Olanzapine and quetiapine protect PC12 cells from β-amyloid peptide25-35-induced oxidative stress and the ensuing apoptosis

Peering into the mind: unraveling schizophrenia's secrets using models

Schizophrenia (SCZ) is a complex mental disorder characterized by a range of symptoms, including positive and negative symptoms, as well as cognitive impairments. Despite the extensive research, the underlying neurobiology of SCZ remain elusive. To overcome this challenge, the use of diverse laboratory modeling techniques, encompassing cellular and animal models, and innovative approaches like induced pluripotent stem cell (iPSC)-derived neuronal cultures or brain organoids and genetically engineered animal models, has been crucial. Immortalized cellular models provide controlled environments for investigating the molecular and neurochemical pathways involved in neuronal function, while iPSCs and brain organoids, derived from patient-specific sources, offer significant advantage in translational research by facilitating direct comparisons of cellular phenotypes between patient-derived neurons and healthy-control neurons. Animal models can recapitulate the different psychopathological aspects that should be modeled, offering valuable insights into the neurobiology of SCZ. In addition, invertebrates' models are genetically tractable and offer a powerful approach to dissect the core genetic underpinnings of SCZ, while vertebrate models, especially mammals, with their more complex nervous systems and behavioral repertoire, provide a closer approximation of the human condition to study SCZ-related traits. This narrative review provides a comprehensive overview of the diverse modeling approaches, critically evaluating their strengths and limitations. By synthesizing knowledge from these models, this review offers a valuable source for researchers, clinicians, and stakeholders alike. Integrating findings across these different models may allow us to build a more holistic picture of SCZ pathophysiology, facilitating the exploration of new research avenues and informed decision-making for interventions.

Cognitive improvements linked to lysophosphatidylethanolamine after olanzapine treatment in drug-naïve first-episode schizophrenia

BACKGROUND

Cognitive impairments are a hallmark symptom of schizophrenia (SCZ). Phosphatidylethanolamine (PE) is the second most abundant phospholipid in mammalian cells, yet its role in cognitive deficits remains unexplored. The aim of this study was to investigate the association between plasma LysoPE and cognitive improvements following olanzapine monotherapy in drug-naïve first-episode (DNFE) SCZ patients.

METHODS

Twenty-five female DNFE SCZ patients were treated with olanzapine for four weeks, and cognitive function was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) at baseline and after the 4-week follow-up. Utilizing an untargeted ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)-based metabolomics approach, we measured LysoPE concentrations.

RESULTS

Significant improvements in immediate and delayed memory domains were observed post-treatment. We identified nine differential LysoPE species after olanzapine monotherapy, with increased concentrations for all LysoPE except LysoPE (22:6). Elevated LysoPE (22:1) concentration positively correlated with cognitive improvement in patients. Baseline LysoPE (16:1) emerged as a predictive factor for cognitive improvement following olanzapine monotherapy.

CONCLUSIONS

This study offers preliminary evidence for the involvement of LysoPE in cognitive improvements observed in drug-naïve first-episode SCZ patients after olanzapine treatment.

Molecular regulation of calcium-sensing receptor (CaSR)-mediated signaling

Calcium-sensing receptor (CaSR), a family C G-protein-coupled receptor, plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca2+, Mg2+, amino acids (e.g., L-Trp and L-Phe), small peptides, anions (e.g., HCO3 - and PO4 3-), and pH. CaSR-mediated intracellular Ca2+ signaling regulates a diverse set of cellular processes including gene transcription, cell proliferation, differentiation, apoptosis, muscle contraction, and neuronal transmission. Dysfunction of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia, and neonatal severe hyperparathyroidism. CaSR also influences calciotropic disorders, such as osteoporosis, and noncalciotropic disorders, such as cancer, Alzheimer's disease, and pulmonary arterial hypertension. This study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands, as well as exogenous positive allosteric modulators and negative allosteric modulators. The establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum, trafficking, cell surface expression, endocytosis, degradation, and signaling pathways. The roles of these proteins in Ca2+-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.

Carob Seed Peels Effect on Cognitive Impairment and Oxidative Stress Status in Methionine-Induced Mice Models of Schizophrenia

Background:Ceratonia siliqua L. (Carob tree) is a Mediterranean evergreen, well known for its medicinal properties. The different parts of Carob were proven to exert antidiabetic, antibacterial, antifungal, and antiproliferative effects. Hence, the present paper aims to validate the positive correlation between the high antioxidant activity of carob seed peels and the improvement of negative symptoms of schizophrenia. Materials & Methods: The antioxidant activity was carried out using the β-carotene test. Methionine and carob seed peels (CSP) extracts (50 and 100 mg/kg) were orally administrated to mice for a week. After administration, behavioral tests were assessed using the Y-maze, elevated plus maze, and forced swimming tests, as well as the novel object recognition task. Furthermore, the oxidative stress status was evaluated by analyzing the levels of the antioxidant enzymes: Superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde levels (MDA). Results: Both extracts exhibited remarkable antioxidant activity and showed antibacterial effect against Gram-positive bacteria tested (Bacillus subtilis and Staphylococcus aureus) and against Pseudomonas aeruginosa (Gram-negative). Therefore, Escherichia coli was very resistant. The behavioral tests proved the efficacy of CSP in enhancing the cognitive impairment of animal models of schizophrenia. Hence, the stated correlation between oxidative stress and schizophrenia was confirmed by the increased SOD and GPx activities and the decreased MDA level. Conclusions: The present study gave further confirmation of the potential correlation between oxidative stress and the development of psychiatric disorders and highlighted the use of natural antioxidants, especially Ceratonia siliqua L. in the improvement of cognitive impairment in the dementia of schizophrenia.

Imipramine and olanzapine block apoE4-catalyzed polymerization of Aβ and show evidence of improving Alzheimer’s disease cognition

Background

The apolipoprotein E (APOE) ε4 allele confers the strongest risk for late-onset Alzheimer’s disease (AD) besides age itself, but the mechanisms underlying this risk are debated. One hypothesis supported by evidence from multiple labs is that apoE4 binds to the amyloid-β (Aβ) peptide and catalyzes its polymerization into neurotoxic oligomers and fibrils. Inhibiting this early step in the amyloid cascade may thereby reduce or prevent neurodegeneration and AD.

Methods

Using a design of experiments (DOE) approach, we developed a high-throughput assay to identify inhibitors of apoE4-catalyzed polymerization of Aβ into oligomers and fibrils. We used it to screen the NIH Clinical Collection of small molecule drugs tested previously in human clinical trials. We then evaluated the efficacy and cytotoxicity of the hit compounds in primary neuron models of apoE4-induced Aβ and phosphorylated tau aggregation. Finally, we performed retrospective analyses of the National Alzheimer’s Coordinating Center (NACC) clinical dataset, using Cox regression and Cox proportional hazards models to determine if the use of two FDA-approved hit compounds was associated with better cognitive scores (Mini-Mental State Exam), or improved AD clinical diagnosis, when compared with other medications of the same clinical indication.

