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

Positive and negative schizotypy personality traits are lower in individuals on ketogenic diet in a non-clinical sample

Schizotypal personality comprises traits such as odd beliefs, perceptual abnormalities, and social difficulties; these traits are distributed throughout the general population. While not meeting the clinical threshold for schizophrenia or schizotypal personality disorder, schizotypal personality traits still provide insights for understanding early clinical risk factors. Ketogenic diet reportedly reduces psychotic symptoms in preclinical and clinical studies. Therefore, we investigated whether ketogenic diet is associated with lower schizotypal traits in the general population. Participants following a ketogenic or other diet were recruited using opportunity sampling. Individuals completed a survey investigating general demographic, socioeconomic, health, diet and lifestyle questions, followed by the Schizotypal Personality Questionnaire - Brief Revised version (SPQ-BR). We found that individuals following a ketogenic diet (n = 118) had lower ideas of reference, magical thinking, suspiciousness, unusual perceptions, constricted affect, social anxiety scores, cognitive (positive) perceptual scores, interpersonal (negative) scores and total SPQ-BR compared to individuals on the other diets (n = 139). Magical thinking, constricted affect, social anxiety, cognitive perceptual, interpersonal scores and total SPQ-BR scores remained significant when we controlled for body mass index (BMI) and age. Disorganised features were not influenced by ketogenic diet. The longer individuals adhered to a ketogenic diet the lower their positive and negative schizotypy traits. These findings highlight that ketogenic diet is associated with lower non-clinical schizotypal personality traits. Our results suggest that ketogenic diet might have potential prophylactic properties for individuals at-risk for psychosis.

Expression of WNT Signaling Genes in the Dorsolateral Prefrontal Cortex in Schizophrenia

Gene expression alterations in postmortem schizophrenia tissue are well-documented and are influenced by genetic, medication, and epigenetic factors. The Wingless/Integrated (WNT) signaling pathway, critical for cell growth and development, is involved in various cellular processes including neurodevelopment and synaptic plasticity. Despite its importance, WNT signaling remains understudied in schizophrenia, a disorder characterized by metabolic and bioenergetic defects in cortical regions. In this study, we examined the gene expression of 10 key WNT signaling pathway transcripts: IQGAP1, CTNNβ1, GSK3β, FOXO1, LRP6, MGEA5, TCF4, βTRC, PPP1Cβ, and DVL2 in the dorsolateral prefrontal cortex (DLPFC) using postmortem tissue from schizophrenia subjects (n = 20, 10 males, 10 females) compared to age, pH, and postmortem interval (PMI)-matched controls (n = 20, 10 males, 10 females). Employing the R-shiny application Kaleidoscope, we conducted in silico "lookup" studies from published transcriptomic datasets to examine cell- and region-level expression of these WNT genes. In addition, we investigated the impact of antipsychotics on the mRNA expression of the WNT genes of interest in rodent brain transcriptomic datasets. Our findings revealed no significant changes in region-level WNT transcript expression; however, analyses of previously published cell-level datasets indicated alterations in WNT transcript expression and antipsychotic-specific modulation of certain genes. These results suggest that WNT signaling transcripts may be variably expressed at the cellular level and influenced by antipsychotic treatment, providing novel insights into the role of WNT signaling in the pathophysiology of schizophrenia.

Progress in The Research of Lactate Metabolism Disruption And Astrocyte-Neuron Lactate Shuttle Impairment in Schizophrenia: A Comprehensive Review

Schizophrenia (SCZ) is a complex neuropsychiatric disorder widely recognized for its impaired bioenergy utilization. The astrocyte-neuron lactate shuttle (ANLS) plays a critical role in brain energy supply. Recent studies have revealed abnormal lactate metabolism in SCZ, which is associated with mitochondrial dysfunction, tissue hypoxia, gastric acid retention, oxidative stress, neuroinflammation, abnormal brain iron metabolism, cerebral white matter hypermetabolic activity, and genetic susceptibility. Furthermore, astrocytes, neurons, and glutamate abnormalities are prevalent in SCZ with abnormal lactate metabolism, which are essential components for maintaining ANLS in the brain. Therefore, an in-depth study of the pathophysiological mechanisms of ANLS in SCZ with abnormal lactate metabolism will contribute to a better understanding of the pathogenesis of SCZ and provide new ideas and approaches for the diagnosis and treatment of SCZ.

The Potential Role of the Ketogenic Diet in Serious Mental Illness: Current Evidence, Safety, and Practical Advice

The ketogenic diet (KD) is a high-fat, low-carbohydrate diet that mimics the physiological state of fasting. The potential therapeutic effects in many chronic conditions have led to the gaining popularity of the KD. The KD has been demonstrated to alleviate inflammation and oxidative stress, modulate the gut microbiota community, and improve metabolic health markers. The modification of these factors has been a potential therapeutic target in serious mental illness (SMI): bipolar disorder, major depressive disorder, and schizophrenia. The number of clinical trials assessing the effect of the KD on SMI is still limited. Preliminary research, predominantly case studies, suggests potential therapeutic effects, including weight gain reduction, improved carbohydrate and lipid metabolism, decrease in disease-related symptoms, increased energy and quality of life, and, in some cases, changes in pharmacotherapy (reduction in number or dosage of medication). However, these findings necessitate further investigation through larger-scale clinical trials. Initiation of the KD should occur in a hospital setting and with strict care of a physician and dietitian due to potential side effects of the diet and the possibility of exacerbating adverse effects of pharmacotherapy. An increasing number of ongoing studies examining the KD's effect on mental disorders highlights its potential role in the adjunctive treatment of SMI.

Neuronal alterations in AKT isotype expression in schizophrenia

Schizophrenia is characterized by substantial alterations in brain function, and previous studies suggest insulin signaling pathways, particularly involving AKT, are implicated in the pathophysiology of the disorder. This study demonstrates elevated mRNA expression of AKT1-3 in neurons from schizophrenia subjects, contrary to unchanged or diminished total AKT protein expression reported in previous postmortem studies, suggesting a potential decoupling of transcript and protein levels. Sex-specific differential AKT activity was observed, indicating divergent roles in males and females with schizophrenia. Alongside AKT, upregulation of PDPK1, a critical component of the insulin signaling pathway, and several protein phosphatases known to regulate AKT were detected. Moreover, enhanced expression of the transcription factor FOXO1, a regulator of glucose metabolism, hints at possible compensatory mechanisms related to insulin signaling dysregulation. Findings were largely independent of antipsychotic medication use, suggesting inherent alterations in schizophrenia. These results highlight the significance of AKT and related signaling pathways in schizophrenia, proposing that these changes might represent a compensatory response to a primary defect of conical insulin signaling pathways. This research underscores the need for a detailed understanding of these signaling pathways for the development of effective therapeutic strategies.

