 0.008). In the hippocampus we found significantly lower levels of a soluble 50 kDa NRG1 fragment in the two affected groups compared the control cohort (Bonferroni test, p = 0.0018). We also examined the relationship of specific symptomatology criteria with measures of NRG1 cleavage using the Bipolar Inventory of Signs and Symptoms Scale (BISS) and the Montgomery Asberg Depression Rating Scale (MADRS). Our results showed a positive correlation between ADAM19 and psychosis (r = 0.595 p = 0.019); PS1 and mania (r = 0.535, p = 0.040); PS1 and depression (r = 0.567, p = 0.027) in BA9, and BACE1 with anxiety (r = 0.608, p = 0.03) in the hippocampus. Conclusion/Significance Our preliminary findings suggest region-specific alterations in NRG1 cleavage in SCZ and BPD patients. These changes may be associated with specific symptoms in these psychiatric disorders.

In the primate prefrontal cortex (PFC), the functional maturation of the synaptic connections of certain classes of gamma-aminobutyric acid (GABA) neurons is very complex. For example, the levels of both pre- and postsynaptic proteins that regulate GABA neurotransmission from the chandelier class of cortical interneurons to the axon initial segment (AIS) of pyramidal neurons undergo marked changes during both the perinatal period and adolescence in the monkey PFC. In order to understand the potential molecular mechanisms associated with these developmental refinements, we quantified the relative densities, laminar distributions, and lengths of pyramidal neuron AIS immunoreactive for ankyrin-G, betaIV spectrin, or gephyrin, three proteins involved in regulating synapse structure and receptor localization, in the PFC of rhesus monkeys ranging in age from birth through adulthood. Ankyrin-G- and betaIV spectrin-labeled AIS declined in density and length during the first 6 postnatal months, but then remained stable through adolescence and into adulthood. In contrast, the density of gephyrin-labeled AIS was stable until approximately 15 months of age and then markedly declined during adolescence. Thus, molecular determinants of the structural features that define GABA inputs to pyramidal neuron AIS in monkey PFC undergo distinct developmental trajectories with different types of changes occurring during the perinatal period and adolescence. In concert with previous data, these findings reveal a two-phase developmental process of GABAergic synaptic stability and GABA neurotransmission at chandelier cell inputs to pyramidal neurons that likely contributes to the protracted maturation of behaviors mediated by primate PFC circuitry.

The typical appearance of the clinical features of schizophrenia during late adolescence or early adulthood suggests that adolescence-related neurodevelopmental events may contribute to the pathophysiology of this disorder. Here the role that GABA-mediated inhibition in the dorsal lateral prefrontal cortex (DLPFC) plays in regulating working memory, a core cognitive process that matures late and that is disturbed in schizophrenia, is reviewed. Recent studies are summarized that demonstrate (1) that certain pre- and postsynaptic markers of GABA neurotransmission in the monkey DLPFC exhibit striking changes during adolescence, and (2) that these same markers are markedly altered in the DLPFC of subjects with schizophrenia. The implications of these findings for treatment and prevention strategies are discussed.

The protracted postnatal maturation of the primate prefrontal cortex (PFC) is associated with substantial changes in the number of excitatory synapses on pyramidal neurons, whereas the total number of inhibitory synapses appears to remain constant. In this study, we sought to determine whether the developmental changes in excitatory input to pyramidal cells are paralleled by changes in functional markers of inhibitory inputs to pyramidal neurons. The chandelier subclass of gamma-aminobutyric acid (GABA) neurons provides potent inhibitory control over pyramidal neurons by virtue of their axon terminals, which form distinct vertical structures (termed cartridges) that synapse at the axon initial segment (AIS) of pyramidal neurons. Thus, we examined the relative densities, laminar distributions, and lengths of presynaptic chandelier axon cartridges immunoreactive for the GABA membrane transporter 1 (GAT1) or the calcium-binding protein parvalbumin (PV) and of postsynaptic pyramidal neuron AIS immunoreactive for the GABA(A) receptor alpha(2) subunit (GABA(A) alpha(2)) in PFC area 46 of 38 rhesus monkeys (Macaca mulatta). From birth through 2 years of age, the relative densities and laminar distributions of these three markers exhibited different trajectories, suggesting developmental shifts in the weighting of at least some factors that determine inhibition at the AIS. In contrast, from 2 to 4 years of age, all three markers exhibited similar declines in density and length that paralleled the periadolescent pruning of excitatory synapses to pyramidal neurons. Across development, the predominant laminar location of PV-labeled cartridges and GABA(A) alpha(2)-immunoreactive AIS shifted from the middle to superficial layers, whereas the laminar distribution of GAT1-positive cartridges did not change. Together, these findings suggest that the maturation of inhibitory inputs to the AIS of PFC pyramidal neurons is a complex process that may differentially affect the firing patterns of subpopulations of pyramidal neurons at specific postnatal time points.

