Apoptotic mechanisms and the synaptic pathology of schizophrenia

FADD adaptor and PEA-15/ERK1/2 partners in major depression and schizophrenia postmortem brains: basal contents and effects of psychotropic treatments

Enhanced brain apoptosis (neurons and glia) may be involved in major depression (MD) and schizophrenia (SZ), mainly through the activation of the intrinsic (mitochondrial) apoptotic pathway. In the extrinsic death pathway, pro-apoptotic Fas-associated death domain (FADD) adaptor and its non-apoptotic p-Ser194 FADD form have critical roles interacting with other death regulators such as phosphoprotein enriched in astrocytes of 15 kDa (PEA-15) and extracellular signal-regulated kinase (ERK). The basal status of FADD (protein and messenger RNA (mRNA)) and the effects of psychotropic drugs (detected in blood/urine samples) were first assessed in postmortem prefrontal cortex of MD and SZ subjects (including a non-MD/SZ suicide group). In MD, p-FADD, but not total FADD (and mRNA), was increased (26%, n=24; all MD subjects) as well as p-FADD/FADD ratio (a pro-survival marker) in antidepressant-free MD subjects (50%, n=10). In contrast, cortical FADD (and mRNA), p-FADD, and p-FADD/FADD were not altered in SZ brains (n=21) regardless of antipsychotic medications (except enhanced mRNA in treated subjects). Similar negative results were quantified in the non-MD/SZ suicide group. In MD, the regulation of multifunctional PEA-15 (i.e., p-Ser116 PEA-15 blocks pro-apoptotic FADD and PEA-15 prevents pro-survival ERK action) and the modulation of p-ERK1/2 were also investigated. Cortical p-PEA-15 was not changed whereas PEA-15 was increased mainly in antidepressant-treated subjects (16-20%). Interestingly, cortical p-ERK1/2/ERK1/2 ratio was reduced (33%) in antidepressant-free when compared to antidepressant-treated MD subjects. The neurochemical adaptations of brain FADD (increased p-FADD and pro-survival p-FADD/FADD ratio), as well as its interaction with PEA-15, could play a major role to counteract the known activation of the mitochondrial apoptotic pathway in MD.

White matter injuries induced by MK-801 in a mouse model of schizophrenia based on NMDA antagonism

The etiology of schizophrenia (SZ) is complex and largely unknown. Neuroimaging and postmortem studies have suggested white matter disturbances in SZ. In the present study, we tested the white matter deficits hypothesis of SZ using a mouse model of SZ induced by NMDA receptor antagonist MK-801. We found that mice with repeated chronic MK-801 administration showed increased locomotor activity in the open field test, less exploration of a novel environment in the hole-board test, and increased anxiety in the elevated plus maze but no impairments were observed in coordination or motor function on accelerating rota-rod. The total white matter volume and corpus callosum volume in mice treated with MK-801 were significantly decreased compared to control mice treated with saline. Myelin basic protein and 2', 3'-cyclic nucleotide 3'-phosphodiesterase were also significantly decreased in the mouse model of SZ. Furthermore, we observed degenerative changes of myelin sheaths in the mouse model of SZ. These results provide further evidence of white matter deficits in SZ and indicate that the animal model of SZ induced by MK-801 is a useful model to investigate mechanisms underlying white matter abnormalities in SZ.

Dietary cyclic dipeptides, apoptosis and psychiatric disorders: a hypothesis

Cyclic dipeptides from food and intestinal yeast cyclic dipeptides may play a role in causing psychiatric disorders such as schizophrenia. From cancer research, cyclic dipeptides such as cyclo (proline-phenylalanine) have been found to activate the pathways of apoptosis and to cause programmed cell death. Activation of such pathways is also thought to be important in causing the neurodevelopmental abnormalities seen in disorders such as schizophrenia and autistic disorder, and also may be important in Alzheimer's. Cyclic dipeptides are found in foods such as malt and cocoa and beer. The intestinal yeast Candida albicans also synthesizes cyclic dipeptides. These dipeptides may be activating apoptosis pathways throughout fetal development and postnatal development, leading to some of the changes seen in brain in schizophrenia and in other psychiatric disorders. These compounds should be researched further to see if they play a role in causing these brain changes. In addition, these cyclic dipeptides are considered within the larger context of research on amino acids and other cyclic dipeptides in neurotransmission and neurophysiology. A better understanding of the role of these cyclic dipeptides in psychiatric disorders could lead to strategies for prevention and treatment of these disorders.

Molecular profiles of pyramidal neurons in the superior temporal cortex in schizophrenia

Disrupted synchronized oscillatory firing of pyramidal neuronal networks in the cerebral cortex in the gamma frequency band (i.e., 30-100 Hz) mediates many of the cognitive deficits and symptoms of schizophrenia. In fact, the density of dendritic spines and the average somal area of pyramidal neurons in layer 3 of the cerebral cortex, which mediate both long-range (associational) and local (intrinsic) corticocortical connections, are decreased in subjects with this illness. To explore the molecular pathophysiology of pyramidal neuronal dysfunction, we extracted ribonucleic acid (RNA) from laser-captured pyramidal neurons from layer 3 of Brodmann's area 42 of the superior temporal gyrus (STG) from postmortem brains from schizophrenia and normal control subjects. We then profiled the messenger RNA (mRNA) expression of these neurons, using microarray technology. We identified 1331 mRNAs that were differentially expressed in schizophrenia, including genes that belong to the transforming growth factor beta (TGF-β) and the bone morphogenetic proteins (BMPs) signaling pathways. Disturbances of these signaling mechanisms may in part contribute to the altered expression of other genes found to be differentially expressed in this study, such as those that regulate extracellular matrix (ECM), apoptosis, and cytoskeletal and synaptic plasticity. In addition, we identified 10 microRNAs (miRNAs) that were differentially expressed in schizophrenia; enrichment analysis of their predicted gene targets revealed signaling pathways and gene networks that were found by microarray to be dysregulated, raising an interesting possibility that dysfunction of pyramidal neurons in schizophrenia may in part be mediated by a concerted dysregulation of gene network functions as a result of the altered expression of a relatively small number of miRNAs. Taken together, findings of this study provide a neurobiological framework within which specific hypotheses about the molecular mechanisms of pyramidal cell dysfunction in schizophrenia can be formulated.

Global association between cortical thinning and white matter integrity reduction in schizophrenia

Previous neuroimaging studies have revealed that both gray matter (GM) and white matter (WM) are altered in several morphological aspects in schizophrenia patients. Although several studies reported associations between GM and WM alterations in restricted regions, the existence of a global association between GM and WM pathologies is unknown. Considering the wide distribution of GM morphological changes and the profound genetic background of WM abnormalities, it would be natural to postulate a global association between pathologies of GM and WM in schizophrenia. In this investigation, we studied 35 schizophrenia patients and 35 healthy control subjects using T1-weighted magnetic resonance imaging and diffusion tensor imaging (DTI) and investigated the association between GM thickness and WM fractional anisotropy (FA) as a proxy of pathology in each tissue. To investigate cortical thickness, surface-based analysis was used. The mean cortical thickness for the whole brain was computed for each hemisphere, and group comparisons were performed. For DTI data, mean FA for the whole brain was calculated, and group comparisons were performed. Subsequently, the correlation between mean cortical thickness and mean FA was investigated. Results showed that the mean cortical thickness was significantly thinner, and the mean FA was significantly lower in schizophrenia patients. Only in the patient group the mean cortical thickness and mean FA showed significant positive correlations in both hemispheres. This correlation remained significant even after controlling for demographic and clinical variables. Thus, our results indicate that the GM and WM pathologies of schizophrenia are intertwined at the global level.

