Pharmacological treatment of schizophrenia: a critical review of the pharmacology and clinical effects of current and future therapeutic agents

Association Between ApoA1 Gene Polymorphisms and Antipsychotic Drug-Induced Dyslipidemia in Schizophrenia

PURPOSE

Dyslipidemia frequently occurs in schizophrenia patients treated with antipsychotic drugs (APDs), especially atypical APDs. Apolipoprotein A1 (ApoA1) plays a key role in lipid metabolism. The aim of this study was to investigate whether ApoA1 gene polymorphisms are associated with APD-induced dyslipidemia in schizophrenia patients.

PATIENTS AND METHODS

A total of 1987 patients with schizophrenia were enrolled in this study. Serum lipid profiles were determined with a biochemistry analyzer. Genotyping for the rs5072 polymorphism of ApoA1 was performed with TaqMan assay. Logistic regression analysis was carried out to evaluate the relationship between ApoA1 gene polymorphisms and APD-induced dyslipidemia. The effects of drug classification (typical vs atypical APD) and drug regimen (monotherapy vs combination therapy) on serum lipid levels were also analyzed.

RESULTS

A significant association was found between rs5072 and triglyceride (TG) levels in the recessive model of the logistic regression analysis (adjusted odds ratio [OR]=1.50, 95% confidence interval [CI]: 1.03, 2.17; P<0.05). TG level was significantly higher in patients treated with combination therapy (1.03 (0.71, 1.51) mmol/l) compared to monotherapy (0.93 (0.67, 1.43) mmol/l) and was also associated with sex. There were significant differences in TG levels among the three genotypes of ApoA1 rs5072 (GG, GA, and AA) in the whole study population and in patients treated with atypical APDs.

CONCLUSION

The ApoA1 rs5072 variant is associated with dysregulated TG metabolism in schizophrenia patients treated with APDs, which may increase susceptibility to dyslipidemia.

The recent outbreaks of human coronaviruses: A medicinal chemistry perspective

Coronaviruses (CoVs) infect both humans and animals. In humans, CoVs can cause respiratory, kidney, heart, brain, and intestinal infections that can range from mild to lethal. Since the start of the 21st century, three β-coronaviruses have crossed the species barrier to infect humans: severe-acute respiratory syndrome (SARS)-CoV-1, Middle East respiratory syndrome (MERS)-CoV, and SARS-CoV-2 (2019-nCoV). These viruses are dangerous and can easily be transmitted from human to human. Therefore, the development of anticoronaviral therapies is urgently needed. However, to date, no approved vaccines or drugs against CoV infections are available. In this review, we focus on the medicinal chemistry efforts toward the development of antiviral agents against SARS-CoV-1, MERS-CoV, SARS-CoV-2, targeting biochemical events important for viral replication and its life cycle. These targets include the spike glycoprotein and its host-receptors for viral entry, proteases that are essential for cleaving polyproteins to produce functional proteins, and RNA-dependent RNA polymerase for viral RNA replication.

The Influence of Substance Use on Side Effects of Olanzapine, Quetiapine, Risperidone, and Ziprasidone in Psychosis

BACKGROUND

Side effects restrict the optimal use of antipsychotics. Little is known about the influence of substance use on side effects. The aim of this study was to compare antipsychotic side effects in patients with psychosis with and without substance use, while also taking medication history and diagnosis into consideration.

METHODS

All patients (n = 226, mean age 34, females 33%) diagnosed with schizophrenia spectrum disorders (SSD; F20-F29) or other psychosis (F30-F32; F10-F19), were treated with olanzapine, quetiapine, risperidone or ziprasidone, and were assessed at baseline, 4-weeks, 14-weeks, and 27-weeks. The UKU-Side Effects Self-Rating Scale version was used to evaluate the side effect profiles, and the information on substance use was based on the Clinician Drug Use Scale.

RESULTS

At baseline, 30% of the patients used substances, 54% were diagnosed with SSD, and 47% were antipsychotic naïve. The occurrence of side effects in total was not different in patients with substance use compared to without after 4-weeks of treatment, nor in the follow-up period. At 4-weeks there were some group differences in relation to substance use, diagnosis, and medication history for single side effects. Patients with substance use showed more increased dream activity, less reduced salivation, and more gynecomastia. Patients with SSD showed less neurological side effects, orgasm dysfunction, and tension/inner unrest. The medication naïve patients showed increased hypokinesia/akinesia.

CONCLUSION

Substance use alone does not influence the general magnitude of side effects of antipsychotic medication and does not indicate a different prescription practice in patients with psychosis and substance use.

Acting Before; A Combined Strategy to Counteract the Onset and Progression of Dementia

Brain aging and aging-related neurodegenerative disorders are posing a significant challenge for health systems worldwide. To date, most of the therapeutic efforts aimed at counteracting dementiarelated behavioral and cognitive impairment have been focused on addressing putative determinants of the disease, such as β-amyloid or tau. In contrast, relatively little attention has been paid to pharmacological interventions aimed at restoring or promoting the synaptic plasticity of the aging brain. The review will explore and discuss the most recent molecular, structural/functional, and behavioral evidence that supports the use of non-pharmacological approaches as well as cognitive-enhancing drugs to counteract brain aging and early-stage dementia.

BDNF serum levels and cognitive improvement in drug-naive first episode patients with schizophrenia: A prospective 12-week longitudinal study

Abnormal brain-derived neurotrophic factor (BDNF) levels are involved in cognitive decline in patients with schizophrenia. The role of atypical antipsychotic risperidone in improving cognitive function remains unclear. The study aimed to investigate the effect of risperidone monotherapy on cognitive impairment in drug-naïve first-episode (DNFE) patients with schizophrenia and whether BDNF levels were correlated to the improvement of cognition. 354 DNFE patients and 152 healthy controls were recruited, and we compared their serum BDNF levels and cognition shown on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). High and low BDNF subgroups were defined by median split. Then, 211 patients were treated with risperidone monotherapy for 12 weeks, and their serum BDNF levels and cognition were measured again after treatment. DNFE patients had poorer cognitive functions and lower BDNF levels compared to controls. Lower BDNF levels were correlated with delayed memory in DNFE patients with high baseline BDNF levels. After 12 weeks of treatment, risperidone significantly improved immediate memory, delayed memory and RBANS total scores and BDNF levels were slightly increased. In patients with low-BDNF, BDNF levels were significantly increased after risperidone treatment, while in patients with high-BDNF, BDNF levels were significantly decreased. In addition, baseline BDNF levels were associated with improvement of delayed memory and were a prognostic factor for the improvement of the delayed memory and RBANS total score in patients with high-BDNF. Our result suggests risperidone treatment can partially improve certain domains of the cognitive impairment and baseline BDNF levels are related to cognitive response to risperidone in DNFE patients with schizophrenia.

Psychosocial interventions in schizophrenia: Focus on guidelines

BACKGROUND

Schizophrenia is a lifelong condition with acute exacerbations and varying degrees of functional disability. Acute and long-term treatments are based on antipsychotic drugs, even if some domains of personal and social functioning are not addressed by psychopharmacotherapy. In fact, psychosocial interventions show a positive impact on patient's functioning and clinical outcome. In addition, psychosocial interventions are significantly associated with a lower number of relapses and hospitalizations in schizophrenia.

METHODS

An analytical review of the International Guidelines on Psychosocial Interventions in Schizophrenia has been performed; we included the National Institute for Health and Care Excellence (NICE) guidelines, the Scottish Intercollegiate Guidelines Network (SIGN) guidelines, the Royal Australian and New Zealand College of Psychiatrists (RANZCP) guidelines, the Schizophrenia Patient Outcomes Research Team (PORT) guidelines and the American Psychiatric Association (APA) guidelines.

RESULTS

The international guidelines recommend psychosocial interventions as supportive treatments alongside pharmaceutical or psychotherapeutic ones.

