A genome-wide association study identifies two novel susceptibility loci and trans population polygenicity associated with bipolar disorder.

Genome-wide association studies (GWASs) have identified several susceptibility loci for bipolar disorder (BD) and shown that the genetic architecture of BD can be explained by polygenicity, with numerous variants contributing to BD. In the present GWAS (Phase I/II), which included 2964 BD and 61 887 control subjects from the Japanese population, we detected a novel susceptibility locus at 11q12.2 (rs28456, P=6.4 × 10-9), a region known to contain regulatory genes for plasma lipid levels (FADS1/2/3). A subsequent meta-analysis of Phase I/II and the Psychiatric GWAS Consortium for BD (PGC-BD) identified another novel BD gene, NFIX (Pbest=5.8 × 10-10), and supported three regions previously implicated in BD susceptibility: MAD1L1 (Pbest=1.9 × 10-9), TRANK1 (Pbest=2.1 × 10-9) and ODZ4 (Pbest=3.3 × 10-9). Polygenicity of BD within Japanese and trans-European-Japanese populations was assessed with risk profile score analysis. We detected higher scores in BD cases both within (Phase I/II) and across populations (Phase I/II and PGC-BD). These were defined by (1) Phase II as discovery and Phase I as target, or vice versa (for 'within Japanese comparisons', Pbest~10-29, R2~2%), and (2) European PGC-BD as discovery and Japanese BD (Phase I/II) as target (for 'trans-European-Japanese comparison,' Pbest~10-13, R2~0.27%). This 'trans population' effect was supported by estimation of the genetic correlation using the effect size based on each population (liability estimates~0.7). These results indicate that (1) two novel and three previously implicated loci are significantly associated with BD and that (2) BD 'risk' effect are shared between Japanese and European populations.

Delays in psychiatric drug development in Japan.

WHAT IS KNOWN AND OBJECTIVE: The lag in the approval and development of psychiatric drugs between Japan and other countries has been a major issue both for patients with psychiatric diseases and for psychiatrists. The objective of this study was to analyse factors contributing to delays in launching new psychiatric drugs in Japan. METHODS: We analysed data from Japan, the USA, and the UK for the approval of 23 standard psychiatric drugs and examined potential factors that might have contributed the delay of their launch. RESULTS: Of the 23 standard psychiatric drugs, all of which were approved in the USA and the UK, only 13 were introduced in Japan between September 2000 and July 2011. None of their development strategies adopted the ICH E5 guideline on simultaneous development of drugs on a global scale. Twelve of the 13 drugs (not including atomoxetine) were approved in Japan after their approval in the USA and the UK. The median review time (from approval application to approval) of these 13 drugs in Japan was 23 months, which was considerably longer than those of the US Food and Drug Administration and European Medicines Agency (10·0 and 13·5 months, respectively). The 10-13-month difference in review time cannot explain the overall 87- and 51-month delay in Japan after approval in the USA or UK. WHAT IS NEW AND CONCLUSION: There remains a large gap between Japan and Western countries, such as the USA and the UK, with regard to access to standard psychiatric drugs, despite several important reforms in the Japanese drug approval system.

Aberrant DNA methylation associated with bipolar disorder identified from discordant monozygotic twins.

To search DNA methylation difference between monozygotic twins discordant for bipolar disorder, we applied a comprehensive genome scan method, methylation-sensitive representational difference analysis (MS-RDA) to lymphoblastoid cells derived from the twins. MS-RDA isolated 10 DNA fragments derived from 5' region of known genes/ESTs. Among these 10 regions, four regions showed DNA methylation differences between bipolar twin and control co-twin confirmed by bisulfite sequencing. We performed a case-control study of DNA methylation status of these four regions by pyrosequencing. Two regions, upstream regions of spermine synthase (SMS) and peptidylprolyl isomerase E-like (PPIEL) (CN265253), showed aberrant DNA methylation status in bipolar disorder. SMS, a gene on X chromosome, showed significantly higher DNA methylation level in female patients with bipolar disorder compared with control females. However, there was no difference of mRNA expression. In PPIEL, DNA methylation level was significantly lower in patients with bipolar II disorder than in controls. The expression level of PPIEL was significantly higher in bipolar II disorder than in controls. We found strong inverse correlation between gene expression and DNA methylation levels of PPIEL. These results suggest that altered DNA methylation statuses of PPIEL might have some significance in pathophysiology of bipolar disorder..

