Decreased levels of dopamine D3 receptor mRNA in schizophrenic and bipolar patients

Risperidone Decreases Expression of Serotonin Receptor-2A (5-HT2A) and Serotonin Transporter (SERT) but Not Dopamine Receptors and Dopamine Transporter (DAT) in PBMCs from Patients with Schizophrenia

Dopamine and serotonin receptors and transporters play an essential role in the pathophysiology of schizophrenia; changes in their expression have been reported in neurons and leukocytes. Each antipsychotic induces a unique pattern in leukocyte function and phenotype. However, the use of polytherapy to treat schizophrenia makes it challenging to determine the specific effects of risperidone on peripheral blood mononuclear cells (PBMCs). The aim of this study was to evaluate the changes in the expression of D3, D5, DAT, 5-HT2A, and SERT in PBMCs from healthy volunteers (HV), drug-naive patients with schizophrenia (PWS), drug-free PWS, and PWS treated with risperidone for up to 40 weeks using quantitative PCR. Our study revealed elevated mRNA levels of D3, DAT, 5-HT2A, and SERT in unmedicated PWS. Treatment with risperidone led to a reduction only in the expression of 5-HT2A and SERT. Furthermore, we observed a moderate correlation between 5-HT2A expression and the positive and negative syndrome scale (PANSS), as well as SERT expression and PANSS scale. We also found a moderate correlation between 5-HT2A and SERT expression and the positive subscale. The duration of risperidone consumption had a significant negative correlation with the expression of 5-HT2A and SERT. Our study introduces the measurement of 5-HT2A and SERT expression in PBMCs as a useful parameter for assessing the response to risperidone in PWS.

Interaction of Brain-Derived Neurotrophic Factor with the Effects of Chronic Methamphetamine on Prepulse Inhibition in Mice Is Independent of Dopamine D3 Receptors

The aim of the present study was to gain a better understanding of the role of brain-derived neurotrophic factor (BDNF) and dopamine D3 receptors in the effects of chronic methamphetamine (METH) on prepulse inhibition (PPI), an endophenotype of psychosis. We compared the effect of a three-week adolescent METH treatment protocol on the regulation of PPI in wildtype mice, BDNF heterozygous mice (HET), D3 receptor knockout mice (D3KO), and double-mutant mice (DM) with both BDNF heterozygosity and D3 receptor knockout. Chronic METH induced disruption of PPI regulation in male mice with BDNF haploinsufficiency (HET and DM), independent of D3 receptor knockout. Specifically, these mice showed reduced baseline PPI, as well as attenuated disruption of PPI induced by acute treatment with the dopamine receptor agonist, apomorphine (APO), or the glutamate NMDA receptor antagonist, MK-801. In contrast, there were no effects of BDNF heterozygosity or D3 knockout on PPI regulation in female mice. Chronic METH pretreatment induced the expected locomotor hyperactivity sensitisation, where female HET and DM mice also showed endogenous sensitisation. Differential sex-specific effects of genotype and METH pretreatment were observed on dopamine receptor and dopamine transporter gene expression in the striatum and frontal cortex. Taken together, these results show a significant involvement of BDNF in the long-term effects of METH on PPI, particularly in male mice, but these effects appear independent of D3 receptors. The role of this receptor in psychosis endophenotypes therefore remains unclear.

Dopamine, Immunity, and Disease

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

BDNF Therapeutic Mechanisms in Neuropsychiatric Disorders

Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the adult brain and functions as both a primary neurotrophic signal and a neuromodulator. It serves essential roles in neuronal development, maintenance, transmission, and plasticity, thereby influencing aging, cognition, and behavior. Accumulating evidence associates reduced central and peripheral BDNF levels with various neuropsychiatric disorders, supporting its potential utilization as a biomarker of central pathologies. Subsequently, extensive research has been conducted to evaluate restoring, or otherwise augmenting, BDNF transmission as a potential therapeutic approach. Promising results were indeed observed for genetic BDNF upregulation or exogenous administration using a multitude of murine models of neurological and psychiatric diseases. However, varying mechanisms have been proposed to underlie the observed therapeutic effects, and many findings indicate the engagement of disease-specific and other non-specific mechanisms. This is because BDNF essentially affects all aspects of neuronal cellular function through tropomyosin receptor kinase B (TrkB) receptor signaling, the disruptions of which vary between brain regions across different pathologies leading to diversified consequences on cognition and behavior. Herein, we review the neurophysiology of BDNF transmission and signaling and classify the converging and diverging molecular mechanisms underlying its therapeutic potentials in neuropsychiatric disorders. These include neuroprotection, synaptic maintenance, immunomodulation, plasticity facilitation, secondary neuromodulation, and preservation of neurovascular unit integrity and cellular viability. Lastly, we discuss several findings suggesting BDNF as a common mediator of the therapeutic actions of centrally acting pharmacological agents used in the treatment of neurological and psychiatric illness.

Potential biomarkers of addiction identified by real-time PCR in human peripheral blood lymphocytes: a narrative review

Addiction-related neurobiological factors could be considered as potential biomarkers. The concentration of peripheral biomarkers in tissues like blood lymphocytes may mirror their brain levels. This review is focused on the mRNA expression of potential addiction biomarkers in human peripheral blood lymphocytes (PBLs). PubMed, EMBASE, Web of Science, Scopus and Google Scholar were searched using the keywords 'addiction', 'biomarker', 'peripheral blood lymphocyte', 'gene expression' and 'real-time PCR'. The results showed the alterations in the regulation of genes such as dopamine receptors, opioid receptors, NMDA receptors, cannabinoid receptors, α-synuclein, DYN, MAO-A, FosB and orexin-A as PBLs biomarkers in addiction stages. Such variations could also be found during abstinence and relapse. PBLs biomarkers may help in drug development and have clinical implications.

Peripheral Blood-Based Gene Expression Studies in Schizophrenia: A Systematic Review

Schizophrenia is a disorder that is characterized by delusions, hallucinations, disorganized speech or behavior, and socio-occupational impairment. The duration of observation and variability in symptoms can make the accurate diagnosis difficult. Identification of biomarkers for schizophrenia (SCZ) can help in early diagnosis, ascertaining the diagnosis, and development of effective treatment strategies. Here we review peripheral blood-based gene expression studies for identification of gene expression biomarkers for SCZ. A literature search was carried out in PubMed and Web of Science databases for blood-based gene expression studies in SCZ. A list of differentially expressed genes (DEGs) was compiled and analyzed for overlap with genetic markers, differences based on drug status of the participants, functional enrichment, and for effect of antipsychotics. This literature survey identified 61 gene expression studies. Seventeen out of these studies were based on expression microarrays. A comparative analysis of the DEGs (n = 227) from microarray studies revealed differences between drug-naive and drug-treated SCZ participants. We found that of the 227 DEGs, 11 genes (ACOT7, AGO2, DISC1, LDB1, RUNX3, SIGIRR, SLC18A1, NRG1, CHRNB2, PRKAB2, and ZNF74) also showed genetic and epigenetic changes associated with SCZ. Functional enrichment analysis of the DEGs revealed dysregulation of proline and 4-hydroxyproline metabolism. Also, arginine and proline metabolism was the most functionally enriched pathway for SCZ in our analysis. Follow-up studies identified effect of antipsychotic treatment on peripheral blood gene expression. Of the 27 genes compiled from the follow-up studies AKT1, DISC1, HP, and EIF2D had no effect on their expression status as a result of antipsychotic treatment. Despite the differences in the nature of the study, ethnicity of the population, and the gene expression analysis method used, we identified several coherent observations. An overlap, though limited, of genetic, epigenetic and gene expression changes supports interplay of genetic and environmental factors in SCZ. The studies validate the use of blood as a surrogate tissue for biomarker analysis. We conclude that well-designed cohort studies across diverse populations, use of high-throughput sequencing technology, and use of artificial intelligence (AI) based computational analysis will significantly improve our understanding and diagnostic capabilities for this complex disorder.