CONCLUSION

More research studies need to be conducted and included in the updated version of the international guidelines to confirm the effectiveness of psychosocial interventions in the long-term outcome of schizophrenia.

Dopamine, Cognitive Impairments and Second-Generation Antipsychotics: From Mechanistic Advances to More Personalized Treatments

The pharmacological treatment of cognitive impairments associated with schizophrenia is still a major unmet clinical need. Indeed, treatments with available antipsychotics generate highly variable cognitive responses among patients with schizophrenia. This has led to the general assumption that antipsychotics are ineffective on cognitive impairment, although personalized medicine and drug repurposing approaches might scale down this clinical issue. In this scenario, evidence suggests that cognitive improvement exerted by old and new atypical antipsychotics depends on dopaminergic mechanisms. Moreover, the newer antipsychotics brexpiprazole and cariprazine, which might have superior clinical efficacy on cognitive deficits over older antipsychotics, mainly target dopamine receptors. It is thus reasonable to assume that despite more than 50 years of elusive efforts to develop novel non-dopaminergic antipsychotics, dopamine receptors remain the most attractive and promising pharmacological targets in this field. In the present review, we discuss preclinical and clinical findings showing dopaminergic mechanisms as key players in the cognitive improvement induced by both atypical antipsychotics and potential antipsychotics. We also emphasize the concept that these mechanistic advances, which help to understand the heterogeneity of cognitive responses to antipsychotics, may properly guide treatment decisions and address the unmet medical need for the management of cognitive impairment associated with schizophrenia.

Amisulpride, aripiprazole, and olanzapine in patients with schizophrenia-spectrum disorders (BeSt InTro): a pragmatic, rater-blind, semi-randomised trial

BACKGROUND

Amisulpride, aripiprazole, and olanzapine are first-line atypical antipsychotics that have not previously been compared head-to-head in a pragmatic trial. We aimed to compare the efficacy and safety of these agents in a controlled trial.

METHODS

This pragmatic, rater-blind, randomised controlled trial was done in three academic centres of psychiatry in Norway, and one in Austria. Eligible patients were aged 18 years or older, met ICD-10 criteria for schizophrenia-spectrum disorders (F20-29), and had symptoms of active psychosis. Eligible patients were randomly assigned to receive oral amisulpride, aripiprazole, or olanzapine. Treatment allocation was open to patients and staff, and starting dose, treatment changes, and adjustments were left to the discretion of the treating physician. Computer-generated randomisation lists for each study centre were prepared by independent statisticians. Patients were followed up for 52 weeks after random assignment, during which assessments were done 8 times by researchers masked to treatment. The primary outcome was reduction of the Positive And Negative Syndrome Scale (PANSS) total score at 52 weeks, and primary analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01446328.

FINDINGS

Between Oct 20, 2011, and Dec 30, 2016, we assessed 359 patients for eligibility. 215 patients were excluded (107 did not meet inclusion criteria, 82 declined to participate, 26 other reasons). 144 patients (mean baseline PANSS total estimated score 78·4 [SD 1·4]) were randomly assigned 1:1:1 to receive amisulpride (44 patients), aripiprazole (48 patients) or olanzapine (52 patients). After 52 weeks, the patients allocated to amisulpride had a PANSS total score reduction of 32·7 points (SD 3·1) compared with 21·9 points reduction with aripiprazole (SD 3·9, p=0·027) and 23·3 points with olanzapine (2·9, p=0·025). We observed weight gain and increases of serum lipids and prolactin in all groups. 26 serious adverse events (SAEs) among 20 patients were registered (four [9%] of 44 patients allocated to amisulpride, ten [21%] of 48 patients allocated to aripiprazole, and six [12%] of 52 patients allocated to olanzapine), with no statistically significant differences between the study drugs. 17 (65%) of the 26 SAEs occurred during the use of the study drug, with readmission or protracted hospital admission accounting for 13 SAEs. One death by suicide, one unspecified death, and one life-threatening accident occurred during follow-up, after cessation of treatment.

INTERPRETATION

Amisulpride was more efficacious than aripiprazole or olanzapine for reducing the PANSS total scores in adults with schizophrenia-spectrum disorders. Side-effect differences among the groups were generally small. This study supports the notion that clinically relevant efficacy differences exist between antipsychotic drugs. Future research should aim to compare first-line antipsychotics directly in pragmatic clinical trials that reflect everyday clinical practice.

FUNDING

The Research Council of Norway, the Western Norway Regional Health Trust, and participating hospitals and universities.

Interclass GPCR heteromerization affects localization and trafficking

Membrane trafficking processes regulate G protein-coupled receptor (GPCR) activity. Although class A GPCRs are capable of activating G proteins in a monomeric form, they can also potentially assemble into functional GPCR heteromers. Here, we showed that the class A serotonin 5-HT2A receptors (5-HT2ARs) affected the localization and trafficking of class C metabotropic glutamate receptor 2 (mGluR2) through a mechanism that required their assembly as heteromers in mammalian cells. In the absence of agonists, 5-HT2AR was primarily localized within intracellular compartments, and coexpression of 5-HT2AR with mGluR2 increased the intracellular distribution of the otherwise plasma membrane-localized mGluR2. Agonists for either 5-HT2AR or mGluR2 differentially affected trafficking through Rab5-positive endosomes in cells expressing each component of the 5-HT2AR-mGluR2 heterocomplex alone, or together. In addition, overnight pharmacological 5-HT2AR blockade with clozapine, but not with M100907, decreased mGluR2 density through a mechanism that involved heteromerization between 5-HT2AR and mGluR2. Using TAT-tagged peptides and chimeric constructs that are unable to form the interclass 5-HT2AR-mGluR2 complex, we demonstrated that heteromerization was necessary for the 5-HT2AR-dependent effects on mGluR2 subcellular distribution. The expression of 5-HT2AR also augmented intracellular localization of mGluR2 in mouse frontal cortex pyramidal neurons. Together, our data suggest that GPCR heteromerization may itself represent a mechanism of receptor trafficking and sorting.

Uric acid levels in subjects with schizophrenia: A systematic review and meta-analysis

The association between schizophrenia (SZ) and uric acid (UA) levels has been suggested for many years, but without solid evidence. Therefore, we conducted a systematic review and meta-analysis of all case-control studies examining the serum and plasma UA levels in SZ subjects in comparison to those in healthy controls. Relevant studies published before October 29, 2018, were searched in the main electronic databases, and 17 studies were finally included into the meta-analysis after screening with the criteria. Our results revealed that there were no statistically significant differences of the UA levels between SZ subjects and healthy controls. Further subgroup analyses of the antipsychotic status reported the same finding. Subgroup analyses of clinical status showed that UA levels were decreased in subjects with first episode psychosis (FEP). The subgroup analyses of gender and ethnicity demonstrated that UA levels were decreased in male subjects and in Americans with SZ. Overall, these findings strengthen the clinical evidence that FEP is accompanied by increased oxidative stress response. Reduced UA levels may be a potential risk factor for SZ in male and in the Americans. However, whether there is a causal relationship between the reduced UA levels and the development of SZ deserves further investigation.

The Schizophrenia Susceptibility Gene OPCML Regulates Spine Maturation and Cognitive Behaviors through Eph-Cofilin Signaling

Previous genetic and biological evidence converge on the involvement of synaptic dysfunction in schizophrenia, and OPCML, encoding a synaptic membrane protein, is reported to be genetically associated with schizophrenia. However, its role in the pathophysiology of schizophrenia remains largely unknown. Here, we found that Opcml is strongly expressed in the mouse hippocampus; ablation of Opcml leads to reduced phosphorylated cofilin and dysregulated F-actin dynamics, which disturbs the spine maturation. Furthermore, Opcml interacts with EphB2 to control the stability of spines by regulating the ephrin-EphB2-cofilin signaling pathway. Opcml-deficient mice display impaired cognitive behaviors and abnormal sensorimotor gating, which are similar to features in neuropsychiatric disorders such as schizophrenia. Notably, the administration of aripiprazole partially restores the abnormal behaviors in Opcml^-/- mice by increasing the phosphorylated cofilin level and facilitating spine maturation. We demonstrated a critical role of the schizophrenia-susceptible gene OPCML in spine maturation and cognitive behaviors via regulating the ephrin-EphB2-cofilin signaling pathway, providing further insights into the characteristics of schizophrenia.