Oxygen glucose deprivation post-conditioning protects cortical neurons against oxygen-glucose deprivation injury: role of HSP70 and inhibition of apoptosis

In the present study, we examined the effect of oxygen glucose deprivation (OGD) post-conditioning (PostC) on neural cell apoptosis in OGD-PostC model and the protective effect on primary cortical neurons against OGD injury in vitro. Four-h OGD was induced by OGD by using a specialized and humidified chamber. To initiate OGD, culture medium was replaced with de-oxygenated and glucose-free extracellular solution-Locke's medium. After OGD treatment for 4 h, cells were then allowed to recover for 6 h or 20 h. Then lactate dehydrogenase (LDH) release assay, Western blotting and flow cytometry were used to detect cell death, protein levels and apoptotic cells, respectively. For the PostC treatment, three cycles of 15-min OGD, followed by 15 min normal cultivation, were applied immediately after injurious 4-h OGD. Cells were then allowed to recover for 6 h or 20 h, and cell death was assessed by LDH release assay. Apoptotic cells were flow cytometrically evaluated after 4-h OGD, followed by re-oxygenation for 20 h (O4/R20). In addition, Western blotting was used to examine the expression of heat-shock protein 70 (HSP70), Bcl-2 and Bax. The ratio of Bcl-2 expression was (0.44±0.08)% and (0.76±0.10)%, and that of Bax expression was (0.51±0.05)% and (0.39±0.04)%, and that of HSP70 was (0.42±0.031)% and (0.72±0.045)% respectively in OGD group and PostC group. After O4/R6, the rate of neuron death in PostC group and OGD groups was (28.96±3.03)% and (37.02±4.47)%, respectively. Therefore, the PostC treatment could up-regulate the expression of HSP70 and Bcl-2, but down-regulate Bax expression. As compared with OGD group, OGD-induced neuron death and apoptosis were significantly decreased in PostC group (P<0.05). These findings suggest that PostC inhibited OGD-induced neuron death. This neuro-protective effect is likely achieved by anti-apoptotic mechanisms and is associated with over-expression of HSP70.

Frontal gamma noise power and cognitive domains in schizophrenia

The cognitive deficit profile is different among individuals with schizophrenia. We quantified the amount of electroencephalographic activity unlocked to stimuli onset (noise power) over frontal regions regarding deficit in cognitive domains. Forty-six patients with schizophrenia and 27 healthy controls underwent clinical, cognitive and electrophysiological assessments. Noise power studies may be considered complementary but not equivalent to induced power studies. We compared gamma and theta noise power magnitude during a P300 paradigm between subsets of patients divided according to cognitive deficit in key domains and controls. Patients displayed higher gamma noise power activity at Fz site and significantly lower performance in all cognitive domains when compared to controls. The subset of patients with cognitive deficit for working memory and problem solving/executive functions domains displayed significantly higher frontal-lateral noise power values in comparison to the subset of patients without cognitive deficit and controls. Patients with significant cognitive deficits in domains with greater frontal contribution are also characterized by an abnormally higher gamma band noise power over the frontal region. Our data may endorse various biological subsets within schizophrenia, characterized by the presence or absence of a significant cognitive deficit in frontal domains.

Profile of minocycline and its potential in the treatment of schizophrenia

Accumulating evidence suggests that neuroinflammation affecting microglia plays an important role in the etiology of schizophrenia, and appropriate control of microglial activation may be a promising therapeutic strategy for schizophrenia. Minocycline, a second-generation tetracycline that inhibits microglial activation, has been shown to have a neuroprotective effect in various models of neurodegenerative disease, including anti-inflammatory, antioxidant, and antiapoptotic properties, and an ability to modulate glutamate-induced excitotoxicity. Given that these mechanisms overlap with neuropathologic pathways, minocycline may have a potential role in the adjuvant treatment of schizophrenia, and improve its negative symptoms. Here, we review the relevant studies of minocycline, ranging from preclinical research to human clinical trials.

Increased susceptibility to apoptosis in cultured fibroblasts from antipsychotic-naïve first-episode schizophrenia patients

Altered apoptosis has been proposed as a potential mechanism involved in the abnormal neurodevelopment and neurodegenerative processes associated with schizophrenia. The aim of this study was to investigate in primary fibroblast cultures whether antipsychotic-naïve patients with first-episode schizophrenia have greater apoptotic susceptibility than healthy controls. Cell growth, cell viability and various apoptotic hallmarks (caspase-3 activity, translocation of phosphatidylserine, chromatin condensation and gene expression of AKT1, BAX, BCL2, CASP3, GSK3B and P53) were measured in fibroblast cultures obtained from skin biopsies of patients (n = 11) and healthy controls (n = 8), both in basal conditions and after inducing apoptosis with staurosporine. Compared to controls, cultured fibroblasts from patients showed higher caspase-3 activity and lower BCL2 expression. When exposed to staurosporine, fibroblasts from patients also showed higher caspase-3 activity; a higher percentage of cells with translocated phosphatidylserine and condensed chromatin; and higher p53 expression compared to fibroblasts from controls. No differences in cell viability or cell growth were detected. These results strongly support the hypothesis that first-episode schizophrenia patients may have increased susceptibility to apoptosis, which may be involved in the onset and progression of the disease.

Bcl-2 associated with positive symptoms of schizophrenic patients in an acute phase

B cell lymphoma protein-2 (Bcl-2) may contribute to the pathophysiology of schizophrenia in the brain. The aim of this study was to investigate the serum levels of Bcl-2 in schizophrenic patients in an acute phase, and evaluate Bcl-2 level changes after antipsychotic treatment. We consecutively enrolled 41 schizophrenia patients in an acute phase; 28 were followed up with a 4-week antipsychotic treatment. Serum Bcl-2 levels were measured with assay kits. All patients were evaluated by examining the correlation between Bcl-2 levels and Positive and Negative Syndrome Scale (PANSS) scores, using Pearson correlation coefficients. In schizophrenic patients in an acute phase, positive PANSS subscores were significantly negatively correlated with Bcl-2 levels. In addition, we found Bcl-2 levels had a significantly negative correlation with PANSS total scores and positive subscores in male patients in an acute phase. Using the paired t-test, we found no significant changes in Bcl-2 levels in schizophrenia patients who had received the 4-week treatment with antipsychotic drugs (n=28). In conclusion, our results suggest that Bcl-2 might be an indicator of schizophrenia severity in the acute phase. In addition, Bcl-2 levels might be associated with positive symptoms in male patients with schizophrenia.

Neurogenic locus notch homolog protein 4 and brain-derived neurotrophic factor variants combined effect on schizophrenia susceptibility

OBJECTIVES

To investigate the relationships between single-nucleotide polymorphisms (SNPs) in NOTCH4 and brain-derived neurotrophic factor (BDNF) with schizophrenia among Han Chinese in Southern China.

METHODS

Two NOTCH4 SNPs (rs520688 and rs415929) and two BDNF SNPs (rs2030324 and rs12273539) were examined in 464 schizophrenics and 464 healthy controls from Hunan province in South China, using the Sequenom MassARRAY® iPLEX System.

RESULTS

In the study population, rs520688 and rs2030324 were significantly associated with schizophrenia. A decreased risk of schizophrenia was associated with the rs520688 GA genotype (p = 0.035), whereas an increased risk of schizophrenia was associated with the rs2030324 CC/CT genotype (p = 0.044). The genotype distributions of rs415929 in NOTCH4 and rs12273539 in BDNF did not differ significantly between the case and control groups. Although no allele-allele interactions were detected between rs520688 and rs2030324, recombination analysis revealed a combined effect of the two on the susceptibility to schizophrenia, with GA-TT decreasing and CT/CC-GG/GA increasing the risk of schizophrenia.