Results

Our high-throughput screen identified eight blood-brain barrier (BBB)-permeable hit compounds that reduced apoE4-catalyzed Aβ oligomer and fibril formation in a dose-dependent manner. Five hit compounds were non-toxic toward cultured neurons and also reduced apoE4-promoted Aβ and tau neuropathology in a dose-dependent manner. Three of the five compounds were determined to be specific inhibitors of apoE4, whereas the other two compounds were Aβ or tau aggregation inhibitors. When prescribed to AD patients for their normal clinical indications, two of the apoE4 inhibitors, imipramine and olanzapine, but not other (non-hit) antipsychotic or antidepressant medications, were associated with improvements in cognition and clinical diagnosis, especially among APOE4 carriers.

Conclusions

The critical test of any proposed AD mechanism is whether it leads to effective treatments. Our high-throughput screen identified two promising FDA-approved drugs, imipramine and olanzapine, which have no structural, functional, or clinical similarities other than their shared ability to inhibit apoE4-catalyzed Aβ polymerization, thus identifying this mechanism as an essential contribution of apoE4 to AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-01020-9.

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

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

Olanzapine Ameliorates Ischemic Stroke-like Pathology in Gerbils and H2O2-Induced Neurotoxicity in SH-SY5Y Cells via Inhibiting the MAPK Signaling Pathway

Olanzapine (OLNZ) is used to treat psychotic disorders. To look into the neurological basis of this phenomenon, we investigated the neuroprotective effects of OLNZ in gerbils and SH-SY5Y cells. Gerbils were subjected to transient global cerebral ischemia (TGCI) by blocking both common carotid arteries, and OLNZ (10 mg/kg) was injected intraperitoneally. Hydrogen peroxide (H₂O₂) was used to induce oxidative-stress-mediated damage in the SH-SY5Y cells. The results indicated that OLNZ administration markedly reduced neuron damage and glial cell triggering within CA1 zone of the hippocampus. We used RNA sequencing to assess the numbers of up-and downregulated genes involved in TGCI. We found that OLNZ treatment downregulated the expression of complement-component-related genes and the expression of mitogen-activated protein kinases (MAPKs) in the hippocampus. In cells, OLNZ co-treatment significantly improved cell viability and reduced lactate dehydrogenase (LDH), and reactive oxygen species (ROS) generation. Expression of antioxidant superoxide dismutase-1,2 enzymes (SOD-1, SOD-2) was also intensely upregulated by OLNZ, while the expression of MAPKs and NF-κB were reduced. Co-incubation with OLNZ also regulated apoptosis-related proteins Bax/Bcl-2 expression. Finally, the results demonstrated that treatment with OLNZ showed neuroprotective effects and that the MAPK pathway could involve in the protective effects.

Altered Antioxidant Defenses in Drug-Naive First Episode Patients with Schizophrenia Are Associated with Poor Treatment Response to Risperidone: 12-Week Results from a Prospective Longitudinal Study

Abnormal redox regulation is thought to contribute to schizophrenia (SCZ). Accumulating studies have shown that the plasma antioxidant enzyme activity is closely associated with the course and outcome in antipsychotics-naïve first-episode (ANFE) patients with SCZ. The main purpose of this study was to investigate the effect of risperidone on oxidative stress markers in ANFE patients and the relationship between risperidone response and changes in oxidative stress markers. Plasma activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) enzyme, total antioxidant status (TAS), and malondialdehyde (MDA) levels were measured in 354 ANFE patients and 152 healthy controls. The clinical symptoms were evaluated by the Positive and Negative Syndrome Scale (PANSS). Patients received risperidone monotherapy for 12 weeks and oxidative stress markers and PANSS were measured at baseline and at follow-up. Compared with healthy controls, the patients exhibited higher activities of SOD, CAT, and TAS levels, but lower MDA levels and GPx activity. A comparison between 168 responders and 50 non-responders at baseline and 12-week follow-up showed that GPx activity decreased in both groups after treatment. Moreover, GPx activity decreased less in responders and was higher in responders than in non-responders at follow-up. These results demonstrate that the redox regulatory system and antioxidant defense enzymes may have predictive value for the response of ANFE patients to risperidone treatment.

The Role of Mitochondria in Mood Disorders: From Physiology to Pathophysiology and to Treatment

Mitochondria are cellular organelles involved in several biological processes, especially in energy production. Several studies have found a relationship between mitochondrial dysfunction and mood disorders, such as major depressive disorder and bipolar disorder. Impairments in energy production are found in these disorders together with higher levels of oxidative stress. Recently, many agents capable of enhancing antioxidant defenses or mitochondrial functioning have been studied for the treatment of mood disorders as adjuvant therapy to current pharmacological treatments. A better knowledge of mitochondrial physiology and pathophysiology might allow the identification of new therapeutic targets and the development and study of novel effective therapies to treat these specific mitochondrial impairments. This could be especially beneficial for treatment-resistant patients. In this article, we provide a focused narrative review of the currently available evidence supporting the involvement of mitochondrial dysfunction in mood disorders, the effects of current therapies on mitochondrial functions, and novel targeted therapies acting on mitochondrial pathways that might be useful for the treatment of mood disorders.

Role of magnetic resonance spectroscopy in cerebral glutathione quantification for youth mental health: A systematic review

AIM

Oxidative stress is strongly implicated in many psychiatric disorders, which has resulted in the development of new interventions to attempt to perturb this pathology. A great deal of attention has been paid to glutathione, which is the brain's dominant antioxidant and plays a fundamental role in removing free radicals and other reactive oxygen species. Measurement of glutathione concentration in the brain in vivo can provide information on redox status and potential for oxidative stress to develop. Glutathione might also represent a marker to assess treatment response.

METHODS

This paper systematically reviews studies that assess glutathione concentration (measured using magnetic resonance spectroscopy) in various mental health conditions.

RESULTS

There is limited evidence showing altered brain glutathione concentration in mental disorders; the best evidence suggests glutathione is decreased in depression, but is not altered in bipolar disorder. The review then outlines the various methodological options for acquiring glutathione data using spectroscopy.

CONCLUSIONS

Analysis of the minimum effect size measurable in existing studies indicates that increased number of participants is required to measure subtle but possibly important differences and move the field forward.

Radioprotective effect of olanzapine as an anti-psychotic drug against genotoxicity and apoptosis induced by ionizing radiation on human lymphocytes

Olanzapine (OLA), is prescribed as an anti-psychotic medicine in schizophrenia patients. In this study, the protective effect of OLA against genotoxicity and apoptosis induced by ionizing radiation in human healthy lymphocytes was evaluated. At first, the antioxidant activities of OLA were assayed by two different methods as free radical scavenging with DPPH (2,2-diphenyl-1-picryl-hydrazyl) and ferric reducing power methods. In in vitro experiment, human blood samples were treated with OLA at various concentrations (0.25-20 μM) for 3 h and then were exposed to X-ray at a dose of 150 cGy. The genotoxicity was assessed in binucleated human lymphocytes with micronuclei assay. The apoptotic lymphocytes were assessed by flow cytometry in OLA treated and/or irradiated lymphocytes. OLA exhibited free radical scavenging and reducing power activities more than ascorbic acid. The results showed that the lymphocytes treated with OLA and later exposed to IR presented lower frequencies of micronuclei and apoptosis compared to the control sample which was irradiated and not treated to OLA. The maximum radioprotection was observed at 20 μM of OLA with 83% of efficacy. The present study suggested the protective role for OLA in protection radiation-induced genetic damage and apoptosis induced by ionizing irradiation in human normal cells.

