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

Incomplete autophagy and increased cholesterol synthesis during neuronal cell death caused by a synthetic cannabinoid, CP-55,940

There is a propensity for synthetic cannabinoid abuse to spread worldwide. CP-55,940, a synthetic cannabinoid having the ability to activate both CB1 and CB2 receptors, has been shown to induce cell death in neurons as well as other cells. Here we investigate molecular events underling the adverse effects of CP-55,940 on neuronal cells. Exposure of mouse neuroblastoma Neuro2a cells to 10-50 µM CP-55,940 results in concentration-dependent cell death that is not accompanied by an induction of apoptosis. CP-55,940 also stimulates autophagy, but the stimulation is not followed by an increase in autophagic degradation. Transcriptome analysis using DNA microarray revealed the increased expression of genes for the cholesterol biosynthesis pathway that is associated with the activation of SREBP-2, the master transcriptional regulator of cholesterol biosynthesis. However, free cholesterol is localized mainly to cytoplasmic structures, although it is localized to the plasma membrane in healthy cells. Thus, cellular trafficking of cholesterol seems to be somewhat disrupted in CP-55,940 stimulated cells. These results show for the first time that CP-55,940 stimulates autophagy as well as cholesterol biosynthesis, although not all the processes involved in the cellular response to CP-55,940 seem to be complete in these cells.

Olanzapine, risperidone and ziprasidone differently affect lysosomal function and autophagy, reflecting their different metabolic risk in patients

The metabolic effects induced by antipsychotics in vitro depend on their action on the trafficking and biosynthesis of sterols and lipids. Previous research showed that antipsychotics with different adverse effects in patients cause similar alterations in vitro, suggesting the low clinical usefulness of cellular studies. Moreover, the inhibition of peripheral AMPK was suggested as potential aetiopathogenic mechanisms of olanzapine, and different effects on autophagy were reported for several antipsychotics. We thus assessed, in clinically-relevant culture conditions, the aetiopathogenic mechanisms of olanzapine, risperidone and ziprasidone, antipsychotics with respectively high, medium, low metabolic risk in patients, finding relevant differences among them. We highlighted that: olanzapine impairs lysosomal function affecting autophagy and autophagosome clearance, and increasing intracellular lipids and sterols; ziprasidone activates AMPK increasing the autophagic flux and reducing intracellular lipids; risperidone increases lipid accumulation, while it does not affect lysosomal function. These in vitro differences align with their different impact on patients. We also provided evidence that metformin add-on improved autophagy in olanzapine-treated cells and reduced lipid accumulation induced by both risperidone and olanzapine in an AMPK-dependent way; metformin also increased the production of bile acids to eliminate cholesterol accumulations caused by olanzapine. These results have different clinical implications. We demonstrated that antipsychotics with different metabolic impacts on patients actually have different mechanisms of action, thus supporting the possibility of a personalised antipsychotic treatment. Moreover, we found that metformin can fully revert the phenotype caused by risperidone but not the one caused by olanzapine, that still activates SREBP2.

Methotrimeprazine is a neuroprotective antiviral in JEV infection via adaptive ER stress and autophagy

Japanese encephalitis virus (JEV) pathogenesis is driven by a combination of neuronal death and neuroinflammation. We tested 42 FDA-approved drugs that were shown to induce autophagy for antiviral effects. Four drugs were tested in the JE mouse model based on in vitro protective effects on neuronal cell death, inhibition of viral replication, and anti-inflammatory effects. The antipsychotic phenothiazines Methotrimeprazine (MTP) & Trifluoperazine showed a significant survival benefit with reduced virus titers in the brain, prevention of BBB breach, and inhibition of neuroinflammation. Both drugs were potent mTOR-independent autophagy flux inducers. MTP inhibited SERCA channel functioning, and induced an adaptive ER stress response in diverse cell types. Pharmacological rescue of ER stress blocked autophagy and antiviral effect. MTP did not alter translation of viral RNA, but exerted autophagy-dependent antiviral effect by inhibiting JEV replication complexes. Drug-induced autophagy resulted in reduced NLRP3 protein levels, and attenuation of inflammatory cytokine/chemokine release from infected microglial cells. Our study suggests that MTP exerts a combined antiviral and anti-inflammatory effect in JEV infection, and has therapeutic potential for JE treatment.

Haloperidol alters neurotrophic factors and epigenetic parameters in an animal model of schizophrenia induced by ketamine

This study aimed to evaluate Haloperidol's (Hal) effects on the behavioral, neurotrophic factors, and epigenetic parameters in an animal model of schizophrenia (SCZ) induced by ketamine (Ket). Injections of Ket or saline were administered intraperitoneal (once a day) between the 1st and 14th days of the experiment. Water or Hal was administered via gavage between the 8th and 14th experimental days. Thirty minutes after the last injection, the animals were subjected to behavioral analysis. The activity of DNA methyltransferase (DNMT), histone deacetylase (HDAC), and histone acetyltransferase and levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3), and glial-derived neurotrophic factor (GDNF) were evaluated in the frontal cortex, hippocampus, and striatum. Ket increased the covered distance and time spent in the central area of the open field, and Hal did not reverse these behavioral alterations. Significant increases in the DNMT and HDAC activities were detected in the frontal cortex and striatum from rats that received Ket, Hal, or a combination thereof. Besides, Hal per se increased the activity of DNMT and HDAC in the hippocampus of rats. Hal per se or the association of Ket plus Hal decreased BDNF, NGF, NT-3, and GDNF, depending on the brain region and treatment regimen. The administration of Hal can alter the levels of neurotrophic factors and the activity of epigenetic enzymes, which can be a factor in the development of effect collateral in SCZ patients. However, the precise mechanisms involved in these alterations are still unclear.

DPYSL2/CRMP2 isoform B knockout in human iPSC-derived glutamatergic neurons confirms its role in mTOR signaling and neurodevelopmental disorders

The DPYSL2/CRMP2 gene encodes a microtubule-stabilizing protein crucial for neurogenesis and is associated with numerous psychiatric and neurodegenerative disorders including schizophrenia, bipolar disorder, and Alzheimer's disease. DPYSL2 generates multiple RNA and protein isoforms, but few studies have differentiated between them. We previously reported an association of a functional variant in the DPYSL2-B isoform with schizophrenia (SCZ) and demonstrated in HEK293 cells that this variant reduced the length of cellular projections and created transcriptomic changes that captured schizophrenia etiology by disrupting mTOR signaling-mediated regulation. In the present study, we follow up on these results by creating, to our knowledge, the first models of endogenous DPYSL2-B knockout in human induced pluripotent stem cells (iPSCs) and neurons. CRISPR/Cas9-faciliated knockout of DPYSL2-B in iPSCs followed by Ngn2-induced differentiation to glutamatergic neurons showed a reduction in DPYSL2-B/CRMP2-B RNA and protein with no observable impact on DPYSL2-A/CRMP2-A. The average length of dendrites in knockout neurons was reduced up to 58% compared to controls. Transcriptome analysis revealed disruptions in pathways highly relevant to psychiatric disease including mTOR signaling, cytoskeletal dynamics, immune function, calcium signaling, and cholesterol biosynthesis. We also observed a significant enrichment of the differentially expressed genes in SCZ-associated loci from genome-wide association studies (GWAS). Our findings expand our previous results to neuronal cells, clarify the functions of the human DPYSL2-B isoform and confirm its involvement in molecular pathologies shared between many psychiatric diseases.

Phosphoproteomic Analysis of Dopamine D2 Receptor Signaling Reveals Interplay of G Protein- and β-Arrestin-Mediated Effects

Leveraging biased signaling of G protein-coupled receptors has been proposed as a promising strategy for the development of drugs with higher specificity. However, the consequences of selectively targeting G protein- or β-arrestin-mediated signaling on cellular functions are not comprehensively understood. In this study, we utilized phosphoproteomics to gain a systematic overview of signaling induced by the four biased and balanced dopamine D2 receptor (D₂R) ligands MS308, BM138, quinpirole, and sulpiride in an in vitro D₂R transfection model. Quantification of 14,160 phosphosites revealed a low impact of the partial G protein agonist MS308 on cellular protein phosphorylation, as well as surprising similarities between the balanced agonist quinpirole and the inverse agonist sulpiride. Analysis of the temporal profiles of ligand-induced phosphorylation events showed a transient impact of the G protein-selective agonist MS308, whereas the β-arrestin-preferring agonist BM138 elicited a delayed, but more pronounced response. Functional enrichment analysis of ligand-impacted phosphoproteins and treatment-linked kinases confirmed multiple known functions of D₂R signaling while also revealing novel effects, for example of MS308 on sterol regulatory element-binding protein-related gene expression. All raw data were deposited in MassIVE (MSV000089457).