Glucose dysregulation in antipsychotic-naive first-episode psychosis: in silico exploration of gene expression signatures

Antipsychotic (AP)-naive first-episode psychosis (FEP) patients display early dysglycemia, including insulin resistance and prediabetes. Metabolic dysregulation may therefore be intrinsic to psychosis spectrum disorders (PSDs), independent of the metabolic effects of APs. However, the potential biological pathways that overlap between PSDs and dysglycemic states remain to be identified. Using meta-analytic approaches of transcriptomic datasets, we investigated whether AP-naive FEP patients share overlapping gene expression signatures with non-psychiatrically ill early dysglycemia individuals. We meta-analyzed peripheral transcriptomic datasets of AP-naive FEP patients and non-psychiatrically ill early dysglycemia subjects to identify common gene expression signatures. Common signatures underwent pathway enrichment analysis and were then used to identify potential new pharmacological compounds via Integrative Library of Integrated Network-Based Cellular Signatures (iLINCS). Our search results yielded 5 AP-naive FEP studies and 4 early dysglycemia studies which met inclusion criteria. We discovered that AP-naive FEP and non-psychiatrically ill subjects exhibiting early dysglycemia shared 221 common signatures, which were enriched for pathways related to endoplasmic reticulum stress and abnormal brain energetics. Nine FDA-approved drugs were identified as potential drug treatments, of which the antidiabetic metformin, the first-line treatment for type 2 diabetes, has evidence to attenuate metabolic dysfunction in PSDs. Taken together, our findings support shared gene expression changes and biological pathways associating PSDs with dysglycemic disorders. These data suggest that the pathobiology of PSDs overlaps and potentially contributes to dysglycemia. Finally, we find that metformin may be a potential treatment for early metabolic dysfunction intrinsic to PSDs.

Adenosine Receptor mRNA Expression in Frontal Cortical Neurons in Schizophrenia

Schizophrenia is a devastating neuropsychiatric disorder associated with the dysregulation of glutamate and dopamine neurotransmitter systems. The adenosine system is an important neuroregulatory system in the brain that modulates glutamate and dopamine signaling via the ubiquitously expressed adenosine receptors; however, adenosine A1 and A2A receptor (A1R and A2AR) mRNA expression is poorly understood in specific cell subtypes in the frontal cortical brain regions implicated in this disorder. In this study, we assayed A1R and A2AR mRNA expression via qPCR in enriched populations of pyramidal neurons, which were isolated from postmortem anterior cingulate cortex (ACC) tissue from schizophrenia (n = 20) and control (n = 20) subjects using laser microdissection (LMD). A1R expression was significantly increased in female schizophrenia subjects compared to female control subjects (t(13) = -4.008, p = 0.001). A1R expression was also significantly decreased in female control subjects compared to male control subjects, suggesting sex differences in basal A1R expression (t(17) = 2.137, p = 0.047). A significant, positive association was found between dementia severity (clinical dementia rating (CDR) scores) and A2AR mRNA expression (Spearman's r = 0.424, p = 0.009). A2AR mRNA expression was significantly increased in unmedicated schizophrenia subjects, suggesting that A2AR expression may be normalized by chronic antipsychotic treatment (F(1,14) = 9.259, p = 0.009). Together, these results provide novel insights into the neuronal expression of adenosine receptors in the ACC in schizophrenia and suggest that receptor expression changes may be sex-dependent and associated with cognitive decline in these subjects.

Activity of Protein Kinase A in the Frontal Cortex in Schizophrenia

Schizophrenia is a serious cognitive disorder characterized by disruptions in neurotransmission, a process requiring the coordination of multiple kinase-mediated signaling events. Evidence suggests that the observed deficits in schizophrenia may be due to imbalances in kinase activity that propagate through an intracellular signaling network. Specifically, 3'-5'-cyclic adenosine monophosphate (cAMP)-associated signaling pathways are coupled to the activation of neurotransmitter receptors and modulate cellular functions through the activation of protein kinase A (PKA), an enzyme whose function is altered in the frontal cortex in schizophrenia. In this study, we measured the activity of PKA in human postmortem anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) tissue from schizophrenia and age- and sex-matched control subjects. No significant differences in PKA activity were observed in male and female individuals in either brain region; however, correlation analyses indicated that PKA activity in the ACC may be influenced by tissue pH in all subjects and by age and tissue pH in females. Our data provide novel insights into the function of PKA in the ACC and DLPFC in schizophrenia.

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.

Shotgun metagenomics reveals abnormal short-chain fatty acid-producing bacteria and glucose and lipid metabolism of the gut microbiota in patients with schizophrenia

Evidence has shown that the gut microbiota is closely related to the pathogenesis of schizophrenia, but temporal changes in the gut microbiota of patients with schizophrenia (SZ) during treatment remain unclear. Here, to evaluate temporal changes in the gut microbiota in schizophrenia, we performed whole-genome shotgun metagenomics on fecal samples from 36 healthy controls (HCs) and 19 baseline-period patients, and followed up with patients upon treatment. Compared to that in HCs, beta diversity in SZ was significantly distinct. The genera Bacteroides, Prevotella and Clostridium were the top 3 altered genera between SZ and HCs, and the Bacteroides-Prevotella ratio was significantly increased in SZ. Thirty-three percent of differentially abundant species were short-chain fatty acid (SCFA)-producing bacteria. Functional analysis showed that glucose and lipid metabolism of the gut microbiota was decreased in SZ compared with those in HCs. The abundances of two rate-limiting enzymes in glucose and lipid metabolism, phosphofructokinase (PFK) and acetyl-CoA carboxylase (ACC), were significantly decreased in SZ, and differentially abundant metabolism-related enzymes were significantly associated with SCFA-producing bacteria. Next, we found that the abundance of SCFA-producing bacteria also changed after treatment and that Clostridium was significantly negatively correlated with the total positive and negative syndrome scale (PANSS) score in patients. Functional analysis showed that glycoside hydrolase family 30 incrementally increased in abundance during treatment and were significantly associated with SCFA-producing bacteria. Our findings help to provide evidence for the role of gut microbiota in the occurrence and development of schizophrenia.