Advances in the Discovery of PDE10A Inhibitors for CNS-Related Disorders. Part 2: Focus on Schizophrenia

Schizophrenia is a debilitating mental disorder with relatively high prevalence (~1%), during which positive manifestations (such as psychotic states) and negative symptoms (e.g., a withdrawal from social life) occur. Moreover, some researchers consider cognitive impairment as a distinct domain of schizophrenia symptoms. The imbalance in dopamine activity, namely an excessive release of this neurotransmitter in the striatum and insufficient amounts in the prefrontal cortex is believed to be partially responsible for the occurrence of these groups of manifestations. Second-generation antipsychotics are currently the standard treatment of schizophrenia. Nevertheless, the existent treatment is sometimes ineffective and burdened with severe adverse effects, such as extrapyramidal symptoms. Thus, there is an urgent need to search for alternative treatment options of this disease. This review summarizes the results of recent preclinical and clinical studies on phosphodiesterase 10A (PDE10A), which is highly expressed in the mammalian striatum, as a potential drug target for the treatment of schizophrenia. Based on the literature data, not only selective PDE10A inhibitors but also dual PDE2A/10A, and PDE4B/10A inhibitors, as well as multifunctional ligands with a PDE10A inhibitory potency are compounds that may combine antipsychotic, precognitive, and antidepressant functions. Thus, designing such compounds may constitute a new direction of research for new potential medications for schizophrenia. Despite failures of previous clinical trials of selective PDE10A inhibitors for the treatment of schizophrenia, new compounds with this mechanism of action are currently investigated clinically, thus, the search for new inhibitors of PDE10A, both selective and multitarget, is still warranted.

Polysialylation and disease

Polysialic acid (polySia, PSA) is a unique constituent of the glycocalyx on the surface of bacterial and vertebrate cells. In vertebrates, its biosynthesis is highly regulated, not only in quantity and quality, but also in time and location, which allows polySia to be involved in various important biological phenomena. Therefore, impairments in the expression and structure of polySia sometimes relate to diseases, such as schizophrenia, bipolar disorder, and cancer. Some bacteria express polySia as a tool for protecting themselves from the host immune system during invasion. PolySia is proven to be a biosafe material; polySia, as well as polySia-recognizing molecules, are key therapeutic agents. This review first comprehensive outlines the occurrence, features, biosynthesis, and functions of polySia and subsequently focuses on the related diseases.

The Role of Zebrafish and Laboratory Rodents in Schizophrenia Research

Schizophrenia is a severe disorder characterized by positive, negative and cognitive symptoms, which are still not fully understood. The development of efficient antipsychotics requires animal models of a strong validity, therefore the aims of the article were to summarize the construct, face and predictive validity of schizophrenia models based on rodents and zebrafish, to compare the advantages and disadvantages of these models, and to propose future directions in schizophrenia modeling and indicate when it is reasonable to combine these models. The advantages of rodent models stem primarily from the high homology between rodent and human physiology, neurochemistry, brain morphology and circuitry. The advantages of zebrafish models stem in the high fecundity, fast development and transparency of the embryo. Disadvantages of both models originate in behavioral repertoires not allowing specific symptoms to be modeled, even when the models are combined. Especially modeling the verbal component of certain positive, negative and cognitive symptoms is currently impossible.

Chlorpromazine eliminates acute myeloid leukemia cells by perturbing subcellular localization of FLT3-ITD and KIT-D816V

Mutated receptor tyrosine kinases (MT-RTKs) such as internal tandem duplication of FMS-like tyrosine kinase 3 (FLT3 ITD) and a point mutation KIT D816V are driver mutations for acute myeloid leukemia (AML). Clathrin assembly lymphoid myeloid leukemia protein (CALM) regulates intracellular transport of RTKs, however, the precise role for MT-RTKs remains elusive. We here show that CALM knock down leads to severely impaired FLT3 ITD- or KIT D814V-dependent cell growth compared to marginal influence on wild-type FLT3- or KIT-mediated cell growth. An antipsychotic drug chlorpromazine (CPZ) suppresses the growth of primary AML samples, and human CD34+CD38- AML cells including AML initiating cells with MT-RTKs in vitro and in vivo. Mechanistically, CPZ reduces CALM protein at post transcriptional level and perturbs the intracellular localization of MT-RTKs, thereby blocking their signaling. Our study presents a therapeutic strategy for AML with MT-RTKs by altering the intracellular localization of MT-RTKs using CPZ.

Gestational Factors throughout Fetal Neurodevelopment: The Serotonin Link

Serotonin (5-HT) is a critical player in brain development and neuropsychiatric disorders. Fetal 5-HT levels can be influenced by several gestational factors, such as maternal genotype, diet, stress, medication, and immune activation. In this review, addressing both human and animal studies, we discuss how these gestational factors affect placental and fetal brain 5-HT levels, leading to changes in brain structure and function and behavior. We conclude that gestational factors are able to interact and thereby amplify or counteract each other's impact on the fetal 5-HT-ergic system. We, therefore, argue that beyond the understanding of how single gestational factors affect 5-HT-ergic brain development and behavior in offspring, it is critical to elucidate the consequences of interacting factors. Moreover, we describe how each gestational factor is able to alter the 5-HT-ergic influence on the thalamocortical- and prefrontal-limbic circuitry and the hypothalamo-pituitary-adrenocortical-axis. These alterations have been associated with risks to develop attention deficit hyperactivity disorder, autism spectrum disorders, depression, and/or anxiety. Consequently, the manipulation of gestational factors may be used to combat pregnancy-related risks for neuropsychiatric disorders.

Controlled sleep deprivation as an experimental medicine model of schizophrenia: An update

In recent years there has been a surge of interest and corresponding accumulation of knowledge about the role of sleep disturbance in schizophrenia. In this review, we provide an update on the current status of experimentally controlled sleep deprivation (SD) as an experimental medicine model of psychosis, and also consider, given the complexity and heterogeneity of schizophrenia, whether this (state) model can be usefully combined with other state or trait model systems to more powerfully model the pathophysiology of psychosis. We present evidence of dose-dependent aberrations that qualitatively resemble positive, negative and cognitive symptoms of schizophrenia as well as deficits in a range of translational biomarkers for schizophrenia, including prepulse inhibition, smooth pursuit and antisaccades, following experimentally controlled SD, relative to standard sleep, in healthy volunteers. Studies examining the combination of SD and schizotypy, a trait model of schizophrenia, revealed only occasional, task-dependent superiority of the combination model, relative to either of the two models alone. Overall, we argue that experimentally controlled SD is a valuable experimental medicine model of schizophrenia to advance our understanding of the pathophysiology of the clinical disorder and discovery of more effective or novel treatments. Future studies are needed to test its utility in combination with other, especially state, model systems of psychosis such as ketamine.

Successful rechallenge with paliperidone after clozapine treatment for a patient with dopamine supersensitivity psychosis

We describe the case of a 49-year-old Japanese male patient successfully treated with a paliperidone rechallenge following 2-year treatment with clozapine for treatment-resistant schizophrenia. He had responded well to conventional antipsychotic treatment for the initial psychotic episode but gradually developed dopamine supersensitivity; even treatment with paliperidone and another antipsychotic medication (a total up to 1700 mg in chlorpromazine-equivalent dose) had not improved his psychotic symptoms. Clozapine treatment produced temporary symptomatic relief, but the clozapine dose could not be increased to > 150 mg due to the patient’s intolerance. Following low-dose clozapine treatment for 2 years, a rechallenge with paliperidone monotherapy ameliorated his psychotic symptoms. This suggests that clozapine may have the potential to release the dopamine supersensitivity state. Our patient’s case indicates that for patients with dopamine supersensitivity psychosis, a rechallenge with a previously ineffective antipsychotic after clozapine treatment may be successful.

