A NOS-III haplotype that includes functional polymorphisms is associated with bipolar disorder

Uncovering associations between mental illness diagnosis, nitric oxide synthase gene variation, and peripheral nitric oxide concentration

Nitric oxide (NO) signalling has been implicated in the pathogenesis of several mental illnesses; however, its specific contribution remains unclear. We investigated whether peripheral NO concentration is associated with specific diagnoses, and whether there is a correlation with genetic variation in NO synthase (NOS) genes. We included 185 participants in the study; 52 healthy controls, 43 major depressive disorder (MDD) patients, 41 bipolar disorder (BPD) patients, and 49 schizophrenia (SCZ) patients. Clinical, genetic, and biochemical data were collected at admission to a psychiatric hospital and at discharge. Serum was used to quantify concentration of the stable NO metabolites nitrite and nitrate. Individuals were genotyped for the NOS1 exon 1f variable number of tandem repeats 1 (VNTR1) polymorphism, and single nucleotide polymorphisms (SNPs) in the NOS1, NOS1AP and NOS3 genes. At admission, SCZ patients were found to have significantly higher peripheral NO metabolite (NO_x-) concentrations compared to healthy controls, MDD and BPD patients. NOS1 exon 1f VNTR1 short allele carriers were found to have significantly increased NO_x- concentration. Moreover, this result was still significant in patients even at discharge. The data also revealed that patients who did not remit in their depressive symptoms had significantly increased NO_x- concentration compared to remitters at discharge, supported by the finding of a significant positive correlation between depression symptom severity and NO_x- concentration. Taken together, it is possible that elevated peripheral NO_x- concentration is associated with increased severity of psychopathology, potentially due to NOS1 exon1f VNTR1 genotype. Our results further implicate NO signalling in mental illness pathogenesis, supporting its possible use as a peripheral biomarker, and imply that NOS genotype may play a significant role in regulating peripheral NO_x- concentration.

Impact of Mood on Endothelial Function and Arterial Stiffness in Bipolar Disorder

Background

Previous research in bipolar disorder demonstrates greater than expected vascular dysfunction later in the course of illness, proportionate to the cumulative burden of mood symptoms. However, little is known about the effect of acute mood states on vascular function. Here we examine the relation between vascular function and mood state in individuals with bipolar disorder.

Method

This prospective study followed 40 individuals with bipolar disorder for up to 6 months. Participants were assessed for mood state and vascular function at baseline, 2 weeks, and 6 months. Mood state was determined using clinician-administered Montgomery-Åsberg Depression Rating Scale and Young Mania Rating Scale. Vascular function was assessed by flow-mediated dilation (FMD) of the brachial artery, forearm vascular resistance (FVR), and arterial stiffness.

Results

Participants had a mean age of 30.1 years and 75% were male. Primary outcome measures FMD and nitroglycerine-mediated dilation were not found to have statistically significant associations with depressive or manic symptoms. In unadjusted models, higher manic symptoms were significantly associated with increased FVR nitroprusside-mediated dilation and diastolic blood pressure. In adjusted models, higher depressive symptoms were significantly associated with increases in augmentation index adjusted for heart rate of 75 bpm, and higher manic symptoms remained associated with increases in diastolic blood pressure.

Conclusion

FMD may have limited sensitivity as a biomarker for measuring short-term effects of mood state. Longer-term prospective studies are needed to clarify the temporal relation between chronic mood symptoms and vascular function in bipolar disorder.

Leaky brain in neurological and psychiatric disorders: Drivers and consequences

BACKGROUND

The blood-brain barrier acts as a highly regulated interface; its dysfunction may exacerbate, and perhaps initiate, neurological and neuropsychiatric disorders.

METHODS

In this narrative review, focussing on redox, inflammatory and mitochondrial pathways and their effects on the blood-brain barrier, a model is proposed detailing mechanisms which might explain how increases in blood-brain barrier permeability occur and can be maintained with increasing inflammatory and oxidative and nitrosative stress being the initial drivers.