Clozapine's multiple cellular mechanisms: What do we know after more than fifty years? A systematic review and critical assessment of translational mechanisms relevant for innovative strategies in treatment-resistant schizophrenia

Almost fifty years after its first introduction into clinical care, clozapine remains the only evidence-based pharmacological option for treatment-resistant schizophrenia (TRS), which affects approximately 30% of patients with schizophrenia. Despite the long-time experience with clozapine, the specific mechanism of action (MOA) responsible for its superior efficacy among antipsychotics is still elusive, both at the receptor and intracellular signaling level. This systematic review is aimed at critically assessing the role and specific relevance of clozapine's multimodal actions, dissecting those mechanisms that under a translational perspective could shed light on molecular targets worth to be considered for further innovative antipsychotic development. In vivo and in vitro preclinical findings, supported by innovative techniques and methods, together with pharmacogenomic and in vivo functional studies, point to multiple and possibly overlapping MOAs. To better explore this crucial issue, the specific affinity for 5-HT₂R, D1R, α_2c, and muscarinic receptors, the relatively low occupancy at dopamine D2R, the interaction with receptor dimers, as well as the potential confounder effects resulting in biased ligand action, and lastly, the role of the moiety responsible for lipophilic and alkaline features of clozapine are highlighted. Finally, the role of transcription and protein changes at the synaptic level, and the possibility that clozapine can directly impact synaptic architecture are addressed. Although clozapine's exact MOAs that contribute to its unique efficacy and some of its severe adverse effects have not been fully understood, relevant information can be gleaned from recent mechanistic understandings that may help design much needed additional therapeutic strategies for TRS.

Environmentally relevant concentrations of clozapine induced lipotoxicity and gut microbiota dysbiosis in Chinese rare minnow (Gobiocypris rarus)

Clozapine (CLZ) is a neuroactive pharmaceutical that is frequently detected in aquatic environments. Although the cardiotoxicity, developmental toxicity, and neurotoxicity of CLZ in aquatic non-target organisms have been reported, its lipotoxicity and underlying mechanism are unknown. Therefore, in this study, 2-month-old Chinese rare minnows were exposed to 0, 0.1, 1, and 10 μg/L CLZ for 90 days. Overt dyslipidemia was observed after CLZ exposure, whereas the body weights of females significantly increased after CLZ exposure (p < 0.05). In addition, obvious hepatocyte vacuolization and hepatic lipid droplet accumulation were observed at all treatment groups (p < 0.05). The activities of sterol regulatory element binding proteins 1 (SREBP1) and fatty acid synthase (FAS) were significantly upregulated at the 1 and 10 μg/L CLZ treatment groups (p < 0.05). Moreover, evident cell boundary disintegration of the intestinal villi and increasing mucus secretion were observed at all treatment groups (p < 0.05). Furthermore, the diversity of the gut microbiota increased, whereas the relative abundances of Proteobacteria, Firmicutes and Bacteroidetes significantly increased after CLZ exposure (p < 0.05). Furthermore, significantly increased bacterial secondary bile acid biosynthesis activity in Chinese rare minnows was observed after 1 μg/L CLZ exposure (p < 0.05). Therefore, our findings confirmed that CLZ induced lipotoxicity by stimulating SREBP1 and affecting the bacterial secondary bile acid biosynthesis activity in Chinese rare minnows.

Biological Mechanism(s) Underpinning the Association between Antipsychotic Drugs and Weight Gain

Weight gain and consequent metabolic alterations are common side-effects of many antipsychotic drugs. Interestingly, several studies have suggested that improvement in symptoms and adverse metabolic effects are correlated. We used next generation sequencing data from NT-2 (human neuronal) cells treated with aripiprazole, amisulpride, risperidone, quetiapine, clozapine, or vehicle control, and compared with the Pillinger P-score (ranked from 0 to 1, indicating greater increase in weight gain and related metabolic parameters) to identify the genes most associated with the drugs' propensity to cause weight gain. The top 500 genes ranked for their correlation with the drugs' propensity to cause weight gain were subjected to pathway analysis using DAVID (NIH). We further investigated transcription factors (TFs) that are more likely to regulate the genes involved in these processes using the prediction tool of key TFs from TRRUST. The results suggest an enrichment for genes involved in lipid biosynthesis and metabolism, which are of interest for mechanisms underpinning weight-gain. The list of genes involved in the lipid pathways that correlated with weight gain was enriched for genes transcriptionally regulated by SREBF1 and SREBF2. Furthermore, quetiapine significantly increased the expression of SREBF1 and SREBF2 in NT-2 cells. Our results suggest that the effects of these antipsychotic drugs on lipid metabolism may be mediated, at least in part, via regulation of SREBF1/SREBF2 expression, with evidence of a direct effect of quetiapine on the expression of SREBF1/2. The effects of antipsychotic drugs on lipid metabolism may influence white matter structure (therapeutic effect) and the risk of weight gain, lipid disturbances, and, consequently, metabolic syndrome (adverse effects). Understanding the different molecular effects of these drugs could inform a personalized medicine approach in treating patients with schizophrenia.

Selective estrogen receptor modulators (SERMs) affect cholesterol homeostasis through the master regulators SREBP and LXR

Selective estrogen receptor modulators (SERMs) are nonsteroidal drugs that display an estrogen-agonist or estrogen-antagonist effect depending on the tissue targeted. SERMs have attracted great clinical interest for the treatment of several pathologies, most notably breast cancer and osteoporosis. There is strong evidence that SERMs secondarily affect cholesterol metabolism, although the mechanism has not been fully elucidated. In this study, we analysed the effect of the SERMs tamoxifen, raloxifene, and toremifene on the expression of lipid metabolism genes by microarrays and quantitative PCR in different cell types, and ascertained the main mechanisms involved. The three SERMs increased the expression of sterol regulatory element-binding protein (SREBP) target genes, especially those targeted by SREBP-2. In consonance, SERMs increased SREBP-2 processing. These effects were associated to the interference with intracellular LDL-derived cholesterol trafficking. When the cells were exposed to LDL, but not to cholesterol/methyl-cyclodextrin complexes, the SERM-induced increases in gene expression were synergistic with those induced by lovastatin. Furthermore, the SERMs reduced the stimulation of the transcriptional activity of the liver X receptor (LXR) by exogenous cholesterol. However, their impact on the expression of the LXR canonical target ABCA1 in the presence of LDL was cell-type dependent. These actions of SERMs were independent of estrogen receptors. We conclude that, by inhibiting the intracellular trafficking of LDL-derived cholesterol, SERMs promote the activation of SREBP-2 and prevent the activation of LXR, two master regulators of cellular cholesterol metabolism. This study highlights the impact of SERMs on lipid homeostasis regulation beyond their actions as estrogen receptor modulators.

Combined morphological and proteome profiling reveals target-independent impairment of cholesterol homeostasis

Unbiased profiling approaches are powerful tools for small-molecule target or mode-of-action deconvolution as they generate a holistic view of the bioactivity space. This is particularly important for non-protein targets that are difficult to identify with commonly applied target identification methods. Thereby, unbiased profiling can enable identification of novel bioactivity even for annotated compounds. We report the identification of a large bioactivity cluster comprised of numerous well-characterized drugs with different primary targets using a combination of the morphological Cell Painting Assay and proteome profiling. Cluster members alter cholesterol homeostasis and localization due to their physicochemical properties that lead to protonation and accumulation in lysosomes, an increase in lysosomal pH, and a disturbed cholesterol homeostasis. The identified cluster enables identification of modulators of cholesterol homeostasis and links regulation of genes or proteins involved in cholesterol synthesis or trafficking to physicochemical properties rather than to nominal targets.

Antipsychotic drugs counteract autophagy and mitophagy in multiple sclerosis

Multiple sclerosis (MS) is a neuroinflammatory and neurodegenerative disease characterized by myelin damage followed by axonal and ultimately neuronal loss. The etiology and physiopathology of MS are still elusive, and no fully effective therapy is yet available. We investigated the role in MS of autophagy (physiologically, a controlled intracellular pathway regulating the degradation of cellular components) and of mitophagy (a specific form of autophagy that removes dysfunctional mitochondria). We found that the levels of autophagy and mitophagy markers are significantly increased in the biofluids of MS patients during the active phase of the disease, indicating activation of these processes. In keeping with this idea, in vitro and in vivo MS models (induced by proinflammatory cytokines, lysolecithin, and cuprizone) are associated with strongly impaired mitochondrial activity, inducing a lactic acid metabolism and prompting an increase in the autophagic flux and in mitophagy. Multiple structurally and mechanistically unrelated inhibitors of autophagy improved myelin production and normalized axonal myelination, and two such inhibitors, the widely used antipsychotic drugs haloperidol and clozapine, also significantly improved cuprizone-induced motor impairment. These data suggest that autophagy has a causal role in MS; its inhibition strongly attenuates behavioral signs in an experimental model of the disease. Therefore, haloperidol and clozapine may represent additional therapeutic tools against MS.

