Mitochondrial pathology in human schizophrenic striatum: a postmortem ultrastructural study

Microglia-neuron interactions in prefrontal gray matter in schizophrenia: a postmortem ultrastructural morphometric study

This study addressed the question of whether the interaction between neurons and satellite microglia (SatMg) is abnormal in schizophrenia. SatMg-neuron communication at direct contacts between neuronal soma is essential for neuroplasticity as SatMg can regulate neuronal activity. A postmortem ultrastructural morphometric study was performed to investigate SatMg and adjacent neurons in layer 5 of the prefrontal cortex in 21 cases of schizophrenia and 20 healthy controls. Density of SatMg was significantly higher in the young schizophrenia group and in the group with illness duration ≤ 26 years as compared to controls. We found lower volume fraction (Vv) and the number (N) of mitochondria and higher Vv and N of lipofuscin granules and vacuoles in endoplasmic reticulum in SatMg in the schizophrenia compared to the control brain. These changes progressed with age and illness duration. A significantly higher soma area and Vv of vacuoles of endoplasmic reticulum were revealed in neurons in schizophrenia as compared to controls. Negative significant correlations between N of vacuoles in neurons and N of mitochondria in SatMg were found in the control group but not in the schizophrenia group. Area of vacuole in neurons was significantly positively correlated with Vv and area of mitochondria in SatMg in the control group and negatively in the schizophrenia group. Correlation coefficients between these parameters differed significantly between the groups. These results indicate disturbed SatMg-neuron interactions in the schizophrenia brain and suggest a key role of mitochondrial abnormalities in SatMg in these disturbances.

Multiple genes encoding mitochondrial ribosomes are downregulated in brain and blood samples of individuals with schizophrenia

OBJECTIVES

Schizophrenia is a chronic, debilitating mental disorder whose pathophysiology is complex and not fully understood. Numerous studies suggest mitochondrial dysfunction may contribute to the development of schizophrenia. While mitochondrial ribosomes (mitoribosomes) are essential for proper mitochondrial functioning, their gene expression levels have not been studied yet in schizophrenia.

METHODS

We performed a systematic meta-analysis of the expression of 81 mitoribosomes subunits encoding genes, integrating ten brain samples datasets of patients with schizophrenia compared to healthy controls (overall 422 samples, 211 schizophrenia, and 211 controls). We also performed a meta-analysis of their expression in blood, integrating two blood sample datasets (overall 90 samples, 53 schizophrenia, and 37 controls).

RESULTS

Multiple mitoribosomes subunits were significantly downregulated in brain samples (18 genes) and in blood samples (11 genes) of individuals with schizophrenia, where two showed significant downregulation in both brain and blood, MRPL4 and MRPS7.

CONCLUSIONS

Our results support the accumulating evidence of impaired mitochondrial activity in schizophrenia. While further research is needed to validate mitoribosomes' role as biomarkers, this direction has the potential to promote patients' stratification and personalised treatment for schizophrenia.

Schizophrenia-Like Psychotic Symptoms Associated to Leigh Syndrome

Introduction

Leigh syndrome (LS) is a mitochondrial disease characterized by subacute necrotizing encephalomyelopathy with an estimated incidence of 1:40,000 births. The comorbidity of psychotic symptoms noted in mitochondrial and psychiatric diseases has spurred interest in the effects of DNA mutations and psychiatric disorders. Case presentation. We report the case of a Tunisian 28-year-old male diagnosed with maternally inherited Leigh syndrome. He presented anxiety and auditory hallucinations, and he reported a vague, unsystematized delusion evolving since 6 months. Significant remission was observed at risperidone 3 mg/day. Discussion. The normality of explorations in our case raised the issue of the link between the two diseases, supporting the hypothesis that mitochondrial dysfunction maybe the primary origin of psychotic disorders.

Conclusion

The aim of our work is to study the relations between mitochondrial dysfunction and psychiatric symptoms. Further study of mitochondrial dysfunction in psychiatric disorders is expected to be useful for the development of cellular disease markers and new psychotropics.

Schizophrenia Synaptic Pathology and Antipsychotic Treatment in the Framework of Oxidative and Mitochondrial Dysfunction: Translational Highlights for the Clinics and Treatment

Schizophrenia is a worldwide mental illness characterized by alterations at dopaminergic and glutamatergic synapses resulting in global dysconnectivity within and between brain networks. Impairments in inflammatory processes, mitochondrial functions, energy expenditure, and oxidative stress have been extensively associated with schizophrenia pathophysiology. Antipsychotics, the mainstay of schizophrenia pharmacological treatment and all sharing the common feature of dopamine D2 receptor occupancy, may affect antioxidant pathways as well as mitochondrial protein levels and gene expression. Here, we systematically reviewed the available evidence on antioxidants' mechanisms in antipsychotic action and the impact of first- and second-generation compounds on mitochondrial functions and oxidative stress. We further focused on clinical trials addressing the efficacy and tolerability of antioxidants as an augmentation strategy of antipsychotic treatment. EMBASE, Scopus, and Medline/PubMed databases were interrogated. The selection process was conducted in respect of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Several mitochondrial proteins involved in cell viability, energy metabolism, and regulation of oxidative systems were reported to be significantly modified by antipsychotic treatment with differences between first- and second-generation drugs. Finally, antioxidants may affect cognitive and psychotic symptoms in patients with schizophrenia, and although the evidence is only preliminary, the results indicate that further studies are warranted.

Transcriptomic analyses reveal neuronal specificity of Leigh syndrome associated genes

Leigh syndrome is a rare, inherited, complex neurometabolic disorder with genetic and clinical heterogeneity. Features present in affected patients range from classical stepwise developmental regression to ataxia, seizures, tremor, and occasionally psychiatric manifestations. Currently, more than 100 monogenic causes of Leigh syndrome have been identified, yet the pathophysiology remains unknown. Here, we sought to determine the cellular specificity within the brain of all genes currently associated with Leigh syndrome. Further, we aimed to investigate potential genetic commonalities between Leigh syndrome and other disorders with overlapping clinical features. Enrichment of our target genes within the brain was evaluated with co-expression (CoExp) network analyses constructed using existing UK Brain Expression Consortium data. To determine the cellular specificity of the Leigh associated genes, we employed expression weighted cell type enrichment (EWCE) analysis of single-cell RNA-Seq data. Finally, CoExp network modules demonstrating enrichment of Leigh syndrome associated genes were then utilised for synaptic gene ontology analysis and heritability analysis. CoExp network analyses revealed that Leigh syndrome associated genes exhibit the highest levels of expression in brain regions most affected on MRI in affected patients. EWCE revealed significant enrichment of target genes in hippocampal and somatosensory pyramidal neurons and interneurons of the brain. Analysis of CoExp modules enriched with our target genes revealed preferential association with pre-synaptic structures. Heritability studies suggested some common enrichment between Leigh syndrome and Parkinson disease and epilepsy. Our findings suggest a primary mitochondrial dysfunction as the underlying basis of Leigh syndrome, with associated genes primarily expressed in neuronal cells.

The interplay of dopamine metabolism abnormalities and mitochondrial defects in the pathogenesis of schizophrenia

Dopamine (DA) is a major monoamine neurotransmitter in the brain and has essential roles in higher functions of the brain. Malfunctions of dopaminergic signaling have been implicated in various mental disorders such as addiction, attention deficit/hyperactivity disorder, Huntington's disease, Parkinson's disease (PD), and schizophrenia. The pathogenesis of PD and schizophrenia involves the interplay of mitochondrial defect and DA metabolism abnormalities. This article focuses on this issue in schizophrenia. It started with the introduction of metabolism, behavioral action, and physiology of DA, followed by reviewing evidence for malfunctions of dopaminergic signaling in patients with schizophrenia. Then it provided an overview of multiple facets of mitochondrial physiology before summarizing mitochondrial defects reported in clinical studies with schizophrenia patients. Finally, it discussed the interplay between DA metabolism abnormalities and mitochondrial defects and outlined some clinical studies showing effects of combination therapy of antipsychotics and antioxidants in treating patients with schizophrenia. The update and integration of these lines of information may advance our understanding of the etiology, pathogenesis, phenomenology, and treatment of schizophrenia.