RESULTS

Peripheral inflammation, which is causatively implicated in the pathogenesis of major psychiatric disorders, is associated with elevated peripheral pro-inflammatory cytokines, which in turn cause increased blood-brain barrier permeability. Reactive oxygen species, such as superoxide radicals and hydrogen peroxide, and reactive nitrogen species, such as nitric oxide and peroxynitrite, play essential roles in normal brain capillary endothelial cell functioning; however, chronically elevated oxidative and nitrosative stress can lead to mitochondrial dysfunction and damage to the blood-brain barrier. Activated microglia, redox control of which is mediated by nitric oxide synthases and nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, secrete neurotoxic molecules such as reactive oxygen species, nitric oxide, prostaglandin, cyclooxygenase-2, quinolinic acid, several chemokines (including monocyte chemoattractant protein-1 [MCP-1], C-X-C motif chemokine ligand 1 [CXCL-1] and macrophage inflammatory protein 1α [MIP-1α]) and the pro-inflammatory cytokines interleukin-6, tumour necrosis factor-α and interleukin-1β, which can exert a detrimental effect on blood-brain barrier integrity and function. Similarly, reactive astrocytes produce neurotoxic molecules such as prostaglandin E2 and pro-inflammatory cytokines, which can cause a 'leaky brain'.

CONCLUSION

Chronic inflammatory and oxidative and nitrosative stress is associated with the development of a 'leaky gut'. The following evidence-based approaches, which address the leaky gut and blood-brain barrier dysfunction, are suggested as potential therapeutic interventions for neurological and neuropsychiatric disorders: melatonin, statins, probiotics containing Bifidobacteria and Lactobacilli, N-acetylcysteine, and prebiotics containing fructo-oligosaccharides and galacto-oligosaccharides.

Molecular profiling of reticular gigantocellularis neurons indicates that eNOS modulates environmentally dependent levels of arousal

Neurons of the medullary reticular nucleus gigantocellularis (NGC) and their targets have recently been a focus of research on mechanisms supporting generalized CNS arousal (GA) required for proper cognitive functions. Using the retro-TRAP method, we characterized transcripts enriched in NGC neurons which have projections to the thalamus. The unique expression and activation of the endothelial nitric oxide (eNOS) signaling pathway in these cells and their intimate connections with blood vessels indicate that these neurons exert direct neurovascular coupling. Production of nitric oxide (NO) within eNOS-positive NGC neurons increases after environmental perturbations, indicating a role for eNOS/NO in modulating environmentally appropriate levels of GA. Inhibition of NO production causes dysregulated behavioral arousal after exposure to environmental perturbation. Further, our findings suggest interpretations for associations between psychiatric disorders and mutations in the eNOS locus.

Pathologic role of nitrergic neurotransmission in mood disorders

Mood disorders are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although over the past 40 years the biogenic amine models have provided meaningful links with the clinical phenomena of, and the pharmacological treatments currently employed in, mood disorders, there is still a need to examine the contribution of other systems to the neurobiology and treatment of mood disorders. This article reviews the current literature describing the potential role of nitric oxide (NO) signaling in the pathophysiology and thereby the treatment of mood disorders. The hypothesis has arisen from several observations including (i) altered NO levels in patients with mood disorders; (ii) antidepressant effects of NO signaling blockers in both clinical and pre-clinical studies; (iii) interaction between conventional antidepressants/mood stabilizers and NO signaling modulators in several biochemical and behavioral studies; (iv) biochemical and physiological evidence of interaction between monoaminergic (serotonin, noradrenaline, and dopamine) system and NO signaling; (v) interaction between neurotrophic factors and NO signaling in mood regulation and neuroprotection; and finally (vi) a crucial role for NO signaling in the inflammatory processes involved in pathophysiology of mood disorders. These accumulating lines of evidence have provided a new insight into novel approaches for the treatment of mood disorders.

Neuronal nitric oxide synthase (NOS1) and its adaptor, NOS1AP, as a genetic risk factors for psychiatric disorders

Nitric oxide (NO) is a gaseous transmitter produced by nitric oxide synthases (NOSs). The neuronal isoform (NOS-I, encoded by NOS1) is the main source of NO in the central nervous system (CNS). Animal studies suggest that nitrinergic dysregulation may lead to behavioral abnormalities. Unfortunately, the large number of animal studies is not adequately reflected by publications concerning humans. These include post-mortem studies, determination of biomarkers, and genetic association studies. Here, we review the evidence for the role of NO in psychiatric disorders by focusing on the human NOS1 gene as well as biomarker studies. Owing to the complex regulation of NOS1 and the varying function of NOS-I in different brain regions, no simple, unidirectional association is expected. Rather, the 'where, when and how much' of NO formation is decisive. Present data, although still preliminary and partially conflicting, suggest that genetically driven reduced NO signaling in the prefrontal cortex is associated with schizophrenia and cognition. Both NOS1 and its interaction partner NOS1AP have a role therein. Also, reduced NOS1 expression in the striatum determined by a length polymorphism in a NOS1 promoter (NOS1 ex1f-VNTR) goes along with a variety of impulsive behaviors. An association of NOS1 with mood disorders, suggested by animal models, is less clear on the genetic level; however, NO metabolites in blood may serve as biomarkers for major depression and bipolar disorder. As the nitrinergic system comprises a relevant target for pharmacological interventions, further studies are warranted not only to elucidate the pathophysiology of mental disorders, but also to evaluate NO function as a biomarker.