Chronic administration of quetiapine attenuates the phencyclidine-induced recognition memory impairment and hippocampal oxidative stress in rats

The underlying mechanism of atypical antipsychotics in treating cognitive impairment in schizophrenia is unclear. The aim of the present study was to evaluate the effects of quetiapine, an atypical antipsychotic drug, on object recognition memory and hippocampal oxidative stress in a phencyclidine (PCP) rat model of schizophrenia. Rats were treated with chronic quetiapine (10 mg/kg/day, intraperitoneally) for 16 days or acute quetiapine (10 mg/kg/day, intraperitoneally) on day 16. On day 16, 1 h after the administration of quetiapine, the rats were administered PCP (50 mg/kg, subcutaneously). After the last object recognition behavioral test on day 18, the rats were killed for the measurement of hippocampal protein expression of nitrotyrosine, a protein marker of oxidative stress. The results showed that chronic quetiapine significantly attenuated object recognition memory impairment and hippocampal oxidative stress in the PCP-injected rats. These suggest that the attenuating effect of chronic quetiapine on hippocampal oxidative stress may be related to quetiapine's beneficial effects on object recognition memory in PCP rats, and further suggest that neuroprotective mechanisms are involved in chronic quetiapine treatment.

Repeated olanzapine treatment mitigates PTSD like symptoms in rats with changes in cell signaling factors

Post Traumatic Stress Disorder is an anxiety disorder with prolonged distortion of rational behavior. In this study, we report the preclinical potential of olanzapine (OLZ) in the treatment of PTSD. Since the atypical antipsychotics have modulating effects on cell protective and destructive factors, we tested the effects of OLZ in PTSD regarding these cell modulating factors. Rats, when subjected to stress-restress (SRS) model of PTSD, showed a derangement in cell protective factors like the decline in BDNF, ERK, and CREB. While the adversarial factors like caspase-3 were enhanced. Four weeks treatment with OLZ at doses of 1 and 10 mg/kg significantly mitigated the SRS-induced derangement related to PTSD. OLZ at doses of 1 and 10 mg/kg enhanced BDNF, ERK and CREB levels which were reduced by SRS in PTSD animals. Further, at the fore mentioned doses it also inhibited the elevation of caspase-3 a downstream apoptotic factor. Besides, OLZ also showed mitigation in behavioral alterations related to anxiety and memory brought about by PTSD. These effects of OLZ were comparable to that of paroxetine a clinically approved drug for PTSD in terms of biochemical and behavioral assessments indicating its anti-PTSD potential.

Mechanisms Underpinning the Polypharmacy Effects of Medications in Psychiatry

BACKGROUND

Bipolar disorder is a mental health condition with progressive social and cognitive function disturbances. Most patients' treatments are based on polypharmacy, but with no biological basis and little is known of the drugs' interactions. The aim of this study was to analyze the effects of lithium, valproate, quetiapine, and lamotrigine, and the interactions between them, on markers of inflammation, bioenergetics, mitochondrial function, and oxidative stress in neuron-like cells and microglial cells.

METHODS

Neuron-like cells and lipopolysaccharide-stimulated C8-B4 cells were treated with lithium (2.5 mM), valproate (0.5 mM), quetiapine (0.05 mM), and lamotrigine (0.05 mM) individually and in all possible combinations for 24 h. Twenty cytokines were measured in the media from lipopolysaccharide-stimulated C8-B4 cells. Metabolic flux analysis was used to measure bioenergetics, and real-time PCR was used to measure the expression of mitochondrial function genes in neuron-like cells. The production of superoxide in treated cells was also assessed.

RESULTS

The results suggest major inhibitory effects on proinflammatory cytokine release as a therapeutic mechanism of these medications when used in combination. The various combinations of medications also caused overexpression of PGC1α and ATP5A1 in neuron-like cells. Quetiapine appears to have a proinflammatory effect in microglial cells, but this was reversed by the addition of lamotrigine independent of the drug combination.

CONCLUSION

Polypharmacy in bipolar disorder may have antiinflammatory effects on microglial cells as well as effects on mitochondrial biogenesis in neuronal cells.

Neuroprotection in Schizophrenia and Its Therapeutic Implications

Schizophrenia is a chronic and debilitating mental disorder. The persisting negative and cognitive symptoms that are unresponsive to pharmacotherapy reveal the impairment of neuroprotective aspects of schizophrenia. In this review, of the several neuroprotective factors, we mainly focused on neuroinflammation, neurogenesis, and oxidative stress. We conducted a narrative and selective review. Neuroinflammation is mainly mediated by pro-inflammatory cytokines and microglia. Unlike peripheral inflammatory responses, neuroinflammation has a role in various neuronal activities such as neurotransmission neurogenesis. The cross-talk between neuroinflammation and neurogenesis usually has beneficial effects in the CNS under physiological conditions. However, uncontrolled and chronic neuroinflammation exert detrimental effects such as neuronal loss, inhibited neurogenesis, and excessive oxidative stress. Neurogenesis is also a major component of neuroprotection. Adult neurogenesis mainly occurs in the hippocampal region, which has an important role in memory formation and processing. Impaired neurogenesis and an ineffective response to antipsychotics may be thought to indicate a deteriorating course of schizophrenia. Oxidative stress and excessive dopaminergic neurotransmission may create a vicious cycle and consequently disturb NMDA receptor-mediated glutamatergic neurotransmission. Based on the current evidences, several neuroprotective therapeutic approaches have been reported to be efficacious for improving psychopathology, but further longitudinal and large-sample based studies are needed.

Inhibition of phosphodiesterase-4 reverses the cognitive dysfunction and oxidative stress induced by Aβ25-35 in rats

Phosphodiesterase-4 (PDE4) inhibitors prevent the breakdown of the second messenger cAMP and have been demonstrated to improve learning in several animal models of cognition. In this study, we explored the antioxidative effects of rolipram in Alzheimer's disease (AD) by using bilateral Aβ25-35 injection into the hippocampus of rats, which were used as an AD model. Rats received 3 intraperitoneal (i.p.) doses of rolipram (0.1, 0.5 and 1.25 mg/kg) daily after the injection of Aβ25-35 for 25 days. Chronic administration of rolipram prevented the memory impairments induced by Aβ25-35, as assessed using the passive avoidance test and the Morris water maze test. Furthermore, rolipram significantly reduced the oxidative stress induced by Aβ25-35, as evidenced by the decrease in the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and restored the reduced GSH levels and superoxide dismutase (SOD) activity. Moreover, western blotting and real-time reverse transcription polymerase chain reaction (RT-PCR) analysis showed that rolipram remarkably upregulated thioredoxin (Trx) and inhibited the inducible nitric oxide synthase/nitric oxide (iNOS/NO) pathway in the hippocampus. These results demonstrated that rolipram improved the learning and memory abilities in an Aβ25-35-induced AD rat model. The mechanism underlying these effects may be due to the noticeable antioxidative effects of rolipram.