Human leukocyte antigen and season of birth in Japanese patients with schizophrenia.

OBJECTIVE: Five Japanese studies, to the authors' knowledge, without exception, have consistently shown an increased frequency of human leukocyte antigen (HLA)-DR1 in patients with schizophrenia. This suggests an association between HLA-DR1 and schizophrenia in the Japanese population. The mechanism of the association is unknown; however, prenatal infections may be involved. The present study explored factors, including winter birth, that might correlate with this mechanism. Age at onset and gender were also studied. METHOD: Factors were compared between Japanese patients with schizophrenia with and in those without HLA-DR1 (N=60 and N=307, respectively). RESULTS: A significantly higher incidence of births in February and March was observed in patients with (31.7%) than those without (15. 6%) HLA-DR1. No association was found between the presence of HLA-DR1 and other variables. CONCLUSIONS: Although this result is preliminary, it may suggest an interaction between HLA and winter birth in the development of schizophrenia in the Japanese population.

Treatment response in depressed patients with enhanced Ca mobilization stimulated by serotonin.

Serotonin (5-HT)-stimulated intraplatelet calcium (Ca) mobilization has been shown to be enhanced in nonmedicated depressive patients by many studies. However, there has not been any longitudinal follow-up study of this parameter. We examined the relationship between treatment response and pretreatment value of the 5-HT-induced Ca response. The 5-HT(10 microM)-induced intraplatelet Ca mobilization was measured in 98 nonmedicated depressive patients (24 bipolar disorders, 51 melancholic major depressive disorders, and 23 non-melancholic major depressive disorders). These patients were followed up prospectively for a further period of five years. The depressed patients with enhanced Ca response to 5-HT in bipolar disorders exhibited a good response to mood stabilizers but those with major depressive disorders showed a poor response to antidepressants. These findings suggest the possibility that the 5-HT-induced intraplatelet Ca response may be a good predictor of treatment response in depressed patients. Longer longitudinal follow-up studies are needed in larger samples to examine if this parameter may be a specific biological marker for unipolar-bipolar dichotomy.

Effects of citalopram on dopamine D2 receptor expression in the rat brain striatum.

Effects of citalopram on dopamine D2 receptor expression in the rat brain striatum were studied. Repeated administration of citalopram increased the amount of dopamine D2 receptors, the level of dopamine D2 receptor mRNA, and the transcription rate of the dopamine D2 receptor gene. Single administration of citalopram also increased the level of dopamine D2 receptor mRNA with a maximum effect in 2-4 h after the treatment, and the transcription rate of the dopamine D2 receptor gene. The administration of 5-hydroxytryptophan (5-HTP) also increased the level of dopamine D2 receptor mRNA. These results suggest that the increase in the dopamine D2 receptor expression induced by citalopram may be owing, at least partially, to the stimulation of the dopamine D2 receptor gene transcription, and that serotonin (5-HT) may mediate the effects of citalopram in the induction of dopamine D2 receptor expression.

A serotonin-4 receptor-like pseudogene in humans.

During a search for new G-protein-linked receptors for dopamine and serotonin, we found a serotonin-4 receptor-like pseudogene. This receptor-like pseudogene is intronless, contains an in-frame stop codon following transmembrane-3, and has two one-nucleotide insertions between transmembrane-5 and -6 regions which alter the reading frame. The predicted amino acid sequence of the human pseudogene is about 35% identical with that of the rat serotonin-4 receptor.

A human serotonin-7 receptor pseudogene.