Extensive changes in DNA methylation have been observed in schizophrenia (SC) and bipolar disorder (BP), and may contribute to the pathogenesis of these disorders. Here, we performed genome-scale DNA methylation profiling using methylated DNA immunoprecipitation followed by sequencing (MeDIP-seq) on two brain regions (including frontal cortex and anterior cingulate) in 5 SC, 7 BP and 6 normal subjects. Comparing with normal controls, we identified substantial differentially methylated regions (DMRs) in these two brain regions of SC and BP. To our surprise, different brain regions show completely distinct distributions of DMRs across the genomes. In frontal cortex of both SC and BP subjects, we observed widespread hypomethylation as compared to normal controls, preferentially targeting the terminal ends of the chromosomes. In contrast, in anterior cingulate, both SC and BP subjects displayed extensive gain of methylation. Notably, in these two brain regions of SC and BP, only a few DMRs overlapped with promoters, whereas a greater proportion occurs in introns and intergenic regions. Functional enrichment analysis indicated that important psychiatric disorder-related biological processes such as neuron development, differentiation and projection may be altered by epigenetic changes located in the intronic regions. Transcriptome analysis revealed consistent dysfunctional processes with those determined by DMRs. Furthermore, DMRs in the same brain regions from SC and BP could successfully distinguish BP and/or SC from normal controls while differentially expressed genes could not. Overall, our results support a major role for brain-region-dependent aberrant DNA methylation in the pathogenesis of these two disorders.

Neuronal number in the mediodorsal thalamic nucleus, the principal source of thalamic projections to the prefrontal cortex, has been reported to be lower in subjects with schizophrenia. The authors tested the hypothesis that schizophrenia is associated with a selective deficit in a marker of thalamic axon terminals in the middle layers of the prefrontal cortex, the primary zone of termination of thalamic axons.The densities of parvalbumin-immunoreactive varicosities (putative axon terminals) were determined in the superficial and middle layers of prefrontal cortex area 9 from 20 matched pairs of subjects with schizophrenia and normal comparison subjects. In order to determine the specificity of these observations, similar studies were conducted in subjects with major depressive disorder and in monkeys after 9-12 months of haloperidol treatment.The relative densities of parvalbumin-immunoreactive varicosities did not differ between schizophrenic and comparison subjects in the superficial layers. However, in the middle layers, mean varicosity density was significantly lower (24% difference) in the subjects with schizophrenia. In contrast, neither subjects with major depressive disorder nor haloperidol-treated monkeys exhibited a middle-layer density of parvalbumin-immunoreactive varicosities that was lower than that of their matched comparison groups.Although not definitive, these findings are consistent with the hypothesis of fewer projections from the mediodorsal thalamic nucleus to the prefrontal cortex in schizophrenic subjects and thus converge with other lines of evidence demonstrating an abnormality in thalamo-prefrontal cortical circuitry in persons with schizophrenia.

Investigators are interested in determining whether lifetime behavioral traits and specific mood states experienced close to death affect brain gene and protein expression as assessed in post-mortem human brains. Major obstacles to conducting this type of research are the uncertain reliability of the post-mortem psychiatric diagnoses and clinical information because of the retrospective nature of the information. In this study, we addressed the concordance of clinical information obtained through an informant compared with information obtained through a clinician interview of the subject. To test this, we measured both lifetime and within the week psychiatric symptoms of subjects (n=20) and an informant, their next-of-kin (n=20) who were asked identical questions. We found Diagnostic and Statistical Manual (DSM)-IV axis 1 diagnoses by Mini-International Neuropsychiatric Interview proportion of positive agreement for major depression was 0.97, bipolar disorder was 0.81, whereas proportion of negative agreement was 0.97 for schizophrenia. Symptom scale intra-class correlation coefficients and 95% confidence interval were: Bipolar Inventory of Signs and Symptoms=0.59 (0.23, 0.81), Brief Psychiatric Rating Scale=0.58 (0.19, 0.81), Hamilton Depression Rating Scale=0.44 (0.03, 0.72), Montgomery Asberg Depression Rating Scale=0.44 (0.03, 0.72), Young Mania Rating Scale=0.61 (0.30, 0.82), Barratt Impulsiveness Score=0.36 (-0.11, 0.70) and Childhood Trauma Questionnaire=0.48 (-0.15, 0.83). We show that DSM-IV diagnoses; lifetime impulsivity severity, childhood trauma score and symptom scores were significantly consistent between the subjects and their informants. These data suggest, with some limitations, that both retrospective and informant obtained information can provide useful clinical information in post-mortem research.