Cell cycle dependence on the mevalonate pathway: Role of cholesterol and non-sterol isoprenoids

The mevalonate pathway is responsible for the synthesis of isoprenoids, including sterols and other metabolites that are essential for diverse biological functions. Cholesterol, the main sterol in mammals, and non-sterol isoprenoids are in high demand by rapidly dividing cells. As evidence of its importance, many cell signaling pathways converge on the mevalonate pathway and these include those involved in proliferation, tumor-promotion, and tumor-suppression. As well as being a fundamental building block of cell membranes, cholesterol plays a key role in maintaining their lipid organization and biophysical properties, and it is crucial for the function of proteins located in the plasma membrane. Importantly, cholesterol and other mevalonate derivatives are essential for cell cycle progression, and their deficiency blocks different steps in the cycle. Furthermore, the accumulation of non-isoprenoid mevalonate derivatives can cause DNA replication stress. Identification of the mechanisms underlying the effects of cholesterol and other mevalonate derivatives on cell cycle progression may be useful in the search for new inhibitors, or the repurposing of preexisting cholesterol biosynthesis inhibitors to target cancer cell division. In this review, we discuss the dependence of cell division on an active mevalonate pathway and the role of different mevalonate derivatives in cell cycle progression.

Qki regulates myelinogenesis through Srebp2-dependent cholesterol biosynthesis

Myelination depends on timely, precise control of oligodendrocyte differentiation and myelinogenesis. Cholesterol is the most abundant component of myelin and essential for myelin membrane assembly in the central nervous system. However, the underlying mechanisms of precise control of cholesterol biosynthesis in oligodendrocytes remain elusive. In the present study, we found that Qki depletion in neural stem cells or oligodendrocyte precursor cells in neonatal mice resulted in impaired cholesterol biosynthesis and defective myelinogenesis without compromising their differentiation into Aspa⁺Gstpi⁺ myelinating oligodendrocytes. Mechanistically, Qki-5 functions as a co-activator of Srebp2 to control transcription of the genes involved in cholesterol biosynthesis in oligodendrocytes. Consequently, Qki depletion led to substantially reduced concentration of cholesterol in mouse brain, impairing proper myelin assembly. Our study demonstrated that Qki-Srebp2-controlled cholesterol biosynthesis is indispensable for myelinogenesis and highlights a novel function of Qki as a transcriptional co-activator beyond its canonical function as an RNA-binding protein.

New Avenues for Treatment and Prevention of Drug-Induced Steatosis and Steatohepatitis: Much More Than Antioxidants

Drug-induced lipid accumulation in the liver may induce two clinically relevant conditions, drug-induced steatosis (DIS) and drug-induced steatohepatitis (DISH). The list of drugs that may cause DIS or DISH is long and heterogeneous and includes therapeutically relevant molecules that cannot be easily replaced by less hepatotoxic medicines, therefore making specific strategies necessary for DIS/DISH prevention or treatment. For years, the only available tools to achieve these goals have been antioxidant drugs and free radical scavengers, which counteract drug-induced mitochondrial dysfunction but, unfortunately, have only limited efficacy. In the present review we illustrate how in vitro preclinical research unraveled new key players in the pathogenesis of specific forms of DISH, and how, in a few cases, proof of concept of the beneficial effects of their pharmacological modulation has been obtained in vivo in animal models of this condition. The key issue emerging from these studies is that, in selected cases, liver toxicity depends on mechanisms unrelated to those responsible for the desired, primary pharmacological effects of the toxic drug and, therefore, specific strategies can be designed to overcome steatogenicity without making the drug ineffective. In particular, the hepatotoxic drug could be given in combination with a second molecule intended to selectively antagonize its liver toxicity whilst, ideally, potentiating its desired pharmacological activity. Although most of the evidence that we discuss is from in vitro or animal models and will need to be further explored and validated in humans, it highlights new avenues to be pursued in order to improve the safety of steatogenic drugs.

Naringin treatment improved main clozapine-induced adverse effects in rats; emphasis on weight gain, metabolic abnormalities, and agranulocytosis

Schizophrenia is one of the major neuropsychiatric disorders affecting people worldwide. Unfortunately, currently available antipsychotic medications possess several side effects. Among them, clozapine is one of the atypical antipsychotics prescribed in schizophrenia wing to its blocking effect on dopamine (D2) and serotonin (5-HT_1c ) receptors. However, it has been recently reserved for resistant schizophrenia due to its several side effects. The current research aimed at investigating potential naringin add-on benefit to cease the main side effects of clozapine in ketamine-induced psychosis in rats. In this study, schizophrenia was induced in rats via ketamine administration that could promote neuropathological patterns of schizophrenia. Afterwards, clozapine and naringin were administered to rats in order to improve such effects induced by ketamine. Clozapine administration promoted weight gain, hyperglycemia, dyslipidemia, and agranulocytosis. However, naringin was able to reduce such adverse effects when added to clozapine treatment. Naringin increased total leukocyte count preventing agranulocytosis either when administered alone or in combination with clozapine. In addition, via its metabolic activities, naringin treatment lowered serum total cholesterol and triglycerides levels. Moreover, naringin prevented weight gain when administered. Finally, naringin reduced serum glucose level preventing hyperglycemia associated with clozapine treatment. Collectively, these findings may suggest that naringin possesses a potential add-on benefit to clozapine in treatment of schizophrenia.

Transcriptome analysis of human induced excitatory neurons supports a strong effect of clozapine on cholesterol biosynthesis

Antipsychotics are known to modulate dopamine and other neurotransmitters which is often thought to be the mechanism underlying their therapeutic effects. Nevertheless, other less studied consequences of antipsychotics on neuronal function may contribute to their efficacy. Revealing the complete picture behind their action is of paramount importance for precision medicine and accurate drug selection. Progress in cell engineering allows the generation of induced pluripotent stem cells (iPSCs) and their differentiation to a variety of neuronal types, providing new tools to study antipsychotics. Here we use excitatory cortical neurons derived from iPSCs to explore their response to therapeutic levels of Clozapine as measured by their transcriptomic output, a proxy for neuronal homeostasis. To our surprise, but in agreement with the results of many investigators studying glial-like cells, Clozapine had a very strong effect on cholesterol metabolism. More than a quarter (12) of all annotated cholesterol genes (46) in the genome were significantly changed at FDR < 0.1, all upregulated. This is a 35-fold enrichment with an adjusted p = 8 × 10^-11. Notably no other functional category showed evidence of enrichment. Cholesterol is a major component of the neuronal membrane and myelin but it does not cross the blood brain barrier, it is produced locally mostly by glia but also by neurons. By singling out increased expression of cholesterol metabolism genes as the main response of cortical excitatory neurons to antipsychotics, our work supports the hypothesis that cholesterol metabolism may be a contributing mechanism to the beneficial effects of Clozapine and possibly other antipsychotics.

Sex-Specific Effect of Serum Lipids and Body Mass Index on Psychotic Symptoms, a Cross-Sectional Study of First-Episode Psychosis Patients

Background: Schizophrenia is a disorder with considerable heterogeneity in course and outcomes, which is in part related to the patients' sex. Studies report a link between serum lipids, body mass index (BMI), and therapeutic response. However, the role of sex in these relationships is poorly understood. In a cross-sectional sample of first-episode psychosis (FEP) patients, we investigated if the relationship between serum lipid levels (total cholesterol, HDL-C, LDL-C, and triglycerides), BMI, and symptoms differs between the sexes. Methods: We included 435 FEP patients (males: N = 283, 65%) from the ongoing Thematically Organized Psychosis (TOP) study. Data on clinical status, antipsychotics, lifestyle, serum lipid levels, and BMI were obtained. The Positive and Negative Syndrome Scale (PANSS) and the Calgary Depression Scale for Schizophrenia (CDSS) were used to assess psychotic and depressive symptoms. General linear models were employed to examine the relationship between metabolic variables and symptomatology. Results: We observed a female-specific association between serum HDL-C levels and negative symptoms (B = -2.24, p = 0.03) and between triglycerides levels (B = 1.48, p = 0.04) and BMI (B = 0.27, p = 0.001) with depressive symptoms. When controlling for BMI, only the association between serum HDL-C levels and negative symptoms remained significant. Moreover, the HDL-C and BMI associations remained significant after controlling for demography, lifestyle, and illness-related factors. Conclusion: We found a relationship between metabolic factors and psychiatric symptoms in FEP patients that was sex-dependent.

