Altered thalamic membrane phospholipids in schizophrenia: a postmortem study

From Molecules to the Clinic: Linking Schizophrenia and Metabolic Syndrome through Sphingolipids Metabolism

Metabolic syndrome (MS) is a prevalent and severe comorbidity observed in schizophrenia (SZ). The exact nature of this association is controversial and very often accredited to the effects of psychotropic medications and disease-induced life-style modifications, such as inactive lifestyle, poor dietary choices, and smoking. However, drug therapy and disease-induced lifestyle factors are likely not the only factors contributing to the observed converging nature of these conditions, since an increased prevalence of MS is also observed in first episode and drug-naïve psychosis populations. MS and SZ share common intrinsic susceptibility factors and etiopathogenic mechanisms, which may change the way we approach clinical management of SZ patients. Among the most relevant common pathogenic pathways of SZ and MS are alterations in the sphingolipids (SLs) metabolism and SLs homeostasis. SLs have important structural functions as they participate in the formation of membrane “lipid rafts.” SLs also play physiological roles in cell differentiation, proliferation, and inflammatory processes, which might be part of MS/SZ common pathophysiological processes. In this article we review a plausible mechanism to explain the link between MS and SZ through a disruption in SL homeostasis. Additionally, we provide insights on how this hypothesis can lead to the developing of new diagnostic/therapeutic technologies for SZ patients.

Ultrastructural alterations of oligodendrocytes in prefrontal white matter in schizophrenia: A post-mortem morphometric study

OBJECTIVE

Neuroimaging studies showed abnormalities in frontal white matter (WM) in schizophrenia that were associated with clinical symptoms. Previously, we reported ultrastructural alterations of myelinated fibers and reduction in the numerical density of oligodendrocytes in BA 10 WM in patients with schizophrenia. We aimed to perform a qualitative and morphometric study of the ultrastructure of oligodendrocytes in BA 10 WM in schizophrenia and in normal controls.

METHODS

The study was performed using electron microscopy and morphometry. Size, volume density (Vv) and the number (N) of organelles of oligodendrocytes were estimated in 21 patients with schizophrenia and 20 normal controls. The data were examined using the Kolmogorov-Smirnov test for normality. Pearson correlation analysis was performed to assess possible correlations between the parameters measured and age, post-mortem interval, neuroleptic treatment and duration of the disease. Comparisons between the schizophrenia patients and controls were performed using ANCOVA tests.

RESULTS

We found oligodendrocyte swelling, vacuolation, paucity of ribosomes and mitochondria and accumulation of lipofuscin granules in schizophrenia as compared to controls. Morphometry detected a significant reduction in Vv and N of mitochondria and the increase in Vv and N of lipofuscin granules and vacuoles in oligodendrocytes in the schizophrenic group as compared to controls.

CONCLUSION

Alterations of oligodendrocytes in schizophrenia provide evidence for the disturbance of their energy, lipid and protein metabolism in prefrontal WM. Oligodendrocyte abnormalities might disturb axonal integrity and circuitry and contribute to the pathophysiology of schizophrenia.

Membrane lipidomics in schizophrenia patients: a correlational study with clinical and cognitive manifestations

Schizophrenia is a severe mental condition in which several lipid abnormalities-either structural or metabolic-have been described. We tested the hypothesis that an abnormality in membrane lipid composition may contribute to aberrant dopamine signaling, and thereby symptoms and cognitive impairment, in schizophrenia (SCZ) patients. Antipsychotic-medicated and clinically stable SCZ outpatients (n=74) were compared with matched healthy subjects (HC, n=40). A lipidomic analysis was performed in red blood cell (RBC) membranes examining the major phospholipid (PL) classes and their associated fatty acids (FAs). Clinical manifestations were examined using the positive and negative syndrome scale (PANSS). Cognitive function was assessed using the Continuous Performance Test, Salience Attribution Test and Wisconsin Card Sorting Test. Sphingomyelin (SM) percentage was the lipid abnormality most robustly associated with a schizophrenia diagnosis. Two groups of patients were defined. The first group (SCZ c/SM-) is characterized by a low SM membrane content. In this group, all other PL classes, plasmalogen and key polyunsaturated FAs known to be involved in brain function, were significantly modified, identifying a very specific membrane lipid cluster. The second patient group (SCZ c/SM+) was similar to HCs in terms of RBC membrane SM composition. Compared with SCZ c/SM+, SCZ c/SM- patients were characterized by significantly more severe PANSS total, positive, disorganized/cognitive and excited psychopathology. Cognitive performance was also significantly poorer in this subgroup. These data show that a specific RBC membrane lipid cluster is associated with clinical and cognitive manifestations of dopamine dysfunction in schizophrenia patients. We speculate that this membrane lipid abnormality influences presynaptic dopamine signaling.

Single-neuron and genetic correlates of autistic behavior in macaque

Atypical neurodevelopment in autism spectrum disorder is a mystery, defying explanation despite increasing attention. We report on a Japanese macaque that spontaneously exhibited autistic traits, namely, impaired social ability as well as restricted and repetitive behaviors, along with our single-neuron and genomic analyses. Its social ability was measured in a turn-taking task, where two monkeys monitor each other's actions for adaptive behavioral planning. In its brain, the medial frontal neurons responding to others' actions, abundant in the controls, were almost nonexistent. In its genes, whole-exome sequencing and copy number variation analyses identified rare coding variants linked to human neuropsychiatric disorders in 5-hydroxytryptamine (serotonin) receptor 2C (HTR2C) and adenosine triphosphate (ATP)-binding cassette subfamily A13 (ABCA13). This combination of systems neuroscience and cognitive genomics in macaques suggests a new, phenotype-to-genotype approach to studying mental disorders.

Regulation of sphingomyelin metabolism

Sphingolipids (SFs) represent a large class of lipids playing diverse functions in a vast number of physiological and pathological processes. Sphingomyelin (SM) is the most abundant SF in the cell, with ubiquitous distribution within mammalian tissues, and particularly high levels in the Central Nervous System (CNS). SM is an essential element of plasma membrane (PM) and its levels are crucial for the cell function. SM content in a cell is strictly regulated by the enzymes of SM metabolic pathways, which activities create a balance between SM synthesis and degradation. The de novo synthesis via SM synthases (SMSs) in the last step of the multi-stage process is the most important pathway of SM formation in a cell. The SM hydrolysis by sphingomyelinases (SMases) increases the concentration of ceramide (Cer), a bioactive molecule, which is involved in cellular proliferation, growth and apoptosis. By controlling the levels of SM and Cer, SMSs and SMases maintain cellular homeostasis. Enzymes of SM cycle exhibit unique properties and diverse tissue distribution. Disturbances in their activities were observed in many CNS pathologies. This review characterizes the physiological roles of SM and enzymes controlling SM levels as well as their involvement in selected pathologies of the Central Nervous System, such as ischemia/hypoxia, Alzheimer disease (AD), Parkinson disease (PD), depression, schizophrenia and Niemann Pick disease (NPD).