Although the serotonin-7 receptor was cloned several years ago, its localization in brain tissues remains confusing because of the existence of a related expressed pseudogene, the sequence of which has not hitherto been reported. During the course of searching for related receptor genes, we also searched for this pseudogene to determine its sequence. Human genomic DNA was screened for dopamine and serotonin receptor-like genes, using the polymerase chain reaction method and degenerate oligonucleotide primers based on the similar sequences in the transmembrane-6 and -7 regions of the serotonin-5A, the serotonin-7, and the dopamine D2, D3 and D4 receptors. This resulted in one of the clones having a 115 bp fragment, of which 89% of the bases were identical to the transmembrane-6 and -7 regions of the serotonin-7 receptor sequence. The fragment was radiolabelled and used to screen a human fetal brain cDNA library. A novel cDNA clone of 1326 bp was isolated. Based on the nucleotide sequence, 88% of the bases in this sequence of the pseudogene are identical to the human serotonin-7 receptor coding sequence. However, compared to the serotonin-7 receptor DNA sequence, the pseudogene sequence has nucleotide deletions and insertions, resulting in frame-shifts and stop codons. It was concluded that this sequence represented a pseudogene related to the serotonin-7 receptor gene.

Serotonin-induced platelet intracellular calcium mobilization in depressed patients.

Serotonin(5-HT)-stimulated intracellular calcium(Ca) mobilization was measured in the platelets of depressed patients to assess 5-HT2 receptor function. The 5-HT-induced Ca response was significantly higher in unmedicated patients with bipolar depression and melancholic major depression than in those with non-melancholic major depression and normal controls. The enhanced Ca response to 5-HT failed to correlate with severity of depressive symptoms. In patients with bipolar disorder and melancholic major depression, there was no significant difference in 5-HT-stimulated Ca response between the unmedicated group and those in remission. These results suggest that 5-HT2 receptor function is increased in some types of depression, and raise the possibility that the enhanced Ca response to 5-HT may be trait dependent rather than state dependent.

Effects of serotonergic agents on the up-regulation of dopamine D2 receptors induced by haloperidol in rat striatum.

We examined the modulatory effect of serotonergic activities on haloperidol-induced up-regulation of dopamine D2 receptors in rat striatum. Chronic treatment with haloperidol (0.1, 0.5 mg/kg, i.p., 3 weeks) increased the number of dopamine D2 receptors, while no increase was observed with the atypical antipsychotic drugs clozapine (10 mg/kg) and trans-5-chloro-2-methyl-2,3,3a, 12b-tetrahydro-1 H-dibenz[2,3:6,7]oxepino[4,5-c]pyrrolidine maleate (ORG 5222; 0.25 mg/kg). Chronic treatment with 6-chloro-2-(1-piperazinyl)pyrazine (MK-212), a nonselective serotonin (5-hydroxytryptamine, 5-HT) receptor agonist (2.5 mg/kg), or with citalopram, a 5-HT reuptake inhibitor (10 mg/kg), potentiated the haloperidol (0.1 mg/kg)-induced up-regulation of dopamine D2 receptors, while that with (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a 5-HT1A receptor agonist (0.1 mg/kg) had no influence on the dopamine D2 receptor up-regulation. Coadministration of ritanserin (1 mg/kg), a 5-HT2A/2C receptor antagonist, with a low dose of haloperidol (0.1 mg/kg), but not with a high dose of the agent (0.5 mg/kg) attenuated the dopamine D2 receptor up-regulation, Drug occupation of 5-HT2A and dopamine D2 receptors in vivo examined using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) was 69.8% and 45.1%, respectively, after the acute administration of haloperidol (0.1 mg/kg) plus ritanserin (1 mg/kg). This profile, that 5-HT2A receptors are highly occupied compared with dopamine D2 receptors, was similar to that of clozapine or ORG 5222. These results suggest that potent 5-HT2A receptor antagonism versus weak dopamine D2 receptor blockade may be involved in the absence of up-regulation of dopamine D2 receptors after chronic treatment with clozapine or ORG 5222.

Effect of subchronic antidepressants administration on serotonin-stimulated phosphoinositide hydrolysis in para-chlorophenylalanine-treated rat hippocampal slices.