The role of dopamine receptors in lymphocytes and their changes in schizophrenia

Dopamine and its 5 receptors, which are grouped into two families (D1-like and D2-like), modulate functions at a systemic level in both the central nervous system and periphery. The central nervous system and the immune system are the main adaptive systems, which participate in a continuous and functional crosstalk to guarantee homeostasis. On binding to its 5 dopamine receptors, dopamine acts as a co-regulator of the immune system, contributing to the interaction of the central nervous system and inflammatory events and as a source of communication between the different immune cells. Dopaminergic perturbations in the central nervous system are observed in several neurological and psychiatric disorders. Schizophrenia is one of the most common mental disorders with a poorly understood pathoaetiology that includes genetic and environmental components that promote alterations in the dopaminergic system. Interestingly, abnormalities in dopamine receptors expression in lymphocytes of schizophrenia patients have been reported, often significantly correlating with the severity of the psychotic illness. Here, we review the current literature regarding the dopaminergic system in human lymphocytes and its alterations in schizophrenia.

1.

The existence of DA in the bloodstream suggests the presence of dopaminergic components that modulate functions at a systemic level; therefore, its effects are not limited to the CNS and the signalling in the neuronal dopaminergic system should be independent from that of the peripheral systems.

2.

The effects by DA-mediated activation of different DRs on immune cells show different sensitivities to DA, but binding profiles of DA on T cells are similar to those in neuronal membranes, suggesting receptors act similarly to those found in neurons.

3.

All DRs are expressed on the LYM membrane. However, more detailed information is required on the expression patterns of DR in immune cells in healthy conditions and in pathologies.

4.

DA has been observed to influence LYM functions acting in a variety of important processes, like cytokine secretion, cell adhesion, chemotaxis, and cytotoxicity.

5.

In human LYM, DA on D1-like receptors decreases oxidative metabolism and apoptosis, activates the selective secretion of IL-10 and TNFα, and facilitates NK cells. In contrast, most of the immunostimulatory DA effects on LYM depend on stimulation of D2-like receptors including activation, proliferation, differentiation, and suppression of NK cells.

6.

To date, an altered expression or signalling of neurotransmitter receptors is observed in immune cells during psychiatric disorders and, consequently, these cells also markedly respond to antipsychotics.

7.

Numerous technologies have been used in search of biomarkers for SCZ. However, after a century of studying SCZ their application in psychiatry remains rare and there are currently no validated biomarkers for the diagnosis and prognosis of patients with SCZ or the prediction of treatment efficacy.

Expression of Dopamine D1-4 and Serotonin 5-HT1A-3A Receptors in Blood Mononuclear Cells in Schizophrenia

Introduction: The aim of this study was to determine the mRNA expression profile of dopamine D₁, D₂, D₃, D₄ and serotonin 5-HT_1A, 5-HT_2A, and 5-HT_3A receptors in peripheral blood mononuclear cells (PBMCs) in schizophrenia and the in vitro effect of antipsychotics on the expression of these receptors in PBMCs of healthy subjects. Materials and Methods: Twenty-seven patients with schizophrenia and 29 healthy controls were recruited for the study. All study subjects underwent thorough clinical assessment, including anthropometric and body composition measurements. The expression of mRNA for dopamine D_1-4 and serotonin 5-HT_1A-3A receptors was measured using quantitative RT-PCR in peripheral blood mononuclear cells. In vitro mRNA and protein expression of these receptors was measured using quantitative RT-PCR and Western Blotting in PBMCs cultured with quetiapine, haloperidol, aripiprazole, risperidone, olanzapine or clozapine at IC₅₀, half of IC₅₀, and one-quarter of IC₅₀ concentrations. Results: The key finding was that the schizophrenia group demonstrated significantly higher mRNA expression of D₁, D₂ and D₄ receptors (p < 0.001), and significantly lower mRNA expression of 5-HT_3A receptors (p < 0.01). After adjusting for smoking, the mRNA expression of D₁ lost its significance, while that of D₃, 5-HT_1A, 5-HT_2A became significant (all three were lower in the schizophrenia group). These receptors also demonstrated different ratios of mRNA expression in the schizophrenia group. The in vitro experiments showed that high concentrations of antipsychotics influenced the mRNA and protein expression of all studied receptors. Conclusion: Schizophrenia patients display a distinctive pattern of dopamine and serotonin receptor mRNA expression in blood mononuclear cells. This expression is little affected by antipsychotic treatment and it may therefore serve as a useful diagnostic biomarker for schizophrenia.

Altered dopamine D3 receptor gene expression in MAM model of schizophrenia is reversed by peripubertal cannabidiol treatment

Gestational methylazoxymethanol acetate (MAM) treatment produces offspring with adult phenotype relevant to schizophrenia, including positive- and negative-like symptoms, cognitive deficits, dopaminergic dysfunction, structural and functional abnormalities. Here we show that adult rats prenatally treated with MAM at gestational day 17 display significant increase in dopamine D3 receptor (D3) mRNA expression in prefrontal cortex (PFC), hippocampus and nucleus accumbens, accompanied by increased expression of dopamine D2 receptor (D2) mRNA exclusively in the PFC. Furthermore, a significant change in the blood perfusion at the level of the circle of Willis and hippocampus, paralleled by the enlargement of lateral ventricles, was also detected by magnetic resonance imaging (MRI) techniques. Peripubertal treatment with the non-euphoric phytocannabinoid cannabidiol (30 mg/kg) from postnatal day (PND) 19 to PND 39 was able to reverse in MAM exposed rats: i) the up-regulation of the dopamine D3 receptor mRNA (only partially prevented by haloperidol 0.6 mg/kg/day); and ii) the regional blood flow changes in MAM exposed rats. Molecular modelling predicted that cannabidiol could bind preferentially to dopamine D3 receptor, where it may act as a partial agonist according to conformation of ionic-lock, which is highly conserved in GPCRs. In summary, our results demonstrate that the mRNA expression of both dopamine D2 and D3 receptors is altered in the MAM model; however only the transcript levels of D3 are affected by cannabidiol treatment, likely suggesting that this gene might not only contribute to the schizophrenia symptoms but also represent an unexplored target for the antipsychotic activity of cannabidiol.

Maternal immune activation is associated with a lower number of dopamine receptor 3-expressing granulocytes with no alterations in cocaine reward, resistance to extinction or cue-induced reinstatement

There is evidence for increased rates of drug use among schizophrenic patients. However, the causality in this relationship remains unclear. In the present work, we use a maternal immune activation model to test whether animals at high risk of developing a schizophrenia-like condition are more prone to acquire cocaine self-administration, show enhanced sensitivity to the reinforcing actions of cocaine or if they are resistant to extinction or vulnerable to relapse. Also, given that D3 and CB2 receptor expression in immune cells is altered in patients with schizophrenia, we examined the populations of immune cells expressing these receptors. Pregnant rats were daily injected with lipopolysaccharide (LPS) (2 mg/kg s.c.) or saline during pregnancy, and we tested prepulse inhibition -PPI- in the offspring. After this, one group of rats was submitted to cocaine self-administration (0.5 mg/kg) under fixed and progressive ratio schedules, dose-response testing, extinction and cue-induced drug-seeking. Another group was sacrificed to study the immune blood cells by flow cytometry. While rats born to LPS-treated mothers showed impaired PPI, there were no differences in cocaine self-administration acquisition, responsiveness to dose shifts, extinction or cue-induced reinstatement. Finally, there were fewer D3R⁺ granulocytes in the LPS-offspring and an exciting trend for CB2R⁺ lymphocytes to be more abundant in LPS-exposed rats. Our results indicate that the higher prevalence of cocaine abuse among people with schizophrenia is not due to a pre-existing pathology and suggest that D3R⁺ granulocytes and possibly CB2R⁺ lymphocytes could be potential biomarkers of schizophrenia.