CONCLUSION

In conclusion, rs520688 in NOTCH4 and rs2030324 in BDNF are significantly associated with schizophrenia among Han Chinese in Southern China. The two had a combined effect on the susceptibility to schizophrenia among Han Chinese in Southern China, but this may not be caused by an allele-allele interaction.

Cortical thickness as a contributor to abnormal oscillations in schizophrenia?

Introduction

Although brain rhythms depend on brain structure (e.g., gray and white matter), to our knowledge associations between brain oscillations and structure have not been investigated in healthy controls (HC) or in individuals with schizophrenia (SZ). Observing function–structure relationships, for example establishing an association between brain oscillations (defined in terms of amplitude or phase) and cortical gray matter, might inform models on the origins of psychosis. Given evidence of functional and structural abnormalities in primary/secondary auditory regions in SZ, the present study examined how superior temporal gyrus (STG) structure relates to auditory STG low-frequency and 40 Hz steady-state activity. Given changes in brain activity as a function of age, age-related associations in STG oscillatory activity were also examined.

Methods

Thirty-nine individuals with SZ and 29 HC were recruited. 40 Hz amplitude-modulated tones of 1 s duration were presented. MEG and T1-weighted sMRI data were obtained. Using the sources localizing 40 Hz evoked steady-state activity (300 to 950 ms), left and right STG total power and inter-trial coherence were computed. Time–frequency group differences and associations with STG structure and age were also examined.

Results

Decreased total power and inter-trial coherence in SZ were observed in the left STG for initial post-stimulus low-frequency activity (~ 50 to 200 ms, ~ 4 to 16 Hz) as well as 40 Hz steady-state activity (~ 400 to 1000 ms). Left STG 40 Hz total power and inter-trial coherence were positively associated with left STG cortical thickness in HC, not in SZ. Left STG post-stimulus low-frequency and 40 Hz total power were positively associated with age, again only in controls.

Discussion

Left STG low-frequency and steady-state gamma abnormalities distinguish SZ and HC. Disease-associated damage to STG gray matter in schizophrenia may disrupt the age-related left STG gamma-band function–structure relationships observed in controls.

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Associations between brain oscillations and structure were investigated in SZ

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The present study examined how superior temporal gyrus (STG) structure and agerelate to auditory STG low-frequency and 40 Hz steady-state activity

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Decreased total power and inter-trial coherence in SZ were observed in the left STG for early low-frequency activity (~ 50 to 200 ms, ~ 4 to 16 Hz) as well as 40 Hz steady-state activity (~ 400 to 1000 ms)

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Left STG 40 Hz total power and inter-trial coherence were positively associated with left STG cortical thickness in HC, not in SZ

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Disease-associated damage to STG gray matter in schizophrenia may disrupt the age-related left STG function-structure relationships observed in controls.

Epigenetics and autism

This review identifies mechanisms for altering DNA-histone interactions of cell chromatin to upregulate or downregulate gene expression that could serve as epigenetic targets for therapeutic interventions in autism. DNA methyltransferases (DNMTs) can phosphorylate histone H3 at T6. Aided by protein kinase C β 1, the DNMT lysine-specific demethylase-1 prevents demethylation of H3 at K4. During androgen-receptor-(AR-) dependent gene activation, this sequence may produce AR-dependent gene overactivation which may partly explain the male predominance of autism. AR-dependent gene overactivation in conjunction with a DNMT mechanism for methylating oxytocin receptors could produce high arousal inputs to the amygdala resulting in aberrant socialization, a prime characteristic of autism. Dysregulation of histone methyltransferases and histone deacetylases (HDACs) associated with low activity of methyl CpG binding protein-2 at cytosine-guanine sites in genes may reduce the capacity for condensing chromatin and silencing genes in frontal cortex, a site characterized by decreased cortical interconnectivity in autistic subjects. HDAC1 inhibition can overactivate mRNA transcription, a putative mechanism for the increased number of cerebral cortical columns and local frontal cortex hyperactivity in autistic individuals. These epigenetic mechanisms underlying male predominance, aberrant social interaction, and low functioning frontal cortex may be novel targets for autism prevention and treatment strategies.

A mechanistic approach to preventing schizophrenia in at-risk individuals

In this issue of Neuron, Schobel et al. (2013) report that excess hippocampal glutamate may cause transition to psychosis in individuals at high risk for schizophrenia. Their data has implications for prevention strategies and why stress often precipitates this transition.

Psychosis Following Traumatic Brain Injury

Psychosis following traumatic brain injury (PFTBI) has received modest empirical investigation, and is subsequently poorly understood, identified and treated. The current article reports on consistencies in PFTBI phenomenology according to the existing peer-reviewed literature. The potential for psychotic symptoms post TBI, aetiological propositions, prevalence, significance of onset latency and injury severity, clinical and cognitive neuropsychological presentation and injury localisation/neuroimaging data are reviewed. Substantial methodological limitations associated with the majority of publications informing this work are also discussed. Despite controversies in the literature, psychosis following TBI appears to be three times more prevalent than psychotic disorders in the general population, and comparable in presentation to other idiopathic psychotic spectrum disorders, including schizophrenia.

Neuroinflammation in schizophrenia especially focused on the role of microglia

An accumulating body of evidence point to the significance of neuroinflammation and immunogenetics also in schizophrenia. Recent genome-wide studies in schizophrenia suggest immune involvement in schizophrenia. Microglia are the resident macrophage of the brain and major players in innate immunity in the CNS. They respond rapidly to even minor pathological changes in the brain and may contribute directly to the neuronal degeneration by producing various pro-inflammatory cytokines and free radicals. In many aspects, the neuropathology of schizophrenia is closely associated with microglial activation. We and other researchers have shown the inhibitory effects of some typical or atypical antipsychotics on the release of inflammatory cytokines and free radicals from activated microglia, both of which are not only directly toxic to neurons but also cause a decrease in neurogenesis as well as white matter abnormalities in the brains of the patients with schizophrenia. The treatment through the inhibition of microglial activation may shed new light on the therapeutic strategy of schizophrenia.

Synapsin II gene expression in the dorsolateral prefrontal cortex of brain specimens from patients with schizophrenia and bipolar disorder: effect of lifetime intake of antipsychotic drugs

Synapsins are neuronal phosphoproteins crucial to regulating the processes required for normal neurotransmitter release. Synapsin II, in particular, has been implied as a candidate gene for schizophrenia. This study investigated synapsin II mRNA expression, using Real Time RT-PCR, in coded dorsolateral prefrontal cortical samples provided by the Stanley Foundation Neuropathology Consortium. Synapsin IIa was decreased in patients with schizophrenia when compared to both healthy subjects and patients with bipolar disorder, whereas the synapsin IIb was only significantly reduced in patients with schizophrenia when compared to healthy subjects, but not patients with bipolar disorder. Furthermore, lifetime antipsychotic drug use was positively associated with synapsin IIa expression in patients with schizophrenia. Results suggest that impairment of synaptic transmission by synapsin II reduction may contribute to dysregulated convergent molecular mechanisms which result in aberrant neural circuits that characterize schizophrenia, while implicating involvement of synapsin II in therapeutic mechanisms of currently prescribed antipsychotic drugs.