Violent suicidal behaviour in bipolar disorder is associated with nitric oxide synthase 3 gene polymorphism

OBJECTIVE

Given the importance of nitric oxide system in oxidative stress, inflammation, neurotransmission and cerebrovascular tone regulation, we postulated its potential dysfunction in bipolar disorder (BD) and suicide. By simultaneously analysing variants of three isoforms of nitric oxide synthase (NOS) genes, we explored interindividual genetic liability to suicidal behaviour in BD.

METHOD

A total of 536 patients with BD (DSM-IV) and 160 healthy controls were genotyped for functionally relevant NOS1, NOS2 and NOS3 polymorphisms. History of suicidal behaviour and violent suicide attempt was documented for 511 patients with BD. Chi-squared test was used to perform genetic association analyses and logistic regression to test for gene-gene interactions.

RESULTS

NOS3 rs1799983 T homozygous state was associated with violent suicide attempts (26.4% vs. 10.8%, in patients and controls, P = 0.002, corrected P (Pc) = 0.004, OR: 2.96, 95% CI = 1.33-6.34), and this association was restricted to the early-onset BD subgroup (37.9% vs. 10.8%, in early-onset BD and controls, P = 0.0003, Pc = 0.0006 OR: 5.05, 95% CI: 1.95-12.45), while we found no association with BD per se and no gene-gene interactions.

CONCLUSION

Our results bring further evidence for the potential involvement of endothelial NOS gene variants in susceptibility to suicidal behaviour. Future exploration of this pathway on larger cohort of suicidal behaviour is warranted.

Multi-level biomarker analysis of nitric oxide synthase isoforms in bipolar disorder and adult ADHD

INTRODUCTION

Several studies have shown altered levels of nitric oxide (NO) and its stable metabolites (NOx (-)) in blood and cerebrospinal fluid of psychiatric patients. The aim of our study was to replicate previous findings and investigate the influence of the nitrinergic system in bipolar disorder and adult attention-deficit/hyperactivity disorder (aADHD) in particular.

METHODS

The concentrations of NO2 (-) and NO3 (-) in peripheral blood in a sample of aADHD, bipolar disorder (BPD) and controls were analysed. The sample was genotyped for a three marker haplotype in the NOS3 gene (rs2070744, rs1799983 and Intron 4 VNTR) and for genetic variants of the NOS1 gene (NOS1 ex 1c, NOS1 ex 1f). Finally, qRT PCR was performed.

RESULTS

We found significantly lower NOx (-) levels in BPD (p<0.001). rs2070744 T/T-carriers of the whole sample showed increased mRNA expression of NOS3 (p=0.05). Only in BPD an influence of rs2070744 was seen regarding NO metabolite levels; C/C carriers displayed lower NOx (-) levels (p=0.05).

CONCLUSION

We could replicate and extend previous findings showing altered NOx (-) levels in BPD and an influence of NOS3 rs2070744 on NOS3 expression and NOx (-) concentration. Together, these data point to a role of the nitrinergic pathway in BPD.

Role of NOS3 DNA variants in externalizing behavioral problems observed in childhood leukemia survivors

OBJECTIVE

Neuropsychological problems occurrence varies among childhood cancer survivors, and associated risk factors have not been fully deciphered. We wanted to study the role of genetic variants in behavioral problems in this population.

STUDY DESIGN

Behavioral problems in pediatric acute lymphoblastic leukemia patients (n=138) were investigated longitudinally, using the Child Behavior Checklist questionnaire and multilevel statistical modeling. Thirty-four candidate polymorphisms, related to anticancer drug effects, were investigated.

RESULTS

NOS3 gene functional polymorphisms showed significant association: patients homozygous for the minor allele at investigated loci showed decreased externalizing behavioral problems scores over time (t tests: T-786C n=69, P=0.003; G894T n=71, P=0.065). The effect was even more pronounced for individuals that are homozygous for the -786C844T haplotype (t test, n=69, P<0.001) and results were supported by multilevel modeling analyses (P<0.001). No such association was observed for internalizing behavioral problems.