Coadministration of lithium and celecoxib attenuates the behavioral alterations and inflammatory processes induced by amphetamine in an animal model of mania

The present study evaluated the effects of the coadministration of lithium (Li) and Cel on inflammatory parameters in an animal model of mania induced by dextroamphetamine (D-amph). It was used Wistar rats 60 days old (250-350 g). The animals (n = 10 per group) received D-amph (2 mg/kg) or saline solution of NaCl 0.9% (Sal) intraperitoneally once a day for 14 days. From day eight until 14, the animals from the D-amph and Sal groups received Li (24 mg/kg), Cel (20 mg/kg), Li + Cel or water via gavage. Behavioral analyses were performed using the open-field test. The levels of IL-1β, IL-4, IL-10, and TNF-α were evaluated. The administration of D-amph induced hyperactivity in the rats, as well increased the IL-4, IL-10, and TNF-α levels in the serum, frontal cortex, and striatum of rats compared to those of the controls, and treatment with Li plus Cel reversed these alterations. In general, the administration of Li or Cel per se did not have effects on the behavioral and biochemical parameters. However, the treatment with Cel per se decreased only the IL-10 levels in the serum of animals. Besides, the treatment with Li or Cel decreased the IL-4 levels in the serum and reversed the effects of D-amph on this parameter in the frontal cortex. The treatment with Li reversed the effects of D-amph on the TNF-α levels in all tissues evaluated, and the administration of Cel reversed this alteration only in the striatum. It can be observed that treatment with Li plus Cel was more effective against damages caused by D-amph when compared to the administration of both treatments per se, suggesting that the coadministration can be more effective to treat BD rather than Li or Cel itself. The treatment with Li plus Cel was effective against the inflammation induced by D-amph.

Expression of NMDA receptor subunits in human blood lymphocytes: A peripheral biomarker in online computer game addiction

Background and aims Repeated performance of some behaviors such as playing computer games could result in addiction. The NMDA receptor is critically involved in the development of behavioral and drug addictions. It has been claimed that the expression level of neurotransmitter receptors in the brain may be reflected in peripheral blood lymphocytes (PBLs). Methods Here, using a real-time PCR method, we have investigated the mRNA expression of GluN2A, GluN2D, GluN3A, and GluN3B subunits of the NMDA receptor in PBLs of male online computer game addicts (n = 25) in comparison with normal subjects (n = 26). Results Expression levels of GluN2A, GluN2D, and GluN3B subunits were not statistically different between game addicts and the control group. However, the mRNA expression of the GluN3A subunit was downregulated in PBLs of game addicts. Discussion and conclusions Transcriptional levels of GluN2A and GluN2D subunits in online computer game addicts are similar to our previously reported data of opioid addiction and are not different from the control group. However, unlike our earlier finding of drug addiction, the mRNA expression levels of GluN3A and GluN3B subunits in PBLs of game addicts are reduced and unchanged, respectively, compared with control subjects. It seems that the downregulated state of the GluN3A subunit of NMDA receptor in online computer game addicts is a finding that deserves more studies in the future to see whether it can serve as a peripheral biomarker in addiction studies, where the researcher wants to rule out the confusing effects of abused drugs.

Association study of BDNF and DRD3 genes with alcohol use disorder in Schizophrenia

Alcohol use disorder (AUD) is a leading risk factor of disease burden in the world. It is also commonly comorbid with over 20% of schizophrenia patients. The brain-derived neurotrophic factor (BDNF) and dopamine D3 receptor (DRD3) have been implicated in alcohol drinking behaviour. Previous genetic studies of the BDNF and DRD3 genes produced mixed findings; however, only one study investigated two BDNF genetic markers with alcohol dependence in schizophrenia patients. We investigated 15 single-nucleotide polymorphisms (SNPs) in DRD3 and four SNPs in BDNF for possible association with alcohol abuse or dependence in schizophrenia patients of European ancestry (N = 195). The patients were assessed for the occurrence of alcohol abuse or alcohol dependence using the Structured Clinical Interview for DSM-IV Axis I Disorders, Patient Edition (SCID-I/P). We found the BDNF Val66Met to be associated with alcohol dependence (p = 0.004). We also found haplotypes across BDNF to be nominally associated with alcohol dependence. Analyses of DRD3 markers and haplotypes yielded mostly negative findings. Our findings support a role of the BDNF gene in alcohol dependence in schizophrenia patients. Larger samples are required to confirm our findings, particularly those of BDNF haplotypes.

An Integrative Computational Approach to Evaluate Genetic Markers for Bipolar Disorder

Studies to date have reported hundreds of genes connected to bipolar disorder (BP). However, many studies identifying candidate genes have lacked replication, and their results have, at times, been inconsistent with one another. This paper, therefore, offers a computational workflow that can curate and evaluate BP-related genetic data. Our method integrated large-scale literature data and gene expression data that were acquired from both postmortem human brain regions (BP case/control: 45/50) and peripheral blood mononuclear cells (BP case/control: 193/593). To assess the pathogenic profiles of candidate genes, we conducted Pathway Enrichment, Sub-Network Enrichment, and Gene-Gene Interaction analyses, with 4 metrics proposed and validated for each gene. Our approach developed a scalable BP genetic database (BP_GD), including BP related genes, drugs, pathways, diseases and supporting references. The 4 metrics successfully identified frequently-studied BP genes (e.g. GRIN2A, DRD1, DRD2, HTR2A, CACNA1C, TH, BDNF, SLC6A3, P2RX7, DRD3, and DRD4) and also highlighted several recently reported BP genes (e.g. GRIK5, GRM1 and CACNA1A). The computational biology approach and the BP database developed in this study could contribute to a better understanding of the current stage of BP genetic research and assist further studies in the field.

Theranostic Biomarkers for Schizophrenia

Schizophrenia is a highly heritable, chronic, severe, disabling neurodevelopmental brain disorder with a heterogeneous genetic and neurobiological background, which is still poorly understood. To allow better diagnostic procedures and therapeutic strategies in schizophrenia patients, use of easy accessible biomarkers is suggested. The most frequently used biomarkers in schizophrenia are those associated with the neuroimmune and neuroendocrine system, metabolism, different neurotransmitter systems and neurotrophic factors. However, there are still no validated and reliable biomarkers in clinical use for schizophrenia. This review will address potential biomarkers in schizophrenia. It will discuss biomarkers in schizophrenia and propose the use of specific blood-based panels that will include a set of markers associated with immune processes, metabolic disorders, and neuroendocrine/neurotrophin/neurotransmitter alterations. The combination of different markers, or complex multi-marker panels, might help in the discrimination of patients with different underlying pathologies and in the better classification of the more homogenous groups. Therefore, the development of the diagnostic, prognostic and theranostic biomarkers is an urgent and an unmet need in psychiatry, with the aim of improving diagnosis, therapy monitoring, prediction of treatment outcome and focus on the personal medicine approach in order to improve the quality of life in patients with schizophrenia and decrease health costs worldwide.

Immunomodulatory Effects Mediated by Dopamine

Dopamine (DA), a neurotransmitter in the central nervous system (CNS), has modulatory functions at the systemic level. The peripheral and central nervous systems have independent dopaminergic system (DAS) that share mechanisms and molecular machinery. In the past century, experimental evidence has accumulated on the proteins knowledge that is involved in the synthesis, reuptake, and transportation of DA in leukocytes and the differential expression of the D1-like (D1R and D5R) and D2-like receptors (D2R, D3R, and D4R). The expression of these components depends on the state of cellular activation and the concentration and time of exposure to DA. Receptors that are expressed in leukocytes are linked to signaling pathways that are mediated by changes in cAMP concentration, which in turn triggers changes in phenotype and cellular function. According to the leukocyte lineage, the effects of DA are associated with such processes as respiratory burst, cytokine and antibody secretion, chemotaxis, apoptosis, and cytotoxicity. In clinical conditions such as schizophrenia, Parkinson disease, Tourette syndrome, and multiple sclerosis (MS), there are evident alterations during immune responses in leukocytes, in which changes in DA receptor density have been observed. Several groups have proposed that these findings are useful in establishing clinical status and clinical markers.