Are microglia minding us? Digging up the unconscious mind-brain relationship from a neuropsychoanalytic approach

The unconscious mind-brain relationship remains unresolved. From the perspective of neuroscience, neuronal networks including synapses have been dominantly believed to play crucial roles in human mental activities, while glial contribution to mental activities has long been ignored. Recently, it has been suggested that microglia, glial cells with immunological/inflammatory functions, play important roles in psychiatric disorders. Newly revealed microglial roles, such as constant direct contact with synapses even in the normal brain, have defied the common traditional belief that microglia do not contribute to neuronal networks. Recent human neuroeconomic investigations with healthy volunteers using minocycline, an antibiotic with inhibitory effects on microglial activation, suggest that microglia may unconsciously modulate human social behaviors as “noise.” We herein propose a novel unconscious mind structural system in the brain centering on microglia from a neuropsychoanalytic approach. At least to some extent, microglial activation in the brain may activate unconscious drives as “psychological immune memory/reaction” in the mind, and result in various emotions, traumatic reactions, psychiatric symptoms including suicidal behaviors, and (psychoanalytic) transference during interpersonal relationships. Microglia have the potential to bridge the huge gap between neuroscience, biological psychiatry, psychology and psychoanalysis as a key player to connect the conscious and the unconscious world.

Behavioral, neurochemical and morphological changes induced by the overexpression of munc18-1a in brain of mice: relevance to schizophrenia

Overexpression of the mammalian homolog of the unc-18 gene (munc18-1) has been described in the brain of subjects with schizophrenia. Munc18-1 protein is involved in membrane fusion processes, exocytosis and neurotransmitter release. A transgenic mouse strain that overexpresses the protein isoform munc18-1a in the brain was characterized. This animal displays several schizophrenia-related behaviors, supersensitivity to hallucinogenic drugs and deficits in prepulse inhibition that reverse after antipsychotic treatment. Relevant brain areas (that is, cortex and striatum) exhibit reduced expression of dopamine D(1) receptors and dopamine transporters together with enhanced amphetamine-induced in vivo dopamine release. Magnetic resonance imaging demonstrates decreased gray matter volume in the transgenic animal. In conclusion, the mouse overexpressing brain munc18-1a represents a new valid animal model that resembles functional and structural abnormalities in patients with schizophrenia. The animal could provide valuable insights into phenotypic aspects of this psychiatric disorder.

Piperphentonamine (PPTA) attenuated cerebral ischemia-induced memory deficits via neuroprotection associated with anti-apoptotic activity

The calcium sensitizers levosimendan and piperphentonamine hydrochloride (PPTA) are used as cardiovascular drugs for treatment of heart failure. Given that levosimendan has been reported to exhibit a neuroprotective profile in a model of traumatic brain injury, it was interesting to know whether PPTA, a new calcium sensitizer recently developed in China, exerts a similar effect. The objective of this study was to determine whether PPTA exhibited neuroprotective effects and whether these properties were associated with memory. Four-vessel occlusion (4-VO) was used to induce global cerebral ischemia/reperfusion injury in rats treated with or without PPTA (5, 10 mg/kg, i.p., 2 h after the onset of reperfusion and then once a day for 15 consecutive days). Memory was measured using the step-through passive avoidance test. Neurochemical changes were examined in rat PC12 cells treated with oxygen-glucose deprivation (OGD) for 4 h followed by reoxygenation (OGD-R) for 24 h, in the absence or presence of PPTA. In vehicle-treated animals, 4-VO for 10 min produced memory deficits, as demonstrated by decreased retention in step-through passive avoidance, and massive neuron loss in the hippocampal CA1 subregion. These effects were attenuated by PPTA. The results were consistent with those observed in PC12 cells. PPTA treatment increased cell viability, as indicated by MTT assay, inhibited apoptosis, and decreased extracellular lactate dehydrogenase levels in Na(2)S(2)O(4)-treated PC12 cells. These results provide novel demonstration for the ability of PPTA to attenuate cerebral ischemia-induced memory deficits via neuroprotection in the hippocampus. The neuroprotective effect of PPTA appears to be associated with its anti-apoptotic activity. PPTA has the therapeutic potential for ischemic stroke.

A meta-analysis of the polyunsaturated fatty acid composition of erythrocyte membranes in schizophrenia

BACKGROUND

Membrane abnormalities in polyunsaturated fatty acids (PUFAs) have been reported in schizophrenia and have been associated with brain tissue loss in normal ageing. Therefore PUFA may be involved in the excessive brain tissue loss reported in schizophrenia.

METHODS

A systematic MEDLINE database search was conducted to identify studies that compared PUFAs in erythrocyte membranes in patients and controls. Patients were categorized by medication regime in medication naive first-episode patients, and patients receiving typical or atypical antipsychotics.

SAMPLE

Fourteen studies were included, comprising a total of 429 patients with schizophrenia and 444 healthy control subjects. Cohen's d effect sizes were calculated for PUFAs in erythrocyte membranes using the random-effects model. Combined Cohen's d was calculated separately for patients on different medication regime.

RESULTS

Medication-naive patients and patients taking typical antipsychotics showed significantly (p<0.01) decreased concentrations of arachidonic (AA), docosahexaenoic (DHA), and docosapentaenoic (DPA) acid. In addition, patients taking typical antipsychotics showed decreased linoleic (LA), dihomo-γ-linolenic acid (DGLA), eicosapentaenoic (EPA) and docosatetraenoic (DTA) acid (p<0.01). Patients taking atypical antipsychotics showed decreased DHA (p<0.01) only.

CONCLUSIONS

PUFA concentrations in erythrocyte membranes are decreased in schizophrenia. Of particular importance in patients are lower concentrations of DHA and AA, two fatty acids that are abundant in the brain and important precursors in the cell-signalling cascade.

Selective vulnerability of synaptic signaling and metabolism to nitrosative stress

SIGNIFICANCE

Nitric oxide (NO) plays diverse physiological roles in the central nervous system, where it modulates neuronal communication, regulates blood flow, and contributes to the innate immune responses. In a number of brain pathologies, the excessive production of NO also leads to the formation of reactive and toxic intermediates generically termed reactive nitrogen species (RNS). RNS cause irreversible or poorly reversible damage to brain cells.

RECENT ADVANCES

Recent work in the field focused on the ability of NO and RNS to yield protein modifications, including the S-nitrosation of cysteine residues, which, in many instances, impact cellular functions and viability.

CRITICAL ISSUES

The vast majority of neuropathological studies focus on the loss of cell viability, but nitrosative stress may also strongly impair the functions of neuronal processes: axonal projections and dendritic trees. The functional integrity of axons and dendrites critically depends on local metabolism and effective delivery of metabolic enzymes and organelles. Here, we summarize the existing literature describing the effects of nitrosative stress on the major pathways of energetic metabolism: glycolysis, tricarboxylic acid cycle, and mitochondrial respiration, with the emphasis on modifications of protein thiols.

FUTURE DIRECTIONS

We propose that axons and dendrites are highly vulnerable to nitrosative stress because of their low glycolytic capacity and high dependence on timely delivery of metabolic enzymes and organelles from the cell body. Thus, supplementation with the end products of glycolysis, pyruvate or lactate, may help preserve metabolism in distal neuronal processes and protect or restore synaptic function in the ailing brain.

Myelination and oxidative stress alterations in the cerebellum of the G72/G30 transgenic schizophrenia mouse model

G72/G30 is a primate-specific locus that has been repeatedly implicated as a risk factor in genetic studies of schizophrenia. The function of the longest G72 splice variant (LG72 protein) encoded by this locus is not fully understood. To investigate the role of the LG72 protein in vivo, we have generated transgenic (G72Tg) mice carrying the G72/G30 locus that exhibit schizophrenia-like symptoms. We investigated protein expression alterations in the cerebella of G72Tg compared to wild type (WT) mice using a proteomics approach based on in vivo(15)N metabolic labeling and quantitative mass spectrometry (MS). Our data revealed expression level differences of proteins involved in myelin-related processes, oxidative stress and mitochondrial function. Furthermore, in silico pathway analyses suggested common regulators and targets for the observed protein alterations. Our work sheds light on the functional role of the LG72 protein and pinpoints molecular correlates of schizophrenia-like behavior.