Oxidative Stress Implications in the Affective Disorders: Main Biomarkers, Animal Models Relevance, Genetic Perspectives, and Antioxidant Approaches

The correlation between the affective disorders and the almost ubiquitous pathological oxidative stress can be described in a multifactorial way, as an important mechanism of central nervous system impairment. Whether the obvious changes which occur in oxidative balance of the affective disorders are a part of the constitutive mechanism or a collateral effect yet remains as an interesting question. However it is now clear that oxidative stress is a component of these disorders, being characterized by different aspects in a disease-dependent manner. Still, there are a lot of controversies regarding the relevance of the oxidative stress status in most of the affective disorders and despite the fact that most of the studies are showing that the affective disorders development can be correlated to increased oxidative levels, there are various studies stating that oxidative stress is not linked with the mood changing tendencies. Thus, in this minireview we decided to describe the way in which oxidative stress is involved in the affective disorders development, by focusing on the main oxidative stress markers that could be used mechanistically and therapeutically in these deficiencies, the genetic perspectives, some antioxidant approaches, and the relevance of some animal models studies in this context.

Blocking the phosphatidylinositol 3-kinase pathway inhibits neuregulin-1-mediated rescue of neurotoxicity induced by Aβ1-42

OBJECTIVES

Neuregulin-1 (NRG1) has an important role in both the development and the plasticity of the brain as well as neuroprotective properties. In this study, we investigated the downstream pathways of NRG1 signalling and their role in the prevention of Aβ1-42 -induced neurotoxicity.

METHODS

Lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) generation, superoxide dismutase (SOD) activity and TUNEL staining were assayed to examine the neuroprotective properties in primary rat cortical neurons.

KEY FINDINGS

The inhibition of PI3K/Akt activation abolished the ability of NRG1 to prevent Aβ1-42 -induced LDH release and increased TUNEL-positive cell count and reactive oxygen species accumulation in primary cortical neurons.

CONCLUSIONS

Our results demonstrate that NRG1 signalling exerts a neuroprotective effect against Aβ1-42 -induced neurotoxicity via activation of the PI3K/Akt pathway. Furthermore, this suggests that NRG1 has neuroprotective potential for the treatment of AD.

The cuprizone-induced changes in (1)H-MRS metabolites and oxidative parameters in C57BL/6 mouse brain: Effects of quetiapine

Cuprizone is a copper-chelating agent and able to induce oligodendrocyte loss and demyelination in C57BL/6 mouse brain. Recent studies have used the cuprizone-fed mouse as an animal model of schizophrenia to examine putative roles of altered oligodendrocytes in this mental disorder. The present study reported the effects of cuprizone on the brain metabolites and oxidative parameters with the aim of providing neurochemical evidence for the application of the cuprizone mouse as an animal model of schizophrenia. In addition, we examined effects of quetiapine on the cuprizone-induced changes in brain metabolites and oxidative parameters; this atypical antipsychotic was shown to ameliorate the cuprizone-induced demyelination and behavioral changes in previous studies. C57BL/6 mice were fed a standard rodent chow without or with cuprizone (0.2% w/w) for four weeks during which period they were given sterilized saline or quetiapine in saline. The results of the proton magnetic resonance spectroscopy (1H-MRS) showed that cuprizone-feeding decreased (1)H-MRS signals of N-acetyl-l-aspartate (NAA), total NAA (NAA + NAAG), and choline-containing compounds (phosphorylcholine and glycerophosphorylcholine), suggestive of mitochondrial dysfunction in brain neurons. Biochemical analyses showed lower activities of catalase and glutathione peroxidase, but higher levels of malondialdehyde and H2O2 in the brain tissue of cuprizone-fed mice, indicative of an oxidative stress. These cuprizone-induced changes were effectively relieved in the mice co-administered with cuprizone and quetiapine, although the antipsychotic alone showed no effect. These findings suggest the toxic effects of cuprizone on mitochondria and an antioxidant capacity of quetiapine, by which this antipsychotic relieves the cuprizone-induced mitochondrial dysfunction in brain cells.

Quetiapine mitigates the neuroinflammation and oligodendrocyte loss in the brain of C57BL/6 mouse following cuprizone exposure for one week

This study aimed at examining effects of quetiapine (QTP), an atypical antipsychotic, on the behaviors of mice which had consumed cuprizone (CPZ)-containing diet for one week and on inflammatory reactions and oligodendrocyte (OL) loss in brains of them. Young adult C57BL/6 mice, after fed CPZ-containing diet (0.2%, w/w) for one week, showed an increase in the locomotor activity in the open-field, and a decreased exploration time in the novel object recognition (NOR) test compared to controls. But, these changes were not seen in mice co-administered with QTP and CPZ. All mice in the four groups showed comparable performances in Y-maze test. After the behavioral tests, mice were killed and their brains were processed for immunohistochemical and immunofluorescence staining to examine OLs, astrocytes and microglia. The levels of proinflammatory cytokines TNF-α and IL-6 in certain brain regions were also evaluated by ELISA method. Mice in the NS+CPZ group showed fewer OLs, more activated astrocytes and microglia with higher immunofluorescence intensity in the examined brain regions of the corpus callosum, caudate putamen, cerebral cortex, and hippocampus. The levels of TNF-α and IL-6 in some of these brain regions were also increased. But these changes were completely blocked or effectively ameliorated in the QTP+CPZ group. These results demonstrated an anti-inflammatory effect of QTP in CPZ-exposed mice and this action may contribute to its protection on OLs and beneficial effects on the CPZ-induced behavioral changes in these mice.

Paliperidone regulates intracellular redox system in rat brain: Role of purine mechanism

OBJECTIVE

The treatment of schizophrenia is multifactorial, with antipsychotic medications comprising a major part of treatment. Paliperidone is a newly commercialized antipsychotic whose formulation includes the principal active metabolite risperidone, 9-hydroxyrisperidone. Ever since the relationship between schizophrenia and oxidative stress was first demonstrated, many studies have been conducted in order to probe the potential protective effects of antipsychotic drugs on the oxidant-antioxidant system and lipid peroxidation. The basic aim of this study is to determine the effects of the newly marketed drug paliperidone on the activities of the enzymes adenosine deaminase (ADA), xanthine oxidase (XO), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) as well as on malondialdehyde (MDA) and nitric oxide (NO) levels in rat brain tissues.

METHODS

Twenty male Sprague-Dawley rats were used for the study, which were divided into two equal groups. The first was the control group (n = 10) and the second was the paliperidone group (n = 10). Saline was administered once daily for 14 days in the control group. In the paliperidone group, paliperidone was administered once daily with a dose of 1 mg/kg for 14 days. All rats were sacrificed at the end of the fourteenth day. Brain samples were collected and then analyzed.

RESULTS

Our results demonstrated that paliperidone significantly decreased the activities of ADA (P = 0.015), XO (P = 0.0001), and CAT (P = 0.004) while insignificantly increasing the activity of SOD (P = 0.49), MDA (P = 0.71), and NO (P = 0.26) levels in rat brain tissues. In addition, paliperidone insignificantly decreased the activity of GSH-Px (P = 0.30) compared to the control group in rat brain tissues.

DISCUSSION

In conclusion, the data obtained in this study suggest that paliperidone can positively alter antioxidant status and, accordingly, can offer positive outcomes in the treatment of schizophrenia by reducing activity in the enzymes ADA and XO, which are associated with purine metabolism. We believe that such a comprehensive approach used with other antipsychotic drugs warrants further study.