Cholesteryl ester levels are elevated in the caudate and putamen of Huntington's disease patients

Huntington’s disease (HD) is an autosomal dominant neurodegenerative illness caused by a mutation in the huntingtin gene (HTT) and subsequent protein (mhtt), to which the brain shows a region-specific vulnerability. Disturbances in neural cholesterol metabolism are established in HD human, murine and cell studies; however, cholesteryl esters (CE), which store and transport cholesterol in the brain, have not been investigated in human studies. This study aimed to identify region-specific alterations in the concentrations of CE in HD. The Victorian Brain Bank provided post-mortem tissue from 13 HD subjects and 13 age and sex-matched controls. Lipids were extracted from the caudate, putamen and cerebellum, and CE were quantified using targeted mass spectrometry. ACAT 1 protein expression was measured by western blot. CE concentrations were elevated in HD caudate and putamen compared to controls, with the elevation more pronounced in the caudate. No differences in the expression of ACAT1 were identified in the striatum. No remarkable differences in CE were detected in HD cerebellum. The striatal region-specific differences in CE profiles indicate functional subareas of lipid disturbance in HD. The increased CE concentration may have been induced as a compensatory mechanism to reduce cholesterol accumulation.

Novel Treatment Strategies Targeting Myelin and Oligodendrocyte Dysfunction in Schizophrenia

Oligodendrocytes are the glial cells responsible for the formation of the myelin sheath around axons. During neurodevelopment, oligodendrocytes undergo maturation and differentiation, and later remyelination in adulthood. Abnormalities in these processes have been associated with behavioral and cognitive dysfunctions and the development of various mental illnesses like schizophrenia. Several studies have implicated oligodendrocyte dysfunction and myelin abnormalities in the disorder, together with altered expression of myelin-related genes such as Olig2, CNP, and NRG1. However, the molecular mechanisms subjacent of these alterations remain elusive. Schizophrenia is a severe, chronic psychiatric disorder affecting more than 23 million individuals worldwide and its symptoms usually appear at the beginning of adulthood. Currently, the major therapeutic strategy for schizophrenia relies on the use of antipsychotics. Despite their widespread use, the effects of antipsychotics on glial cells, especially oligodendrocytes, remain unclear. Thus, in this review we highlight the current knowledge regarding oligodendrocyte dysfunction in schizophrenia, compiling data from (epi)genetic studies and up-to-date models to investigate the role of oligodendrocytes in the disorder. In addition, we examined potential targets currently investigated for the improvement of schizophrenia symptoms. Research in this area has been investigating potential beneficial compounds, including the D-amino acids D-aspartate and D-serine, that act as NMDA receptor agonists, modulating the glutamatergic signaling; the antioxidant N-acetylcysteine, a precursor in the synthesis of glutathione, protecting against the redox imbalance; as well as lithium, an inhibitor of glycogen synthase kinase 3β (GSK3β) signaling, contributing to oligodendrocyte survival and functioning. In conclusion, there is strong evidence linking oligodendrocyte dysfunction to the development of schizophrenia. Hence, a better understanding of oligodendrocyte differentiation, as well as the effects of antipsychotic medication in these cells, could have potential implications for understanding the development of schizophrenia and finding new targets for drug development.

Progress in Genetic Polymorphisms Related to Lipid Disturbances Induced by Atypical Antipsychotic Drugs

Metabolic side effects such as weight gain and disturbed lipid metabolism are often observed in the treatment of atypical antipsychotic drugs (AAPDs), which contribute to an excessive prevalence of metabolic syndrome among schizophrenic patients. Great individual differences are observed but the underlying mechanisms are still uncertain. Research on pharmacogenomics indicates that gene polymorphisms involved in the pathways controlling food intake and lipid metabolism may play a significant role. In this review, relevant genes (HTR2C, DRD2, LEP, NPY, MC4R, BDNF, MC4R, CNR1, INSIG2, ADRA2A) and genetic polymorphisms related to metabolic side effects of AAPDs especially dyslipidemia were summarized. Apart from clinical studies, in vitro and in vivo evidence is also analyzed to support related theories. The association of central and peripheral mechanisms is emphasized, enabling the possibility of using peripheral gene expression to predict the central status. Novel methodological development of pharmacogenomics is in urgent need, so as to provide references for individualized medication and further to shed some light on the mechanisms underlying AAPD-induced lipid disturbances.

Second-Generation Antipsychotics and Dysregulation of Glucose Metabolism: Beyond Weight Gain

Second-generation antipsychotics (SGAs) are the cornerstone of treatment for schizophrenia because of their high clinical efficacy. However, SGA treatment is associated with severe metabolic alterations and body weight gain, which can increase the risk of type 2 diabetes and cardiovascular disease, and greatly accelerate mortality. Several underlying mechanisms have been proposed for antipsychotic-induced weight gain (AIWG), but some studies suggest that metabolic changes in insulin-sensitive tissues can be triggered before the onset of AIWG. In this review, we give an outlook on current research about the metabolic disturbances provoked by SGAs, with a particular focus on whole-body glucose homeostasis disturbances induced independently of AIWG, lipid dysregulation or adipose tissue disturbances. Specifically, we discuss the mechanistic insights gleamed from cellular and preclinical animal studies that have reported on the impact of SGAs on insulin signaling, endogenous glucose production, glucose uptake and insulin secretion in the liver, skeletal muscle and the endocrine pancreas. Finally, we discuss some of the genetic and epigenetic changes that might explain the different susceptibilities of SGA-treated patients to the metabolic side-effects of antipsychotics.

Simvastatin improves olanzapine-induced dyslipidemia in rats through inhibiting hepatic mTOR signaling pathway

Second-generation antipsychotic drug (SGA)-induced metabolic abnormalities, such as dyslipidemia, are a major clinical problem for antipsychotic therapy. Accumulated evidences have shown the efficacy of statins in reducing SGA-induced dyslipidemia, but the underlying mechanisms are unclear. In this study, we explored whether mTOR signaling was involved in olanzapine (OLZ)-induced dyslipidemia as well as the lipid-lowering effects of cotreatment of simvastatin (Sim) in rats. Model rats received OLZ (1.0 mg/kg, t.i.d.) for 7 weeks; from the third week a group of model rats were cotreatment of Sim (3.0 mg/kg, t.i.d.) for 5 weeks. We found that OLZ treatment significantly increased the plasma triglyceride (TG) and total cholesterol (TC) levels, and promoted lipid accumulation in the liver, whereas cotreatment of Sim reversed OLZ-induced dyslipidemia. Hepatic mTORC1 and p-mTORC1 expression was accelerated in the OLZ treatment group, with upregulation of mRNA expression of sterol regulatory element-binding protein 1c (SREBP1c) and its target genes, whereas these alterations were ameliorated by Sim cotreatment. In HepG2 cells, rapamycin (a mTOR inhibitor) significantly reduced the OLZ-stimulated hepatocellular lipid contents and weakened the ability of Sim to lower lipids via a mechanism associated with the upregulation of SREBP1c-mediated de novo lipogenesis. Our data suggest that OLZ induces lipid accumulation in both plasma and liver, and Sim ameliorates OLZ-induced lipid metabolic dysfunction through its effects on mTOR signaling via reducing SREBP1c activation and the downregulation of gene expression involved in lipogenesis. These data provide a new insight into the prevention of metabolic side effects induced by antipsychotic drugs.

Host CYP27A1 expression is essential for ovarian cancer progression

There is an urgent need for more effective strategies to treat ovarian cancer. Elevated cholesterol levels are associated with a decreased progression-free survival time (PFS) while statins are protective. 27-Hydroxycholesterol (27HC), a primary metabolite of cholesterol, has been shown to modulate the activities of the estrogen receptors (ERs) and liver x receptors (LXRs) providing a potential mechanistic link between cholesterol and ovarian cancer progression. We found that high expression of CYP27A1, the enzyme responsible for the synthesis of 27HC, was associated with decreased PFS, while high expression of CYP7B1, responsible for 27HC catabolism, was associated with increased PFS. However, 27HC decreased the cellular proliferation of various ovarian cancer cell lines in an LXR-dependent manner. Intriguingly, ID8 grafts were unable to effectively establish in CYP27A1-/- mice, indicating involvement of the host environment. Tumors from mice treated with 27HC had altered myeloid cell composition, and cells from the marrow stem cell lineage were found to be responsible for the effects in CYP27A1-/- mice. While inhibition of CYP27A1 or immune checkpoint did not significantly alter tumor size, their combination did, thereby highlighting this axis as a therapeutic target.