Temporal and frontal cortical thickness associations with M100 auditory activity and attention in healthy controls and individuals with schizophrenia

BACKGROUND

Although gray matter (GM) abnormalities are frequently observed in individuals with schizophrenia (SCZ), the functional consequences of these structural abnormalities are not yet understood. The present study sought to better understand GM abnormalities in SCZ by examining associations between GM and two putative functional SCZ biomarkers: weak 100 ms (M100) auditory responses and impairment on tests of attention.

METHODS

Data were available from 103 subjects (healthy controls=52, SCZ=51). GM cortical thickness measures were obtained for superior temporal gyrus (STG) and prefrontal cortex (PFC). Magnetoencephalography (MEG) provided measures of left and right STG M100 source strength. Subjects were administered the Trail Making Test A and the Connors' Continuous Performance Test to assess attention.

RESULTS

A strong trend indicated less GM cortical thickness in SCZ than controls in both regions and in both hemispheres (p=0.06). Individuals with SCZ had weaker M100 responses than controls bilaterally, and individuals with SCZ performed more poorly than controls on tests of attention. Across groups, left STG GM was positively associated with left M00 source strength. In SCZ only, less left and right STG and PFC GM predicted poorer performance on tests of attention. After removing variance in attention associated with age, associations between GM and attention remained significant only in left and right STG.

CONCLUSIONS

Reduced GM cortical thickness may serve as a common substrate for multiple functional abnormalities in SCZ, with structural-functional abnormalities in STG GM especially prominent. As suggested by others, functional abnormalities in SCZ may be a consequence of elimination of the neuropil (dendritic arbors and associated synaptic infrastructure) between neuron bodies.

Possible dysregulation of cortical plasticity in auditory verbal hallucinations-A cortical thickness study in schizophrenia

INTRODUCTION

Investigations of gray matter changes in relation with auditory verbal hallucinations (AVH) have reported conflicting results. Assuming that alterations in gray matter might be related to certain symptoms in schizophrenia this study aimed to investigate changes in cortical thickness specific to AVH. It was hypothesized that schizophrenia patients suffering from persistent AVH would show significant differences in cortical thickness in regions involved in language-production and perception when compared to schizophrenia patients which had never experienced any hallucinations.

METHODS

Using cortical thickness analysis the present study investigated ten schizophrenic patients suffering from AVH, ten non-hallucinating schizophrenic patients, and ten healthy control subjects. Anatomical data were acquired on a 3 T MRI system, transformed into standard space and cortically aligned to investigate local differences in whole brain cortical thickness between the two patient groups. Based on this comparison, brain regions with alterations specific for the patients with AVH were identified and then used as regions of interest to compare both patient groups to the healthy subjects respectively.

RESULTS

Hallucinating patients showed gray matter reductions in the dominant hemisphere predominantly in sensory language areas relevant for speech processing. Increased cortical thickness was found in regions related to self-monitoring.

CONCLUSIONS

Gray matter reductions in chronic schizophrenic patients may be the sequel of synaptic derangement or disease-related deregulation of language circuits. In order to clarify the ambiguous information processing additional demands might be put on cortical structures responsible for self-monitoring processes leading to changes in cortical thickness in the sense of neural plasticity.

Nicotinamide-N-methyltransferase (NNMT) in schizophrenia: genetic association and decreased frontal cortex mRNA levels

Emerging evidence suggests impaired one-carbon metabolism in schizophrenia. Homocysteine is one of the key components of one-carbon metabolism. Elevated plasma homocysteine levels were reported in schizophrenia. A linkage study found that nicotinamide-N-methyltransferase (NNMT), an enzyme involved in one-carbon metabolism, is a determinant of plasma homocysteine levels. In an association study the rs694539 NNMT single nucleotide polymorphism (SNP) was found significantly associated with hyperhomocysteinaemia. Aiming to assess the possible involvement of NNMT in the aetiology of schizophrenia we (1) performed an association study of eight NNMT tagged SNPs in 202 families sharing the same ethnic origin including healthy parents and a schizophrenia proband; (2) assessed NNMT mRNA levels in post-mortem frontal cortex of schizophrenia patients. Genotyping was performed using the ABI SNaPshot and the HRM methods. Individual SNPs and haplotypes were analysed for association using the family-based association test (UNPHASED software). NNMT mRNA levels were measured using RT real-time PCR. In the single SNP analysis, rs694539, previously reported to be associated with hyperhomocysteinaemia, and rs1941404 were significantly associated with schizophrenia (p<0.004 and p=0.033, respectively, following permutation test adjustment). Several haplotypes were also significantly associated with schizophrenia (global p values <0.05 following permutation test adjustment). This is the first study demonstrating an association of NNMT with schizophrenia. Post-mortem frontal cortex NNMT mRNA levels were ~35% lower in schizophrenia patients vs. control subjects. Our study favours the notion that NNMT is involved in the aetiology of schizophrenia.

Is lead exposure in early life an environmental risk factor for Schizophrenia? Neurobiological connections and testable hypotheses

Schizophrenia is a devastating neuropsychiatric disorder of unknown etiology. There is general agreement in the scientific community that schizophrenia is a disorder of neurodevelopmental origin in which both genes and environmental factors come together to produce a schizophrenia phenotype later in life. The challenging questions have been which genes and what environmental factors? Although there is evidence that different chromosome loci and several genes impart susceptibility for schizophrenia; and epidemiological studies point to broad aspects of the environment, only recently there has been an interest in studying gene × environment interactions. Recent evidence of a potential association between prenatal lead (Pb(2+)) exposure and schizophrenia precipitated the search for plausible neurobiological connections. The most promising connection is that in schizophrenia and in developmental Pb(2+) exposure there is strong evidence for hypoactivity of the N-methyl-d-aspartate (NMDA) subtype of excitatory amino acid receptors as an underlying neurobiological mechanism in both conditions. A hypofunction of the NMDA receptor (NMDAR) complex during critical periods of development may alter neurobiological processes that are essential for brain growth and wiring, synaptic plasticity and cognitive and behavioral outcomes associated with schizophrenia. We also describe on-going proof of concept gene-environment interaction studies of early life Pb(2+) exposure in mice expressing the human mutant form of the disrupted in schizophrenia 1 (DISC-1) gene, a gene that is strongly associated with schizophrenia and allied mental disorders.

Converging miRNA functions in diverse brain disorders: a case for miR-124 and miR-126

A growing body of information on the biology of miRNAs has revealed new insight into their roles in normal homeostasis and pathology of disease. miRNAs control all steps of the cellular expression machinery acting through a "single miRNA/multiple targets" or "multiple miRNAs/single target" mechanism. They have profound impact on the regulation of signaling pathways, which govern common and specific functions across different cellular phenotypes. There is increasing evidence that various diseases share similar disturbances in gene expression networks. Since miRNAs have both common and varying effects in different cellular contexts, they might also influence overlapping signaling pathways in different organs and disease entities. Here, we review this concept for two miRNAs highly abundant in the brain, miR-124 and miR-126, and their potential role in diseases of the brain.