Exploring the key factors of schizophrenia relapse by integrating LC-MS/1H NMR metabolomics and weighted correlation network analysis

BACKGROUND

Lack of comprehending key factors of schizophrenia relapse has impeded its effective treatment, indicating that the mechanism clarification and available intervention of schizophrenia relapse required further amelioration.

METHOD

Based on the integration of LC-MS and ¹H NMR metabolomics, a weighted correlation network was established to screen pivotal factors of accelerating schizophrenia relapse. Then, the cluster most correlated with schizophrenia relapse was explored, and the biological function of cluster was investigated. Next, the key biomarker related to schizophrenia relapse was obtained through multiple algorithms. Moreover, the Lilikoi algorithm and correlation analysis were implemented to reveal the association between key biomarker and schizophrenia relapse.

RESULT

Results showed that 458 different forms of metabolites were identified for structuring the weighted correlation network. The module-trait correlation indicated that the turquoise module was the most highly correlated with schizophrenia relapse. Further, network analysis revealed that, in turquoise module, cluster 1 composed of 139 metabolites (involved in lipid metabolism and energy metabolism) was the most important subnetwork relevant to schizophrenia relapse. Finally, phenylalanylphenylalanine was recommended as the key biomarker related to schizophrenia relapse. Moreover, the correlation analysis indicated that phenylalanylphenylalanine might affect the progression of schizophrenia by intervening in energy metabolism.

CONCLUSION

In summary, critical factors of schizophrenia relapse have been revealed in our research, expounding the schizophrenia progression more systemically, which could shed some light on improving the intervention of schizophrenia relapse.

A bioinformatic inquiry of the EAAT2 interactome in postmortem and neuropsychiatric datasets

Altered expression and localization of the glutamate transporter EAAT2 is found in schizophrenia and other neuropsychiatric (major depression, MDD) and neurological disorders (amyotrophic lateral sclerosis, ALS). However, the EAAT2 interactome, the network of proteins that physically or functionally interact with EAAT2 to support its activity, has yet to be characterized in severe mental illness. We compiled a list of "core" EAAT2 interacting proteins. Using Kaleidoscope, an R-shiny application, we data mined publically available postmortem transcriptome datasets to determine whether components of the EAAT2 interactome are differentially expressed in schizophrenia and, using Reactome, identify which interactome-associated biological pathways are altered. Overall, these "look up" studies highlight region-specific, primarily frontal cortex (dorsolateral prefrontal cortex and anterior cingulate cortex), changes in the EAAT2 interactome and implicate altered metabolism pathways in schizophrenia. Pathway analyses also suggest that perturbation of components of the EAAT2 interactome in animal models of antipsychotic administration impact metabolism. Similar changes in metabolism pathways are seen in ALS, in addition to altered expression of many components of the EAAT2 interactome. However, although EAAT2 expression is altered in a postmortem MDD dataset, few other components of the EAAT2 interactome are changed. Thus, "look up" studies suggest region- and disease-relevant biological pathways related to the EAAT2 interactome that implicate glutamate reuptake perturbations in schizophrenia, while providing a useful tool to exploit "omics" datasets.

Functional impairment of cortical AMPA receptors in schizophrenia

Clinical and preclinical studies suggest that some of the behavioral alterations observed in schizophrenia (SZ) may be mechanistically linked to synaptic dysfunction of glutamatergic signaling. Recent genetic and proteomic studies suggest alterations of cortical glutamate receptors of the AMPA-type (AMPARs), which are the predominant ligand-gated ionic channels of fast transmission at excitatory synapses. The impact of gene and protein alterations on the electrophysiological activity of AMPARs is not known in SZ. In this proof of principle work, using human postmortem brain synaptic membranes isolated from the dorsolateral prefrontal cortex (DLPFC), we combined electrophysiological analysis from microtransplanted synaptic membranes (MSM) with transcriptomic (RNA-Seq) and label-free proteomics data in 10 control and 10 subjects diagnosed with SZ. We observed in SZ a reduction in the amplitude of AMPARs currents elicited by kainate, an agonist of AMPARs that blocks the desensitization of the receptor. This reduction was not associated with protein abundance but with a reduction in kainate's potency to activate AMPARs. Electrophysiologically-anchored dataset analysis (EDA) was used to identify synaptosomal proteins that linearly correlate with the amplitude of the AMPARs responses, gene ontology functional annotations were then used to determine protein-protein interactions. Protein modules associated with positive AMPARs current increases were downregulated in SZ, while protein modules that were upregulated in SZ were associated with decreased AMPARs currents. Our results indicate that transcriptomic and proteomic alterations, frequently observed in the DLPFC in SZ, converge at the synaptic level producing a functional electrophysiological impairment of AMPARs.

Gene Enrichment Analysis of Astrocyte Subtypes in Psychiatric Disorders and Psychotropic Medication Datasets

Astrocytes have many important functions in the brain, but their roles in psychiatric disorders and their responses to psychotropic medications are still being elucidated. Here, we used gene enrichment analysis to assess the relationships between different astrocyte subtypes, psychiatric diseases, and psychotropic medications (antipsychotics, antidepressants and mood stabilizers). We also carried out qPCR analyses and "look-up" studies to assess the chronic effects of these drugs on astrocyte marker gene expression. Our bioinformatic analysis identified gene enrichment of different astrocyte subtypes in psychiatric disorders. The highest level of enrichment was found in schizophrenia, supporting a role for astrocytes in this disorder. We also found differential enrichment of astrocyte subtypes associated with specific biological processes, highlighting the complex responses of astrocytes under pathological conditions. Enrichment of protein phosphorylation in astrocytes and disease was confirmed by biochemical analysis. Analysis of LINCS chemical perturbagen gene signatures also found that kinase inhibitors were highly discordant with astrocyte-SCZ associated gene signatures. However, we found that common gene enrichment of different psychotropic medications and astrocyte subtypes was limited. These results were confirmed by "look-up" studies and qPCR analysis, which also reported little effect of psychotropic medications on common astrocyte marker gene expression, suggesting that astrocytes are not a primary target of these medications. Conversely, antipsychotic medication does affect astrocyte gene marker expression in postmortem schizophrenia brain tissue, supporting specific astrocyte responses in different pathological conditions. Overall, this study provides a unique view of astrocyte subtypes and the effect of medications on astrocytes in disease, which will contribute to our understanding of their role in psychiatric disorders and offers insights into targeting astrocytes therapeutically.