A medicinal chemistry perspective of drug repositioning: Recent advances and challenges in drug discovery

Drug repurposing is a strategy consisting of finding new indications for already known marketed drugs used in various clinical settings or highly characterized compounds despite they can be failed drugs. Recently, it emerges as an alternative approach for the rapid identification and development of new pharmaceuticals for various rare and complex diseases for which lack the effective drug treatments. The success rate of drugs repurposing approach accounts for approximately 30% of new FDA approved drugs and vaccines in recent years. This review focuses on the status of drugs repurposing approach for various diseases including skin diseases, infective, inflammatory, cancer, and neurodegenerative diseases. Efforts have been made to provide structural features and mode of actions of drugs.

Glutamatergic neurometabolites and cortical thickness in treatment-resistant schizophrenia: Implications for glutamate-mediated excitotoxicity

Treatment-resistant schizophrenia may be related to structural brain alterations. However, the mechanisms underlying these changes remain unclear. The present study had two main aims: (1) to explore differences in cortical thickness between patients with treatment-resistant schizophrenia non-responsive to clozapine (ultra-treatment-resistant schizophrenia, UTRS), patients with treatment-resistant schizophrenia responsive to clozapine (Cloz-Resp), patients responsive to first-line non-clozapine antipsychotics (FL-Resp), and healthy controls (HCs); and (2) to test our hypothesis of structural compromise as a manifestation of neurotoxic effects from elevated glutamate (Glu) (i.e. glutamate-mediated excitotoxicity) by examining the relationships between glutamatergic neurometabolite levels (Glu and glutamate + glutamine (Glx)) in the dorsal anterior cingulate cortex (dACC) and cortical thickness. T1-weighted images and ¹H-MRS data were obtained from UTRS (n = 24), Cloz-Resp (n = 25), FL-Resp (n = 19), and HCs (n = 26). Vertex-wise analyses showed that patients with UTRS had widespread cortical thinning in the bilateral frontal, temporal, parietal, and occipital gyri compared to HCs and FL-Resp patients. In the patient group, negative associations were found between dACC Glx levels and cortical thickness in the right dorsolateral prefrontal cortex after correcting for multiple comparisons and controlling for age, sex, antipsychotic dose, and illness severity. In conclusion, glutamate-mediated excitotoxicity may be one of the mechanisms underlying structural compromise seen in treatment-resistant schizophrenia. Future studies should longitudinally examine the associations between glutamatergic neurometabolite levels and cortical thickness in the context of treatment and illness progression.

Zebrafish as a tool to study schizophrenia-associated copy number variants

Schizophrenia remains one of the most debilitating human neurodevelopmental disorders, with few effective treatments and striking consequences felt by individuals, communities and society as a whole. As such, there remains a critical need for further investigation into the mechanistic underpinnings of schizophrenia so that novel therapeutic targets can be identified. Because schizophrenia is a highly heritable disorder, genetic risk factors remain an attractive avenue for this research. Given their clear molecular genetic consequences, recurrent microdeletions and duplications, or copy number variants (CNVs), represent one of the most tractable genetic entry points to elucidating these mechanisms. To date, eight CNVs have been shown to significantly increase the risk of schizophrenia. Although rodent models of these CNVs that exhibit behavioral phenotypes have been generated, the underlying molecular mechanisms remain largely elusive. Over the past decades, the zebrafish has emerged as a powerful vertebrate model that has led to fundamental discoveries in developmental neurobiology and behavioral genetics. Here, we review the attributes that make zebrafish exceptionally well suited to investigating individual and combinatorial gene contributions to CNV-mediated brain dysfunction in schizophrenia. With highly conserved genetics and neural substrates, an ever-expanding molecular genetic and imaging toolkit, and ability to perform high-throughput and high-content genetic and pharmacologic screens, zebrafish is poised to generate deep insights into the molecular genetic mechanisms of schizophrenia-associated neurodevelopmental and behavioral deficits, and to facilitate the identification of therapeutic targets.

Phosphodiesterase 10A Inhibitor Monotherapy Is Not an Effective Treatment of Acute Schizophrenia

BACKGROUND

Current treatments for psychotic symptoms associated with schizophrenia often provide inadequate efficacy with unacceptable adverse effects. Improved therapeutics have long been a goal of research. Preclinical testing suggests that phosphodiesterase 10A (PDE10A) inhibitors may provide a novel approach to treating psychosis associated with schizophrenia.

METHODS

The efficacy and safety of a highly selective PDE10A inhibitor, PF-02545920, was evaluated in a phase 2 multicenter, randomized, double-blind, placebo-controlled, parallel-group study. Eligible patients (18-65 years) with an acute exacerbation of schizophrenia were randomized 2:2:1:2 to PF-02545920 (5 or 15 mg every 12 hours [Q12H] titrated), risperidone (3 mg Q12H), or placebo for 28 days (n = 74:74:37:74). The primary objectives were to evaluate the efficacy of PF-02545920 using the Positive and Negative Syndrome Scale (PANNS) and safety/tolerability.

RESULTS

At day 28, PF-02545920 (either dose) was not significantly different from placebo for mean change from baseline in the PANNS total score (primary end point) or most other end points. Pharmacokinetics exposures seemed adequate for binding/inhibiting PDE10A enzyme. Risperidone was statistically different from placebo for the PANNS total score, demonstrating study sensitivity. Incidence rates for adverse events were similar among the groups. Both doses of PF-02545920 were generally well tolerated. Dystonia occurred in 1, 6, 0, and 3 patients in the PF-02545920 5 mg Q12H, PF-02545920 15 mg Q12H, risperidone, and placebo groups, respectively.

CONCLUSIONS

Neither dose of PF-02545920 was superior to placebo for the primary and most secondary end points. This indicates that PDE10A inhibition does not produce an antipsychotic effect in patients with acute exacerbation of schizophrenia.

Recent discovery and development of inhibitors targeting coronaviruses

Human coronaviruses (CoVs) are enveloped viruses with a positive-sense single-stranded RNA genome. Currently, six human CoVs have been reported including human coronavirus 229E (HCoV-229E), OC43 (HCoV-OC43), NL63 (HCoV-NL63), HKU1 (HCoV-HKU1), severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV), and MiddleEast respiratory syndrome (MERS) coronavirus (MERS-CoV). They cause moderate to severe respiratory and intestinal infections in humans. In this review, we focus on recent advances in the research and development of small-molecule anti-human coronavirus therapies targeting different stages of the CoV life cycle.

A comparative, single-blind, randomized study on quetiapine and aripiperazole augmentation in treatment of selective serotonin reuptake inhibitor refractory obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a chronic psychiatric disorder, of unknown etiology, that affects 2.5% of the population. An appropriate therapeutic response to conventional treatment is seen. Some studies use augmentative treatment by antipsychotics, glutamatergic, lithium, buspirone, and others agents to improve the therapeutic response. In this study, we aimed to evaluate the efficacy and tolerability of aripiprazole and quetiapine as augmentative treatments in patients with selective serotonin reuptake inhibitor (SSRI) refractory OCD. The OCD patients were initially treated for 12 weeks with a SSRI. If after 12 weeks their Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score was more than 16, they were randomly assigned to either the aripiprazole or the quetiapine augmentation group for an additional 12 weeks. There were no significant differences in age, sex, education, marital status, or score of Y-BOCS and Clinical Global Impression-Severity Scale (CGI-S) between groups (p > 0.05) at the outset of the study. Significant differences were noted after 1 month when compared with results at 2, 3, and 4 months in both groups (p < 0.001). Both quetiapine and aripiprazole may be effective and well-tolerated augmentative agents in the treatment of SSRI-refractory OCD. Because of positive results, aripiprazole may be considered more effective and may have a more rapid onset in terms of therapeutic response.