Emerging roles of brain metabolism in cognitive impairment and neuropsychiatric disorders

Here we discuss the role of diverse environmental manipulations affecting cognition with special regard to psychiatric conditions. We present evidence supporting a direct causal correlation between the valence of the environmental stimulation and some psychopathological traits and how the environment influences brain structure and function with special regard to oxidative stress and mitochondrial activity. Increasing experimental evidence supports a role for mitochondrial dysfunctions in neuropsychiatric disorders. Brain mitochondria are considered crucial mediators of allostasis, that is the capability to adapt to stress via a complex interaction between the autonomic, metabolic, and immune systems to maintain cellular homeostasis. In this process, mitochondria act as highly dynamic integrators by sensing and transducing stressors into adaptation mechanisms via metabolic stress mediators, such as glucocorticoids and catecholamines. Alterations in cellular homeostasis induced by chronic stress are thought to predispose to disease by triggering the so-called "mitochondrial allostatic load". This process is characterized by functional and structural changes of the mitochondria, ultimately leading to oxidative stress, inflammation, mitochondrial DNA damage and apoptosis. In this review we discuss the role of diverse environmental manipulations to affect cognition with special regard to psychiatric conditions. How the environment influences brain structure and function, and the interactions between rearing conditions, oxidative stress and mitochondrial activity are fundamental questions that are still poorly understood. As will be discussed, increasing experimental evidence supports a role for mitochondrial dysfunctions in neuropsychiatric disorders. Brain mitochondria are considered crucial mediators of allostasis, that is the capability to adapt to stress via a complex interaction between the autonomic, metabolic, and immune systems to maintain cellular homeostasis. In this process, mitochondria act as highly dynamic integrators by sensing and transducing stressors into adaptation mechanisms via metabolic stress mediators, such as glucocorticoids and catecholamines. Alterations in cellular homeostasis induced by chronic stress are thought to predispose to disease by triggering the so-called "mitochondrial allostatic load". This process is characterized by functional and structural changes of the mitochondria, ultimately leading to oxidative stress, inflammation, mitochondrial DNA damage and apoptosis. The brain requires considerable mitochondrial reserve not only to sustain basal neuronal needs but a also to provide increasing energy demands during stress. Consistently with these high energetic requirements, it is reasonable to hypothesise that the brain is particularly vulnerable to mitochondrial defects. Thus, even subtle metabolic alterations might have a substantial impact on cognitive functions. Over the last decade, several experimental evidence supported the hypothesis that a suboptimal mitochondrial function, which could be of genetic origin or acquired following adverse life events, is a key vulnerability factor for stress-related psychopathologies. Chronic psychological stress is a major promoter of anxiety as well as of oxidative damage, as shown in several studies. Recent evidence from mouse models harbouring mutations in mitochondrial genes demonstrated the role of mitochondria in modulating the response to acute psychological stress. However, it has yet to be determined whether mitochondrial dysfunctions are the cause or the consequence of anxiety. In this review, we discuss how adverse psychosocial environments can impact mitochondrial bioenergetics at the molecular level and we gather evidence from several studies linking energy metabolism and stress resilience/vulnerability. Moreover, we review recent findings supporting that metabolic dysfunction can underlie deficits in complex social behaviours. As will be discussed, aberrations in mitochondrial functionality have been found in the nucleus accumbens of highly anxious mice and mediate low social competitiveness. In addition, alterations in sociability can be reversed by enhancing mitochondrial functions. Recent evidence also demonstrated that a specific mutation in mitochondrial DNA, previously linked to autism spectrum disorder, produces autistic endophenotypes in mice by altering respiration chain and reactive oxygen species (ROS) production. Finally, we discuss a "Negative Enrichment" model that can explain some of the psychopathological conditions relevant to humans. Evidence of a direct causal correlation of valence of environmental stimulation and psychopathological traits will be presented, and possible molecular mechanisms that focus on oxidative stress. Collectively, the findings described here have been achieved with a wide set of behavioural and cognitive tasks with translational validity. Thus, they will be useful for future work aimed to elucidate the fine metabolic alterations in psychopathologies and devise novel approaches targeting mitochondria to alleviate these conditions.

Mitochondrial Damage of Lymphocytes in Patients with Acute Relapse of Schizophrenia: A Correlational Study with Efficacy and Clinical Symptoms

OBJECTIVE

Accumulating evidence has demonstrated that schizophrenia is associated with mitochondrial and immune abnormalities. In this pilot case-control study, we investigated the level of mitochondrial impairment in lymphocytes in patients with acute relapse of schizophrenia and explored the correlation between the level of mitochondrial damage and symptoms or treatment response.

METHODS

Lymphocytic mitochondrial damage was detected using mitochondrial fluorescence staining and flow cytometry in 37 patients (at admission and discharge) and 24 controls. Clinical symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression Scale (CGI-S).

RESULTS

The levels of mitochondrial damage in CD3+ T, CD4+ T, and CD8+ T lymphocytes of the patients with schizophrenia at admission were significantly higher than those of the controls (p<0.05) and did not return to normal at discharge (p>0.05). The mitochondrial damage of T cells significantly improved at discharge for responsive patients only, as compared with that at admission (P<0.05). However, no significant difference was found in mitochondrial damage in CD19+ B cells between patients and healthy controls, or between admission and discharge (p>0.05). Furthermore, the reduction in mitochondrial damage of CD3, CD4, and CD8 lymphocytes was positively correlated with the reduction of the score of the PANSS positive scale at discharge (p<0.05), while no significant correlation was found between the level of mitochondrial damage in lymphocytes and the scores of PANSS and CGI-S.

CONCLUSION

Acute relapse of schizophrenia might be associated with higher levels of mitochondrial damage in peripheral blood T lymphocytes. The degree of recovery of mitochondrial impairment in the T cells may be used as a predictor of treatment response in schizophrenia. As this is a pilot study, the conclusion still needs further verification in large-scale studies.

The Perspectives of Early Diagnosis of Schizophrenia Through the Detection of Epigenomics-Based Biomarkers in iPSC-Derived Neurons

The lack of early diagnostic biomarkers for schizophrenia greatly limits treatment options that deliver therapeutic agents to affected cells at a timely manner. While previous schizophrenia biomarker research has identified various biological signals that are correlated with certain diseases, their reliability and practicality as an early diagnostic tool remains unclear. In this article, we discuss the use of atypical epigenetic and/or consequent transcriptional alterations (ETAs) as biomarkers of early-stage schizophrenia. Furthermore, we review the viability of discovering and applying these biomarkers through the use of cutting-edge technologies such as human induced pluripotent stem cell (iPSC)-derived neurons, brain models, and single-cell level analyses.

The role of mitochondria in the pathophysiology of schizophrenia: A critical review of the evidence focusing on mitochondrial complex one

There has been increasing interest in the role of mitochondrial dysfunction in the pathophysiology of schizophrenia. Mitochondrial complex one (MCI) dysfunction may represent a mechanism linking bioenergetic impairment with the alterations in dopamine signalling, glutamatergic dysfunction, and oxidative stress found in the disorder. New lines of evidence from novel approaches make it timely to review evidence for mitochondrial involvement in schizophrenia, with a specific focus on MCI. The most consistent findings in schizophrenia relative to controls are reductions in expression of MCI subunits in post-mortem brain tissue (Cohen's d> 0.8); reductions in MCI function in post-mortem brains (d> 0.7); and reductions in neural glucose utilisation (d= 0.3 to 0.6). Antipsychotics may affect glucose utilisation, and, at least in vitro, affect MC1. The findings overall are consistent with MCI dysfunction in schizophrenia, but also highlight the need for in vivo studies to determine the link between MCI dysfunction and symptoms in patients. If new imaging tools confirm MCI dysfunction in the disease, this could pave the way for new treatments targeting this enzyme.