Biomarkers in schizophrenia: A focus on blood based diagnostics and theranostics

Identifying biomarkers that can be used as diagnostics or predictors of treatment response (theranostics) in people with schizophrenia (Sz) will be an important step towards being able to provide personalized treatment. Findings from the studies in brain tissue have not yet been translated into biomarkers that are practical in clinical use because brain biopsies are not acceptable and neuroimaging techniques are expensive and the results are inconclusive. Thus, in recent years, there has been search for blood-based biomarkers for Sz as a valid alternative. Although there are some encouraging preliminary data to support the notion of peripheral biomarkers for Sz, it must be acknowledged that Sz is a complex and heterogeneous disorder which needs to be further dissected into subtype using biological based and clinical markers. The scope of this review is to critically examine published blood-based biomarker of Sz, focusing on possible uses for diagnosis, treatment response, or their relationship with schizophrenia-associated phenotype. We sorted the studies into six categories which include: (1) brain-derived neurotrophic factor; (2) inflammation and immune function; (3) neurochemistry; (4) oxidative stress response and metabolism; (5) epigenetics and microRNA; and (6) transcriptome and proteome studies. This review also summarized the molecules which have been conclusively reported as potential blood-based biomarkers for Sz in different blood cell types. Finally, we further discusses the pitfall of current blood-based studies and suggest that a prediction model-based, Sz specific, blood oriented study design as well as standardize blood collection conditions would be useful for Sz biomarker development.

The mRNA Expression Status of Dopamine Receptor D2, Dopamine Receptor D3 and DARPP-32 in T Lymphocytes of Patients with Early Psychosis

Peripheral blood lymphocytes are an attractive tool because there is accumulating evidence indicating that lymphocytes may be utilized as a biomarker in the field of psychiatric study as they could reveal the condition of cells distributed in the brain. Here, we measured the mRNA expression status of dopamine receptor D2 (DRD2), DRD3, and dopamine and cyclic adenosine 3',5'-monophosphate regulated phosphoprotein-32 (DARPP-32) in T lymphocytes of patients with early psychosis by quantitative real-time polymerase chain reaction (q-PCR) and explored the relationships between their mRNA levels and the psychopathological status of patients. The present study demonstrated that the mRNA expression levels of DRD3 in T lymphocytes were significantly different among controls, and in patients with psychotic disorder not otherwise specified (NOS) and schizophrenia/schizophreniform disorder. However, no significant differences in mRNA expression levels of DRD2 and DARPP-32 were found among the three groups. We found a significant positive correlation between the DRD2 mRNA level and the score of the excited factor of the Positive and Negative Syndrome Scale (PANSS) in patients with schizophrenia/schizophreniform disorder. These findings suggest that DRD3 mRNA levels may serve as a potential diagnostic biomarker differentiating patients with early psychosis from controls.

Adaptive Immunity in Schizophrenia: Functional Implications of T Cells in the Etiology, Course and Treatment

Schizophrenia is a severe and highly complex neurodevelopmental disorder with an unknown etiopathology. Recently, immunopathogenesis has emerged as one of the most compelling etiological models of schizophrenia. Over the past few years considerable research has been devoted to the role of innate immune responses in schizophrenia. The findings of such studies have helped to conceptualize schizophrenia as a chronic low-grade inflammatory disorder. Although the contribution of adaptive immune responses has also been emphasized, however, the precise role of T cells in the underlying neurobiological pathways of schizophrenia is yet to be ascertained comprehensively. T cells have the ability to infiltrate brain and mediate neuro-immune cross-talk. Conversely, the central nervous system and the neurotransmitters are capable of regulating the immune system. Neurotransmitter like dopamine, implicated widely in schizophrenia risk and progression can modulate the proliferation, trafficking and functions of T cells. Within brain, T cells activate microglia, induce production of pro-inflammatory cytokines as well as reactive oxygen species and subsequently lead to neuroinflammation. Importantly, such processes contribute to neuronal injury/death and are gradually being implicated as mediators of neuroprogressive changes in schizophrenia. Antipsychotic drugs, commonly used to treat schizophrenia are also known to affect adaptive immune system; interfere with the differentiation and functions of T cells. This understanding suggests a pivotal role of T cells in the etiology, course and treatment of schizophrenia and forms the basis of this review.

Leukocyte Gene Expression in Patients with Medication Refractory Depression before and after Treatment with ECT or Isoflurane Anesthesia: A Pilot Study

Objective. To evaluate leukocyte gene expression for 9 selected genes (mRNAs) as biological markers in patients with medication refractory depression before and after treatment with ECT or isoflurane anesthesia (ISO). Methods. In a substudy of a nonrandomized open-label trial comparing effects of ECT to ISO therapy, blood samples were obtained before and after treatment from 22 patients with refractory depression, and leukocyte mRNA was assessed by quantitative PCR. Patients' mRNAs were also compared to 17 healthy controls. Results. Relative to controls, patients before treatment showed significantly higher IL10 and DBI and lower ADRA2A and ASIC3 mRNA (P < 0.025). Both ECT and ISO induced significant decreases after treatment in 4 genes: IL10, NR3C1, DRD4, and Sult1A1. After treatment, patients' DBI, ASIC3, and ADRA2A mRNA remained dysregulated. Conclusion. Significant differences from controls and/or significant changes after ECT or ISO treatment were observed for 7 of the 9 mRNAs studied. Decreased expression of 4 genes after effective treatment with either ECT or ISO suggests possible overlap of underlying mechanisms. Three genes showing dysregulation before and after treatment may be trait-like biomarkers of medication refractory depression. Gene expression for these patients has the potential to facilitate diagnosis, clarify pathophysiology, and identify potential biomarkers for treatment effects.

Fenproporex increases locomotor activity and alters energy metabolism, and mood stabilizers reverse these changes: a proposal for a new animal model of mania

Fenproporex (Fen) is converted in vivo into amphetamine, which is used to induce mania-like behaviors in animals. In the present study, we intend to present a new animal model of mania. In order to prove through face, construct, and predictive validities, we evaluated behavioral parameters (locomotor activity, stereotypy activity, and fecal boli amount) and brain energy metabolism (enzymes citrate synthase; malate dehydrogenase; succinate dehydrogenase; complexes I, II, II-III, and IV of the mitochondrial respiratory chain; and creatine kinase) in rats submitted to acute and chronic administration of fenproporex, treated with lithium (Li) and valproate (VPA). The administration of Fen increased locomotor activity and decreased the activity of Krebs cycle enzymes, mitochondrial respiratory chain complexes, and creatine kinase, in most brain structures evaluated. In addition, treatment with mood stabilizers prevented and reversed this effect. Our results are consistent with the literature that demonstrates behavioral changes and mitochondrial dysfunction caused by psychostimulants. These findings suggest that chronic administration of Fen may be a potential animal model of mania.

State-related alterations of gene expression in bipolar disorder: a systematic review

OBJECTIVE

Alterations in gene expression in bipolar disorder have been found in numerous studies. It is unclear whether such alterations are related to specific mood states. As a biphasic disorder, mood state-related alterations in gene expression have the potential to point to markers of disease activity, and trait-related alterations might indicate vulnerability pathways. This review therefore evaluated the evidence for whether gene expression in bipolar disorder is state or trait related.

METHODS

A systematic review, using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline for reporting systematic reviews, based on comprehensive database searches for studies on gene expression in patients with bipolar disorder in specific mood states, was conducted. We searched Medline, Embase, PsycINFO, and The Cochrane Library, supplemented by manually searching reference lists from retrieved publications.

RESULTS

A total of 17 studies were included, comprising 565 patients and 418 control individuals. Six studies evaluated intraindividual alterations in gene expression across mood states. Two of five studies found evidence of intraindividual alterations in gene expression between a depressed state and a euthymic state. No studies evaluated intraindividual differences in gene expression between a manic state and a euthymic state, while only one case study evaluated differences between a manic state and a depressed state, finding altered expression in seven genes. No study investigated intraindividual variations in gene expression between a euthymic state and multiple states of various polarities (depressive, manic, hypomanic). Intraindividual alterations in expression of the same genes were not investigated across studies. Only one gene (the brain-derived neurotrophic factor gene; BDNF) was investigated across multiple studies, showing no alteration between bipolar disorder patients and control individuals.