A decade from discovery to therapy: Lingo-1, the dark horse in neurological and psychiatric disorders

Leucine-rich repeat and immunoglobulin domain-containing protein (Lingo-1) is a potent negative regulator of neuron and oligodendrocyte survival, neurite extension, axon regeneration, oligodendrocyte differentiation, axonal myelination and functional recovery; all processes highly implicated in numerous brain-related functions. Although playing a major role in developmental brain functions, the potential application of Lingo-1 as a therapeutic target for the treatment of neurological disorders has so far been under-estimated. A number of preclinical studies have shown that various methods of antagonizing Lingo-1 results in neuronal and oligodendroglial survival, axonal growth and remyelination; however to date literature has only detailed applications of Lingo-1 targeted therapeutics with a focus primarily on myelination disorders such as multiple sclerosis and spinal cord injury; omitting important information regarding Lingo-1 signaling co-factors. Here, we provide for the first time a complete and thorough review of the implications of Lingo-1 signaling in a wide range of neurological and psychiatric disorders, and critically examine its potential as a novel therapeutic target for these disorders.

Glial cells as key players in schizophrenia pathology: recent insights and concepts of therapy

The past decade has witnessed an explosion of knowledge on the impact of glia for the neurobiological foundation of schizophrenia. A plethora of studies have shown structural and functional abnormalities in all three types of glial cells. There is convincing evidence of reduced numbers of oligodendrocytes, impaired cell maturation and altered gene expression of myelin/oligodendrocyte-related genes that may in part explain white matter abnormalities and disturbed inter- and intra-hemispheric connectivity, which are characteristic signs of schizophrenia. Earlier reports of astrogliosis could not be confirmed by later studies, although the expression of a variety of astrocyte-related genes is abnormal in psychosis. Since astrocytes play a key role in the synaptic metabolism of glutamate, GABA, monoamines and purines, astrocyte dysfunction may contribute to certain aspects of disturbed neurotransmission in schizophrenia. Finally, increased densities of microglial cells and aberrant expression of microglia-related surface markers in schizophrenia suggest that immunological/inflammatory factors are of considerable relevance for the pathophysiology of psychosis. This review describes current evidence for the multifaceted role of glial cells in schizophrenia and discusses efforts to develop glia-directed therapies for the treatment of the disease.

Clozapine promotes glycolysis and myelin lipid synthesis in cultured oligodendrocytes

Clozapine displays stronger systemic metabolic side effects than haloperidol and it has been hypothesized that therapeutic antipsychotic and adverse metabolic effects of these drugs are related. Considering that cerebral disconnectivity through oligodendrocyte dysfunction has been implicated in schizophrenia, it is important to determine the effect of these drugs on oligodendrocyte energy metabolism and myelin lipid production. Effects of clozapine and haloperidol on glucose and myelin lipid metabolism were evaluated and compared in cultured OLN-93 oligodendrocytes. First, glycolytic activity was assessed by measurement of extra- and intracellular glucose and lactate levels. Next, the expression of glucose (GLUT) and monocarboxylate (MCT) transporters was determined after 6 and 24 h. And finally mitochondrial respiration, acetyl-CoA carboxylase, free fatty acids, and expression of the myelin lipid galactocerebroside were analyzed. Both drugs altered oligodendrocyte glucose metabolism, but in opposite directions. Clozapine improved the glucose uptake, production and release of lactate, without altering GLUT and MCT. In contrast, haloperidol led to higher extracellular levels of glucose and lower levels of lactate, suggesting reduced glycolysis. Antipsychotics did not alter significantly the number of functionally intact mitochondria, but clozapine enhanced the efficacy of oxidative phosphorylation and expression of galactocerebroside. Our findings support the superior impact of clozapine on white matter integrity in schizophrenia as previously observed, suggesting that this drug improves the energy supply and myelin lipid synthesis in oligodendrocytes. Characterizing the underlying signal transduction pathways may pave the way for novel oligodendrocyte-directed schizophrenia therapies.

Harnessing the power of yeast to elucidate the role of sphingolipids in metabolic and signaling processes pertinent to psychiatric disorders

The development of therapies for neuropsychiatric disorders is hampered by the lack of understanding of the mechanisms underlying their pathologies. While aberrant sphingolipid metabolism is associated with psychiatric illness, the role of sphingolipids in these disorders is not understood. The genetically tractable yeast model can be exploited in order to elucidate the cellular consequences of sphingolipid perturbation. Hypotheses generated from studies in yeast and tested in mammalian cells may contribute to our understanding of the role of sphingolipids in psychiatric disorders and to the development of new treatments. Here, we compare sphingolipid metabolism in yeast and mammalian cells, discuss studies implicating sphingolipids in psychiatric disorders and propose approaches that utilize yeast in order to elucidate sphingolipid function and identify drugs that target sphingolipid synthesis.

Lipidomics reveals dysfunctional glycosynapses in schizophrenia and the G72/G30 transgenic mouse

BACKGROUND

Abnormal structural/functional connectivity has been proposed to underlie the pathophysiology of schizophrenia. However, the biochemical basis of abnormal connectivity remains undefined.

METHODS

We undertook a shotgun lipidomic analysis of over 700 lipids across 26 lipid subclasses in the frontal cortex of schizophrenia subjects and hippocampus of G72/G30 transgenic mice.

RESULTS

We demonstrate that glycosphingolipids and choline plasmalogens, structural lipid pools in myelin, are significantly elevated in the frontal cortex obtained from patients suffering from schizophrenia and the hippocampus of G72/G30 transgenic mice.

CONCLUSIONS

Our data suggest that structural lipid alterations in oligodendrocyte glycosynapses are responsible for dysconnectivity in schizophrenia and that increased expression of G72 protein may play a role in the development of abnormal glycosynapses.

Novel implications of Lingo-1 and its signaling partners in schizophrenia

Myelination and neurite outgrowth both occur during brain development, and their disturbance has been previously been implicated in the pathophysiology of schizophrenia. Leucine-rich repeat and immunoglobulin domain-containing protein (Lingo-1) is a potent negative regulator of axonal myelination and neurite extension. As co-factors of Lingo-1 signaling (Nogo receptor (NgR), With No Lysine (K) (WNK1) and Myelin transcription factor 1 (Myt1)) have been implicated in the genetics of schizophrenia, we explored for the first time the role of Lingo-1 signaling pathways in this disorder. Lingo-1 protein, together with its co-receptor and co-factor proteins NgR, tumor necrosis factor (TNF) receptor orphan Y (TROY), p75, WNK1 and Myt1, have never been explored in the pathogenesis of schizophrenia. We examined protein levels of Lingo-1, NgR, TROY, p75, WNK1, Myt1 and myelin basic protein (MBP) (as a marker of myelination) within the post-mortem dorsolateral prefrontal cortex (DLPFC) (37 schizophrenia patients versus 37 matched controls) and hippocampus (Cornu Ammonis, CA1 and CA3) (20 schizophrenia patients versus 20 matched controls from the same cohort). Both of these brain regions are highly disrupted in the schizophrenia pathophysiology. There were significant increases in Lingo-1 (P<0.001) and Myt1 (P=0.023) and a reduction in NgR (P<0.001) in the DLPFC in schizophrenia subjects compared with controls. There were also increases in both TROY (P=0.001) and WNK1 (P=0.011) in the CA1 of schizophrenia subjects and, in contrast to the DLPFC, there was an increase in NgR (P=0.006) in the CA3 of schizophrenia subjects compared with controls. No significant difference was reported for MBP levels (P>0.05) between the schizophrenia and control groups in the three tested regions. This is the first time that a study has shown altered Lingo-1 signaling in the schizophrenia brain. Our novel findings may present a direct application for the use of a Lingo-1 antagonist to complement current and future schizophrenia therapies.