The novel antipsychotic cariprazine stabilizes gamma oscillations in rat hippocampal slices

Background and Purpose

Gamma oscillations are fast rhythmic fluctuations of neuronal network activity ranging from 30 to 90 Hz that establish a precise temporal background for cognitive processes such as perception, sensory processing, learning, and memory. Alterations of gamma oscillations have been observed in schizophrenia and are suggested to play crucial roles in the generation of positive, negative, and cognitive symptoms of the disease.

Experimental Approach

In this study, we investigated the effects of the novel antipsychotic cariprazine, a D₃‐preferring dopamine D₃/D₂ receptor partial agonist, on cholinergically induced gamma oscillations in rat hippocampal slices from treatment‐naïve and MK‐801‐treated rats, a model of acute first‐episode schizophrenia.

Key Results

The D₃ receptor‐preferring agonist pramipexole effectively decreased the power of gamma oscillations, while the D₃ receptor antagonist SB‐277011 had no effect. In treatment‐naïve animals, cariprazine did not modulate strong gamma oscillations but slightly improved the periodicity of non‐saturated gamma activity. Cariprazine showed a clear partial agonistic profile at D₃ receptors at the network level by potentiating the inhibitory effects when the D₃ receptor tone was low and antagonizing the effects when the tone was high. In hippocampal slices of MK‐801‐treated rats, cariprazine allowed stabilization of the aberrant increase in gamma oscillation power and potentiated resynchronization of the oscillations.

Conclusion and Implications

Data from this study indicate that cariprazine stabilizes pathological hippocampal gamma oscillations, presumably by its partial agonistic profile. The results demonstrate in vitro gamma oscillations as predictive biomarkers to study the effects of antipsychotics preclinically at the network level.

Fluorescent ligands: Bringing light to emerging GPCR paradigms

In recent years, several novel aspects of GPCR pharmacology have been described, which are thought to play a role in determining the in vivo efficacy of a compound. Fluorescent ligands have been used to study many of these, which have also required the development of new experimental approaches. Fluorescent ligands offer the potential to use the same fluorescent probe to perform a broad range of experiments, from single-molecule microscopy to in vivo BRET. This review provides an overview of the in vitro use of fluorescent ligands in further understanding emerging pharmacological paradigms within the GPCR field, including ligand-binding kinetics, allosterism and intracellular signalling, along with the use of fluorescent ligands to study physiologically relevant therapeutic agents.

ASP2905, a specific inhibitor of the potassium channel Kv12.2 encoded by the Kcnh3 gene, is psychoactive in mice

Schizophrenia is a major psychiatric disorder associated with positive and negative symptoms and cognitive impairments. In this study, we used animal models of behavior to evaluate the antipsychotic activity of ASP2905, a potent and selective inhibitor of the potassium channel Kv12.2 encoded by the Kcnh3/BEC1 gene. ASP2905 inhibited hyperlocomotion induced by methamphetamine and by phencyclidine. In contrast, ASP2905 did not affect spontaneous locomotion, suggesting that ASP2905 selectively inhibits abnormal behaviors induced by stimulants. Chronic infusion of ASP2905 significantly ameliorated phencyclidine-induced prolongation of immobility time in mice subjected to the forced swimming test. These findings suggest that ASP2905 potentially mitigates symptoms of schizophrenia, such as apathy. The antipsychotic clozapine also reversed phencyclidine-induced prolonged immobility, while risperidone and haloperidol had no effect. Assessment of the effects of ASP2905 on latent learning deficits in mice treated with phencyclidine as neonates subjected to the water-finding task showed that ASP2905 significantly ameliorated phencyclidine-induced prolongation of finding latency, which reflects latent learning performance. These findings suggest that ASP2905 potentially mitigates cognitive impairments caused by schizophrenia, such as attention deficits. In contrast, administration of clozapine did not ameliorate phencyclidine-induced prolongation of finding latency. Therefore, ASP2905 may alleviate the broad spectrum of symptoms of schizophrenia, including positive and negative symptoms and cognitive impairments, which is in contrast to currently available antipsychotics, which are generally only partially effective for ameliorating these symptoms.

Medication Profile and Treatment Cost Estimation Among Outpatients with Schizophrenia, Bipolar Disorder, Depression, and Anxiety Disorders in Indonesia

PURPOSE

The present retrospective study aimed to determine the medication profile and estimate the treatment costs from medical records of new outpatients with schizophrenia, bipolar disorder, depression, and anxiety disorders from a healthcare perspective at a national referral hospital in Indonesia from 2016 to 2018.

METHODS

Medical records (including medical and administrative data) of 357 new outpatients with schizophrenia, bipolar disorder, depression, or anxiety disorders were collected from the hospital information system. The records of new outpatients with schizophrenia, bipolar disorder, depression, or anxiety disorders aged >18 years and had only received drugs for treatment were included. The medication profile was descriptively assessed, and estimated costs were calculated based on direct costs from a healthcare perspective.

RESULTS

Overall, 173 medical records were further analyzed. The main drugs administered to the new outpatients were atypical and typical antipsychotics for schizophrenia, atypical antipsychotics and mood stabilizers for bipolar disorder, antidepressants and atypical antipsychotics for depression, and antidepressants and benzodiazepines for anxiety disorders. The average annual treatment costs per patient were IDR 3,307,931 (USD 236) for schizophrenia, IDR 17,978,865 (USD 1,284) for bipolar disorder, IDR 1,601,850 (USD 114) for depression, and IDR 1,190,563 (USD 85) for anxiety disorders.

CONCLUSION

The most commonly prescribed drugs for schizophrenia were haloperidol and risperidone; for bipolar disorders, sodium divalproex and risperidone; for depression, fluoxetine and sertraline; and for anxiety disorders, sertraline and lorazepam. Considering the high prevalence and estimated treatment costs for mental disorders, special attention is required to prevent an increase in their prevalence in Indonesia.

The Role of Adiponectin in the Pathogenesis of Metabolic Disturbances in Patients With Schizophrenia

Antipsychotic-induced metabolic disturbance is a common adverse event occurring in patients treated with antipsychotic drugs. The mechanisms underlying metabolic dysregulation are complex, involving various neurochemical and hormonal systems, the interaction of genetic and lifestyle risk factors, and the antipsychotic drug prescribed. Recently, there has been increasing interest in the relationship between antipsychotic-induced metabolic disturbances and body weight regulatory hormones such as adiponectin. Adiponectin, an adipocyte-derived protein related to insulin sensitivity, weight gain, and anti-inflammation, has attracted great attention because of its potential role of being a biomarker to predict cardiovascular and metabolic diseases. Previous studies regarding the effects of antipsychotics on blood adiponectin levels have shown controversial results. Several factors might contribute to those inconsistent results, including different antipsychotic drugs, duration of antipsychotic exposure, age, sex, and ethnicity. Here we summarize the existing evidence on the link between blood adiponectin levels and metabolic disturbances related to antipsychotic drugs in patients with schizophrenia. We further discuss the effects of individual antipsychotics, patients' gender, ethnicity, age, and treatment duration on those relationships. We propose that olanzapine and clozapine might have a time-dependent biphasic effect on blood adiponectin levels in patients with schizophrenia.