An Integrative Analysis of Identified Schizophrenia-Associated Brain Cell Types and Gene Expression Changes

Schizophrenia (SCZ) is a severe mental disorder that may result in hallucinations, delusions, and extremely disordered thinking. How each cell type in the brain contributes to SCZ occurrence is still unclear. Here, we leveraged the human dorsolateral prefrontal cortex bulk RNA-seq data, then used the RNA-seq deconvolution algorithm CIBERSORTx to generate SCZ brain single-cell RNA-seq data for a comprehensive analysis to understand SCZ-associated brain cell types and gene expression changes. Firstly, we observed that the proportions of brain cell types in SCZ differed from normal samples. Among these cell types, astrocyte, pericyte, and PAX6 cells were found to have a higher proportion in SCZ patients (astrocyte: SCZ = 0.163, control = 0.145, P.adj = 4.9 × 10^-4, effect size = 0.478; pericyte: SCZ = 0.057, control = 0.066, P.adj = 1.1 × 10^-4, effect size = 0.519; PAX6: SCZ = 0.014, control = 0.011, P.adj = 0.014, effect size = 0.377), while the L5/6_IT_CAR3 cells and LAMP5 cells are the exact opposite (L5/6_IT_Car3: SCZ = 0.102, control = 0.108, P.adj = 0.016, effect size = 0.369; LAMP5: SCZ = 0.057, control = 0.066, P.adj = 2.2 × 10^-6, effect size = 0.617). Next, we investigated gene expression in cell types and functional pathways in SCZ. We observed chemical synaptic transmission dysregulation in two types of GABAergic neurons (PVALB and LAMP5), and immune reaction involvement in GABAergic neurons (SST) and non-neuronal cell types (endothelial and oligodendrocyte). Furthermore, we observed that some differential expression genes from bulk RNA-seq displayed cell-type-specific abnormalities in the expression of molecules in SCZ. Finally, the cell types with the SCZ-related transcriptomic changes could be considered to belong to the same module since we observed two major similar coordinated transcriptomic changes across these cell types. Together, our results offer novel insights into cellular heterogeneity and the molecular mechanisms underlying SCZ.

Treatment of cancer with antipsychotic medications: Pushing the boundaries of schizophrenia and cancer

Over a century ago, the phenothiazine dye, methylene blue, was discovered to have both antipsychotic and anti-cancer effects. In the 20th-century, the first phenothiazine antipsychotic, chlorpromazine, was found to inhibit cancer. During the years of elucidating the pharmacology of the phenothiazines, reserpine, an antipsychotic with a long historical background, was likewise discovered to have anti-cancer properties. Research on the effects of antipsychotics on cancer continued slowly until the 21st century when efforts to repurpose antipsychotics for cancer treatment accelerated. This review examines the history of these developments, and identifies which antipsychotics might treat cancer, and which cancers might be treated by antipsychotics. The review also describes the molecular mechanisms through which antipsychotics may inhibit cancer. Although the overlap of molecular pathways between schizophrenia and cancer have been known or suspected for many years, no comprehensive review of the subject has appeared in the psychiatric literature to assess the significance of these similarities. This review fills that gap and discusses what, if any, significance the similarities have regarding the etiology of schizophrenia.

Schizophrenia: a disorder of broken brain bioenergetics

A substantial and diverse body of literature suggests that the pathophysiology of schizophrenia is related to deficits of bioenergetic function. While antipsychotics are an effective therapy for the management of positive psychotic symptoms, they are not efficacious for the complete schizophrenia symptom profile, such as the negative and cognitive symptoms. In this review, we discuss the relationship between dysfunction of various metabolic pathways across different brain regions in relation to schizophrenia. We contend that several bioenergetic subprocesses are affected across the brain and such deficits are a core feature of the illness. We provide an overview of central perturbations of insulin signaling, glycolysis, pentose-phosphate pathway, tricarboxylic acid cycle, and oxidative phosphorylation in schizophrenia. Importantly, we discuss pharmacologic and nonpharmacologic interventions that target these pathways and how such interventions may be exploited to improve the symptoms of schizophrenia.

Dopamine signaling impairs ROS modulation by mitochondrial hexokinase in human neural progenitor cells

Dopamine signaling has numerous roles during brain development. In addition, alterations in dopamine signaling may be also involved in the pathophysiology of psychiatric disorders. Neurodevelopment is modulated in multiple steps by reactive oxygen species (ROS), byproducts of oxidative metabolism that are signaling factors involved in proliferation, differentiation, and migration. Hexokinase (HK), when associated with the mitochondria (mt-HK), is a potent modulator of the generation of mitochondrial ROS in the brain. In the present study, we investigated whether dopamine could affect both the activity and redox function of mt-HK in human neural progenitor cells (NPCs). We found that dopamine signaling via D₁R decreases mt-HK activity and impairs ROS modulation, which is followed by an expressive release of H₂O₂ and impairment in calcium handling by the mitochondria. Nevertheless, mitochondrial respiration is not affected, suggesting specificity for dopamine on mt-HK function. In neural stem cells (NSCs) derived from induced-pluripotent stem cells (iPSCs) of schizophrenia patients, mt-HK is unable to decrease mitochondrial ROS, in contrast with NSCs derived from healthy individuals. Our data point to mitochondrial hexokinase as a novel target of dopaminergic signaling, as well as a redox modulator in human neural progenitor cells, which may be relevant to the pathophysiology of neurodevelopmental disorders such as schizophrenia.

Transcriptional profile of pyramidal neurons in chronic schizophrenia reveals lamina-specific dysfunction of neuronal immunity

While the pathophysiology of schizophrenia has been extensively investigated using homogenized postmortem brain samples, few studies have examined changes in brain samples with techniques that may attribute perturbations to specific cell types. To fill this gap, we performed microarray assays on mRNA isolated from anterior cingulate cortex (ACC) superficial and deep pyramidal neurons from 12 schizophrenia and 12 control subjects using laser-capture microdissection. Among all the annotated genes, we identified 134 significantly increased and 130 decreased genes in superficial pyramidal neurons, while 93 significantly increased and 101 decreased genes were found in deep pyramidal neurons, in schizophrenia compared to control subjects. In these differentially expressed genes, we detected lamina-specific changes of 55 and 31 genes in superficial and deep neurons in schizophrenia, respectively. Gene set enrichment analysis (GSEA) was applied to the entire pre-ranked differential expression gene lists to gain a complete pathway analysis throughout all annotated genes. Our analysis revealed overrepresented groups of gene sets in schizophrenia, particularly in immunity and synapse-related pathways, suggesting the disruption of these pathways plays an important role in schizophrenia. We also detected other pathways previously demonstrated in schizophrenia pathophysiology, including cytokine and chemotaxis, postsynaptic signaling, and glutamatergic synapses. In addition, we observed several novel pathways, including ubiquitin-independent protein catabolic process. Considering the effects of antipsychotic treatment on gene expression, we applied a novel bioinformatics approach to compare our differential expression gene profiles with 51 antipsychotic treatment datasets, demonstrating that our results were not influenced by antipsychotic treatment. Taken together, we found pyramidal neuron-specific changes in neuronal immunity, synaptic dysfunction, and olfactory dysregulation in schizophrenia, providing new insights for the cell-subtype specific pathophysiology of chronic schizophrenia.