First experimental evidence of dopamine interactions with negatively charged model biomembranes

Dopamine is essential for receptor-related signal transduction in mammalian central and peripheral nervous systems. Weak interactions between the neurotransmitter and neuronal membranes have been suggested to modulate synaptic transmission; however, binding forces between dopamine and neuronal membranes have not yet been quantitatively described. Herein, for the first time, we have explained the nature of dopamine interactions with model lipid membranes assembled from neutral 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), negatively charged 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG), and the mixture of these two lipids using isothermal titration calorimetry and differential scanning calorimetry. Dopamine binding to anionic membranes is a thermodynamically favored process with negative enthalpy and positive entropy, quantitatively described by the mole ratio partition coefficient, K. K increases with membrane charge to reach its maximal value, 705.4 ± 60.4 M(-1), for membrane composed from pure DMPG. The contribution of hydrophobic effects to the binding process is expressed by the intrinsic partition coefficient, K(0). The value of K(0) = 74.7 ± 6.4 M(-1) for dopamine/DMPG interactions clearly indicates that hydrophobic effects are 10 times weaker than electrostatic forces in this system. The presence of dopamine decreases the main transition temperature of DMPG, but no similar effect has been observed for DMPC. Basing on these results, we propose a simple electrostatic model of dopamine interactions with anionic membranes with the hydrophobic contribution expressed by K(0). We suggest that dopamine interacts superficially with phospholipid membranes without penetrating into the bilayer hydrocarbon core. The model is physiologically important, since neuronal membranes contain a large (even 20%) fraction of anionic lipids.

Investigation of endocannabinoid system genes suggests association between peroxisome proliferator activator receptor-α gene (PPARA) and schizophrenia

Schizophrenia (SZ) is a complex psychiatric disorder with a large genetic burden and an estimated hereditability of 80%. A large number of neuroanatomical and psychopharmacological studies suggest a central role of the endocannabinoid (eCB) system in the susceptibility of the disease. To further investigate this hypothesis, we performed an association study with genes codifying for key elements of the eCB system in a sample of 170 schizophrenic patients and 350 healthy controls of Italian ancestry. A total of 57 Tag SNPs (tSNPs) were selected using HapMap CEU population SNP database spanning the following genes: cannabinoid receptor 1 (CNR1), peroxisome proliferator activator receptor-α (PPARA), fatty acid amide hydrolase (FAAH) and N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD). Seven out of the 32 tSNPs within PPARA (rs4253765, rs4263776, rs6007662, rs1800206, rs4253763, rs6008197 and rs4253655) and 3 out of 12 tSNPs within CNR1 (rs1049353, rs7766029 and rs806366) were nominally associated with SZ (uncorrected p<0.05). The same pattern of association was observed in the genotype analysis, with rs4253765 showing the highest level of significance (uncorrected p=2×10(-3)). None of these associations survived after permutation test. Our findings suggest a potential role for PPARA in the susceptibility to SZ, but further studies on larger independent samples are warranted in order to clarify the involvement of this gene in the pathophysiology of SZ.

Altered fatty acid concentrations in prefrontal cortex of schizophrenic patients

BACKGROUND

Disturbances in prefrontal cortex phospholipid and fatty acid composition have been reported in patients with schizophrenia (SCZ), often as an incomplete lipid profile or a percent of total lipid concentration. In this study, we quantified absolute concentrations (nmol/g wet weight) and fractional concentrations (i.e. percent of total fatty acids) of several lipid classes and their constituent fatty acids in postmortem prefrontal cortex of SCZ patients (n = 10) and age-matched controls (n = 10).

METHODS

Lipids were extracted, fractionated with thin layer chromatography and assayed.

RESULTS

Mean total lipid, phospholipid, individual phospholipids, plasmalogen, triglyceride and cholesteryl ester concentrations did not differ significantly between the groups. Compared to controls, SCZ brains showed significant increases in several monounsaturated and polyunsaturated fatty acid absolute concentrations in cholesteryl ester. Significant increases or decreases occurred in palmitoleic, linoleic, γ-linolenic and n-3 docosapentaenoic acid absolute concentrations in total lipids, triglycerides or phospholipids. Changes in fractional concentrations did not consistently reflect absolute concentration changes.

CONCLUSION

These findings suggest disturbed prefrontal cortex fatty acid absolute concentrations, particularly within cholesteryl esters, as a pathological aspect of schizophrenia.

Sphingolipids in psychiatric disorders and pain syndromes

Despite the high prevalence and devastating impact of psychiatric disorders, little is known about their etiopathology. In this review, we provide an overview on the participation of sphingolipids and enzymes responsible for their metabolism in mechanisms underlying psychiatric disorders. We focus on the pathway from sphingomyelin to proapoptotic ceramide and the subsequent metabolism of ceramide to sphingosine, which is in turn phosphorylated to yield anti-apoptotic sphingosine-1-phosphate (S1P).The sphingomyelinase/ceramide system has been linked to effects of reactive oxygen species and proinflammatory cytokines in the central nervous system as well as to synaptic transmission. Compared to ubiquitously expressed acid sphingomyelinase, acid and neutral ceramidase and neutral sphingomyelinase are highly active in brain regions. Depressed patients show elevated plasma ceramide levels and increased activities of acid sphingomyelinase which is functionally inhibited by many anti-depressive drugs. Exposure to alcohol is associated with an activation of acid and neutral sphingomyelinase observed in cell culture, mouse models and in alcohol-dependent patients and with increased concentrations of ceramide in various organs.Levels of sphingomyelin and ceramide are altered in erythrocytes and post-mortem brain tissues of schizophrenic patients in addition to changes in expression patterns for serine palmitoyltransferase and acid ceramidase leading to impaired myelination. After induction of anxiety-like behavior in animal models, higher serum levels of S1P were reported to lead to neurodegeneration. Correspondingly, S1P infusion appeared to increase anxiety-like behavior. Significantly upregulated levels of the endogenous ceramide catabolite N,N-dimethylsphingosine were observed in rat models of allodynia. Conversely, rats injected intrathecally with N,N-dimethylsphingosine developed mechanical allodynia. Moreover, S1P has been implicated in spinal nociceptive processing.The increasing interest in lipidomics and improved analytical methods led to growing insight into the connection between psychiatric and neurological disorders and sphingolipid metabolism and may once provide new targets and strategies for therapeutic intervention.

Proteomics as a tool for understanding schizophrenia

Schizophrenia is likely to be a multifactorial disorder, consequence of alterations in gene and protein expression since the neurodevelopment that together to environmental factors will trigger the establishment of the disease. In the post-genomic era, proteomics has emerged as a promising strategy for revealing disease and treatment biomarkers as well as a tool for the comprehension of the mechanisms of schizophrenia pathobiology. Here, there is a discussion of the potential pathways and structures that are compromised in schizophrenia according to proteomic findings while studying five distinct brain regions of post-mortem tissue from schizophrenia patients and controls. Proteins involved in energy metabolism, calcium homeostasis, myelinization, and cytoskeleton have been recurrently found to be differentially expressed in schizophrenia brains. These findings may encourage new studies on the understanding of schizophrenia biochemical pathways and even new potential drug targets.

Understanding aberrant white matter development in schizophrenia: an avenue for therapy?

Although historically gray matter changes have been the focus of neuropathological and neuroradiological studies in schizophrenia, in recent years an increasing body of research has implicated white matter structures and its constituent components (axons, their myelin sheaths and supporting oligodendrocytes). This article summarizes this body of literature, examining neuropathological, neurogenetic and neuroradiological evidence for white matter pathology in schizophrenia. We then look at the possible role that antipsychotic medication may play in these studies, examining both its role as a potential confounder in studies examining neuronal density and brain volume, but also the possible role that these medications may play in promoting myelination through their effects on oligodendrocytes. Finally, the role of potential novel therapies is discussed.