Serotonin 5-HT2A receptor expression and functionality in postmortem frontal cortex of subjects with schizophrenia: Selective biased agonism via Gαi1-proteins

Serotonin 5-HT_2A receptors (5-HT_2ARs) have been implicated in schizophrenia. However, postmortem studies on 5-HT_2ARs expression and functionality in schizophrenia are scarce. The 5-HT_2AR mRNA and immunoreactive protein expression were evaluated in postmortem tissue from dorsolateral prefrontal cortex (DLPFC) of antipsychotic-free (n = 18) and antipsychotic-treated (n = 9) subjects with schizophrenia, and matched controls (n = 27). Functional coupling of 5-HT_2AR to G-proteins was tested by measuring the activation induced by the agonist (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride ((±)DOI) in antibody-capture [³⁵S]GTPγS scintillation proximity assays (SPA). In antipsychotic-free schizophrenia subjects, 5-HT_2AR mRNA expression and protein immunoreactivity in total homogenates was similar to controls. In contrast, in antipsychotic-treated schizophrenia subjects, lower mRNA expression (60±9% vs controls) and a trend to reduced protein immunoreactivity (86±5% vs antipsychotic-free subjects) just in membrane-enriched fractions was observed. [³⁵S]GTPγS SPA revealed a significant ~6% higher stimulation of G_αi1-protein by (±)DOI in schizophrenia, whereas activation of the canonical G_αq/11-protein pathway by (±)DOI remained unchanged. Expression of G_αi1- and G_αq/11-proteins did not differ between groups. Accordingly, in rats chronically treated with clozapine, but not with haloperidol, a 30-40% reduction was observed in 5-HT_2AR mRNA expression, 5-HT_2AR protein immunoreactivity and [³H]ketanserin binding in brain cortical membranes. Overall, the data suggest a supersensitive 5-HT_2AR signaling through inhibitory G_αi1-proteins in schizophrenia. Together with previous results, a dysfunctional pro-hallucinogenic agonist-sensitive 5-HT_2AR conformation in postmortem DLPFC of subjects with schizophrenia is proposed. Atypical antipsychotic treatment would contribute to counterbalance this 5-HT_2AR supersensitivity by reducing receptor expression.

Neuropeptides and oligopeptidases in schizophrenia

Schizophrenia (SCZ) is a complex psychiatric disorder with severe impact on patient's livelihood. In the last years, the importance of neuropeptides in SCZ and other CNS disorders has been recognized, mainly due to their ability to modulate the signaling of classical monoaminergic neurotransmitters as dopamine. In addition, a class of enzymes coined as oligopeptidases are able to cleave several of these neuropeptides, and their potential implication in SCZ was also demonstrated. Interestingly, these enzymes are able to play roles as modulators of neuropeptidergic systems, and they were also implicated in neurogenesis, neurite outgrowth, neuron migration, and therefore, in neurodevelopment and brain formation. Altered activity of oligopeptidases in SCZ was described only more recently, suggesting their possible utility as biomarkers for mental disorders diagnosis or treatment response. We provide here an updated and comprehensive review on neuropeptides and oligopeptidases involved in mental disorders, aiming to attract the attention of physicians to the potential of targeting this system for improving the therapy and for understanding the neurobiology underlying mental disorders as SCZ.

Clozapine augmentation strategies

Clozapine is established as the gold standard for antipsychotic treatment of patients suffering from treatment-resistant schizophrenia. Over virtually 3 decades, the level of inadequate response to clozapine was found to range from 40% to 60%. A heightened interest developed in the augmentation of clozapine to try to achieve response or maximize partial response. A large variety of drug groups have been investigated. This article focuses on the meta-analyses of these trials to discover reasonable evidence-based approaches to the management of patients not responding to clozapine.

Structure-Kinetic Profiling of Haloperidol Analogues at the Human Dopamine D2 Receptor

Haloperidol is a typical antipsychotic drug (APD) associated with an increased risk of extrapyramidal side effects (EPSs) and hyperprolactinemia relative to atypical APDs such as clozapine. Both drugs are dopamine D₂ receptor (D₂R) antagonists, with contrasting kinetic profiles. Haloperidol displays fast association/slow dissociation at the D₂R, whereas clozapine exhibits relatively slow association/fast dissociation. Recently, we have provided evidence that slow dissociation from the D₂R predicts hyperprolactinemia, whereas fast association predicts EPS. Unfortunately, clozapine can cause severe side effects independent of its D₂R action. Our results suggest an optimal kinetic profile for D₂R antagonist APDs that avoids EPS. To begin exploring this hypothesis, we conducted a structure-kinetic relationship study of haloperidol and revealed that subtle structural modifications dramatically change binding kinetic rate constants, affording compounds with a clozapine-like kinetic profile. Thus, optimization of these kinetic parameters may allow development of novel APDs based on the haloperidol scaffold with improved side-effect profiles.

A botanical drug composed of three herbal materials attenuates the sensorimotor gating deficit and cognitive impairment induced by MK-801 in mice

Objectives

A botanical drug derived from the ethanolic extract composed of Clematis chinensis Osbeck (Ranunculaceae), Trichosanthes kirilowii Maximowicz (Cucurbitaceae) and Prunella vulgaris Linné (Lamiaceae) has been used to ameliorate rheumatoid arthritis as an ethical drug in Korea. In our study, we investigated the effect of this herbal complex extract (HCE) on schizophrenia-like behaviours induced by MK-801.

Methods

HCE (30, 100 or 300 mg/kg, p.o) was orally administered to male ICR mice to a schizophrenia-like animal model induced by MK-801. We conducted an acoustic startle response task, an open-field task, a novel object recognition task and a social novelty preference task.

Key findings

We found that a single administration of HCE (100 or 300 mg/kg) ameliorated MK-801-induced abnormal behaviours including sensorimotor gating deficits and social or object recognition memory deficits. In addition, MK-801-induced increases in phosphorylated Akt and GSK-3β expression levels in the prefrontal cortex were reversed by HCE (30, 100 or 300 mg/kg).

Conclusions

These results imply that HCE ameliorates MK-801-induced dysfunctions in prepulse inhibition, social interactions and cognitive function, partly by regulating the Akt and GSK-3β signalling pathways.

Kynurenines and the Endocannabinoid System in Schizophrenia: Common Points and Potential Interactions

Schizophrenia, which affects around 1% of the world’s population, has been described as a complex set of symptoms triggered by multiple factors. However, the exact background mechanisms remain to be explored, whereas therapeutic agents with excellent effectivity and safety profiles have yet to be developed. Kynurenines and the endocannabinoid system (ECS) play significant roles in both the development and manifestation of schizophrenia, which have been extensively studied and reviewed previously. Accordingly, kynurenines and the ECS share multiple features and mechanisms in schizophrenia, which have yet to be reviewed. Thus, the present study focuses on the main common points and potential interactions between kynurenines and the ECS in schizophrenia, which include (i) the regulation of glutamatergic/dopaminergic/γ-aminobutyric acidergic neurotransmission, (ii) their presence in astrocytes, and (iii) their role in inflammatory mechanisms. Additionally, promising pharmaceutical approaches involving the kynurenine pathway and the ECS will be reviewed herein.

Systematic review and exploratory meta-analysis of the efficacy, safety, and biological effects of psychostimulants and atomoxetine in patients with schizophrenia or schizoaffective disorder

OBJECTIVE

Our aim was to summarize the efficacy and safety of atomoxetine, amphetamines, and methylphenidate in schizophrenia.

METHODS

We undertook a systematic review, searching PubMed/Scopus/Clinicaltrials.gov for double-blind, randomized, placebo-controlled studies of psychostimulants or atomoxetine in schizophrenia published up to 1 January 2017. A meta-analysis of outcomes reported in two or more studies is presented.

RESULTS

We included 22 studies investigating therapeutic effects of stimulants (k=14) or measuring symptomatic worsening/relapse prediction after stimulant challenge (k=6). Six studies of these two groups plus one additional study investigated biological effects of psychostimulants or atomoxetine. No effect resulted from interventional studies on weight loss (k=1), smoking cessation (k=1), and positive symptoms (k=12), and no improvement was reported with atomoxetine (k=3) for negative symptoms, with equivocal findings for negative (k=6) and mood symptoms (k=2) with amphetamines. Attention, processing speed, working memory, problem solving, and executive functions, among others, showed from no to some improvement with atomoxetine (k=3) or amphetamines (k=6). Meta-analysis did not confirm any effect of stimulants in any symptom domain, including negative symptoms, apart from atomoxetine improving problem solving (k=2, standardized mean difference (SMD)=0.73, 95% CI=0.10-1.36, p=0.02, I2=0%), and trending toward significant improvement in executive functions with amphetamines (k=2, SMD=0.80, 95% CI=-1.68 to +0.08, p=0.08, I2=66%). In challenge studies, amphetamines (k=1) did not worsen symptoms, and methylphenidate (k=5) consistently worsened or predicted relapse. Biological effects of atomoxetine (k=1) and amphetamines (k=1) were cortical activation, without change in β-endorphin (k=1), improved response to antipsychotics after amphetamine challenge (k=2), and an increase of growth hormone-mediated psychosis with methylphenidate (k=2). No major side effects were reported (k=6).