Gene expression analysis implicates a death receptor pathway in schizophrenia pathology

An increase in apoptotic events may underlie neuropathology in schizophrenia. By data-mining approaches, we identified significant expression changes in death receptor signaling pathways in the dorsolateral prefrontal cortex (DLPFC) of patients with schizophrenia, particularly implicating the Tumor Necrosis Factor Superfamily member 6 (FAS) receptor and the Tumor Necrosis Factor [ligand] Superfamily member 13 (TNFSF13) in schizophrenia. We sought to confirm and replicate in an independent tissue collection the noted mRNA changes with quantitative real-time RT-PCR. To test for regional and diagnostic specificity, tissue from orbital frontal cortex (OFC) was examined and a bipolar disorder group included. In schizophrenia, we confirmed and replicated significantly increased expression of TNFSF13 mRNA in the DLPFC. Also, a significantly larger proportion of subjects in the schizophrenia group had elevated FAS receptor expression in the DLPFC relative to unaffected controls. These changes were not observed in the bipolar disorder group. In the OFC, there were no significant differences in TNFSF13 or FAS receptor mRNA expression. Decreases in BH3 interacting domain death agonist (BID) mRNA transcript levels were found in the schizophrenia and bipolar disorder groups affecting both the DLPFC and the OFC. We tested if TNFSF13 mRNA expression correlated with neuronal mRNAs in the DLPFC, and found significant negative correlations with interneuron markers, parvalbumin and somatostatin, and a positive correlation with PPP1R9B (spinophilin), but not DLG4 (PSD-95). The expression of TNFSF13 mRNA in DLPFC correlated negatively with tissue pH, but decreasing pH in cultured cells did not cause increased TNFSF13 mRNA nor did exogenous TNFSF13 decrease pH. We concluded that increased TNFSF13 expression may be one of several cell-death cytokine abnormalities that contribute to the observed brain pathology in schizophrenia, and while increased TNFSF13 may be associated with lower brain pH, the change is not necessarily causally related to brain pH.

Caffeine consumption prevents diabetes-induced memory impairment and synaptotoxicity in the hippocampus of NONcZNO10/LTJ mice

Diabetic conditions are associated with modified brain function, namely with cognitive deficits, through largely undetermined processes. More than understanding the underlying mechanism, it is important to devise novel strategies to alleviate diabetes-induced cognitive deficits. Caffeine (a mixed antagonist of adenosine A(1) and A(2A) receptors) emerges as a promising candidate since caffeine consumption reduces the risk of diabetes and effectively prevents memory deficits caused by different noxious stimuli. Thus, we took advantage of a novel animal model of type 2 diabetes to investigate the behavioural, neurochemical and morphological modifications present in the hippocampus and tested if caffeine consumption might prevent these changes. We used a model closely mimicking the human type 2 diabetes condition, NONcNZO10/LtJ mice, which become diabetic at 7-11 months when kept under an 11% fat diet. Caffeine (1 g/l) was applied in the drinking water from 7 months onwards. Diabetic mice displayed a decreased spontaneous alternation in the Y-maze accompanied by a decreased density of nerve terminal markers (synaptophysin, SNAP25), mainly glutamatergic (vesicular glutamate transporters), and increased astrogliosis (GFAP immunoreactivity) compared to their wild type littermates kept under the same diet. Furthermore, diabetic mice displayed up-regulated A(2A) receptors and down-regulated A(1) receptors in the hippocampus. Caffeine consumption restored memory performance and abrogated the diabetes-induced loss of nerve terminals and astrogliosis. These results provide the first evidence that type 2 diabetic mice display a loss of nerve terminal markers and astrogliosis, which is associated with memory impairment; furthermore, caffeine consumption prevents synaptic dysfunction and astrogliosis as well as memory impairment in type 2 diabetes.

Effect of the neuroprotective peptide davunetide (AL-108) on cognition and functional capacity in schizophrenia

BACKGROUND

Cognitive dysfunction is a key predictor of functional disability in schizophrenia. Davunetide (AL-108, NAP) is an intranasally administered peptide currently being developed for treatment of Alzheimer's disease and related disorders. This study investigates effects of davunetide on cognition in schizophrenia.

METHOD

Sixty-three subjects with schizophrenia received davunetide at one of two different doses (5, 30 mg) or placebo for 12 weeks in a multicenter, double-blind, parallel-group randomized clinical trial. The MATRICS Consensus Cognitive Battery (MCCB) assessed cognitive effects. The UCSD Performance-based Skills Assessment (UPSA) and the Schizophrenia Cognition Rating Scale (SCoRS) assessed functional capacity. Subjects continued their current antipsychotic treatment during the trial.

RESULTS

There were no significant differences in MCCB change between davunetide and placebo over the three treatment arms (p=.45). Estimated effect-size (d) values were .34 and .21 favoring the 5 and 30 mg doses vs. placebo, respectively. For UPSA, there was a significant main effect of treatment across study arms (p=.048). Between-group effect size (d) values were.74 and .48, favoring the 5 and 30 mg doses, respectively. No significant effects were observed on the SCoRS or on symptom ratings. No significant side effects or adverse events were observed.

CONCLUSION

Davunetide was well tolerated. Effects of davunetide on MCCB-rated cognition were not significant relative to placebo. In contrast, a significant beneficial effect was detected for the UPSA. Based upon effect-size considerations, sample sizes of at least 45-50 subjects/group would be required to obtain significant effects on both MCCB and UPSA, providing guidance for continued clinical development in schizophrenia.

Is the Gly82Ser polymorphism in the RAGE gene relevant to schizophrenia and the personality trait psychoticism?

BACKGROUND

The receptor for advanced glycation end products (RAGE) is the main receptor for S100B, an astrogial proinflammatory mediator that has been suggested to be involved in the pathophysiology of schizophrenia. To further elucidate the possible relevance of inflammation for mental functions, we investigated a functional polymorphism in the gene coding for RAGE in relation to personality traits and susceptibility to schizophrenia.

METHODS

We studied the Gly82Ser polymorphism (rs2070600, 244G>A) in 2 population-based cohorts of middle-aged participants assessed using the Karolinska Scales of Personality. In addition, we compared genotype frequencies between patients with schizophrenia and controls.

RESULTS

The population-based cohorts included 270 women and 247 men, and the case-control study involved 138 patients with schizophrenia and 258 controls. In the population-based cohorts, 82Ser carriers were found to have significantly higher scores for the psychoticism personality trait comprising the detachment and suspicion subscales. The case-control study revealed that the 82Ser allele was significantly more frequent among patients than controls.

LIMITATIONS

This study was limited by the modest sample size and the use of a self-report measure to assess personality traits.

CONCLUSION

Our findings suggest that the proven relation between certain personality traits and schizophrenia can at least to some extent be explained on a genetic level. Also, the activated S100B-RAGE axis may be an underlying cause, not only a consequence, of the disease.

Proteomic analysis of eccrine sweat: implications for the discovery of schizophrenia biomarker proteins

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and multiple reaction monitoring mass spectrometry (MRM-MS) proteomics analyses were performed on eccrine sweat of healthy controls, and the results were compared with those from individuals diagnosed with schizophrenia (SZ). This is the first large scale study of the sweat proteome. First, we performed LC-MS/MS on pooled SZ samples and pooled control samples for global proteomics analysis. Results revealed a high abundance of diverse proteins and peptides in eccrine sweat. Most of the proteins identified from sweat samples were found to be different than the most abundant proteins from serum, which indicates that eccrine sweat is not simply a plasma transudate and may thereby be a source of unique disease-associated biomolecules. A second independent set of patient and control sweat samples were analyzed by LC-MS/MS and spectral counting to determine qualitative protein differential abundances between the control and disease groups. Differential abundances of selected proteins, initially determined by spectral counting, were verified by MRM-MS analyses. Seventeen proteins showed a differential abundance of approximately 2-fold or greater between the SZ pooled sample and the control pooled sample. This study demonstrates the utility of LC-MS/MS and MRM-MS as a viable strategy for the discovery and verification of potential sweat protein disease biomarkers.