Antipsychotics Promote Metabolic Disorders Disrupting Cellular Lipid Metabolism and Trafficking

Antipsychotics frequently cause obesity and related metabolic disorders that current psychopharmacological/endocrinological theories do not explain consistently. An integrative/alternative theory implies metabolic alterations happening at the cellular level. Many observations in vitro and in vivo, and pivotal observations in humans, point towards chemical properties of antipsychotics, independent of receptor binding characteristics. Being amphiphilic weak bases, antipsychotics can disrupt lysosomal function, affecting cholesterol trafficking; moreover, by chemical mimicry, antipsychotics can inhibit cholesterol biosynthesis. These two molecular adverse effects may trigger a cascade of transcriptional and biochemical events, ultimately reducing available cholesterol while increasing cholesterol precursors and fatty acids. The macroscopic manifestation of these molecular alterations includes decreased high-density lipoprotein and increased very low-density lipoprotein and triglycerides that may translate into obesity and related metabolic disorders.

Atypical antipsychotics-induced metabolic syndrome and nonalcoholic fatty liver disease: a critical review

The atypical antipsychotics (AAPs) have been used as first-line drugs in psychiatric practice for a wide range of psychotic disorders, including schizophrenia and bipolar mania. While effectively exerting therapeutic effects on positive and negative symptoms, as well as cognitive impairments in schizophrenia patients, these drugs are less likely to induce extrapyramidal symptoms compared to typical antipsychotics. However, the increasing application of them has raised questions on their tolerability and adverse effects over the endocrine, metabolic, and cardiovascular axes. Specifically, AAPs are associated to different extents, with weight gain, metabolic syndrome (MetS), and nonalcoholic fatty liver disease (NAFLD). This article summarized clinical evidence showing the metabolic side effects of AAPs in patients with schizophrenia, and experimental evidence of AAPs-induced metabolic side effects observed in animals and cell culture studies. In addition, it discussed potential mechanisms involved in the APPs-induced MetS and NAFLD.

Association between olanzapine treatment and brain cortical thickness and gray/white matter contrast is moderated by cholesterol in psychotic disorders

Altered cortical brain morphology is observed in psychotic disorders. Despite the importance of lipid homeostasis for healthy brain functioning, knowledge about its role in cortical alterations in psychosis is limited. In a sample of patients with psychotic disorders, we investigated the relationship between treatment with olanzapine (OLZ), and cortical thickness and gray/white matter intensity contrast, and the association between these measures and serum lipid levels. We included 33 OLZ users, 19 unmedicated psychotic patients and 76 healthy controls (HC). Data on serum lipids and cortical measures based on MR brain images processed with FreeSurfer were analyzed with General Linear Models. We found that intensity contrast was similar in OLZ users as compared to HC and that the cortex (frontal, orbitofrontal, medial temporal) was thinner in OLZ users (p < 0.05, Bonferroni corrected). An OLZ-specific HDL interaction effect was further found for the pericentral cortical thickness measure (p < 0.05, Bonferroni corrected). Additionally, nominally significant findings indicated similar OLZ-specific interaction effects for cortical thickness in several regions, and an OLZ-specific interaction with LDL for occipital lobe contrast (p < 0.05, uncorrected). Our findings may suggest a drug-related lipid-effect on brain myelination. Experimental studies and replications in different study samples are needed to clarify these complex relationships further.

Decoding the transcriptional programs activated by psychotropic drugs in the brain

Analysis of drug-induced gene expression in the brain has long held the promise of revealing the molecular mechanisms of drug actions as well as predicting their long-term clinical efficacy. However, despite some successes, this promise has yet to be fulfilled. Here, we present an overview of the current state of understanding of drug-induced gene expression in the brain and consider the obstacles to achieving a robust prediction of the properties of psychoactive compounds based on gene expression profiles. We begin with a comprehensive overview of the mechanisms controlling drug-inducible transcription and the complexity resulting from expression of noncoding RNAs and alternative gene isoforms. Particular interest is placed on studies that examine the associations within drug classes with regard to the effects on gene transcription, alterations in cell signaling and neuropharmacological drug properties. While the ability of gene expression signatures to distinguish specific clinical classes of psychotropic and addictive drugs remains unclear, some reports show that under specific constraints, drug properties can be predicted based on gene expression. Such signatures offer a simple and effective way to classify psychotropic drugs and screen novel psychoactive compounds. Finally, we note that the amount of data regarding molecular programs activated in the brain by drug treatment has grown exponentially in recent years and that future advances may therefore come in large part from integrating the currently available high-throughput data sets.

The neuropathological investigation of the brain in a monkey model of autism spectrum disorder with ABCA13 deletion

The precise biological etiology of autism spectrum disorder (ASD) remains unknown. In this study, we investigated the neuropathology of a monkey model of autism Human ABCA13 is the largest ABC transporter protein, with a length of 5058 amino acids and a predicted molecular weight of >450 kDa. However, the function of this protein remains to be elucidated. This protein is thought to be associated with major psychiatric disease. Using this monkey model of autism with an ABCA13 deletion and a mutation of 5HT2c, we neuropathologically investigated the changes in the neuronal formation in the frontal cortex. As a result, the neuronal formation in the cortex was found to be disorganized with regard to the neuronal size and laminal distribution in the ABCA13 deletion monkey. The catecholaminergic and GABAergic neuronal systems, serotoninergic neuronal formation (5HT2c) were also found to be impaired by an immunohistochemical evaluation. This study suggested that ABCA13 deficit induces the impairment of neuronal maturation or migration, and the function of the neuronal network. This protein might thus play a role in the neurodevelopmental function of the central nervous system and the dysfunction of this protein may be a pathophysiological cause of mental disorders including autism.

Influence of polygenic risk scores on lipid levels and dyslipidemia in a psychiatric population receiving weight gain-inducing psychotropic drugs

OBJECTIVES

Dyslipidemia represents a major health issue in psychiatry. We determined whether weighted polygenic risk scores (wPRSs) combining multiple single-nucleotide polymorphisms (SNPs) associated with lipid levels in the general population are associated with lipid levels [high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (TC), and triglycerides] and/or dyslipidemia in patients receiving weight gain-inducing psychotropic drugs. We also determined whether genetics improve the predictive power of dyslipidemia.

PATIENTS AND METHODS

The influence of wPRS on lipid levels was firstly assessed in a discovery psychiatric sample (n=332) and was then tested for replication in an independent psychiatric sample (n=140). The contribution of genetic markers to predict dyslipidemia was evaluated in the combined psychiatric sample.

RESULTS

wPRSs were significantly associated with the four lipid traits in the discovery (P≤0.02) and in the replication sample (P≤0.03). Patients whose wPRS was higher than the median wPRS had significantly higher LDL, TC, and triglyceride levels (0.20, 0.32 and 0.26 mmol/l, respectively; P≤0.004) and significantly lower HDL levels (0.13 mmol/l; P<0.0001) compared with others. Adding wPRS to clinical data significantly improved dyslipidemia prediction of HDL (P=0.03) and a trend for improvement was observed for the prediction of TC dyslipidemia (P=0.08).

CONCLUSION

Population-based wPRSs have thus significant effects on lipid levels in the psychiatric population. As genetics improved the predictive power of dyslipidemia development, only 24 patients need to be genotyped to prevent the development of one case of HDL hypocholesterolemia. If confirmed by further prospective investigations, the present results could be used for individualizing psychotropic treatment.