CONCLUSIONS

No efficacy for stimulants or atomoxetine on negative symptoms is proven. Atomoxetine or amphetamines may improve cognitive symptoms, while methylphenidate should be avoided in patients with schizophrenia. Insufficient evidence is available to draw firm conclusions.

Adjunctive use of anti-inflammatory drugs for schizophrenia: A meta-analytic investigation of randomized controlled trials

OBJECTIVE

Recent evidence suggests that adjuvant anti-inflammatory agents could improve the symptoms of patients with schizophrenia. However, the effects of the adjuvant anti-inflammatory agents on cognitive function, general functioning and side effects have not yet been systematically investigated. The present meta-analysis aimed to explore the effects of anti-inflammatory agents in patients with schizophrenia comprehensively.

METHOD

We performed a literature search in online databases, including PubMed, EMBASE and the Cochrane Database of Systematic Reviews. Randomized, placebo-controlled double-blind studies that investigated clinical outcomes including psychopathology, neurocognition, general functioning and extrapyramidal side effects were included. The examined anti-inflammatory agents included aspirin, celecoxib, omega-3 fatty acids, estrogen, selective estrogen receptor modulator, pregnenolone, N-acetylcysteine, minocycline, davunetide and erythropoietin.

RESULTS

Sixty-two double-blind randomized clinical trials studying 2914 patients with schizophrenia met the inclusion criteria for quantitative analysis. Significant overall effects were found for anti-inflammatory agents for reducing total, positive and negative symptom scores in the Positive and Negative Syndrome Scale. Cognitive improvements were significant with minocycline and pregnenolone augmentation therapy. General functioning was significantly enhanced by overall anti-inflammatory agents. There were no significant differences in side effects compared with placebo. Baseline total Positive and Negative Syndrome Scale score and illness duration were identified as moderating factors in the effects of anti-inflammatory augmentation on psychiatric symptom improvements.

CONCLUSION

The comparative evaluation of efficacy and safety supported the use of anti-inflammatory adjuvant therapy over the use of antipsychotics alone. However, future studies could focus on patients with homogeneous clinical profile to figure out more detailed effects of anti-inflammatory therapy.

Clozapine-dependent inhibition of EGF/neuregulin receptor (ErbB) kinases

Clozapine is an antipsychotic agent prescribed to psychotic patients exhibiting tolerance and/or resistance to the conventional antipsychotic medications that mainly drive monoamine antagonism. As the pharmacological fundamentals of its unique antipsychotic profile have been unrevealed, here, we attempted to obtain hints at this question. Here, we found that clozapine directly acts on ErbB kinases to downregulate epidermal growth factor (EGF)/neuregulin signaling. In cultured cell lines and cortical neurons, EGF-triggered ErbB1 phosphorylation was diminished by 30 μM clozapine, but not haloperidol, risperidone, or olanzapine. The neuregulin-1-triggered ErbB4 phosphorylation was attenuated by 10 μM clozapine and 30 μM haloperidol. We assumed that clozapine may directly interact with the ErbB tyrosine kinases and affect their enzyme activity. To test this assumption, we performed in vitro kinase assays using recombinant truncated ErbB kinases. Clozapine (3-30 μM) significantly decreased the enzyme activity of the truncated ErbB1, B2, and B4 kinases. Acute in vivo administration of clozapine (20 mg/kg) to adult rats significantly suppressed the basal phosphorylation levels of ErbB4 in the brain, although we failed to detect effects on basal ErbB1 phosphorylation. Altogether with the previous findings that quinazoline inhibitors for ErbB kinases harbor antipsychotic potential in animal models for schizophrenia, our present observations suggest the possibility that the micromolar concentrations of clozapine can attenuate the activity of ErbB receptor kinases, which might illustrate a part of its unique antipsychotic psychopharmacology.

Using proton magnetic resonance spectroscopic imaging to study glutamatergic alterations in patients with schizophrenia: A systematic review

The glutamate hypothesis of schizophrenia posits aberrant glutamatergic activity in patients with schizophrenia. Levels of glutamate and glutamine can be detected and quantified in vivo by proton magnetic resonance spectroscopy. A related technique, proton magnetic resonance spectroscopic imaging (¹H-MRSI), is particularly useful as it simultaneously collects multiple spectra, across multiple voxels, from a single acquisition. The primary aim of this study was to review and discuss the use of ¹H-MRSI to measure levels of glutamate and glutamine in patients with schizophrenia. Additionally, the advantages and disadvantages of using ¹H-MRSI to examine schizophrenia pathophysiology are discussed. A literature search was conducted through Ovid. English language studies utilizing ¹H-MRSI to measure glutamate and glutamine in patients with schizophrenia were identified. Six studies met the inclusion criteria. The included studies provide inconclusive support for glutamatergic elevations within frontal brain regions in patients with schizophrenia. The key benefit of employing ¹H-MRSI to examine schizophrenia pathophysiology appears to be its broader spatial coverage. Future ¹H-MRSI studies utilizing large sample sizes and longitudinal study designs are necessitated to further our understanding of glutamatergic alterations in patients with schizophrenia.

Galantamine-Memantine Combination as an Antioxidant Treatment for Schizophrenia

PURPOSE OF REVIEW

The objective of this article is to highlight the potential role of the galantamine-memantine combination as a novel antioxidant treatment for schizophrenia.

RECENT FINDINGS

In addition to the well-known mechanisms of action of galantamine and memantine, these medications also have antioxidant activity. Furthermore, an interplay exists between oxidative stress, inflammation (redox-inflammatory hypothesis), and kynurenine pathway metabolites. Also, there is an interaction between brain-derived neurotrophic factor and oxidative stress in schizophrenia. Oxidative stress may be associated with positive, cognitive, and negative symptoms and impairments in white matter integrity in schizophrenia. The antipsychotic-galantamine-memantine combination may provide a novel strategy in schizophrenia to treat positive, cognitive, and negative symptoms.

SUMMARY

A "single antioxidant" may be inadequate to counteract the complex cascade of oxidative stress. The galantamine-memantine combination as "double antioxidants" is promising. Hence, randomized controlled trials are warranted with the antipsychotic-galantamine-memantine combination with oxidative stress and antioxidant biomarkers in schizophrenia.