CONCLUSION

NOS3 variants modulate externalizing problems individual trajectories, likely in relationship with glucocorticoid exposure.

Decreased NOS1 expression in the anterior cingulate cortex in depression

Decreased function of the anterior cingulate cortex (ACC) is crucially involved in the pathogenesis of depression. A key role of nitric oxide (NO) has also been proposed. We aimed to determine the NO content in the cerebrospinal fluid (CSF) and the expression of NO synthase (NOS) isoforms, that is, NOS1, NOS2, and NOS3 in the ACC in depression. In depressive patients, CSF-NOx levels (the levels of the NO metabolites nitrite and nitrate) were significantly decreased (P = 0.007), indicating a more general decrease of NO production in this disorder. This agreed with a trend toward lower NOS1-mRNA levels (P = 0.083) and a significant decrease of NOS1-immunoreactivity (ir) (P = 0.043) in ACC. In controls, there was a significant positive correlation between ACC-NOS1-ir cell densities and their CSF-NOx levels. Furthermore, both localization of NOS1 in pyramidal neurons that are known to be glutamatergic and co-localization between NOS1 and GABAergic neurons were observed in human ACC. The diminished ACC-NOS1 expression and decreased CSF-NOx levels may be involved in the alterations of ACC activity in depression, possibly by affecting glutamatergic and GABAergic neurotransmission.

Expression of monoamine transporters, nitric oxide synthase 3, and neurotrophin genes in antidepressant-stimulated astrocytes

BACKGROUND

There is increasing evidence that glial cells play a role in the pathomechanisms of mood disorders and the mode of action of antidepressant drugs.

METHODS

To examine whether there is a direct effect on the expression of different genes encoding proteins that have been implicated in the pathophysiology of affective disorders, primary astrocyte cell cultures from rats were treated with two different antidepressant drugs, imipramine and escitalopram, and the RNA expression of brain-derived neurotrophic factor (Bdnf), serotonin transporter (5Htt), dopamine transporter (Dat), and endothelial nitric oxide synthase (Nos3) was examined.

RESULTS

Stimulation of astroglial cell culture with imipramine, a tricyclic antidepressant, led to a significant increase of the Bdnf RNA level whereas treatment with escitalopram did not. In contrast, 5Htt was not differentially expressed after antidepressant treatment. Finally, neither Dat nor Nos3 RNA expression was detected in cultured astrocytes.

CONCLUSION

These data provide further evidence for a role of astroglial cells in the molecular mechanisms of action of antidepressants.

Genetic Association Analysis of NOS3 and Methamphetamine-Induced Psychosis Among Japanese

Endothelial nitric oxide synthase (NOS3) is one of the enzymes influencing nitric oxide (NO) function in the human brain. NO is a gaseous neurotransmitter that is involved in a variety of mechanisms in the central nervous system, such as N-methyl-D-aspartate receptor activation and oxidative stress. The evidence from animal pharmacological studies and postmortem studies supports an association between NO and psychotic disorders. Methamphetamine (METH) use disorder is a known psychotic disorder, and we therefore conducted a gene-based case-control study between tagging single nucleotide polymorphisms (SNPs) (rs2070744, rs1799983) in NOS3 and METH-induced psychosis in Japanese subjects (183 with METH-induced psychosis and 267 controls). Written informed consent was obtained from each subject. No significant association was found between any tagging SNP in NOS3 and METH-induced psychosis in the allele/genotype-wise or haplotype-wise analyses. In conclusion, we suggest that NOS3 might not contribute to the risk of METH-induced psychosis in the Japanese population.

Expression profiling in neuropsychiatric disorders: emphasis on glutamate receptors in bipolar disorder

Functional genomics and proteomics approaches are being employed to evaluate gene and encoded protein expression changes with the tacit goal to find novel targets for drug discovery. Genome-wide association studies (GWAS) have attempted to identify valid candidate genes through single nucleotide polymorphism (SNP) analysis. Furthermore, microarray analysis of gene expression in brain regions and discrete cell populations has enabled the simultaneous quantitative assessment of relevant genes. The ability to associate gene expression changes with neuropsychiatric disorders, including bipolar disorder (BP), and their response to therapeutic drugs provides a novel means for pharmacotherapeutic interventions. This review summarizes gene and pathway targets that have been identified in GWAS studies and expression profiling of human postmortem brain in BP, with an emphasis on glutamate receptors (GluRs). Although functional genomic assessment of BP is in its infancy, results to date point towards a dysregulation of GluRs that bear some similarity to schizophrenia (SZ), although the pattern is complex, and likely to be more complementary than overlapping. The importance of single population expression profiling of specific neurons and intrinsic circuits is emphasized, as this approach provides informative gene expression profile data that may be underappreciated in regional studies with admixed neuronal and non-neuronal cell types.