Replication of rs300774, a genetic biomarker near ACP1, associated with suicide attempts in patients with schizophrenia: Relation to brain cholesterol biosynthesis

The aim of this study was to determine if three biomarkers for suicide attempts previously identified and replicated in a genome-wide association (GWAS) study of bipolar disorder (BD) suicide attempters also predicted suicide attempts in patients prospectively diagnosed with schizophrenia (SCZ) or schizoaffective disorder (SAD). 162 genetically-verified Caucasian patients with SCZ or SAD were phenotyped for presence (45.7%) or absence of a lifetime suicide attempt. Three single nucleotide polymorphisms (SNPs) were genotyped or partially imputed from a GWAS dataset. After controlling for genetic architecture and gender, we replicated rs300774 (p = 0.012), near ACP1 (acid phosphatase 1), the top predictor of suicide attempts in the BD study. The result of Willour et al. (2012) was replicated in males (p = 0.046) but not in females (p = 0.205). The other two SNPs, rs7296262, and rs10437629, were not associated with suicide attempts in this study. rs300774 could be a cis-eQTL for ACP1, with minor allele carriers having lower expression levels (p = 0.002). This SNP also functioned as a trans-eQTL for genes related to cholesterol biosynthesis and the wnt-β-catenin pathway (p ≤ 0.0001). Further, co-expression analysis of candidate genes in brain suggested ACP1 is important to the regulation of a number of brain mechanisms linked to suicide, including cholesterol synthesis, β-catenin-mediated signaling pathway, serotonin, GABA, and the stress response via ARHGAP35 (p190rhogap), a repressor of glucocorticoid receptor (NR3C1) transcription. This study provides an additional validation of rs300774 as a potential transdiagnostic biomarker for suicide attempts and evidence that ACP1 may have an important role in regulation of the multiple systems associated with suicide.

Haloperidol induces pharmacoepigenetic response by modulating miRNA expression, global DNA methylation and expression profiles of methylation maintenance genes and genes involved in neurotransmission in neuronal cells

Introduction

Haloperidol has been extensively used in various psychiatric conditions. It has also been reported to induce severe side effects. We aimed to evaluate whether haloperidol can influence host methylome, and if so what are the possible mechanisms for it in neuronal cells. Impact on host methylome and miRNAs can have wide spread alterations in gene expression, which might possibly help in understanding how haloperidol may impact treatment response or induce side effects.

Methods

SK-N-SH, a neuroblasoma cell line was treated with haloperidol at 10μm concentration for 24 hours and global DNA methylation was evaluated. Methylation at global level is maintained by methylation maintenance machinery and certain miRNAs. Therefore, the expression of methylation maintenance genes and their putative miRNA expression profiles were assessed. These global methylation alterations could result in gene expression changes. Therefore genes expressions for neurotransmitter receptors, regulators, ion channels and transporters were determined. Subsequently, we were also keen to identify a strong candidate miRNA based on biological and in-silico approach which can reflect on the pharmacoepigenetic trait of haloperidol and can also target the altered neuroscience panel of genes used in the study.

Results

Haloperidol induced increase in global DNA methylation which was found to be associated with corresponding increase in expression of various epigenetic modifiers that include DNMT1, DNMT3A, DNMT3B and MBD2. The expression of miR-29b that is known to putatively regulate the global methylation by modulating the expression of epigenetic modifiers was observed to be down regulated by haloperidol. In addition to miR-29b, miR-22 was also found to be downregulated by haloperidol treatment. Both these miRNA are known to putatively target several genes associated with various epigenetic modifiers, pharmacogenes and neurotransmission. Interestingly some of these putative target genes involved in neurotransmission were observed to be upregulated while CHRM2 gene expression was down regulated.

Conclusions

Haloperidol can influence methylation traits thereby inducing a pharmacoepigenomic response, which seems to be regulated by DNMTs and their putative miRNA expression. Increased methylation seems to influence CHRM2 gene expression while microRNA could influence neurotransmission, pharmacogene expression and methylation events. Altered expression of various therapeutically relevant genes and miRNA expression, could account for their role in therapeutic response or side effects.

Overexpression of Insig-2 inhibits atypical antipsychotic-induced adipogenic differentiation and lipid biosynthesis in adipose-derived stem cells

Atypical antipsychotics (AAPs) are considered to possess superior efficacy for treating both the positive and negative symptoms of schizophrenia; however, AAP use often causes excessive weight gain and metabolic abnormalities. Recently, several reports have demonstrated that AAPs activate sterol regulatory element-binding protein (SREBP). SREBP, SREBP cleavage-activating protein (SCAP) and insulin-induced gene (Insig) regulate downstream cholesterol and fatty acid biosynthesis. In this study, we explored the effects of clozapine, olanzapine and risperidone on SREBP signaling and downstream lipid biosynthesis genes in the early events of adipogenic differentiation in adipose-derived stem cells (ASCs). After the induction of adipogenic differentiation for 2 days, all AAPs, notably clozapine treatment for 3 and 7 days, enhanced the expression of SREBP-1 and its downstream lipid biosynthesis genes without dexamethasone and insulin supplementation. Simultaneously, protein level of SREBP-1 was significantly enhanced via inhibition of Insig-2 expression. By contrast, SREBP-1 activation was suppressed when Insig-2 expression was upregulated by transfection with Insig-2 plasmid DNA. In summary, our results indicate that AAP treatment, notably clozapine treatment, induces early-stage lipid biosynthesis in ASCs. Such abnormal lipogenesis can be reversed when Insig-2 expression was increased, suggesting that Insig/SCAP/SREBP signaling may be a therapeutic target for AAP-induced weight gain and metabolic abnormalities.

Lack of Ovarian Secretions Reverts the Anabolic Action of Olanzapine in Female Rats

BACKGROUND

Olanzapine is an orexigenic antipsychotic drug associated with serious metabolic adverse effects in humans. Development of valid rodent models for antipsychotic-induced metabolic adverse effects is hampered by the fact that such effects occur in females only. Estradiol is a predominant female hormone that regulates energy balance. We hypothesized that the female-specific hyperphagia and weight gain induced by olanzapine in the rat are dependent on the presence of estrogens.

METHODS

Female sham-operated or ovariectomized rats were treated with a single injection of olanzapine depot formulation. Food intake, body weight, plasma lipids, lipogenic gene expression, energy expenditure, and thermogenic markers including brown adipose tissue uncoupling protein 1 protein levels were measured. Olanzapine was also administered to ovariectomized rats receiving estradiol replacement via the subcutaneous (peripheral) or intracerebroventricular route.

RESULTS

Orexigenic effects of olanzapine were lost in ovariectomized female rats. Ovariectomized rats treated with olanzapine had less pronounced weight gain than expected from their food intake. Accordingly, brown adipose tissue temperature and protein levels of uncoupling protein 1 were elevated. Replacement in ovariectomized rats with either peripherally or centrally administered estradiol reduced food intake and body weight. Cotreatment with olanzapine blocked the anorexigenic effect of peripheral, but not central estradiol.

CONCLUSIONS

Our results indicate that the ovarian hormone estradiol plays an important role in olanzapine-induced hyperphagia in female rats and pinpoint the complex effects of olanzapine on the balance between energy intake and thermogenesis.

Genetic evidence for a role of the SREBP transcription system and lipid biosynthesis in schizophrenia and antipsychotic treatment

Schizophrenia is a serious psychotic disorder, with disabling symptoms and markedly reduced life expectancy. The onset is usually in late adolescence or early adulthood, which in time overlaps with the maturation of the brain including the myelination process. Interestingly, there seems to be a link between myelin abnormalities and schizophrenia. The oligodendrocyte-derived myelin membranes in the CNS are highly enriched for lipids (cholesterol, phospholipids and glycosphingolipids), thereby pointing at lipid homeostasis as a relevant target for studying the genetics and pathophysiology of schizophrenia. The biosynthesis of fatty acids and cholesterol is regulated by the sterol regulatory element binding protein (SREBP) transcription factors SREBP1 and SREBP2, which are encoded by the SREBF1 and SREBF2 genes on chromosome 17p11.2 and 22q13.2, respectively. Here we review the evidence for the involvement of SREBF1 and SREBF2 as genetic risk factors in schizophrenia and discuss the role of myelination and SREBP-mediated lipid biosynthesis in the etiology, pathophysiology and drug treatment of schizophrenia.