Role of quetiapine beyond its clinical efficacy in bipolar disorder: From neuroprotection to the treatment of psychiatric disorders (Review)

The aim of the present review was to discuss the following aspects of treatment with quetiapine in psychiatric disorders: i) Neurocognition and functional recovery in bipolar disorder (BD); ii) neuroprotective profile in different models; and iii) potential off-label indications. A PubMed search was conducted of articles published in English between 2000 and 2012 on quetiapine, cross-referenced with the terms ‘anxiety’, ‘attention deficit disorder’, ‘borderline personality disorder’, ‘dementia’, ‘insomnia’, ‘major depressive disorder’ (MDD), ‘obsessive-compulsive disorder’, ‘post-traumatic stress disorder’, ‘remission’, ‘cognition’, ‘neurobiology’, ‘neuroprotection’, ‘efficacy’ and ‘effectiveness’. Articles were selected from meta-analyses, randomized clinical trials and open trials, and the results were summarized. Quetiapine, when studied in off-label conditions, has shown efficacy as a monotherapy in MDD and general anxiety disorder. Quetiapine also appears to exhibit a small beneficial effect in dementia. The review of other conditions was affected by methodological limitations that precluded any definitive conclusions on the efficacy or safety of quetiapine. Overall, the present review shows evidence supporting a potential role for quetiapine in improving cognition, functional recovery and negative symptoms in a cost-effective manner in BD. These benefits of quetiapine are potentially associated with its well-described neuroprotective effects; however, further studies are clearly warranted.

Quetiapine mitigates the ethanol-induced oxidative stress in brain tissue, but not in the liver, of the rat

Quetiapine, an atypical antipsychotic, has been employed to treat alcoholic patients with comorbid psychopathology. It was shown to scavenge hydroxyl radicals and to protect cultured cells from noxious effects of oxidative stress, a pathophysiological mechanism involved in the toxicity of alcohol. This study compared the redox status of the liver and the brain regions of prefrontal cortex, hippocampus, and cerebellum of rats treated with or without ethanol and quetiapine. Ethanol administration for 1 week induced oxidative stress in the liver and decreased the activity of glutathione peroxidase and total antioxidant capacity (TAC) there. Coadministration of quetiapine did not protect glutathione peroxidase and TAC in the liver against the noxious effect of ethanol, thus was unable to mitigate the ethanol-induced oxidative stress there. The ethanol-induced alteration in the redox status in the prefrontal cortex is mild, whereas the hippocampus and cerebellum are more susceptible to ethanol intoxication. For all the examined brain regions, coadministration of quetiapine exerted effective protection on the antioxidants catalase and total superoxide dismutase and on the TAC, thus completely blocking the ethanol-induced oxidative stress in these brain regions. These protective effects may explain the clinical observations that quetiapine reduced psychiatric symptoms intensity and maintained a good level of tolerability in chronic alcoholism with comorbid psychopathology.

Quetiapine reduces microglial number in the hippocampus of a transgenic mouse model of Alzheimer's disease

Previous studies have suggested that the cerebral microglia activation was associated with Aβ plaques, whereas quetiapine, an atypical antipsychotic drug, decreased Aβ levels in Alzheimer's disease (AD) mice. The aim of the present study was to evaluate the effects of quetiapine on microglial activation in an amyloid precursor protein/presenilin-1 double transgenic mouse model of AD. Nontransgenic and transgenic mice were treated with quetiapine (0 or 5 mg/kg/day) in drinking water from the age of 2 months. After 10 months of continuous quetiapine administration, the mice were killed, and hippocampal microglial activation was measured by immunohistochemistry staining of CD11b-positive cells. The results showed that quetiapine significantly decreased the number of CD11b-positive cells and β-amyloid peptide levels in the hippocampus of transgenic mice. These suggest that quetiapine can attenuate microglia activation in an amyloid precursor protein/presenilin-1 transgenic mouse model of AD, and this may be related to quetiapine's beneficial effects in AD treatment.

Immune system: a possible nexus between cannabinoids and psychosis

BACKGROUND

Endocannabinoid system is involved in the regulation of the brain-immune axis. Cannabis consumption is related with the development, course, and severity of psychosis. The epidemiological evidence for increased occurrence of immunological alterations in patients with psychosis has not been sufficiently addressed. The aim of this review is to establish whether there is any scientific evidence of the influence of cannabinoids on aspects of immunity that affect susceptibility to psychotic disorder induction.

METHODS

A comprehensive search of PubMed/MEDLINE, EMBASE and ISI Web of Knowledge was performed using combinations of key terms distributed into three blocks: "immune", "cannabinoid", and "endocannabinoid receptor". Studies were considered to be eligible for the review if they were original articles, they reported a quantitative or qualitative relation between cannabinoid ligands, their receptors, and immune system, and they were carried out in vitro or in mammals, included humans. All the information was systematically extracted and evaluated.

RESULTS

We identified 122 articles from 446 references. Overall, endocannabinoids enhanced immune response, whereas exogenous cannabinoids had immunosuppressant effects. A general change in the immune response from Th1 to Th2 was also demonstrated for cannabinoid action. Endogenous and synthetic cannabinoids also modulated microglia function and neurotransmitter secretion.

CONCLUSION

The actions of cannabinoids through the immune system are quite regular and predictable in the peripheral but remain fuzzy in the central nervous system. Despite this uncertainty, it may be hypothesized that exposure to exocannabinoids, in particular during adolescence might prompt immunological dysfunctions that potentially cause a latent vulnerability to psychosis. Further investigations are warranted to clarify the relationship between the immunological effects of cannabis and psychosis.

Astrocyte-dependent protective effect of quetiapine on GABAergic neuron is associated with the prevention of anxiety-like behaviors in aging mice after long-term treatment

Previous studies have demonstrated that quetiapine (QTP) may have neuroprotective properties; however, the underlying mechanisms have not been fully elucidated. In this study, we identified a novel mechanism by which QTP increased the synthesis of ATP in astrocytes and protected GABAergic neurons from aging-induced death. In 12-month-old mice, QTP significantly improved cell number of GABAegic neurons in the cortex and ameliorated anxiety-like behaviors compared to control group. Complimentary in vitro studies showed that QTP had no direct effect on the survival of aging GABAergic neurons in culture. Astrocyte-conditioned medium (ACM) pretreated with QTP (ACMQTP) for 24 h effectively protected GABAergic neurons against aging-induced spontaneous cell death. It was also found that QTP boosted the synthesis of ATP from cultured astrocytes after 24 h of treatment, which might be responsible for the protective effects on neurons. Consistent with the above findings, a Rhodamine 123 test showed that ACMQTP, not QTP itself, was able to prevent the decrease in mitochondrial membrane potential in the aging neurons. For the first time, our study has provided evidence that astrocytes may be the conduit through which QTP is able to exert its neuroprotective effects on GABAergic neurons. The neuroprotective properties of quetiapine (QTP) have not been fully understood. Here, we identify a novel mechanism by which QTP increases the synthesis of ATP in astrocytes and protects GABAergic neurons from aging-induced death in a primary cell culture model. In 12-month-old mice, QTP significantly improves cell number of GABAegic neurons and ameliorates anxiety-like behaviors. Our study indicates that astrocytes may be the conduit through which QTP exerts its neuroprotective effects on GABAergic neurons.