CONCLUSIONS

There is evidence of some genes exhibiting state-related alterations in expression in bipolar disorder; however, this finding is limited by the lack of replication across studies. Further prospective studies are warranted, measuring gene expression in various affective phases, allowing for assessment of intraindividual differences.

The dopaminergic system in peripheral blood lymphocytes: from physiology to pharmacology and potential applications to neuropsychiatric disorders

Besides its action on the nervous system, dopamine (DA) plays a role on neural-immune interactions. Here we review the current evidence on the dopaminergic system in human peripheral blood lymphocytes (PBL). PBL synthesize DA through the tyrosine-hydroxylase/DOPA-decarboxylase pathway, and express DA receptors and DA transporter (DAT) on their plasma membrane. Stimulation of DA receptors on PBL membrane contributes to modulate the development and initiation of immune responses under physiological conditions and in immune system pathologies such as autoimmunity or immunodeficiency.

The characterization of DA system in PBL gave rise to a further line of research investigating the feasibility of PBL as a cellular model for studying DA derangement in neuropsychiatric disorders. Several reports showed changes of the expression of DAT and/or DA receptors in PBL from patients suffering from several neuropsychiatric disorders, in particular parkinsonian syndromes, schizophrenia and drug- or alcohol-abuse. Despite some methodological and theoretical limitations, these findings suggest that PBL may prove a cellular tool with which to identify the derangement of DA transmission in neuropsychiatric diseases, as well as to monitor the effects of pharmacological treatments.

Effects of lithium and valproate on oxidative stress and behavioral changes induced by administration of m-AMPH

In the last years our research group has studied and validated the animal model of mania induced by dextroamphetamine (d-AMPH). Considering the lack of animal models of mania reported in the literature; this study evaluated the possibilities to validate the animal model induced by methamphetamine (m-AMPH). Then, we evaluated the effects of lithium (Li), valproate (VPA) on the behavior and parameters of oxidative damage in rat brain after administration of m-AMPH. In the prevention treatment, Wistar rats were pretreated with Li, VPA or saline (Sal) for 14 days, and then, between days 8 and 14, rats were treated with m-AMPH (1, 0.5 or 0.25 mg/kg) or Sal. In the reversal treatment, rats were first given m-AMPH (0.25 mg/kg) or Sal. Locomotor behavior was assessed using the open-field task and parameters of oxidative damage were measured in brain structures. Our results show that the hyperactivity was prevented and reverted by Li and VPA only when m-AMPH was administered in the dose of 0.25mg/kg. In addition, the m-AMPH in all doses administrated induced oxidative damage in both structures tested in two models. Li and VPA reversed and prevented this impairment, however in a way dependent of cerebral area, the dose of m-AMPH and technique.

Psychotropic drug effects on gene transcriptomics relevant to Parkinson's disease

OBJECTIVES

Psychotropic drugs are widely prescribed in Parkinson's disease (PD) without regard to their pathobiological effects, and these drugs affect the transcription of a large number of genes. Effects of these drugs on PD risk gene transcription were therefore surveyed.

METHODS

Results summarize a comprehensive survey of psychotropic effects on messenger ribonucleic acid (mRNA) expression evident in published data for 70 genes linked to PD risk.

RESULTS

Psychotropic drugs can meaningfully affect PD risk gene mRNA transcription, including antipsychotics (upregulate dopamine receptors D2 and D3 (DRD2, DRD3); downregulate low-density lipoprotein receptor-related protein 8 (LRP8), ubiquitin carboxyl-terminal esterase L1 (UCHL1, also known as PARK5)), haloperidol (upregulates DRD3, parkin (PRKN, also known as PARK2), DRD2; downregulates brain-derived neurotrophic factor (BDNF)), risperidone (upregulates monoamine oxidase B (MAOB), DRD2), olanzapine (upregulates transmembrane protein 163 (TMEM163), BDNF, glutathione S-transferase mu 1 (GSTM1), MAOB, DRD2, solute carrier organic anion transporter family, member 3A1 (SLCO3A1)), aripiprazole (upregulates DRD2), quetiapine, paliperidone, lurasidone, carbamazepine, and many antidepressants (upregulate BDNF), lithium and bupropion (downregulate BDNF), amitriptyline (upregulates DRD3, DRD2), imipramine (upregulates BDNF, DRD3, DRD2), desipramine (upregulates BDNF, DRD3), and fluoxetine (upregulates acid beta-glucosidase (GBA), coiled-coil domain containing 62 (CCDC62), BDNF, DRD3, UCHL1, unc-13 homolog B (UNC13B), and perhaps huntingtin interacting protein 1 related (HIP1R); downregulates microtubule-associated protein tau (MAPT), methylcrotonoyl-coenzyme A carboxylase I (MCCC1), GSTM1, 28kDa calbindin 1 (CALB1)). Fluoxetine effects on BDNF and UCHL1 in GEO Profiles were statistically robust.

CONCLUSIONS

This report provides an initial summary and framework to understand the potential impact of psychotropic drugs on PD-relevant genes. Antipsychotics and serotoninergic antidepressants may potentially attenuate PD risk, and lithium and bupropion may augment risk, through MAPT, GBA, CCDC62, HIP1R, BDNF, and DRD2 transcription, with MAPT, GBA, and CCDC62 being strongly associated with PD risk in recent meta-analyses. Limitations of these findings and a research agenda to better relate them to the nigrostriatum and PD are discussed.

Disease-specific expression of the serotonin-receptor 5-HT(2C) in natural killer cells in Alzheimer's dementia

Alzheimer's dementia (AD) is a degenerative brain disorder characterized mainly by cholinergic failure, but other neuro-transmitters are also deficient especially at late stages of the disease. Misfolded β-amyloid peptide has been identified as a causative agent, however inflammatory changes also play a pivotal role. Even though the most prominent pathology is seen in the cognitive functions, specific abnormalities of the central nervous system (CNS) are also reflected in the periphery, particularly in the immune responses of the body. The aim of this study was to characterize the dopaminergic and serotonergic systems in AD, which are also markedly disrupted along with the hallmark acetyl-choline dysfunction. Peripheral blood mono-nuclear cells (PBMCs) from demented patients were judged against comparison groups including individuals with late-onset depression (LOD), as well as non-demented and non-depressed subjects. Cellular sub-populations were evaluated by mono-clonal antibodies against various cell surface receptors: CD4/CD8 (T-lymphocytes), CD19 (B-lymphocytes), CD14 (monocytes), and CD56 (natural-killer (NK)-cells). The expressions of dopamine D(3) and D(4), as well as serotonin 5-HT(1A), 5-HT(2A), 5-HT(2B) and 5-HT(2C) were also assessed. There were no significant differences among the study groups with respect to the frequency of the cellular sub-types, however a unique profound increase in 5-HT(2C) receptor exclusively in NK-cells was observed in AD. The disease-specific expression of 5-HT(2C), as well as the NK-cell cyto-toxicity, has been linked with cognitive derangement in dementia. These changes not only corroborate the existence of bi-directional communication between the immune system and the CNS, but also elucidate the role of inflammatory activity in AD pathology, and may serve as potential biomarkers for less invasive and early diagnostic purposes as well.