Three polymorphisms of the eNOS gene and plasma levels of metabolites of nitric oxide in depressed Japanese patients: a preliminary report

BACKGROUND

Depression is a risk factor for coronary heart disease. Nitric oxide (NO) plays an important role in both coronary heart disease and depression.

METHODS

Fifty-one inpatients and outpatients who met the Diagnostic and Statistical Manual of Mental Disorders--Fourth Edition criteria for major depressive disorder (MDD) in the university hospital of the University of Occupational and Environmental Health and 58 age-matched and sex-matched healthy controls enrolled in this study. We investigated the association between the three polymorphisms of the endothelial nitric oxide synthase (eNOS) gene (single-nucleotide polymorphism (SNP); rs2070744, rs1799983, variable number tandem repeat (VNTR) in intron 4) and scores on the Hamilton Rating Scale for Depression, plasma metabolites of NO (NO(x) ) or ankle brachial index in patients with MDD and healthy controls.

RESULTS

We did not find significant differences in the genotype distributions between patients with MDD and healthy volunteers. No associations were observed between any of the polymorphisms of the eNOS gene and the Hamilton Rating Scale for Depression or ankle brachial index in patients with MDD. However, plasma NO(x) level was significantly associated with a polymorphism of the eNOS gene (rs207044 and variable number tandem repeat in intron 4).

CONCLUSION

These results suggest that the direct association was not observed between the polymorphisms of the eNOS gene and the pathogenesis of depression.

Activation of Akt signaling in rat brain by intracerebroventricular injection of ouabain: a rat model for mania

Intracerebroventricular (ICV) injection of ouabain, a specific Na-K ATPase inhibitor, induces behavioral changes in rats resembling the manic phenotypes of bipolar disorder. The binding of ouabain to the Na-K ATPase affects signal events in vitro including Akt, a possible molecular target of mood disorders. However, the effects of ouabain on Akt in the brain need further clarification. In this study, we investigated changes in the phosphorylation state of Akt in the rat brain after ICV injection of ouabain. Consistent with our previous report, the locomotor activity of rats within 30 min after ouabain ICV injection changed according to the dose with higher doses of ouabain, 0.5 and 1 mM, inducing significant hyperactivity. In addition, ouabain administration induced a dose-dependent increase in the immunoreactivity of p-Akt (Ser473) in the frontal cortex, striatum, and hippocampus after 30 min, and reached statistical significance with 1mM of ouabain. Phosphorylation of GSK-3beta (Ser9), FOXO1 (Ser256), and eNOS (Ser1177), which are downstream molecules of Akt, was also increased in a dose-dependent manner within the same brain regions. Moreover, hyperactivity was seen for 8h after a single 1mM injection of ouabain and increased phosphorylation of Akt (Ser473), GSK-3beta (Ser9), FOXO1 (Ser256), and eNOS (Ser1177) was also observed in the cortex, striatum, and hippocampus. Thus, intrabrain injection of ouabain induces activation of Akt signaling accompanied by hyperactivity, suggesting the possible role of Akt in ouabain rat model of mania.

Hyperactivity, startle reactivity and cell-proliferation deficits are resistant to chronic lithium treatment in adult Nr2e1(frc/frc) mice