Differential effects of antipsychotics on the development of rat oligodendrocyte precursor cells exposed to cuprizone

Cuprizone (CPZ) is a copper-chelating agent and has been shown to induce white matter damage in mice and rats. The compromised white matter and oligodendrocytes (OLs) respond to some antipsychotics in vivo. However, little is known about the effects of antipsychotics on cultured OLs in the presence of CPZ. The aim of this study was to examine effects of some antipsychotics on developing OLs in the presence of CPZ. Oligodendrocyte progenitor cells (OPCs) were prepared from rat embryos; OLs at different developing stages were labeled with specific antibodies; levels of CNP and MBP proteins in mature OLs were assessed by Western-blot analysis; malondialdehyde (MDA) levels and activity of catalase were evaluated as well for an assessment of oxidative stress and antioxidative status. In immunofluorescent staining, CPZ was shown to inhibit the differentiation of cultured OPCs into O4-positive cells, reduce the maturation of O4-positive cells into CNP- and MBP-positive cells, and decrease levels of CNP and MBP in mature OLs. These inhibitory effects of CPZ were ameliorated by clozapine and quetiapine (QUE), but not by haloperidol and olanzapine. Further experiments were performed to explore the mechanism of the protective effects of QUE. QUE attenuated the decreases in CNP and MBP in CPZ-treated OLs, and blocked the CPZ-induced increase in MDA and decrease in catalase activity in cultured OLs. These results are relevant to the pathophysiology and treatment of schizophrenia considering the aberrant white matter development and evidence suggesting the derangement of the oxidant and antioxidant defense system in some of the patients with schizophrenia.

Taurine and glutathione in plasma and cerebrospinal fluid in olanzapine treated patients with schizophrenia

Oxidative stress has been implicated in the pathophysiology of schizophrenia. Taurine and glutathione (GSH) have antioxidant and central nervous system protective properties, and are proposed to be involved in the pathology of schizophrenia. The aim of this study was to compare the blood and cerebrospinal fluid (CSF) levels of taurine and GSH in patients with schizophrenia, medicated with oral olanzapine, compared with controls. In total, 37 patients with schizophrenia and 45 healthy volunteers were recruited. We found the plasma taurine levels to be elevated in patients compared with controls. No differences were, however, found between patients and controls regarding taurine in CSF or GSH concentrations in plasma and CSF. Moreover, in the patient group no correlations between taurine and GSH levels and the symptoms or function of the disorder were found. The higher levels of plasma but not CSF taurine in patients with schizophrenia treated with OLA may implicate the involvement of taurine in the pathophysiology of the disease. The absence of GSH differences both in plasma and CSF between patients and controls is interesting in the perspective of earlier research proposing a dysregulation of GSH metabolism as a vulnerability factor for the development of schizophrenia.

Neuroprotective effects of quetiapine on neuronal apoptosis following experimental transient focal cerebral ischemia in rats

OBJECTIVE

This study was undertaken in the belief that the atypical antipsychotic drug quetiapine could prevent apoptosis in the penumbra region following ischemia, taking into account findings that show 5-hydroxytryptamine-2 receptor blockers can prevent apoptosis.

METHODS

We created 5 groups, each containing 6 animals. Nothing was done on the K-I group used for comparisons with the other groups to make sure adequate ischemia had been achieved. The K-II group was sacrificed on the 1st day after transient focal cerebral ischemia and the K-III group on the 3rd day. The D-I group was administered quetiapine following ischemia and sacrificed on the 1st day while the D-II group was administered quetiapine every day following the ischemia and sacrificed on the 3rd day. The samples were stained with the immunochemical TUNEL method and the number of apoptotic cells were counted.

RESULTS

There was a significant difference between the first and third day control groups (K-II/K-III : p=0.004) and this indicates that apoptotic cell death increases with time. This increase was not encountered in the drug groups (D-I/D-II : p=1.00). Statistical analysis of immunohistochemical data revealed that quetiapine decreased the apoptotic cell death that normally increased with time.

CONCLUSION

Quetiapine is already in clinical use and is a safe drug, in contrast to many substances that are used to prevent ischemia and are not normally used clinically. Our results and the literature data indicate that quetiapine could help both as a neuronal protector and to resolve neuropsychiatric problems caused by the ischemia in cerebral ischemia cases.

Quetiapine fumarate for the treatment of multiple sclerosis: focus on myelin repair

Multiple sclerosis (MS) is a central nervous system disorder that is associated with progressive oligodendrocyte and neuronal loss, axonal degeneration, and demyelination. Several medications that mitigate immune abnormalities reduce both the frequency of relapses and inflammation on magnetic resonance imaging, leading to improved outcomes for people with the relapsing-remitting form of MS. However, there are no treatments for the progressive forms of MS where neurons and axons continue to degenerate; here, neuroprotective therapies, or medications that rebuild myelin to confer axonal well-being, may be useful. Quetiapine fumarate is an atypical antipsychotic with reported remyelinating and neuroprotective properties in inflammatory and noninflammatory models of demyelination, including experimental autoimmune encephalomyelitis, and both cuprizone- and global cerebral ischemia-induced demyelination. Preclinical studies suggest that quetiapine may exert these effects by stimulating proliferation and maturation of oligodendrocytes, releasing neurotrophic factors, increasing antioxidant defences, scavenging for free radicals, and inhibiting activated microglia, astrocytes, and T lymphocytes. Additionally, quetiapine may be beneficial for psychiatric and nonpsychiatric symptoms of MS including depression, anxiety, insomnia, and possibly even pain. These data indicate that clinical trials are justified to determine the safety, tolerability, and efficacy of quetiapine fumarate in MS.

Impairment of fragile X mental retardation protein-metabotropic glutamate receptor 5 signaling and its downstream cognates ras-related C3 botulinum toxin substrate 1, amyloid beta A4 precursor protein, striatal-enriched protein tyrosine phosphatase, and homer 1, in autism: a postmortem study in cerebellar vermis and superior frontal cortex

Background

Candidate genes associated with idiopathic forms of autism overlap with other disorders including fragile X syndrome. Our laboratory has previously shown reduction in fragile X mental retardation protein (FMRP) and increase in metabotropic glutamate receptor 5 (mGluR5) in cerebellar vermis and superior frontal cortex (BA9) of individuals with autism.

Methods

In the current study we have investigated expression of four targets of FMRP and mGluR5 signaling - homer 1, amyloid beta A4 precursor protein (APP), ras-related C3 botulinum toxin substrate 1 (RAC1), and striatal-enriched protein tyrosine phosphatase (STEP) - in the cerebellar vermis and superior frontal cortex (BA9) via SDS-PAGE and western blotting. Data were analyzed based on stratification with respect to age (children and adolescents vs. adults), anatomic region of the brain (BA9 vs. cerebellar vermis), and impact of medications (children and adolescents on medications (n = 4) vs. total children and adolescents (n = 12); adults on medications (n = 6) vs. total adults (n = 12)).

Results

There were significant increases in RAC1, APP 120 kDa and APP 80 kDa proteins in BA9 of children with autism vs. healthy controls. None of the same proteins were significantly affected in cerebellar vermis of children with autism. In BA9 of adults with autism there were significant increases in RAC1 and STEP 46 kDa and a significant decrease in homer 1 vs. controls. In the vermis of adult subjects with autism, RAC1 was significantly increased while APP 120, STEP 66 kDa, STEP 27 kDa, and homer 1 were significantly decreased when compared with healthy controls. No changes were observed in vermis of children with autism. There was a significant effect of anticonvulsant use on STEP 46 kDa/β-actin and a potential effect on homer 1/NSE, in BA9 of adults with autism. However, no other significant confound effects were observed in this study.