Increase in dopaminergic, but not serotoninergic, receptors in T-cells as a marker for schizophrenia severity

Schizophrenia is characterized by a slow deteriorating mental illness. Although the pathophysiology mechanisms are not fully understood, different studies have suggested a role for the immune system in the pathogenesis of schizophrenia. To date, an altered expression or signaling of neurotransmitters receptors is observed in immune cells during psychiatric disorders. In the present study, we investigated the expression of different serotonin and dopamine receptors in T-cells of schizophrenic and control patients. We used flow cytometry to determine the pattern of expression of dopamine (D2 and D4) and serotonine receptors (SR1A, SR1C, SR2A, SR2B), as well as serotonin transporter (ST), in T-cell subsets (CD4 and CD8). Expression of serotonin receptors and ST in T-cells of schizophrenic patients were not different from controls. However, the percentages of CD4+D4+ and CD8+D4+ were increased in schizophrenic patients as compared to controls. In addition, increased percentages of CD8+D2+ cells were also observed in schizophrenic patients, albeit this population revealed lower CD4+D2+ cells in comparison to controls. Interestingly, a relationship between clinical symptoms and immunological parameters was also observed. We showed that the Brief Psychiatric Rating Scale (BPRS), the Positive and Negative Syndrome Scale (PANSS) and the Abnormal Involuntary Movement Scale (AIMS) were positively related to CD8+D2+ cells, though AIMS was inversely related to CD4+D4+ cells. In conclusion, the alteration in the pattern of cell population and molecules expressed by them might serve as a promising biomarker for diagnosis of schizophrenia.

The clinical implications of cognitive impairment and allostatic load in bipolar disorder

BACKGROUND

Allostatic load (AL) relates to the neural and bodily "wear and tear" that emerge in the context of chronic stress. This paper aims to provide clinicians with a comprehensive overview of the role of AL in patophysiology of bipolar disorder (BD) and its practical implications.

METHODS

PubMed searches were conducted on English-language articles published from 1970 to June 2011 using the search terms allostatic load, oxidative stress, staging, and bipolar disorder cross-referenced with cognitive impairment, comorbidity, mediators, prevention.

RESULTS

Progressive neural and physical dysfunction consequent to mood episodes in BD can be construed as a cumulative state of AL. The concept of AL can help to reconcile cognitive impairment and increased rates of clinical comorbidities that occur over the course of cumulative BD episodes.

CONCLUSIONS

Data on transduction of psychosocial stress into the neurobiology of mood episodes converges to the concept of AL. Mood episodes prevention would not only alleviate emotional suffering, but also arrest the cycle of AL, cognitive decline, physical morbidities and, eventually, related mortality. These objectives can be achieved by focusing on effective prophylaxis from the first stages of the disorder, providing mood-stabilizing agents and standardized psychoeducation and, potentially, addressing cognitive deficits by the means of specific medication and neuropsychological interventions.

Biomarkers for antipsychotic therapies

Molecular biomarkers for antipsychotic treatments have been conceptually linked to the measurements of dopamine functions, mostly D(2) receptor occupancy, either by imaging using selective PET/SPECT radioactive tracers or by assessing plasma prolactin levels. A quest for novel biomarkers was recently proposed by various academic, health service, and industrial institutions driven by the need for better treatments of psychoses. In this review we conceptualize biomarkers within the Translational Medicine paradigm whose goal was to provide support to critical decision-making in drug discovery. At first we focused on biomarkers as outcome measure of clinical studies by searching into the database clinicaltrial.gov. The results were somewhat disappointing, showing that out of 1,659 antipsychotic trials only 18 used a biomarker as an outcome measure. Several of these trials targeted plasma lipids as sentinel marker for metabolic adverse effects associated with the use of atypical antipsychotics, while only few studies were aimed to new disease specific biological markers. As an example of a mechanistic biomarker, we described the work done to progress the novel class of glycine transporter inhibitors as putative treatment for negative symptoms of schizophrenia. We also review how large-scale multiplex biological assays were applied to samples from tissues of psychiatric patients, so to learn from changes of numerous analytes (metabolic products, lipids, proteins, RNA transcripts) about the substrates involved in the disease. We concluded that a stringent implementation of these techniques could contribute to the endophenotypic characterization of patients, helping in the identification of key biomarkers to drive personalized medicine and new treatment development.

Altered mRNA expression of monoaminergic candidate genes in the blood of children with attention deficit hyperactivity disorder and autism spectrum disorder

OBJECTIVES

In absence of objective clinical characteristics the identification of peripheral biomarkers in neuropsychiatric disorders is highly relevant for the diagnostic process and an individualized therapy. We analyzed mRNA-expression of monoaminergic candidate genes (DRD4, DRD5, TPH1) in peripheral tissue of patients with attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD), highly comorbid with ADHD, searching for possible molecular markers for these disorders.

METHODS

mRNA was obtained from children and adolescents with ADHD (n = 51) and ASD (n = 26), diagnosed according to ICD-10 criteria, as well as healthy controls (n = 39). mRNA expression was determined via quantitative realtime PCR (qRT-PCR) from whole blood cells.

RESULTS

The concentrations of DRD4-mRNA in the whole blood were significantly lower in ADHD and ASD children (19 of 26 comorbid with ADHD) compared to healthy controls. ASD patients revealed a significantly decreased DRD5 mRNA expression in comparison to the two other groups.

CONCLUSIONS

Alterations in mRNA expression patterns provide further evidence for a relevant effect of the respective candidate genes in the pathophysiology of ADHD. Given their potential as biomarkers mRNA expression patterns may be useful tools in (differential-) diagnostic procedures of ADHD and ASD. Future studies may determine the sensitivity and specificity of these putative biomarkers in larger samples including further neuropsychiatric diagnoses.

Converging evidence implicates the dopamine D3 receptor gene in vulnerability to schizophrenia

The dopamine D3 receptor has been implicated in the pathophysiology of schizophrenia (SZ). A glycine-to-serine polymorphism at codon 9 of the dopamine D3 receptor gene (DRD3), rs6280, has been widely studied for its association with SZ, but with conflicting results. Altered levels of DRD3 mRNA have also been reported in SZ compared with normal controls. Moreover, it has been suggested that DRD3 is subject to recent positive selection in European populations. To explore the potential role of DRD3 in SZ from these various aspects, we conducted a threefold study. First, we tested the genetic association of rs6280 with SZ in 685 SZ patients and 768 normal controls. Second, we examined DRD3 mRNA levels in peripheral leukocytes in a subset of 37 patients and 37 controls. Finally, we investigated the possible recent positive selection on DRD3 in an East Asian population. Consequently, we observed that the genotypic distribution of rs6280 was nominally associated with SZ (P = 0.045), with the ancestral CC genotype being significantly over-represented in SZ patients. DRD3 mRNA levels were significantly lower in patients than in controls (P = 5.91E-5). The derived C-allele of rs6280 might have been subject to recent positive selection (P < 0.001) in the East Asian population. Taken together, our results suggest that DRD3, a gene possibly under natural selection, might be involved in vulnerability to SZ in the Han Chinese population. These findings may further add to the body of data implicating DRD3 as a schizophrenia risk gene.

The first decade and beyond of transcriptional profiling in schizophrenia

Gene expression changes in brains of individuals with schizophrenia (SZ) have been hypothesized to reflect possible pathways related to pathophysiology and/or medication. Other factors having robust effects on gene expression profiling in brain and possibly influence the schizophrenia transcriptome such as age and pH are examined. Pathways of curated gene expression or gene correlation networks reported in SZ (white matter, apoptosis, neurogenesis, synaptic plasticity, glutamatergic and GABAergic neurotransmission, immune and stress-response, mitochondrial, and neurodevelopment) are not unique to SZ and have been associated with other psychiatric disorders. Suggestions going forward to improve the next decade of profiling: consider multiple brain regions that are carefully dissected, release large datasets from multiple brain regions in controls to better understand neurocircuitry, integrate genetics and gene expression, measure expression variants on genome wide level, peripheral biomarker studies, and analyze the transcriptome across a developmental series of brains. Gene expression, while an important feature of the genomic landscape, requires further systems biology to advance from control brains to a more precise definition of the schizophrenia interactome.