The role of energy metabolism dysfunction and oxidative stress in schizophrenia revealed by proteomics

Schizophrenia is a psychiatric illness that affects approximately 30 million people worldwide. Converging lines of evidence suggest that mitochondrial function may be compromised in this disorder, and this can lead to perturbations in calcium buffering, oxidative phosphorylation, increased production of reactive oxygen species, and apoptotic factors, which can, in turn, affect neuronal processes such as neurotransmitter synthesis and synaptic plasticity. Proteomics studies in brain and peripheral tissues of schizophrenia patients have provided considerable evidence and identified biomarker fingerprints corresponding to such pathways. Here we review the results of these studies with a focus on the biomarker pattern depicting alterations in energy metabolism and oxidative stress in this debilitating illness.

Antioxidants, redox signaling, and pathophysiology in schizophrenia: an integrative view

Schizophrenia (SZ) is a brain disorder that has been intensively studied for over a century; yet, its etiology and multifactorial pathophysiology remain a puzzle. However, significant advances have been made in identifying numerous abnormalities in key biochemical systems. One among these is the antioxidant defense system (AODS) and redox signaling. This review summarizes the findings to date in human studies. The evidence can be broadly clustered into three major themes: perturbations in AODS, relationships between AODS alterations and other systems (i.e., membrane structure, immune function, and neurotransmission), and clinical implications. These domains of AODS have been examined in samples from both the central nervous system and peripheral tissues. Findings in patients with SZ include decreased nonenzymatic antioxidants, increased lipid peroxides and nitric oxides, and homeostatic imbalance of purine catabolism. Reductions of plasma antioxidant capacity are seen in patients with chronic illness as well as early in the course of SZ. Notably, these data indicate that many AODS alterations are independent of treatment effects. Moreover, there is burgeoning evidence indicating a link among oxidative stress, membrane defects, immune dysfunction, and multineurotransmitter pathologies in SZ. Finally, the body of evidence reviewed herein provides a theoretical rationale for the development of novel treatment approaches.

Extracellular matrix abnormalities in schizophrenia

Emerging evidence points to the involvement of the brain extracellular matrix (ECM) in the pathophysiology of schizophrenia (SZ). Abnormalities affecting several ECM components, including Reelin and chondroitin sulfate proteoglycans (CSPGs), have been described in subjects with this disease. Solid evidence supports the involvement of Reelin, an ECM glycoprotein involved in corticogenesis, synaptic functions and glutamate NMDA receptor regulation, expressed prevalently in distinct populations of GABAergic neurons, which secrete it into the ECM. Marked changes of Reelin expression in SZ have typically been reported in association with GABA-related abnormalities in subjects with SZ and bipolar disorder. Recent findings from our group point to substantial abnormalities affecting CSPGs, a main ECM component, in the amygdala and entorhinal cortex of subjects with schizophrenia, but not bipolar disorder. Striking increases of glial cells expressing CSPGs were accompanied by reductions of perineuronal nets, CSPG- and Reelin-enriched ECM aggregates enveloping distinct neuronal populations. CSPGs developmental and adult functions, including neuronal migration, axon guidance, synaptic and neurotransmission regulation are highly relevant to the pathophysiology of SZ. Together with reports of anomalies affecting several other ECM components, these findings point to the ECM as a key component of the pathology of SZ. We propose that ECM abnormalities may contribute to several aspects of the pathophysiology of this disease, including disrupted connectivity and neuronal migration, synaptic anomalies and altered GABAergic, glutamatergic and dopaminergic neurotransmission.

Association study of Nogo-related genes with schizophrenia in a Japanese case-control sample

Many studies have suggested that myelin dysfunction may be causally involved in the pathogenesis of schizophrenia. Nogo (RTN4), myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMG) all bind to the common receptor, Nogo-66 receptor 1 (RTN4R). We examined 68 single nucleotide polymorphisms (SNPs) (51 with genotyping and 17 with imputation analysis) from these four genes for genetic association with schizophrenia, using a 2,120 case-control sample from the Japanese population. Allelic tests showed nominally significant association of two RTN4 SNPs (P = 0.047 and 0.037 for rs11894868 and rs2968804, respectively) and two MAG SNPs (P = 0.034 and 0.029 for rs7249617 and rs16970218, respectively) with schizophrenia. The MAG SNP rs7249617 also showed nominal significance in a genotypic test (P = 0.017). In haplotype analysis, the MAG haplotype block including rs7249617 and rs16970218 showed nominal significance (P = 0.008). These associations did not remain significant after correction for multiple testing, possibly due to their small genetic effect. In the imputation analysis of RTN4, the untyped SNP rs2972090 showed nominally significant association (P = 0.032) and several imputed SNPs showed marginal associations. Moreover, in silico analysis (PolyPhen) of a missense variant (rs11677099: Asp357Val), which is in strong linkage disequilibrium with rs11894868, predicted a deleterious effect on Nogo protein function. Despite a failure to detect robust associations in this Japanese cohort, our nominally positive signals, taken together with previously reported biological and genetic findings, add further support to the "disturbed myelin system theory of schizophrenia" across different populations.

Abnormal phospholipids distribution in the prefrontal cortex from a patient with schizophrenia revealed by matrix-assisted laser desorption/ionization imaging mass spectrometry

Schizophrenia is one of the major psychiatric disorders, and lipids have focused on the important roles in this disorder. In fact, lipids related to various functions in the brain. Previous studies have indicated that phospholipids, particularly ones containing polyunsaturated fatty acyl residues, are deficient in postmortem brains from patients with schizophrenia. However, due to the difficulties in handling human postmortem brains, particularly the large size and complex structures of the human brain, there is little agreement regarding the qualitative and quantitative abnormalities of phospholipids in brains from patients with schizophrenia, particularly if corresponding brain regions are not used. In this study, to overcome these problems, we employed matrix-assisted laser desorption/ionization imaging mass spectrometry (IMS), enabling direct microregion analysis of phospholipids in the postmortem brain of a patient with schizophrenia via brain sections prepared on glass slides. With integration of traditional histochemical examination, we could analyze regions of interest in the brain at the micrometric level. We found abnormal phospholipid distributions within internal brain structures, namely, the frontal cortex and occipital cortex. IMS revealed abnormal distributions of phosphatidylcholine molecular species particularly in the cortical layer of frontal cortex region. In addition, the combined use of liquid chromatography/electrospray ionization tandem mass spectrometry strengthened the capability for identification of numerous lipid molecular species. Our results are expected to further elucidate various metabolic processes in the neural system.