Abnormal microglial reactivity in gray matter of the prefrontal cortex in schizophrenia

Microglial activation has been proposed to contribute to the pathogenesis of schizophrenia. The present study addressed the questions of whether microglial reactivity is involved in the course of schizophrenia and is associated with aging. Transmission electron microscopy and morphometry were applied to estimate microglial density and ultrastructural parameters in layer 5 of the prefrontal cortex (BA10) in postmortem 21 chronic schizophrenia and 20 healthy control cases. A significant increase in microglial density was found in the schizophrenia group (+20 %), in young group (≤50 y.o.), in shorter duration of disease (≤26 yrs.) group, in early age at onset of disease (≤ 21 y.o.) group as compared to controls (p < 0.05) and in young schizophrenia group as compared to both young and elderly (>50 y.o.) controls (p < 0.05). Volume fraction (Vv) of mitochondria was significantly lower and area of lipofuscin granules was significantly higher in young and elderly schizophrenia groups as compared to young and elderly controls. Vv of lipofuscin granules strongly positively correlated with age and duration of disease in the schizophrenia group. Vv and the number (N) of lipofuscin granules were higher in longer duration (>26 yrs.) group as compared to shorter duration group (p < 0.01). Vv and N of vacuoles were increased in longer duration group as compared to controls (p < 0.01). The study provides evidence for microgliosis associated with age, duration of disease and age at onset of disease, progressive dystrophy and accelerated aging of microglia in gray matter of the prefrontal cortex in schizophrenia.

Decreased Brain pH and Pathophysiology in Schizophrenia

Postmortem studies reveal that the brain pH in schizophrenia patients is lower than normal. The exact cause of this low pH is unclear, but increased lactate levels due to abnormal energy metabolism appear to be involved. Schizophrenia patients display distinct changes in mitochondria number, morphology, and function, and such changes promote anaerobic glycolysis, elevating lactate levels. pH can affect neuronal activity as H⁺ binds to numerous proteins in the nervous system and alters the structure and function of the bound proteins. There is growing evidence of pH change associated with cognition, emotion, and psychotic behaviors. Brain has delicate pH regulatory mechanisms to maintain normal pH in neurons/glia and extracellular fluid, and a change in these mechanisms can affect, or be affected by, neuronal activities associated with schizophrenia. In this review, we discuss the current understanding of the cause and effect of decreased brain pH in schizophrenia based on postmortem human brains, animal models, and cellular studies. The topic includes the factors causing decreased brain pH in schizophrenia, mitochondria dysfunction leading to altered energy metabolism, and pH effects on the pathophysiology of schizophrenia. We also review the acid/base transporters regulating pH in the nervous system and discuss the potential contribution of the major transporters, sodium hydrogen exchangers (NHEs), and sodium-coupled bicarbonate transporters (NCBTs), to schizophrenia.

Exploring the crosstalk of glycolysis and mitochondrial metabolism in psychiatric disorders and brain tumours

Dysfunction of metabolic pathways characterises a plethora of common pathologies and has emerged as an underlying hallmark of disease phenotypes. Here, we focus on psychiatric disorders and brain tumours and explore changes in the interplay between glycolysis and mitochondrial energy metabolism in the brain. We discuss alterations in glycolysis versus core mitochondrial metabolic pathways, such as the tricarboxylic acid cycle and oxidative phosphorylation, in major psychiatric disorders and brain tumours. We investigate potential common patterns of altered mitochondrial metabolism in different brain regions and sample types and explore how changes in mitochondrial number, shape and morphology affect disease-related manifestations. We also highlight the potential of pharmacologically targeting mitochondria to achieve therapeutic effects.

Schizophrenia-associated dysbindin modulates axonal mitochondrial movement in cooperation with p150glued

Mitochondrial movement in neurons is finely regulated to meet the local demand for energy and calcium buffering. Elaborate transport machinery including motor complexes is required to deliver and localize mitochondria to appropriate positions. Defects in mitochondrial transport are associated with various neurological disorders without a detailed mechanistic information. In this study, we present evidence that dystrobrevin-binding protein 1 (dysbindin), a schizophrenia-associated factor, plays a critical role in axonal mitochondrial movement. We observed that mitochondrial movement was impaired in dysbindin knockout mouse neurons. Reduced mitochondrial motility caused by dysbindin deficiency decreased the density of mitochondria in the distal part of axons. Moreover, the transport and distribution of mitochondria were regulated by the association between dysbindin and p150glued. Furthermore, altered mitochondrial distribution in axons led to disrupted calcium dynamics, showing abnormal calcium influx in presynaptic terminals. These data collectively suggest that dysbindin forms a functional complex with p150glued that regulates axonal mitochondrial transport, thereby affecting presynaptic calcium homeostasis.

Mitochondrial dysfunction in schizophrenia: With a focus on postmortem studies

Among the many brain abnormalities in schizophrenia are those related to mitochondrial functions such as oxidative stress, energy metabolism and synaptic efficacy. The aim of this paper is to provide a brief review of mitochondrial structure and function and then to present abnormalities in mitochondria in postmortem brain in schizophrenia with a focus on anatomy. Deficits in expression of various mitochondrial genes have been found in multiple schizophrenia cohorts. Decreased activity of complexes I and IV are prominent as well as abnormal levels of individual subunits that comprise the complexes of the electron transport chain. Ultrastructural studies have shown layer, input and cell specific decreases in mitochondria. In cortex, there are fewer mitochondria in axon terminals, neuronal somata of pyramidal neurons and oligodendrocytes in both grey and white matter. In the caudate and putamen mitochondrial number is linked with symptoms and symptom severity. While there is a decrease in the number of mitochondria in astrocytes, mitochondria are smaller in oligodendrocytes. In the nucleus accumbens and substantia nigra, mitochondria are similar in density, size and structural integrity in schizophrenia compared to controls. Mitochondrial production of ATP and calcium buffering are essential in maintaining synaptic strength and abnormalities in these processes could lead to decreased metabolism and defective synaptic activity. Abnormalities in mitochondria in oligodendrocytes might contribute to myelin pathology and underlie dysconnectivity in the brain. In schizophrenia, mitochondria are affected differentially depending on the brain region, cell type in which they reside, subcellular location, treatment status, treatment response and predominant symptoms.

Proton Magnetic Resonance Spectroscopy of N-acetyl Aspartate in Chronic Schizophrenia, First Episode of Psychosis and High-Risk of Psychosis: A Systematic Review and Meta-Analysis

N-acetyl-aspartate (NAA) is a readily measured marker of neuronal metabolism. Previous analyses in schizophrenia have shown NAA levels are low in frontal, temporal and thalamic regions, but may be underpowered to detect effects in other regions, in high-risk states and in first episode psychosis. We searched for magnetic resonance spectroscopy studies comparing NAA in chronic schizophrenia, first episode psychosis and high risk of psychosis to controls. 182 studies were included and meta-analysed using a random-effects model for each region and illness stage. NAA levels were significantly lower than controls in the frontal lobe [Hedge's g = -0.36, p < 0.001], hippocampus [-0.52, p < 0.001], temporal lobe [-0.35, p = 0.031], thalamus [-0.32, p = 0.012] and parietal lobe [-0.25, p = 0.028] in chronic schizophrenia, and lower than controls in the frontal lobe [-0.26, p = 0.002], anterior cingulate cortex [-0.24, p = 0.016] and thalamus [-0.28, p = 0.028] in first episode psychosis. NAA was lower in high-risk of psychosis in the hippocampus [-0.20, p = 0.049]. In schizophrenia, NAA alterations appear to begin in hippocampus, frontal cortex and thalamus, and extend later to many other regions.