ECT in a patient with Parkinson's disease and schizophrenia, with dopamine transporter visualisation using 123I-ioflupane SPET

A 58-year old woman with chronic schizophrenia developed worsening parkinsonian symptoms over the previous 6 years, and was eventually diagnosed as having Parkinson's disease. Antipsychotics were stopped because they worsened these symptoms. Antiparkinsonian treatment led to a significant increase in delusions and behavioural disorganisation. The patient underwent electroconvulsive-therapy which improved both her psychiatric and motor symptoms. After treatment, 123I-Ioflupane uptake was mildly increased in the left caudate nucleus, but uptake in right caudate nucleus was lower than in a pretreatment scan.

Striatal structure and function in mood disorders: a comprehensive review

OBJECTIVES

  A large and diverse literature has implicated abnormalities of striatal structure and function in both unipolar and bipolar disorder. Recent functional imaging studies have greatly expanded this body of research. The aim of this review is to provide a comprehensive and critical appraisal of the relevant literature.

METHODS

  A total of 331 relevant articles were reviewed to develop an integrated overview of striatal function in mood disorders.

RESULTS

  There is compelling evidence from multiple studies that functional abnormalities of the striatum and greater corticostriatal circuitry exist in at least some forms of affective illness. The literature does not yet provide data to determine whether these aberrations represent primary pathology or they contribute directly to symptom expression. Finally, there is considerable evidence that bipolar disorder may be associated with striatal hyperactivity and some suggestion that unipolar illness may be associated with hypoactivation.

CONCLUSIONS

  Additional research investigating striatal function in affective disorders will be critical to the development of comprehensive models of the neurobiology of these conditions.

Association study of BDNF and DRD3 genes in schizophrenia diagnosis using matched case-control and family based study designs

Schizophrenia (SCZ) is a severe neuropsychiatric disorder with prominent genetic etiologic factors. The dopamine receptor DRD3 gene is a strong candidate in genetic studies of SCZ because of the dopamine hypothesis of SCZ and the selective expression of D(3) in areas of the limbic system implicated in the disease. We examined 15 single-nucleotide polymorphisms (SNPs) in DRD3 in our sample of European origin consisting of 95 small nuclear SCZ families and 167 case-control pairs. We also examined four BDNF SNPs in our samples because of evidence for BDNF regulation of DRD3 expression (Guillin et al., 2001). We found a nominally significant genotypic association with rs7633291 and allelic association with rs1025398 alleles. However, these observations did not survive correction for multiple testing. We did not find a statistically significant association with the other DRD3 and BDNF polymorphisms. Taken together, the results from the present study suggest that BDNF and DRD3 may not be involved in SCZ susceptibility.

Is the dopamine D3 receptor mRNA on blood lymphocytes help to for identification and subtyping of schizophrenia?

Schizophrenia is one of the neuropathological disorders, which are associated with dopamine and its receptors. In recent years, it has been shown that mRNA of D3, D4 and D5 dopamine receptor (DRD3, DRD4, DRD5) subtypes is expressed in human peripheral blood lymphocytes (PBL). A total 55 schizophrenic patients and 51 healthy subjects were included in the study to investigate the levels of DRD3 mRNA in PBL of schizophrenic patients and whether DRD3 mRNA level in PBL can serve as peripheral marker for schizophrenia. RNA was isolated from lymphocytes of both groups and reverse transcriptase polymerase chain reaction (RT-PCR) was performed for DRD3 mRNA. We found a significant difference in PBL DRD3 mRNA levels among schizophrenia subtypes (P=0.030) while no difference was detected between control subjects and schizophrenics. We concluded that the levels of DRD3 mRNA can help understanding and severity of clinical manifestations in schizophrenia.

Effects of mood stabilizers on mitochondrial respiratory chain activity in brain of rats treated with d-amphetamine

Bipolar disorder (BD) is a devastating major mental illness associated with high rates of suicide and work loss. There is an emerging body of data suggesting that bipolar disorder is associated with mitochondrial dysfunction. In this context, the present study aims to investigate the effects of mood stabilizers lithium (Li) and valproate (VPT) on mitochondrial respiratory chain activity in brain of rats undergoing treatment with the pro-manic agent d-AMPH d-amphetamine (d-AMPH). In the reversal treatment, Wistar rats were first given d-AMPH or saline for 14 days, and then, between days 8 and 14, rats were treated with Li, VPA or saline (Sal). In the prevention treatment, rats were pretreated with Li, VPA or Sal. Locomotor behavior was assessed using the open-field task and mitochondrial chain activity complexes I, II, III and IV were measured in brain structures (hippocampus, striatum and prefrontal). Li and VPA reversed and prevented d-AMPH-induced hyperactivity. In both experiments, d-AMPH inhibited mitochondrial respiratory chain activity in all analyzed structures. In the reversal treatment, VPA reversed d-AMPH-induced dysfunction in all brain regions analyzed. In the prevention experiment, the effects of Li and VPA on d-AMPH-induced mitochondrial dysfunction were dependent on the brain region analyzed. These findings suggested that dopamine can be an important link for the mitochondrial dysfunction seen in BD and, Li and VPA exert protective effects against this d-AMPH-induced mitochondrial dysfunction, but this effect varies depending on the brain region and the treatment regimen.

Temperamentsxgenes in bipolar I and bipolar II disorder patients

We found the main effects of harm avoidance temperament in predicting bipolar I and II, but the interaction between novelty seeking and Ser9Gly polymorphisms of dopamine D3 receptor gene was demonstrated in bipolar-I patients only. This study provided evidence that differences existed between BP-I and BPII in gene and temperament interactions.

(+)-UH 232, a partial agonist of the D3 dopamine receptors, attenuates cognitive effects of angiotensin IV and des-Phe(6)-angiotensin IV in rats

We have recently found that postsynaptic D3 dopamine (DA) receptors appear not to participate in the memory enhancing effects of the angiotensin AT4 receptor agonists angiotensin IV (Ang IV) and des-Phe(6)-Ang IV. In this study we evaluated role of the presynaptic DA D3 receptors in these effects. For that purpose effect of (+)-UH 232, a selective D3 DA receptors partial agonist preferring presynaptic sites, on the pro-cognitive action of intracerebroventricularly (icv) injected Ang IV and des-Phe(6)-Ang IV was examined. Male Wistar rats weighing 180-200 g were used. Both peptides given at the dose of 1 nmol facilitated recall of a passive avoidance (PA) behaviour, improved object recognition (OR), and increased apomorphine-induced stereotype behaviour. In the auxiliary tests performed to control for the unspecific influence of motor (open field, OF) and emotional ('plus' maze, PM) effects of our treatments on the results of the memory tests they had either no (OF) or negligible (PM) effects. Intraperitoneal pre-treatment of the animals with an ineffective on its own dose (1 mg/kg) of (+)-UH 232 abolished or markedly diminished effects of both peptides on PA and OR but did not influence enhancement of stereotypy caused by the peptides.

The dopamine D3 receptor (DRD3) gene and risk of schizophrenia: case-control studies and an updated meta-analysis

The dopamine D3 receptor (DRD3) has been suggested to be involved in the pathophysiology of schizophrenia. DRD3 has been tested for an association with schizophrenia, but with conflicting results. A recent meta-analysis suggested that the haplotype T-T-T-G for the SNPs rs7631540-rs1486012-rs2134655-rs963468 may confer protection against schizophrenia. However, almost all previous studies of the association between DRD3 and schizophrenia have been performed using a relatively small sample size and a limited number of markers. To assess whether DRD3 is implicated in vulnerability to schizophrenia, we conducted case-control association studies and performed an updated meta-analysis. In the first population (595 patients and 598 controls), we examined 16 genotyped single nucleotide polymorphisms (SNPs), including tagging SNPs selected from the HapMap database and SNPs detected through resequencing, as well as 58 imputed SNPs that are not directly genotyped. To confirm the results obtained, we genotyped the SNPs rs7631540-rs1486012-rs2134655-rs963468 in a second, independent population (2126 patients and 2228 controls). We also performed an updated meta-analysis of the haplotype, combining the results obtained in five populations, with a total sample size of 7551. No supportive evidence was obtained for an association between DRD3 and schizophrenia in our Japanese subjects. Our updated meta-analysis also failed to confirm the existence of a protective haplotype. To draw a definitive conclusion, further studies using larger samples and sufficient markers should be carried out in various ethnic populations.