The NR2E1 region on Chromosome 6q21-22 has been repeatedly linked to bipolar disorder (BP) and NR2E1 has been associated with BP, and more specifically bipolar I disorder (BPI). In addition, patient sequencing has shown an enrichment of rare candidate-regulatory variants. Interestingly, mice carrying either spontaneous (Nr2e1(frc) ) or targeted (Tlx(-) ) deletions of Nr2e1 (here collectively known as Nr2e1-null) show similar neurological and behavioral anomalies, including hypoplasia of the cerebrum, reduced neural stem cell proliferation, extreme aggression and deficits in fear conditioning; these are the traits that have been observed in some patients with BP. Thus, NR2E1 is a positional and functional candidate for a role in BP. However, no Nr2e1-null mice have been fully evaluated for behaviors used to model BP in rodents or pharmacological responses to drugs effective in treating BP symptoms. In this study we examine Nr2e1(frc/frc) mice, homozygous for the spontaneous deletion, for abnormalities in activity, learning and information processing, and cell proliferation; these are the phenotypes that are either affected in patients with BP or commonly assessed in rodent models of BP. The effect of lithium, a drug used to treat BP, was also evaluated for its ability to attenuate Nr2e1(frc/frc) behavioral and neural stem cell-proliferation phenotypes. We show for the first time that Nr2e1-null mice exhibit extreme hyperactivity in the open field as early as postnatal day 18 and in the home cage, deficits in open-field habituation and passive avoidance, and surprisingly, an absence of acoustic startle. We observed a reduction in neural stem/progenitor cell proliferation in Nr2e1(frc/frc) mice, similar to that seen in other Nr2e1-null strains. These behavioral and cell-proliferation phenotypes were resistant to chronic-adult-lithium treatment. Thus, Nr2e1(frc/frc) mice exhibit behavioral traits used to model BP in rodents, but our results do not support Nr2e1(frc/frc) mice as pharmacological models for BP.

Nitric Oxide Synthase Inhibitors as Antidepressants

Affective and anxiety disorders are widely distributed disorders with severe social and economic effects. Evidence is emphatic that effective treatment helps to restore function and quality of life. Due to the action of most modern antidepressant drugs, serotonergic mechanisms have traditionally been suggested to play major roles in the pathophysiology of mood and stress-related disorders. However, a few clinical and several pre-clinical studies, strongly suggest involvement of the nitric oxide (NO) signaling pathway in these disorders. Moreover, several of the conventional neurotransmitters, including serotonin, glutamate and GABA, are intimately regulated by NO, and distinct classes of antidepressants have been found to modulate the hippocampal NO level in vivo. The NO system is therefore a potential target for antidepressant and anxiolytic drug action in acute therapy as well as in prophylaxis. This paper reviews the effect of drugs modulating NO synthesis in anxiety and depression.

Meta-analyses of genetic studies on major depressive disorder

The genetic basis of major depressive disorder (MDD) has been investigated extensively, but the identification of MDD genes has been hampered by conflicting results from underpowered studies. We review all MDD case-control genetic association studies published before June 2007 and perform meta-analyses for polymorphisms that had been investigated in at least three studies. The study selection and data extraction were performed in duplicate by two independent investigators. The 183 papers that met our criteria studied 393 polymorphisms in 102 genes. Twenty-two polymorphisms (6%) were investigated in at least three studies. Seven polymorphisms had been evaluated in previous meta-analyses, 5 of these had new data available. Hence, we performed meta-analyses for 20 polymorphisms in 18 genes. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Statistically significant associations were found for the APOE varepsilon2 (OR, 0.51), GNB3 825T (OR, 1.38), MTHFR 677T (OR, 1.20), SLC6A4 44 bp Ins/Del S (OR, 1.11) alleles and the SLC6A3 40 bpVNTR 9/10 genotype (OR, 2.06). To date, there is statistically significant evidence for six MDD susceptibility genes (APOE, DRD4, GNB3, MTHFR, SLC6A3 and SLC6A4).

Association of functional polymorphisms in NOS1 and NOS3 with loudness dependence of auditory evoked potentials

Nitric oxide (NO) is a gaseous molecule with neurotransmitter properties that is involved in numerous functions in the central nervous system (CNS), the vascular system and also in macrophages. Haplotypes of NOS1 and NOS3 genes have been shown to be associated with different psychiatric disorders such as schizophrenia and bipolar disorder. Therefore, the detection of other characteristics of nitrinergic transmission is desirable. Because nitrinergic functioning influences serotonergic transmission, a functional marker of the serotonergic transmission, the loudness dependence of auditory evoked potentials (LDAEP), can be assumed to be influenced by nitrinergic changes as well. In order to clarify the relationship between nitrinergic transmission and LDAEP, 95 healthy subjects (41 males, 54 females) underwent electrophysiological recording and blood drawing for genotyping of single nucleotide polymorphisms (SNPs) and haplotypes of the NOS1 and NOS3 genes. Interestingly, two functional SNPs in both NOS1 (G-84A_exon 1c promoter polymorphism) and NOS3 (Glu298Asp) were associated with lower LDAEP. Further studies are needed to fully clarify the relationship between nitrinergic transmission, LDAEP and complex disorders such as schizophrenia and affective disorders.