Conclusions

Our findings provide further evidence of abnormalities in FMRP and mGluR5 signaling partners in brains of individuals with autism and open the door to potential targeted treatments which could help ameliorate the symptoms of autism.

Improving myelin/oligodendrocyte-related dysfunction: a new mechanism of antipsychotics in the treatment of schizophrenia?

Schizophrenia is a severe psychiatric disorder with complex clinical manifestations and its aetiological factors remain unclear. During the past decade, the oligodendrocyte-related myelin dysfunction was proposed as a hypothesis for schizophrenia, supported initially by a series of neuroimaging studies and genetic evidence. Recently, the effects of antipsychotics on myelination and oligodendroglial lineage development and their underlying molecular mechanisms were evaluated. Data from those studies suggest that the antipsychotics-resulting improvement in myelin/oligodendrocyte-related dysfunction may contribute, at least in part, to their therapeutic effect on schizophrenia. Importantly, these findings may provide the basis for a new insight into the therapeutic strategy by targeting the oligodendroglia lineage cells against schizophrenia.

Neuregulin-1 exerts protective effects against neurotoxicities induced by C-terminal fragments of APP via ErbB4 receptor

Neuregulin-1 (NRG1) plays important roles in the development and plasticity of the brain, and it is also reported to have potent neuroprotective properties. We previously reported that NRG1 has neuroprotective actions against Swedish amyloid precursor protein-induced neurotoxicity. In addition to the amyloid beta peptide, other metabolites of amyloid precursor protein (APP) such as the C-terminal fragments of APP (APP-CTs) have been reported to possess cytotoxic effects in neuronal cells. In this study, we investigated whether NRG1 exerts neuroprotective effects against APP-CTs and attempted to determine its neuroprotective mechanisms. NRG1 attenuated the neurotoxicities induced by the expression of APP-CTs in neuronal cells. NRG1 also reduced the accumulation of reactive oxygen species and attenuated mitochondrial membrane potential loss induced by APP-CTs. In addition, NRG1 upregulated the expression of the anti-apoptotic protein Bcl-2. This effect was blocked by the inhibition of ErbB4, a key NRG1 receptor. Taken together, these results demonstrate the neuroprotective potential of NRG1 in Alzheimer's disease.

Effect of atypical antipsychotics on fetal growth: is the placenta involved?

There is currently considerable uncertainty regarding prescribing practices for pregnant women with severe and persistent psychiatric disorders. The physician and the mother have to balance the risks of untreated psychiatric illness against the potential fetal toxicity associated with pharmacological exposure. This is especially true for women taking atypical antipsychotics. Although these drugs have limited evidence for teratological risk, there are reports of altered fetal growth, both increased and decreased, with maternal atypical antipsychotic use. These effects may be mediated through changes in the maternal metabolism which in turn impacts placental function. However, the presence of receptors targeted by atypical antipsychotics in cell lineages present in the placenta suggests that these drugs can also have direct effects on placental function and development. The signaling pathways involved in linking the effects of atypical antipsychotics to placental dysfunction, ultimately resulting in altered fetal growth, remain elusive. This paper focuses on some possible pathways which may link atypical antipsychotics to placental dysfunction.

Neuroprotection of paliperidone on SH-SY5Y cells against β-amyloid peptide(25-35), N-methyl-4-phenylpyridinium ion, and hydrogen peroxide-induced cell death

RATIONALE

Antipsychotic drugs (APDs) were widely used in treating schizophrenia. Some APDs were reported to have neuroprotective effects against neurotoxicants in the cell level.

OBJECTIVES

Thus, one typical APD (haloperidol) and three atypical APDs (paliperidone, olanzapine, and risperidone) were tested whether they provide neuroprotection against stressor-induced cell death of SH-SY5Y.

METHODS

Hydrogen peroxide, N-methyl-4-phenylpyridinium ion, and β-amyloid peptide were used to treat cells with or without preconditioning by APDs; cell survival and indicators of oxidative stress were measured, respectively.

RESULTS

Paliperidone has the lowest baseline cytotoxicity compared with other APDs at 24 h; in addition, the paliperidone group showed a better survival than the other APD groups (P < 0.05). In stressor challenging, with a fixed concentration of stressors, olanzapine provided the best neuroprotection at 100 μM against Aβ(25-35) and MPP(+) (P < 0.05). In contrast, paliperidone works finely at low concentrations (10 and 50 μM) against Aβ(25-35) and MPP(+) and solely protected SH-SY5Y from hydrogen peroxide. At 100 μM, paliperidone completely diminished cell reduction induced by different stressors, regardless of their dosages. Paliperidone was demonstrated with a higher oxidative stress-scavenging properties than other APDs in several aspects, such as generated bulk glutathione, low HNE, and protein carbonyl productions. Contradictorily, olanzapine, at 24 h, also enhanced HNE and protein carbonyl productions, which may underlie its induced cytotoxicity.

CONCLUSIONS

Different APDs exhibit variations against different stressors. Paliperidone might be useful not only in alleviating oxidative stress induced by Aβ(25-35) and MPP(+) but also in providing neuroprotection against hydrogen peroxide.

The genotoxic potentials of some atypical antipsychotic drugs on human lymphocytes

Olanzapine (OLZ), risperidone (RPD) and quetiapine (QTP) are atypical antipsychotic drugs and are commonly used for the treatments of schizophrenia and bipolar disorders. However, recent reports indicated that these drugs could exhibit toxic effects on nervous and cardiovascular systems. To our best knowledge, there are scarce data considering the genotoxic damage potentials of OLZ, RPD and QTP on human lymphocyte culture system. Therefore, in this study, the genotoxic potentials of OLZ, RPD and QTP (0–400 mg/L) have been evaluated in human whole blood cultures (WBCs; n = 4). The single cell gel electrophoresis (SCGE) and micronucleus (MN) assays were applied to estimate the DNA damage. The results of the present study indicated that the tested antipsychotic drug did not induce genotoxicity. In fact, the mean values of the total scores of cells showing DNA damage (for SCGE assay) and MN/1000 cell were not found significantly different from the control values ( p > 0.05). However, the application of the highest drug concentrations (250 mg/L and above) caused the sterility in lymphocyte cultures. It is concluded that the tested three different atypical antipsychotic drugs can be used safely, but it is necessary to consider the cytotoxic effects that are likely to appear depending on the doses exposed.