The role of dopamine in bipolar disorder

OBJECTIVE

Despite effective pharmacological treatments for bipolar disorder, we still lack a comprehensive pathophysiological model of the illness. Recent neurobiological research has implicated a number of key brain regions and neuronal components in the behavioural and cognitive manifestations of bipolar disorder. Dopamine has previously been investigated in some depth in bipolar disorder, but of late has not been a primary focus of attention. This article examines the role of dopamine in bipolar disorder, incorporating recent advances into established models where possible.

METHODS

A critical evaluation of the literature was undertaken, including a review of behavioural, neurochemical, receptor, and imaging studies, as well as genetic studies focusing on dopamine receptors and related metabolic pathways. In addition, pharmacologic manipulation of the central dopaminergic pathways and comparisons with other disease states such as schizophrenia were considered, principally as a means of exploring the hypothesised models.

RESULTS

Multiple lines of evidence, including data from pharmacological interventions and structural and functional magnetic resonance imaging studies, suggest that the dopaminergic system may play a central role in bipolar disorder.

CONCLUSION

Future research into the pathophysiological mechanisms of bipolar disorder and the development of new treatments for bipolar disorder should focus on the dopaminergic system.

Can body mass index help predict outcome in patients with bipolar disorder?

OBJECTIVE

Several studies have reported higher prevalence of obesity in patients suffering from bipolar disorder (BD). To study the relation of elevated body mass index (BMI) in patients with BD more closely, we investigated differences in sociodemographic, clinical, and medical characteristics with respect to BMI, with the hypothesis that BMI is related to prognosis and outcome.

METHODS

We measured the BMI of 276 subjects of a tertiary care sample from the Maritime Bipolar Registry. Subjects were 16 to 83 years old, with psychiatric diagnoses of bipolar I disorder (n = 186), bipolar II disorder (n = 85), and BD not otherwise specified (n = 5). The registry included basic demographic data and details of the clinical presentation. We first examined the variables showing a significant association with BMI; subsequently, we modeled the relationship between BMI and psychiatric outcome using structural equation analysis.

RESULTS

The prevalence of obesity in our sample was 39.1%. We found higher BMI in subjects with a chronic course (p < 0.001) and longer duration of illness (p = 0.02), lower scores on the Global Assessment of Functioning Scale (p = 0.02), and on disability (p = 0.002). Overweight patients had more frequent comorbid subthreshold social (p = 0.02) and generalized anxiety disorders (p = 0.05), diabetes mellitus type II (p < 0.001), and hypertension (p = 0.001). Subjects who achieved complete remission of symptoms on lithium showed significantly lower BMI (p = 0.01).

CONCLUSIONS

Our findings suggest that BMI is associated with the prognosis and outcome of BD. Whether this association is causal remains to be determined.

Gene expression changes in normal haematopoietic cells

The complexity of the healthy haematopoietic system is immense, and as such, one must understand the biology driving normal haematopoietic expression profiles when designing experiments and interpreting expression data that involve normal cells. This article seeks to present an organised approach to the use and interpretation of gene profiling in normal haematopoiesis and broadly illustrates the challenges of selecting appropriate controls for high-throughput expression studies.

Dopamine receptor D3 genotype association with greater acute positive symptom remission with olanzapine therapy in predominately caucasian patients with chronic schizophrenia or schizoaffective disorder

OBJECTIVE

To test association of dopamine receptor D3 (DRD-3) gene polymorphisms with olanzapine response in genetic samples from a registration phase clinical trial.

METHODS

Eighty-eight acutely ill patients with schizophrenia or schizoaffective disorder were genotyped for ser-9-gly (rs6280) and 23 other polymorphisms within the DRD-3 gene. Allelic association of clinical response (mean baseline- to-endpoint reduction in Positive and Negative Syndrome Scale [PANSS] total and subscores) over 6 weeks of olanzapine treatment was assessed using repeated measures analysis of variance.

RESULTS

Ser-9-gly genotypes were associated with differences in PANSS total score improvement from baseline to 6 weeks (p = 0.021). This association was most notable for improvement in positive symptoms (p = 0.0001), with patients with gly/gly genotype significantly more responsive. More patients with the gly/gly genotype had greater positive symptom remission (endpoint rating of minimal or none on all PANSS positive items, 39.1%) compared with patients with gly/ser and ser/ser genotypes (13.8%; p = 0.033). DRD-3 polymorphisms in disequilibrium with ser-9-gly were also significantly associated with greater positive symptom improvement (p = 0.0009-0.021), and one not in complete linkage disequilibrium, with lesser improvement (p = 0.027).

CONCLUSIONS

Gly/gly DRD-3 genotype predicted statistically and clinically significantly better acute positive symptom reduction compared with other ser-9-gly genotypes in patients treated with olanzapine.

Calcineurin A gamma and B gene expressions in the whole blood in Japanese patients with schizophrenia

Calcineurin (CaN) has been regarded as a candidate gene for vulnerability of schizophrenia. Although CaN gene expression has been investigated with postmortem brain specimens or in association studies, little information is available about CaN gene expression levels in peripheral sources. We obtained whole blood samples from 16 patients with schizophrenia and 16 controls, and total RNA was extracted. CaN A gamma and CaN B genes were analyzed by quantitative RT-PCR. In the patient group, expression levels of both genes were correlated with psychopathology, as measured by the Brief Psychiatric Rating Scale (BPRS), and neuroleptic dose. No significant differences in CaN A gamma or CaN B gene expression were observed between patients with schizophrenia and normal controls. Linear regression analysis revealed that the CaN A gamma gene expression level was associated with the BPRS score but not with neuroleptic dose. Neither of the clinical variables was associated with the CaN B gene expression level. The results of this study suggest that the CaN A gamma gene may be an effective predictor of the progression of psychosis. The effect of medications on expression of CaN genes requires further study.

Multiple genes and factors associated with bipolar disorder converge on growth factor and stress activated kinase pathways controlling translation initiation: implications for oligodendrocyte viability

Famine and viral infection, as well as interferon therapy have been reported to increase the risk of developing bipolar disorder. In addition, almost 100 polymorphic genes have been associated with this disease. Several form most of the components of a phosphatidyl-inositol signalling/AKT1 survival pathway (PIK3C3, PIP5K2A, PLCG1, SYNJ1, IMPA2, AKT1, GSK3B, TCF4) which is activated by growth factors (BDNF, NRG1) and also by NMDA receptors (GRIN1, GRIN2A, GRIN2B). Various other protein products of genes associated with bipolar disorder either bind to or are affected by phosphatidyl-inositol phosphate products of this pathway (ADBRK2, HIP1R, KCNQ2, RGS4, WFS1), are associated with its constituent elements (BCR, DUSP6, FAT, GNAZ) or are downstream targets of this signalling cascade (DPYSL2, DRD3, GAD1, G6PD, GCH1, KCNQ2, NOS3, SLC6A3, SLC6A4, SST, TH, TIMELESS). A further pathway relates to endoplasmic reticulum-stress (HSPA5, XBP1), caused by problems in protein glycosylation (ALG9), growth factor receptor sorting (PIK3C3, HIP1R, SYBL1), or aberrant calcium homoeostasis (WFS1). Key processes relating to these pathways appear to be under circadian control (ARNTL, CLOCK, PER3, TIMELESS). DISC1 can also be linked to many of these pathways. The growth factor pathway promotes protein synthesis, while the endoplasmic reticulum stress pathway, and other stress pathways activated by viruses and cytokines (IL1B, TNF, Interferons), oxidative stress or starvation, all factors associated with bipolar disorder risk, shuts down protein synthesis via control of the EIF2 alpha and beta translation initiation complex. For unknown reasons, oligodendrocytes appear to be particularly prone to defects in the translation initiation complex (EIF2B) and the convergence of these environmental and genomic signalling pathways on this area might well explain their vulnerability in bipolar disorder.