Altered 13C glucose metabolism in the cortico-striato-thalamo-cortical loop in the MK-801 rat model of schizophrenia

Using a modified MK-801 (dizocilpine) N-methyl-D-aspartic acid (NMDA) receptor hypofunction model for schizophrenia, we analyzed glycolysis, as well as glutamatergic, GABAergic, and monoaminergic neurotransmitter synthesis and degradation. Rats received an injection of MK-801 daily for 6 days and on day 6, they also received an injection of [1-(13)C]glucose. Extracts of frontal cortex (FCX), parietal and temporal cortex (PTCX), thalamus, striatum, nucleus accumbens (NAc), and hippocampus were analyzed using (13)C nuclear magnetic resonance spectroscopy, high-performance liquid chromatography, and gas chromatography-mass spectrometry. A pronounced reduction in glycolysis was found only in PTCX, in which (13)C labeling of glucose, lactate, and alanine was decreased. (13)C enrichment in lactate, however, was reduced in all areas investigated. The largest reductions in glutamate labeling were detected in FCX and PTCX, whereas in hippocampus, striatum, and Nac, (13)C labeling of glutamate was only slightly but significantly reduced. The thalamus was the only region with unaffected glutamate labeling. γ-Aminobutyric acid (GABA) labeling was reduced in all areas, but most significantly in FCX. Glutamine and aspartate labeling was unchanged. Mitochondrial metabolites were also affected. Fumarate labeling was reduced in FCX and thalamus, whereas malate labeling was reduced in FCX, PTCX, striatum, and NAc. Dopamine turnover was decreased in FCX and thalamus, whereas that of serotonin was unchanged in all regions. In conclusion, neurotransmitter metabolism in the cortico-striato-thalamo-cortical loop is severely impaired in the MK-801 (dizocilpine) NMDA receptor hypofunction animal model for schizophrenia.

Proteome analysis of the thalamus and cerebrospinal fluid reveals glycolysis dysfunction and potential biomarkers candidates for schizophrenia

Schizophrenia (SCZ) is the result of DNA alterations and environmental factors, which together lead to differential protein expression and ultimately to the development of the illness. The diagnosis is based on clinical symptoms, and the molecular background of SCZ is not completely understood. The thalamus, whose dysfunction has been associated with SCZ based in diverse lines of evidences, plays for instance a pivotal role in the central nervous system as a relay center by re-distributing auditory and visual stimuli from diverse brain regions to the cerebral cortex. We analyzed the proteome of postmortem mediodorsal thalamus (MDT) samples from 11 SCZ patients and 8 non-SCZ individuals by using quantitative shotgun-mass spectrometry and two-dimensional gel electrophoresis. Our analyses identified 551 proteins, 50 of which showed significant differential expression. The main pathways affected by the differentially expressed proteins include energy metabolism, oligodendrocyte metabolism, and cytoskeleton assembly. The potential protein biomarkers candidates myelin basic protein and myelin oligodendrocyte protein were validated by Western blot in the MDT samples and also in cerebrospinal fluid from a separate set of samples of 17 first-episode SCZ patients and 10 healthy controls. The differential expression of μ-crystallin, protein kinase C-gamma, and glial fibrillary acidic protein were confirmed in MDT. Because we found several glycolysis enzymes to be differentially expressed, we measured the levels of pyruvate and NADPH and found them to be altered in MDT. The protein changes described here corroborate the importance of myelin/oligodendrocyte and energy metabolism in SCZ and highlight new potential biomarkers candidates that may contribute to the understanding of the pathogenesis of this complex disease.

Different apolipoprotein E, apolipoprotein A1 and prostaglandin-H2 D-isomerase levels in cerebrospinal fluid of schizophrenia patients and healthy controls

OBJECTIVES

To identify proteins differentially expressed in schizophrenia patients, we collected 50 microl cerebrospinal fluid from 17 first-episode schizophrenia patients and 10 healthy controls.

METHODS

Their proteins were separated by two-dimensional gel electrophoresis without using any depletion method and identified by mass spectrometry.

RESULTS

Approximately 550 spots were detected, six of which had significantly different intensities in schizophrenia compared to control specimens. We were able to validate in individual samples the upregulation of apolipoprotein E, apolipoprotein A1 and prostaglandin-H2 D-isomerase by Western blot analyses and detect the downregulation of transthyretin, TGF-beta receptor type-1 and coiled-coil domain-containing protein 3 precursor.

CONCLUSIONS

These findings may help to elucidate the disease mechanisms and confirm the hypothesis of disturbed cholesterol and phospholipid metabolism in schizophrenia, and thus reveal the final role players. Moreover, a grouped protein expression analysis of apolipoprotein E, apolipoprotein A-I, and prostaglandin-H2 D-isomerase in cerebrospinal fluid from patients might be a potential diagnostic tool for schizophrenia.

White matter abnormalities in first-episode schizophrenia: a combined structural MRI and DTI study

This study examined white matter volume change and integrity jointly in patients with first-episode schizophrenia using an empirically derived region of interest approach and novel Diffusion Tensor Imaging (DTI) geometric indices. Structural images from 103 individuals comprising of 39 patients with first-episode schizophrenia and 64 healthy controls were examined for regions of white matter volume change using voxel-based morphometry (VBM). These regions were then further interrogated for group differences employing geometric indices in addition to fractional anisotropy (FA).VBM analyses revealed that patients with first-episode schizophrenia had lower white matter volume in the right temporal-occipital region (p<0.005) corresponding to the inferior longitudinal fasciculus. Further analyses of diffusion anisotropy in the right temporal-occipital region revealed lower planar anisotropy, and higher linear anisotropy (p=0.012) in patients. FA in the implicated region was also found to be correlated with severity of delusions (r=0.47, p=0.004).We confirmed previous findings of lower white matter volume in the region of inferior longitudinal fasciculus. The presence of changes in geometric diffusion indices in the implicated white matter region suggested that pathophysiological processes which underlie cerebral white matter volume reduction may not be reflected by changes in FA. Further research is needed to better understand the nature of these white matter changes and its progression in schizophrenia over time.

Effects of sub-chronic clozapine and haloperidol administration on brain lipid levels

Abnormal lipid profiles have been reported in the central nervous system (CNS) in individuals with schizophrenia, although the etiology of these changes remains to be elucidated. While treatment with second-generation antipsychotics has been associated with alterations in peripheral lipid levels and changes in erythrocyte membrane composition, the relationship between peripheral and CNS lipid levels is complex and the effect of antipsychotics on CNS lipid regulation is not yet understood. In this study we investigated whether sub-chronic administration of the second-generation antipsychotic clozapine and the first-generation antipsychotic haloperidol alters brain membrane lipid composition in male Sprague-Dawley rats. The relationship between brain membrane lipid composition and plasma cholesterol concentrations was also assessed. Our results indicate that brain lipid composition and plasma cholesterol concentrations are not altered following administration of antipsychotics. No correlation was observed between plasma and brain membrane cholesterol levels. Our findings suggest that observed alterations in brain lipid profiles in individuals with schizophrenia are not a consequence of treatment with antipsychotic medications.

The efficacy of a voxel-based morphometry on the analysis of imaging in schizophrenia, temporal lobe epilepsy, and Alzheimer's disease/mild cognitive impairment: a review

Voxel-based morphometry (VBM) done by means of MRI have provided new insights into the neuroanatomical basis for subjects with several conditions. Recently, VBM has been applied to investigate not only regional volumetric changes but also voxel-wise maps of fractional anisotropy (FA) computed from diffusion tensor imaging (DTI). The aim of this article is to review the recent work using VBM technique in particular focusing on schizophrenia, temporal lobe epilepsy (TLE), and Alzheimer's disease (AD)/mild cognitive impairment (MCI). In patients with schizophrenia, VBM approach detects the structural brain abnormalities that appear normal on conventional MRI. Moreover, this technique also has the potential to emerge as a useful clinical tool for early detection and monitoring of disease progression and treatment response in patients with schizophrenia or AD/MCI. In TLE, VBM approach may help elucidate some unresolved important research questions such as how recurrent temporal lobe seizures affect hippocampal and extrahippocampal morphology. Thus, in the future, large cohort studies to monitor whole brain changes on a VBM basis will lead to a further understanding of the neuropathology of several conditions.