Sulforaphane protects SK-N-SH cells against antipsychotic-induced oxidative stress

Adverse reactions to antipsychotic drugs (APs) have been attributed to oxidative stress. Sulforaphane (SF) is a potent antioxidant that protects against dopaminergic cell death. We examined the protective properties of SF against AP-induced oxidative stress in dopaminergic neuroblastoma cells. Human neuroblastoma SK-N-SH cells were treated with SF (0.5-5 μM), and 24 h later, haloperidol, risperidone or paliperidone (100 μM) was administered, either alone or in combination with dopamine (100 μM). To determine the antioxidant properties of SF, quinone oxidoreductase (NQO1) activity, glutathione S-transferase activity, and glutathione (GSH) levels were determined. Oxidative stress was measured by the increase in thiobarbituric acid reactive substances (TBARS) and in protein-bound quinones. Cell viability was also assessed. SF treatment increased GSH levels and induced NQO1 activity in SK-N-SH cells. Haloperidol was the only AP that increased TBARS when administered alone. When cells were cocultured with a drug in combination with dopamine, all three APs increased TBARS and protein-bound quinones and also induced neurotoxicity. In all the experimental conditions, 5 μM SF attenuated the accumulation of TBARS and protein-bound quinones and increased cell survival rates. Our results indicate that SF increases GSH levels and induces NQO1 activity and the removal of electrophilic quinones and radical oxygen species. Furthermore, SF could provide protective effects against AP-induced toxicity in dopaminergic cells.

Effects of antipsychotics and vitamin C on the formation of reactive oxygen species

There is evidence that reactive oxygen species (ROS) are involved in the pathophysiology of psychiatric disorders such as schizophrenia. Indirect biochemical alterations of ROS formation have been shown for patients treated with antipsychotics as well as for untreated patients. Only one study measured directly the ROS formation after treatment with antipsychotics by using electron spin resonance spectroscopy. The aim of the present examination was to demonstrate the effects of haloperidol, clozapine and olanzapine in concentrations of 18, 90 and 180 μg/mL on the formation of ROS in the whole blood of rats by using electron spin resonance spectroscopy after incubation for 30 min. To test the protective capacity of vitamin C we incubated the highest concentration of each drug with vitamin C (1 mM). Under all treatment conditions, olanzapine led to a significantly higher formation of ROS compared with control conditions, whereas in the cases of haloperidol and clozapine the two higher concentrations induced a significantly enhanced formation of ROS. Vitamin C reduced the ROS production of all drugs tested and for haloperidol and clozapine the level of significance was reached. Our study demonstrated that antipsychotics induce the formation of ROS in the whole blood of rats, which can be reduced by the application of vitamin C.

Lipid peroxidation in patients with schizophrenia

AIMS

There is evidence that dysregulation of free radicals metabolism associated with abnormal activities of antioxidative enzymes in schizophrenia can lead to lipid peroxidation in plasma, erythrocytes, blood platelets and cerebrospinal fluid. Injury to neurons in schizophrenia may affect their function, i.e. membrane transport, impairment of energy production in mitochondria, changes in membrane phospholipid composition, alteration of receptors and transporters as well as neurotransmission. The purpose of the present study was to assess the total antioxidant capacity (TAC) and lipid peroxidation (expressed as the level of thiobarbituric acid reactive substances [TBARS]) in plasma from schizophrenic patients taking olanzapine or risperidone. The level of TBARS estimated according to the Rice-Evans method and TAC ([ABTS; 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization assay]) in plasma from schizophrenic patients (DSM-IV criteria for schizophrenia, n = 30, age 18-36) taking olanzapine or risperidone and from healthy volunteers (n = 30) were measured.

METHODS

The level of TBARS in plasma from healthy volunteers after incubation with olanzapine or risperidone was also estimated.

RESULTS

Significantly lower plasma TAC (P < 0.05) and significantly increased level of TBARS (P < 0.001) in schizophrenic patients were observed. The in vitro study showed that after olanzapine or risperidone (at final concentrations corresponding to doses used in acute episodes of schizophrenia treatment) no changes of plasma lipid peroxidation were found (P > 0.05). The obtained results indicate that the pro-oxidant disturbances occur in schizophrenic patients (acute episode) taking stable doses of olanzapine or risperidone.

CONCLUSION

It seems that second-generation antipsychotics (olanzapine and risperidone) are not responsible for increase of plasma lipid peroxidation.

Oxidative damage to RNA but not DNA in the hippocampus of patients with major mental illness

BACKGROUND

Oxidative damage in the central nervous system is increasingly recognized as an important pathological process in many diseases. Previously, our laboratory found that oxidative damage to lipids and proteins was increased in postmortem brain tissue from patients with bipolar disorder and schizophrenia. In the current study, we analyzed oxidative damage to nucleic acids in the CA1, CA3 and dentate gyrus regions of postmortem hippocampus tissue from patients with bipolar disorder, schizophrenia and major depression.

METHODS

We examined oxidative damage to nucleic acids by performing immunohistochemistry with a monoclonal antibody that recognizes both 8-hydroxy-guanosine in RNA and 8-hydroxy-2'-deoxyguanosine in DNA.

RESULTS

We found that the amount of oxidative damage to nucleic acids was elevated in the CA1, CA3 and dentate gyrus regions of the hippocampus among patients with bipolar disorder, schizophrenia and major depressive disorder. This damage was predominantly in the cytoplasm, suggesting that the damage was primarily to RNA. Compared with oxidative damage in control samples, the magnitude of damage was high in patients with schizophrenia, modest in patients with bipolar disorder and lower in patients with major depression.

LIMITATIONS

The interpretation of our results is limited by a number of factors, including the retrospective review of patient history, the relatively small sample size and the inclusion of patients who had substance abuse and were undergoing various drug treatments at the time of death.

CONCLUSION

Our results suggest that oxidative damage to RNA, rather than to DNA, occurs in vulnerable neurons of the brain in patients with major mental illness and may contribute to the pathology of these disorders. The magnitude of RNA oxidative damage may be associated with the severity of mental illness.

Haloperidol promotes proliferation but inhibits differentiation in rat oligodendrocyte progenitor cell culturesThis paper is one of a selection of papers published in this special issue entitled “Second International Symposium on Recent Advances in Basic, Clinical, and Social Medicine” and has undergone the Journal's usual peer review process

Haloperidol is a commonly used, typical, antipsychotic drug (APD) that acts strongly against positive symptoms, but has fewer therapeutic effects on, or may even aggravate, negative symptoms and cognitive deficits in patients with schizophrenia. Loss of oligodendrocytes has been suggested as a factor associated with the negative symptoms of schizophrenia. Recent study shows that chronic haloperidol treatment induced down-regulation of oligodendrocyte-related genes in certain brain regions of mouse. In this study, we used primary oligodendrocyte progenitor cell cultures from 1- to 3-day-postnatal rats to investigate the direct effects of haloperidol on the proliferation and differentiation of oligodendrocyte progenitor cells. Our results showed that (i) haloperidol (0–10.0 µmol·L–1) facilitated the proliferation of oligodendrocyte progenitor cells, (ii) chronic haloperidol (0.5 µmol·L–1) treatment decreased the number of myelin basic protein positive oligodendrocytes and reduced the oligodendrocytes cells possessing myelin-like membranes, resulting in inhibition of the terminal differentiation of oligodendrocytes, and (iii) D3 receptor mRNA was detected in oligodendrocyte progenitor cells, and haloperidol treatment induced a down-regulation of D3 receptor mRNA. These results suggest that the typical antipsychotic drug haloperidol affects the development of oligodendrocyte progenitor cells, and that D3 receptor down regulation may be involved. Our observations provide new insight into possible cellular mechanisms responsible for the side effects of typical antipsychotic drugs and support the concept that abnormality of oligodendrocytes may be involved in the pathogenesis of schizophrenia.