Electroacupuncture suppresses glucose metabolism and GLUT-3 expression in medial prefrontal cortical in rats with neuropathic pain

Background

Accumulating evidence has demonstrated that the electroacupuncture (EA) stimulation could effectively alleviate neuropathic pain. The medial prefrontal cortex (mPFC) is a vital part of the cortical representation of pain in the brain, and its glucose metabolism is mostly affected in the progression of pain. However, the central mechanism of EA analgesia remains unclear.

Methods

Fifty-four male SD rats were equally randomized into sham surgery (Sham) group, chronic constriction injury (CCI) group and EA stimulation (EA) group. The CCI model, involving ligature of the right sciatic nerve, was established in all animals except the Sham group. EA stimulation was applied on the right side acupoints of Huantiao (GB30) and Yanglingquan (GB34) in the EA group. Paw withdrawal threshold (PWT) and paw thermal withdrawal latency (PWL) were measured. The ¹⁸ F-fluorodeoxyglucose positron emission tomography (FDG-PET) was used to evaluate glucose metabolism changes in the mPFC. The expression of glucose transporter 3 (GLUT-3) in the mPFC was determined by immune histochemistry and ELISA.

Results

Comparing with CCI groups, EA treatment was obviously reversed CCI-induced mechanical allodynia (P < 0.01), thermal hyperalgesia (P < 0.01) and the increase of glucose metabolism in the left mPFC (P < 0.05). Furthermore, EA treatment significantly decreased the protein expression of GLUT-3 in the left mPFC (P < 0.01).

Conclusions

Our results indicate that EA analgesia effect may be related to suppressing the glucose metabolism and GLUT-3 expression in the mPFC. This study could provide a potential insight into the central mechanisms involved in the analgesic effect of EA.

Cardiac sensory afferents modulate susceptibility to anxio-depressive behaviour in a mouse model of chronic heart failure

AIM

Impairments in cerebral structure and cognitive performance in chronic heart failure (CHF) are critical components of its comorbidity spectrum. Autonomic afferents that arise from cardiac sensory fibres show enhanced activity with CHF. Desensitization of these fibres by local application of resiniferatoxin (RTX) during myocardial infarction (MI) is known to prevent cardiac hypertrophy, sympathetic hyperactivity and CHF. Whether these afferents mediate cerebral allostasis is unknown.

METHODS

CHF was induced by myocardial infarction. To evaluate if cardiac afferents contribute to cerebral allostasis, RTX was acutely applied to the pericardial space in controls (RTX) and in MI treated animals (MI/RTX). Subjects were then evaluated in a series of behavioural tests recapitulating different symptoms of depressive disorders. Proteomics of the frontal cortices (FC) was performed to identify contributing proteins and pathways responsible for behavioural allostasis.

RESULTS

Desensitization of cardiac afferents relieves hallmarks of an anxio/depressive-like state in mice. Unique protein signatures and regulatory pathways in FCs isolated from each treatment reveal the degree of complexity inherent in the FC response to stresses originating in the heart. While cortices from the combined treatment (MI/RTX) did not retain protein signatures from the individual treatment groups, all three groups suffer dysregulation in circadian entrainment.

CONCLUSION

CHF is comorbid with an anxio/depressive-like state and ablation of cardiac afferents relieves the despair phenotype. The strikingly different proteomic profiles observed in FCs suggest that MI and RTX lead to unique brain-signalling patterns and that the combined treatment, potentially through destructive interference mechanisms, most closely resembles controls.

Signature-based approaches for informed drug repurposing: targeting CNS disorders

CNS disorders, and in particular psychiatric illnesses, lack definitive disease-altering therapeutics. The limited understanding of the mechanisms driving these illnesses with the slow pace and high cost of drug development exacerbates this issue. For these reasons, drug repurposing - both a less expensive and time-efficient practice compared to de novo drug development - has been a promising strategy to overcome the paucity of treatments available for these debilitating disorders. While empirical drug-repurposing has been a routine practice in clinical psychiatry, innovative, informed, and cost-effective repurposing efforts using big data ("omics") have been designed to characterize drugs by structural and transcriptomic signatures. These strategies, in conjunction with ontological integration, provide an important opportunity to address knowledge-based challenges associated with drug development for CNS disorders. In this review, we discuss various signature-based in silico approaches to drug repurposing, its integration with multiple omics platforms, and how this data can be used for clinically relevant, evidence-based drug repurposing. These tools provide an exciting translational avenue to merge omics-based drug discovery platforms with patient-specific disease signatures, ultimately facilitating the identification of new therapies for numerous psychiatric disorders.

Exploring cellular markers of metabolic syndrome in peripheral blood mononuclear cells across the neuropsychiatric spectrum

Recent evidence suggests that comorbidities between neuropsychiatric conditions and metabolic syndrome may precede and even exacerbate long-term side-effects of psychiatric medication, such as a higher risk of type 2 diabetes and cardiovascular disease, which result in increased mortality. In the present study we compare the expression of key metabolic proteins, including the insulin receptor (CD220), glucose transporter 1 (GLUT1) and fatty acid translocase (CD36), on peripheral blood mononuclear cell subtypes from patients across the neuropsychiatric spectrum, including schizophrenia, bipolar disorder, major depression and autism spectrum conditions (n = 25/condition), relative to typical controls (n = 100). This revealed alterations in the expression of these proteins that were specific to schizophrenia. Further characterization of metabolic alterations in an extended cohort of first-onset antipsychotic drug-naïve schizophrenia patients (n = 58) and controls (n = 63) revealed that the relationship between insulin receptor expression in monocytes and physiological insulin sensitivity was disrupted in schizophrenia and that altered expression of the insulin receptor was associated with whole genome polygenic risk scores for schizophrenia. Finally, longitudinal follow-up of the schizophrenia patients over the course of antipsychotic drug treatment revealed that peripheral metabolic markers predicted changes in psychopathology and the principal side effect of weight gain at clinically relevant time points. These findings suggest that peripheral blood cells can provide an accessible surrogate model for metabolic alterations in schizophrenia and have the potential to stratify subgroups of patients with different clinical outcomes or a greater risk of developing metabolic complications following antipsychotic therapy.