1. This study examines the effect of subchronic parachlorophenylalanine (PCPA) treatment upon serotonin (5-HT)-stimulated inositol monophosphate (IP-1) accumulation in rat hippocampal slices and also the effect of antidepressants upon this 5-HT response in the hippocampus from rats treated with or without concurrent administration of PCPA. 2. For high dose PCPA treatment, animals were injected intraperitoneally with 300 mg/kg daily for the first 5 days and then 100 mg/kg for 5 days, while for low dose PCPA treatment animals were injected for 10 days at a dose of 100 mg/kg. Imipramine or iprindole (15 mg/kg i.p.) was given once daily for 10 consecutive days. 3. 10-Day treatment with high dose of PCPA resulted in a significant increase in 5-HT-stimulated IP-1 accumulation, whereas low dose of PCPA had no significant effect upon the 5-HT response as compared to vehicle. 5-HT-stimulated IP-1 accumulation in rat hippocampus was not affected by subchronic treatment with imipramine or iprindole. The enhancement of the 5-HT response induced by high dose of PCPA was not attenuated by repeated antidepressants treatment.

Effects of acute citalopram treatment on the methamphetamine-induced locomotor activity.

1. Previously the authors have shown that acute citalopram treatment increased the dopamine D2 receptor expression in rat brain striatum (Kameda et al., 2000). In the present study, the authors attempted to determine whether these effects of citalopram influence the methamphetamine-induced locomotor activity. 2. The pretreatment with a single administration of citalopram (10 mg/kg, i.p.) resulted in the significant enhancement of the locomoter activity induced by methamphetamine treatment (1 mg/kg, i.p.). The enhancement was observed 30 min, 12 hours, 24 hours, but not 7 days after withdrawal of citalopram administration. 3. Then the authors determined the methamphetamine concentration in rat brain striatum by gas chromatography-mass spectrometry (GC-MS) The results showed that the concentration of methamphetamine wars significantly higher in the rats 24 hours, and also 7 days after withdrawal of citalopram administration, compared to the control rats. 4. These results emphasized the involvement of the high methamphetamine concentration, caused by the pretreatment with citalopram, in the enhancement of the methamphetamine-induced locomotor activity. However high methamphetamine concentration alone could not account for this enhancement, since the high concentration of methamphetamine observed 7 days after withdrawal of citalopram administration did not appear to enhance the methamphetamine-induced locomotor activity. Another mechanism through which the pretreatment with citalopram enhanced the methamphetamine-induced locomotor activity, such as the increased expression of the dopamine D2 receptors, could not be excluded.

Increased 5-HT-2 receptor function as measured by serotonin-stimulated phosphoinositide hydrolysis in platelets of depressed patients.

1. The present study was undertaken to examine whether or not 5-HT-induced inositol monophosphate (IP-1) accumulation in human platelets is mediated by 5-HT-2 receptors and to assess 5-HT-2 receptor function as measured by 5-HT-stimulated IP-1 accumulation in platelets from normal controls and depressed patients before drug treatment. 2. In platelets prelabeled with 3H-myo-inositol, in Ca ion free HEPES buffer containing 10 mM LiCl, 5-HT caused a dose-dependent accumulation of IP-1 during 15 min incubation. A maximal increase in IP-1 formation was observed at 30 microM of 5-HT and its EC50 value was 4 microM. 3. Ketanserin, a selective 5-HT-2 antagonist, was a potent inhibitor of 5-HT-stimulated IP-1 accumulation with a Ki value of 12 nM, but (-)propranolol (10 microM), a 5-HT-1 antagonist, failed to block the 5-HT response. 4. The potencies of various compounds tested to inhibit 5-HT-stimulated IP-1 accumulation in human platelets correlated positively with the affinities to 5-HT-2 receptor as defined by radioligand binding in rat cerebral cortex. 5. In a group of unmedicated patients with major depressive disorder matched for age with normal control group, we found a significant increase in 5-HT (100 microM)-induced accumulation of IP-1 (150 +/- 7% of basal for depressed patients, 132 +/- 3% for controls).

Differential expression of matrix metalloprotease-7 in each component of uterine carcinosarcoma.