Thalamic nuclear abnormalities as a contributory factor in sudden cardiac deaths among patients with schizophrenia

Patients with schizophrenia have a two- to three-fold increased risk of premature death as compared to patients without this disease. It has been established that patients with schizophrenia are at a high risk of developing cardiovascular disease. Moreover, an important issue that has not yet been explored is a possible existence of a "cerebral" focus that could trigger sudden cardiac death in patients with schizophrenia. Along these lines, several structural and functional alterations in the thalamic complex are evident in patients with schizophrenia and have been correlated with the symptoms manifested by these patients. With regard to abnormalities on the cellular and molecular level, previous studies have shown that schizophrenic patients have fewer neuronal projections from the thalamus to the prefrontal cortex as well as a reduced number of neurons, a reduced volume of either the entire thalamus or its subnuclei, and abnormal glutamate signaling. According to the glutamate hypothesis of schizophrenia, hypofunctional corticostriatal and striatothalamic projections are directly involved in the pathophysiology of the disease. Animal and post-mortem studies have provided a large amount of evidence that links the sudden unexpected death in epilepsy (SUDEP) that occurs in patients with schizophrenia and epilepsy to thalamic changes. Based on the results of these prior studies, it is clear that further research regarding the relationship between the thalamus and sudden cardiac death is of vital importance.

Proteome and transcriptome analysis suggests oligodendrocyte dysfunction in schizophrenia

Despite all the efforts regarding the treatment of schizophrenia patients and the growing advances in molecular diagnosis studies, the biochemical basis of this debilitating psychotic mental disorder that affects approximately 1% of the world's population is still not completely comprehended. Several recent clinical and molecular studies, using transcriptome and proteome analyses (TPA), for example, have described the oligodendrocyte dysfunction as a significant feature of the disease. TPA has been extensively used as a biomarker discovery tool, but a detailed and careful interpretation of the generated data can also provide a picture of the integrated biochemical systems that lead to the disease. This review presents the oligodendrocyte role players in schizophrenia pathogenesis as revealed by transcriptome and proteome studies. The presented data contribute to the composition of a scenario that may lead to a better understanding of schizophrenia pathogenesis.

A cytogenetic abnormality and rare coding variants identify ABCA13 as a candidate gene in schizophrenia, bipolar disorder, and depression

Schizophrenia and bipolar disorder are leading causes of morbidity across all populations, with heritability estimates of approximately 80% indicating a substantial genetic component. Population genetics and genome-wide association studies suggest an overlap of genetic risk factors between these illnesses but it is unclear how this genetic component is divided between common gene polymorphisms, rare genomic copy number variants, and rare gene sequence mutations. We report evidence that the lipid transporter gene ABCA13 is a susceptibility factor for both schizophrenia and bipolar disorder. After the initial discovery of its disruption by a chromosome abnormality in a person with schizophrenia, we resequenced ABCA13 exons in 100 cases with schizophrenia and 100 controls. Multiple rare coding variants were identified including one nonsense and nine missense mutations and compound heterozygosity/homozygosity in six cases. Variants were genotyped in additional schizophrenia, bipolar, depression (n > 1600), and control (n > 950) cohorts and the frequency of all rare variants combined was greater than controls in schizophrenia (OR = 1.93, p = 0.0057) and bipolar disorder (OR = 2.71, p = 0.00007). The population attributable risk of these mutations was 2.2% for schizophrenia and 4.0% for bipolar disorder. In a study of 21 families of mutation carriers, we genotyped affected and unaffected relatives and found significant linkage (LOD = 4.3) of rare variants with a phenotype including schizophrenia, bipolar disorder, and major depression. These data identify a candidate gene, highlight the genetic overlap between schizophrenia, bipolar disorder, and depression, and suggest that rare coding variants may contribute significantly to risk of these disorders.

Demyelination in the juvenile period, but not in adulthood, leads to long-lasting cognitive impairment and deficient social interaction in mice

BACKGROUND

Dysmyelination is hypothesized to be one of the causes of schizophrenic symptoms. Supporting this hypothesis, demyelination induced by cuprizone was recently shown to cause schizophrenia-like symptoms in adult rodents [Xiao L, Xu H, Zhang Y, Wei Z, He J, Jiang W, et al. Quetiapine facilitates oligodendrocyte development and prevents mice from myelin breakdown and behavioral changes. Mol Psychiatry 2008;13:697-708]. The present study asked if the timing of demyelination (i.e., juvenile period or adulthood) influenced abnormal behavior.

METHODS

B57BL/6 mice were fed with 0.2% cuprizone either from postnatal day 29 (P29) to P56 (early demyelination group) or from P57 to P84 (late demyelination group), and then returned to normal mouse chow until P126, when the behavioral analysis was initiated.

RESULTS

In both groups, the intake of cuprizone for 28 days produced massive demyelination in the corpus callosum by the end of the treatment period, and subsequent normal feeding restored myelination by P126. In a Y-maze test, the spatial working memory was impaired in both groups right after the cuprizone feeding ceased, consistent with previous studies, whereas only the early demyelination group exhibited impaired working memory after remyelination took place. In an open field test, social interactions were decreased in the early demyelination group, but not in the late group. Novel cognition and anxiety-related behaviors were comparable between the two groups.

CONCLUSIONS

Our findings suggest that the timing of demyelination has substantial impacts on behaviors of adult mice.

Evidence for disruption of sphingolipid metabolism in schizophrenia

As the field of glycobiology grows, important roles for glycolipids and glycoproteins in neurological disorders are being increasingly appreciated. However, few studies have explored the involvement of these molecules in the pathology of psychiatric illnesses. We investigated molecular differences related to glycobiology in subjects with schizophrenia by analyzing gene expression profiles using a focused glycogene chip, a custom-designed oligonucleotide array containing genes encoding proteins related to glycobiology, including glycosyltransferases, carbohydrate-binding proteins, proteoglycans, and adhesion molecules. We measured expression profiles in prefrontal cortical (BA46) samples from schizophrenic subjects and matched controls. We find differential expression of genes particularly related to glycosphingolipid/sphingolipid metabolism and N- and O-linked glycan biosynthesis in subjects with schizophrenia. Expression decreases of seven genes associated with these pathways, UGT8, SGPP1, GALC, B4GALT6, SPTLC2, ASAH1, and GAL3ST1, were validated by quantitative PCR in schizophrenic subjects with short-term illness. Only one of these genes, SPTLC2, showed differential expression in chronic schizophrenic subjects, although an increase in expression was observed. Covariate analysis showed that the expression of five of these genes was significantly positively correlated with age in schizophrenic, but not control, subjects. These changing patterns of expression could represent an adaptive response to pathology with disease progression or a compensatory effect of antipsychotic medication, although no significant correlations between gene expression levels and drug doses were observed. Disruption of sphingolipid metabolism early in illness could result in widespread downstream effects encompassing diverse pathological deficits already described in schizophrenia, especially those involving myelination and oligodendrocyte function; hence, this system may represent an important link in schizophrenia pathology.