Therapeutic efficacy of atypical antipsychotic drugs by targeting multiple stress-related metabolic pathways

Schizophrenia (SZ) is considered to be a multifactorial brain disorder with defects involving many biochemical pathways. Patients with SZ show variable responses to current pharmacological treatments of SZ because of the heterogeneity of this disorder. Stress has a significant role in the pathophysiological pathways and therapeutic responses of SZ. Atypical antipsychotic drugs (AAPDs) can modulate the stress response of the hypothalamic-pituitary-adrenal (HPA) axis and exert therapeutic effects on stress by targeting the prefrontal cortex (PFC) and hippocampus. To evaluate the effects of AAPDs (such as clozapine, risperidone and aripiprazole) on stress, we compared neurochemical profile variations in the PFC and hippocampus between rat models of chronic unpredictable mild stress (CUMS) for HPA axis activation and of long-term dexamethasone exposure (LTDE) for HPA axis inhibition, using an ultraperformance liquid chromatography-mass spectrometry (UPLC-MS/MS)-based metabolomic approach and a multicriteria assessment. We identified a number of stress-induced biomarkers comprising creatine, choline, inosine, hypoxanthine, uric acid, allantoic acid, lysophosphatidylcholines (LysoPCs), phosphatidylethanolamines (PEs), corticosterone and progesterone. Specifically, pathway enrichment and correlation analyses suggested that stress induces oxidative damage by disturbing the creatine-phosphocreatine circuit and purine pathway, leading to excessive membrane breakdown. Moreover, our data suggested that the AAPDs tested partially restore stress-induced deficits by increasing the levels of creatine, progesterone and PEs. Thus, the present findings provide a theoretical basis for the hypothesis that a combined therapy using adenosine triphosphate fuel, antioxidants and omega-3 fatty acids as supplements may have synergistic effects on the therapeutic outcome following AAPD treatment.

Neuronal Activity-Induced Sterol Regulatory Element Binding Protein-1 (SREBP1) is Disrupted in Dysbindin-Null Mice-Potential Link to Cognitive Impairment in Schizophrenia

Schizophrenia is a chronic debilitating neuropsychiatric disorder that affects about 1 % of the population. Dystrobrevin-binding protein 1 (DTNBP1 or dysbindin) is one of the Research Domain Constructs (RDoC) associated with cognition and is significantly reduced in the brain of schizophrenia patients. To further understand the molecular underpinnings of pathogenesis of schizophrenia, we have performed microarray analyses of the hippocampi from dysbindin knockout mice, and found that genes involved in the lipogenic pathway are suppressed. Moreover, we discovered that maturation of a master transcriptional regulator for lipid synthesis, sterol regulatory element binding protein-1 (SREBP1) is induced by neuronal activity, and is required for induction of the immediate early gene ARC (activity-regulated cytoskeleton-associated protein), necessary for synaptic plasticity and memory. We found that nuclear SREBP1 is dramatically reduced in dysbindin-1 knockout mice and postmortem brain tissues from human patients with schizophrenia. Furthermore, activity-dependent maturation of SREBP1 as well as ARC expression were attenuated in dysbindin-1 knockout mice, and these deficits were restored by an atypical antipsychotic drug, clozapine. Together, results indicate an important role of dysbindin-1 in neuronal activity induced SREBP1 and ARC, which could be related to cognitive deficits in schizophrenia.

Statin prescribing for people with severe mental illnesses: a staggered cohort study of 'real-world' impacts

OBJECTIVES

To estimate the 'real-world effectiveness of statins for primary prevention of cardiovascular disease (CVD) and for lipid modification in people with severe mental illnesses (SMI), including schizophrenia and bipolar disorder.

DESIGN

Series of staggered cohorts. We estimated the effect of statin prescribing on CVD outcomes using a multivariable Poisson regression model or linear regression for cholesterol outcomes.

SETTING

587 general practice (GP) surgeries across the UK reporting data to The Health Improvement Network.

PARTICIPANTS

All permanently registered GP patients aged 40-84 years between 2002 and 2012 who had a diagnosis of SMI. Exclusion criteria were pre-existing CVD, statin-contraindicating conditions or a statin prescription within the 24 months prior to the study start.

EXPOSURE

One or more statin prescriptions during a 24-month 'baseline' period (vs no statin prescription during the same period).

MAIN OUTCOME MEASURES

The primary outcome was combined first myocardial infarction and stroke. All-cause mortality and total cholesterol concentration were secondary outcomes.

RESULTS

We identified 2944 statin users and 42 886 statin non-users across the staggered cohorts. Statin prescribing was not associated with significant reduction in CVD events (incident rate ratio 0.89; 95% CI 0.68 to 1.15) or all-cause mortality (0.89; 95% CI 0.78 to 1.02). Statin prescribing was, however, associated with statistically significant reductions in total cholesterol of 1.2 mmol/L (95% CI 1.1 to 1.3) for up to 2 years after adjusting for differences in baseline characteristics. On average, total cholesterol decreased from 6.3 to 4.6 in statin users and 5.4 to 5.3 mmol/L in non-users.

CONCLUSIONS

We found that statin prescribing to people with SMI in UK primary care was effective for lipid modification but not CVD events. The latter finding may reflect insufficient power to detect a smaller effect size than that observed in randomised controlled trials of statins in people without SMI.

INSIG2 polymorphism and weight gain, dyslipidemia and serum adiponectin in Finnish patients with schizophrenia treated with clozapine

Aim: To investigate INSIG2's association with obesity, weight change and serum lipid profile during clozapine treatment. Materials & methods: Subjects with schizophrenia (n = 190) were genotyped, identifying seven SNPs. Genetic risk scores (GRSs) were calculated to adiponectin, high-density lipoprotein cholesterol, triglycerides and weight gain. Results: In the model for weight gain, SNPs rs12151787, rs17047733 and rs10490626 were selected. Explanatory variables were BMI (p = 5.05 × 10-5), age (p = 0.003) and GRS (p = 2.81 × 10-5, p = 0.0002 after permutation). No GRS resulted for adiponectin or high-density lipoprotein cholesterol. Rs2161829 and rs10490620 were selected for triglycerides; this GRS was insignificant after permutation. Conclusion: INSIG2 plays a role in weight gain and obesity during clozapine treatment.

Berberine Alleviates Olanzapine-Induced Adipogenesis via the AMPKα-SREBP Pathway in 3T3-L1 Cells

The aim of this study was to investigate the mechanisms underlying the inhibitory effects of berberine (BBR) on olanzapine (OLZ)-induced adipogenesis in a well-replicated 3T3-L1 cell model. Oil-Red-O (ORO) staining showed that BBR significantly decreased OLZ-induced adipogenesis. Co-treatment with OLZ and BBR decreased the accumulation of triglyceride (TG) and total cholesterol (TC) by 55.58% ± 3.65% and 49.84% ± 8.31%, respectively, in 3T3-L1 adipocytes accompanied by reduced expression of Sterol regulatory element binding proteins 1 (SREBP1), fatty acid synthase (FAS), peroxisome proliferator activated receptor-γ (PPARγ), SREBP2, low-density lipoprotein receptor (LDLR), and hydroxymethylglutaryl-coenzyme A reductase (HMGR) genes compared with OLZ alone. Consistently, the co-treatment downregulated protein levels of SREBP1, SREBP2, and LDLR by 57.71% ± 9.42%, 73.05% ± 11.82%, and 59.46% ± 9.91%, respectively. In addition, co-treatment reversed the phosphorylation level of AMP-activated protein kinase-α (AMPKα), which was reduced by OLZ, determined via the ratio of pAMPKα:AMPKα (94.1%) compared with OLZ alone. The results showed that BBR may prevent lipid metabolism disorders caused by OLZ by reversing the degree of SREBP pathway upregulated and the phosphorylation of AMPKα downregulated. Collectively, these results indicated that BBR could be used as a potential adjuvant to prevent dyslipidemia and obesity caused by the use of second-generation antipsychotic medication.

Necroptosis-like Neuronal Cell Death Caused by Cellular Cholesterol Accumulation

Aberrant cellular accumulation of cholesterol is associated with neuronal lysosomal storage disorders such as Niemann-Pick disease Type C (NPC). We have shown previously that l-norephedrine (l-Nor), a sympathomimetic amine, induces necrotic cell death associated with massive cytoplasmic vacuolation in SH-SY5Y human neuroblastoma cells. To reveal the molecular mechanism underling necrotic neuronal cell death caused by l-Nor, we examined alterations in the gene expression profile of cells during l-Nor exposure. DNA microarray analysis revealed that the gene levels for cholesterol transport (LDL receptor and NPC2) as well as cholesterol biosynthesis (mevalonate pathway enzymes) are increased after exposure to 3 mm l-Nor for ∼6 h. Concomitant with this observation, the master transcriptional regulator of cholesterol homeostasis, SREBP-2, is activated by l-Nor. The increase in cholesterol uptake as well as biosynthesis is not accompanied by an increase in cholesterol in the plasma membrane, but rather by aberrant accumulation in cytoplasmic compartments. We also found that cell death by l-Nor can be suppressed by nec-1s, an inhibitor of a regulated form of necrosis, necroptosis. Abrogation of SREBP-2 activation by the small molecule inhibitor betulin or by overexpression of dominant-negative SREBP-2 efficiently reduces cell death by l-Nor. The mobilization of cellular cholesterol in the presence of cyclodextrin also suppresses cell death. These results were also observed in primary culture of striatum neurons. Taken together, our results indicate that the excessive uptake as well as synthesis of cholesterol should underlie neuronal cell death by l-Nor exposure, and suggest a possible link between lysosomal cholesterol storage disorders and the regulated form of necrosis in neuronal cells.