The aim of this study was to investigate the expression of matrix metalloprotease-7 (MMP-7) in each component of uterine carcinosarcoma. Surgical specimens of primary tumors of uterine carcinosarcomas were obtained from 13 patients. The carcinomatous component consisted of adenocarcinoma with or without squamous differentiation. The sarcomatous component consisted of spindle cell sarcoma, chondrosarcoma and rhabdomyosarcoma, either alone or in combination. The immunohistochemical expression of MMP-7 protein was examined using the avidin-biotin peroxidase complex technique employing the anti-MMP-7 monoclonal antibody. Expression of MMP-7 protein was detected in 9 (69.2%) of 13 adenocarcinoma components, while no staining was observed in any of the sarcomatous components examined. There was a statistically significant difference of the positive rate for MMP-7 between epithelial components and sarcomatous components of uterine carcinosarcoma (p<0.01). In some cases, MMP-7 was abundantly expressed at the invasive front of adenocarcinomas. It is concluded that MMP-7 protein is differentially expressed between the carcinomatous component and the sarcomatous component of uterine carcinosarcoma. Each component of carcinosarcoma may have its own potential for invasion and metastasis. MMP-7 may contribute to the invasive nature or growth capacity of the carcinomatous component of uterine carcinosarcoma, while it may not have a relation to that of the sarcomatous components.

Serotonin-induced platelet intracellular calcium mobilization in various psychiatric disorders: is it specific to bipolar disorder?

BACKGROUND: Serotonin (5-HT)-stimulated platelet intracellular calcium (Ca) mobilization has been reported to be enhanced in unmedicated depressive patients compared to those of normal healthy subjects, which suggests increased 5-HT2A receptor function in these patients. It has not been ascertained whether this enhanced response is specific to some type of affective disorders among various mental disorders. METHODS: We examined 5-HT-induced platelet intracellular Ca response in 152 unmedicated outpatients with various psychiatric disorders including bipolar disorder (BD), major depressive disorder with melancholia (DM), major depressive disorder without melancholia (DN), schizophrenia (SCH), panic disorder (PD), obsessive-compulsive disorder (OCD), social phobia (SP) and bulimia nervosa (BN), and 30 normal controls. RESULTS: We observed no significant differences in basal intracellular Ca concentration among all patient subgroups and normal controls. While the 5-HT-induced Ca response was significantly and specifically higher in patients with BD than in normal controls, no significant differences were found in the Ca response to 5-HT between patients with DM, DN, SCH, PD, OCD, SP and BN, and normal controls. LIMITATIONS: The sample sizes of each group are still small. Therefore, they have to be enlarged in the continuation of the study so as to increase the power of the statistical tests. CONCLUSION: These results indicate the possibility that enhanced signal transduction, mediated by the 5-HT2A receptor, may be specific to bipolar disorder.

Nucleotide sequence analysis of the binding site on the inositol 1,4,5-trisphosphate type-1 receptor in bipolar disorder -- a negative study.

Pharmacological studies of bipolar disorder suggest that dysfunction of calcium mobilization via phosphatidylinositol-mediated transduction may be involved in its pathogenesis. The present study tests the hypothesis that dysfunction of calcium mobilization in bipolar disorder is due to the mutation of the nucleotide sequence in the FKBP12 binding site on the inositol 1,4,5-trisphosphate type-1 receptor (IP(3)R1). Nucleotide sequence analysis of the FKBP12 binding site on IP(3)R1 was performed using reverse transcription-polymerase chain reaction and DNA sequencing. The nucleotide sequence in this region was preserved in all subjects. This finding suggests that IP(3)R1 dysfunction through the FKBP12 binding site is not involved in the pathogenesis of bipolar disorder.

Open pergolide treatment of tricyclic and heterocyclic antidepressant-resistant depression.

BACKGROUND: Recently, a dopamine hypothesis of depression was put forward, and several studies have demonstrated that direct and indirect dopamine agonists have antidepressant effects. METHODS: Using Clinical Global Impressions, we evaluated the efficacy of 4-week treatment of pergolide as an antidepressant adjuvant involving 20 unipolar depressed patients who were refractory to standard treatment with antidepressants. RESULTS: One patients (5%) were very much improved, seven (35%) much improved, four (20%) minimally improved, six (30%) no change or worse, and two (10%) not assessed. There was no significant difference in any clinical factors between the pergolide responder and non-responder group. LIMITATIONS: This study was a non-blind open trial, and pergolide was added to tricyclic and heterocyclic antidepressants. CONCLUSION: Pergolide may be useful as an antidepressant adjuvant, suggesting a potential role for dopamine-2 stimulation in the antidepressant response.