Spatial distribution and density of oligodendrocytes in the cingulum bundle are unaltered in schizophrenia

It has been proposed that schizophrenia results partly from altered brain connectivity. Gene microarray analyses performed in gray matter have indicated that several myelin-related genes normally expressed in oligodendrocytes have decreased expression levels in schizophrenia. These data suggest that oligodendrocytes may be involved in the deficits of schizophrenia and may be decreased in number in the case of disease. The anterior cingulate cortex in particular has been demonstrated to be affected in schizophrenia, with studies reporting altered neuronal arrangement, decreased anisotropy in diffusion tensor images, and hypometabolism. We used a stereologic nearest-neighbor estimator of spatial distribution to investigate oligodendrocytes in the anterior cingulum bundle using postmortem tissue from 13 chronic schizophrenics and 13 age-matched controls. Using a spatial point pattern analysis, we measured the degree of oligodendrocyte clustering by comparing the probability of finding a nearest-neighbor at a given distance in schizophrenics and controls. At the same time, we also estimated the number and density of oligodendrocytes in the region of interest. In the present study, we found no significant differences in the oligodendrocyte distribution or density in the cingulum bundle between the two groups, in contrast to earlier data from the prefrontal subcortical white matter. These results suggest that a subtler oligodendrocyte or myelin anomaly may underlie the structural deficits observed by brain imaging in the cingulum bundle in schizophrenia.

Common effect of antipsychotics on the biosynthesis and regulation of fatty acids and cholesterol supports a key role of lipid homeostasis in schizophrenia

For decades, the dopamine hypothesis has gained the most attention in an attempt to explain the origin and the symptoms of schizophrenia. While this hypothesis offers an explanation for the relationship between psychotic symptoms and dopamine kinetics, it does not provide a direct explanation of the etiology of schizophrenia which remains poorly understood. Consequently, current antipsychotics that target neurotransmitter receptors, have limited and inconsistent efficacy. To gain insights into the mechanism of action of these drugs, we studied the expression profile of 12,490 human genes in a cell line treated with 18 antipsychotics, and compared it to that of a library of 448 other compounds used in a variety of disorders. Analysis reveals a common effect of antipsychotics on the biosynthesis and regulation of fatty acids and cholesterol, which is discussed in the context of a lipid hypothesis where alterations in lipid homeostasis might underlie the pathogenesis of schizophrenia. This finding may help research aimed at the development of novel treatments for this devastating disease.

Phospholipid composition of postmortem schizophrenic brain by 31P NMR spectroscopy

Cell membrane abnormalities due to changes in phospholipid (PL) composition and metabolism have been implicated in schizophrenia pathogenesis. That work has generally assessed membrane phospholipids from nonneural tissues such as erythrocytes and platelets. High-resolution (31)P NMR spectroscopy was used to characterize PLs of gray matter in postmortem brain for 20 schizophrenics, 20 controls, and 7 patients with other mental illnesses (psychiatric controls). Tissues from frontal, temporal, and occipital cortices were extracted with hexane-isopropanol, and (31)P NMR spectra were obtained in an organic-solvent system to resolve the major PL classes (based on headgroups) and subclasses (based on linkage at the sn - 1 position). Surprisingly, repeated-measures multivariate analysis of variance revealed no overall differences among the groups. There were no significant differences (P < .05) among the three groups for any individual PL subclass, including lysophospholipids. The sum of all phosphatidylethanolamine headgroups was significantly lower for schizophrenics than for controls or psychiatric controls in the frontal cortex. The present results are minimally correlated with previous results for aqueous PL metabolites on these same samples. The metabolite changes measured by in vivo (31)P MRS in schizophrenia do not appear to reflect PL concentration changes. The present results offer very little support for the phospholipid hypothesis of schizophrenia.

An association screen of myelin-related genes implicates the chromosome 22q11 PIK4CA gene in schizophrenia

Several lines of evidence, including expression analyses, brain imaging and genetic studies suggest that the integrity of myelin is disturbed in schizophrenia patients. In this study, we first reconstructed a pathway of 138 myelin-related genes, all involved in myelin structure, composition, development or maintenance. Then we performed a two-stage association analysis on these 138 genes using 771 single nucleotide polymorphisms (SNPs). Analysis of our data from 310 cases vs 880 controls demonstrated association of 10 SNPs from six genes. Specifically, we observed highly significant P-values for association in PIK4CA (observed P=6.1 x 10(-6)). These findings remained significant after Bonferroni correction for 771 tests. The PIK4CA gene is located in the chromosome 22q11 deletion syndrome region, which is of particular interest because it has been implicated in schizophrenia. We also report weak association of SNPs in PIK3C2G, FGF1, FGFR1, ARHGEF10 and PSAP (observed P<or=0.01). Our approach--of screening genes involved in a particular pathway for association--resulted in identification of several, mostly novel, genes associated with the risk of developing schizophrenia in the Dutch population.

High throughput lipidomic profiling of schizophrenia and bipolar disorder brain tissue reveals alterations of free fatty acids, phosphatidylcholines, and ceramides

A mass spectrometry based high throughput approach was employed to profile white and gray matter lipid levels in the prefrontal cortex (Brodmann area 9) of 45 subjects including 15 schizophrenia and 15 bipolar disorder patients as well as 15 controls samples. We found statistically significant alterations in levels of free fatty acids and phosphatidylcholine in gray and white matter of both schizophrenia and bipolar disorder samples compared to controls. Also, ceramides were identified to be significantly increased in white matter of both neuropsychiatric disorders as compared to control levels. The patient cohort investigated in this study includes a number of drug naive as well as untreated patients, allowing the assessment of drug effects on lipid levels. Our findings indicate that while gray matter phosphatidylcholine levels were influenced by antipsychotic medication, this was not the case for phosphatidylcholine levels in white matter. Changes in free fatty acids or ceramides in either white or gray matter also did not appear to be influenced by antipsychotic treatment. To assess lipid profiles in the living patient, we also profiled lipids of 40 red blood cell samples, including 7 samples from drug naive first onset patients. We found significant alterations in the concentrations of free fatty acids as well as ceramide. Overall, our findings suggest that lipid abnormalities may be a disease intrinsic feature of both schizophrenia and bipolar disorder reflected by significant changes in the central nervous system as well as peripheral tissues.

Disturbed structural connectivity in schizophrenia primary factor in pathology or epiphenomenon?

Indirect evidence for disturbed structural connectivity of subcortical fiber tracts in schizophrenia has been obtained from functional neuroimaging and electrophysiologic studies. During the past few years, new structural imaging methods have become available. Diffusion tensor imaging and magnetization transfer imaging (MTI) have been used to investigate directly whether fiber tract abnormalities are indeed present in schizophrenia. To date, findings are inconsistent that may express problems related to methodological issues and sample size. Also, pathological processes detectable with these new techniques are not yet well understood. Nevertheless, with growing evidence of disturbed structural connectivity, myelination has been in the focus of postmortem investigations. Several studies have shown a significant reduction of oligodendroglial cells and ultrastructural alterations of myelin sheats in schizophrenia. There is also growing evidence for abnormal expression of myelin-related genes in schizophrenia: Neuregulin (NRG1) is important for oligodendrocyte development and function, and altered expression of erbB3, one of the NRG1 receptors, has been shown in schizophrenia patients. This is consistent with recent genetic studies suggesting that NRG1 may contribute to the genetic risk for schizophrenia. In conclusion, there is increasing evidence from multiple sides that structural connectivity might be pathologically changed in schizophrenia illness. Up to the present, however, it has not been possible to decide whether alterations of structural connectivity are intrinsically linked to the primary risk factors for schizophrenia or to secondary downstream effects (ie, degeneration of fibers secondarily caused by cortical neuronal dysfunction)-an issue that needs to be clarified by future research.