Abnormal Brain Bioenergetics in First-Episode Psychosis

BACKGROUND

Converging evidence indicates impaired brain energy metabolism in schizophrenia and other psychotic disorders. Creatine kinase (CK) is pivotal in providing adenosine triphosphate in the cell and maintaining its levels when energy demand is increased. However, the activity of CK has not been investigated in patients with first-episode schizophrenia spectrum disorders.

METHODS

Using in vivo phosphorus magnetization transfer spectroscopy, we measured CK first-order forward rate constant (k f ) in the frontal lobe, in patients with first-episode psychosis (FEP; n = 16) and healthy controls (n = 34), at rest.

RESULTS

CK k f was significantly reduced in FEP compared to healthy controls. There were no differences in other energy metabolism-related measures, including phosphocreatine (PCr) or ATP, between groups. We also found increase in glycerol-3-phosphorylcholine, a putative membrane breakdown product, in patients.

CONCLUSIONS

The results of this study indicate that brain bioenergetic abnormalities are already present early in the course of schizophrenia spectrum disorders. Future research is needed to identify the relationship of reduced CK k f with psychotic symptoms and to test treatment alternatives targeting this pathway. Increased glycerol-3-phosphorylcholine is consistent with earlier studies in medication-naïve patients and later studies in first-episode schizophrenia, and suggest enhanced synaptic pruning.

The Relationship between the Level of Anterior Cingulate Cortex Metabolites, Brain-Periphery Redox Imbalance, and the Clinical State of Patients with Schizophrenia and Personality Disorders

Schizophrenia is a complex mental disorder whose course varies with periods of deterioration and symptomatic improvement without diagnosis and treatment specific for the disease. So far, it has not been possible to clearly define what kinds of functional and structural changes are responsible for the onset or recurrence of acute psychotic decompensation in the course of schizophrenia, and to what extent personality disorders may precede the appearance of the appropriate symptoms. The work combines magnetic resonance spectroscopy imaging with clinical evaluation and laboratory tests to determine the likely pathway of schizophrenia development by identifying peripheral cerebral biomarkers compared to personality disorders. The relationship between the level of metabolites in the brain, the clinical status of patients according to International Statistical Classification of Diseases and Related Health Problems, 10th Revision ICD-10, duration of untreated psychosis (DUP), and biochemical indices related to redox balance (malondialdehyde), the efficiency of antioxidant systems (FRAP), and bioenergetic metabolism of mitochondria, were investigated. There was a reduction in the level of brain N-acetyl-aspartate and glutamate in the anterior cingulate gyrus of patients with schisophrenia compared to the other groups that seems more to reflect a biological etiopathological factor of psychosis. Decreased activity of brain metabolites correlated with increased peripheral oxidative stress (increased malondialdehyde MDA) associated with decreased efficiency of antioxidant systems (FRAP) and the breakdown of clinical symptoms in patients with schizophrenia in the course of psychotic decompensation compared to other groups. The period of untreated psychosis correlated negatively with glucose value in the brain of people with schizophrenia, and positively with choline level. The demonstrated differences between two psychiatric units, such as schizophrenia and personality disorders in relation to healthy people, may be used to improve the diagnosis and prognosis of schizophrenia compared to other heterogenous psychopathology in the future. The collapse of clinical symptoms of patients with schizophrenia in the course of psychotic decompensation may be associated with the occurrence of specific schizotypes, the determination of which is possible by determining common relationships between changes in metabolic activity of particular brain structures and peripheral parameters, which may be an important biological etiopathological factor of psychosis. Markers of peripheral redox imbalance associated with disturbed bioenergy metabolism in the brain may provide specific biological factors of psychosis however, they need to be confirmed in further studies.

Evidence for altered energy metabolism, increased lactate, and decreased pH in schizophrenia brain: A focused review and meta-analysis of human postmortem and magnetic resonance spectroscopy studies

Though the pathophysiology of schizophrenia remains poorly understood, altered brain energy metabolism is increasingly implicated. Here, we conduct meta-analyses of the available human studies measuring lactate or pH in schizophrenia brain and discuss the accumulating evidence for increased lactate and decreased pH in schizophrenia brain and evidence linking these to negative and cognitive symptom severity. Meta-analysis of six postmortem studies revealed a significant increase in lactate in schizophrenia brain while meta-analysis of 14 magnetic resonance spectroscopy studies did not reveal a significant change in brain pH in schizophrenia. However, only five of these studies were likely sufficiently powered to detect differences in brain pH, and meta-analysis of these five studies found a nonsignificant decrease in pH in schizophrenia brain. Next, we discuss evidence for altered brain energy metabolism in schizophrenia and how this may underlie a buildup of lactate and decreased pH. This alteration, similar to the Warburg effect extensively described in cancer biology, involves diminished tricarboxylic acid cycle and oxidative phosphorylation along with a shift toward increased reliance on glycolysis for energy production. We then explore the role that mitochondrial dysfunction, oxidative stress, and hypoxia-related changes in gene expression likely play in this shift in brain energy metabolism and address the functional consequences of lowered brain pH in schizophrenia including alterations in neurotransmitter regulation, mRNA stability, and overall patterns of gene expression. Finally, we discuss how altered energy metabolism in schizophrenia brain may serve as an effective target in the treatment of this illness.

Mitochondrial Dysfunction in Schizophrenia

Schizophrenia (SCZ) is a severe neurodevelopmental disorder affecting 1% of populations worldwide with a grave disability and socioeconomic burden. Current antipsychotic medications are effective treatments for positive symptoms, but poorly address negative symptoms and cognitive symptoms, warranting the development of better treatment options. Further understanding of SCZ pathogenesis is critical in these endeavors. Accumulating evidence has pointed to the role of mitochondria and metabolic dysregulation in SCZ pathogenesis. This review critically summarizes recent studies associating a compromised mitochondrial function with people with SCZ, including postmortem studies, imaging studies, genetic studies, and induced pluripotent stem cell studies. This review also discusses animal models with mitochondrial dysfunction resulting in SCZ-relevant neurobehavioral abnormalities, as well as restoration of mitochondrial function as potential therapeutic targets. Further understanding of mitochondrial dysfunction in SCZ may open the door to develop novel therapeutic strategies that can address the symptoms that cannot be adequately addressed by current antipsychotics alone.