Effect of various factors on serotonin-induced Ca2+ response in human platelets.

Serotonin (5-HT)-stimulated intracellular Ca2+ concentration change was studied in the platelets of healthy subjects, using fluorescent Ca indicator fura-2. 5-HT increased the Ca2+ response in a concentration-dependent manner. 10 microM of 5-HT induced the maximal response and its EC50 value was 0.4 microM. This response was potently inhibited by selective 5-HT2 antagonists, suggesting that 5-HT-induced Ca2+ mobilization in human platelets is mediated by 5-HT2 receptors. This 5-HT2-mediated Ca2+ response was not significantly affected by the time of blood sampling, gender, meal or exercise. However, this response declined with time after blood drawing, suggesting that it must be measured as soon as possible after sampling. These results indicate that 5-HT-stimulated Ca2+ response in human platelets is a stable parameter and that it will be suitable for assessing 5-HT2 receptor function in depressed patients.

[Serotonin-2 receptor-mediated intraplatelet calcium mobilization in affective disorders: relevance to the pathophysiology of depression].

Abnormal serotonin-2(5-HT2) receptor function in the central nervous system has been suggested to play a role in the pathogenesis of affective disorders. The presence of 5-HT2 receptors on human platelet similar to those in brain may permit direct study of 5-HT2 receptor function in living persons. 5-HT-stimulated intracellular calcium (Ca) concentration change was studied in the platelets of healthy subjects, using fluorescent Ca indicator fura-2. 5-HT increased the Ca response in a concentration-dependent manner. The maximal response was obtained at 10 microM of 5-HT and its EC50 value was 0.4 microM. This response was potently inhibited by selective 5-HT2 receptor antagonists, suggesting that the 5-HT-induced Ca mobilization is mediated by 5-HT2 receptors. This 5-HT-stimulated Ca response was not significantly affected by the time of blood sampling, gender, age, meal or exercise. Therefore, it may be concluded that the 5-HT-induced Ca response in human platelets is a stable parameter and that it is suitable for assessing 5-HT2 receptor function in depressed patients. Thus, the 5-HT-induced Ca mobilization was measured in the platelets of depressed patients. The response was significantly higher in unmedicated patients with bipolar depression and melancholic major depression than in those with non-melancholic major depression and normal controls. The enhanced Ca response to 5-HT failed to correlate with severity of depressive symptoms. In patients with bipolar depression and melancholic major depression, there was no significant difference in 5-HT-stimulated Ca response between unmediated group and euthymic-treated group. These results suggest that 5-HT2 receptor function is increased in some type of affective disorders and that the enhanced Ca response to 5-HT may be trait dependent rather than state dependent.

Hypermethylation of serotonin transporter gene in bipolar disorder detected by epigenome analysis of discordant monozygotic twins.

Bipolar disorder (BD) is a severe mental disorder characterized by recurrent episodes of mania and depression. Serotonin transporter (HTT) is a target of antidepressants and is one of the strongest candidate molecules of mood disorder, however, genetic study showed equivocal results. Here, we performed promoter-wide DNA methylation analysis of lymphoblastoid cell lines (LCLs) derived from two pairs of monozygotic twins discordant for BD. To rule out the possible discordance of copy number variation (CNV) between twins, we performed CNV analysis and found the copy number profiles were nearly identical between the twin pairs except for immunoglobulin-related regions. Among the three genes we obtained as candidate regions showing distinct difference of DNA methylation between one of the two pairs, hypermethylation of SLC6A4, encoding HTT, in the bipolar twin was only confirmed by bisulfite sequencing. Then, promoter hypermethylation of SLC6A4 in LCLs of BD patients was confirmed in a case-control analysis. DNA methylation of SLC6A4 was significantly correlated with its mRNA expression level in individuals with the S/S genotype of HTTLPR, and mRNA expression level was lower in BD patients carrying the S/S genotype. Finally, DNA methylation of the same site was also higher in the postmortem brains of BD patients. This is the first study to report the role of epigenetic modification of SLC6A4 in BD using an unbiased approach, which provides an insight for its pathophysiology.