Differential effects of typical and atypical antipsychotics on brain myelination in schizophrenia

CONTEXT

Imaging and post-mortem studies provide converging evidence that patients with schizophrenia have a dysregulated developmental trajectory of frontal lobe myelination even in adulthood. Atypical antipsychotics have been shown to have a wide spectrum of efficacy across multiple psychiatric diseases and to be particularly efficacious in treatment resistant cases of disorders such as schizophrenia.

OBJECTIVE

To test the a priori hypothesis that antipsychotic medications may differentially impact frontal lobe myelination in patients with schizophrenia.

DESIGN, SETTING, AND PARTICIPANTS

Participants ranged in age from 18-35 years, were all male, and were recruited by a single group of investigators using the same criteria. Two cohorts of subjects with schizophrenia early in their disease who were treated either with oral risperidone (Ris) or fluphenazine decanoate (Fd) were imaged in conjunction with cohorts of healthy controls. Each cohort was imaged using a different MRI instrument using identical imaging sequences.

MAIN OUTCOME MEASURE

MRI measures of frontal lobe white matter volume.

RESULTS

We estimated differences due to differences in the MRI instruments used in the two studies in the two healthy control groups matched to the patient samples, adjusting for age and other covariates. We then statistically removed those differences (which we assumed were due to instrument effects) from the data in the schizophrenia samples by subtraction. Relative to the differences seen in controls, the two groups of schizophrenic patients differed in their pattern of frontal lobe structure with the Ris-treated group having significantly larger white matter volume than the Fd group.

CONCLUSIONS

The results suggest that the choice of antipsychotic treatment may differentially impact brain myelination in adults with schizophrenia. Prospective studies are needed to confirm this finding. MRI can be used to dissect subtle differences in brain tissue characteristics and thus could help clarify the effect of pharmacologic treatments on neurodevelopmental and pathologic processes in vivo.

Extended neocortical maturation time encompasses speciation, fatty acid and lateralization theories of the evolution of schizophrenia and creativity

I suggest that the extended maturation time of some regions of the human neocortex is the uniquely human factor which allows the development of language, creativity and madness. The genetic event or events which contribute to the long delay to final maturation occurred at or after the speciation of Homo sapiens sapiens. Neocortical growth may follow the previously detailed "balloon model", which suggests that intra- and subcortical myelin production during development physically stretches each local area of the cortex tangentially to the pial surface, thereby causing neuronal columns to become more disjoint and more functionally independent, thereby increasing the functional capacity of the area [Seldon HL. Does brain white matter growth expand the cortex like a balloon? Hypothesis and consequences. Laterality 2005;10(1):81-95]. This occurs in addition to Hebbian synaptic modeling. Therefore, the size and functional capacity of each cytoarchitectonic area of each individual adult neocortex are the outcomes of partly deterministic (e.g., genetic) and partly statistical growth processes with numerous factors including environmental stimuli and fatty acid content in diets. The possible functional capacity and variation among growth outcomes increase with the length of time allowed to "finalize" synaptic weights, myelination and other plastic processes. For example, acquisition of quite differing linguistic skills becomes possible only in Homo sapiens because of the extended, decades-long plasticity of temporal lobe areas; in contrast, tactile skills vary little among human races and cultures, or even among higher primates, because of the faster maturation of the somatomotor areas. Some of the statistically extreme variations of the neocortical growth processes lead to abnormal cognition and behavior called "madness" or "genius". This maturation hypothesis overcomes some problems with those based purely on fatty acid metabolism or on functional asymmetry (non-human species show functional asymmetry, but no language. Neanderthals had brains comparable in size and shape to ours, but failed to develop language or creativity). This hypothesis implies that the search for genetic factors should include those which influence the temporal regulation of neuronal and myelin growth, but it also allows the development of unusual creativity or madness as a statistical extreme in the absence of any deterministic factors. It has implications about our attitudes toward mental "disorders" and about potential approaches to treating some of them - for example, attempting communication and conditioning via those senses and cortical areas which show less variation and are less affected.

How a neuropsychiatric brain bank should be run: a consensus paper of Brainnet Europe II

The development of new molecular and neurobiological methods, computer-assisted quantification techniques and neurobiological investigation methods which can be applied to the human brain, all have evoked an increased demand for post-mortem tissue in research. Psychiatric disorders are considered to be of neurobiological origin. Thus far, however, the etiology and pathophysiology of schizophrenia, depression and dementias are not well understood at the cellular and molecular level. The following will outline the consensus of the working group for neuropsychiatric brain banking organized in the Brainnet Europe II, on ethical guidelines for brain banking, clinical diagnostic criteria, the minimal clinical data set of retrospectively analyzed cases as well as neuropathological standard investigations to perform stageing for neurodegenerative disorders in brain tissue. We will list regions of interest for assessments in psychiatric disorder, propose a dissection scheme and describe preservation and storage conditions of tissue. These guidelines may be of value for future implementations of additional neuropsychiatric brain banks world-wide.

Antipsychotic drugs activate SREBP-regulated expression of lipid biosynthetic genes in cultured human glioma cells: a novel mechanism of action?

Several studies have reported on structural abnormalities, decreased myelination and oligodendrocyte dysfunction in post-mortem brains from schizophrenic patients. Glia-derived cholesterol is essential for both myelination and synaptogenesis in the CNS. Lipogenesis and myelin synthesis are thus interesting etiological candidate targets in schizophrenia. Using a microarray approach, we here demonstrate that the antipsychotic drugs clozapine and haloperidol upregulate several genes involved in cholesterol and fatty acid biosynthesis in cultured human glioma cells, including HMGCR (3-hydroxy-3-methylglutaryl-coenzyme A reductase), HMGCS1 (3-hydroxy-3-methylglutaryl-coenzyme A synthase-1), FASN (fatty acid synthase) and SCD (stearoyl-CoA desaturase). The changes in gene expression were followed by enhanced HMGCR-enzyme activity and elevated cellular levels of cholesterol and triglycerides. The upregulated genes are all known to be controlled by the sterol regulatory element-binding protein (SREBP) transcription factors. We show that clozapine and haloperidol both activate the SREBP system. The antipsychotic-induced SREBP-mediated increase in glial cell lipogenesis could represent a novel mechanism of action, and may also be relevant for the metabolic side effects of antipsychotics.

Brain lipid composition in postnatal iron-induced motor behavior alterations following chronic neuroleptic administration in mice

Several studies have shown that deficient uptake or excessive break down of membrane phospholipids may be associated with neurodegenerative and psychiatric disorders. The purpose of the present study was to examine the effects of postnatal iron administration in lipid composition and behavior and whether or not the established effects may be altered by subchronic administration of the neuroleptic compounds, clozapine and haloperidol. In addition to motor activities such as locomotion, rearing and activity, a targeted lipidomics approach has been used to investigated the brains of eight groups of mice (four vehicle groups and four iron groups) containing six individuals in each group treated with vehicle, low dose clozapine, high dose clozapine and haloperidol. Lipids were extracted by the Folch method and analyzed using reversed-phase capillary liquid chromatography coupled on-line to electrospray ionization mass spectrometry (LC/ESI/MS). Identification of phosphatidylcholine (PC) and sphingomyelin (SM) molecular species was based on their retention time, m/z ratio, head group specific up-front fragmentation and analysis of the product ions produced upon fragmentation. A comparison between the Ve-groups and Fe-groups showed that levels of PC and SM molecular species and motor activities were significantly lower in Fe-Ve compared to Ve-Ve. The effects of neuroleptic treatment with and without iron supplementation were studied. In conclusion our results support the hypothesis that an association between psychiatric disorders and lipid and behavior abnormalities in the brain exists.