Oxidative-Antioxidant Imbalance and Impaired Glucose Metabolism in Schizophrenia

Schizophrenia is a neurodevelopmental disorder featuring chronic, complex neuropsychiatric features. The etiology and pathogenesis of schizophrenia are not fully understood. Oxidative-antioxidant imbalance is a potential determinant of schizophrenia. Oxidative, nitrosative, or sulfuric damage to enzymes of glycolysis and tricarboxylic acid cycle, as well as calcium transport and ATP biosynthesis might cause impaired bioenergetics function in the brain. This could explain the initial symptoms, such as the first psychotic episode and mild cognitive impairment. Another concept of the etiopathogenesis of schizophrenia is associated with impaired glucose metabolism and insulin resistance with the activation of the mTOR mitochondrial pathway, which may contribute to impaired neuronal development. Consequently, cognitive processes requiring ATP are compromised and dysfunctions in synaptic transmission lead to neuronal death, preceding changes in key brain areas. This review summarizes the role and mutual interactions of oxidative damage and impaired glucose metabolism as key factors affecting metabolic complications in schizophrenia. These observations may be a premise for novel potential therapeutic targets that will delay not only the onset of first symptoms but also the progression of schizophrenia and its complications.

Protein expression of prenyltransferase subunits in postmortem schizophrenia dorsolateral prefrontal cortex

The pathophysiology of schizophrenia includes altered neurotransmission, dysregulated intracellular signaling pathway activity, and abnormal dendritic morphology that contribute to deficits of synaptic plasticity in the disorder. These processes all require dynamic protein-protein interactions at cell membranes. Lipid modifications target proteins to membranes by increasing substrate hydrophobicity by the addition of a fatty acid or isoprenyl moiety, and recent evidence suggests that dysregulated posttranslational lipid modifications may play a role in multiple neuropsychiatric disorders, including schizophrenia. Consistent with these emerging findings, we have recently reported decreased protein S-palmitoylation in schizophrenia. Protein prenylation is a lipid modification that occurs upstream of S-palmitoylation on many protein substrates, facilitating membrane localization and activity of key intracellular signaling proteins. Accordingly, we hypothesized that, in addition to palmitoylation, protein prenylation may be abnormal in schizophrenia. To test this, we assayed protein expression of the five prenyltransferase subunits (FNTA, FNTB, PGGT1B, RABGGTA, and RABGGTB) in postmortem dorsolateral prefrontal cortex from patients with schizophrenia and paired comparison subjects (n = 13 pairs). We found decreased levels of FNTA (14%), PGGT1B (13%), and RABGGTB (8%) in schizophrenia. To determine whether upstream or downstream factors may be driving these changes, we also assayed protein expression of the isoprenoid synthases FDPS and GGPS1 and prenylation-dependent processing enzymes RCE and ICMT. We found these upstream and downstream enzymes to have normal protein expression. To rule out effects from chronic antipsychotic treatment, we assayed FNTA, PGGT1B, and RABGGTB in the cortex from rats treated long-term with haloperidol decanoate and found no change in the expression of these proteins. Given the role prenylation plays in localization of key signaling proteins found at the synapse, these data offer a potential mechanism underlying abnormal protein-protein interactions and protein localization in schizophrenia.

Lactate measurement by neurochemical profiling in the dorsolateral prefrontal cortex at 7T: accuracy, precision, and relaxation times

PURPOSE

This assesses the potential of measuring lactate in the human brain using three non-editing MRS methods at 7T and compares the accuracy and precision of the methods.

METHODS

¹ H MRS data were measured in the right dorsolateral prefrontal cortex using a semi-adiabatic spin-echo full-intensity acquired localized sequence with three different protocols: (I) TE = 16 ms, (II) TE = 110 ms, and (III) TE = 16 ms, TI = 300 ms. T₁ and T₂ relaxation times of lactate were also measured. Simulated spectra were generated for three protocols with known concentrations, using a range of spectral linewidths and SNRs to assess the effect of data quality on the measurement precision and accuracy.

RESULTS

Lactate was quantified in all three protocols with mean Cramér-Rao lower bound of 8% (I), 13% (II), and 7% (III). The T₁ and T₂ relaxation times of lactate were 1.9 ± 0.2 s and 94 ± 13 ms, respectively. Simulations predicted a spectral linewidth-associated underestimation of lactate measurement. Simulations, phantom and in vivo results showed that protocol II was most affected by this underestimation. In addition, the estimation error was insensitive to a broad range of spectral linewidth with protocol I. Within-session coefficient of variances of lactate were 6.1 ± 7.9% (I), 22.3 ± 12.3% (II), and 5.1 ± 5.4% (III), respectively.

CONCLUSION

We conclude that protocols I and III have the potential to measure lactate at 7T with good reproducibility, whereas the measurement accuracy and precision depend on spectral linewidth and SNR, respectively. Moreover, simulation is valuable for the optimization of measurement protocols in future study design and the correction for measurement bias.

Excess hydrogen sulfide and polysulfides production underlies a schizophrenia pathophysiology

Mice with the C3H background show greater behavioral propensity for schizophrenia, including lower prepulse inhibition (PPI), than C57BL/6 (B6) mice. To characterize as-yet-unknown pathophysiologies of schizophrenia, we undertook proteomics analysis of the brain in these strains, and detected elevated levels of Mpst, a hydrogen sulfide (H₂ S)/polysulfide-producing enzyme, and greater sulfide deposition in C3H than B6 mice. Mpst-deficient mice exhibited improved PPI with reduced storage sulfide levels, while Mpst-transgenic (Tg) mice showed deteriorated PPI, suggesting that "sulfide stress" may be linked to PPI impairment. Analysis of human samples demonstrated that the H₂ S/polysulfides production system is upregulated in schizophrenia. Mechanistically, the Mpst-Tg brain revealed dampened energy metabolism, while maternal immune activation model mice showed upregulation of genes for H₂ S/polysulfides production along with typical antioxidative genes, partly via epigenetic modifications. These results suggest that inflammatory/oxidative insults in early brain development result in upregulated H₂ S/polysulfides production as an antioxidative response, which in turn cause deficits in bioenergetic processes. Collectively, this study presents a novel aspect of the neurodevelopmental theory for schizophrenia, unraveling a role of excess H₂ S/polysulfides production.