NOS-I and -III gene variants are differentially associated with facets of suicidal behavior and aggression-related traits

Nitric oxide (NO) is a neurotransmitter which modulates depressive and aggressive behaviors. We studied gene variants of NOS-I (rs2682826;rs1353939;rs2293049;rs693534) and NOS-III (rs2070744;rs1799983;rs891512) in a total of 571 cases (167 German suicide attempters, 92 Caucasian suicide completers and 312 German healthy subjects). A NOS-I risk haplotype C-G-G (rs2682826-rs1353939-rs693534) was associated with suicidal behavior (P = 0.01), and more specifically with suicide attempts (P = 0.01). Sliding windows analysis showed similar results for the haplotype G-G (rs1353939-rs693534) being a risk factor for suicidal behavior (P = 0.01) again especially in suicide attempters (P = 0.004). Additionally, the G-allele of rs693534 was associated with suicidal behavior (P = 0.005) and more specifically with suicide attempts (P = 0.003). Interestingly, the same haplotype (G-G) as well as the rs693534 G-allele were also associated with increased aggression. Regarding NOS-III, a protective haplotype C-T-A (rs2070744-rs1799983-rs891512) was observed (P = 0.01) with a pronounced effect against suicide completion (P = 0.005). Sliding window analysis showed the same effect of haplotype T-A (rs1799983-rs891512) (P = 0.01) which was again protective against suicide completion (P = 0.006). Single marker analysis showed the same protective effect of the rs891512 A-allele (P = 0.009) again especially against suicide completion (P = 0.007). Additionally, a second haplotype (T-T-G) was associated with increased aggression (P = 0.0002; sliding haplotype T-G, P = 0.002). In conclusion, our study suggests a possible involvement of NOS-I and NOS-III gene variants in suicidal behavior and related intermediate phenotypes.

Consensus paper of the WFSBP Task Force on Biological Markers: biological markers in depression

Biological markers for depression are of great interest to aid in elucidating the causes of major depression. We assess currently available biological markers to query their validity for aiding in the diagnosis of major depression. We specifically focus on neurotrophic factors, serotonergic markers, biochemical markers, immunological markers, neuroimaging, neurophysiological findings, and neuropsychological markers. We delineate the most robust biological markers of major depression. These include decreased platelet imipramine binding, decreased 5-HT1A receptor expression, increase of soluble interleukin-2 receptor and interleukin-6 in serum, decreased brain-derived neurotrophic factor in serum, hypocholesterolemia, low blood folate levels, and impaired suppression of the dexamethasone suppression test. To date, however, none of these markers are sufficiently specific to contribute to the diagnosis of major depression. Thus, with regard to new diagnostic manuals such as DSM-V and ICD-11 which are currently assessing whether biological markers may be included in diagnostic criteria, no biological markers for major depression are currently available for inclusion in the diagnostic criteria.

Lack of association between endothelial nitric oxide synthase (NOS3) gene polymorphisms and suicide attempts

OBJECTIVE

The aim of this study is to investigate the association between two polymorphisms of endothelial nitric oxide synthase (NOS3) and suicide attempts.

METHODS

We genotyped 186 suicide attempters and 420 unrelated healthy controls. The following polymorphisms were analysed: T-786C and 27-bp repeat in intron 4.

RESULTS

No significant differences were found in genotype or in allelic distribution of the aforesaid polymorphisms. There were also no differences in the genotype distribution or allelic frequencies when separately assessing males and females or impulsive and non-impulsive attempters and normal controls. Estimated haplotype frequencies were similar in both groups.

CONCLUSION

Our data do not support the hypothesis that genetically determined changes in the NOS3 gene confer increased susceptibility for suicidal behavior.

Changes in nitric oxide level and superoxide dismutase activity during antimanic treatment