Progressive membrane phospholipid changes in first episode schizophrenia with high field magnetic resonance spectroscopy

Patients with a first episode of schizophrenia generally have increased phospholipid membrane breakdown products within the brain, while findings in chronic patients have been inconsistent. In this study we examine progressive changes in phosphorus membrane metabolites in the same patient group through the early years of schizophrenia in brain regions associated with the disease. Sixteen never-treated and medicated first episode schizophrenic patients were assessed at 10 months and 52 months after diagnosis. Sixteen matched volunteers were assessed at baseline and after 35 months. Phospholipid membrane metabolism was assessed with phosphorous magnetic resonance spectroscopy in the thalamus, cerebellum, hippocampus, anterior/posterior cingulate, prefrontal cortex, parieto-occipital cortex, superior temporal gyrus and temporal pole. At 10 months, glycerophosphocholine was increased in the anterior cingulate in patients as compared to controls. Glycerophosphocholine was decreased in the anterior cingulate and increased in the posterior cingulate and left superior temporal gyrus; glycerophosphoethanolamine was decreased in the left thalamus and increased in the left hippocampus within patients over time. At 52 months, compared to controls phosphocholine was increased in the left thalamus and glycerophosphoethanolamine was increased in the left hippocampus. These results imply a gradual inclusion of brain regions in schizophrenia where an initial increase, followed by a decrease in phospholipid membrane metabolites was observed. This pattern, observed in the early years of schizophrenia, is consistent with excitotoxic neural membrane breakdown in these regions.

Autism and cancer risk

A literature review was conducted on the genetic and developmental bases of autism in relation to genes and pathways associated with cancer risk. Convergent lines of evidence from four types of analysis: (1) recent theoretical studies on the causes of autism, (2) epidemiological studies, (3) genetic analyses linking autism with mutations in tumor suppressor genes and other cancer-associated genes and pathways, and (4) contrasts with schizophrenia, Parkinson's, and Alzheimer's disease indicate that autism may involve altered cancer risk. This evidence should motivate further epidemiological studies, and it provides useful insights into the nature of the genetic, epigenetic, and environmental factors underlying the etiologies of autism, other neurological conditions, and carcinogenesis.

Dystrophic serotonin axons in postmortem brains from young autism patients

Autism causes neuropathological changes in varied anatomical loci. A coherent neural mechanism to explain the spectrum of autistic symptomatology has not been proposed because most anatomical researchers focus on point-to-point functional neural systems (e.g., auditory and social networks) rather than considering global chemical neural systems. Serotonergic neurons have a global innervation pattern. Disorders Research Program, AS073234, Program Project (JW). Their cell bodies are found in the midbrain but they project their axons throughout the neural axis beginning in the fetal brain. This global system is implicated in autism by animal models and by biochemical, imaging, pharmacological, and genetics studies. However, no anatomical studies of the 5-HT innervation of autistic donors have been reported. Our review presents immunocytochemical evidence of an increase in 5-HT axons in postmortem brain tissue from autism donors aged 2.8-29 years relative to controls. This increase is observed in the principle ascending fiber bundles of the medial and lateral forebrain bundles, and in the innervation density of the amygdala and the piriform, superior temporal, and parahippocampal cortices. In autistic donors 8 years of age and up, several types of dystrophic 5-HT axons were seen in the termination fields. One class of these dystrophic axons, the thick heavily stained axons, was not seen in the brains of patients with neurodegenerative diseases. These findings provide morphological evidence for the involvement of serotonin neurons in the early etiology of autism, and suggest new therapies may be effective to blunt serotonin's trophic actions during early brain development in children.

Association of genetic variants on 15q12 with cortical thickness and cognition in schizophrenia

CONTEXT

Cortical thickness is a highly heritable structural brain measurement, and reduced thickness has been associated with schizophrenia, bipolar disorder, and decreased cognitive performance among healthy control individuals. Identifying genes that contribute to variation in cortical thickness provides a means to elucidate some of the biological mechanisms underlying these diseases and general cognitive abilities.

OBJECTIVES

To identify common genetic variants that affect cortical thickness in patients with schizophrenia, patients with bipolar disorder, and controls and to test these variants for association with cognitive performance.

DESIGN

A total of 597 198 single-nucleotide polymorphisms were tested for association with average cortical thickness in a genome-wide association study. Significantly associated single-nucleotide polymorphisms were tested for their effect on several measures of cognitive performance.

SETTING

Four major hospitals in Oslo, Norway.

PARTICIPANTS

A total of 1054 case individuals and controls were analyzed in the genome-wide association study and follow-up cognitive study. The genome-wide association study included controls (n = 181) and individuals with DSM-IV -diagnosed schizophrenia spectrum disorder (n = 94), bipolar spectrum disorder (n = 97), and other psychotic and affective disorders (n = 49).

MAIN OUTCOME MEASURES

Cortical thickness measured with magnetic resonance imaging and cognitive performance as assessed by several neuropsychological tests.

RESULTS

Two closely linked genetic variants (rs4906844 and rs11633924) within the Prader-Willi and Angelman syndrome region on chromosome 15q12 showed a genome-wide significant association (P = 1.1 x 10(-8) with average cortical thickness and modest association with cognitive performance (permuted P = .03) specifically among patients diagnosed as having schizophrenia.

CONCLUSION

This genome-wide association study identifies a common genetic variant that contributes to the heritable reduction of cortical thickness in schizophrenia. These results highlight the usefulness of cortical thickness as an intermediate phenotype for neuropsychiatric diseases. Future independent replication studies are required to confirm these findings.

Lack of progression of brain abnormalities in first-episode psychosis: a longitudinal magnetic resonance imaging study

BACKGROUND

Some neuroimaging studies have supported the hypothesis of progressive brain changes after a first episode of psychosis. We aimed to determine whether (i) first-episode psychosis patients would exhibit more pronounced brain volumetric changes than controls over time and (ii) illness course/treatment would relate to those changes.

METHOD

Longitudinal regional grey matter volume and ventricle:brain ratio differences between 39 patients with first-episode psychosis (including schizophrenia and schizophreniform disorder) and 52 non-psychotic controls enrolled in a population-based case-control study.

RESULTS

While there was no longitudinal difference in ventricle:brain ratios between first-episode psychosis subjects and controls, patients exhibited grey matter volume changes, indicating a reversible course in the superior temporal cortex and hippocampus compared with controls. A remitting course was related to reversal of baseline temporal grey matter deficits.

CONCLUSIONS

Our findings do not support the hypothesis of brain changes indicating a progressive course in the initial phase of psychosis. Rather, some brain volume abnormalities may be reversible, possibly associated with a better illness course.

The complement control-related genes CSMD1 and CSMD2 associate to schizophrenia

BACKGROUND

Patients with schizophrenia often suffer from cognitive dysfunction, including impaired learning and memory. We recently demonstrated that long-term potentiation in rat hippocampus, a mechanistic model of learning and memory, is linked to gene expression changes in immunity-related processes involved in complement activity and antigen presentation. We therefore aimed to examine whether key regulators of these processes are genetic susceptibility factors in schizophrenia.

METHODS

Analysis of genetic association was based on data mining of genotypes from a German genome-wide association study and a multiplex GoldenGate tag single nucleotide polymorphism (SNP)-based assay of Norwegian and Danish case-control samples (Scandinavian Collaboration on Psychiatric Etiology), including 1133 patients with schizophrenia and 2444 healthy control subjects.