Identification of rare and common variants in BNIP3L: a schizophrenia susceptibility gene

BACKGROUND

Schizophrenia is a chronic and severe mental disorder, and it has been predicted to be highly polygenic. Common SNPs located in or near BNIP3L were found to be genome-wide significantly associated with schizophrenia in recent genome-wide association studies. The purpose of our study is to investigate potential causal variants in BNIP3L gene.

RESULTS

We performed targeted sequencing for all exons and un-translated regions of BNIP3L gene among 1806 patients with schizophrenia and 998 healthy controls of Han Chinese origin. Three rare nonsynonymous mutations, BNIP3L (NM_004331): c.52A>G, c.167G>A and c.313A>T, were identified in schizophrenia cases, and two of them were newly reported. The frequencies of these rare nonsynonymous mutations were significantly different between schizophrenia cases and healthy controls. For the common variants, rs147389989 achieved significance in both allelic and genotypic distributions with schizophrenia. Rs1042992 and rs17310286 were significantly associated with schizophrenia in meta-analyses using PGC, CLOZUK, and our new datasets in this study.

CONCLUSIONS

Our findings provided further evidence that BNIP3L gene is a susceptibility gene of schizophrenia and revealed functional and potential causal mutations in BNIP3L. However, more functional validations are suggested to better understand the role of BNIP3L in the etiology of schizophrenia.

Dystrophy of Oligodendrocytes and Adjacent Microglia in Prefrontal Gray Matter in Schizophrenia

BACKGROUND

Some evidence support the notion that microglia activation in acute state of schizophrenia might contribute to damage of oligodendrocytes and myelinated fibers. Previously we found dystrophic changes of oligodendrocytes in prefrontal white matter in schizophrenia subjects displaying predominantly positive symptoms as compared to controls. The aim of the study was to verify whether microglial activation might contribute to dystrophic changes of oligodendrocytes in prefrontal gray matter in this clinical subgroup.

METHODS

Transmission electron microscopy and morphometry of microglia and adjacent oligodendrocytes were performed in layer 5 of the prefrontal cortex (BA10) in the schizophrenia subjects displaying predominantly positive symptoms (SPPS, n = 12), predominantly negative symptoms (SPNS, n = 9) and healthy controls (n = 20).

RESULTS

Qualitative study showed microglial activation and dystrophic alterations of microglia and oligodendrocytes adjacent to each other in both subgroups as compared to controls. A significant reduction in volume density (Vv) and the number (N) of mitochondria and an increase in N of lipofuscin granules were found in oligodendrocytes and adjacent microglia in both subgroups. Vv of lipofuscin granules, Vv and N of vacuoles of endoplasmic reticulum in microglia were increased significantly in the SPPS subgroup as compared to controls. In the SPPS subgroup Vv and N of mitochondria in microglia were correlated with N of vacuoles in microglia (r = -0.61, p < 0.05) and with Vv (r = 0.79, p < 0.01) and N (r = 0.59, p < 0.05) of mitochondria in oligodendrocytes. Vv of mitochondria in microglia was also correlated with Vv and N of vacuoles in oligodendrocytes in the SPPS subgroup (r = 0.76, p < 0.01). Area of nucleus of microglial cells was correlated negatively with age (r = -0.76, p < 0.01) and age at illness onset (r = -0.65, p < 0.05) in the SPPS subgroup. In the SPNS subgroup N of mitochondria in microglia was correlated with Vv of lipofuscin granules in oligodendrocytes (r = -0.9, p < 0.01). There were no significant correlations between these parameters in the control group.

DISCUSSION

Microglial dystrophy might contribute to oligodendrocyte dystrophy in the schizophrenia subjects with predominantly positive symptoms during relapse. Mitochondria in microglia and oligodendrocytes may be a target for treatment strategy of schizophrenia.

Neuron-specific deficits of bioenergetic processes in the dorsolateral prefrontal cortex in schizophrenia

Schizophrenia is a devastating illness that affects over 2 million people in the United States and costs society billions of dollars annually. New insights into the pathophysiology of schizophrenia are needed to provide the conceptual framework to facilitate development of new treatment strategies. We examined bioenergetic pathways in the dorsolateral prefrontal cortex (DLPFC) of subjects with schizophrenia and control subjects using western blot analysis, quantitative real-time polymerase chain reaction, and enzyme/substrate assays. Laser-capture microdissection-quantitative polymerase chain reaction was used to examine these pathways at the cellular level. We found decreases in hexokinase (HXK) and phosphofructokinase (PFK) activity in the DLPFC, as well as decreased PFK1 mRNA expression. In pyramidal neurons, we found an increase in monocarboxylate transporter 1 mRNA expression, and decreases in HXK1, PFK1, glucose transporter 1 (GLUT1), and GLUT3 mRNA expression. These results suggest abnormal bioenergetic function, as well as a neuron-specific defect in glucose utilization, in the DLPFC in schizophrenia.

Mitochondrial Involvement in Mental Disorders; Energy Metabolism, Genetic, and Environmental Factors

Mental disorders such as major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ) are generally characterized by a combination of abnormal thoughts, perceptions, emotions, behavior, and relationships with others. Multiple risk factors incorporating genetic and environmental susceptibility are associated with development of these disorders. Mitochondria have a central role in the energy metabolism, and the literature suggests energy metabolism abnormalities are widespread in the brains of subjects with MDD, BD, and SZ. Numerous studies have shown altered expressions of mitochondria-related genes in these mental disorders. In addition, environmental factors for these disorders, such as stresses, have been suggested to induce mitochondrial abnormalities. Moreover, animal studies have suggested that interactions of altered expression of mitochondria-related genes and environmental factors might be involved in mental disorders. Further investigations into interactions of mitochondrial abnormalities with environmental factors are required to elucidate of the pathogenesis of these mental disorders.

Proteostasis and Mitochondrial Role on Psychiatric and Neurodegenerative Disorders: Current Perspectives

Proteostasis involves processes that are fundamental for neural viability. Thus, protein misfolding and the formation of toxic aggregates at neural level, secondary to dysregulation of the conservative mechanisms of proteostasis, are associated with several neuropsychiatric conditions. It has been observed that impaired mitochondrial function due to a dysregulated proteostasis control system, that is, ubiquitin-proteasome system and chaperones, could also have effects on neurodegenerative disorders. We aimed to critically analyze the available findings regarding the neurobiological implications of proteostasis on the development of neurodegenerative and psychiatric diseases, considering the mitochondrial role. Proteostasis alterations in the prefrontal cortex implicate proteome instability and accumulation of misfolded proteins. Altered mitochondrial dynamics, especially in proteostasis processes, could impede the normal compensatory mechanisms against cell damage. Thereby, altered mitochondrial functions on regulatory modulation of dendritic development, neuroinflammation, and respiratory function may underlie the development of some psychiatric conditions, such as schizophrenia, being influenced by a genetic background. It is expected that with the increasing evidence about proteostasis in neuropsychiatric disorders, new therapeutic alternatives will emerge.

Defects in Bioenergetic Coupling in Schizophrenia

Synaptic neurotransmission relies on maintenance of the synapse and meeting the energy demands of neurons. Defects in excitatory and inhibitory synapses have been implicated in schizophrenia, likely contributing to positive and negative symptoms as well as impaired cognition. Recently, accumulating evidence has suggested that bioenergetic systems, important in both synaptic function and cognition, are abnormal in psychiatric illnesses such as schizophrenia. Animal models of synaptic dysfunction demonstrated endophenotypes of schizophrenia as well as bioenergetic abnormalities. We report findings on the bioenergetic interplay of astrocytes and neurons and discuss how dysregulation of these pathways may contribute to the pathogenesis of schizophrenia, highlighting metabolic systems as important therapeutic targets.