Oxidant nitric oxide (NO) and antioxidant superoxide dismutase (SOD) have been implicated to play a role in the pathogenesis of bipolar disorders. This is the first prospective study aimed to evaluate NO levels and SOD activity in bipolar disorder (type I manic episode) (BD-ME). 29 inpatient subjects with BD-ME and 30 healthy controls were included. Serum NO levels and SOD activity have been studied at 1st (NO [1st] and SOD [1st] respectively) and 30th days (NO [30th] and SOD [30th] respectively) after treatment. The clinical outcome was measured by Bech-Rafaelson Mania Scale (BRMS). The mean NO [1st] (p<.001) and NO [30th] levels (p<.001) were higher than controls, but SOD [1st] (p<.001) and SOD [30th] (p<.001) activities in BD-ME were lower than controls. SOD(1) activity was higher than SOD [30th] (p<.001), while there was no significance in comparison between NO [1st] and NO [30th] (p>.05). SOD [30th] activity is negatively correlated with the number of previous manic attacks and NO [1st] was negatively correlated with sleep item score of BRMS at first day. Also there was a significant correlation between NO [1st] levels and with the existence of a delusion. NO and SOD appear to play a role in the pathophysiological events occurring in BD, especially in BD-ME. This study for the first time showed the possible role of NO on sleep and the generation of delusions in the pathophysiology of BD. In the light of literature, induced glutamate pathway might be responsible for delusions in BD. The results of this research need further investigation to understand the oxidative vs antioxidative process in BD.

Behavioural and expressional phenotyping of nitric oxide synthase-I knockdown animals

The gaseous messenger nitric oxide (NO) has been implicated in a wide range of behaviors, including aggression, anxiety, depression, and cognitive functioning. To further elucidate the physiological role of NO and its down-stream mechanisms, we conducted behavioral and expressional phenotyping of mice lacking the neuronal isoform of nitric oxide synthase (NOS-I), the major source of NO in the central nervous system. No differences were observed in activity-related parameters; in contrast to the a priori hypothesis, derived from pharmacological treatments, depression-related tests (Forced Swim Test, Learned Helplessness) also yielded no significantly different results. A subtle anxiolytic phenotype however was present, with knockdown mice displaying a higher open arm time as compared to their respective wildtypes, yet all other investigated anxiety-related parameters were unchanged. The most prominent feature however was gender-independent cognitive impairment in spatial learning and memory, as assessed by the Water Maze test and an automatized holeboard paradigm. No significant dysregulation of monoamine transporters was evidenced by qRT PCR. To further examine the underlying molecular mechanisms, the transcriptome of knockdown animals was thus examined in the hippocampus, striatum and cerebellum by microarray analysis. A set of >120 differentially expressed genes was identified, whereat the hippocampus and the striatum showed similar expressional profiles as compared to the cerebellum in hierarchical clustering. Among the most significantly up-regulated genes were Peroxiredoxon 3, Atonal homologue 1, Kcnj1, Kcnj8, CCAAT/enhancer binding protein (C/EBP), alpha, 3 genes involved in GABA(B) signalling and, intriguingly, the glucocorticoid receptor GR. While GABAergic genes might underlie reduced anxiety, dysregulation of the glucocorticoid receptor can well contribute to a blunted stress response as found in NOS1 knockdown mice. Furthermore, by CREB inhibition, glucocorticoid receptor upregulation could at least partially explain cognitive deficits in these animals. Taken together, NOS1 knockdown mice display a characteristic behavioural profile consisting of reduced anxiety and impaired learning and memory, paralleled by differential expression of the glucocorticoid receptor and GABAergic genes. Further research has to assess the value of these mice as animal models e.g. for Alzheimer's disease or attention deficit disorder, in order to clarify a possible pathophysiological role of NO therein.

Homocysteinemia as well as methylenetetrahydrofolate reductase polymorphism are associated with affective psychoses

In the recent years, elevated homocysteine plasma levels have been reported to represent a risk factor not only for atherosclerosis, but also to be associated with dementia, depression and-in a gender-specific manner-schizophrenia. Here, we explored a possible association between homocysteinemia and psychiatric disorders. Fasting homocysteine, vitamin B12 and folate were determined in an ethnically homogeneous female population with different psychiatric disorders. Homocysteine was not elevated in females suffering from schizophrenia (mean, 11.6+/-5.8 micromol/l). As shown previously, increased homocysteine concentrations were associated not only with dementia of different aetiology (mean, 17.2+/-6.7 micromol/l; chi2=23.39, p<0.001, compared to the schizophrenia group), but also with depressive disorders (mean, 12.9+/-3.8 micromol/l; chi2=6.88, p=0.009). B12 and folate levels did not differ between different diagnostic groups. To further explore the connection between homocysteinemia and affective psychoses, a case-control study examining the C677T and the A1298C variants of methylenetetrahydrofolate reductase was conducted. The latter polymorphism not only was associated with affective psychoses in general, but also when divided in unipolar depression and bipolar affective disorder. In conclusion, we suggest that in females homocysteinemia is an unspecific risk factor for organic brain disorders like dementia, and possibly depression, but not for schizophrenia.