RESULTS

Allelic associations were found across all three samples for eight common SNPs in the complement control-related gene CSMD2 (CUB and Sushi Multiple Domains 2) on chromosome 1p35.1-34.3, of which rs911213 reached a statistical significance comparable to that of a genome wide threshold (p value = 4.0 × 10(-8); odd ratio = .73, 95% confidence interval = .65-.82). The second most significant gene was CSMD1 on chromosome 8p23.2, a homologue to CSMD2. In addition, we observed replicated associations in the complement surface receptor CD46 as well as the major histocompatibility complex genes HLA-DMB and HLA-DOA.

CONCLUSIONS

These data demonstrate a significant role of complement control-related genes in the etiology of schizophrenia and support disease mechanisms that involve the activity of immunity-related pathways in the brain.

Aripiprazole inhibits superoxide generation from phorbol-myristate-acetate (PMA)-stimulated microglia in vitro: implication for antioxidative psychotropic actions via microglia

Altered antioxidant status has been implicated in schizophrenia. Microglia, major sources of free radicals such as superoxide (•O(2)(-)), play crucial roles in various brain pathologies. Recent postmortem and imaging studies have indicated microglial activation in the brain of schizophrenic patients. We previously demonstrated that atypical antipsychotics including aripiprazole significantly inhibited the release of nitric oxide and proinflammatory cytokines from interferon-γ-stimulated microglia in vitro. Antioxidative effects of antipsychotics via modulating microglial superoxide generation have never been reported. Therefore, we herein investigated the effects of antipsychotics on the •O(2)(-) generation from phorbol-myristate-acetate (PMA)-stimulated rodent microglia by the electron spin resonance (ESR) spectroscopy and also examined the intracellular mechanism by intracellular Ca(2+) imaging and immunostaining. Neuronal damage induced by microglial activation was also investigated by the co-culture experiment. Among various antipsychotics, only aripiprazole inhibited the •O(2)(-) generation from PMA-stimulated microglia. Aripiprazole proved to inhibit the •O(2)(-) generation through the cascade of protein kinase C (PKC) activation, intracellular Ca(2+) regulation and NADPH oxidase activation via cytosolic p47(phox) translocation to the plasma/phagosomal membranes. Formation of neuritic beading, induced by PMA-stimulated microglia, was attenuated by pretreatment of aripiprazole. D2R antagonism has long been considered as the primary therapeutic action for schizophrenia. Aripiprazole with D2R partial agonism is effective like other antipsychotics with fewer side effects, while aripiprazole's therapeutic mechanism itself remains unclear. Our results imply that aripiprazole may have psychotropic effects by reducing the microglial oxidative reactions and following neuronal reactions, which puts forward a novel therapeutic hypothesis in schizophrenia research.

Developmental GABAergic deficit enhances methamphetamine-induced apoptosis

RATIONALE

Neuroanatomical evidence suggests that GABAergic deficits and progressive cortical atrophy occur with schizophrenia.

OBJECTIVE

To evaluate the hypothesis that neurodevelopmental deficits affect neurodegeneration occurring with schizophrenia, this study examined a novel animal model for schizophrenia-related neurodevelopmental GABAergic deficit in neurodegenerative progression.

METHODS

The prenatal N-methyl-D-aspartate (NMDA) receptor hypofunction model that induces neurodevelopmental GABAergic deficit in the medial prefrontal cortex (mPFC) was used to examine whether adult offspring of Sprague-Dawley rats exhibited disruption of prepulse inhibition (PPI), enhancement of methamphetamine (METH) (2.5 mg/kg)-induced glutamate release in the mPFC and the emergence of terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)-positive neurons in this brain region.

RESULTS

Offspring of dams exposed to NMDA receptor antagonist MK-801 on days 15-18 of pregnancy (MK-801 offspring) showed reduced density of parvalbumin-immunoreactive GABAergic interneurons in the mPFC, PPI disruption on postnatal days 63 (P63) and 35 (P35) and an enhanced METH (2.5 mg/kg)-induced glutamate release. Repeated administration of this psychostimulant increased the emergence of TUNEL-positive cells.

CONCLUSION

These findings suggest that prenatal blockade of NMDA receptors induces a neurodevelopmental GABAergic deficit. The decrease in the density of GABAergic neurons might be related to disruption of sensorimotor gating (PPI), enhanced METH-induced release of glutamate in the mPFC and a repeated METH injection-induced increase in apoptosis in this region of the brain in adult animals.

Hemispheric comparisons of neuron density in the planum temporale of schizophrenia and nonpsychiatric brains

Postmortem and in vivo studies of schizophrenia frequently reveal reduced cortical volume, but the underlying cellular abnormalities are incompletely defined. One influential hypothesis, especially investigated in Brodmann's area 9 of prefrontal cortex, is that the number of neurons is normal, and the volume change is caused by reduction of the surrounding neuropil. However, studies have differed on whether the cortex has the increased neuron density that is predicted by this hypothesis. In a recent study of bilateral planum temporale (PT), we reported smaller volume and width of the outer cortex (layers I-III), especially in the left hemisphere, among subjects with schizophrenia. In the present study, we measured neuron density and size in the same PT samples, and also in prefrontal area 9 of the same brains. In the PT, separate stereological measurements were made in layers II, IIIc, and VI, whereas area 9 was sampled in layer IIIb-c. In both cortical regions, there was no significant effect of schizophrenia on neuronal density or size. There was, nevertheless, a trend-level right>left hemispheric asymmetry of neuron density in the PT, which may partially explain the previously reported left>right asymmetry of cortical width. In schizophrenia, our findings suggest that closer packing of neurons may not always explain reduced cortical volume, and subtly decreased neuron number may be a contributing factor.

Mathematical modelling of the mitochondrial apoptosis pathway

Mitochondria are pivotal for cellular bioenergetics, but are also a core component of the cell death machinery. Hypothesis-driven research approaches have greatly advanced our understanding of the role of mitochondria in cell death and cell survival, but traditionally focus on a single gene or specific signalling pathway at a time. Predictions originating from these approaches become limited when signalling pathways show increased complexity and invariably include redundancies, feedback loops, anisotropies or compartmentalisation. By introducing methods from theoretical chemistry, control theory, and biophysics, computational models have provided new quantitative insights into cell decision processes and have led to an increased understanding of the key regulatory principles of apoptosis. In this review, we describe the currently applied modelling approaches, discuss the suitability of different modelling techniques, and evaluate their contribution to the understanding of the mitochondrial apoptosis pathway. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.

Impairment of the tyrosine hydroxylase neuronal network in the orbitofrontal cortex of a genetically modified mouse model of schizophrenia

Important genes have been identified that are associated with susceptibility to schizophrenia. DISC1 is one of these candidate genes. The protein 14-3-3 epsilon is a DISC1-interacting molecule and is associated with axon elongation. The genetically modified 14-3-3 epsilon heterozygous knockout mice are considered to be an animal model of schizophrenia because they present endophenotypes of schizophrenia including working memory impairment. This study investigated the immunohistochemical expression of tyrosine hydroxylase (TH) to reveal the alterations in the functional structure of the axon elongation caused by the deficit of 14-3-3 epsilon. The study focused on the orbitofrontal cortex in the prefrontal cortex which is a region of interest in schizophrenia research. The investigation used eight 15-week-old knockout mice and six age-matched wild-type mice. The TH immunopositive fibers were linear and dense in the wild-type mice. These fibers were serpentine, thin and short in the knockout mice. Although it appeared that dendritic spine-like immunopositive varices were strung tightly in the fibers of wild-type mice, these were few and sparse in those of the of the knockout mice. Quantitative analysis showed a significant decrease in the total extent of the TH-immunopositive fibers in the orbital cortex of the knockout mouse. There is thought to be a dysfunction of a neurotransmitter such as dopamine and noradrenalin in the prefrontal cortex of these knockout mice.