Magnetic Resonance Spectroscopy in Schizophrenia: Evidence for Glutamatergic Dysfunction and Impaired Energy Metabolism

In the past couple of decades, major efforts were made to increase reliability of metabolic assessments by magnetic resonance methods. Magnetic resonance spectroscopy (MRS) has been valuable for providing in vivo evidence and investigating biomarkers in neuropsychiatric disorders, namely schizophrenia. Alterations of glutamate and glutamine levels in brains of schizophrenia patients relative to healthy subjects are generally interpreted as markers of glutamatergic dysfunction. However, only a small fraction of MRS-detectable glutamate is involved in neurotransmission. Here we review and discuss brain metabolic processes that involve glutamate and that are likely to be implicated in neuropsychiatric disorders.

Mitochondrial Complex I Deficiency in Schizophrenia and Bipolar Disorder and Medication Influence

Subjects with schizophrenia (SZ) and bipolar disorder (BD) show decreased protein and transcript levels for mitochondrial complex I. In vitro results suggest antipsychotic and antidepressant drugs may be responsible. We measured complex I activity in BD, SZ, and controls and presence of antipsychotic and antidepressant medications, mitochondrial DNA (mtDNA) copy number, and the mtDNA "common deletion" in the brain. Complex I activity in the prefrontal cortex was decreased by 45% in SZ compared to controls (p = 0.02), while no significant difference was found in BD. Complex I activity was significantly decreased (p = 0.01) in pooled cases (SZ and BD) that had detectable psychotropic medications and drugs compared to pooled cases with no detectable levels. Subjects with age at onset in their teens and psychotropic medications showed decreased (p < 0.05) complex I activity compared to subjects with an adult age at onset. Both SZ and BD groups displayed significant increases (p < 0.05) in mtDNA copy number compared to controls; however, common deletion burden was not altered. Complex I deficiency is found in SZ brain tissue, and psychotropic medications may play a role in mitochondrial dysfunction. Studies of medication-free first-episode psychosis patients are needed to elucidate whether mitochondrial pathophysiology occurs independent of medication effects.

Mitochondrial roles of the psychiatric disease risk factor DISC1

Ion transport during neuronal signalling utilizes the majority of the brain's energy supply. Mitochondria are key sites for energy provision through ATP synthesis and play other important roles including calcium buffering. Thus, tightly regulated distribution and function of these organelles throughout the intricate architecture of the neuron is essential for normal synaptic communication. Therefore, delineating mechanisms coordinating mitochondrial transport and function is essential for understanding nervous system physiology and pathology. While aberrant mitochondrial transport and dynamics have long been associated with neurodegenerative disease, they have also more recently been linked to major mental illness including schizophrenia, autism and depression. However, the underlying mechanisms have yet to be elucidated, due to an incomplete understanding of the combinations of genetic and environmental factors contributing to these conditions. Consequently, the DISC1 gene has undergone intense study since its discovery at the site of a balanced chromosomal translocation, segregating with mental illness in a Scottish pedigree. The precise molecular functions of DISC1 remain elusive. Reported functions of DISC1 include regulation of intracellular signalling pathways, neuronal migration and dendritic development. Intriguingly, a role for DISC1 in mitochondrial homeostasis and transport is fast emerging. Therefore, a major function of DISC1 in regulating mitochondrial distribution, ATP synthesis and calcium buffering may be disrupted in psychiatric disease. In this review, we discuss the links between DISC1 and mitochondria, considering both trafficking of these organelles and their function, and how, via these processes, DISC1 may contribute to the regulation of neuronal behavior in normal and psychiatric disease states.

Postmortem studies on mitochondria in schizophrenia

The aim of this paper is to provide a brief review of mitochondrial structure as it relates to function and then present abnormalities in mitochondria in postmortem schizophrenia with a focus on ultrastructure. Function, morphology, fusion, fission, motility, ΔΨmem, ATP production, mitochondrial derived vesicles, and mitochondria-associated ER membranes will be briefly covered. Pathology in mitochondria has long been implicated in schizophrenia, as shown by genetic, proteomic, enzymatic and anatomical abnormalities. The cortex and basal ganglia will be reviewed. In the anterior cingulate cortex, the number of mitochondria per neuronal somata in layers 5/6 in schizophrenia is decreased by 43%. There are also fewer mitochondria in terminals forming axospinous synapses. In the caudate and putamen the number of mitochondria is abnormal in both glial cells and neurons in schizophrenia subjects, the extent of which depends on treatment, response and predominant lifetime symptoms. Treatment-responsive schizophrenia subjects had about a 40% decrease in the number of mitochondria per synapse in the caudate nucleus and putamen, while treatment resistant cases had normal values. A decrease in mitochondrial density in the neuropil distinguishes paranoid from undifferentiated schizophrenia. The appearance, size and density of mitochondria were normal in the nucleus accumbens. In the substantia nigra, COX subunits were affected in rostral regions. Mitochondrial hyperplasia occurs within axon terminals that synapse onto dopamine neurons, but mitochondria in dopamine neuronal somata are similar in size and number. In schizophrenia, mitochondria are differentially affected depending on the brain region, cell type, subcellular location, treatment status, treatment response and symptoms.

Schizophrenia-like symptoms in a patient with Leigh syndrome

Leigh syndrome is a mitochondrial disease characterized by subacute necrotizing encephalomyelopathy. Almost all cases of Leigh syndrome develop at infancy or early childhood and die within several years due to rapidly progressive muscle weakness and respiratory failure. Here, we present a rare case of a patient who developed Leigh syndrome associated with thiamine-responsive pyruvate dehydrogenase-complex deficiency at 2 years of age and has survived to adolescence through effective high dose thiamin therapy. At 15 years of age, the patient presented persecutory delusions and auditory hallucinations, suggesting an association between mitochondrial dysfunction and schizophrenia-like psychotic symptoms.

Metabolic pathways in the periphery and brain: Contribution to mental disorders?

The association between mental disorders and diabetes has a long history. Recent large-scale, well-controlled epidemiological studies confirmed a link between diabetes and psychiatric illnesses. The scope of this review is to summarize our current understanding of this relationship from a molecular perspective. We first discuss the potential contribution of diabetes-associated metabolic impairments to the etiology of mental conditions. Then, we focus on possible shared molecular risk factors and mechanisms. Simple comorbidity, shared susceptibility loci, and common pathophysiological processes in diabetes and mental illnesses have changed our traditional way of thinking about mental illness. We conclude that schizophrenia and affective disorders are not limited to an imbalance in dopaminergic and serotoninergic neurotransmission in the brain. They are also systemic disorders that can be considered, to some extent, as metabolic disorders.

Neuropsychiatric Features in Primary Mitochondrial Disease

Mitochondrial diseases are a clinically heterogeneous group of disorders that ultimately result from dysfunction of the mitochondrial respiratory chain. There is some evidence to suggest that mitochondrial dysfunction plays a role in neuropsychiatric illness; however, the data are inconclusive. This article summarizes the available literature published in the area of neuropsychiatric manifestations in both children and adults with primary mitochondrial disease, with a focus on autism spectrum disorder in children and mood disorders and schizophrenia in adults.

Disrupted-in-schizophrenia 1 (DISC1) and Syntaphilin collaborate to modulate axonal mitochondrial anchoring

In neuronal axons, the ratio of motile-to-stationary mitochondria is tightly regulated by neuronal activation, thereby meeting the need for local calcium buffering and maintaining the ATP supply. However, the molecular players and detailed regulatory mechanisms behind neuronal mitochondrial movement are not completely understood. Here, we found that neuronal activation-induced mitochondrial anchoring is regulated by Disrupted-in-schizophrenia 1 (DISC1), which is accomplished by functional association with Syntaphilin (SNPH). DISC1 deficiency resulted in reduced axonal mitochondrial movement, which was partially reversed by concomitant SNPH depletion. In addition, a SNPH deletion mutant lacking the sequence for interaction with DISC1 exhibited an enhanced mitochondrial anchoring effect than wild-type SNPH. Moreover, upon neuronal activation, mitochondrial movement was preserved by DISC1 overexpression, not showing immobilized response of mitochondria. Taken together, we propose that DISC1 in association with SNPH is a component of a modulatory complex that determines mitochondrial anchoring in response to neuronal activation.