Transcript Analysis of Zebrafish GLUT3 Genes, slc2a3a and slc2a3b, Define Overlapping as Well as Distinct Expression Domains in the Zebrafish (Danio rerio) Central Nervous System

The transport of glucose across the cell plasma membrane is vital to most mammalian cells. The glucose transporter (GLUT; also called SLC2A) family of transmembrane solute carriers is responsible for this function in vivo. GLUT proteins encompass 14 different isoforms in humans with different cell type-specific expression patterns and activities. Central to glucose utilization and delivery in the brain is the neuronally expressed GLUT3. Recent research has shown an involvement of GLUT3 genetic variation or altered expression in several different brain disorders, including Huntington's and Alzheimer's diseases. Furthermore, GLUT3 was identified as a potential risk gene for multiple psychiatric disorders. To study the role of GLUT3 in brain function and disease a more detailed knowledge of its expression in model organisms is needed. Zebrafish (Danio rerio) has in recent years gained popularity as a model organism for brain research and is now well-established for modeling psychiatric disorders. Here, we have analyzed the sequence of GLUT3 orthologs and identified two paralogous genes in the zebrafish, slc2a3a and slc2a3b. Interestingly, the Glut3b protein sequence contains a unique stretch of amino acids, which may be important for functional regulation. The slc2a3a transcript is detectable in the central nervous system including distinct cellular populations in telencephalon, diencephalon, mesencephalon and rhombencephalon at embryonic and larval stages. Conversely, the slc2a3b transcript shows a rather diffuse expression pattern at different embryonic stages and brain regions. Expression of slc2a3a is maintained in the adult brain and is found in the telencephalon, diencephalon, mesencephalon, cerebellum and medulla oblongata. The slc2a3b transcripts are present in overlapping as well as distinct regions compared to slc2a3a. Double in situ hybridizations were used to demonstrate that slc2a3a is expressed by some GABAergic neurons at embryonic stages. This detailed description of zebrafish slc2a3a and slc2a3b expression at developmental and adult stages paves the way for further investigations of normal GLUT3 function and its role in brain disorders.

Connectivity Analyses of Bioenergetic Changes in Schizophrenia: Identification of Novel Treatments

We utilized a cell-level approach to examine glycolytic pathways in the DLPFC of subjects with schizophrenia (n = 16) and control (n = 16) and found decreased mRNA expression of glycolytic enzymes in pyramidal neurons, but not astrocytes. To replicate these novel bioenergetic findings, we probed independent datasets for bioenergetic targets and found similar abnormalities. Next, we used a novel strategy to build a schizophrenia bioenergetic profile by a tailored application of the Library of Integrated Network-Based Cellular Signatures data portal (iLINCS) and investigated connected cellular pathways, kinases, and transcription factors using Enrichr. Finally, with the goal of identifying drugs capable of "reversing" the bioenergetic schizophrenia signature, we performed a connectivity analysis with iLINCS and identified peroxisome proliferator-activated receptor (PPAR) agonists as promising therapeutic targets. We administered a PPAR agonist to the GluN1 knockdown model of schizophrenia and found it improved long-term memory. Taken together, our findings suggest that tailored bioinformatics approaches, coupled with the LINCS library of transcriptional signatures of chemical and genetic perturbagens, may be employed to identify novel treatment strategies for schizophrenia and related diseases.

Ketogenic diet prevents impaired prepulse inhibition of startle in an acute NMDA receptor hypofunction model of schizophrenia

Recent transcriptomic, proteomic and metabolomics studies have highlighted an abnormal cerebral glucose and energy metabolism as one of the potential pathophysiological mechanisms of schizophrenia. This raises the possibility that a metabolically-based intervention might have therapeutic value in the management of schizophrenia, a notion supported by our recent results that a low carbohydrate/high-fat therapeutic ketogenic diet (KD) prevented a variety of behavioural abnormalities induced by pharmacological inhibition of NMDA glutamate receptors. Here we asked if the beneficial effects of KD can be generalised to impaired prepulse inhibition of startle (PPI), a translationally validated endophenotype of schizophrenia, in a pharmacological model in mice. Furthermore, we addressed the issue of whether the effect of KD is linked to the calorie-restricted state typical of the initial phase of KD. We fed male C57BL/6 mice a KD for 7 weeks and tested PPI at 3 and 7 weeks, in the presence and absence of a significant digestible energy deficit, respectively. We used an NMDA receptor hypo-function model of schizophrenia induced by acute injection of dizocilpine (MK-801). We found that KD effectively prevented MK-801-induced PPI impairments at both 3 and 7 weeks, irrespective of the presence or absence of digestible energy deficit. Furthermore, there was a lack of correlation between PPI and body weight changes. These results support the efficacy of the therapeutic KD in a translational model of schizophrenia and furthermore provide evidence against the role of calorie restriction in its mechanism of action.

Measurement of lactate levels in postmortem brain, iPSCs, and animal models of schizophrenia

Converging evidence suggests bioenergetic defects contribute to the pathophysiology of schizophrenia and may underlie cognitive dysfunction. The transport and metabolism of lactate energetically couples astrocytes and neurons and supports brain bioenergetics. We examined the concentration of lactate in postmortem brain (dorsolateral prefrontal cortex) in subjects with schizophrenia, in two animal models of schizophrenia, the GluN1 knockdown mouse model and mutant disrupted in schizophrenia 1 (DISC1) mouse model, as well as inducible pluripotent stem cells (iPSCs) from a schizophrenia subject with the DISC1 mutation. We found increased lactate in the dorsolateral prefrontal cortex (p = 0.043, n = 16/group) in schizophrenia, as well as in frontal cortical neurons differentiated from a subject with schizophrenia with the DISC1 mutation (p = 0.032). We also found a decrease in lactate in mice with induced expression of mutant human DISC1 specifically in astrocytes (p = 0.049). These results build upon the body of evidence supporting bioenergetic dysfunction in schizophrenia, and suggests changes in lactate are a key feature of this often devastating severe mental illness.

The Therapeutic Potential of Ketogenic Diet Throughout Life: Focus on Metabolic, Neurodevelopmental and Neurodegenerative Disorders

This chapter reviews the efficacy of the ketogenic diet in a variety of neurodegenerative, neurodevelopmental and metabolic conditions throughout different stages of life. It describes conditions affecting children, metabolic disorders in adults and disorderrs affecting the elderly. We have focused on application of the ketogenic diet in clinical studies and in preclinical models and discuss the benefits and negative aspects of the diet. Finally, we highlight the need for further research in this area with a view of discovering novel mechanistic targets of the ketogenic diet, as a means of maximising the potential benefits/risks ratio.

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.