Adjunctive ondansetron for schizophrenia: A systematic review and meta-analysis of randomized controlled trials

The serotonin 5-hydroxytryptamine type 3 (5-HT3) receptor has been implicated in the pathogenesis of schizophrenia. This meta-analysis of randomized controlled trials (RCTs) examined the efficacy and safety of adjunctive ondansetron, a potent 5-HT3 receptor antagonist, in the treatment of schizophrenia. Only RCTs examining adjunctive ondansetron for schizophrenia were included. Standardized mean difference (SMD), risk ratio (RR) and their 95% confidence intervals (CIs) were analyzed using RevMan, Version 5.3. Study quality was evaluated with the Cochrane risk of bias and the Jadad scale. Data of 5 RCTs (n = 304) covering 149 patients on ondansetron (4-8 mg/day) and 155 patients on placebo were analyzed. Three RCTs reported "randomized allocation" with a specific description; the weighted Jadad score was 3.8. Adjunctive ondansetron outperformed placebo in the reduction of Positive and Negative Syndrome Scale (PANSS) total score [3 RCTs, n = 171; SMD: -1.06 (95%CI: -2.10, -0.02), p = 0.04, I² = 85%], the negative [4 RCTs, n = 209; SMD: -0.96 (95%CI: -1.71, -0.22), p = 0.01, I² = 80%], and general psychopathology symptom scores [3 RCTs, n = 171; SMD: -0.97 (95%CI: -1.91, -0.02), p = 0.04, I² = 82%], but not in the positive (p = 0.05) and depressive symptom scores (p = 0.91). The difference in PANSS total score remained significant after excluding one outlying RCT [2 RCTs, n = 141; SMD: -0.50 (95%CI: -0.84, -0.16), P = 0.004, I² = 0%]. Four RCTs examined the effect of ondansetron on cognition applying different instruments yielding conflicting findings. Ondansetron was superior over placebo in improving extrapyramidal symptoms, but no group differences were found in overall discontinuation rate and adverse drug reactions. In conclusion, adjunctive ondansetron appears to be efficacious and safe in improving negative symptoms and general psychopathology. The effect of ondansetron on cognitive impairment in schizophrenia needs to be further explored in large-scale RCTs.

Metformin reverses the schizophrenia-like behaviors induced by MK-801 in rats

Schizophrenia is known to be a complex and disabling psychiatric disorder. Dopamine receptor antagonists have a significant therapeutic effect in improving the positive symptoms that are associated with the illness. Therefore, dopamine receptor antagonists are commonly used in the treatment of schizophrenia; however, they do not achieve satisfactory results in improving negative symptoms and cognitive impairment. Metformin, widely known as an antidiabetic drug, has been found to enhance spatial memory formation and improve anxiety-like behaviors in rodents. Metformin's neuroprotective effect has been well documented in several neurological disorders including Alzheimer's disease, Parkinson's disease, strokes, Huntington's disease, and seizures. In the present study, we used a rat model to explore the effect of metformin on schizophrenia-like behaviors induced by MK-801 (dizocilpine), an N-methyl-D-aspartate (NMDA) receptor antagonist. We found that the pre-pulse inhibition (PPI) deficit caused by MK-801 could be alleviated by metformin. The hyperlocomotion in the open field test induced by chronic treatment of MK-801 was reversed by administration of metformin. Metformin has no effect on the baseline level of anxiety in normal naive rats, while metformin could relieve the anxiety-like behaviors in MK-801-treatment rats, though this effect is not reaching a significant level. Additionally, metformin could significantly ameliorate working memory impairments induced by MK-801. Moreover, the increased level of phosphorylation of Akt and GSK3β in the frontal cortex induced by MK-801 was normalized by metformin. In conclusion, our results demonstrate that metformin improved schizophrenia-like symptoms in rats, and is therefore a potential agent for the treatment of schizophrenia.

Practical Guidance on the Use of Lurasidone for the Treatment of Adults with Schizophrenia

Introduction

Lurasidone is an atypical antipsychotic that was approved in Europe in 2014 for the treatment of schizophrenia in adults aged ≥ 18 years. Clinical experience with lurasidone in Europe is currently limited, and there is therefore a need to provide practical guidance on using lurasidone for the treatment of adults with schizophrenia.

Methods

A panel of European psychiatrists with extensive experience of prescribing lurasidone was convened to provide recommendations on using lurasidone to treat adults with schizophrenia.

Results

Extensive evidence from clinical trials and the panel’s clinical experience suggest that lurasidone is as effective as other atypical agents, with the possible exception of clozapine. Lurasidone is associated with a lower propensity for metabolic side effects (in particular, weight gain) and hyperprolactinaemia than most other atypical antipsychotics and has a relatively benign neurocognitive side effect profile. Patients switching to lurasidone from another antipsychotic may experience weight reduction and/or improvements in the ability to focus/concentrate. Most side effects with lurasidone (such as somnolence) are transitory, easily managed and/or ameliorated by dose adjustment. Akathisia and extrapyramidal symptoms may occur in a minority of patients, but these can be managed effectively with dose adjustment, adjunctive therapy and/or psychosocial intervention.

Conclusions

Given the crucial importance of addressing the physical as well as mental healthcare needs of patients, lurasidone is a rational therapeutic choice for adults with schizophrenia, both in the acute setting and over the long term.

Funding

Sunovion Pharmaceuticals Europe Ltd.

Electronic supplementary material

The online version of this article (10.1007/s40120-019-0138-z) contains supplementary material, which is available to authorized users.

Revised Pharmacophore Model for 5-HT2A Receptor Antagonists Derived from the Atypical Antipsychotic Agent Risperidone

Pharmacophore models for 5-HT_2A receptor antagonists consist of two aromatic/hydrophobic regions at a given distance from a basic amine. We have previously shown that both aromatic/hydrophobic moieties are unnecessary for binding or antagonist action. Here, we deconstructed the 5-HT_2A receptor antagonist/serotonin-dopamine antipsychotic agent risperidone into smaller structural segments that were tested for 5-HT_2A receptor affinity and function. We show, again, that the entire risperidone structure is unnecessary for retention of affinity or antagonist action. Replacement of the 6-fluoro-3-(4-piperidinyl)-1,2-benz[ d]isoxazole moiety by isosteric tryptamines resulted in retention of affinity and antagonist action. Additionally, 3-(4-piperidinyl)-1,2-benz[ d]isoxazole (10), which represents less than half the structural features of risperidone, retains both affinity and antagonist actions. 5-HT_2A receptor homology modeling/docking studies suggest that 10 binds in a manner similar to risperidone and that there is a large cavity to accept various N₄-substituted analogues of 10 such as risperidone and related agents. Alterations of this "extended" moiety improve receptor binding and functional potency. We propose a new risperidone-based pharmacophore for 5-HT_2A receptor antagonist action.

Dysregulation of auditory neuroplasticity in schizophrenia

Schizophrenia is a complex brain syndrome characterized by an array of positive symptoms (delusions, hallucinations, disorganized speech), negative symptoms (alogia, apathy, avolition) and cognitive impairments (memory, executive functions). Although investigations of the cognitive deficits in schizophrenia have primarily concentrated on disturbances affecting higher-order cognitive processes, there is an increasing realization that schizophrenia also affects early sensory processing, which might, in fact, play a significant role in the development of higher-order cognitive impairments. Recent evidence suggests that many of these early sensory processing impairments possibly arise from a dysregulation of plasticity regulators in schizophrenia, resulting in either reduced plasticity or excessive unregulated plasticity. The purpose of the present manuscript is to provide a concise overview of how the dysregulation of cortical plasticity mechanisms contributes to schizophrenia symptoms with an emphasis on auditory dysplasticity and to discuss its relevance for treatment outcomes. The idea that plasticity mechanisms are not constrained only within sensitive periods suggests that many functional properties of sensory neurons can be altered throughout the lifetime.

Polymorphisms in Dopaminergic Genes in Schizophrenia and Their Implications in Motor Deficits and Antipsychotic Treatment

Dopaminergic system dysfunction is involved in schizophrenia (SCZ) pathogenesis and can mediate SCZ-related motor disorders. Recent studies have gradually revealed that SCZ susceptibility and the associated motor symptoms can be mediated by genetic factors, including dopaminergic genes. More importantly, polymorphisms in these genes are associated with both antipsychotic drug sensitivity and adverse effects. The study of genetic polymorphisms in the dopaminergic system may help to optimize individualized drug strategies for SCZ patients. This review summarizes the current progress about the involvement of the dopamine system in SCZ-associated motor disorders and the motor-related adverse effects after antipsychotic treatment, with a special focus on polymorphisms in dopaminergic genes. We hypothesize that the genetic profile of the dopaminergic system mediates both SCZ-associated motor deficits associated and antipsychotic drug-related adverse effects. The study of dopaminergic gene polymorphisms may help to predict drug efficacy and decrease adverse effects, thereby optimizing treatment strategies.