Mitochondrial impairment, apoptosis and autophagy in a rat brain as immediate and long-term effects of perinatal phencyclidine treatment - influence of restraint stress

Phencyclidine (PCP) acts as a non-competitive antagonist of glutamatergic N-methyl-d-aspartate receptor. Its perinatal administration to rats causes pathophysiological changes that mimick some pathological features of schizophrenia (SCH). Numerous data indicate that abnormalities in mitochondrial structure and function could be associated with the development of SCH. Mitochondrial dysfunction could result in the activation of apoptosis and/or autophagy. The aim of this study was to assess immediate and long-term effects of perinatal PCP administration and acute restraint stress on the activity of respiratory chain enzymes, expression of apoptosis and autophagy markers and ultrastructural changes in the cortex and hippocampus of the rat brain. Six groups of rats were subcutaneously treated on 2nd, 6th, 9th and 12th postnatal days (P), with either PCP (10mg/kg) or saline (0.9% NaCl). One NaCl and one PCP group were sacrificed on P13, while other two NaCl and PCP groups were sacrificed on P70. The remaining two NaCl and PCP groups were subjected to 1h restraint stress prior sacrifice on P70. Activities of respiratory chain enzymes were assessed spectrophotometrically. Expression of caspase 3 and AIF as markers of apoptosis and Beclin 1, p62 and LC3, as autophagy markers, was assessed by Western blot. Morphological changes of cortical and hippocampal ultrastructure were determined by transmission electron microscopy. Immediate effects of perinatal PCP administration at P13 were increased activities of complex I in the hippocampus and cytochrome c oxidase (COX) in the cortex and hippocampus implying mitochondrial dysfunction. These changes were followed by increased expression of apoptotic markers. However the measurement of autophagy markers at this time point has revealed decrease of this process in cortex and the absence of changes in hippocampus. At P70 the activity of complex I was unchanged while COX activity was significantly decreased in cortex and increased in the hippocampus. Expressions of apoptotic markers were still significantly higher in PCP perinatally treated rats in all investigated structures, but the changes of autophagy markers have indicated increased level of autophagy also in both structures. Restraint stress on P70 has caused increase of COX activity both in NaCl and PCP perinatally treated rats, but this increase was lower in PCP group. Also, restraint stress resulted in decrease of apoptotic and increase of autophagy processes especially in the hippocampus of PCP perinatally treated group. The presence of apoptosis and autophagy in the brain was confirmed by transmission electron microscopy. In this study we have demonstrated for the first time the presence of autophagy in PCP model of SCH. Also, we have shown increased sensitivity of PCP perinatally treated rats to restraint stress, manifested in alterations of apoptotic and autophagy markers. The future studies are necessary to elucidate the role of mitochondria in the pathophysiology of SCH and putative significance for development of novel therapeutic strategies.

Comparative Pharmacology of Risperidone and Paliperidone

Antipsychotics, risperidone, and risperidone’s active metabolite, paliperidone (9-hydroxyrisperidone), are related molecules used for the treatment of schizophrenia and related disorders. Differences in receptor binding, 5-HT_2A/D₂ (serotonin/dopamine) binding ratios, and mitochondrial proteomics suggest that the effects of risperidone and paliperidone on neuronal firing, regulation of mitochondrial function, and movement are different. This review seeks to explore the most significant differences at the molecular level between risperidone and paliperidone, as reported in preclinical studies. Although risperidone shows higher affinity for 5-HT receptors, paliperidone does not fit this profile. Thus, the risperidone 5-HT_2A/D₂ binding ratio is significantly lower than the paliperidone 5-HT_2A/D₂ binding ratio. Paliperidone, similar to lithium and valproate, affects expression levels and phosphorylation of complex I and V proteins in synaptoneurosomal preparations of rat prefrontal cortex, suggesting that paliperidone behaves as a mood stabilizer. It is apparent that the presence of a hydroxyl group in the paliperidone molecule confers increased hydrophilicity to this drug compared with its parent, risperidone; thus, this contributes to differential effects on mitochondrial movement, protein expression, and phosphorylation. These differences are reflected in synaptic plasticity and neuronal firing and have only recently been implicated in the mechanisms of mitochondrial function and movement.

Pharmacological targeting of redox regulation systems as new therapeutic approach for psychiatric disorders: A literature overview

Redox dysregulation occurs following a disequilibrium between reactive oxygen species (ROS) producing and degrading systems, i.e. mitochondria, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and nitric oxide synthase (NOS) on one hand and the principal antioxidant system, the glutathione, on the other hand. Increasing recent evidence points towards a pathogenetic role of an altered redox state in the development of several mental disorders, such as anxiety, bipolar disorders, depression, psychosis, autism and post-traumaticstress disorders (PTSD). In this regard, pharmacological targeting of the redox state regulating systems in the brain has been proposed as an innovative and promising therapeutic approach for the treatment of these mental diseases. This review will summarize current knowledge obtained from both pre-clinical and clinical studies in order to descant "lights and shadows" of targeting pharmacologically both the producing and degrading reactive oxygen species (ROS) systems in psychiatric disorders.

Mitochondrial genome variations and functional characterization in Han Chinese families with schizophrenia

The relationship between mitochondrial DNA (mtDNA) variants and schizophrenia has been strongly debated. To test whether mtDNA variants are involved in schizophrenia in Han Chinese patients, we sequenced the entire mitochondrial genomes of probands from 11 families with a family history and maternal inheritance pattern of schizophrenia. Besides the haplogroup-specific variants, we found 11 nonsynonymous private variants, one rRNA variant, and one tRNA variant in 5 of 11 probands. Among the nonsynonymous private variants, mutations m.15395 A>G and m.8536 A>G were predicted to be deleterious after web-based searches and in silico program affiliated analysis. Functional characterization further supported the potential pathogenicity of the two variants m.15395 A>G and m.8536 A>G to cause mitochondrial dysfunction at the cellular level. Our results showed that mtDNA variants were actively involved in schizophrenia in some families with maternal inheritance of this disease.

Schizophrenia and Leigh syndrome, a simple comorbidity or the same etiopathogeny: about a case

Leigh syndrome is a mitochondrial encephalomyopathy that occurs due to "cytochrome c oxidase deficiency". Few psychiatric disorders have been defined that are associated with Leigh syndrome. The objective of this work is to study relations between mitochondrial dysfunction and psychiatric disorders. It was a 20 year old male patient, who received Modopar, for severe extra pyramidal symptoms caused by Leigh syndrome. He developed, four months ago, acute psychotic symptoms such as audio-visual hallucinations, persecution and mystic delirium. The cerebral MRI has shown signal abnormalities in central grey nucleus. The EEG recording and blood test were normal. The hypothesis of drug induced psychiatric disorders (Modopar) was possible. The evolution under atypical antipsychotic was only partial. In this case, the cerebrospinal fluid and lactate levels mean that mitochondria were not an overall explanation for these psychiatric disorders but may at least play a partial role. Psychiatric disorders may just be acomorbidity.