Lack of association of SNPs from the FADS1-FADS2 gene cluster with major depression or suicidal behavior

Fatty acid desaturase genes (FADS1-FADS2) encode desaturases participating in the biosynthesis of long-chain polyunsaturated fatty acids. As long-chain polyunsaturated fatty acids are implicated in major depressive disorder (MDD) and suicide risk, and as both are partly heritable, we studied the association of FADS1-FADS2 polymorphisms with MDD (635 cases, 480 controls) and suicide attempt status (291 attempters, 344 MDD nonattempters). Eighteen FADS-related single-nucleotide polymorphisms were genotyped from Caucasians enrolled in Madrid (n=791) or New York City (n=324) and entered as predictors into logistic regression analyses with diagnostic group or suicide attempt history as outcomes and location and sex as covariates. No associations were observed between any single-nucleotide polymorphisms and diagnosis or attempt status. As statistical power was adequate, we conclude that FADS1-FADS2 genetic variants may not be a common determinant of MDD.

Association between SCAP and SREBF1 gene polymorphisms and metabolic syndrome in schizophrenia patients treated with atypical antipsychotics

OBJECTIVES

The use of atypical antipsychotics (AAPs) in the treatment of schizophrenia has been relevant because of the high prevalence of metabolic syndrome (MetS). The sterol-regulatory element-binding protein (SREBP) pathway may contribute to the underlying pathophysiology of AAP-induced metabolic adverse effects. We explored the association between the variants of the sterol-regulatory element-binding transcription factor-1 (SREBF1) gene and the SREBP cleavage-activation protein (SCAP) gene with AAP-induced MetS in a genetic case-control study.

METHODS

Eleven single nucleotide polymorphisms (SNPs) of SREBF1 and five of SCAP were genotyped in a Han Chinese population in Beijing, China: a sample of 722 schizophrenia patients on monotherapy with AAPs (clozapine, olanzapine or risperidone). Metabolic parameters were collected and evaluated for MetS criteria.

RESULTS

The rs11654081 T-allele of the SREBF1 gene was significantly associated with an increased risk for MetS after correction (P = 0.019, odds ratio, OR =2.56, 95% confidence interval, CI: 1.4 4-4.54). The rs11654081-TT genotype appeared more frequently in MetS than in non-MetS after correction (P = 0.026, OR =2.37, 95% CI: 1.3 6-4.12). SCAP polymorphisms with drug-induced MetS were negative in this study.

CONCLUSIONS

The genetic polymorphisms of SREBF1 could play a role in the mechanism for interindividual variation of AAP-induced MetS.

Investigation of 7-dehydrocholesterol reductase pathway to elucidate off-target prenatal effects of pharmaceuticals: a systematic review

Mendelian diseases contain important biological information regarding developmental effects of gene mutations that can guide drug discovery and toxicity efforts. In this review, we focus on Smith–Lemli–Opitz syndrome (SLOS), a rare Mendelian disease characterized by compound heterozygous mutations in 7-dehydrocholesterol reductase (DHCR7) resulting in severe fetal deformities. We present a compilation of SLOS-inducing DHCR7 mutations and the geographic distribution of those mutations in healthy and diseased populations. We observed that several mutations thought to be disease causing occur in healthy populations, indicating an incomplete understanding of the condition and highlighting new research opportunities. We describe the functional environment around DHCR7, including pharmacological DHCR7 inhibitors and cholesterol and vitamin D synthesis. Using PubMed, we investigated the fetal outcomes following prenatal exposure to DHCR7 modulators. First-trimester exposure to DHCR7 inhibitors resulted in outcomes similar to those of known teratogens (50 vs 48% born-healthy). DHCR7 activity should be considered during drug development and prenatal toxicity assessment.

Improvements in body composition, anthropometric measurements and lipid profile following discontinuation of clozapine

BACKGROUND

Metabolic syndrome (obesity, glucose intolerance, insulin resistance and dyslipidaemia) is a well-known adverse effect of most antipsychotics. It is particularly common in patients treated with olanzapine and clozapine. Currently, the mechanisms underlying its development are not completely understood.

CASE REPORT

We present a case of improved body composition (reduced amount of total body fat and visceral adipose tissue), anthropometric measurements (body weight, waist, abdominal and hip circumferences) and lipid profile in a 31-year-old man with schizophrenia following discontinuation of clozapine. During a combined treatment with clozapine, flupentixol and ziprasidone, a routine laboratory test revealed a severe dyslipidaemia (triglycerides > 1800 mg/dL; > 20.3 mmol/L), despite previous lipid-lowering therapy. This abnormality completely recovered after clozapine has been discontinued.

CONCLUSIONS

Clozapine may cause severe, but reversible metabolic abnormalities, including obesity and hypertriglyceridaemia. Atypical antipsychotic-related lipid abnormalities may have a very rapid onset, occur in relatively young patients, with severe lipid derangements and have potential serious complications. This case confirms how important is to monitor metabolic parameters in patients taking antipsychotics. Discontinuation or switching to another antipsychotic medication may improve components of the metabolic syndrome.

A potential mechanism underlying atypical antipsychotics-induced lipid disturbances

Previous findings suggested that a four-protein complex, including sterol-regulatory element-binding protein (SREBP), SREBP-cleavage-activating protein (SCAP), insulin-induced gene (INSIG) and progesterone receptor membrane component 1 (PGRMC1), within the endoplasmic reticulum appears to be an important regulator responsible for atypical antipsychotic drug (AAPD)-induced lipid disturbances. In the present study, effects of typical antipsychotic drug and AAPDs as well as treatment outcome of steroid antagonist mifepristone (MIF) on the PGRMC1/INSIG/SCAP/SREBP pathway were investigated in rat liver using real-time quantitative polymerase chain reaction (qPCR) and western blot analysis. In addition, serum triacylglycerol, total cholesterol, free fatty acids and various hormones including progesterone, corticosterone and insulin were measured simultaneously. Following treatment with clozapine or risperidone, both lipogenesis and cholesterogenesis were enhanced via inhibition of PGRMC1/INSIG-2 and activation of SCAP/SREBP expressions. Such metabolic disturbances, however, were not demonstrated in rats treated with aripiprazole (ARI) or haloperidol (HAL). Moreover, the add-on treatment of MIF was effective in reversing the AAPD-induced lipid disturbances by upregulating the expression of PGRMC1/INSIG-2 and subsequent downregulation of SCAP/SREBP. Taken together, our findings suggest that disturbances in lipid metabolism can occur at an early stage of AAPD treatment before the presence of weight gain. Such metabolic defects can be modified by an add-on treatment of steroid antagonist MIF enhancing the PGRMC1 pathway. Thus, it is likely that PGRMC1/INSIG-2 signaling may be a therapeutic target for AAPD-induced weight gain.

Olanzapine depot exposure in male rats: Dose-dependent lipogenic effects without concomitant weight gain

Treatment with second-generation antipsychotic agents such as olanzapine frequently results in metabolic adverse effects, e.g. hyperphagia, weight gain and dyslipidaemia in patients of both genders. The molecular mechanisms underlying metabolic adverse effects are still largely unknown, and studies in rodents represent an important approach in their exploration. However, the validity of the rodent model is hampered by the fact that antipsychotics induce weight gain in female, but not male, rats. When administered orally, the short half-life of olanzapine in rats prevents stable plasma concentrations of the drug. We recently showed that a single intramuscular injection of long-acting olanzapine formulation yields clinically relevant plasma concentrations accompanied by several dysmetabolic features in the female rat. In the current study, we show that depot injections of 100-250 mg/kg olanzapine yielded clinically relevant plasma olanzapine concentrations also in male rats. In spite of transient hyperphagia, however, olanzapine resulted in weight loss rather than weight gain. The resultant negative feed efficiency was accompanied by a slight elevation of thermogenesis markers in brown adipose tissue for the highest olanzapine dose, but the olanzapine-related reduction in weight gain remains to be explained. In spite of the absence of weight gain, an olanzapine dose of 200mg/kg or above induced significantly elevated plasma cholesterol levels and pronounced activation of lipogenic gene expression in the liver. These results confirm that olanzapine stimulates lipogenic effects, independent of weight gain, and raise the possibility that endocrine factors may influence gender specificity of metabolic effects of antipsychotics in the rat.