Distinctive transcriptome alterations of prefrontal pyramidal neurons in schizophrenia and schizoaffective disorder

Schizophrenia is associated with alterations in working memory that reflect dysfunction of dorsolateral prefrontal cortex (DLPFC) circuitry. Working memory depends on the activity of excitatory pyramidal cells in DLPFC layer 3 and, to a lesser extent, in layer 5. Although many studies have profiled gene expression in DLPFC gray matter in schizophrenia, little is known about cell-type-specific transcript expression in these two populations of pyramidal cells. We hypothesized that interrogating gene expression, specifically in DLPFC layer 3 or 5 pyramidal cells, would reveal new and/or more robust schizophrenia-associated differences that would provide new insights into the nature of pyramidal cell dysfunction in the illness. We also sought to determine the impact of other variables, such as a diagnosis of schizoaffective disorder or medication use at the time of death, on the patterns of gene expression in pyramidal neurons. Individual pyramidal cells in DLPFC layers 3 or 5 were captured by laser microdissection from 36 subjects with schizophrenia or schizoaffective disorder and matched normal comparison subjects. The mRNA from cell collections was subjected to transcriptome profiling by microarray followed by quantitative PCR validation. Expression of genes involved in mitochondrial (MT) or ubiquitin-proteasome system (UPS) functions were markedly downregulated in the patient group (P-values for MT-related and UPS-related pathways were <10(-7) and <10(-5), respectively). MT-related gene alterations were more prominent in layer 3 pyramidal cells, whereas UPS-related gene alterations were more prominent in layer 5 pyramidal cells. Many of these alterations were not present, or found to a lesser degree, in samples of DLPFC gray matter from the same subjects, suggesting that they are pyramidal cell specific. Furthermore, these findings principally reflected alterations in the schizophrenia subjects were not present or present to a lesser degree in the schizoaffective disorder subjects (diagnosis of schizoaffective disorder was the most significant covariate, P<10(-6)) and were not attributable to factors frequently comorbid with schizophrenia. In summary, our findings reveal expression deficits in MT- and UPS-related genes specific to layer 3 and/or layer 5 pyramidal cells in the DLPFC of schizophrenia subjects. These cell type-specific transcriptome signatures are not characteristic of schizoaffective disorder, providing a potential molecular-cellular basis of differences in clinical phenotypes.

Evidence of Mitochondrial Dysfunction within the Complex Genetic Etiology of Schizophrenia

Genetic evidence has supported the hypothesis that schizophrenia (SZ) is a polygenic disorder caused by the disruption in function of several or many genes. The most common and reproducible cellular phenotype associated with SZ is a reduction in dendritic spines within the neocortex, suggesting alterations in dendritic architecture may cause aberrant cortical circuitry and SZ symptoms. Here, we review evidence supporting a multifactorial model of mitochondrial dysfunction in SZ etiology and discuss how these multiple paths to mitochondrial dysfunction may contribute to dendritic spine loss and/or underdevelopment in some SZ subjects. The pathophysiological role of mitochondrial dysfunction in SZ is based upon genomic analyses of both the mitochondrial genome and nuclear genes involved in mitochondrial function. Previous studies and preliminary data suggest SZ is associated with specific alleles and haplogroups of the mitochondrial genome, and also correlates with a reduction in mitochondrial copy number and an increase in synonymous and nonsynonymous substitutions of mitochondrial DNA. Mitochondrial dysfunction has also been widely implicated in SZ by genome-wide association, exome sequencing, altered gene expression, proteomics, microscopy analyses, and induced pluripotent stem cell studies. Together, these data support the hypothesis that SZ is a polygenic disorder with an enrichment of mitochondrial targets.

Elevated Excitatory Input to the Nucleus Accumbens in Schizophrenia: A Postmortem Ultrastructural Study

The cause of schizophrenia (SZ) is unknown and no single region of the brain can be pinpointed as an area of primary pathology. Rather, SZ results from dysfunction of multiple neurotransmitter systems and miswiring between brain regions. It is necessary to elucidate how communication between regions is disrupted to advance our understanding of SZ pathology. The nucleus accumbens (NAcc) is a prime region of interest, where inputs from numerous brain areas altered in SZ are integrated. Aberrant signaling in the NAcc is hypothesized to cause symptoms of SZ, but it is unknown if these abnormalities are actually present. Electron microscopy was used to study the morphology of synaptic connections in SZ. The NAcc core and shell of 6 SZ subjects and 8 matched controls were compared in this pilot study. SZ subjects had a 19% increase in the density of asymmetric axospinous synapses (characteristic of excitatory inputs) in the core, but not the shell. Both groups had similar densities of symmetric synapses (characteristic of inhibitory inputs). The postsynaptic densities of asymmetric synapses had 22% smaller areas in the core, but not the shell. These results indicate that the core receives increased excitatory input in SZ, potentially leading to dysfunctional dopamine neurotransmission and cortico-striatal-thalamic stimulus processing. The reduced postsynaptic density size of asymmetric synapses suggests impaired signaling at these synapses. These findings enhance our understanding of the role the NAcc might play in SZ and the interaction of glutamatergic and dopaminergic abnormalities in SZ.

Cross-reactivity of Antibodies Directed to the Gram-Negative Bacterium Neisseria gonorrhoeae With Heat Shock Protein 60 and ATP-Binding Protein Correlates to Reduced Mitochondrial Activity in HIBCPP Choroid Plexus Papilloma Cells

Antibacterial antibodies can cause neurologic side-effects by cross-reactivity with cellular antigens. Here we investigated interactions of antibodies to Neisseria gonorrhoeae (α-NG) - maternal infections by which increases the offspring's risk for later psychosis-with HIBCPP cells, a cell culture model of choroid plexus epithelium. Immunocytochemistry and Western blotting with α-NG, revealed organelle-like intracellular staining in HIBCPP cells, and labelling of several immunoreactive bands in cellular protein. Two-dimensional Western blotting revealed several immunopositive spots, most prominent of which were identified by mass spectrometry as mitochondrially localized proteins heat shock protein 60 (Hsp60) and ATP-binding protein β-subunit (ATPB). Similarly α-NG interacted with commercial samples of these proteins as revealed by Western blotting. Three alternative methods (JC-1, Janus green and MTT staining) revealed α-NG to cause in HIBCPP cells a significant decrease in mitochondrial activity, which could be reverted by neuroleptic drugs. Immunoreactivity of α-NG with choroid plexus epithelium in human post mortem samples suggests in vivo relevance of these findings. Finally, distinctly different staining patterns of antibodies against Neisseria meningitidis (α-NM), confirmed antibody specificity. To our knowledge this is the first report that α-NG cross-reactivity with Hsp60 and ATPB impairs mitochondrial activity in choroid plexus epithelial cells, pathogenetic relevance of which needs further clarification.

The many roads to mitochondrial dysfunction in neuroimmune and neuropsychiatric disorders

BACKGROUND

Mitochondrial dysfunction and defects in oxidative metabolism are a characteristic feature of many chronic illnesses not currently classified as mitochondrial diseases. Examples of such illnesses include bipolar disorder, multiple sclerosis, Parkinson's disease, schizophrenia, depression, autism, and chronic fatigue syndrome.

DISCUSSION

While the majority of patients with multiple sclerosis appear to have widespread mitochondrial dysfunction and impaired ATP production, the findings in patients diagnosed with Parkinson's disease, autism, depression, bipolar disorder schizophrenia and chronic fatigue syndrome are less consistent, likely reflecting the fact that these diagnoses do not represent a disease with a unitary pathogenesis and pathophysiology. However, investigations have revealed the presence of chronic oxidative stress to be an almost invariant finding in study cohorts of patients afforded each diagnosis. This state is characterized by elevated reactive oxygen and nitrogen species and/or reduced levels of glutathione, and goes hand in hand with chronic systemic inflammation with elevated levels of pro-inflammatory cytokines.

SUMMARY

This paper details mechanisms by which elevated levels of reactive oxygen and nitrogen species together with elevated pro-inflammatory cytokines could conspire to pave a major road to the development of mitochondrial dysfunction and impaired oxidative metabolism seen in many patients diagnosed with these disorders.

Mitochondrial dysfunction in schizophrenia: an evolutionary perspective

Schizophrenia (SCZ) is a severe psychiatric illness with a lifetime prevalence of 0.4 %. A disturbance of energy metabolism has been suggested as part of the etiopathogenesis of the disorder. Several lines of evidence have proposed a connection between etiopathogenesis of SCZ and human brain evolution, which was characterized by an increase in the energy requirement, demanding a co-evolution of the mitochondrial system. Mitochondria are key players in brain energy homeostasis and multiple lines of evidence suggest that the system is disrupted in SCZ. In this review, we will describe the current knowledge on pathways/system involved in the human brain evolution as well as the main theories regarding the evolutionary origin of SCZ. We will furthermore discuss the role of mitochondria in the context of brain energy metabolism and its role in the etiopathogenesis of SCZ. Understanding SCZ in the context of human brain evolution opens a new perspective to elucidate pathophysiological mechanisms involved in the origin and/or portions of the complex symptomatology of this severe mental disorder.

Assessment of cytochrome C oxidase dysfunction in the substantia nigra/ventral tegmental area in schizophrenia

Perturbations in metabolism are a well-documented but complex facet of schizophrenia pathology. Optimal cellular performance requires the proper functioning of the electron transport chain, which is constituted by four enzymes located within the inner membrane of mitochondria. These enzymes create a proton gradient that is used to power the enzyme ATP synthase, producing ATP, which is crucial for the maintenance of cellular functioning. Anomalies in a single enzyme of the electron transport chain are sufficient to cause disruption of cellular metabolism. The last of these complexes is the cytochrome c oxidase (COX) enzyme, which is composed of thirteen different subunits. COX is a major site for oxidative phosphorylation, and anomalies in this enzyme are one of the most frequent causes of mitochondrial pathology. The objective of the present report was to assess if metabolic anomalies linked to COX dysfunction may contribute to substantia nigra/ventral tegmental area (SN/VTA) pathology in schizophrenia. We tested COX activity in postmortem SN/VTA from schizophrenia and non-psychiatric controls. We also tested the protein expression of key subunits for the assembly and activity of the enzyme, and the effect of antipsychotic medication on subunit expression. COX activity was not significantly different between schizophrenia and non-psychiatric controls. However, we found significant decreases in the expression of subunits II and IV-I of COX in schizophrenia. Interestingly, these decreases were observed in samples containing the entire rostro-caudal extent of the SN/VTA, while no significant differences were observed for samples containing only mid-caudal regions of the SN/VTA. Finally, rats chronically treated with antipsychotic drugs did not show significant changes in COX subunit expression. These findings suggest that COX subunit expression may be compromised in specific sub-regions of the SN/VTA (i.e. rostral regions), which may lead to a faulty assembly of the enzyme and a greater vulnerability to metabolic insult.

Subcortical modulation of attentional control by second-generation antipsychotics in first-episode psychosis

Psychotic disorders are characterized by significant deficits in attentional control, but the neurobiological mechanisms underlying these deficits early in the course of illness prior to extensive pharmacotherapy are not well understood. Moreover, little is known regarding the symptom and brain changes associated with amelioration of attentional impairments through antipsychotic pharmacotherapy. In this study 14 male patients experiencing a first-episode of psychosis with minimal prior antipsychotic treatment completed an attentional control task while undergoing functional magnetic resonance imaging at the onset of treatment with a second generation antipsychotic (risperidone or aripiprazole) in a double blind randomized clinical trial and then again following approximately 12 weeks of treatment. In addition, 14 age-, and performance-matched healthy male volunteers who were not treated completed the same task at a baseline timepoint and then again following 12 weeks. Patients showed significantly greater activation than healthy volunteers in the right globus pallidus, left thalamus, and right thalamus at the time of the baseline scan. Among patients there was a significant reduction in right globus pallidus blood-oxygen level dependent (BOLD) response following antipsychotic treatment that correlated significantly with improvement in response accuracy and reductions in thought disturbance. No changes in globus pallidus activation were observed in healthy volunteers over this time period. These preliminary findings suggest that improvement in attentional control and concomitant reductions in thought disturbance in first-episode psychosis may be associated with reductions in subcortical activity following administration of second-generation antipsychotics early in the course of illness. These findings have implications for understanding how changes in basal ganglia activity may be linked to improvements in attentional control through antipsychotics.

The mitochondrial genome and psychiatric illness

Psychiatric disorders are a leading cause of morbidity and mortality, yet their underlying pathophysiology remains unclear. Searches for a genetic cause of bipolar disorder, schizophrenia, and major depressive disorder have yielded inconclusive results. There is increasing interest in the possibility that defects in the mitochondrial genome may play an important role in psychiatric illness. We undertook a review of the literature investigating mitochondria and adult psychiatric disorders. MEDLINE, PsycINFO, and EMBASE were searched from their inception through September 2011, and the reference lists of identified articles were reviewed for additional studies. While multiple lines of evidence, including clinical, genetic, ultrastructural, and biochemical studies, support the involvement of mitochondria in the pathophysiology of psychiatric illness, many studies have methodological limitations and their findings have not been replicated. Clinical studies suggest that psychiatric features can be prominent, and the presenting features of mitochondrial disorders. There is limited but inconsistent evidence for the involvement of mitochondrial DNA haplogroups and mitochondria-related nuclear gene polymorphisms, and for mitochondrial ultrastructural and biochemical abnormalities in psychiatric illness. The current literature suggests that mitochondrial dysfunction and mitochondrial genetic variations may play an important role in psychiatric disorders, but additional methodologically rigorous and adequately powered studies are needed before definitive conclusions can be drawn.

Normobaric hyperoxia treatment of schizophrenia

Several studies of normobaric hyperoxia in neurological conditions have found positive results. The impaired energy metabolism due to mitochondrial dysfunction and frontal lobe hypofunction in schizophrenia might be improved by increasing O2 supply to the brain. Normobaric hyperoxia may be a potential treatment for schizophrenia. Participants in this study, outpatients with chronic schizophrenia and inhabitants of community-based psychiatric institutions (hostels), underwent baseline psychiatric/cognitive assessment and were randomly assigned to either a treatment intervention of oxygen-enriched air inhalation (normobaric hyperoxia of 40% fraction of inspired oxygen) or regular air inhalation (21% fraction of inspired oxygen), through a nasal tube, for 4 weeks. Patients were given the air/oxygen inhalations during the night (mainly while sleeping) for at least 7 hours a night. After completing 4 weeks of treatment, patients were switched (crossed over) to the other treatment intervention. Fifteen patients completed the entire study. Five additional patients completed phase A only. There was significant improvement in total Positive and Negative Symptoms Scale score of patients who received oxygen compared with the control group. There were positive effects of oxygen on memory and attention in neuropsychological performance tests. The effect size is small despite the statistical significance, but the patient group was extremely chronic and severely impaired. These results are a proof of concept, and normobaric hyperoxia should be studied in patients with milder forms of the illness and earlier in the course of illness.

Impaired mitochondrial function in psychiatric disorders

Major psychiatric illnesses such as mood disorders and schizophrenia are chronic, recurrent mental illnesses that affect the lives of millions of individuals. Although these disorders have traditionally been viewed as 'neurochemical diseases', it is now clear that they are associated with impairments of synaptic plasticity and cellular resilience. Although most patients with these disorders do not have classic mitochondrial disorders, there is a growing body of evidence to suggest that impaired mitochondrial function may affect key cellular processes, thereby altering synaptic functioning and contributing to the atrophic changes that underlie the deteriorating long-term course of these illnesses. Enhancing mitochondrial function could represent an important avenue for the development of novel therapeutics and also presents an opportunity for a potentially more efficient drug-development process.

Molecular links between mitochondrial dysfunctions and schizophrenia

Schizophrenia is a complex neuropsychiatric disorder with both neurochemical and neurodevelopmental components in the pathogenesis. Growing pieces of evidence indicate that schizophrenia has pathological components that can be attributable to the abnormalities of mitochondrial function, which is supported by the recent finding suggesting mitochondrial roles for Disrupted-in-Schizophrenia 1 (DISC1). In this minireview, we briefly summarize the current understanding of the molecular links between mitochondrial dysfunctions and the pathogenesis of schizophrenia, covering recent findings from human genetics, functional genomics, proteomics, and molecular and cell biological approaches.